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

Abstract

A region of the Streptomyces coelicolor A3(2) chromosome was identified and cloned by using as a probe the lipase gene from Streptomyces exfoliatus M11. The cloned region consisted of 6286 bp, and carried a complete lipase gene, lipA, as well as a gene encoding a transcriptional activator (lipR). The S. coelicolor A3(2) lipA gene encodes a functional extracellular lipase 82% identical to the S. exfoliatus M11 lipase; the partially purified S. coelicolor 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 promoters have well-conserved -10 and -35 regions, as well as additional conserved sequences upstream of the -35 region, which could function as targets for transcriptional activation by the cognate LipR regulators. The Streptomyces LipR activators are related to other bacterial regulators of a similar size, constituting a previously unidentified family of proteins that includes MalT, AcoK, AlkS, AfsR, five mycobacterial proteins of unknown function and some Streptomyces regulators in antibiotic synthesis clusters. A lipase-deficient strain of S. coelicolor was constructed and found to be slightly affected in production of the polyketide antibiotic actinorhodin.