The Streptomyces coelicolor A3(2) lipAR operon encodes an extracellular lipase and a new type of transcriptional regulator

A region of the Streptomyces coelicolor A3(2) chromosome was identified and cloned by using as a probe the lipase gene from Streptomyces exfoliatus M1 1. The cloned region consisted of 6286 bp, and carried a complete lipase ge ne, lipA, as well as a gene encoding a transcriptional activator (lipR). Th e S. coelicolor A3(2) lipA gene encodes a functional extracellular lipase 8 2 % identical to the S. exfoliatus M11 lipase; the partially purified S. co elicolor enzyme showed a preference for substrates of short to medium chain length. Transcription of lipA was completely dependent on the presence of lipR, and occurred from a single promoter similar to the lipA promoters of S. exfoliatus M11 and Streptomyces albus G. These three Streptomyces lipA p romoters have well-conserved -10 and -35 regions, as well as additional con served sequences upstream of the -35 region, which could function as target s for transcriptional activation by the cognate LipR regulators. The Strept omyces LipR activators are related to other bacterial regulators of a simil ar size, constituting a previously unidentified family of proteins that inc ludes MalT, AcoK, AlkS, AfsR, five mycobacterial proteins of unknown functi on and some Streptomyces regulators in antibiotic synthesis clusters. A lip ase-deficient strain of S. coelicolor was constructed and found to be sligh tly affected in production of the polyketide antibiotic actinorhodin.