The effect of methylation inhibitors on citreamicin biosynthesis in Micromonospora citrea

Neocitreamicins I and II, novel antibiotics with activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci

Two novel antibiotics, neocitreamicins I and II, were isolated from a fermentation broth of a Nocardia strain. This producing strain was obtained using an in situ diffusion chamber that facilitates the cultivation of soil microorganisms. The structures of neocitreamicins I and II were elucidated using UV, MS, and NMR data, and found to be related to the polycyclic xanthone antibiotics of the citreamicin class. The neocitreamicins showed in vitro activity against Gram-positive bacteria including strains of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis.

O- and N-methylation in the biosynthesis of staurosporine

The feeding of (13)C- and (2)H-enriched methionine to Streptomyces staurosporeus established that the methyl carbon and proton source of both the 3'-O- and 4'-N-methyl groups of staurosporine (1) was methionine and that all three methyl protons from methionine were retained on 1. In the presence of the methyltransferase inhibitor, sinefungin, the biosynthesis of staurosporine was blocked at the last step, O-methylation. An intermediate, 3'-demethoxy-3'-hydroxystaurosporine (2), was efficiently accumulated in the medium. Other general methyltransferase inhibitors failed to produce any other staurosporine intermediates or analogues.

A new cytosine glycoside from Streptomyces griseochromogenes produced by the use in vivo of enzyme inhibitors

The identification of new cytosine glycosides and intermediates in the biosynthetic pathway of the antifungal antibiotic blasticidin S (1) was investigated using in vivo enzyme inhibition. Fermentations of Streptomyces griseochromogenes, the organism that produces 1, supplemented with the arginine analogue argininic acid or the argininosuccinate synthase inhibitor 2-methylaspartic acid were found to produce a new metabolite (7).