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Crystal structure of human NEIL1 (P2G (242K) C(delta)100) glycosylase bound to DNA duplex containing urea
Structural highlights
FunctionNEIL1_HUMAN 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, formamidopyrimidine (Fapy) and 5-hydroxyuracil. Has marginal activity towards 8-oxoguanine. 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. Has DNA glycosylase/lyase activity towards mismatched uracil and thymine, in particular in U:C and T:C mismatches.[1] [2] [3] [4] Publication Abstract from PubMedThe N-(2-deoxy-d-erythro-pentofuranosyl)-urea DNA lesion forms following hydrolytic fragmentation of cis-5R,6S- and trans-5R,6R-dihydroxy-5,6-dihydrothymidine (thymine glycol, Tg) or from oxidation of 7,8-dihydro-8-oxo-deoxyguanosine (8-oxodG) and subsequent hydrolysis. It interconverts between alpha and beta deoxyribose anomers. Synthetic oligodeoxynucleotides containing this adduct are efficiently incised by unedited (K242) and edited (R242) forms of the hNEIL1 glycosylase. The structure of a complex between the active site unedited mutant CDelta100 P2G hNEIL1 (K242) glycosylase and double-stranded (ds) DNA containing a urea lesion reveals a pre-cleavage intermediate, in which the Gly2 N-terminal amine forms a conjugate with the deoxyribose C1' of the lesion, with the urea moiety remaining intact. This structure supports a proposed catalytic mechanism in which Glu3-mediated protonation of O4' facilitates attack at deoxyribose C1'. The deoxyribose is in the ring-opened configuration with the O4' oxygen protonated. The electron density of Lys242 suggests the 'residue 242-in conformation' associated with catalysis. This complex likely arises because the proton transfer steps involving Glu6 and Lys242 are hindered due to Glu6-mediated H-bonding with the Gly2 and the urea lesion. Consistent with crystallographic data, biochemical analyses show that the CDelta100 P2G hNEIL1 (K242) glycosylase exhibits a residual activity against urea-containing dsDNA. Base excision repair of the N-(2-deoxy-d-erythro-pentofuranosyl)-urea lesion by the hNEIL1 glycosylase.,Tomar R, Minko IG, Sharma P, Kellum AH, Lei L, Harp JM, Iverson TM, Lloyd RS, Egli M, Stone MP Nucleic Acids Res. 2023 May 8;51(8):3754-3769. doi: 10.1093/nar/gkad164. PMID:37014002[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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