Processing of a sporulation sigma factor in Bacillus subtilis: how morphological structure could control gene...

Area of Science:

• Microbiology
• Molecular Biology
• Developmental Biology

Background:

• Bacillus subtilis sporulation couples morphological changes with gene expression timing.
• Sigma E (σE) is a key developmental sigma factor, synthesized as an inactive precursor (pro-σE).
• Early transcriptional control relies on the activation of pro-σE.

Purpose of the Study:

• To investigate the role of the spoIIGA gene in pro-sigma E processing.
• To understand the mechanism linking morphological development to sigma E activation.
• To identify the trigger for SpoIIGA's pro-sigma E processing activity.

Main Methods:

• Genetic analysis of spoIIGA mutations in Bacillus subtilis.
• Expression studies of sigE and spoIIGA in vegetative cells.
• Analysis of SpoIIGA polypeptide structure and synthesis timing.

Main Results:

• Mutations in spoIIGA prevent pro-sigma E processing.
• Co-expression of spoIIGA and sigE in vegetative cells activates sigma E-controlled promoters.
• SpoIIGA, a membrane protein, is synthesized before its processing activity is detected.
• SpoIIGA processing activity appears to be triggered by the sporulation septum.

Conclusions:

• SpoIIGA possesses pro-sigma E processing activity.
• The sporulation septum, dependent on spoIIAA and spoIIE, likely triggers SpoIIGA activity.
• This mechanism provides a direct link between a morphological structure and developmental gene expression regulation.