Xer site-specific recombination. DNA strand rejoining by recombinase XerC.
Xer site-specific recombination functions in the stable maintenance of circular replicons in Escherichia coli. Each of two related recombinase proteins, XerC and XerD, cleaves a specific pair of DNA strands, exchanges them, and rejoins them to the partner DNA molecule during a complete recombination reaction. The rejoining activity of recombinase XerC has been analyzed using isolated covalent XerC-DNA complexes resulting from DNA cleavage reactions upon Holliday junction substrates. These covalent protein-DNA complexes are competent in the rejoining reaction, demonstrating that covalently bound XerC can catalyze strand rejoining in the absence of other proteins. This contrasts with a recombinase-mediated cleavage reaction, which requires the presence of both recombinases, the recombinase mediating catalysis at any given time requiring activation by the partner recombinase. In a recombining nucleoprotein complex, both cleavage and rejoining can occur prior to dissociation of the complex.
Division of Molecular Genetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
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Grainge
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Sherratt
D001483:Base Sequence; D004254:DNA Nucleotidyltransferases / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D019426:Integrases; D008969:Molecular Sequence Data; D045522:Recombinases; D011995:Recombination, Genetic
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D045522:Recombinases; C473360:XerC protein, E coli; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C473361:XerD protein, E coli; C115006:integron integrase IntI1