Protein with ATPase activity which forms dynamic cytoplasmic filaments that are involved in sorting, concatenating and/or correctly positioning of magnetosomes in the cell. Not absolutely necessary for assembly of short chains (PubMed:20487281, PubMed:22586444, PubMed:27733152). Filaments grow from the both cell poles towards midcell, and are probably disassembled at the other end of the cell, a process known as treadmilling (PubMed:27733152). Polymerizes in the presence of ATP, GTP or a non-hydrolyzable ATP analog (PubMed:22586444). Required for correct segregation and positioning of magnetosomes following cell division (PubMed:22026731, PubMed:27733152). ATP + H2O = ADP + H(+) + phosphate Filament dynamics depend partially on MamJ. Forms cytoplasmic filaments (PubMed:17601786, PubMed:20487281, PubMed:22026731, PubMed:22586444, PubMed:24272781). Interacts with MamJ (PubMed:17601786). Forms filaments in the absence of other magnetosome proteins and in E.coli (PubMed:20487281). Filament formation in vitro requires ATP, GTP or a non-hydrolyzable ATP analog (PubMed:22586444). Tagged protein forms straight lines 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:17601786, PubMed:20487281). The exact pattern depends on the N- or C-terminal location of the tag and the length of the linker to the rest of the protein (PubMed:20487281). Individual filaments are 3-6 nm in diameter and 0.5-1 nm in length and occasionally form bundles. Filaments are in close proximity to magnetosome membranes. Most are near midcell, however some extend to nearly the cell pole; they are not seen in a deletion mutant (PubMed:20487281). Filaments do not colocalize with FtsZ-like (also called FtsZm) foci (PubMed:24272781). Part of the probable 17 gene mamAB operon. Non-polar single gene deletion has wild-type growth and motility. Has half the number of magnetosomes which are mostly incorrectly positioned and of lower chain length; magnetite crystals and magnetosome morphology are normal. No magnetosome-associated filaments are seen (PubMed:20487281, PubMed:27733152). Incorrect subcellular location of MamJ (PubMed:20487281). Incorrect positioning of magnetosomes in dividing cells, leads to uneven distribution of magnetosome crystals (PubMed:22026731, PubMed:27733152). Deletion of 3 consecutive genes (mamJ, mamK, mamL) leads to cells devoid of magnetosomes or a magnetic response (PubMed:22043287). Deletion of approximately 80 kb of DNA, including this operon, leads to cells that are non-magnetic, lack internal membrane systems, grow poorly, have reduced mobility and take-up and accumulate iron poorly (PubMed:13129949). This bacteria makes up to 60 cubo-octahedral magnetosomes of about 45 nm in diameter which contain membrane-bound crystals of magnetite (Fe(3)O(4)). Expression of just the minimal mamAB gene cluster (MGMSRv2__2365 to MGMSRv2__2381), including this gene, is sufficient to form a minimal magnetosome chain with small magnetite particles. In the related bacteria M.magneticum strain AMB the magnetosome position remains stable during cytokinesis. Belongs to the FtsA/MreB family. MamK subfamily. It is uncertain whether Met-1 or Met-14 is the initiator. Truncated N-terminus.