Forms membrane-associated dynamic filaments that are essential for cell shape determination (PubMed:11290328, PubMed:19659933). Acts by regulating cell wall synthesis and cell elongation, and thus cell shape (PubMed:19659933). A feedback loop between cell geometry and Mbl localization may maintain elongated cell shape by targeting cell wall growth to regions of negative cell wall curvature (By similarity). Filaments rotate around the cell circumference in concert with the cell wall synthesis enzymes. The process is driven by the cell wall synthesis machinery and does not depend on Mbl polymerization (PubMed:21636745, PubMed:21636744). Organizes peptidoglycan synthesis in the lateral cell wall (PubMed:19659933). Also required for proper chromosome segregation (PubMed:14588250). Forms polymers (PubMed:11290328, PubMed:19659933). Forms a complex with MreB and MreBH (PubMed:17064365, PubMed:19659933). Interacts with MreC (PubMed:17064365). Membrane-associated (PubMed:17064365). Localizes in the form of helical filaments that run the length of the cell (PubMed:11290328). Colocalizes with MreB, MreBH and MreC (PubMed:16950129, PubMed:17064365). Mutants are bent and twisted at irregular angles (PubMed:11290328). Depletion leads to a strong defect in chromosome segregation (PubMed:14588250). B.subtilis has three MreB paralogs: MreB, Mbl and MreBH. All paralogs have the ability to support rod-shaped cell growth normal conditions. The multiplicity of paralogs becomes important under stress conditions. They are probably used to allow cells to maintain proper growth and morphogenesis under changing conditions. Belongs to the FtsA/MreB family.