RecBCD enzyme is a bipolar DNA helicase

Mark S Dillingham; Maria Spies; Stephen C Kowalczykowski

doi:10.1038/nature01673

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Journal article

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RecBCD enzyme is a bipolar DNA helicase

Mark S Dillingham, Maria Spies and Stephen C Kowalczykowski

Nature (London), Vol.423(6942), pp.893-897

06/19/2003

DOI: 10.1038/nature01673

PMID: 12815438

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Abstract

Escherichia coli RecBCD is a heterotrimeric helicase/nuclease that catalyses a complex reaction in which double-strand breaks in DNA are processed for repair by homologous recombination. For some time it has been clear that the RecB subunit possesses a 3' --> 5' DNA helicase activity, which was thought to drive DNA translocation and unwinding in the RecBCD holoenzyme. Here we show that purified RecD protein is also a DNA helicase, but one that possesses a 5' --> 3' polarity. We also show that the RecB and RecD helicases are both active in intact RecBCD, because the enzyme remains capable of processive DNA unwinding when either of these subunits is inactivated by mutation. These findings point to a bipolar translocation model for RecBCD in which the two DNA helicases are complementary, travelling with opposite polarities, but in the same direction, on each strand of the antiparallel DNA duplex. This bipolar motor organization helps to explain various biochemical properties of RecBCD, notably its exceptionally high speed and processivity, and offers a mechanistic insight into aspects of RecBCD function.

Escherichia coli - enzymology

DNA, Single-Stranded - metabolism

Adenosine Triphosphatases - metabolism

Exodeoxyribonuclease V

Plasmids - metabolism

DNA, Single-Stranded - chemistry

Protein Subunits - metabolism

DNA, Single-Stranded - genetics

DNA Helicases - metabolism

Escherichia coli Proteins

Holoenzymes - metabolism

Models, Biological

Adenosine Triphosphate - metabolism

Base Sequence

Exodeoxyribonucleases - metabolism

Plasmids - chemistry

Plasmids - genetics

Kinetics

Details

Title: Subtitle: RecBCD enzyme is a bipolar DNA helicase
Creators: Mark S Dillingham - Section of Microbiology, Center for Genetics and Development, University of California, Davis, California 95616, USA
Maria Spies
Stephen C Kowalczykowski
Resource Type: Journal article
Publication Details: Nature (London), Vol.423(6942), pp.893-897
Publisher: England
DOI: 10.1038/nature01673
PMID: 12815438
ISSN: 0028-0836
eISSN: 1476-4687
Language: English
Date published: 06/19/2003
Academic Unit: Radiation Oncology; Biochemistry and Molecular Biology
Record Identifier: 9984024555002771

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