AlkA protein is the third Escherichia coli DNA repair protein excising a ring fragmentation product of thymine

C. V. Privezentzev, M. Saparbaev, A. Sambandam, M. M. Greenberg, J. Laval

Research output: Contribution to journalArticlepeer-review

Abstract

Various forms of oxidative stress lead to the formation of damaged bases including N-(2-deoxy-β-D-erythro-pentofuranosyl)-N-3-(2R-hydroxyisobutyric acid)-urea or αRT, the fragmentation product of thymine formed from 5R-thymidine C5-hydrate upon hydrolysis. It was shown that αRT is excised by Escherichia coli Fpg and Nth proteins. Here we report that when present in DNA, αRT is, in addition, a substrate for the E. coli AlkA protein with an apparent K(m) value of ≃170 nM. αRT positioned opposite T, dG, dC, and dA were efficiently excised by AlkA protein from duplex oligodeoxynucleotides in the following order: dA ≃ T >> dC ≃ dG. This is the first example of the excision of a ring opened form of a pyrimidine by AlkA protein and also the first example where the same DNA base lesion is excised by three different DNA glycosylases of the base excision repair pathway. The present results suggest possible structural similarity of the active site between E. coli AlkA, Fpg, and Nth proteins.

Original languageEnglish (US)
Pages (from-to)14263-14268
Number of pages6
JournalBiochemistry
Volume39
Issue number46
DOIs
StatePublished - Nov 21 2000
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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