Three-dimensional structure of thymidine phosphorylase from Escherichia coli at 2.8 A resolution.
The three-dimensional structure of thymidine phosphorylase from Escherichia coli has been determined at 2.8 A resolution using multiple-isomorphous-replacement techniques. The amino acid sequence deduced from the deoA DNA sequence is also reported. Thymidine phosphorylase exists in the crystal as an S-shaped dimer in which the subunits are related by a crystallographic 2-fold axis. Each subunit is composed of a small alpha-helical domain of six helices and a large alpha/beta domain. The alpha/beta domain includes a six-stranded mixed beta-sheet and a four-stranded antiparallel beta-sheet. The active site has been identified by difference Fourier analyses of the binding of thymine and thymidine and lies in a cavity between the small and large domains. The central beta-sheet is splayed open to accommodate a putative phosphate-binding site which is probably occupied by a sulfate ion in the crystal.
Walter
M R
MR
Department of Biochemistry, University of Alabama, Birmingham 35294.
Cook
W J
WJ
Cole
L B
LB
Short
S A
SA
Koszalka
G W
GW
Krenitsky
T A
TA
Ealick
S E
SE
D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D003460:Crystallization; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010430:Pentosyltransferases / Q000235:genetics / Q000302:isolation & purification; D011487:Protein Conformation; D013939:Thymidine Phosphorylase / Q000235:genetics / Q000302:isolation & purification; D014961:X-Ray Diffraction
D004269:DNA, Bacterial; D008024:Ligands; D010430:Pentosyltransferases; D013939:Thymidine Phosphorylase