Gene Organization in a 12-Kilobase Region Covering afsA Encoding an A-Factor Biosynthetic Enzyme.

Abstract

The nucleotide sequence of a 12-kilobase region covering afsA encoding a key enzyme for A- factor biosynthesis in Streptomyces griseus was determined and open reading frames were deduced by means of G+C plot analysis. Although this region about 150-kb from one end of the linear chromosome is known to be readily deleted, open reading frames crowd the region in a total of eleven, including afsA and sgaA involved in healthy growth on medium of high osmolality. These also include a pair of a sensor histidine kinase and a regulator which comprises a typical prokaryotic two-component regulatory system, proteins similar to O-methyltransferase, LysR-type regulator, 3-ketoacyl-acyl carrier protein reductase, and NADP-dependent alcohol dehydrogenase. In contrast to afsA-like genes in other Streptomyces strains, such as barX locating closely to the gene for the virginiae butanolide receptor in Streptomyces virginiae and farX locating closely to the IM-2-receptor gene in a Streptomyces sp., no open reading frames in this region in S. griseus show homology with the A-factor receptor protein, which suggests that the gene organization of receptor genes for γ-butyrolactone autoregulators differs from strain to strain.