Streptomyces rochei 7434AN4 predominantly produces lankacidin and lankamycin under normal culture conditions, suggesting that other biosynthetic gene clusters for secondary metabolites are silent. To exploit silent metabolites of strain 7434AN4, we constructed mutant KA57, a multiple disruptant of the transcriptional repressor gene srrB together with the biosynthesis genes for both antibiotics. Mutant KA57 accumulated a compound (KA57-A) with a strong UV absorption at 235 nm, which was not detected in the parent strain or other mutants. Various spectroscopic analyses revealed that KA57-A is an azoxyalkene compound of a molecular formula of C10H20N2O3 with the R configuration at C-2. Biosynthesis of KA57-A was also studied by feeding with labeled acetates, amino acids, and 1-hexylamine. The hexenyl moiety (C1’-C6’) was derived from fatty acid, while the 3-amino-butan-1,2-diol moiety (C1-C4) was derived from C-2 of acetate (C1) and serine (C2-C4). Incorporation of [1,1-2H2]1-hexylamine indicated that C1’-C2’ dehydrogenation occurs at the final step of biosynthesis.

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This work was supported by a Grants‐in‐Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT), and a Noda Institute for Scientific Research Grant.

Supporting information for this articleis available on the WWW under http://dx.doi.org/10.1002/cbic.201500393.