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J. Biol. Chem., Vol. 275, Issue 39, 30186-30195, September 29, 2000
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and
From the Department of Molecular and Medical Genetics, University
of Toronto, Toronto M5S 1A8, Canada
The Cre recombinase is a member of the integrase
family of conservative site-specific recombinases. These proteins share
five conserved catalytic residues, one of which is a tyrosine that acts
as the nucleophile to attack the scissile phosphodiester bond in the
DNA target. Recombination by the Cre recombinase takes place in a
supramolecular structure called a synapse that consists of four
molecules of Cre bound to two DNA target sequences called lox sites. The synapse is held together by an intricate
network of protein-protein interactions. They bend the two sites into square planar structure that resembles a Holliday intermediate. We have
studied three mutant Cre proteins that appear to have defects in
synapsis (Cre A36V, Cre T41F, and Cre G314R). We found that they were
unable to carry out strand cleavage but that cleavage occurred if they
were mixed with a cleavage-defective Cre protein that lacks the
catalytic nucleophilic tyrosine residue. The three variant proteins
could also be complemented for the formation of a novel structure
("complexV"), which may be a cleaved synaptic intermediate. We
suggest that these three mutant proteins have a defect in DNA bending
and discuss the relationship between bending, synapsis, and cleavage.
Supported by a University of Toronto Open Scholarship.
§
To whom correspondence should be addressed: Dept. of Molecular and
Medical Genetics, Medical Sciences Bldg., University of Toronto,
Toronto M5S 1A8, Canada. Tel.: 416-978-6061; Fax: 416-978-6885; E-mail:
p.sadowski@utoronto.ca.
This article has been cited by other articles:
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V. Petyuk, J. McDermott, M. Cook, and B. Sauer Functional Mapping of Cre Recombinase by Pentapeptide Insertional Mutagenesis J. Biol. Chem., August 27, 2004; 279(35): 37040 - 37048. [Abstract] [Full Text] [PDF] |
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L. Lee and P. D. Sadowski Identification of Cre Residues Involved in Synapsis, Isomerization, and Catalysis J. Biol. Chem., September 19, 2003; 278(38): 36905 - 36915. [Abstract] [Full Text] [PDF] |
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L. Lee, L. C. H. Chu, and P. D. Sadowski Cre Induces an Asymmetric DNA Bend in Its Target loxP Site J. Biol. Chem., June 13, 2003; 278(25): 23118 - 23129. [Abstract] [Full Text] [PDF] |
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