Analysis of DNA supercoil induction by FtsK indicates translocation without groove-tracking

Publication Type:

Journal Article

Source:

NATURE STRUCTURAL & MOLECULAR BIOLOGY, NATURE PUBLISHING GROUP, Volume 12, Number 5, 345 PARK AVENUE SOUTH, NEW YORK, NY 10010-1707 USA, p.436-440 (2005)

DOI:

10.1038/nsmb926

Keywords:

CHROMOSOME DIMER RESOLUTION; ESCHERICHIA-COLI; HELIX; MECHANISM; MOLECULE; RECOMBINATION; ROTATION; TEMPLATE; TOPOISOMERASES; TRANSCRIPTION

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 ∼ 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.