title: The Escherichia coli proB gene corrects the proline auxotrophy of Saccharomyces cerevisiae pro1 mutants.
abstract: We constructed plasmids carrying the Escherichia coli proB gene that encodes gamma-glutamyl kinase, under the control of the yeast GAL1 promoter. This construction was carried out with both the wild-type proB+ gene and a mutant allele, proB74, that specifies an enzyme resistant to feedback inhibition by proline. Yeast pro1 mutants harboring these plasmids are proline prototrophs. We conclude that the pro1 mutation results in a deficiency in the gamma-glutamyl kinase activity in Saccharomyces cerevisiae. Expression of the proB74 allele in yeast resulted in enhanced resistance to the proline analogue L-azetidine-2-carboxylate and in a 2.4-fold elevation of the intracellular free proline levels. This result suggests that gamma-glutamyl kinase is the rate limiting step in proline biosynthesis in yeast.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
authors.forename: C S
authors.initials: CS
authors.lastname: Orser
authors.forename: B W
authors.initials: BW
authors.lastname: Goodner
authors.forename: M
authors.initials: M
authors.lastname: Johnston
authors.forename: S B
authors.initials: SB
authors.lastname: Gelvin
authors.forename: L N
authors.initials: LN
authors.lastname: Csonka
mesh_terms: D000483:Alleles; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D005838:Genotype; D009154:Mutation; D010770:Phosphotransferases / Q000235:genetics*; D017851:Phosphotransferases (Carboxyl Group Acceptor); D010957:Plasmids; D011392:Proline / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D011392:Proline; D010770:Phosphotransferases; D017851:Phosphotransferases (Carboxyl Group Acceptor); C020650:glutamate 5-kinase; D004262:DNA Restriction Enzymes