Bacterial gliding motility: multiple mechanisms for cell movement over surfaces

Area of Science:

• Microbiology
• Bacterial Physiology
• Cellular Motility

Background:

• Bacterial gliding motility is a flagella-independent surface movement observed in diverse bacteria.
• The underlying mechanisms have remained largely enigmatic for nearly two centuries.
• Gliding bacteria are ubiquitous and play significant roles in various ecosystems.

Purpose of the Study:

• To elucidate the diverse mechanisms driving bacterial gliding motility.
• To differentiate between pilus-dependent and potentially pilus-independent gliding pathways.
• To synthesize current understanding from genetic, biochemical, and ultrastructural studies.

Main Methods:

• Comparative analysis of gliding mechanisms across different bacterial species.
• Review of genetic, biochemical, and ultrastructural studies.
• Behavioral observations of bacterial surface translocation.

Main Results:

• Two distinct modes of gliding motility are emerging: pilus-dependent and pilus-independent.
• Type IV pili mediate 'social gliding' in Myxococcus xanthus and Synechocystis gliding, akin to twitching motility.
• Filamentous cyanobacteria, mycoplasmas, Cytophaga-Flavobacterium group, and 'adventurous gliding' in M. xanthus appear to utilize pilus-independent mechanisms.

Conclusions:

• Bacterial gliding motility is not a unified process but involves multiple distinct mechanisms.
• Type IV pili are crucial for certain gliding types, but other pathways exist.
• Further research integrating multiple study approaches is essential to fully understand the machinery behind diverse bacterial gliding.