AfsR2: a previously undetected gene encoding a 63-- amino--acid protein that stimulates antibiotic production in Strptomyces lividans.

Earlier work has shown that the afsfR genetic locus promotes formation of the pigmented antibiotics actinorhadin and undecylprodiglosin in Streptomyces lividans and its close relative, Streptomyces coelicolor. A protein designated as AfsR has been implicated in this activity. We report here the existence of a previously unknown gene, afsR2, which is separate from and adjacent to the AfsR-encoding sequence and which, when present at high copy number, (i) stimulates transcription of biosynthetic and regulatory genes in the actinorhodin gene cluster (act), and (ii) stimulates the synthesis of undecyiprodigiosin. We show that the effects of afsR2 on actinorhodin synthesis are mediated through transcription of the acni-0RF4 locus, which encodes a transcriptional activator of other genes in the act cluster. Analysis of the cloned afsR2 gene indicates that its activity is the result of the 63-amino-acid protein it specifies. [ABSTRACT FROM AUTHOR]