1. Cancer Research UK Clare Hall Laboratories, The London Research Institute, Blanche Lane, South Mimms, Potters Bar, Herts. EN6 3LD, UK
2. National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
3. Sections of Microbiology and Molecular & Cellular Biology, Center for Genetics and Development, University of California at Davis, Davis, California 95616, USA
4. These authors contributed equally to this work

Correspondence to: Dale B. Wigley¹ Email: dale.wigley@cancer.org.uk
The coordinates have been deposited at the Protein Databank with accession code 1W36.

Abstract

RecBCD is a multi-functional enzyme complex that processes DNA ends resulting from a double-strand break. RecBCD is a bipolar helicase that splits the duplex into its component strands and digests them until encountering a recombinational hotspot (Chi site). The nuclease activity is then attenuated and RecBCD loads RecA onto the 3' tail of the DNA. Here we present the crystal structure of RecBCD bound to a DNA substrate. In this initiation complex, the DNA duplex has been split across the RecC subunit to create a fork with the separated strands each heading towards different helicase motor subunits. The strands pass along tunnels within the complex, both emerging adjacent to the nuclease domain of RecB. Passage of the 3' tail through one of these tunnels provides a mechanism for the recognition of a Chi sequence by RecC within the context of double-stranded DNA. Gating of this tunnel suggests how nuclease activity might be regulated.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.