SNAP output for PDB entry 2uvw [SNAP web server]

PDB-id

2uvw; SNAP-derived features in text and JSON formats; DNAproDB

Class

transferase

Method

X-ray (2.09 Å)

Summary

Crystal structures of mutant dpo4 DNA polymerases with 8-oxog containing DNA template-primer constructs

Reference

Eoff RL, Irimia A, Angel KC, Egli M, Guengerich FP (2007): "Hydrogen Bonding of 7,8-Dihydro-8-Oxodeoxyguanosine with a Charged Residue in the Little Finger Domain Determines Miscoding Events in Sulfolobus Solfataricus DNA Polymerase Dpo4." J.Biol.Chem., 282, 19831. doi: 10.1074/JBC.M702290200.

Abstract

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.