Evolution of signalling in the sporulation phosphorelay

Area of Science:

• Microbiology
• Molecular Biology
• Evolutionary Biology

Background:

• Two-component and phosphorelay systems act as environmental sensors in microbes, regulating gene expression based on their ecological niche.
• Understanding how related bacteria adapt their signal transduction pathways to different environments is crucial for evolutionary studies.

Purpose of the Study:

• To investigate the evolutionary changes in the sporulation phosphorelay system across different Bacillus species inhabiting distinct environments.
• To identify conserved and divergent regions within phosphorelay proteins and their implications for environmental adaptation.

Main Methods:

• Comparative analysis of primary amino acid sequences of phosphorelay proteins from Bacillus subtilis, Bacillus halodurans, Bacillus anthracis, and Bacillus stearothermophilus.
• Utilizing known structural and interactive properties of Bacillus subtilis phosphorelay proteins to infer functional conservation and divergence.

Main Results:

• Interaction surfaces between phosphorelay proteins and between proteins and DNA are highly conserved across species, resisting evolutionary change.
• Signal-sensing domains of sporulation sensor kinases show significant variation in size and composition, indicating rapid adaptation.
• Catalytic domains of sensor kinases and other phosphorelay proteins exhibit high homology, suggesting functional constraint.

Conclusions:

• Environmental adaptation in bacteria involves rapid evolution of signal-sensing domains to optimize environmental sensing.
• Conserved protein-protein and protein-DNA interaction surfaces are critical for maintaining the integrity of the phosphorelay system.
• Anaerobic bacteria like Clostridia may utilize direct phosphorylation of Spo0A by sensor kinases instead of a phosphorelay system.