61(P-33) 淡水産ラン藻が産生するペプチド類の網羅的一斉解析(ポスター発表の部)

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Cyanobacteria (blue-green algae) are known to produce structurally diverse peptides as the secondary metabolites. A serious environmental problem is caused by the production of cyclic hepatotoxin, microcystin, in waterblooms. Microcystin is a hepatotoxic heptapeptide and liver tumor promoter produced by several species of genera Microcystis, Anabaena, Oscillatoria and Nostoc, of which Microcystis is the most deleterious freshwater bloom-forming cyanobacteria. For the regulation of production of microcystins by toxic cyanobacteria, we have investigated their biosynthesis. Microcystin is synthesized non-ribosomally via a mixed polyketide synthase/non-ribosomal peptide synthetase system called microcystin synthetase. Recently Shirai et al. identified whole microcystin synthetase genes in the toxic cyanobacterium. M. aeruginosa K-139, which produces 3-desmethyl and 3,7-didesmethyl microcystin-LR. In our investigations, we have carried out the detection, isolation and structural determination of non-toxic peptides produced together with microcystins by toxic cyanobacteria. As shown in Table 1, the isolated non-toxic peptides were classified into several groups on the basis of their structures. Interestingly, it was confirmed that non-toxic peptides are also non-ribosomally synthesized as well as microcystins. In this study, we tried to correlate the secondary metabolites produced by the hepatotoxic cyanobacteria with the corresponding peptide synthetase genes. An analytical method using ESI-LC/MS on-line photodiode array detection was developed for the exhaustive screening of cyanobacterial peptides in M. aeruginosa K-139 and M. aeruginosa NIES-298 and it was successfully applied to the peptide fractions extracted from these strains. The established method was advantageous over conventional ones using usual HPLC and MALDI-TOFMS, because more structural information could be obtained and it is easier to distinguish microcystins from other peptides using this method. Small amounts of peptides could also be detected by this method. The established method will contribute to the investigation of the relationship between genes encoding peptide synthetase and secondary metabolic peptides.
天然有機化合物討論会の論文
2002-09-01

61(P-33) 淡水産ラン藻が産生するペプチド類の網羅的一斉解析(ポスター発表の部)

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