The domains of mammalian base excision repair enzyme N-methylpurine-DNA glycosylase. Interaction, conformational change, and role in DNA binding and damage recognition

Rabindra Roy, Amalendra Kumar, J. Ching Lee, Sankar Mitra

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20 Scopus citations


Repair of a variety of alkylated base adducts in DNA is initiated by their removal by N-methylpurine-DNA glycosylase. The 31-kDa mouse N- methylpurine-DNA glycosylase, derived by deletion of 48 amino acid residues from the 333-residue wild type protein without loss of activity, was analyzed for the presence of protease-resistant domains with specific roles in substrate binding and catalysis. Increasing proteolysis with trypsin generated first a 29-kDa polypeptide by removal of 42 amino-terminal residues, followed by production of 8-, 6-, and 13-kDa fragments with defined, nonoverlapping boundaries. The 8- and 13-kDa domains include the amino and carboxyl termini, respectively. Based on DNA-affinity chromatography and the protease protection assay, it appears that the 6- and 13-kDa domains are necessary for nontarget DNA binding and that the 8-kDa domain, in cooperation with the other two domains, participates in recognition of damaged bases. Furthermore, chemical cross-linking studies indicated that, in the presence of substrate DNA, the 8- and 6-kDa domains undergo conformational changes reflected by both protection from proteolysis and reduced availability of cysteine residues for the thiol-exchange reaction.

Original languageEnglish (US)
Pages (from-to)23690-23697
Number of pages8
JournalJournal of Biological Chemistry
Issue number39
StatePublished - Oct 10 1996


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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