The mosaic structure of the mcyABC operon in Microcystis

University of Oslo, Department of Molecular Biosciences, 0316 Oslo, Norway.
Microbiology (Impact Factor: 2.56). 08/2008; 154(Pt 7):1886-99. DOI: 10.1099/mic.0.2007/015875-0
Source: PubMed


An extensive study of the mcyABC genes and regions flanking the mcy gene cluster was performed in naturally occurring Microcystis strains. Lack of methylation in strains producing only desmethyl(7)-microcystin was found to be associated with point mutations in substrate-binding sequence motifs of the N-methyltransferase (NMT) domain in McyA. Multiple recombination events giving rise to 'phylogenetic mosaics' were detected within the NMT-domain-encoding mcyA sequences and the adenylation (A) domain sequences of mcyB and mcyC. Recombination leading to exchanges between the mcyB and mcyC regions encoding A domains in modules McyB1 and McyC was also detected. A previously reported replacement of the A domain in McyB1 was found to involve the region between the conserved motifs A3 and A8/A9. In all microcystin-producing strains the mcy gene cluster was flanked by the genes uma1 and dnaN. Clear indications of recombination, an insertion element and footprints of IS elements were found in the dnaN-mcyJ intergenic region. Among the non-microcystin producers, uma1 and dnaN were linked in some, but not all strains. Most non-producing strains lacked all mcy genes, while one strain possessed a partially deleted mcy operon. Our results show that frequent horizontal gene transfer events in addition to point mutations and insertions/deletions contribute to variation in the mcy gene cluster.

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    • "In other Planktothrix-dominated European lakes, the presence of at least one of the five demethylated MCs was also recorded (Barco et al. 2004; Welker et al. 2004a; Kurmayer et al. 2005; Briand et al. 2005; Welker and Erhard 2007; Bauman and Jüttner 2008; Tooming-Klunderud et al. 2008; Rohrlack et al. 2009; Rounge et al. 2009). Four of the microcystins (m/z 981, 1,024, 1,031, 1,045) were identified in field samples and in the P. agardhii isolates from Viry-Chãtillon’s lake in France (Yépremian et al. 2007). "
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    ABSTRACT: Planktothtrix agardhii (Oscillatoriales) is a filamentous cyanobacterium, which frequently forms blooms in shallow, polymictic and eutrophicated waters. This species is also a rich source of unique linear and cyclic peptides. In the current study, the profile of the peptides in samples from the P. agardhii-dominated Siemianówka Dam Reservoir (SDR) (northeast Poland) was analyzed for four subsequent years (2009–2012). The LC–MS/MS analyses revealed the presence of 33 peptides. Twelve of the most abundant ones, including five microcystins, five anabaenopeptins, one aeruginosin and one planktocyclin, were present in all field samples collected during the study. The detection of different peptides in two P. agardhii isolates indicated that the SDR population was composed of several chemotypes, characterized by different peptide patterns. The total concentration of microcystins (MCs) positively correlated with the biomass of P. agardhii. Between subsequent years, the changes in the ratio of the total MCs concentration to the biomass of P. agardhii were noticed, but they were less than threefold. This is the first study on the production of different classes of non-ribosomal peptides by freshwater cyanobacteria in Poland. Electronic supplementary material The online version of this article (doi:10.1007/s00203-014-1008-9) contains supplementary material, which is available to authorized users.
    Full-text · Article · Jun 2014 · Archives of Microbiology
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    • "Positive selection acting on the adenylation domains of McyB1 and McyC was reported as the possible cause of the large number of microcystin variants produced by cyanobacteria [24]. Deletion of the entire N-methyltransferase domain of mcyA in Anabaena or point mutations in this gene in Microcystis were associated with the absence of N-methylation in the microcystins produced by these strains [23,26]. Furthermore, recombination in the same region (mcyA1) was related to the synthesis of microcystins containing 2-amino-2-butenoic acid (Dhb) in some strains of the genus Planktothrix[25]. "
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    Full-text · Article · Apr 2013 · BMC Evolutionary Biology
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    • "Intriguingly, this region almost precisely corresponds to the amino acid recognition pocket previously identified in structural studies (Conti et al., 1997). These features provide direct insights into the evolution of NRPS systems, suggesting a scenario in which new NRPS functionality can already arise by recombinatorial exchange of only short DNA stretches covering the specificity region, in addition to the previously observed exchanges of entire modules (Rounge et al., 2008), A domains (Fewer et al., 2007; Ishida et al., 2009), or multiple regions (Tooming-Klunderud et al., 2008). "
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    Full-text · Article · Mar 2011 · Chemistry & biology
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