Cell density regulates cellular reversal frequency in Myxococcus xanthus

Area of Science:

• Microbiology
• Cell Biology
• Bacterial Chemotaxis

Background:

• Myxococcus xanthus forms fruiting bodies under nutrient limitation.
• Chemotaxis-defective frz mutants show irregular cellular reversals.
• Wild-type M. xanthus cells reverse frequently (approx. every 6 min) individually.

Purpose of the Study:

• Investigate the effect of reversal frequency on M. xanthus aggregation.
• Determine how group size influences cellular reversal frequency during development.

Main Methods:

• Staining M. xanthus cells with a tetrazolium dye.
• Tracking reversal frequencies of single cells and cells within groups.
• Analyzing frz gene mutants and social motility mutants.

Main Results:

• Developmental cells in large groups reverse significantly less than single cells or cells in small groups.
• Reduced reversal frequency correlates with the frz signal transduction system and FrzCD methylation.
• frz or social motility mutants do not exhibit this reduction in reversals.

Conclusions:

• Decreased cellular reversals in larger groups provide a mechanism for M. xanthus aggregation into mounds.
• M. xanthus cells exhibit bidirectional gliding, lacking distinct "head" or "tail" structures.