Recurrent adenylation domain replacement in the microcystin synthetase gene cluster

Fewer, David P.; Rouhiainen, Leo; Jokela, Jouni; Wahlsten, Matti; Laakso, Kati; Wang, Hao; Sivonen, Kaarina

doi:10.1186/1471-2148-7-183

Cited by 108 publications

(112 citation statements)

References 33 publications

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“…Deletion mutants of the N-methyltransferase domain of mcyA in microcystin producing Anabaena strains were still able to synthesize microcystin . Independent recombination of adenylation domains without their associated condensation domains resulted in the generation of functional new peptide synthetases (Fewer et al, 2007), thereby confirming that gene reorganization is a common means of diversification of non-ribosomal peptide synthesis in the cyanobacteria. Nostoc strains are known to associate symbiotically with a wide range of hosts, such as diatoms, bryophytes (lichens and hornworts), pteridophytes (Azolla), gymnosperms (cycads) and angiosperms (Gunnera) (Rai et al, 2000;Bergman et al, 2007).…”

Section: Introductionmentioning

confidence: 76%

Nodularin, a cyanobacterial toxin, is synthesized in planta by symbiotic Nostoc sp.

et al. 2012

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The nitrogen-fixing bacterium, Nostoc, is a commonly occurring cyanobacterium often found in symbiotic associations. We investigated the potential of cycad cyanobacterial endosymbionts to synthesize microcystin/nodularin. Endosymbiont DNA was screened for the aminotransferase domain of the toxin biosynthesis gene clusters. Five endosymbionts carrying the gene were screened for bioactivity. Extracts of two isolates inhibited protein phosphatase 2A and were further analyzed using electrospray ionization mass spectrometry (ESI-MS)/MS. Nostoc sp. ‘Macrozamia riedlei 65.1’ and Nostoc sp. ‘Macrozamia serpentina 73.1’ both contained nodularin. High performance liquid chromatography (HPLC) HESI-MS/MS analysis confirmed the presence of nodularin at 9.55±2.4 ng μg−1 chlorophyll a in Nostoc sp. ‘Macrozamia riedlei 65.1’ and 12.5±8.4 ng μg−1 Chl a in Nostoc sp. ‘Macrozamia serpentina 73.1’ extracts. Further scans indicated the presence of the rare isoform [L-Har2] nodularin, which contains l-homoarginine instead of l-arginine. Nodularin was also present at 1.34±0.74 ng ml−1 (approximately 3 pmol per g plant ww) in the methanol root extracts of M. riedlei MZ65, while the presence of [L-Har2] nodularin in the roots of M. serpentina MZ73 was suggested by HPLC HESI-MS/MS analysis. The ndaA-B and ndaF genomic regions were sequenced to confirm the presence of the hybrid polyketide/non-ribosomal gene cluster. A seven amino-acid insertion into the NdaA-C1 domain of N. spumigena NSOR10 protein was observed in all endosymbiont-derived sequences, suggesting the transfer of the nda cluster from N. spumigena to terrestrial Nostoc species. This study demonstrates the synthesis of nodularin and [L-Har2] nodularin in a non-Nodularia species and the production of cyanobacterial hepatotoxin by a symbiont in planta.

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Section: Introductionmentioning

confidence: 76%

Nodularin, a cyanobacterial toxin, is synthesized in planta by symbiotic Nostoc sp.

et al. 2012

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“…In this study an effort was made to elucidate the genetic basis responsible for the structural variation of APs among isolates of the genus Planktothrix. While this approach has been applied previously (10,24,25,30,45), until now none of the reported genetic variants has been probed biochemically. Therefore, the biochemical consequences of genetic variation within A domains in toxin-producing cyanobacteria have remained elusive.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, one can postulate that the first A domain of McyB (the McyB A 1 domain), which is responsible for the activation of amino acids in position 2 of the MC molecule, is able to activate Arg and Leu (4). The polymorphism within the mcyB A 1 domain, as observed for the genera Microcystis, Planktothrix, and Anabaena, has been investigated in detail (10,26,30,45). Within each genus, the genetic variation within the mcyB A 1 domain could be correlated with a specific structural variation in position 2 of the MC molecules found in the genus.…”

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confidence: 99%

Genetic Variation of Adenylation Domains of the Anabaenopeptin Synthesis Operon and Evolution of Substrate Promiscuity

et al. 2011

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“…Amplification of the cyanobacterial mcyE gene from lichen samples was performed with the primers mcyEF dgn and mcyER dgn (40). Initial screening was performed in a 30-μL volume containing 1 μL genomic DNA, 200 μM deoxynucleoside triphosphate (Finnzymes), 0.5 μM each primer, 0.5 U of Phusion high-fidelity DNA polymerase (Finnzymes), and 3% (vol/vol) DMSO (Finnzymes).…”

Section: Methodsmentioning

confidence: 99%

Cyanobacteria produce a high variety of hepatotoxic peptides in lichen symbiosis

Kaasalainen¹,

Fewer

Jokela

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Lichens are symbiotic associations between fungi and photosynthetic algae or cyanobacteria. Microcystins are potent toxins that are responsible for the poisoning of both humans and animals. These toxins are mainly associated with aquatic cyanobacterial blooms, but here we show that the cyanobacterial symbionts of terrestrial lichens from all over the world commonly produce microcystins. We screened 803 lichen specimens from five different continents for cyanobacterial toxins by amplifying a part of the gene cluster encoding the enzyme complex responsible for microcystin production and detecting toxins directly from lichen thalli. We found either the biosynthetic genes for making microcystins or the toxin itself in 12% of all analyzed lichen specimens. A plethora of different microcystins was found with over 50 chemical variants, and many of the variants detected have only rarely been reported from free-living cyanobacteria. In addition, high amounts of nodularin, up to 60 μg g −1 , were detected from some lichen thalli. This microcystin analog and potent hepatotoxin has previously been known only from the aquatic bloom-forming genus Nodularia. Our results demonstrate that the production of cyanobacterial hepatotoxins in lichen symbiosis is a global phenomenon and occurs in many different lichen lineages. The very high genetic diversity of the mcyE gene and the chemical diversity of microcystins suggest that lichen symbioses may have been an important environment for diversification of these cyanobacteria.Nostoc | Peltigera | cyanolichen | secondary metabolites | chemical defence

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Recurrent adenylation domain replacement in the microcystin synthetase gene cluster

Cited by 108 publications

References 33 publications

Nodularin, a cyanobacterial toxin, is synthesized in planta by symbiotic Nostoc sp.

Nodularin, a cyanobacterial toxin, is synthesized in planta by symbiotic Nostoc sp.

Genetic Variation of Adenylation Domains of the Anabaenopeptin Synthesis Operon and Evolution of Substrate Promiscuity

Cyanobacteria produce a high variety of hepatotoxic peptides in lichen symbiosis

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