Effect of SinR Transcriptional Factor on the Expression of Bacilysin Biosynthetic Operon in Bacillus subtilis

摘要

In Bacillus subtilis, bacilysin is a nonribosomally synthesized dipeptide antibiotic composed of L-alanine and L-anticapsin. It is active against a wide range of bacteria and even Candida albicans. The biosynthesis of bacilysin depends on the bacABCDEywfG operon (bac operon) and the adjacent monocistronic gene ywfH. In our previous study, lutR mutation significantly decreased the maximum transcription level of the bacABCDEywfG operon at the onset of stationary phase to about 57% of wild-type level. In this study, we aimed to test the possible effect of global regulator SinR on the expression of the bac operon. For this sinR gene was disrupted in the transcriptional bacA-lacZ fusion bearing strain (OGU1) to generate "sinR::cm bacA::lacZ::erm" bearing strain (OGU1SR). Additionally, we also test whether sinR and lutR gene products affect the bac operon expression mutually due to the close regulatory interactions between LutR and SinR transcriptional factors. For this, ΔsinR-ΔlutR double mutant (sinR::cm lutR::Tn10::spc bacA::lacZ::erm) strain (OGU1SRLR) was constructed. Finally, all of that resulting strains and OGU1 were grown in Perry and Abraham (PA) medium at 37°C and β-galactosidase activities were measured throughout the different stages of growth. β-galactosidase assay results indicated that in the absence of sinR gene product bac operon expression was severely effected. Since, disruption of sinR gene resulted with complete loss of transition state dependent induction of bac operon expression while almost the same bacA-expression profile as the single sinR mutant was detected in the sinR-lutR double mutant.