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FtsK
FtsK is a 1329 amino acid protein involved in bacterial cell division and chromosome segregation. FtsK stands for "Filament temperature sensitive mutant K" because at high temperatures the mutant bacterial cell fails to divide and long filaments develop instead. FtsK, and specifically its C-domain, functions as DNA pump, interacts with other cell division proteins, and intervenes in the regulation of the Xer recombination process.

FtsK Structure
FtsK is a multidomain protein, it is made of three terminals. The N-terminal (FtsKn) is the transmembrane domain. It is involved in cell division and helps in the localization of the division septum. The C-terminal domain (FtsKc) is responsible for chromosome segregation and specifically, chromosome dimer resolution in circular chromosomes. There is an L-terminal (FtsKL) that links the previous ones and extrudes into the cytoplasm from the division septum. The most functional of the domains is the C-terminal which is divided into the three subdomains α, β, and γ. α and β constitute the DNA pump while γ is responsible for translocation by recognizing the KOPS motifs on the DNA strand, it interacts with other cell division proteins and intervenes in the regulation of the Xer process.

FtsK belongs to the AAA (ATPase Associated with various cellular Activities) superfamily and is present in most eubacteria. It is believed that FtsK is a DNA motor protein that moves trapped DNA away from the septum during cell division. (translocation function)

Function in cell division
The orchestrated participation of 10-15 proteins is needed in bacterial cell division, and ftsK is one of the first ones to position itself at mid-cell allowing the recruitment of the other proteins. As first function ftsK stabilizes the divisome before septation occurs. The main role of ftsK in cell division is to stabilize the divisome. Recent research has shed light on the role of ftsK in membrane synthesis and have shown that the L-domain is also important in the building of the septum.

FtsK's role and interaction with XerCD recombinases
Usually, in the presence of a dimers XerCD is introduced to solve it into two monomers. FtsK is responsible for the activity of the Xer recombination reaction. Specifically, ftsKc is summoned if a chromosome dimer is present at the mid-cell point. The Xer mechanism is activated by overexpression of ftsK, therefore it appears (Aussel) that ftsK activates the Xer recombination. FtsK turns on the activity of XerCD by activating XerD and this process requires expenditure of ATP.

FtsK as DNA pump
FtsK is the fastest DNA translocation pump with rates of up to 7 kb s-1 it is also a very efficient one.