Orotate phosphoribosyltransferase (OPRTase) is involved in the biosynthesis of pyrimidine nucleotides. Alpha-D-ribosyldiphosphate 5-phosphate (PRPP) and orotate are utilized to form pyrophosphate and orotidine 5'-monophosphate (OMP) in the presence of divalent cations, preferably Mg2+. OMP is thereafter converted to uridine 5'-monophosphate by OMP decarboxylase. We have determined the 1.9 angstrom structure of Francisella tularensis subsp. tularensis SCHU S4 OPRTase (PyrE). The OPRTase three-dimensional structure reveals two major features: a core five-stranded alpha/beta twisted sheet and an N-terminal region that partially covers the C-terminal portion of the core. PRTases show a very high degree of base specificity.
Purines, pyrimidines, nucleosides, and nucleotides; subcategory: Pyrimidine ribonucleotide biosynthesis