Separation-of-function mutants unravel the dual-reaction mode of human 8-oxoguanine DNA glycosylase

Structure. 2011 Jan 12;19(1):117-27. doi: 10.1016/j.str.2010.09.023.

Abstract

7,8-Dihydro-8-oxoguanine (8oxoG) is a major mutagenic base lesion formed when reactive oxygen species react with guanine in DNA. The human 8oxoG DNA glycosylase (hOgg1) recognizes and initiates repair of 8oxoG. hOgg1 is acknowledged as a bifunctional DNA glycosylase catalyzing removal of the damaged base followed by cleavage of the backbone of the intermediate abasic DNA (AP lyase/β-elimination). When acting on 8oxoG-containing DNA, these two steps in the hOgg1 catalysis are considered coupled, with Lys249 implicated as a key residue. However, several lines of evidence point to a concurrent and independent monofunctional hydrolysis of the N-glycosylic bond being the in vivo relevant reaction mode of hOgg1. Here, we present biochemical and structural evidence for the monofunctional mode of hOgg1 by design of separation-of-function mutants. Asp268 is identified as the catalytic residue, while Lys249 appears critical for the specific recognition and final alignment of 8oxoG during the hydrolysis reaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8-Hydroxy-2'-Deoxyguanosine
  • Aspartic Acid / chemistry
  • Binding Sites
  • Catalytic Domain
  • Crystallography, X-Ray
  • DNA Cleavage
  • DNA Glycosylases / chemistry*
  • DNA Glycosylases / genetics
  • Deoxyguanosine / analogs & derivatives
  • Deoxyguanosine / chemistry
  • Humans
  • Hydrolysis
  • Kinetics
  • Lyases / chemistry
  • Polynucleotides / chemistry*
  • Protein Binding
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / genetics

Substances

  • Polynucleotides
  • Recombinant Fusion Proteins
  • Aspartic Acid
  • 8-Hydroxy-2'-Deoxyguanosine
  • DNA Glycosylases
  • oxoguanine glycosylase 1, human
  • Lyases
  • Deoxyguanosine

Associated data

  • PDB/2XHI