1f44
From Proteopedia
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CRYSTAL STRUCTURE OF TRIMERIC CRE RECOMBINASE-LOX COMPLEX
Overview
The crystal structure of a novel Cre-Lox synapse was solved using phases, from multiple isomorphous replacement and anomalous scattering, and, refined to 2.05 A resolution. In this complex, a symmetric protein trimer, is bound to a Y-shaped three-way DNA junction, a marked departure from the, pseudo-4-fold symmetrical tetramer associated with Cre-mediated LoxP, recombination. The three-way DNA junction was accommodated by a simple, kink without significant distortion of the adjoining DNA duplexes., Although the mean angle between DNA arms in the Y and X structures was, similar, adjacent Cre trimer subunits rotated 29 degrees relative to those, in the tetramers. This rotation was accommodated at the protein-protein, and DNA-DNA interfaces by interactions that are "quasi-equivalent" to, those in the tetramer, analogous to packing differences of chemically, identical viral subunits at non-equivalent positions in icosahedral, capsids. This structural quasi-equivalence extends to function as Cre can, bind to, cleave and perform strand transfer with a three-way Lox, substrate. The structure explains the dual recognition of three and, four-way junctions by site-specific recombinases as being due to shared, structural features between the differently branched substrates and, plasticity of the protein-protein interfaces. To our knowledge, this is, the first direct demonstration of quasi-equivalence in both the assembly, and function of an oligomeric enzyme.
About this Structure
1F44 is a Single protein structure of sequence from Enterobacteria phage p21. Full crystallographic information is available from OCA.
Reference
Quasi-equivalence in site-specific recombinase structure and function: crystal structure and activity of trimeric Cre recombinase bound to a three-way Lox DNA junction., Woods KC, Martin SS, Chu VC, Baldwin EP, J Mol Biol. 2001 Oct 12;313(1):49-69. PMID:11601846
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