1ght
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SOLUTION STRUCTURE OF THE CATALYTIC DOMAIN OF GAMMA DELTA RESOLVASE
OverviewOverview
The site-specific DNA recombinase, gammadelta resolvase, from Escherichia, coli catalyzes recombination of res site-containing plasmid DNA to two, catenated circular DNA products. The catalytic domain (residues 1-105), lacking a C-terminal dimerization interface, has been constructed and the, NMR solution structure of the monomer determined. The RMSD of the NMR, conformers for residues 2-92 excluding residues 37-45 and 64-73 is 0.41 A, for backbone atoms and 0.88 A for all heavy atoms. The NMR solution, structure of the monomeric catalytic domain (residues 1-105) was found to, be formed by a four-stranded parallel beta-sheet surrounded by three, helices. The catalytic domain (residues 1-105), deficient in the, C-terminal dimerization domain, was monomeric at high salt concentration, but displayed unexpected dimerization at lower ionic strength. The unique, solution dimerization interface at low ionic strength was mapped by NMR., With respect to previous crystal structures of the dimeric catalytic, domain (residues 1-140), differences in the average conformation of, active-site residues were found at loop 1 containing the catalytic S10, nucleophile, the beta1 strand containing R8, and at loop 3 containing D67, R68 and R71, which are required for catalysis. The active-site loops, display high-frequency and conformational backbone dynamics and are less, well defined than the secondary structures. In the solution structure, the, D67 side-chain is proximal to the S10 side-chain making the D67, carboxylate group a candidate for activation of S10 through general base, catalysis. Four conserved Arg residues can function in the activation of, the phosphodiester for nucleophilic attack by the S10 hydroxyl group. A, mechanism for covalent catalysis by this class of recombinases is proposed, that may be related to dimer interface dissociation.
About this StructureAbout this Structure
1GHT is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Solution structure of the catalytic domain of gammadelta resolvase. Implications for the mechanism of catalysis., Pan B, Maciejewski MW, Marintchev A, Mullen GP, J Mol Biol. 2001 Jul 27;310(5):1089-107. PMID:11501998
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