Nucleotide sequence and transcriptional analysis of the redD locus of Streptomyces coelicolor A3(2)

Previous genetic evidence suggested that the redD gene product might be involved in the regulation of undecylprodigiosin (Red) biosynthesis in Streptomyces coelicolor. The redD+ gene was subcloned on a 2.2-kilobase-pair restriction fragment from the S. coelicolor redCD region by complementation of S. coelicolor JF1 (redD42). The DNA sequence of the 2.2-kilobase-pair redD-complementing region was determined, and the redD coding sequence was identified by computer analysis and deletion subcloning. Transcription at the redD locus was analyzed by using in vivo promoter probing, high resolution S1 mapping, and in vitro runoff transcription. A face-to-face arrangement of promoters was deduced, in which the proposed redD promoter was opposed by a cluster of four other promoters for another unidentified open reading frame. In time course experiments, redD transcription preceded that at two biosynthetic loci, redE and redBF; transcription at the latter two loci was reduced in redD42 mutants. The putative redD polypeptide lacked any strong sequence similarities to other known proteins.