title: FtsK activities in Xer recombination, DNA mobilization and cell division involve overlapping and separate domains of the protein.
abstract: Escherichia coli FtsK is a multifunctional protein that couples cell division and chromosome segregation. Its N-terminal transmembrane domain (FtsK(N)) is essential for septum formation, whereas its C-terminal domain (FtsK(C)) is required for chromosome dimer resolution by XerCD-dif site-specific recombination. FtsK(C) is an ATP-dependent DNA translocase. In vitro and in vivo data point to a dual role for this domain in chromosome dimer resolution (i) to directly activate recombination by XerCD-dif and (ii) to bring recombination sites together and/or to clear DNA from the closing septum. FtsK(N) and FtsK(C) are separated by a long linker region (FtsK(L)) of unknown function that is highly divergent between bacterial species. Here, we analysed the in vivo effects of deletions of FtsK(L) and/or of FtsK(C), of swaps of these domains with their Haemophilus influenzae counterparts and of a point mutation that inactivates the walker A motif of FtsK(C). Phenotypic characterization of the mutants indicated a role for FtsK(L) in cell division. More importantly, even though Xer recombination activation and DNA mobilization both rely on the ATPase activity of FtsK(C), mutants were found that can perform only one or the other of these two functions, which allowed their separation in vivo for the first time.
authors.affiliation: Laboratoire de Microbiologie et de Génétique moléculaire du CNRS, 118 route de Narbonne, 31062 Toulouse Cedex 4, France.
authors.forename: Sarah
authors.initials: S
authors.lastname: Bigot
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Corre
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Louarn
authors.forename: François
authors.initials: F
authors.lastname: Cornet
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Barre
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D002876:Chromosomes, Bacterial; D018920:Coculture Techniques; D004247:DNA / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006193:Haemophilus influenzae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins; D004247:DNA