In vitro analysis of the butyrolactone autoregulator receptor protein (FarA) of Streptomyces lavendulae FRI-5 reveals that FarA acts as a DNA-bindingtranscriptional regulator that controls its own synthesis

FarA of Streptomyces lavendulae FRI-5 is a specific receptor protein for IM -2, a butyrolactone autoregulator that controls the production of a blue pi gment and the nucleoside antibiotics showdomycin and minimycin, Gel shift a ssays demonstrated that FarA binds to the farA upstream region and that thi s binding is abolished in the presence of IM-2. The FarA binding sequence w as localized by DNase I footprinting to a 28-bp sequence located approximat ely 70 bp upstream of the farA translational start site. High-resolution S1 nuclease mapping of farA transcripts revealed a putative transcription sta rt site, located at an A residue positioned 64 bp upstream from the favA tr anslation start codon and 4 bp downstream from an Escherichia coli sigma(70 )-like -10 recognition region. The FarA-binding sequence overlaps this -10 region and contains the farA transcription initiation site, suggesting that FarA acts as a repressor that, in the absence of IM-2, represses transcrip tion of farA.