title: Crystal structure of DNA photolyase from Escherichia coli.
abstract: Photolyase repairs ultraviolet (UV) damage to DNA by splitting the cyclobutane ring of the major UV photoproduct, the cis, syn-cyclobutane pyrimidine dimer (Pyr <> Pyr). The reaction is initiated by blue light and proceeds through long-range energy transfer, single electron transfer, and enzyme catalysis by a radical mechanism. The three-dimensional crystallographic structure of DNA photolyase from Escherichia coli is presented and the atomic model was refined to an R value of 0.172 at 2.3 A resolution. The polypeptide chain of 471 amino acids is folded into an amino-terminal alpha/beta domain resembling dinucleotide binding domains and a carboxyl-terminal helical domain; a loop of 72 residues connects the domains. The light-harvesting cofactor 5,10-methenyltetrahydrofolylpolyglutamate (MTHF) binds in a cleft between the two domains. Energy transfer from MTHF to the catalytic cofactor flavin adenine dinucleotide (FAD) occurs over a distance of 16.8 A. The FAD adopts a U-shaped conformation between two helix clusters in the center of the helical domain and is accessible through a hole in the surface of this domain. Dimensions and polarity of the hole match those of a Pyr <> Pyr dinucleotide, suggesting that the Pyr <> Pyr "flips out" of the helix to fit into this hole, and that electron transfer between the flavin and the Pyr <> Pyr occurs over van der Waals contact distance.
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235, USA.
authors.forename: H W
authors.initials: HW
authors.lastname: Park
authors.forename: S T
authors.initials: ST
authors.lastname: Kim
authors.forename: A
authors.initials: A
authors.lastname: Sancar
authors.forename: J
authors.initials: J
authors.lastname: Deisenhofer
mesh_terms: D000595:Amino Acid Sequence; D003196:Computer Graphics; D018360:Crystallography, X-Ray; D004249:DNA Damage; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport; D004926:Escherichia coli / Q000201:enzymology*; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005492:Folic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011740:Pyrimidine Dimers / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D011740:Pyrimidine Dimers; D005182:Flavin-Adenine Dinucleotide; C032418:5,11-methenyltetrahydrohomofolate; D005492:Folic Acid; D004255:Deoxyribodipyrimidine Photo-Lyase