MutT homologue 1 (MTH1) removes N6-methyl-dATP from the dNTP pool

Research output: Contribution to journalArticle

Abstract

MutT homologue 1 (MTH1) removes oxidized nucleotides from the nucleotide pool and thereby prevents their incorporation into the genome and thereby reduces genotoxicity. We previously reported that MTH1 is an efficient catalyst of O6-methyl-dGTP hydrolysis suggesting that MTH1 may also sanitize the nucleotide pool from other methylated nucleotides. We here show that MTH1 efficiently catalyzes the hydrolysis of N6-methyl-dATP to N6-methyl-dAMP and further report that N6-methylation of dATP drastically increases the MTH1 activity. We also observed MTH1 activity with N6-methyl-ATP, albeit at a lower level. We show that N6-methyl-dATP is incorporated into DNA in vivo, as indicated by increased N6-methyl-dA DNA levels in embryos developed from MTH1 knock-out zebrafish eggs microinjected with N6-methyl-dATP compared with noninjected embryos. N6-methyl-dATP activity is present in MTH1 homologues from distantly related vertebrates, suggesting evolutionary conservation and indicating that this activity is important. Of note, N6-methyl-dATP activity is unique to MTH1 among related NUDIX hydrolases. Moreover, we present the structure of N6-methyl-dAMP-bound human MTH1, revealing that the N6-methyl group is accommodated within a hydrophobic active-site sub-pocket explaining why N6-methyl-dATP is a good MTH1 substrate. N6-methylation of DNA and RNA has been reported to have epigenetic roles and to affect mRNA metabolism. We propose that MTH1 acts in concert with adenosine deaminase-like protein isoform 1 (ADAL1) to prevent incorporation of N6-methyl-(d)ATP into DNA and RNA. This would hinder potential dysregulation of epigenetic control and RNA metabolism via conversion of N6-methyl-(d)ATP to N6-methyl-(d)AMP, followed by ADAL1 catalyzed deamination producing (d)IMP that can enter the nucleotide salvage pathway.

Details

Authors
Organisations
External organisations
  • Stockholm University
  • Karolinska Institutet
  • LIME, Karolinska institutet
  • Norwegian University of Science and Technology
  • Karolinska University Hospital
  • St. Olav’s University Hospital
  • University of Sheffield
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biochemistry and Molecular Biology
  • Medical Biotechnology
Original languageEnglish
Pages (from-to)4761-4772
JournalJournal of Biological Chemistry
Volume295
Issue number15
Publication statusPublished - 2020
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

Published under license by The American Society for Biochemistry and Molecular Biology, Inc.