Structure and function of the arginine repressor-operator complex from Bacillus subtilis.

In many bacteria, the concentration of L-arginine is controlled by a transcriptional regulator, the arginine repressor. In Bacillus subtilis this transcription factor is called AhrC and has roles in both the repression and activation of the genes involved in arginine metabolism. It interacts with 18 bp ARG boxes in the promoters of arginine biosynthetic and catabolic operons.

Structure of the C-terminal effector-binding domain of AhrC bound to its corepressor L-arginine.

The arginine repressor/activator protein (AhrC) from Bacillus subtilis belongs to a large family of multifunctional transcription factors that are involved in the regulation of bacterial arginine metabolism. AhrC interacts with operator sites in the promoters of arginine biosynthetic and catabolic operons, acting as a transcriptional repressor at biosynthetic sites and an activator of transcription at catabolic sites. AhrC is a hexamer of identical subunits, each having two domains.

A high-resolution structure of the DNA-binding domain of AhrC, the arginine repressor/activator protein from Bacillus subtilis.

In Bacillus subtilis the concentration of L-arginine is controlled by the transcriptional regulator AhrC, which interacts with 18 bp DNA operator sites called ARG boxes in the promoters of arginine biosynthetic and catabolic operons. AhrC is a 100 kDa homohexamer, with each subunit having two domains. The C-terminal domains form the core, mediating intersubunit interactions and binding of the co-repressor L-arginine, whilst the N-terminal domains contain a winged helix-turn-helix DNA-binding motif and are arranged around the periphery.

Streptomycin production by Streptomyces griseus can be modulated by a mechanism not associated with change in the adpA component of the A-factor cascade.

In Streptomyces coelicolor, AtrA is an activator of transcription of the actinorhodin cluster-situated regulator gene actII-ORF4. In previous work, we showed that S. coelicolor AtrA binds in vitro to the promoter of S.

Transcriptional activation of the pathway-specific regulator of the actinorhodin biosynthetic genes in Streptomyces coelicolor.

The Streptomyces produce a plethora of secondary metabolites including antibiotics and undergo a complex developmental cycle. As a means of establishing the pathways that regulate secondary metabolite production by this important bacterial genus, the model species Streptomyces coelicolor and its relatives have been the subject of several genetic screens. However, despite the identification and characterization of numerous genes that affect antibiotic production, there is still no overall understanding of the network that integrates the various environmental and growth signals to bring about changes in the expression of biosynthetic genes.