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Publication Detail

Title: The DNA damage-sensing NER repair factor XPC-RAD23B does not recognize bulky DNA lesions with a missing nucleotide opposite the lesion.

Authors: Feher, Katie M; Kolbanovskiy, Alexander; Durandin, Alexander; Shim, Yoonjung; Min, Jung-Hyun; Lee, Yuan Cho; Shafirovich, Vladimir; Mu, Hong; Broyde, Suse; Geacintov, Nicholas E

Published In DNA Repair (Amst), (2020 12)

Abstract: The Nucleotide Excision Repair (NER) mechanism removes a wide spectrum of structurally different lesions that critically depend on the binding of the DNA damage sensing NER factor XPC-RAD23B (XPC) to the lesions. The bulky mutagenic benzo[a]pyrene diol epoxide metabolite-derived cis- and trans-B[a]P-dG lesions (G*) adopt base-displaced intercalative (cis) or minor groove (trans) conformations in fully paired DNA duplexes with the canonical C opposite G* (G*:C duplexes). While XPC has a high affinity for binding to these DNA lesions in fully complementary double-stranded DNA, we show here that deleting only the C in the complementary strand opposite the lesion G* embedded in 50-mer duplexes, fully abrogates XPC binding. Accurate values of XPC dissociation constants (KD) were determined by employing an excess of unmodified DNA as a competitor; this approach eliminated the binding and accumulation of multiple XPC molecules to the same DNA duplexes, a phenomenon that prevented the accurate estimation of XPC binding affinities in previous studies. Surprisingly, a detailed comparison of XPC dissociation constants KD of unmodified and lesion-containing G*:Del complexes, showed that the KD values were -2.5-3.6 times greater in the case of G*:Del than in the unmodified G:Del and fully base-paired G:C duplexes. The origins of this unexpected XPC lesion avoidance effect is attributed to the intercalation of the bulky, planar B[a]P aromatic ring system between adjacent DNA bases that thermodynamically stabilize the G*:Del duplexes. The strong lesion-base stacking interactions associated with the absence of the partner base, prevent the DNA structural distortions needed for the binding of the BHD2 and BHD3 β-hairpins of XPC to the deletion duplexes, thus accounting for the loss of XPC binding and the known NER-resistance of G*:Del duplexes.

PubMed ID: 33035795 Exiting the NIEHS site

MeSH Terms: 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/chemistry; 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/metabolism*; DNA Adducts/chemistry; DNA Adducts/metabolism*; DNA Repair Enzymes/metabolism; DNA Repair*; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/metabolism*; DNA/chemistry; DNA/metabolism; Humans; Kinetics; Molecular Dynamics Simulation; Nucleic Acid Conformation; Protein Conformation; Saccharomyces cerevisiae Proteins/chemistry; Saccharomyces cerevisiae Proteins/metabolism*; Saccharomyces cerevisiae/enzymology; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae/metabolism; Substrate Specificity

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