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Oxanine DNA glycosylase activities in mammalian systems

Liang Dong1, Lisiane B Meira, Tapas K Hazra

  • 1Department of Genetics and Biochemistry, South Carolina Experiment Station, Clemson University, Room 219, Biosystems Research Complex, 51 New Cherry Street, Clemson, SC 29634, United States.

DNA Repair
|October 24, 2007
PubMed

Insights

Oxanine, a cytotoxic DNA lesion from guanine deamination, is repaired by oxanine DNA glycosylase (ODG) enzymes. Research identified additional ODG activities in mammalian tissues beyond the known murine alkyladenine glycosylase (Aag).

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Genetics

Background:

  • DNA bases like adenine, guanine, and cytosine can undergo deamination under nitrosative stress.
  • Oxanine, a guanine deamination product, is a cytotoxic and potentially mutagenic DNA lesion.
  • Enzymatic repair mechanisms for oxanine are not well-studied.

Purpose of the Study:

  • To investigate additional oxanine DNA glycosylase (ODG) activities in mammalian tissues.
  • To characterize the ODG activities of known human DNA glycosylases.

Main Methods:

  • Analysis of partially purified proteins from mammalian cell extracts.
  • Oxanine DNA cleavage assays using purified human glycosylases (hAAG, hNEIL1, hSMUG1).

Main Results:

  • Additional ODG activities were detected in Aag knockout mouse tissues and other mammalian tissues.
  • Partially purified proteins indicated the presence of ODG enzymes beyond Aag.
  • Human glycosylases hNEIL1 and hSMUG1 showed weak but detectable ODG activities.
  • hAAG exhibited the highest ODG activity, while hSMUG1 had the lowest.

Conclusions:

  • Mammalian tissues possess ODG enzymes beyond Aag.
  • hNEIL1 and hSMUG1 possess weak oxanine DNA glycosylase activity.
  • hAAG is a significant ODG enzyme in human cells.

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