Academic literature on the topic 'Cyanopeptoline'

ABSTRACT The major cyclic peptide cyanopeptolin 1138, produced by Planktothrix strain NIVA CYA 116, was characterized and shown to be structurally very close to the earlier-characterized oscillapeptin E. A cyanopeptolin gene cluster likely to encode the corresponding peptide synthetase was sequenced from the same strain. The 30-kb oci gene cluster contains two novel domains previously not detected in nonribosomal peptide synthetase gene clusters (a putative glyceric acid-activating domain and a sulfotransferase domain), in addition to seven nonribosomal peptide synthetase modules. Unlike in two previously described cyanopeptolin gene clusters from Anabaena and Microcystis, a halogenase gene is not present. The three cyanopeptolin gene clusters show similar gene and domain arrangements, while the binding pocket signatures deduced from the adenylation domain sequences and the additional tailoring domains vary. This suggests loss and gain of tailoring domains within each genus, after the diversification of the three clades, as major events leading to the present diversity. The ABC transporter genes associated with the cyanopeptolin gene clusters form a monophyletic clade and accordingly are likely to have evolved as part of the functional unit. Phylogenetic analyses of adenylation and condensation domains, including domains from cyanopeptolins and microcystins, show a closer similarity between the Planktothrix and Microcystis cyanopeptolin domains than between these and the Anabaena domain. No clear evidence of recombination between cyanopeptolins and microcystins could be detected. There were no strong indications of horizontal gene transfer of cyanopeptolin gene sequences across the three genera, supporting independent evolution within each genus.

ABSTRACT Besides the most prominent peptide toxin, microcystin, the cyanobacteria Microcystis spp. have been shown to produce a large variety of other bioactive oligopeptides. We investigated for the first time the oligopeptide diversity within a naturalMicrocystis population by analyzing single colonies directly with matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). The results demonstrate a high diversity of known cyanobacterial peptides such as microcystins, anabaenopeptins, microginins, aeruginosins, and cyanopeptolins, but also many unknown substances in the Microcystis colonies. Oligopeptide patterns were mostly related to specificMicrocystis taxa. Microcystis aeruginosa(Kütz.) Kütz. colonies contained mainly microcystins, occasionally accompanied by aeruginosins. In contrast, microcystins were not detected in Microcystis ichthyoblabeKütz.; instead, colonies of this species contained anabaenopeptins and/or microginins or unknown peptides. Within a third group, Microcystis wesenbergii (Kom.) Kom. in Kondr., chiefly a cyanopeptolin and an unknown peptide were found. Similar patterns, however, were also found in colonies which could not be identified to species level. The significance of oligopeptides as a chemotaxonomic tool within the genus Microcystis is discussed. It could be demonstrated that the typing of single colonies by MALDI-TOF MS may be a valuable tool for ecological studies of the genus Microcystis as well as in early warning of toxic cyanobacterial blooms.

Ahp-cyclodepsipeptides (also known as Ahp-containing cyclodepsipeptides, cyanopeptolins, micropeptins, microginines, and lyngbyastatins, and by many other names) are a natural product family with potent serine protease inhibitory properties.

Les cyanobactéries sont des organismes procaryotes photosynthétiques capables de produire de nombreux métabolites secondaires. Cette thèse s’intéresse à la caractérisation moléculaire de cyanobactéries productrices de neurotoxines (anatoxine-a et homoanatoxine-a) ainsi qu’à la mise en évidence d’un gène codant pour une activité halogénase dans les clusters de gènes de biosynthèse des métabolites : cyanopeptoline et aéruginosine. De nombreux cas d'intoxications neurotoxiques d'animaux sauvages et domestiques sont régulièrement reportés en France. Nous avons mis en évidence sur deux sites pour lesquels des épisodes mortels ont été rapportés la présence de neurotoxines de cyanobactéries. Les cyanobactéries productrices d’anatoxine-a ont été isolées et déposées dans la collection de cyanobactéries de l’Institut Pasteur PCC. La caractérisation phénotypique et génétique des souches axéniques obtenues montre qu’il s’agit de souches du genre Oscillatoria. Sur la base des séquences codant pour les ARNr16S et ITS (Internal Transcribed Spacer) les relations phylogénétiques des nouvelles souches neurotoxiques au sein du genre Oscillatoria ont été étudiées. Une étude du contenu métabolique en cyanopeptoline et aéruginosine et de la présence des leur clusters de gènes de biosynthèse a été entreprise chez une trentaine de souches de Microcystis. Elle a permis de mettre en évidence la présence d’halométabolites et d’identifier les gènes portant l’activité halogénase au sein des clusters aer et mcn. L’histoire évolutive des clusters aer et mcn au sein du genre Microcystis a été reconstituée par analyse des séquences ITS. Le gène halogénase semble avoir été acquis par la cyanobactérie probablement d'une protéobactérie ancestrale par transfert horinzontal
This work of PhD is cantered around three secondary metabolites produced by cyanobacteria (cyanopeptolin, aeruginosin and anatoxin-a). The first part of this work reports the results about isolating and purifing neurotoxic cyanobacteria from natural samples. Repeated dog deaths occurred in the last years in southern France. Signs of intoxication indicated acute poisoning due to a neurotoxin. Samples were collected at the border of tarn river in summers 2005 and 2006 from six different sites along 30 km. The cyanobacterial neurotoxines anatoxin-a and homoanatoxin-a were detected in extracts of most samples examined by gas chromatography-mass spectrometry. Fifteen filamentous cyanobacteria of the order Oscillatoriales were isolated and displayed four distinct phenotypes. Three of the phenotypes are assignable to the genera Oscillatoria/Phormidium, the fourth to the genus Geitlerinema. The genetic relatedness of the new isolates was evaluated by comparison of the ITS sequences with those of six oscillatorian strains from the PCC collection. Our findings prove that neurotoxic oscillatorian cyanobacteria exist in the Tarn river and thus were most likely implicated in the reported dog poisonings. Furthermore, they re-emphasise the importance of monitoring benthic cyanobacteria in aquatic environments. The second part of this work presents the evolution of the halogenase genes of the strains Microcystis sp. Producing chloreted cyanopeptolin and aeruginosin. Twenty-eight axenic strains of Microcystis aeruginosa from the PCC and NIES culture collections were screened by MALDI-TOF mass spectrometry and their genome analysed by degenerated oligonucleotides. Two putative halogenase genes present in cyanopeptoline and aeruginosin synthetase clusters were identified. Their nucleotide and deduced amino acid sequences were analysed in detail. A phylogenetic study was conducted on thirty halogenase and putative halogenase genes from different microorganisms

Cyanobacteria are one of the oldest forms of photosynthetic life and may have contributed significantly to the evolution of oxygen into the then anoxic environment. Cyanobacteria are also one of the best sources of natural secondary metabolites (cyanopeptides) some of which have harmful effects on the ecosystem, while others may be beneficial. It is known that these secondary metabolites are continuously produced during growth, however, it is not known whether the producing cyanobacteria actually benefit from these metabolites. The overarching aim of this study was to answer the question ‘Why do cyanobacteria produce secondary metabolites?’. With this aim in mind, preliminary work focused on understanding the growth and secondary metabolite production characteristics of Microcystis aeruginosa PCC7806. The technique of labelling secondary metabolites with 15N was successfully employed in differentiation and quantification of ex-novo and de-novo metabolites. The effect of exogenous cyanopeptides such as microcystins, aerucyclamides, anabaenopeptins, aeruginosamide, cyanopeptolin and aeruginosin on M. aeruginosa PCC7806 was evaluated using a rapid bioassay approach along with an automated cell enumeration technique. The results indicate that at least some cyanopeptides (microcystins-LR, microcystin-LF, aeruginosamide, anabaenopeptin B and aerucyclamide A) induce significant changes to cell division and metabolite production rate. In an ecological scenario, the release of such secondary metabolites by lysing cells (such as when blooms collapse), may be perceived as an alarm signal by surrounding live cells, which may in turn slow cell division and prepare for re-invasion. This may be a strategy for species survival and dominance. While the results from this study do not confirm a role for cyanopeptides, it is thought that the results are clearly indicative of the role played by cyanopeptides for the producing organism. In order to confirm a role, it is recommended that monitoring ribosomally synthesised metabolites (e.g. aerucyclamides) along with chlorophyll-a gene expression, with sophisticated techniques such as qPCR are used.

A filosfera da Mata Atlântica é um importante nicho de colonização por micro-organismos, cuja comunidade ainda é pouco conhecida. Algumas bactérias associadas à superfície das folhas possuem habilidade de fixar nitrogênio, mineralizar substratos orgânicos e também suprir as árvores com dióxido de carbono e fatores de crescimento. Este trabalho teve como objetivo gerar informações sobre a comunidade cianobacteriana que coloniza a filosfera de algumas plantas da Mata Atlântica e investigar a comunidade diazotrófica presente nesse habitat. Um total de 40 linhagens de cianobactérias da filosfera de Merostachys neesii (bambu), Euterpe edulis (palmeira Juçara), Guapira opposita e Garcinia gardneriana foram isoladas e cultivadas. Os isolados foram caracterizados por análises morfológicas e filogenia do gene 16S RNAr. Essa abordagem permitiu a identificação de uma linhagem do gênero Nostoc, sete Desmonostoc, seis Leptolyngbya, uma Oculatella, cinco Brasilonema, uma Pleurocapsa e duas Chroococcidiopsis. Dezessete linhagens (uma Microchaetaceae, dez Nostocaceae e seis Pseudanabaenaceae) não puderam ser identificadas ao nível de gênero. Vinte e seis linhagens (24 pertencentes às ordens Nostocales e duas à Pseudanabaenales) foram caracterizadas como diazotróficas pela amplificação, sequenciamento e filogenia do gene nifH. Além disso, caracterizou-se o perfil de fixação biológica de nitrogênio da linhagem Desmonostoc sp. CENA362. Com relação ao potencial biotecnológico dessas linhagens, treze isolados foram identificados como potenciais produtores de ácido indol acético (IAA) de acordo com o teste Salkowski. Diversas linhagens apresentaram genes associados à via biossintética do inibidor de protease microviridina, sendo que três delas codificam para novas variantes. Além disso, dez linhagens foram identificadas como potenciais produtoras aeruginosina, três de cianopeptolina e três de microcistina. A comunidade bacteriana diazotrófica avaliada por pirosequenciamento do gene nifH apresentou um perfil de variação espécie-específica para Proteobacteria e uma correlação positiva entre a riqueza e a fixação biológica de nitrogênio. Neste estudo, cianobactérias que habitam a filosfera da Mata Atlântica foram isoladas estão sendo mantidas em condições de cultivo. Novos táxons foram descobertos e vários gêneros conhecidos foram descritos pela primeira vez neste hábitat, o que contribuiu para o aprimoramento da sistemática de Cyanobacteria. As linhagens em cultivo e as informações geradas sobre os seus compostos metabólitos representam uma valiosa fonte para estudos posteriores. Além disso, informações sobre a comunidade bacteriana diazotrófica da filosfera pode auxiliar no entendimento da dinâmica do nitrogênio, elemento limitante e pouco disponível na Mata Atlântica
The phyllosphere of the Atlantic Forest is an important niche for colonization by microorganisms, whose community is still little known. Some bacteria associated with leaf surfaces may possess the ability to fix nitrogen, mineralize the organic substrates and also supply the trees with carbon dioxide and growth factors. Therefore, this study aimed to generate information about cyanobacterial community that colonize the phyllosphere of some plants of the Atlantic Forest and investigated the diazotrophic community in this habitat. A total of 40 strains of Cyanobacteria from the phyllosphere of Merostachys neesii (bamboo), Euterpe edulis (Juçara palm), Garcinia gardneriana and Guapira opposita was isolated and cultivated. The isolates were characterized by morphological analyses and phylogeny of the 16S rRNA gene. This approach allowed the identification of one strain of the genus Nostoc, seven Desmonostoc, six Leptolyngbya, one Oculatella, five Brasilonema, one Pleurocapsa and two Chroococcidiopsis. Seventeen strains (one Microchaetaceae, ten Nostocaceae and six Pseudanabaenaceae) could not be identified at the genus level. Twenty-six strains (24 belonging to Nostocales and two belonging to Pseudanabaenales) were characterized as diazotrophic by amplification, sequencing and phylogeny of nifH gene. Also, it was characterized the profile of biological nitrogen fixation for the strain Desmonostoc sp. CENA362. Regarding the biotechnological potential of these strains, thirteen strains were identified as potential producers of indole acetic acid (IAA) according to Salkowski test. Several strains presented genes involved in the biosynthetic pathway of the protease inhibitor microviridin, three of them encoding putative novel variants. Moreover, ten strains were identified as potential producers of aeruginosin, three of cyanopeptolin and three of microcystin. The diazotrophic bacterial community evaluated by pyrosequencing of the nifH gene showed a profile of variation plant species-specific for Proteobacteria, and a positive correlation between richness and biological nitrogen fixation. In this study, cyanobacteria that inhabiting Brazilian Atlantic Forest phyllosphere were isolated and are been maintained in culture conditions. New taxa were discovered and several known genera were described for the first time in this habitat, which contributed to improvement of the cyanobacterial systematic. The culturable strains and the information generated about their metabolites compounds represent a valuable source for further studies. In addition, information about the diazotrophic bacterial community inhabiting the phyllosphere may help in understanding the dynamics of nitrogen, a limiting and low available element in Atlantic Forest