Structure of human MTH1, a nudix family hydrolase that selectively degrades oxidized purine nucleoside triphosphates

Masaki Mishima, Yasunari Sakai, Noriyuki Itoh, Hiroyuki Kamiya, Masato Furuichi, Masayuki Takahashi, Yuriko Yamagata, Shigenori Iwai, Yusaku Nakabeppu, Masahiro Shirakawa

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

Oxygen radicals generated through normal cellular respiration processes can cause mutations in genomic and mitochondrial DNA. Human MTH1 hydrolyzes oxidized purine nucleoside triphosphates, such as 8-oxo-dGTP and 2-hydroxy-dATP, to monophosphates, thereby preventing the misincorporation of these oxidized nucleotides during replication. Here we present the solution structure of MTH1 solved by multidimensional heteronuclear NMR spectroscopy. The protein adopts a fold similar to that of Escherichia coli MutT, despite the low sequence similarity between these proteins outside the conserved Nudix motif. The substrate-binding pocket of MTH1, deduced from chemical shift perturbation experiments, is located at essentially the same position as in MutT; however, a pocket-forming helix is largely displaced in MTH1 (∼9 Å) such that the shape of the pocket differs between the two proteins. Detailed analysis of the pocket-forming residues enabled us to identify Asn33 as one of the key residues in MTH1 for discriminating the oxidized form of purine, and mutation of this residue modifies the substrate specificity. We also show that MTH1 catalyzes hydrolysis of 8-oxo-dGTP through nucleophilic substitution of water at the β-phosphate.

Original languageEnglish
Pages (from-to)33806-33815
Number of pages10
JournalJournal of Biological Chemistry
Volume279
Issue number32
DOIs
Publication statusPublished - Aug 6 2004

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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