2bpg
STRUCTURES OF TERNARY COMPLEXES OF RAT DNA POLYMERASE BETA, A DNA TEMPLATE-PRIMER, AND DDCTPSTRUCTURES OF TERNARY COMPLEXES OF RAT DNA POLYMERASE BETA, A DNA TEMPLATE-PRIMER, AND DDCTP
Structural highlights
Function[DPOLB_RAT] Repair polymerase that plays a key role in base-excision repair. Has 5'-deoxyribose-5-phosphate lyase (dRP lyase) activity that removes the 5' sugar phosphate and also acts as a DNA polymerase that adds one nucleotide to the 3' end of the arising single-nucleotide gap. Conducts 'gap-filling' DNA synthesis in a stepwise distributive fashion rather than in a processive fashion as for other DNA polymerases. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTwo ternary complexes of rat DNA polymerase beta (pol beta), a DNA template-primer, and dideoxycytidine triphosphate (ddCTP) have been determined at 2.9 A and 3.6 A resolution, respectively. ddCTP is the triphosphate of dideoxycytidine (ddC), a nucleoside analog that targets the reverse transcriptase of human immunodeficiency virus (HIV) and is at present used to treat AIDS. Although crystals of the two complexes belong to different space groups, the structures are similar, suggesting that the polymerase-DNA-ddCTP interactions are not affected by crystal packing forces. In the pol beta active site, the attacking 3'-OH of the elongating primer, the ddCTP phosphates, and two Mg2+ ions are all clustered around Asp190, Asp192, and Asp256. Two of these residues, Asp190 and Asp256, are present in the amino acid sequences of all polymerases so far studied and are also spatially similar in the four polymerases--the Klenow fragment of Escherichia coli DNA polymerase I, HIV-1 reverse transcriptase, T7 RNA polymerase, and rat DNA pol beta--whose crystal structures are now known. A two-metal ion mechanism is described for the nucleotidyl transfer reaction and may apply to all polymerases. In the ternary complex structures analyzed, pol beta binds to the DNA template-primer in a different manner from that recently proposed for other polymerase-DNA models. Structures of ternary complexes of rat DNA polymerase beta, a DNA template-primer, and ddCTP.,Pelletier H, Sawaya MR, Kumar A, Wilson SH, Kraut J Science. 1994 Jun 24;264(5167):1891-903. PMID:7516580[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References |
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