title: Expression, purification, and characterization of uracil phosphoribosyltransferase from Toxoplasma gondii.
abstract: The coding region derived from a full-length CDNA spanning the uracil phosphoribosyltransferase (UPRT) gene of Toxoplasma gondii has been ligated into a bacterial expression vector and overexpressed in E. coli. Recombinant UPRT protein migrated with a molecular mass of 27 kDa on SDS polyacrylamide gels and was purified to homogeneity by conventional protein purification techniques. In solution, UPRT behaved as a monomer and exhibited K(m)app values of 3.5 microM for uracil and 243 microM for phosphoribosylpyrophosphate, respectively. Other naturally occurring pyrimidine or purine bases were not recognized as substrates. [14C]Uracil phosphoribosylation was inhibited by 5-fluorouracil with a Ki value of 25 microM and was not activated by GTP. Ample quantities of recombinant enzyme are now available for biochemical and structural studies, facilitating evaluation of UPRT as a possible therapeutic target.
authors.affiliation: Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, Portland 97201-3098, USA.
authors.forename: D
authors.initials: D
authors.lastname: Carter
authors.forename: R G
authors.initials: RG
authors.lastname: Donald
authors.forename: D
authors.initials: D
authors.lastname: Roos
authors.forename: B
authors.initials: B
authors.lastname: Ullman
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D017125:Genes, Protozoan; D007700:Kinetics; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D010430:Pentosyltransferases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D014122:Toxoplasma / Q000201:enzymology* / Q000235:genetics*
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D010430:Pentosyltransferases; C023269:uracil phosphoribosyltransferase