Early cell division protein that marks the future cell division site and supports proper FtsZ ring positioning. Interacts with FtsZ. In newborn cells, forms a ring positioned at mid-cell. Soon after cell division starts and the cells begin elongating, the ring splits into two rings that, as elongation proceeds, move along and mark the future division sites (PubMed:25470041, PubMed:25550321). Targeting to mid-cell does not depend on StkP and/or phosphorylation state (PubMed:25550321). The N-terminal domain is required for interaction with FtsZ. The C-terminal domain efficiently binds peptidoglycan and is required for septal localization. Both domains are required for MapZ cellular function. Phosphorylated on Thr residues by StkP (PubMed:20453092, PubMed:25470041, PubMed:25550321). Both phosphorylated and non-phosphorylated forms of MapZ are required for proper Z-ring formation and dynamics (PubMed:25470041). Phosphorylation probably occurs during the predivisional stage (PubMed:25550321). Deletion mutant exhibits a variety of aberrant cell shapes and sizes, is more sensitive to heat stress and shows lower survival after exposure to oxidative stress (PubMed:25470041, PubMed:25550321). Mutants show severe cell division defects, with cells dividing asymmetrically, generating daughter cells of unequal size (PubMed:25550321). Cells have mispositioned division septa and form grape-like clusters (PubMed:25470041). They exhibit severe alterations of FtsZ ring morphology and localization (PubMed:25470041, PubMed:25550321). FtsA and other cell division proteins are also mislocalized (PubMed:25550321). Belongs to the MapZ family.