Protein with ATPase activity which forms pole-to-pole filaments in vivo, probably with MamK. Efficient filament formation requires MamK. Probably promotes turnover of MamK filaments, by providing a monomer pool (PubMed:24957623). In vivo, in the absence of its paralog MamK, forms thin filaments from pole to pole (PubMed:20161777). In vitro forms straight filaments and bundles in the absence of ATP. Filament formation is triggered by KCl and MgCl(2); polymerizes more slowly and makes thinner filaments than MamK (PubMed:20161777). Expression in E.coli yields a filament in the cell's longitudinal axis; the protein nucleates at one pole or the cell septum (PubMed:20161777). ATP + H2O = ADP + H(+) + phosphate Forms cytoplasmic filament polymers (PubMed:20161777, PubMed:24957623). Forms filaments with MamK (PubMed:24957623). Protein forms filaments extending along most of the cell associated with its inner curvature, in the correct position to be filaments that are seen associated with magnetosomes (PubMed:20161777). Colocalizes in filaments with paralog MamK (PubMed:24957623). Expressed during exponential phase in static growth conditions in the presence and absence of the mamK gene (PubMed:20161777). Expressed during late exponential phase in the presence and absence of the mamK gene (PubMed:24957623). About 40% reduction in magnetosome alignment; a double mamK-mamK-like deletion has a 65% reduction in magnetosome alignment. The single mamK-like deletion has no effect on MamK turnover rates. This bacteria makes up to 20 cubo-octahedral magnetosomes of about 45 nm in diameter which contain membrane-bound crystals of magnetite (Fe(3)O(4)). Despite the presence of Ala-141 (where Glu is expected) this protein has ATPase activity. Encoded in an approximately 22 kb magnetotaxis genomic islet separate from the large magnetosome island. Belongs to the FtsA/MreB family. MamK subfamily.