The recombination regulator RecX negatively regulates heat-stable antifungal factor (HSAF) biosynthesis in Lysobacter enzymogenes

Bacteria often use multiple transcription factors to regulate specific biological processes. Biosynthesis of heat-stable antifungal factor (HSAF) is regulated by multiple factors in Lysobacter enzymogenes . However, the mechanism of HSAF biosynthesis regulation remains largely unknown. In this study, we screened a potential HSAF biosynthesis regulator, RecX, by a DNA pull-down assay. Deletion of recX resulted in a significant increase in the production of HSAF, and overexpression of recX significantly suppressed HSAF production. Importantly, our results showe that RecX directly binds to the promoter region of the lafB gene to inhibit its transcription and thus decreases HSAF production in L. enzymogenes . These findings reveal the novel mechanism of RecX regulation of antifungal antibiotic production in L. enzymogenes .