The structures of thymidine kinase from herpes simplex virus type 1 in complex with substrates and a substrate analogue.
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.
T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T20 T21 T22 T23 T24 T25 T26 T27 T28 T29 T2 T30 T31 T32 T33 T34 T35 T36 T37 T3 T4 T5 T6 T7 T8 T9
CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-Y CHEMICAL GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
dT idoxuridine-5'-phosphate 5-iodo-dUMP TK dT ester dTMP anhydride TK ester Thymidine aspartate ester alpha-phosphate dTMP anhydride N deoxythymidine TK thymidine Thymidine kinase phosphorylate TK nucleoside monophosphate kinases TK TK TK TK TK thymidine kinase TK nucleoside monophosphate ADP ATP deoxythymidine-5'-monophosphate dTMP deoxythymidine