HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary table Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Fewer, D. P. Articles by Sivonen, K. Search for Related Content PubMed PubMed Citation Articles by Fewer, D. P. Articles by Sivonen, K. Agricola Articles by Fewer, D. P. Articles by Sivonen, K.

Natural occurrence of microcystin synthetase deletion mutants capable of producing microcystins in strains of the genus Anabaena (Cyanobacteria)

¹ Department of Applied Chemistry and Microbiology, PO Box 56, Viikki Biocenter, Viikinkaari 9, FIN-00014, University of Helsinki, Finland
² Institute of Molecular Biosciences, PO Box 1041, Blindern, University of Oslo, Norway
³ NIVA – Norwegian Institute for Water Research, 0441 Oslo, Norway
⁴ Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Norway

Correspondence
Kaarina Sivonen
kaarina.sivonen{at}helsinki.fi

Microcystins form a large family of small cyclic heptapeptides harbouring extensive modifications in amino acid residue composition and functional group chemistry. These peptide hepatotoxins contain a range of non-proteinogenic amino acids and unusual peptide bonds, and are typically N-methylated. They are synthesized on large enzyme complexes consisting of non-ribosomal peptide synthetases and polyketide synthases in a variety of distantly related cyanobacterial genera. Here we report a 1236 bp in-frame deletion mutation in the mcyA gene of the microcystin biosynthetic pathway in nine strains of the genus Anabaena. The deletion removed almost the entire N-methyltransferase (NMT) domain. Strains of Anabaena carrying the in-frame deletion mutation incorporated mainly dehydroalanine (Dha) into the microcystins they produce while strains with full-length mcyA genes incorporated mainly N-methyldehydroalanine (Mdha). Interestingly, the strains of Anabaena lacking the NMT domain also incorporated elevated amounts of L-Ser, the precursor of Mdha and Dha, into the microcystin they produced relative to strains carrying functional NMT domains. We provide evidence for the in-frame deletion of the NMT domain without the co-conversion of the flanking adenylation domain. Our results demonstrate a further example of the strategies employed by cyanobacteria in the biosynthesis of microcystin variants.

A supplementary table with details of the microcystin variants produced by the 26 strains of Anabaena studied is available with the online version of this paper.

This article has been cited by other articles:

				A. Tooming-Klunderud, B. Mikalsen, T. Kristensen, and K. S. Jakobsen The mosaic structure of the mcyABC operon in Microcystis Microbiology, July 1, 2008; 154(7): 1886 - 1899. [Abstract] [Full Text] [PDF]