title: Double-stranded DNA translocation: structure and mechanism of hexameric FtsK.
abstract: FtsK is a DNA translocase that coordinates chromosome segregation and cell division in bacteria. In addition to its role as activator of XerCD site-specific recombination, FtsK can translocate double-stranded DNA (dsDNA) rapidly and directionally and reverse direction. We present crystal structures of the FtsK motor domain monomer, showing that it has a RecA-like core, the FtsK hexamer, and also showing that it is a ring with a large central annulus and a dodecamer consisting of two hexamers, head to head. Electron microscopy (EM) demonstrates the DNA-dependent existence of hexamers in solution and shows that duplex DNA passes through the middle of each ring. Comparison of FtsK monomer structures from two different crystal forms highlights a conformational change that we propose is the structural basis for a rotary inchworm mechanism of DNA translocation.
authors.affiliation: Division of Molecular Genetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Massey
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Mercogliano
authors.forename: James
authors.initials: J
authors.lastname: Yates
authors.forename: David J
authors.initials: DJ
authors.lastname: Sherratt
authors.forename: Jan
authors.initials: J
authors.lastname: Löwe
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D018360:Crystallography, X-Ray; D004265:DNA Helicases / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D006868:Hydrolysis; D019426:Integrases / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D008957:Models, Genetic; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D020365:RNA Helicases / Q000378:metabolism; D011938:Rec A Recombinases / Q000378:metabolism; D011995:Recombination, Genetic
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins; D000255:Adenosine Triphosphate; D019426:Integrases; D011938:Rec A Recombinases; D004265:DNA Helicases; D020365:RNA Helicases