A dynamically assembled cell wall synthesis machinery buffers cell growth.

Area of Science:

• Microbiology
• Cell Biology
• Biophysics

Background:

• Protein complex assembly is crucial for coordinating cellular processes.
• Bacterial cell wall synthesis requires coordination between enzymes and the cytoskeleton.
• Previous models proposed stable complexes for bacterial growth coordination.

Purpose of the Study:

• To investigate the interaction dynamics between bacterial actin homolog MreB and cell wall enzyme PBP2.
• To elucidate the mechanism of spatial and temporal coordination in bacterial growth.

Main Methods:

• Utilized single-molecule tracking to observe MreB and PBP2 movement.
• Analyzed motion timescales and characteristic movements of individual protein molecules.

Main Results:

• MreB and PBP2 exhibit drastically different motion patterns and timescales.
• PBP2 interacts with the synthesis machinery via transient associations, not stable complexes.
• Bacterial growth remains robust despite significant fluctuations in PBP2 abundance.

Conclusions:

• Dynamic association, rather than stable complex formation, is key for PBP2 function.
• This dynamic model explains growth robustness against component variability and defects.
• Transient interactions offer an efficient strategy for spatiotemporal coordination in biological systems.