Identification of metabolism pathways directly regulated by sigma(54) factor in Bacillus thuringiensis.

ABSTRACT: Sigma(54) (?(54)) regulates nitrogen and carbon utilization in bacteria. Promoters that are ?(54)-dependent are highly conserved and contain short sequences located at the -24 and -12 positions upstream of the transcription initiation site. ?(54) requires regulatory proteins known as bacterial enhancer-binding proteins (bEBPs) to activate gene transcription. We show that ?(54) regulates the capacity to grow on various nitrogen sources using a Bacillus thuringiensis HD73 mutant lacking the sigL gene encoding ?(54) (?sigL). A 2-fold-change cutoff and a false discovery rate cutoff of P < 0.05 were used to analyze the DNA microarray data, which revealed 255 genes that were downregulated and 121 that were upregulated in the ?sigL mutant relative to the wild-type HD73 strain. The ?(54) regulon (stationary phase) was characterized by DNA microarray, bioinformatics, and functional assay; 16 operons containing 47 genes were identified whose promoter regions contain the conserved -12/-24 element and whose transcriptional activities were abolished or reduced in the ?sigL mutant. Eight ?(54)-dependent transcriptional bEBPs were found in the Bt HD73 genome, and they regulated nine ?(54)-dependent promoters. The metabolic pathways activated by ?(54) in this process have yet to be identified in Bacillus thuringiensis; nonetheless, the present analysis of the ?(54) regulon provides a better understanding of the physiological roles of ? factors in bacteria.

SUBMITTER: Peng Q 

PROVIDER: S-EPMC4428206 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature