Breaking Away

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Science  13 Aug 2004:
Vol. 305, Issue 5686, pp. 919
DOI: 10.1126/science.305.5686.919a

The streptomycetes group of soil bacteria is familiar as the source of medically important antibiotics, such as streptomycin and other small macrocyclic molecules collectively known as polyketides for their mode of biosynthesis. During the life cycle of S. coelicolor, multinuclear aerial structures called hyphae extend from the substratum into the air; subsequently, each nucleus is walled off to form a spore. In order to push the hyphae through the air/water interface, the bacterium secretes SapB, a spore-associated peptide that acts as a surfactant and reduces surface tension.

Kodani et al. connect bacterial morphogenesis to antibiotic biosynthesis by showing that SapB is encoded by the ramS gene and that its structure is akin to those of antimicrobial oligopeptides known as lantibiotics, named for the posttranslational processing that generates intramolecular thioether (lanthionine) crosslinks. These posttranslational modifications are effected in part by the protein encoded by another gene of the ram (rapid aerial mycelium) operon, ramC, which exhibits sequence similarity to known lantibiotic cyclases. — GJC

Proc. Natl. Acad. Sci. U.S.A. 101, 11448 (2004).

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