The GTPase, CpgA(YloQ), a putative translation factor, is implicated in morphogenesis in Bacillus subtilis

Area of Science:

• Microbiology
• Molecular Biology
• Structural Biology

Background:

• YloQ from Bacillus subtilis is an essential nucleotide-binding protein with an unidentified function.
• Small bacterial GTPases play crucial roles in cellular processes.
• The unique G motif order in YloQ suggested a novel GTPase.

Purpose of the Study:

• To characterize the function and properties of YloQ.
• To rename YloQ to CpgA (circularly permuted GTPase) based on its GTPase activity.
• To investigate the role of CpgA in Bacillus subtilis cell morphology and growth.

Main Methods:

• Over-expression and purification of YloQ in E. coli.
• GTPase activity assays.
• Gel filtration and ultracentrifugation to analyze protein dimerization.
• Gene deletion and complementation studies in Bacillus subtilis using inducible promoters.
• Crystal structure determination of CpgA.

Main Results:

• Purified YloQ exhibited low GTPase activity, leading to its reclassification as CpgA.
• CpgA formed stable dimers concentration-dependently, independent of GTP.
• Depletion of CpgA in Bacillus subtilis resulted in significantly reduced growth and perturbed cell morphology (swollen, bent, 'curly' shapes).
• Complementation with CpgA restored normal growth and cell shape.
• The crystal structure of CpgA suggests a role in translation initiation.

Conclusions:

• CpgA is an essential, low-abundance GTPase in Bacillus subtilis.
• CpgA plays a critical role in maintaining cell shape and promoting growth.
• Evidence suggests CpgA functions as a translation initiation factor, potentially for proteins involved in cell shape maintenance.