Table 2.
Functional diversification of MreB paralogs in bacteria
| Category | Typical Species | Protein | Classical Function | Acquired Function | Driving Deficiency | Evolutionary Driver | |
|---|---|---|---|---|---|---|---|
| Rod-shaped bacteria | E. coli, B. subtilis | MreB, Mbl, MreBH | Cell shape maintenance and peptidoglycan synthesis coordination | Chromosome segregation via RNA polymerase (RNAP) coupling and replisome anchoring | None (ancestral function) | Optimization of cytoskeletal multitasking | |
| Wall-less bacteria | Spiroplasma | MreB1–MreB7 (such as MreB5) | Helical motility, kink propagation, and membrane deformation | Absence of cell wall | Loss of rigid wall enables mechanical force-driven motility | ||
| FtsZ-deficient pathogens | Chlamydia | MreB | Peptidoglycan ring assembly and lipid II synthase recruitment | FtsZ-independent division and divisome scaffolding | Absence of FtsZ | Genome reduction in obligate intracellular pathogens | |
| Morphologically plastic bacteria | S. coelicolor | MreB | Vegetative hyphae shape | Spore-specific wall remodeling | Developmental reprogramming | Lifecycle adaptation (hyphae to spores) | |
| Morphologically plastic bacteria | C. crescentus | MreB | Cell elongation | Stalk synthesis | Localized divisome redistribution | Niche adaptation (polar growth) | |
| Pathogen virulence | S. flexneri | MreB | Cell shape maintenance | Actin tail formation (via IcsA) | Host invasion mechanism | Pathoadaptation for intercellular spread | |