1887

Abstract

It was demonstrated previously that the operon consisting of the non-ribosomal peptide synthetase (NRPS) gene coupled with the polyketide synthase (PKS) gene involved in cyclic heptapeptide microcystin synthesis includes two different D-amino acid synthetase genes, an epimerization domain at the 3′ end of module 2, and the racemase gene . To determine the role of in microcystin synthesis, gene-disruption and complementation analyses were carried out. Insertional mutagenesis in the gene, generated by homologous recombination, abolished only microcystin synthesis, but did not influence cell growth. Furthermore, McyF supported D-Glu-independent growth of a strain of defective in D-Glu synthesis. It is concluded that is the glutamic acid racemase gene involved in the synthesis of D-Glu residues in the microcystin molecule. This is the first report of the racemase in prokaryotic NRPS.

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2001-05-01
2024-12-14
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