title: Analysis of DNA supercoil induction by FtsK indicates translocation without groove-tracking.
abstract: FtsK is a bacterial protein that translocates DNA in order to transport chromosomes within the cell. During translocation, DNA's double-helical structure might cause a relative rotation between FtsK and the DNA. We used a single-molecule technique to quantify this rotation by observing the supercoils induced into the DNA during translocation of an FtsK complex. We find that FtsK induces approximately 0.07 supercoils per DNA helical pitch traveled. This rate indicates that FtsK does not track along DNA's groove, but it is consistent with our previous estimate of FtsK's step size. We show that this rate of supercoil induction is markedly near to the ideal value that would minimize in vivo disturbance to the chromosomal supercoil density, suggesting an origin for the unusual rotational behavior of FtsK.
authors.affiliation: Laboratoire de Physique Statistique et Département de Biologie, Ecole Normale Supérieure, UMR8550 associé au CNRS et aux Universités Paris VI et VII, Paris, France.
authors.forename: Omar A
authors.initials: OA
authors.lastname: Saleh
authors.forename: Sarah
authors.initials: S
authors.lastname: Bigot
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Barre
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Allemand
mesh_terms: D004278:DNA, Superhelical / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*
chemical_list: D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins