Proline biosynthesis in Saccharomyces cerevisiae: analysis of the PRO3 gene, which encodes delta 1-pyrroline-5-carboxylate reductase.
The PRO3 gene of Saccharomyces cerevisiae encodes the 286-amino-acid protein delta 1-pyrroline-5-carboxylate reductase [L-proline:NAD(P+) 5-oxidoreductase; EC 1.5.1.2], which catalyzes the final step in proline biosynthesis. The protein has substantial similarity to the pyrroline carboxylate reductases of diverse bacterial species, soybean, and humans. Using RNA hybridization and measurements of enzyme activity, we have determined that the expression of the PRO3 gene appears to be constitutive. It is not repressed by the pathway end product (proline), induced by the initial substrate (glutamate), or regulated by the general control system. Its expression is not detectably altered when cells are grown in a wide range of nitrogen sources or when glycerol and ethanol replace glucose as the carbon source. The possibility that this enzyme has other functions in addition to proline biosynthesis is discussed.
Brandriss
M C
MC
Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, Newark 07103.
Falvey
D A
DA
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000494:pharmacology; D000640:Amitrole / Q000494:pharmacology; D001483:Base Sequence; D003470:Culture Media / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects / Q000235:genetics; D008969:Molecular Sequence Data; D011392:Proline / Q000096:biosynthesis* / Q000494:pharmacology; D011762:Pyrroline Carboxylate Reductases / Q000096:biosynthesis / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D001616:beta-Galactosidase / Q000096:biosynthesis; D000097502:delta-1-Pyrroline-5-Carboxylate Reductase
D000596:Amino Acids; D000640:Amitrole; D003470:Culture Media; D011392:Proline; D011762:Pyrroline Carboxylate Reductases; D001616:beta-Galactosidase; D000097502:delta-1-Pyrroline-5-Carboxylate Reductase