3py8

Crystal structure of a mutant of the large fragment of DNA polymerase I from thermus aquaticus in a closed ternary complex with DNA and ddCTP

spinqualitylabelsall models 3py8, resolution 1.74Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3py8 is a 3 chain structure with sequence from Atcc 25104. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: DCT, GOL, MG, MN NonStd Res: DOC Gene: polA, pol1 (ATCC 25104) Activity: DNA-directed DNA polymerase, with EC number 2.7.7.7 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed DNA is being constantly damaged by endo- and exogenous agents such as reactive oxygen species, chemicals, radioactivity, and ultraviolet radiation. Additionally, DNA is inherently labile, and this can result in, for example, the spontaneous hydrolysis of the glycosidic bond that connects the sugar and the nucleobase moieties in DNA; this results in abasic sites. It has long been obscure how cells achieve DNA synthesis past these lesions, and only recently has it been discovered that several specialized DNA polymerases are involved in translesion synthesis. The underlying mechanisms that render one DNA polymerase competent in translesion synthesis while another DNA polymerase fails are still indistinct. Recently two variants of Taq DNA polymerase that exhibited higher lesion bypass ability than the wild-type enzyme were identified by directed-evolution approaches. Strikingly, in both approaches it was independently found that substitution of a single nonpolar amino acid side chain by a cationic side chain increases the capability of translesion synthesis. Here, we combined both mutations in a single enzyme. We found that the KlenTaq DNA polymerase that bore both mutations superseded the wild-type as well as the respective single mutants in translesion-bypass proficiency. Further insights in the molecular basis of the detected gain of translesion-synthesis function were obtained by structural studies of DNA polymerase variants caught in processing canonical and damaged substrates. We found that increased positive charge of the surface potential in the area proximal to the negatively charged substrates promotes translesion synthesis by KlenTaq DNA polymerase, an enzyme that has very limited naturally evolved capability to perform translesion synthesis. Since expanded positively charged surface potential areas are also found in naturally evolved translesion DNA polymerases, our results underscore the impact of charge on the proficiency of naturally evolved translesion DNA polymerases. Learning from Directed Evolution: Thermus aquaticus DNA Polymerase Mutants with Translesion Synthesis Activity.,Obeid S, Schnur A, Gloeckner C, Blatter N, Welte W, Diederichs K, Marx A Chembiochem. 2011 Apr 8. doi: 10.1002/cbic.201000783. PMID:21480455 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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