Over 400 cyanobacterial genera have been described up to the present. Since the Cambridge Rules (https://www.iapt-taxon.org/historic/1935.htm: Rendle 1935), a type species (generitype) must be specified at the time of description for a new genus to be validly described. Even though we have entered a time in which sequencing has become practical and widespread, the basic molecular characterization (e.g., 16S rRNA gene sequence) of most cyanobacterial generitypes is still lacking. About 15 cyanobacterial genera were originally described from Scandinavia. Following a field excursion in which the type or syntype localities for the type species of these genera were visited and sampled, we succeeded in finding three type species from their type or syntype localities: Capsosira brebissonii, Stigonema mamillosum, and Paracapsa siderophila. Epitypes for all three generitypes are herein established. Cells or filaments of C. brebissonii and S. mamillosum were isolated and used for single-cell/filament PCR amplification of the 16S rRNA gene and subsequent cloning and sequencing of the PCR amplicons. This allows a firm establishment of reference sequences of these two genera, to which morphologically similar taxa can now be compared. Stigonema and Capsosira are shown herein to be sister to Aetokthonos hydrillicola, a cyanobacterium known to cause avian vacuolar myelinopathy in birds, including bald eagles.

• Klíčová slova
• Capsosira brebissonii, Paracapsa siderophila, Stigonema mamillosum, 16S rRNA gene, 16S–23S ITS, avian vacuolar myelinopathy, cyanobacteria, generitypes, type locality,
• MeSH
• DNA bakterií genetika   MeSH
• fylogeneze MeSH
• RNA ribozomální 16S genetika   analýza   MeSH
• sekvenční analýza DNA MeSH
• sinice * genetika   klasifikace   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Skandinávie a severské státy MeSH
• Názvy látek
• DNA bakterií MeSH
• RNA ribozomální 16S MeSH

Puwainaphycins (PUWs) and minutissamides (MINs) are structurally analogous cyclic lipopeptides possessing cytotoxic activity. Both types of compound exhibit high structural variability, particularly in the fatty acid (FA) moiety. Although a biosynthetic gene cluster responsible for synthesis of several PUW variants has been proposed in a cyanobacterial strain, the genetic background for MINs remains unexplored. Herein, we report PUW/MIN biosynthetic gene clusters and structural variants from six cyanobacterial strains. Comparison of biosynthetic gene clusters indicates a common origin of the PUW/MIN hybrid nonribosomal peptide synthetase and polyketide synthase. Surprisingly, the biosynthetic gene clusters encode two alternative biosynthetic starter modules, and analysis of structural variants suggests that initiation by each of the starter modules results in lipopeptides of differing lengths and FA substitutions. Among additional modifications of the FA chain, chlorination of minutissamide D was explained by the presence of a putative halogenase gene in the PUW/MIN gene cluster of Anabaena minutissima strain UTEX B 1613. We detected PUW variants bearing an acetyl substitution in Symplocastrum muelleri strain NIVA-CYA 644, consistent with an O-acetyltransferase gene in its biosynthetic gene cluster. The major lipopeptide variants did not exhibit any significant antibacterial activity, and only the PUW F variant was moderately active against yeast, consistent with previously published data suggesting that PUWs/MINs interact preferentially with eukaryotic plasma membranes.IMPORTANCE Herein, we deciphered the most important biosynthetic traits of a prominent group of bioactive lipopeptides. We reveal evidence for initiation of biosynthesis by two alternative starter units hardwired directly in the same gene cluster, eventually resulting in the production of a remarkable range of lipopeptide variants. We identified several unusual tailoring genes potentially involved in modifying the fatty acid chain. Careful characterization of these biosynthetic gene clusters and their diverse products could provide important insight into lipopeptide biosynthesis in prokaryotes. Some of the variants identified exhibit cytotoxic and antifungal properties, and some are associated with a toxigenic biofilm-forming strain. The findings may prove valuable to researchers in the fields of natural product discovery and toxicology.

• Klíčová slova
• biosynthesis, cyanobacteria, fatty acyl-AMP ligase, lipopeptides, nonribosomal peptide synthetase,
• MeSH
• Anabaena genetika   MeSH
• antifungální látky MeSH
• antiinfekční látky MeSH
• bakteriální geny genetika   MeSH
• bakteriální proteiny genetika   MeSH
• cyklické peptidy biosyntéza   chemie   genetika   MeSH
• lipopeptidy biosyntéza   chemie   genetika   farmakologie   MeSH
• multigenová rodina MeSH
• peptidsynthasy genetika   MeSH
• polyketidsynthasy genetika   MeSH
• sinice genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antifungální látky MeSH
• antiinfekční látky MeSH
• bakteriální proteiny MeSH
• cyklické peptidy MeSH
• lipopeptidy MeSH
• non-ribosomal peptide synthase MeSH Prohlížeč
• peptidsynthasy MeSH
• polyketidsynthasy MeSH

A putative operon encoding the biosynthetic pathway for the cytotoxic cyanobacterial lipopeptides puwainphycins was identified in Cylindrospermum alatosporum. Bioinformatics analysis enabled sequential prediction of puwainaphycin biosynthesis; this process is initiated by the activation of a fatty acid residue via fatty acyl-AMP ligase and continued by a multidomain non-ribosomal peptide synthetase/polyketide synthetase. High-resolution mass spectrometry and nuclear magnetic resonance spectroscopy measurements proved the production of puwainaphycin F/G congeners differing in FA chain length formed by either 3-amino-2-hydroxy-4-methyl dodecanoic acid (4-methyl-Ahdoa) or 3-amino-2-hydroxy-4-methyl tetradecanoic acid (4-methyl-Ahtea). Because only one puwainaphycin operon was recovered in the genome, we suggest that the fatty acyl-AMP ligase and one of the amino acid adenylation domains (Asn/Gln) show extended substrate specificity. Our results provide the first insight into the biosynthesis of frequently occurring β-amino fatty acid lipopeptides in cyanobacteria, which may facilitate analytical assessment and development of monitoring tools for cytotoxic cyanobacterial lipopeptides.

• MeSH
• anotace sekvence MeSH
• bakteriální geny MeSH
• bakteriální proteiny genetika   fyziologie   MeSH
• biosyntetické dráhy MeSH
• ligasy genetika   fyziologie   MeSH
• lipopeptidy biosyntéza   MeSH
• molekulární sekvence - údaje MeSH
• multigenová rodina MeSH
• polyketidsynthasy genetika   fyziologie   MeSH
• sinice enzymologie   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• ligasy MeSH
• lipopeptidy MeSH
• polyketidsynthasy MeSH
• puwainaphycin F MeSH Prohlížeč
• puwainaphycin G MeSH Prohlížeč