The C-terminal domain of the adenine-DNA glycosylase MutY confers specificity for 8-oxoguanine.adenine mispairs and may have evolved from MutT, an 8-oxo-dGTPase.

Published

Journal Article

MutY is an adenine-DNA glycosylase with specificity for mismatches involving 8-oxoguanine (oG.A) or guanine (G.A). In addition to a 25 kDa catalytic domain common to all members of its DNA glycosylase superfamily, MutY has a 14 kDa C-terminal domain. Sequence analyses suggest that this C-terminal domain is distantly related to MutT, a pyrophosphohydrolase specific for 2'-deoxy-8-oxoguanosine triphosphate (doGTP). Here we present biochemical evidence that the MutT-like domain of MutY is the principal determinant of oG specificity. First, MutY dissociates approximately 1500-fold more slowly from oG-containing product DNA than from G-containing product, but a truncated protein lacking the C-terminal domain dissociates as rapidly from oG-DNA as the full-length protein dissociates from G-DNA. Second, MutY removes adenine from oG.A mismatches almost 30-fold faster than from G.A mismatches in a pre-steady-state assay, but deletion of the C-terminal domain reduces this specificity for oG.A to less than 4-fold. The kinetic data are consistent with a model in which binding of oG to the C-terminal domain of MutY accelerates the pre-steady-state glycosylase reaction by facilitating adenine base flipping. The observation that oG specificity derives almost exclusively from the C-terminal domain of MutY adds credence to the sequence analyses and suggests that specificity for oG.A mismatches was acquired by fusion of a MutT-like protein onto the core catalytic domain of an adenine-DNA glycosylase.

Full Text

Duke Authors

Cited Authors

  • Noll, DM; Gogos, A; Granek, JA; Clarke, ND

Published Date

  • May 18, 1999

Published In

Volume / Issue

  • 38 / 20

Start / End Page

  • 6374 - 6379

PubMed ID

  • 10350454

Pubmed Central ID

  • 10350454

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi990335x

Language

  • eng

Conference Location

  • United States