Dissection of a functional interaction between the DNA translocase, FtsK, and the XerD recombinase.
Successful bacterial circular chromosome segregation requires that any dimeric chromosomes, which arise by crossing over during homologous recombination, are converted to monomers. Resolution of dimers to monomers requires the action of the XerCD site-specific recombinase at dif in the chromosome replication terminus region. This reaction requires the DNA translocase, FtsK(C), which activates dimer resolution by catalysing an ATP hydrolysis-dependent switch in the catalytic state of the nucleoprotein recombination complex. We show that a 62-amino-acid fragment of FtsK(C) interacts directly with the XerD C-terminus in order to stimulate the cleavage by XerD of BSN, a dif-DNA suicide substrate containing a nick in the 'bottom' strand. The resulting recombinase-DNA covalent complex can undergo strand exchange with intact duplex dif in the absence of ATP. FtsK(C)-mediated stimulation of BSN cleavage by XerD requires synaptic complex formation. Mutational impairment of the XerD-FtsK(C) interaction leads to reduction in the in vitro stimulation of BSN cleavage by XerD and a concomitant deficiency in the resolution of chromosomal dimers at dif in vivo, although other XerD functions are not affected.
Division of Molecular Genetics, Department Biochemistry, University of Oxford, UK.
James
J
Yates
Ivailo
I
Zhekov
Rachel
R
Baker
Bjørn
B
Eklund
David J
DJ
Sherratt
Lidia K
LK
Arciszewska
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D020090:Chromosome Segregation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics; D019426:Integrases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins; C473360:XerC protein, E coli; D019426:Integrases; C473361:XerD protein, E coli