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Articles de revues sur le sujet « Synthèse peptique »

Auteur : Grafiati
Publié le 4 juin 2021
Mis à jour le 6 février 2022

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1

Moolhuijzen, Paula M., Mariano Jordi Muria-Gonzalez, Robert Syme, Catherine Rawlinson, Pao Theen See, Caroline S. Moffat et Simon R. Ellwood. « Expansion and Conservation of Biosynthetic Gene Clusters in Pathogenic Pyrenophora spp. » Toxins 12, no 4 (9 avril 2020) : 242. http://dx.doi.org/10.3390/toxins12040242.

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Pyrenophora is a fungal genus responsible for a number of major cereal diseases. Although fungi produce many specialised or secondary metabolites for defence and interacting with the surrounding environment, the repertoire of specialised metabolites (SM) within Pyrenophora pathogenic species remains mostly uncharted. In this study, an in-depth comparative analysis of the P. teres f. teres, P teres f. maculata and P. tritici-repentis potential to produce SMs, based on in silico predicted biosynthetic gene clusters (BGCs), was conducted using genome assemblies from PacBio DNA reads. Conservation of BGCs between the Pyrenophora species included type I polyketide synthases, terpene synthases and the first reporting of a type III polyketide synthase in P teres f. maculata. P. teres isolates exhibited substantial expansion of non-ribosomal peptide synthases relative to P. tritici-repentis, hallmarked by the presence of tailoring cis-acting nitrogen methyltransferase domains. P. teres isolates also possessed unique non-ribosomal peptide synthase (NRPS)-indole and indole BGCs, while a P. tritici-repentis phytotoxin BGC for triticone production was absent in P. teres. These differences highlight diversification between the pathogens that reflects their different evolutionary histories, host adaption and lifestyles.
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Harken, Lauritz, et Shu-Ming Li. « Modifications of diketopiperazines assembled by cyclodipeptide synthases with cytochrome P450 enzymes ». Applied Microbiology and Biotechnology 105, no 6 (24 février 2021) : 2277–85. http://dx.doi.org/10.1007/s00253-021-11178-1.

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Abstract2,5-Diketopiperazines are the smallest cyclic peptides comprising two amino acids connected via two peptide bonds. They can be biosynthesized in nature by two different enzyme families, either by nonribosomal peptide synthetases or by cyclodipeptide synthases. Due to the stable scaffold of the diketopiperazine ring, they can serve as precursors for further modifications by different tailoring enzymes, such as methyltransferases, prenyltransferases, oxidoreductases like cyclodipeptide oxidases, 2-oxoglutarate-dependent monooxygenases and cytochrome P450 enzymes, leading to the formation of intriguing secondary metabolites. Among them, cyclodipeptide synthase-associated P450s attracted recently significant attention, since they are able to catalyse a broader variety of astonishing reactions than just oxidation by insertion of an oxygen. The P450-catalysed reactions include hydroxylation at a tertiary carbon, aromatisation of the diketopiperazine ring, intramolecular and intermolecular carbon-carbon and carbon-nitrogen bond formation of cyclodipeptides and nucleobase transfer reactions. Elucidation of the crystal structures of three P450s as cyclodipeptide dimerases provides a structural basis for understanding the reaction mechanism and generating new enzymes by protein engineering. This review summarises recent publications on cyclodipeptide modifications by P450s.Key Points• Intriguing reactions catalysed by cyclodipeptide synthase-associated cytochrome P450s• Homo- and heterodimerisation of diketopiperazines• Coupling of guanine and hypoxanthine with diketopiperazines Graphical abstract
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Gao, Ming, et Ravindra N. Chibbar. « Isolation, characterization, and expression analysis of starch synthase IIa cDNA from wheat (Triticum aestivum L.) ». Genome 43, no 5 (1 octobre 2000) : 768–75. http://dx.doi.org/10.1139/g00-046.

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We characterized three near-full-length putative homoeologous cDNA (Ss2a-1, Ss2a-2, and Ss2a-3) in wheat endosperm most similar to the maize zSSIIa. Polypeptide sequences deduced from three Ss2a cDNA clones share a 95% overall sequence similarity, and may thus have similar biochemical properties and may make identical contributions to starch biosynthesis in wheat endosperm. The accumulation of RNA transcripts corresponding to three Ss2a genes in developing endosperm varies among three cultivars studied, but usually peaks in young endosperm at about 10 days post anthesis (DPA). The polyclonal antibody for the SSIIa-1 recombinant protein strongly reacted to three previously identified granule-bound starch synthases of 100 to 115 kDa. The polyclonal antibody for the granule-bound starch synthases strongly reacted to the SSIIa-1 recombinant protein. Sequences of the N-terminal and an internal peptide of these three granule-bound starch synthases match well with those of three predicted mature SSIIa polypeptides. These granule-bound starch synthases may therefore be SSIIa polypeptides. The antibodies also recognized a group of three polypeptides with the same gel mobility as the three granule-bound starch synthases, a polypeptide of 90 kDa, and a group of three polypeptides of about 80 to 82 kDa. Thus, the wheat SSIIa may exist in several functional forms in the stroma of amyloplasts.Key words: starch granule, granule-bound proteins, soluble starch synthase, homoeologous isoforms, starch biosynthesis.
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Andre, M., C. Syldatk et J. Rudat. « Protease-katalysierte Synthese kurzkettiger Peptide ». Chemie Ingenieur Technik 82, no 9 (27 août 2010) : 1523. http://dx.doi.org/10.1002/cite.201050364.

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Nishibori, Ayako, Jin Kusaka, Hiroshi Hara, Masato Umeda et Kouji Matsumoto. « Phosphatidylethanolamine Domains and Localization of Phospholipid Synthases in Bacillus subtilis Membranes ». Journal of Bacteriology 187, no 6 (15 mars 2005) : 2163–74. http://dx.doi.org/10.1128/jb.187.6.2163-2174.2005.

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ABSTRACT Application of the cardiolipin (CL)-specific fluorescent dye 10-N-nonyl-acridine orange has recently revealed CL-rich domains in the septal regions and at the poles of the Bacillus subtilis membrane (F. Kawai, M. Shoda, R. Harashima, Y. Sadaie, H. Hara, and K. Matsumoto, J. Bacteriol. 186:1475-1483, 2004). This finding prompted us to examine the localization of another phospholipid, phosphatidylethanolamine (PE), with the cyclic peptide probe, Ro09-0198 (Ro), that binds specifically to PE. Treatment with biotinylated Ro followed by tetramethyl rhodamine-conjugated streptavidin revealed that PE is localized in the septal membranes of vegetative cells and in the membranes of the polar septum and the engulfment membranes of sporulating cells. When the mutant cells of the strains SDB01 (psd1::neo) and SDB02 (pssA10::spc), which both lack PE, were examined under the same conditions, no fluorescence was observed. The localization of the fluorescence thus evidently reflected the localization of PE-rich domains in the septal membranes. Similar PE-rich domains were observed in the septal regions of the cells of many Bacillus species. In Escherichia coli cells, however, no PE-rich domains were found. Green fluorescent protein fusions to the enzymes that catalyze the committed steps in PE synthesis, phosphatidylserine synthase, and in CL synthesis, CL synthase and phosphatidylglycerophosphate synthase, were localized mainly in the septal membranes in B. subtilis cells. The majority of the lipid synthases were also localized in the septal membranes; this includes 1-acyl-glycerol-3-phosphate acyltransferase, CDP-diacylglycerol synthase, phosphatidylserine decarboxylase, diacylglycerol kinase, glucolipid synthase, and lysylphosphatidylglycerol synthase. These results suggest that phospholipids are produced mostly in the septal membranes and that CL and PE are kept from diffusing out to lateral ones.
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Deska, Jan, et Uli Kazmaier. « Stereoselektive Synthese und Umsetzung stannylierter Peptide ». Angewandte Chemie 119, no 24 (11 juin 2007) : 4654–57. http://dx.doi.org/10.1002/ange.200700759.

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Barekzi, Nazir, Swati Joshi, Scott Irwin, Todd Ontl et Herbert P. Schweizer. « Genetic characterization of pcpS, encoding the multifunctional phosphopantetheinyl transferase of Pseudomonas aeruginosa ». Microbiology 150, no 4 (1 avril 2004) : 795–803. http://dx.doi.org/10.1099/mic.0.26823-0.

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Fatty acid synthases (primary metabolism), non-ribosomal peptide synthases and polyketide synthases (secondary metabolism) contain phosphopantetheinyl (Ppant)-dependent carrier proteins that must be made functionally active by transfer of the 4′-Ppant moiety from coenzyme A. These reactions are usually catalysed by dedicated Ppant transferases. Although rich in Ppant-dependent carrier proteins, it was previously shown that Pseudomonas aeruginosa possesses only one Ppant transferase, encoded by pcpS, which functions in both primary and secondary metabolism. Consistent with this notion are our findings that pcpS can genetically complement mutations in the Escherichia coli acpS and entD genes, encoding the apo-acyl carrier protein (ACP) synthase of fatty acid synthesis and a Ppant transferase of enterobactin synthesis, respectively. It also complements a Bacillus subtilis sfp mutation affecting a gene encoding a Ppant transferase essential for surfactin synthesis. A pcpS insertion mutant could only be constructed in a strain carrying the E. coli acpS gene on a chromosomally integrated element in trans, implying that the in vitro essentiality of pcpS is due to its requirement for activation of apo-ACP of fatty acid synthesis. The conditional pcpS mutant is non-fluorescent, does not produce pyoverdine and pyochelin, and does not grow in the presence of iron chelators. The data presented here for the first time confirm that PcpS plays an essential role in both fatty acid and siderophore metabolism.
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Seymour, Michelle L., David G. Binion, Steven J. Compton, Morley D. Hollenberg et Wallace K. MacNaughton. « Expression of proteinase-activated receptor 2 on human primary gastrointestinal myofibroblasts and stimulation of prostaglandin synthesis ». Canadian Journal of Physiology and Pharmacology 83, no 7 (1 juillet 2005) : 605–16. http://dx.doi.org/10.1139/y05-046.

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It is known that subepithelial myofibroblast-derived prostaglandin (PG)E2 can regulate intestinal epithelial cell functions, and that proteinase-activated receptor-2 (PAR2) is abundantly expressed in the gastrointestinal tract. Since PAR2 activation has previously been associated with stimulation of PGE2 synthesis, we hypothesized that PAR2 expressed on primary human gastrointestinal myofibroblasts regulates PGE2 synthesis via cyclooxygenase (COX)-1 and (or) COX-2, and associated PGE synthases. Primary human myofibroblasts were isolated from the resection tissue of the esophagus, small intestine, and colon. Expression of functional PAR2 was determined by RT-PCR and by calcium mobilization in Fura-2/AM-loaded cells. Trypsin and the selective PAR2-activating peptide (PAR2-AP) SLIGRL-NH2 stimulated PGE2 synthesis in a concentration-dependent manner, as measured by enzyme immunoassay. Selective COX inhibition showed PAR2-induced PGE2 synthesis to be COX-1 dependent in esophageal myofibroblasts and both COX-1 and COX-2 dependent in colonic cells, consistent with the distribution of COX-1 and COX-2 expression. Although both cytosolic and microsomal PGE synthases were expressed in cells from all tissues, microsomal PGE synthases were expressed at highest levels in the colonic myofibroblasts. Activation of PAR2 on gastrointestinal myofibroblasts stimulates PGE2 synthesis via different pathways in the colon than in the esophagus and small intestine. Key words: Proteinase-activated receptor, myofibroblast, cyclooxygenase, PGE synthase, prostaglandin E2, esophagus, small intestine, colon.
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Erben, Anne, Tom N. Grossmann et Oliver Seitz. « DNA‐gesteuerte Synthese und Bioaktivität proapoptotischer Peptide ». Angewandte Chemie 123, no 12 (21 février 2011) : 2880–84. http://dx.doi.org/10.1002/ange.201007103.

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Prieto, Carlos, Carlos García-Estrada, Diego Lorenzana et Juan Francisco Martín. « NRPSsp : non-ribosomal peptide synthase substrate predictor ». Bioinformatics 28, no 3 (29 novembre 2011) : 426–27. http://dx.doi.org/10.1093/bioinformatics/btr659.

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Kuznetsova, L. A. « Metabolic Syndrome : the Influence of Adipokines on the L-Arginine-NO Synthase-Nitric Oxide Signaling Pathway ». Acta Biomedica Scientifica 6, no 2 (24 juin 2021) : 22–40. http://dx.doi.org/10.29413/abs.2021-6.2.3.

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Metabolic syndrome includes the following symptoms: obesity, hyperlipidemia, hypertension, insulin resistance, and cardiovascular disease. The purpose of this review is to elucidate the role of adipokines in the regulation of the L-arginine-NO-synthas-NO signaling pathway in the pathogenesis of metabolic syndrome. The main questions raised in the review are: how adipokine secretion changes, how the level of their receptors is regulated, and which signaling pathways are involved in the transmission of adipokine signals when coupled to the L-arginine-NO-synthase-NO signaling cascade. Adipokines are peptide hormones that transmit a signal from adipose tissue to targets in the brain, blood vessels, liver, pancreas, muscles, and other tissues. Some adipokines have anti-inflammatory and insulin-sensitive effects: adiponectin, omentin, adipolin, chemerin, progranulin. Others have the negative inflammatory effect in the development ofmetabolic syndrome: visfatin, vaspin, apelin. Adipokines primarily regulate the expression and activity of endothelial NO-synthase. They either activate an enzyme involving 5-AMP protein kinase or Akt kinase, increasing its activity and synthesis of NO in the tissues of healthy patients: adiponectin, adipolin, omentin, or inhibit the activity of eNOS, which leads to a decrease in NO-synthase and suppression of mRNA bioavailability: vaspin, visfatin, apelin in metabolic syndrome, and a decrease in its activity leads to dissociation and endothelial dysfunction. It should be noted that the bioavailability of NO formed by NO-synthase is affected at many levels, including: the expression ofNO-synthase mRNA and its protein; the concentration of L-arginine; the level of cofactors of the reaction; and to detect the maximum activity of endothelial NO-synthase, dimerization of the enzyme is required, posttranslational modifications are important, in particular, phosphorylation of endothelial NO-synthase by serine 1177 with the participation of 5-AMP protein kinase, Akt kinase and other kinases. It should be noted that the participation of adiponectin, omentin, and kemerin in the regulation of the L-arginine-NO-synthase-NO cascade in metabolic syndrom opens up certain opportunities for the development of new approaches for the correction of disorders observed in this disease. The review analyzes the results of research searching in PubMed databases, starting from 2001 and up to 2020 using keywords and adipokine names, more than half of the references of the last 5 years.
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Wesener, Shane R., Vishwakanth Y. Potharla et Yi-Qiang Cheng. « Reconstitution of the FK228 Biosynthetic Pathway Reveals Cross Talk between Modular Polyketide Synthases and Fatty Acid Synthase ». Applied and Environmental Microbiology 77, no 4 (23 décembre 2010) : 1501–7. http://dx.doi.org/10.1128/aem.01513-10.

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ABSTRACTFunctional cross talk between fatty acid biosynthesis and secondary metabolism has been discovered in several cases in microorganisms; none of them, however, involves a modular biosynthetic enzyme. Previously, we reported a hybrid modular nonribosomal peptide synthetase (NRPS)-polyketide synthase (PKS) pathway for the biosynthesis of FK228 anticancer depsipeptide inChromobacterium violaceumstrain 968. This pathway contains two PKS modules on the DepBC enzymes that lack a functional acyltransferase (AT) domain, and no apparent AT-encoding gene exists within the gene cluster or its vicinity. We report here that, through reconstitution of the FK228 biosynthetic pathway inEscherichia colicells, two essential genes,fabD1andfabD2, both encoding a putative malonyl coenzyme A (CoA) acyltransferase component of the fatty acid synthase complex, are positively identified to be involved in FK228 biosynthesis. Either gene product appears sufficient to complement the AT-less PKS modules on DepBC for polyketide chain elongation. Concurrently, a gene (sfp) encoding a putative Sfp-type phosphopantetheinyltransferase was identified to be necessary for FK228 biosynthesis as well. Most interestingly, engineeredE. colistrains carrying variable genetic components produced significant levels of FK228 under both aerobic and anaerobic cultivation conditions. Discovery of thetranscomplementation of modular PKSs by housekeeping ATs reveals natural product biosynthesis diversity. Moreover, demonstration of anaerobic production of FK228 by an engineered facultative bacterial strain validates our effort toward the engineering of novel tumor-targeting bioagents.
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Zhu, H. B., D. Z. Guo, S. J. Yang, Y. H. Zhang, H. Wang, H. T. Guo, Y. Zhang et D. C. Cheng. « Osteogenic actions of the osteogenic growth peptide on bovine marrow mesenchymal stromal cells in culture ». Veterinární Medicína 53, No. 9 (16 octobre 2008) : 501–9. http://dx.doi.org/10.17221/1981-vetmed.

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The osteogenic growth peptide (OGP) regulates the differentiation of marrow mesenchymal stem cells derived from human and rodent cell lines into osteoblasts. Whether OGP directly regulates the bovine marrow mesenchymal stem cells differentiating into osteoblasts remains unknown. In this study, we evaluated the effects of OGP on the growth and differentiation of bovine marrow mesenchymal stem cells in culture. Our results showed that OGP promoted osteogenic differentiation of the bovine stem cells. OGP increased alkaline phosphatase (ALP) activity and mineralized nodule formation, and stimulated osteoblast-specific mRNA expression of Osteocalcin (BGP). On the other hand, OGP dose-dependently stimulated the expression of endothelial nitric oxide synthases. These results show for the first time a direct osteogenic effect of OGP on bovine marrow stromal cells in culture, which could be mediated by induction of endothelial nitric oxide synthases.
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Miyanaga, Akimasa, Fumitaka Kudo et Tadashi Eguchi. « Protein–protein interactions in polyketide synthase–nonribosomal peptide synthetase hybrid assembly lines ». Natural Product Reports 35, no 11 (2018) : 1185–209. http://dx.doi.org/10.1039/c8np00022k.

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Lansing, M., S. Lellig, A. Mausolf, I. Martini, F. Crescenzi, M. O'Regan et P. Prehm. « Hyaluronate synthase : cloning and sequencing of the gene from Streptococcus sp ». Biochemical Journal 289, no 1 (1 janvier 1993) : 179–84. http://dx.doi.org/10.1042/bj2890179.

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The complete nucleotide sequence of hyaluronate synthase from Streptococcus sp. and its flanking regions is presented. The gene locus was designated has. Southern-blotting results suggested that the gene was conserved in hyaluronate-producing streptococci. A putative translation-initiation codon was identified and the open reading frame consists of 1566 bp, specifying a protein of 56 kDa. Sequences resembling the promoter and ribosome-binding site of Gram-positive organisms are found upstream of the synthase. The predicted amino-acid sequence reveals the presence of a 35-residue signal peptide. The sequence has some similarity to bacterial peptide-binding proteins.
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Shashkin, P. N., Y. Jiao, H. Westerblad et A. Katz. « C-peptide does not alter carbohydrate metabolism in isolated mouse muscle ». American Journal of Physiology-Endocrinology and Metabolism 272, no 2 (1 février 1997) : E245—E247. http://dx.doi.org/10.1152/ajpendo.1997.272.2.e245.

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The effects of C-peptide on carbohydrate metabolism in isolated mouse soleus muscle were studied. C-peptide, at concentrations up to 1,000 nM, had no effect on [14C]glucose incorporation into glycogen, glycogen synthase activity, or 2-deoxyglucose uptake. These data demonstrate that C-peptide has no direct effect on the measured parameters of carbohydrate metabolism in isolated mouse muscle.
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Maurin, Ophélie, Pascal Verdié, Gilles Subra, Frédéric Lamaty, Jean Martinez et Thomas-Xavier Métro. « Peptide synthesis : ball-milling, in solution, or on solid support, what is the best strategy ? » Beilstein Journal of Organic Chemistry 13 (6 octobre 2017) : 2087–93. http://dx.doi.org/10.3762/bjoc.13.206.

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While presenting particularly interesting advantages, peptide synthesis by ball-milling was never compared to the two traditional strategies, namely peptide syntheses in solution and on solid support (solid-phase peptide synthesis, SPPS). In this study, the challenging VVIA tetrapeptide was synthesized by ball-milling, in solution, and on solid support. The three strategies were then compared in terms of yield, purity, reaction time and environmental impact. The results obtained enabled to draw some strengths and weaknesses of each strategy, and to foresee what will have to be implemented to build more efficient and sustainable peptide syntheses in the near future.
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Zhu, Peng, Yanling Zheng, Yurong You, Xiaojun Yan et Jianzhong Shao. « Sequencing and modular analysis of the hybrid non-ribosomal peptide synthase – polyketide synthase gene cluster from the marine sponge Hymeniacidon perleve-associated bacterium Pseudoalteromonas sp. strain NJ631 ». Canadian Journal of Microbiology 55, no 3 (mars 2009) : 219–27. http://dx.doi.org/10.1139/w08-125.

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In the present study, we sought to confirm a putative non-ribosomal peptide synthase (NRPS) – polyketide synthase (PKS) gene cluster in marine sponge–associated bacterium with cytotoxic activity and elucidate the gene’s structural information. The genomic library of the marine sponge Hymeniacidon perleve –associated bacterium Pseudoalteromonas sp. strain NJ631 was constructed using a pCC1FOS fosmid. Positive clones that covered the whole gene cluster region of hybrid NRPS–PKS were selected for shotgun sequencing. The results obtained from BlastX and open reading frame (ORF) analysis indicated that there are 3 big ORFs, NJA1, NJA2, and NJA3, that encoded proteins with similarities to amino acid adenylation, β-ketoacyl synthase, and non-ribosomal peptide synthase, respectively, from different organisms. The results gave us a clue that there could be PKS or NRPS modules in the 3 ORFs. Further analysis demonstrated 3 ORFs encoding 2 NRPS modules, 1 PKS module, and 3 NRPS modules. Using the specificity-conferring selection rule, the substrate specificity of 4 adenylation (A) domains (A2, A3, A4, and A5) were successfully predicted, and the amino acids of the substrate specificity were glutamic acid – glutamine, serine, d-serine, and Aeo (2-amino-9,10-epoxy-8-oxodecanoic acid), respectively.
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Urbaniak, Monika, Agnieszka Waśkiewicz, Artur Trzebny, Grzegorz Koczyk et Łukasz Stępień. « Cyclodepsipeptide Biosynthesis in Hypocreales Fungi and Sequence Divergence of The Non-Ribosomal Peptide Synthase Genes ». Pathogens 9, no 7 (9 juillet 2020) : 552. http://dx.doi.org/10.3390/pathogens9070552.

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Fungi from the Hypocreales order synthesize a range of toxic non-ribosomal cyclic peptides with antimicrobial, insecticidal and cytotoxic activities. Entomopathogenic Beauveria, Isaria and Cordyceps as well as phytopathogenic Fusarium spp. are known producers of beauvericins (BEAs), beauvenniatins (BEAEs) or enniatins (ENNs). The compounds are synthesized by beauvericin/enniatin synthase (BEAS/ESYN1), which shows significant sequence divergence among Hypocreales members. We investigated ENN, BEA and BEAE production among entomopathogenic (Beauveria, Cordyceps, Isaria) and phytopathogenic (Fusarium) fungi; BEA and ENNs were quantified using an LC-MS/MS method. Phylogenetic analysis of partial sequences of putative BEAS/ESYN1 amplicons was also made. Nineteen fungal strains were identified based on sequence analysis of amplified ITS and tef-1α regions. BEA was produced by all investigated fungi, with F. proliferatum and F. concentricum being the most efficient producers. ENNs were synthesized mostly by F. acuminatum, F. avenaceum and C. confragosa. The phylogeny reconstruction suggests that ancestral BEA biosynthesis independently diverged into biosynthesis of other compounds. The divergent positioning of three Fusarium isolates raises the possibility of parallel acquisition of cyclic depsipeptide synthases in ancient complexes within Fusarium genus. Different fungi have independently evolved NRPS genes involved in depsipeptide biosynthesis, with functional adaptation towards biosynthesis of overlapping yet diversified metabolite profiles.
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García-Estrada, Carlos, Ricardo V. Ullán, Tania Velasco-Conde, Ramiro P. Godio, Fernando Teijeira, Inmaculada Vaca, Raúl Feltrer, Katarina Kosalková, Elba Mauriz et Juan F. Martín. « Post-translational enzyme modification by the phosphopantetheinyl transferase is required for lysine and penicillin biosynthesis but not for roquefortine or fatty acid formation in Penicillium chrysogenum ». Biochemical Journal 415, no 2 (25 septembre 2008) : 317–24. http://dx.doi.org/10.1042/bj20080369.

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NRPSs (non-ribosomal peptide synthetases) and PKSs (polyketide synthases) require post-translational phosphopantetheinylation to become active. This reaction is catalysed by a PPTase (4′-phosphopantetheinyl transferase). The ppt gene of Penicillium chrysogenum, encoding a protein that shares 50% similarity with the stand-alone large PPTases, has been cloned. This gene is present as a single copy in the genome of the wild-type and high-penicillin-producing strains (containing multiple copies of the penicillin gene cluster). Amplification of the ppt gene produced increases in isopenicillin N and benzylpenicillin biosynthesis. A PPTase-defective mutant (Wis54-PPT−) was obtained. It required lysine and lacked pigment and penicillin production, but it still synthesized normal levels of roquefortine. The biosynthesis of roquefortine does not appear to involve PPTase-mediated modification of the synthesizing enzymes. The PPT− mutant did not require fatty acids, which indicates that activation of the fatty acid synthase is performed by a different PPTase. Complementation of Wis54-PPT− with the ppt gene restored lysine biosynthesis, pigmentation and penicillin production, which demonstrates the wide range of processes controlled by this gene.
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Fyfe, Paul K., Gareth D. Westrop, Tania Ramos, Sylke Müller, Graham H. Coombs et William N. Hunter. « Structure ofLeishmania majorcysteine synthase ». Acta Crystallographica Section F Structural Biology and Crystallization Communications 68, no 7 (22 juin 2012) : 738–43. http://dx.doi.org/10.1107/s1744309112019124.

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Cysteine biosynthesis is a potential target for drug development against parasiticLeishmaniaspecies; these protozoa are responsible for a range of serious diseases. To improve understanding of this aspect ofLeishmaniabiology, a crystallographic and biochemical study ofL. majorcysteine synthase has been undertaken, seeking to understand its structure, enzyme activity and modes of inhibition. Active enzyme was purified, assayed and crystallized in an orthorhombic form with a dimer in the asymmetric unit. Diffraction data extending to 1.8 Å resolution were measured and the structure was solved by molecular replacement. A fragment of γ-poly-D-glutamic acid, a constituent of the crystallization mixture, was bound in the enzyme active site. Although a D-glutamate tetrapeptide had insignificant inhibitory activity, the enzyme was competitively inhibited (Ki= 4 µM) by DYVI, a peptide based on the C-terminus of the partner serine acetyltransferase with which the enzyme forms a complex. The structure surprisingly revealed that the cofactor pyridoxal phosphate had been lost during crystallization.
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Yun, Choong-Soo, Kazuki Nishimoto, Takayuki Motoyama, Takeshi Shimizu, Tomoya Hino, Naoshi Dohmae, Shingo Nagano et Hiroyuki Osada. « Unique features of the ketosynthase domain in a nonribosomal peptide synthetase–polyketide synthase hybrid enzyme, tenuazonic acid synthetase 1 ». Journal of Biological Chemistry 295, no 33 (21 juin 2020) : 11602–12. http://dx.doi.org/10.1074/jbc.ra120.013105.

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Many microbial secondary metabolites are produced by multienzyme complexes comprising nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). The ketosynthase (KS) domains of polyketide synthase normally catalyze the decarboxylative Claisen condensation of acyl and malonyl blocks to extend the polyketide chain. However, the terminal KS domain in tenuazonic acid synthetase 1 (TAS1) from the fungus Pyricularia oryzae conducts substrate cyclization. Here, we report on the unique features of the KS domain in TAS1. We observed that this domain is monomeric, not dimeric as is typical for KSs. Analysis of a 1.68-Å resolution crystal structure suggests that the substrate cyclization is triggered via proton abstraction from the active methylene moiety in the substrate by a catalytic His-322 residue. Additionally, we show that TAS1 KS promiscuously accepts aminoacyl substrates and that this promiscuity can be increased by a single amino acid substitution in the substrate-binding pocket of the enzyme. These findings provide insight into a KS domain that accepts the amino acid–containing substrate in an NRPS–PKS hybrid enzyme and provide hints to the substrate cyclization mechanism performed by the KS domain in the biosynthesis of the mycotoxin tenuazonic acid.
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Hebecker, Stefanie, Joern Krausze, Tatjana Hasenkampf, Julia Schneider, Maike Groenewold, Joachim Reichelt, Dieter Jahn, Dirk W. Heinz et Jürgen Moser. « Structures of two bacterial resistance factors mediating tRNA-dependent aminoacylation of phosphatidylglycerol with lysine or alanine ». Proceedings of the National Academy of Sciences 112, no 34 (10 août 2015) : 10691–96. http://dx.doi.org/10.1073/pnas.1511167112.

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The cytoplasmic membrane is probably the most important physical barrier between microbes and the surrounding habitat. Aminoacylation of the polar head group of the phospholipid phosphatidylglycerol (PG) catalyzed by Ala-tRNAAla–dependent alanyl-phosphatidylglycerol synthase (A-PGS) or by Lys-tRNALys–dependent lysyl-phosphatidylglycerol synthase (L-PGS) enables bacteria to cope with cationic peptides that are harmful to the integrity of the cell membrane. Accordingly, these synthases also have been designated as multiple peptide resistance factors (MprF). They consist of a separable C-terminal catalytic domain and an N-terminal transmembrane flippase domain. Here we present the X-ray crystallographic structure of the catalytic domain of A-PGS from the opportunistic human pathogen Pseudomonas aeruginosa. In parallel, the structure of the related lysyl-phosphatidylglycerol–specific L-PGS domain from Bacillus licheniformis in complex with the substrate analog L-lysine amide is presented. Both proteins reveal a continuous tunnel that allows the hydrophobic lipid substrate PG and the polar aminoacyl-tRNA substrate to access the catalytic site from opposite directions. Substrate recognition of A-PGS versus L-PGS was investigated using misacylated tRNA variants. The structural work presented here in combination with biochemical experiments using artificial tRNA or artificial lipid substrates reveals the tRNA acceptor stem, the aminoacyl moiety, and the polar head group of PG as the main determinants for substrate recognition. A mutagenesis approach yielded the complementary amino acid determinants of tRNA interaction. These results have broad implications for the design of L-PGS and A-PGS inhibitors that could render microbial pathogens more susceptible to antimicrobial compounds.
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Acitores, A., N. Gonzalez, V. Sancho, I. Valverde et ML Villanueva-Penacarrillo. « Cell signalling of glucagon-like peptide-1 action in rat skeletal muscle ». Journal of Endocrinology 180, no 3 (1 mars 2004) : 389–98. http://dx.doi.org/10.1677/joe.0.1800389.

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Glucagon-like peptide-1 (GLP-1), an incretin with glucose-dependent insulinotropic and insulin-independent antidiabetic properties, has insulin-like effects on glucose metabolism in extrapancreatic tissues participating in overall glucose homeostasis. These effects are exerted through specific receptors not associated with cAMP, an inositol phosphoglycan being a possible second messenger. In rat hepatocytes, activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB), protein kinase C (PKC) and protein phosphatase 1 (PP-1) has been shown to be involved in the GLP-1-induced stimulation of glycogen synthase. We have investigated the role of enzymes known or suggested to mediate the actions of insulin in the GLP-1-induced increase in glycogen synthase a activity in rat skeletal muscle strips. We first explored the effect of GLP-1, compared with that of insulin, on the activation of PI3K, PKB, p70s6 kinase (p70s6k) and p44/42 mitogen-activated protein kinases (MAPKs) and the action of specific inhibitors of these kinases on the insulin- and GLP-1-induced increment in glycogen synthase a activity. The study showed that GLP-1, like insulin, activated PI3K/PKB, p70s6k and p44/42. Wortmannin (a PI3K inhibitor) reduced the stimulatory action of insulin on glycogen synthase a activity and blocked that of GLP-1, rapamycin (a 70s6k inhibitor) did not affect the action of GLP-1 but abolished that of insulin, PD98059 (MAPK inhibitor) was ineffective on insulin but blocked the action of GLP-1, okadaic acid (a PP-2A inhibitor) and tumour necrosis factor-alpha (a PP-1 inhibitor) were both ineffective on GLP-1 but abolished the action of insulin, and Ro 31-8220 (an inhibitor of some PKC isoforms) reduced the effect of GLP-1 while completely preventing that of insulin. It was concluded that activation of PI3K/PKB and MAPKs is required for the GLP-1-induced increment in glycogen synthase a activity, while PKC, although apparently participating, does not seem to play an essential role; unlike in insulin signaling, p70s6k, PP-1 and PP-2A do not seem to be needed in the action of GLP-1 upon glycogen synthase a activity in rat muscle.
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Drulyte, Ieva, Jana Obajdin, Chi H. Trinh, Arnout P. Kalverda, Marc W. van der Kamp, Glyn R. Hemsworth et Alan Berry. « Crystal structure of the putative cyclase IdmH from the indanomycin nonribosomal peptide synthase/polyketide synthase ». IUCrJ 6, no 6 (24 octobre 2019) : 1120–33. http://dx.doi.org/10.1107/s2052252519012399.

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Indanomycin is biosynthesized by a hybrid nonribosomal peptide synthase/polyketide synthase (NRPS/PKS) followed by a number of `tailoring' steps to form the two ring systems that are present in the mature product. It had previously been hypothesized that the indane ring of indanomycin was formed by the action of IdmH using a Diels–Alder reaction. Here, the crystal structure of a selenomethionine-labelled truncated form of IdmH (IdmH-Δ99–107) was solved using single-wavelength anomalous dispersion (SAD) phasing. This truncated variant allows consistent and easy crystallization, but importantly the structure was used as a search model in molecular replacement, allowing the full-length IdmH structure to be determined to 2.7 Å resolution. IdmH is a homodimer, with the individual protomers consisting of an α+β barrel. Each protomer contains a deep hydrophobic pocket which is proposed to constitute the active site of the enzyme. To investigate the reaction catalysed by IdmH, 88% of the backbone NMR resonances were assigned, and using chemical shift perturbation of [15N]-labelled IdmH it was demonstrated that indanomycin binds in the active-site pocket. Finally, combined quantum mechanical/molecular mechanical (QM/MM) modelling of the IdmH reaction shows that the active site of the enzyme provides an appropriate environment to promote indane-ring formation, supporting the assignment of IdmH as the key Diels–Alderase catalysing the final step in the biosynthesis of indanomycin through a similar mechanism to other recently characterized Diels–Alderases involved in polyketide-tailoring reactions. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at https://proteopedia.org/w/Journal:IUCrJ:S2052252519012399.
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Li, Y. M., J. C. Milne, L. L. Madison, R. Kolter et C. T. Walsh. « From Peptide Precursors to Oxazole and Thiazole-Containing Peptide Antibiotics : Microcin B17 Synthase ». Science 274, no 5290 (15 novembre 1996) : 1188–93. http://dx.doi.org/10.1126/science.274.5290.1188.

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27

Kant, V., G. Sahoo, M. Kumar, M. Dikhit, S. Sinha et P. Das. « Designing of Peptide and Non-Peptide Inhibitors against Leishmania Cysteine-Synthase (Ld-OASS) ». International Journal of Infectious Diseases 73 (août 2018) : 301. http://dx.doi.org/10.1016/j.ijid.2018.04.4100.

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Dreyfus, JC. « Un peptide de synthèse inhibe les métastases du mélanome de souris ». médecine/sciences 2, no 10 (1986) : 586. http://dx.doi.org/10.4267/10608/3432.

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Wilhelm, B., P. Kann et A. Pfützner. « Influence of C-Peptide on Glucose Utilisation ». Experimental Diabetes Research 2008 (2008) : 1–3. http://dx.doi.org/10.1155/2008/769483.

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During the recent years, multiple studies demonstrated that C-peptide is not an inert peptide, but exerts important physiological effects. C-peptide binds to cell membranes, stimulates the Na,K-ATPase and the endothelial nitric oxide (NO) synthase. Moreover, there is evidence that C-peptide decreases glomerular hyperfiltration and increases glucose utilisation. Nevertheless, there is still limited knowledge concerning mechanisms leading to an increased glucose utilisation either in rats or in humans. The aim of this paper is to give an overview over the published studies regarding C-peptide and glucose metabolism from in vitro studies to longer lasting studies in humans.
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PÉREZ, Mar, Ana I. ROJO, Francisco WANDOSELL, Javier DÍAZ-NIDO et Jesús AVILA. « Prion peptide induces neuronal cell death through a pathway involving glycogen synthase kinase 3 ». Biochemical Journal 372, no 1 (15 mai 2003) : 129–36. http://dx.doi.org/10.1042/bj20021596.

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Prion diseases are characterized by neuronal cell death, glial proliferation and deposition of prion peptide aggregates. An abnormal misfolded isoform of the prion protein (PrP) is considered to be responsible for this neurodegeneration. The PrP 106–126, a synthetic peptide obtained from the amyloidogenic region of the PrP, constitutes a model system to study prion-induced neurodegeneration as it retains the ability to trigger cell death in neuronal cultures. In the present study, we show that the addition of this prion peptide to cultured neurons increases the activity of glycogen synthase kinase 3 (GSK-3), which is accompanied by the enhanced phosphorylation of some microtubule-associated proteins including tau and microtubule-associated protein 2. Prion peptide-treated neurons become progressively atrophic, and die ultimately. Both lithium and insulin, which inhibit GSK-3 activity, significantly decrease prion peptide-induced cell death both in primary neuronal cultures and in neuroblastoma cells. Finally, the overexpression of a dominant-negative mutant of GSK-3 in transfected neuroblastoma cells efficiently prevents prion peptide-induced cell death. These results are consistent with the view that the activation of GSK-3 is a crucial mediator of prion peptide-induced neurodegeneration.
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31

Nguyen, Tiffany T., Mourad Ogbi, Qilin Yu et John A. Johnson. « Attenuation of the hypoxia-induced protein kinase Cδ interaction with the ‘d’ subunit of F1Fo-ATP synthase in neonatal cardiac myocytes : implications for energy preservation and survival ». Biochemical Journal 429, no 2 (28 juin 2010) : 335–45. http://dx.doi.org/10.1042/bj20091927.

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The F1Fo-ATP synthase provides most of the heart's energy, yet events that alter its function during injury are poorly understood. Recently, we described a potent inhibitory effect on F1Fo-ATP synthase function mediated by the interaction of PKCδ (protein kinase Cδ) with dF1Fo (‘d’ subunit of the F1Fo-ATPase/ATP synthase). We have now developed novel peptide modulators which facilitate or inhibit the PKCδ–dF1Fo interaction. These peptides include HIV-Tat (transactivator of transcription) protein transduction and mammalian mitochondrial-targeting sequences. Pre-incubation of NCMs (neonatal cardiac myocyte) with 10 nM extracellular concentrations of the mitochondrial-targeted PKCδ–dF1Fo interaction inhibitor decreased Hx (hypoxia)-induced co-IP (co-immunoprecipitation) of PKCδ with dF1Fo by 40±9%, abolished Hx-induced inhibition of F1Fo-ATPase activity, attenuated Hx-induced losses in F1Fo-derived ATP and protected against Hx- and reperfusion-induced cell death. A scrambled-sequence (inactive) peptide, which contained HIV-Tat and mitochondrial-targeting sequences, was without effect. In contrast, the cell-permeant mitochondrial-targeted PKCδ–dF1Fo facilitator peptide, which we have shown previously to induce the PKCδ–dF1Fo co-IP, was found to inhibit F1Fo-ATPase activity to an extent similar to that caused by Hx alone. The PKCδ–dF1Fo facilitator peptide also decreased ATP levels by 72±18% under hypoxic conditions in the presence of glycolytic inhibition. None of the PKCδ–dF1Fo modulatory peptides altered the inner mitochondrial membrane potential. Our studies provide the first evidence that disruption of the PKCδ–dF1Fo interaction using cell-permeant mitochondrial-targeted peptides attenuates cardiac injury resulting from prolonged oxygen deprivation.
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Kakule, Thomas B., Zhenjian Lin et Eric W. Schmidt. « Combinatorialization of Fungal Polyketide Synthase–Peptide Synthetase Hybrid Proteins ». Journal of the American Chemical Society 136, no 51 (8 décembre 2014) : 17882–90. http://dx.doi.org/10.1021/ja511087p.

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Wagner, Holger, Klaus Harms, Ulrich Koert, Sabine Meder et Günther Boheim. « Oligo-THF-Peptide : Synthese, Membraneinbau und Untersuchungen zur Ionenkanalaktivität ». Angewandte Chemie 108, no 22 (18 novembre 1996) : 2836–39. http://dx.doi.org/10.1002/ange.19961082228.

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34

RIVEROS-MORENO, Valentina, Christopher BEDDELL et Salvador MONCADA. « Nitric oxide synthase. Structural studies using anti-peptide antibodies ». European Journal of Biochemistry 215, no 3 (août 1993) : 801–8. http://dx.doi.org/10.1111/j.1432-1033.1993.tb18095.x.

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35

Rea, Philip A. « Phytochelatin synthase : of a protease a peptide polymerase made ». Physiologia Plantarum 145, no 1 (5 mars 2012) : 154–64. http://dx.doi.org/10.1111/j.1399-3054.2012.01571.x.

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36

Cook, H. Terence, Alison J. Bune, Albertine S. Jansen, G. Michael Taylor, Rashpal K. Loi et Victoria Cattell. « Cellular Localization of Inducible Nitric Oxide Synthase in Experimental Endotoxic Shock in the Rat ». Clinical Science 87, no 2 (1 août 1994) : 179–86. http://dx.doi.org/10.1042/cs0870179.

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1. Endotoxin induces a shock-like syndrome with increased nitric oxide synthesis. To clarify the cellular source of NO in endotoxic shock we used immunohistochemistry and in situ hybridization to localize inducible NO synthase in rats given lipopolysaccharide or Corynebacterium parvum and lipopolysaccharide. Immunohistochemistry was carried out with an antibody raised against a synthetic peptide of mouse macrophage NO synthase. In situ hybridization was performed with 35S-labelled oligonucleotide probes corresponding to cDNA sequences common to mouse macrophage inducible NO synthase and rat vascular smooth inducible NO synthase. Monocytes and macrophages were identified by immunohistochemistry with the mouse monoclonal antibody ED1. 2. After lipopolysaccharide alone, the major site of NO synthase induction was monocytes and macrophages in multiple organs, principally liver and spleen. Bronchial, bile duct, intestinal and bladder epithelium and some hepatocytes also expressed inducible NO synthase. Expression peaked at 5 h and had returned to normal by 12 h except in spleen. 3. After priming with C. parvum, lipopolysaccharide led to a similar distribution of inducible NO synthase as lipopolysaccharide alone, but in addition there was more prominent hepatocyte staining, staining in macrophage granulomas in the liver and inducible NO synthase was present in some endothelial cells in the aorta. 4. These findings provide a direct demonstration of the cellular localization of inducible NO synthase after lipopolysaccharide.
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37

Williams, Gavin J. « Engineering polyketide synthases and nonribosomal peptide synthetases ». Current Opinion in Structural Biology 23, no 4 (août 2013) : 603–12. http://dx.doi.org/10.1016/j.sbi.2013.06.012.

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Bendlová, Běla, Michal Lebl, Pavel Štolba et Luboslav Stárka. « Synthesis of modified human C-peptide and its fragments ». Collection of Czechoslovak Chemical Communications 53, no 11 (1988) : 2637–44. http://dx.doi.org/10.1135/cccc19882637.

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Syntheses of the modified human C-peptide containing residues suitable for the introduction of the radioactive label (tyrosine) and internal marker for monitoring binding to carrier (norvaline) and five of its fragments are described. The syntheses were performed by solid phase method using either 9-fluorenylmethoxycarbonyl or tert-butyloxycarbonyl protecting groups. The products were purified by gel filtration, ion exchange chromatography and reversed phase HPLC. The reactivity of prepared peptides with antisera was determined and the modified C-peptide was found fully reactive.
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39

Fewer, David P., Julia Österholm, Leo Rouhiainen, Jouni Jokela, Matti Wahlsten et Kaarina Sivonen. « Nostophycin Biosynthesis Is Directed by a Hybrid Polyketide Synthase-Nonribosomal Peptide Synthetase in the Toxic Cyanobacterium Nostoc sp. Strain 152 ». Applied and Environmental Microbiology 77, no 22 (23 septembre 2011) : 8034–40. http://dx.doi.org/10.1128/aem.05993-11.

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ABSTRACTCyanobacteria are a rich source of natural products with interesting pharmaceutical properties. Here, we report the identification, sequencing, annotation, and biochemical analysis of the nostophycin (npn) biosynthetic gene cluster. Thenpngene cluster spans 45.1 kb and consists of three open reading frames encoding a polyketide synthase, a mixed polyketide nonribosomal peptide synthetase, and a nonribosomal peptide synthetase. The genetic architecture and catalytic domain organization of the proteins are colinear in arrangement, with the putative order of the biosynthetic assembly of the cyclic heptapeptide. NpnB contains an embedded monooxygenase domain linking nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) catalytic domains and predicted here to hydroxylate the nostophycin during assembly. Expression of the adenylation domains and subsequent substrate specificity assays support the involvement of this cluster in nostophycin biosynthesis. Biochemical analyses suggest that the loading substrate of NpnA is likely to be a phenylpropanoic acid necessitating deletion of a carbon atom to explain the biosynthesis of nostophycin. Biosyntheses of nostophycin and microcystin resemble each other, but the phylogenetic analyses suggest that they are distantly related to one another.
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Pacifico, Salvatore, Matteo Santucci, Rosaria Luciani, Puneet Saxena, Pasquale Linciano, Glauco Ponterini, Angela Lauriola et al. « Cyclic Peptides Acting as Allosteric Inhibitors of Human Thymidylate Synthase and Cancer Cell Growth ». Molecules 24, no 19 (26 septembre 2019) : 3493. http://dx.doi.org/10.3390/molecules24193493.

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Thymidylate synthase (TS) is a prominent drug target for different cancer types. However, the prolonged use of its classical inhibitors, substrate analogs that bind at the active site, leads to TS overexpression and drug resistance in the clinic. In the effort to identify anti-TS drugs with new modes of action and able to overcome platinum drug resistance in ovarian cancer, octapeptides with a new allosteric inhibition mechanism were identified as cancer cell growth inhibitors that do not cause TS overexpression. To improve the biological properties, 10 cyclic peptides (cPs) were designed from the lead peptides and synthesized. The cPs were screened for the ability to inhibit recombinant human thymidylate synthase (hTS), and peptide 7 was found to act as an allosteric inhibitor more potent than its parent open-chain peptide [Pro3]LR. In cytotoxicity studies on three human ovarian cancer cell lines, IGROV-1, A2780, and A2780/CP, peptide 5 and two other cPs, including 7, showed IC50 values comparable with those of the reference drug 5-fluorouracil, of the open-chain peptide [d-Gln4]LR, and of another seven prolyl derivatives of the lead peptide LR. These promising results indicate cP 7 as a possible lead compound to be chemically modified with the aim of improving both allosteric TS inhibitory activity and anticancer effectiveness.
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41

Lee, Bee-Na, Scott Kroken, David Y. T. Chou, Barbara Robbertse, O. C. Yoder et B. Gillian Turgeon. « Functional Analysis of All Nonribosomal Peptide Synthetases in Cochliobolus heterostrophus Reveals a Factor, NPS6, Involved in Virulence and Resistance to Oxidative Stress ». Eukaryotic Cell 4, no 3 (mars 2005) : 545–55. http://dx.doi.org/10.1128/ec.4.3.545-555.2005.

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ABSTRACT Nonribosomal peptides, made by nonribosomal peptide synthetases, have diverse biological activities, including roles as fungal virulence effectors. Inspection of the genome of Cochliobolus heterostrophus, a fungal pathogen of maize and a member of a genus noted for secondary metabolite production, revealed eight multimodular nonribosomal peptide synthase (NPS) genes and three monomodular NPS-like genes, one of which encodes a nonribosomal peptide synthetase/polyketide synthase hybrid enzyme presumed to be involved in synthesis of a peptide/polyketide molecule. Deletion of each NPS gene and phenotypic analyses showed that the product of only one of these genes, NPS6, is required for normal virulence on maize. NPS6 is also required for resistance to hydrogen peroxide, suggesting it may protect the fungus from oxidative stress. This and all other nps mutants had normal growth, mating ability, and appressoria. Real-time PCR analysis showed that expression of all NPS genes is low (relative to that of actin), that all (except possibly NPS2) are expressed during vegetative growth, and that expression is induced by nitrogen starvation. Only NPS6 is unfailingly conserved among euascomycete fungi, including plant and human pathogens and saprobes, suggesting the possibility that NPS6 activity provides oxidative stress protection during both saprobic and parasitic growth.
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42

Darcel, Laurine, Sanjit Das, Isabelle Bonnard, Bernard Banaigs et Nicolas Inguimbert. « Thirtieth Anniversary of the Discovery of Laxaphycins. Intriguing Peptides Keeping a Part of Their Mystery ». Marine Drugs 19, no 9 (24 août 2021) : 473. http://dx.doi.org/10.3390/md19090473.

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Lipopeptides are a class of compounds generally produced by microorganisms through hybrid biosynthetic pathways involving non-ribosomal peptide synthase and a polyketyl synthase. Cyanobacterial-produced laxaphycins are examples of this family of compounds that have expanded over the past three decades. These compounds benefit from technological advances helping in their synthesis and characterization, as well as in deciphering their biosynthesis. The present article attempts to summarize most of the articles that have been published on laxaphycins. The current knowledge on the ecological role of these complex sets of compounds will also be examined.
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43

Luque, MA, N. Gonzalez, L. Marquez, A. Acitores, A. Redondo, M. Morales, I. Valverde et ML Villanueva-Penacarrillo. « Glucagon-like peptide-1 (GLP-1) and glucose metabolism in human myocytes ». Journal of Endocrinology 173, no 3 (1 juin 2002) : 465–73. http://dx.doi.org/10.1677/joe.0.1730465.

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Glucagon-like peptide-1 (GLP-1) has been shown to have insulin-like effects upon the metabolism of glucose in rat liver, muscle and fat, and on that of lipids in rat and human adipocytes. These actions seem to be exerted through specific receptors which, unlike that of the pancreas, are not - at least in liver and muscle - cAMP-associated. Here we have investigated the effect, its characteristics, and possible second messengers of GLP-1 on the glucose metabolism of human skeletal muscle, in tissue strips and primary cultured myocytes. In muscle strips, GLP-1, like insulin, stimulated glycogen synthesis, glycogen synthase a activity, and glucose oxidation and utilization, and inhibited glycogen phosphorylase a activity, all of this at physiological concentrations of the peptide. In cultured myotubes, GLP-1 exerted, from 10(-13) mol/l, a dose-related increase of the D-[U-(14)C]glucose incorporation into glycogen, with the same potency as insulin, together with an activation of glycogen synthase a; the effect of 10(-11) mol/l GLP-1 on both parameters was additive to that induced by the equimolar amount of insulin. Synthase a was still activated in cells after 2 days of exposure to GLP-1, as compared with myotubes maintained in the absence of peptide. In human muscle cells, exendin-4 and its truncated form 9-39 amide (Ex-9) are both agonists of the GLP-1 effect on glycogen synthesis and synthase a activity; but while neither GLP-1 nor exendin-4 affected the cellular cAMP content after 5-min incubation in the absence of 3-isobutyl-1-methylxantine (IBMX), an increase was detected with Ex-9. GLP-1, exendin-4, Ex-9 and insulin all induced the prompt hydrolysis of glycosylphosphatidylinositols (GPIs). This work shows a potent stimulatory effect of GLP-1 on the glucose metabolism of human skeletal muscle, and supports the long-term therapeutic value of the peptide. Further evidence for a GLP-1 receptor in this tissue, different from that of the pancreas, is also illustrated, suggesting a role for an inositolphosphoglycan (IPG) as at least one of the possible second messengers of the GLP-1 action in human muscle.
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Ross, S. « Synthèse et activité antinéoplastique de dérivés alanyl-2-glycyl peptide de nocodazole ». European Journal of Medicinal Chemistry 24, no 4 (août 1989) : 363–70. http://dx.doi.org/10.1016/0223-5234(89)90079-2.

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45

Urbaniak, Monika, Agnieszka Waśkiewicz, Grzegorz Koczyk, Lidia Błaszczyk et Łukasz Stępień. « Divergence of Beauvericin Synthase Gene among Fusarium and Trichoderma Species ». Journal of Fungi 6, no 4 (15 novembre 2020) : 288. http://dx.doi.org/10.3390/jof6040288.

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Beauvericin (BEA) is a cyclodepsipeptide mycotoxin, showing insecticidal, antibiotic and antimicrobial activities, as well as inducing apoptosis of cancer cell lines. BEA can be produced by multiple fungal species, including saprotrophs, plant, insect and human pathogens, particularly belonging to Fusarium, Beauveria and Isaria genera. The ability of Trichoderma species to produce BEA was until now uncertain. Biosynthesis of BEA is governed by a non-ribosomal peptide synthase (NRPS), known as beauvericin synthase (BEAS), which appears to present considerable divergence among different fungal species. In the present study we compared the production of beauvericin among Fusarium and Trichoderma strains using UPLC methods. BEAS fragments were sequenced and analyzed to examine the level of the gene’s divergence between these two genera and confirm the presence of active BEAS copy in Trichoderma. Seventeen strains of twelve species were studied and phylogenetic analysis showed distinctive grouping of Fusarium and Trichoderma strains. The highest producers of beauvericin were F. proliferatum and F. nygamai. Trichoderma strains of three species (T. atroviride, T. viride, T. koningiopsis) were minor BEA producers. The study showed beauvericin production by Fusarium and Trichoderma species and high variance of the non-ribosomal peptide synthase gene among fungal species from the Hypocreales order.
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Kers, Johan A., Michael J. Wach, Stuart B. Krasnoff, Joanne Widom, Kimberly D. Cameron, Raghida A. Bukhalid, Donna M. Gibson, Brian R. Crane et Rosemary Loria. « Nitration of a peptide phytotoxin by bacterial nitric oxide synthase ». Nature 429, no 6987 (mai 2004) : 79–82. http://dx.doi.org/10.1038/nature02504.

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47

Wallerath, Thomas, Thomas Kunt, Thomas Forst, Ellen I. Closs, Ralf Lehmann, Thomas Flohr, Matthias Gabriel et al. « Stimulation of endothelial nitric oxide synthase by proinsulin C-peptide ». Nitric Oxide 9, no 2 (septembre 2003) : 95–102. http://dx.doi.org/10.1016/j.niox.2003.08.004.

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Censarek, Petra, Michael Beyermann et Karl-Wilhelm Koch. « Thermodynamics of apocalmodulin and nitric oxide synthase II peptide interaction ». FEBS Letters 577, no 3 (30 octobre 2004) : 465–68. http://dx.doi.org/10.1016/j.febslet.2004.10.048.

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Seguin, Jérôme, Mireille Moutiez, Yan Li, Pascal Belin, Alain Lecoq, Matthieu Fonvielle, Jean-Baptiste Charbonnier, Jean-Luc Pernodet et Muriel Gondry. « Nonribosomal Peptide Synthesis in Animals : The Cyclodipeptide Synthase of Nematostella ». Chemistry & ; Biology 18, no 11 (novembre 2011) : 1362–68. http://dx.doi.org/10.1016/j.chembiol.2011.09.010.

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Voeller, Donna M., Maria Zajac-Kaye, Robert J. Fisher et Carmen J. Allegra. « The identification of thymidylate synthase peptide domains located in the interface region that bind thymidylate synthase mRNA ». Biochemical and Biophysical Research Communications 297, no 1 (septembre 2002) : 24–31. http://dx.doi.org/10.1016/s0006-291x(02)02080-6.

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