1u94
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Crystal Structure of E. Coli RecA in a Compressed Helical Filament Form 2
OverviewOverview
The X-ray crystal structure of uncomplexed Escherichia coli RecA protein, has been determined in three new crystal forms at resolutions of 1.9 A, 2.0 A, and 2.6 A. The RecA protein used for this study contains the extra, residues Gly-Ser-His-Met at the N terminus, but retains normal, ssDNA-dependent ATPase and coprotease activities. In all three crystals, RecA is packed in a right-handed helical filament with a pitch of, approximately 74 A. These RecA filaments are compressed relative to the, original crystal structure of RecA, which has a helical pitch of 82.7 A., In the structures of the compressed RecA filament, the monomer-monomer, interface and the core domain are essentially the same as in the RecA, structure with the 83 A pitch. The change in helical pitch is accommodated, by a small movement of the N-terminal domain, which is reoriented to, preserve the contacts it makes at the monomer-monomer interface. The new, crystal structures show significant variation in the orientation and, conformation of the C-terminal domain, as well as in the inter-filament, packing interactions. In crystal form 2, a calcium ion is bound closely to, a beta-hairpin of the C-terminal domain and to Asp38 of a neighboring, filament, and residues 329-331 of the C-terminal tail become ordered to, contact a neighboring filament. In crystal forms 3 and 4, a sulfate ion or, a phosphate anion is bound to the same site on RecA as the beta-phosphate, group of ADP, causing an opening of the P-loop. Altogether, the structures, show the conformational variability of RecA protein in the crystalline, state, providing insight into many aspects of RecA function.
About this StructureAbout this Structure
1U94 is a Single protein structure of sequence from Escherichia coli with CA as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of Escherichia coli RecA in a compressed helical filament., Xing X, Bell CE, J Mol Biol. 2004 Oct 1;342(5):1471-85. PMID:15364575
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