The ClpY-ClpQ protease regulates multicellular development in Bacillus subtilis.

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Genetics

Background:

• ATP-dependent proteases like ClpYQ are vital for protein homeostasis and regulation in bacteria.
• While ClpYQ function is known in Gram-negative bacteria, its role in Gram-positive species remains largely unexplored.

Purpose of the Study:

• To investigate the biological function and regulation of the ClpYQ protease in the Gram-positive bacterium Bacillus subtilis.
• To elucidate the role of ClpYQ in bacterial multicellular development, including biofilm formation and motility.

Main Methods:

• Generated a ΔclpYQ deletion mutant in Bacillus subtilis.
• Utilized global proteomic analysis (isobaric tags for relative and absolute quantification - iTRAQ) to assess protein abundance changes.
• Employed Western immunoblotting to validate protein level alterations.

Main Results:

• The ΔclpYQ mutant exhibited enhanced early biofilm formation and significantly impaired swarming motility.
• Reduced production of secreted γ-poly-dl-glutamic acid (γ-PGA) was observed in the mutant, impacting colony mucoidy.
• Proteomic analysis revealed decreased abundance of proteins involved in motility, chemotaxis, and γ-PGA production in the ΔclpYQ mutant.
• A modest reduction in the biofilm repressor SinR was detected, potentially explaining altered biofilm regulation.

Conclusions:

• ClpYQ protease plays a significant role in the multicellular development of Bacillus subtilis, primarily influencing biofilm formation and swarming motility.
• Unlike in Escherichia coli, ClpYQ is not essential for the heat-shock response in Bacillus subtilis and Bacillus cereus.