Biosynthesis of phoslactomycins: cyclohexanecarboxylic acid as the starter unit

Phoslactomycins (PLMs) A–F, produced by actinomycetes are polyketide-type antibiotics derived from a hydroxycyclohexanecarboxylic acid or a cyclohexanecarboxylic acid starter unit. Feeding experiments with [2-13C]shikimic acid indicated that the C-18 carbon of PLMs comes from C-5 of shikimate. Further feeding studies of cis and trans-3-hydroxy[7-13C]cyclohexanecarboxylic acid, [7-13C]- and [2H11]cyclohexanecarboxylic acid have suggested that the starter unit in the PLM biosynthesis is not cis-3-hydroxycyclohexanecarboxylate but cyclohexanecarboxylate and that PLM-B is produced initially, and subsequently converted to other analogs by hydroxylation and acylation.