Cypemycin, isolated from the bacterium Streptomyces sp. OH-4156, is a peptide antibiotic, member of the linaridins, a class of posttranslationally modified ribosomally synthesized peptides. The enzyme decarboxylates and reduces the C-terminal L-cysteine residue, producing a reactive ethenethiol group that reacts with a dethiolated cysteine upstream to form an aminovinyl-methyl-cysteine loop that is important for the antibiotic activity of the mature peptide.
Claesen, J. and Bibb, M. Genome mining and genetic analysis of cypemycin biosynthesis reveal an unusual class of posttranslationally modified peptides. Proc. Natl. Acad. Sci. USA107 (2010) 16297–16302. [PMID: 20805503]