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| {{STRUCTURE_2uvv| PDB=2uvv | SCENE= }} | | {{STRUCTURE_2uvv| PDB=2uvv | SCENE= }} |
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| '''CRYSTAL STRUCTURES OF MUTANT DPO4 DNA POLYMERASES WITH 8-OXOG CONTAINING DNA TEMPLATE-PRIMER CONSTRUCTS'''
| | ===CRYSTAL STRUCTURES OF MUTANT DPO4 DNA POLYMERASES WITH 8-OXOG CONTAINING DNA TEMPLATE-PRIMER CONSTRUCTS=== |
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| ==Overview==
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| Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4) has been shown to catalyze bypass of 7,8-dihydro-8-oxodeoxyguanosine (8-oxoG) in a highly efficient and relatively accurate manner. Crystal structures have revealed a potential role for Arg(332) in stabilizing the anti conformation of the 8-oxoG template base by means of a hydrogen bond or ion-dipole pair, which results in an increased enzymatic efficiency for dCTP insertion and makes formation of a Hoogsteen pair between 8-oxoG and dATP less favorable. Site-directed mutagenesis was used to replace Arg(332) with Ala, Glu, Leu, or His in order to probe the importance of Arg(332) in accurate and efficient bypass of 8-oxoG. The double mutant Ala(331)Ala(332) was also prepared to address the contribution of Arg(331). Transientstate kinetic results suggest that Glu(332) retains fidelity against bypass of 8-oxoG that is similar to wild type Dpo4, a result that was confirmed by tandem mass spectrometric analysis of full-length extension products. A crystal structure of the Dpo4 Glu(332) mutant and 8-oxoG:C pair revealed water-mediated hydrogen bonds between Glu(332) and the O-8 atom of 8-oxoG. The space normally occupied by Arg(332) side chain is empty in the crystal structures of the Ala(332) mutant. Two other crystal structures show that a Hoogsteen base pair is formed between 8-oxoG and A in the active site of both Glu(332) and Ala(332) mutants. These results support the view that a bond between Arg(332) and 8-oxoG plays a role in determining the fidelity and efficiency of Dpo4-catalyzed bypass of the lesion.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17468100}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17468100 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17468100}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Transferase]] | | [[Category: Transferase]] |
| [[Category: Translesion dna polymerase]] | | [[Category: Translesion dna polymerase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 17:36:41 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 17:12:20 2008'' |
