Reversing cell polarity: evidence and hypothesis

Area of Science:

• Microbiology
• Cell Biology
• Biophysics

Background:

• Myxobacteria exhibit complex multicellular behaviors like swarming and fruiting body formation.
• Cellular movement is powered by gliding motility, involving distinct engine complexes.
• Understanding the regulation of cell polarity and movement reversals is key to myxobacterial development.

Purpose of the Study:

• To propose a model for how myxobacteria control cell polarity and movement reversals.
• To elucidate the molecular mechanisms underlying the switch in gliding engine orientation.
• To explain how changes in reversal patterns facilitate swarming and fruiting body development.

Main Methods:

• Hypothetical model development based on existing knowledge of myxobacterial motility.
• Integration of known components like A-engines, pili, Mgl G-protein switch, and Frizzy proteins.
• Analysis of how oscillatory circuits and external signals influence reversal frequency and patterns.

Main Results:

• A hypothesis is presented where gliding engines are disassembled and reassembled at the opposite pole during reversals.
• The Mgl G-protein switch is proposed to control engine polarity, driven by a Frizzy protein oscillator.
• Cellular behavior transitions from occasional reversals during growth (swarming) to regular, prolonged reversals during development (fruiting).

Conclusions:

• The proposed model provides a framework for understanding the coordinated movement and developmental transitions in myxobacteria.
• The interplay between G-protein signaling, Frizzy protein oscillations, and engine dynamics governs cell polarity and motility.
• Regulated reversals are crucial for both individual cell movement and the collective behaviors leading to multicellular structures.