title: Structural Basis for Avoidance of Promutagenic DNA Repair by MutY Adenine DNA Glycosylase.
abstract: The highly mutagenic A:oxoG (8-oxoguanine) base pair in DNA most frequently arises by aberrant replication of the primary oxidative lesion C:oxoG. This lesion is particularly insidious because neither of its constituent nucleobases faithfully transmit genetic information from the original C:G base pair. Repair of A:oxoG is initiated by adenine DNA glycosylase, which catalyzes hydrolytic cleavage of the aberrant A nucleobase from the DNA backbone. These enzymes, MutY in bacteria and MUTYH in humans, scrupulously avoid processing of C:oxoG because cleavage of the C residue in C:oxoG would actually promote mutagenic conversion to A:oxoG. Here we analyze the structural basis for rejection of C:oxoG by MutY, using a synthetic crystallography approach to capture the enzyme in the process of inspecting the C:oxoG anti-substrate, with which it ordinarily binds only fleetingly. We find that MutY uses two distinct strategies to avoid presentation of C to the enzyme active site. Firstly, MutY possesses an exo-site that serves as a decoy for C, and secondly, repulsive forces with a key active site residue prevent stable insertion of C into the nucleobase recognition pocket within the enzyme active site.
authors.affiliation: From the Departments of Chemistry and Chemical Biology.
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.affiliation: From the Departments of Chemistry and Chemical Biology.
authors.forename: Seung-Joo
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: From the Departments of Chemistry and Chemical Biology, Stem Cell and Regenerative Biology, and Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138 gregory_verdine@harvard.edu.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Verdine
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004249:DNA Damage; D045647:DNA Glycosylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000502:physiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001411:Geobacillus stearothermophilus / Q000201:enzymology* / Q000235:genetics; D006147:Guanine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011994:Recombinant Proteins; C024829:8-hydroxyguanine; D006147:Guanine; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase
keywords: 8-oxoguanine (8-oxoG); DNA repair; DNA-protein interaction; base excision repair (BER); structural biology