Gene encoding the 37,000-dalton minor sigma factor of Bacillus subtilis RNA polymerase: isolation, nucleotide...

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacillus subtilis RNA polymerase utilizes various sigma factors to regulate gene expression.
• The cryptic sigma-37 (encoded by rpoF) is a minor sigma factor with an unknown primary function.

Purpose of the Study:

• To isolate and characterize the Bacillus subtilis rpoF gene.
• To determine the function of the sigma-37 factor in B. subtilis.

Main Methods:

• Antibody screening of a lambda gt11 expression library to isolate rpoF gene fragments.
• DNA sequencing and homology analysis to confirm gene identity and predict protein product.
• Gene disruption via plasmid integration and transduction to create rpoF null mutants.

Main Results:

• A 901-bp fragment encoding the C-terminal half of sigma-37 was isolated and used to clone the full rpoF gene.
• DNA sequencing revealed rpoF encodes a 264-residue protein homologous to other sigma factors and suggested potential gene clustering.
• An rpoF null mutation did not affect cell growth or sporulation in rich medium.

Conclusions:

• The rpoF gene has been cloned and characterized.
• Sigma-37 is not essential for B. subtilis growth or sporulation under tested conditions.
• Sigma-37 likely regulates a subset of genes not directly involved in sporulation.