title: Structural basis for the suppression of skin cancers by DNA polymerase eta.
abstract: DNA polymerase eta (Poleta) is unique among eukaryotic polymerases in its proficient ability for error-free replication through ultraviolet-induced cyclobutane pyrimidine dimers, and inactivation of Poleta (also known as POLH) in humans causes the variant form of xeroderma pigmentosum (XPV). We present the crystal structures of Saccharomyces cerevisiae Poleta (also known as RAD30) in ternary complex with a cis-syn thymine-thymine (T-T) dimer and with undamaged DNA. The structures reveal that the ability of Poleta to replicate efficiently through the ultraviolet-induced lesion derives from a simple and yet elegant mechanism, wherein the two Ts of the T-T dimer are accommodated in an active site cleft that is much more open than in other polymerases. We also show by structural, biochemical and genetic analysis that the two Ts are maintained in a stable configuration in the active site via interactions with Gln 55, Arg 73 and Met 74. Together, these features define the basis for Poleta's action on ultraviolet-damaged DNA that is crucial in suppressing the mutagenic and carcinogenic consequences of sun exposure, thereby reducing the incidence of skin cancers in humans.
authors.affiliation: Department of Structural and Chemical Biology, Mount Sinai School of Medicine, Box 1677, 1425 Madison Avenue, New York, New York 10029, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Silverstein
authors.forename: Robert E
authors.initials: RE
authors.lastname: Johnson
authors.forename: Rinku
authors.initials: R
authors.lastname: Jain
authors.forename: Louise
authors.initials: L
authors.lastname: Prakash
authors.forename: Satya
authors.initials: S
authors.lastname: Prakash
authors.forename: Aneel K
authors.initials: AK
authors.lastname: Aggarwal
mesh_terms: D055162:Biocatalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D020125:Mutation, Missense; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D011740:Pyrimidine Dimers / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D012878:Skin Neoplasms / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship; D014983:Xeroderma Pigmentosum / Q000201:enzymology / Q000235:genetics; D000099270:Y-Family DNA Polymerases
chemical_list: D004247:DNA; D004259:DNA-Directed DNA Polymerase; D011740:Pyrimidine Dimers; C404302:POLK protein, human; D000099270:Y-Family DNA Polymerases; C112338:Rad30 protein