Interplay between recombination, cell division and chromosome structure during chromosome dimer resolution in Escherichia coli.
Chromosome dimers form in bacteria by recombination between circular chromosomes. Resolution of dimers is a highly integrated process involving recombination between dif sites catalysed by the XerCD recombinase, cell division and the integrity of the division septum-associated FtsK protein and the presence of dif inside a restricted region of the chromosome terminus, the dif activity zone (DAZ). We analyse here how these phenomena collaborate. We show that (i) both inter- and intrachromosomal recombination between dif sites are activated by their presence inside the DAZ; (ii) the DAZ-specific activation only occurs in conditions supporting the formation of chromosome dimers; (iii) overexpression of FtsK leads to a general increase in dif recombination irrespective of dif location; (iv) overexpression of FtsK does not improve the ability of dif sites inserted outside the DAZ to resolve chromosome dimers. Our results suggest that the formation of an active XerCD-FtsK-dif complex is restricted to when a dimer is present, the features of chromosome organization that determine the DAZ playing a central role in this control.
Laboratoire de Microbiologie et de Génétique Moléculaire du CNRS, 118 route de Narbonne, 31062 Toulouse Cedex, France.
K
K
Pérals
H
H
Capiaux
J B
JB
Vincourt
J M
JM
Louarn
D J
DJ
Sherratt
F
F
Cornet
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D002455:Cell Division; D002876:Chromosomes, Bacterial; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins; D011938:Rec A Recombinases