Crystal structure of the DNA repair enzyme endonuclease-VIII (Nei) from E. coli: The R252A mutant at 2.05 resolution.
[END8_ECOLI] Involved in base excision repair of DNA damaged by oxidation or by mutagenic agents. Acts as DNA glycosylase that recognizes and removes damaged bases. Has a preference for oxidized pyrimidines, such as thymine glycol, 5,6-dihydrouracil and 5,6-dihydrothymine. Acts on DNA bubble and 3'-fork structures, suggesting a role in replication-associated DNA repair. Has AP (apurinic/apyrimidinic) lyase activity and introduces nicks in the DNA strand. Cleaves the DNA backbone by beta-delta elimination to generate a single-strand break at the site of the removed base with both 3'- and 5'-phosphates.
Publication Abstract from PubMed
Escherichia coli endonuclease VIII (Nei) excises oxidized pyrimidines from DNA. It shares significant sequence homology and similar mechanism with Fpg, a bacterial 8-oxoguanine glycosylase. The structure of a covalent Nei-DNA complex has been recently determined, revealing critical amino acid residues which are important for DNA binding and catalysis. Several Fpg structures have also been reported; however, analysis of structural dynamics of Fpg/Nei family proteins has been hindered by the lack of structures of uncomplexed and DNA-bound enzymes from the same source. We report a 2.8 A resolution structure of free wild-type Nei and two structures of its inactive mutants, Nei-E2A (2.3 A) and Nei-R252A (2.05 A). All three structures are virtually identical, demonstrating that the mutations did not affect the overall conformation of the protein in its free state. The structures show a significant conformational change compared with the Nei structure in its complex with DNA, reflecting a approximately 50 degrees rotation of the two main domains of the enzyme. Such interdomain flexibility has not been reported previously for any DNA glycosylase and may present the first evidence for a global DNA-induced conformational change in this class of enzymes. Several local but functionally relevant structural changes are also evident in other parts of the enzyme.
Structure of the uncomplexed DNA repair enzyme endonuclease VIII indicates significant interdomain flexibility.,Golan G, Zharkov DO, Feinberg H, Fernandes AS, Zaika EI, Kycia JH, Grollman AP, Shoham G Nucleic Acids Res. 2005 Sep 6;33(15):5006-16. Print 2005. PMID:16145054
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.