Autoregulation of antibiotic biosynthesis by binding of the end product to an atypical response regulator.

In bacteria, many "atypical" response regulators (ARRs) lack the conserved residues important for phosphorylation by which typical response regulators switch their output response, suggesting the existence of alternative regulatory mechanisms. However, such mechanisms have not been established. JadR1, an OmpR-type ARR of Streptomyces venezuelae, appears to activate the transcription of jadomycin B (JdB) biosynthetic genes while repressing its own gene. JadR1 activities were inhibited in cells induced to produce JdB, which was found to bind directly to the N-terminal receiver domain of JadR1, causing JadR1 to dissociate from target promoters. The activity of a NarL-type ARR, RedZ, that regulates production of another antibiotic was likewise modulated by the end product (undecylprodigisines), implying that end-product-mediated control of antibiotic pathway-specific ARRs may be widespread. These results could prove relevant to knowledge-based improvements in yield of commercially important antibiotics.