| First Author | Langdon SD | Year | 1987 |
| Journal | J Biol Chem | Volume | 262 |
| Issue | 27 | Pages | 13359-65 |
| PubMed ID | 3308878 | Mgi Jnum | J:307214 |
| Mgi Id | MGI:6720228 | Doi | 10.1016/S0021-9258(18)45209-X |
| Citation | Langdon SD, et al. (1987) Study of the kinetic and physical properties of the orotidine-5'-monophosphate decarboxylase domain from mouse UMP synthase produced in Saccharomyces cerevisiae. J Biol Chem 262(27):13359-65 |
| abstractText | In mammals, the bifunctional protein UMP synthase contains the final two enzymatic activities, orotate phosphoribosyltransferase and orotidine-5'-monophosphate decarboxylase (ODCase), for de novo biosynthesis of UMP. The plasmid pMEJ contains a cDNA for the ODCase domain of mouse Ehrlich ascites UMP synthase. The cDNA from pMEJ was joined to the Saccharomyces cerevisiae iso-1-cytochrome c (CYC1) promoter and the first four CYC1 coding nucleotides in the plasmid pODCcyc. ODCase-deficient yeast cells (HF200x1) transformed with pODCcyc expressed an active ODCase domain with a specific activity of 20 nmol/min/mg in cell extracts. The expressed ODCase domain has a lower affinity for the substrate orotidine 5'-monophosphate and the inhibitor 6-azauridine 5'-monophosphate than intact UMP synthase or an ODCase domain isolated after proteolysis of homogenous UMP synthase. Sucrose density gradient sedimentation experiments showed that the expressed ODCase domain forms a dimer in the presence of ligands which bind at the catalytic site. These studies support the existence of an ODCase structural domain which contains the ODCase catalytic site and a dimerization surface of UMP synthase, but the domain may not have the regulatory site required to form the altered dimer form. |
