Essential cell division protein that coordinates cell division and chromosome segregation. The N-terminus is involved in assembly of the cell-division machinery. The C-terminus functions as a DNA motor that moves dsDNA in an ATP-dependent manner towards the dif recombination site, which is located within the replication terminus region. Translocation stops specifically at Xer-dif sites, where FtsK interacts with the Xer recombinase, allowing activation of chromosome unlinking by recombination. FtsK orienting polar sequences (KOPS) guide the direction of DNA translocation. FtsK can remove proteins from DNA as it translocates, but translocation stops specifically at XerCD-dif site, thereby preventing removal of XerC and XerD from dif. Stoppage of translocation is accompanied by a reduction in ATPase activity. Also stimulates topoisomerase 4 activity. Required for the targeting of FtsQ, FtsL and FtsI to the septum. Homohexamer. Forms a ring that surrounds DNA. Interacts with FtsZ, FtsQ, FtsL and FtsI. Located at the septum. Colocalizes with FtsZ. ZipA, FtsZ and FtsA, but not FtsI and FtsQ are required to target it to the septum. Induced by DNA-damaging agents. Consists of an N-terminal domain, which is sufficient for the localization to the septal ring and is required for cell division, followed by a linker domain, and a C-terminal domain, which forms the translocation motor involved in chromosome segregation. The C-terminal domain can be further subdivided into alpha, beta and gamma subdomains. The alpha and beta subdomains multimerise to produce a hexameric ring, contain the nucleotide binding motif and form the DNA pump. The gamma subdomain is a regulatory subdomain that controls translocation of DNA by recognition of KOPS motifs and interacts with XerD recombinase. Belongs to the FtsK/SpoIIIE/SftA family.