3nhg

RB69 DNA Polymerase (S565G/Y567A) Ternary Complex with dTTP Opposite dG

spinqualitylabelsall models 3nhg, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3nhg is a 3 chain structure with sequence from Escherichia phage RB69. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.5Å Ligands: CA, DOC, TTP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function DPOL_BPR69 This polymerase possesses two enzymatic activities: DNA synthesis (polymerase) and an exonucleolytic activity that degrades single stranded DNA in the 3'- to 5'-direction. Publication Abstract from PubMed We have previously observed that stepwise replacement of amino acid residues in the nascent base-pair binding pocket of RB69 DNA polymerase (RB69pol) with Ala or Gly expanded the space in this pocket, resulting in a progressive increase in misincorporation. However, in vivo results with similar RB69pol nascent base-pair binding pocket mutants showed that mutation rates, as determined by the T4 phage rI forward assay and rII reversion assay, were significantly lower for the RB69pol S565G/Y567A double mutant than for the Y567A single mutant, the opposite of what we would have predicted. To investigate the reasons for this unexpected result, we have determined the pre-steady-state kinetic parameters and crystal structures of relevant ternary complexes. We found that the S565G/Y567A mutant generally had greater base selectivity than the Y567A mutant and that the kinetic parameters for dNMP insertion, excision of the 3'-terminal nucleotide residue, and primer extension beyond a mispair differed not only between these two mutants but also between the two highly mutable sequences in the T4 rI complementary strand. Comparison of the crystal structures of these two mutants with correct and incorrect incoming dNTPs provides insight into the unexpected increase in the fidelity of the S565G/Y567A double mutant. Taken together, the kinetic and structural results provide a basis for integrating and interpreting in vivo and in vitro observations. Variation in Mutation Rates Caused by RB69pol Fidelity Mutants Can Be Rationalized on the Basis of Their Kinetic Behavior and Crystal Structures.,Xia S, Wang M, Lee HR, Sinha A, Blaha G, Christian T, Wang J, Konigsberg W J Mol Biol. 2011 Jan 7. PMID:21216248 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also DNA polymerase 3D structures

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