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. Required for activation of the Xer recombinase, allowing activation of chromosome unlinking by recombination (By similarity). Homohexamer. Forms a ring that surrounds DNA (By similarity). Located at the septum. During persistent infection, while it is induced one day after infection, but transcription, it is severely down-regulated. 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 form the DNA pump, and the gamma subdomain is a regulatory subdomain (By similarity). Belongs to the FtsK/SpoIIIE/SftA family.