Two-Component Response Regulator DegU Controls the Expression of Bacilysin in Plant-Growth-Promoting Bacterium Bacillus amyloliquefaciens FZB42

Abstract

The plant-growth-promoting-rhizobacteria Bacillus amyloliquefaciens FZB42 possess an enormous potential to synthesize a wide range of antimicrobial, antiviral and nematocidal compounds. One of them, the dipeptide antibiotic bacilysin, is synthesized by FZB42 during exponential growth. Here, we have demonstrated that bacilysin is positively regulated by the two-component response regulator DegU at the transcriptional level. In addition, ScoC (Hpr), a transition state regulator, negatively controlled expression of the bacA gene, which is the first gene within the bacilysin operon. Both DegU and ScoC were bound directly at the bacA promoter region. Furthermore, a monocistronic gene located in close vicinity of the bac operon and essential for bacilysin production, ywfH, was also regulated by DegU. Transcription of the bac operon and of the ywfH gene in B. amyloliquefaciens FZB42 was positively controlled by the DegU global regulator protein. The role of interactions within a ternary complex formed by the antagonistically acting regulators DegU and ScoC as well as the bacA promoter sequence remains to be elucidated.