title: The structures of thymidine kinase from herpes simplex virus type 1 in complex with substrates and a substrate analogue.
abstract: Thymidine kinase from Herpes simplex virus type 1 (TK) was crystallized in an N-terminally truncated but fully active form. The structures of TK complexed with ADP at the ATP-site and deoxythymidine-5'-monophosphate (dTMP), deoxythymidine (dT), or idoxuridine-5'-phosphate (5-iodo-dUMP) at the substrate-site were refined to 2.75 A, 2.8 A, and 3.0 A resolution, respectively. TK catalyzes the phosphorylation of dT resulting in an ester, and the phosphorylation of dTMP giving rise to an anhydride. The presented TK structures indicate that there are only small differences between these two modes of action. Glu83 serves as a general base in the ester reaction. Arg163 parks at an internal aspartate during ester formation and binds the alpha-phosphate of dTMP during anhydride formation. The bound deoxythymidine leaves a 35 A3 cavity at position 5 of the base and two sequestered water molecules at position 2. Cavity and water molecules reduce the substrate specificity to such an extent that TK can phosphorylate various substrate analogues useful in pharmaceutical applications. TK is structurally homologous to the well-known nucleoside monophosphate kinases but contains large additional peptide segments.
authors.affiliation: Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Freiburg im Breisgau, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Wild
authors.forename: T
authors.initials: T
authors.lastname: Bohner
authors.forename: G
authors.initials: G
authors.lastname: Folkers
authors.forename: G E
authors.initials: GE
authors.lastname: Schulz
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D003856:Deoxyuracil Nucleotides / Q000378:metabolism; D019281:Dimerization; D018259:Herpesvirus 1, Human / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017385:Sequence Homology; D013936:Thymidine / Q000378:metabolism; D013937:Thymidine Kinase / Q000737:chemistry* / Q000378:metabolism*; D013938:Thymidine Monophosphate / Q000378:metabolism
chemical_list: D003856:Deoxyuracil Nucleotides; D011994:Recombinant Proteins; C056075:iododeoxyuridylate; D013938:Thymidine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D013937:Thymidine Kinase; D013936:Thymidine