Cell-type specificity during development in Bacillus subtilis: the molecular and morphological requirements for sigma...

Area of Science:

• Microbiology
• Molecular Biology
• Cell Biology

Background:

• Bacterial development in Bacillus subtilis involves asymmetric cell division.
• Two key transcription factors, sigma F (forespore) and sigma E (mother cell), regulate gene expression during sporulation.
• Activation of sigma E depends on processing of its precursor, pro-sigma E, a process linked to sigma F activity.

Purpose of the Study:

• To investigate the role of sigma F transcriptional activity in pro-sigma E processing.
• To determine if the sporulation septum is required for pro-sigma E processing.
• To elucidate the signaling pathway regulating sigma E activation during Bacillus subtilis development.

Main Methods:

• Introduction of missense mutations in the sigma F transcription factor to alter its promoter recognition.
• Analysis of pro-sigma E processing and sigma E activity under various mutant conditions.
• Investigating pro-sigma E processing in strains with induced sigma F activity during exponential growth and in pre-septation mutants.

Main Results:

• Mutations in sigma F's promoter recognition abolished pro-sigma E processing, indicating sigma F's transcriptional role.
• Pro-sigma E processing and sigma E activity were high when sigma F was induced during exponential growth.
• Pro-sigma E was efficiently processed in a mutant blocked before septation, demonstrating the septum is not required.

Conclusions:

• Sigma F regulates pro-sigma E processing through its transcriptional activity, not solely by its presence.
• The sporulation septum is not essential for initiating pro-sigma E processing.
• An unknown mechanism likely prevents premature sigma E activation within the forespore.