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  • The EMBO Journal (2006) 25, 596 - 604
  • doi:10.1038/sj.emboj.7600941

Published online: 19 January 2006

RuvAB is essential for replication forks reversal in certain replication mutants

Zeynep Baharoglu1,2, Mirjana Petranovic1,a, Maria-Jose Flores1,b and Bénédicte Michel1,2

  1. Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas Cedex, France
  2. Present address: Centre de génétique Moléculaire, CNRS Bâtiment 26, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France

Correspondence to:

Bénédicte Michel, Centre de génétique Moléculaire, CNRS Bâtiment 26, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France. Tel.: +33 1 69 82 32 29; Fax: +33 1 69 82 31 40; E-mail: benedicte.michel@cgm.cnrs-gif.fr

aPresent address: Department of Molecular Genetics, Ruder Boskovic Institute, 10001 Zagreb, Croatia

bUnité d'Ecologie et de Physiologie du Système Digestif INRA 78352, Jouy-en-Josas Cedex, France

Received 24 October 2005; Accepted 14 December 2005

Inactivated replication forks may be reversed by the annealing of leading- and lagging-strand ends, resulting in the formation of a Holliday junction (HJ) adjacent to a DNA double-strand end. In Escherichia coli mutants deficient for double-strand end processing, resolution of the HJ by RuvABC leads to fork breakage, a reaction that we can directly quantify. Here we used the HJ-specific resolvase RusA to test a putative role of the RuvAB helicase in replication fork reversal (RFR). We show that the RuvAB complex is required for the formation of a RusA substrate in the polymerase III mutants dnaEts and holD, affected for the Pol III catalytic subunit and clamp loader, and in the helicase mutant rep. This finding reveals that the recombination enzyme RuvAB targets forks in vivo and we propose that it directly converts forks into HJs. In contrast, RFR occurs in the absence of RuvAB in the dnaNts mutant, affected for the processivity clamp of Pol III, and in the priA mutant, defective for replication restart. This suggests alternative pathways of RFR.

  • Keywords:

    • DNA repair,
    • genome stability,
    • helicase,
    • recombination,
    • replication restart