title: Phosphorylation of HPr by the bifunctional HPr Kinase/P-ser-HPr phosphatase from Lactobacillus casei controls catabolite repression and inducer exclusion but not inducer expulsion.
abstract: We have cloned and sequenced the Lactobacillus casei hprK gene encoding the bifunctional enzyme HPr kinase/P-Ser-HPr phosphatase (HprK/P). Purified recombinant L. casei HprK/P catalyzes the ATP-dependent phosphorylation of HPr, a phosphocarrier protein of the phosphoenolpyruvate:carbohydrate phosphotransferase system at the regulatory Ser-46 as well as the dephosphorylation of seryl-phosphorylated HPr (P-Ser-HPr). The two opposing activities of HprK/P were regulated by fructose-1,6-bisphosphate, which stimulated HPr phosphorylation, and by inorganic phosphate, which stimulated the P-Ser-HPr phosphatase activity. A mutant producing truncated HprK/P was found to be devoid of both HPr kinase and P-Ser-HPr phosphatase activities. When hprK was inactivated, carbon catabolite repression of N-acetylglucosaminidase disappeared, and the lag phase observed during diauxic growth of the wild-type strain on media containing glucose plus either lactose or maltose was strongly diminished. In addition, inducer exclusion exerted by the presence of glucose on maltose transport in the wild-type strain was abolished in the hprK mutant. However, inducer expulsion of methyl beta-D-thiogalactoside triggered by rapidly metabolizable carbon sources was still operative in ptsH mutants altered at Ser-46 of HPr and the hprK mutant, suggesting that, in contrast to the model proposed for inducer expulsion in gram-positive bacteria, P-Ser-HPr might not be involved in this regulatory process.
authors.affiliation: Laboratoire de Génétique des Microorganismes, 78850 Thiverval-Grignon, France.
authors.forename: V
authors.initials: V
authors.lastname: Dossonnet
authors.forename: V
authors.initials: V
authors.lastname: Monedero
authors.forename: M
authors.initials: M
authors.lastname: Zagorec
authors.forename: A
authors.initials: A
authors.lastname: Galinier
authors.forename: G
authors.initials: G
authors.lastname: Pérez-Martínez
authors.forename: J
authors.initials: J
authors.lastname: Deutscher
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007780:Lacticaseibacillus casei / Q000201:enzymology* / Q000235:genetics; D008320:Maltose / Q000378:metabolism; D008756:Methylgalactosides / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010710:Phosphates / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D020218:Response Elements; D013862:Thiogalactosides / Q000378:metabolism; D014166:Transferases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D008756:Methylgalactosides; D010710:Phosphates; D012097:Repressor Proteins; D013862:Thiogalactosides; C069286:catabolite control proteins, bacteria; C009468:thiomethylgalactoside; D008320:Maltose; D014166:Transferases; C042308:phosphatidylglycerol glyceryl transferase; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases; C110846:YvoE protein, Bacillus substilis; D010749:Phosphoprotein Phosphatases; D000118:Acetylglucosaminidase; D005947:Glucose