Cytoskeletal Proteins in Bacteria

Bacterial cells have diverse cytoskeletal proteins including eukaryotic homologs of actin, tubulin, and intermediate filaments, along with a unique fourth group, the MinD-ParA proteins.

Actin homologs, MreB and Mbl are found abundantly in rod and spiral-shaped bacteria. These proteins form spiral scaffolds that guide the formation of the peptidoglycan cell wall.

Another actin homolog, ParM, is encoded by non-genomic antibiotic-resistant plasmids in some bacteria and spontaneously assembles into filaments.

During cell division, the growing filament polymers push the plasmid copies apart to the opposite ends of the cell.

Tubulin homologs, FtsZ and BtubA/B, polymerize into filaments or rings.

FtsZ filaments assemble into the Z-ring at the middle of the cell to initiate cell division.

Crescentin subunits are the only intermediate filament-like proteins identified in bacteria. They create a crescent shape in some bacteria like Caulobacter crescentus. In the absence of crescentin subunits, these bacteria turn rod-shaped.

MinD and ParA are ATPases unique to bacterial cells and are required for cell division.