Promoter for a developmentally regulated gene in Bacillus subtilis

Area of Science:

• Molecular Biology
• Microbial Genetics
• Bacterial Development

Background:

• Bacillus subtilis undergoes sporulation, a complex developmental process.
• Specific regulatory genes (spo0 loci) control the initiation of sporulation.
• Gene transcription during sporulation is developmentally regulated.

Purpose of the Study:

• To determine the nucleotide sequence of the promoter for a developmentally controlled B. subtilis gene (0.4 kb gene).
• To investigate the role of RNA polymerase sigma factors in regulating this gene's transcription.
• To elucidate the promoter structure and its implications for developmental regulation.

Main Methods:

• Nucleotide sequencing of the promoter region.
• In vitro transcription assays using purified RNA polymerase and sigma factors.
• S1 nuclease mapping, runoff transcription, and dinucleotide priming to identify transcription start sites.
• Construction and analysis of in vitro deletion mutations within the promoter region.

Main Results:

• The 0.4 kb gene promoter is recognized by sigma 37 and sigma 29, but not sigma 55.
• Dual transcription start sites, approximately 10 bp apart, were identified for sigma 37-directed transcription.
• Deletion analysis revealed an AT-rich region essential for downstream transcription initiation and an upstream start site.

Conclusions:

• The promoter structure of the 0.4 kb gene, with its dual start sites and specific AT-rich element, is critical for developmentally regulated transcription in B. subtilis.
• Different forms of RNA polymerase containing sigma 37 exhibit distinct preferences for transcription start sites.
• These findings provide insights into the mechanisms governing gene expression during bacterial development and sporulation.