title: Essential role of the hprK gene in Ralstonia eutropha H16.
abstract: Ralstonia eutropha H16 possesses an incomplete phosphoenolpyruvate (PEP):sugar phosphotransferase system (PTS) composed of EI, HPr, EIIA(Ntr) (PtsN) and EIIA(Man) (PtsM). We could show that in vitro the incomplete PTS phosphorylation cascade is partially functional. HPr becomes phosphorylated by PEP and EI, and transfers the phosphoryl group to EIIA(Ntr), but only extremely slowly to EIIA(Man). Components of this system have previously been shown to regulate the metabolism of polyhydroxybutyrate. Downstream from ptsN this organism contains an hprK gene, which codes for a homologue of HPr kinase/phosphorylase. We show that this enzyme phosphorylates HPr using ATP as phosphoryl donor. Interestingly, hprK appeared to be essential in R. eutropha because this gene could not be deleted in the wild-type strain, but could be deleted in mutants lacking ptsH or ptsI. This suggests that an increase in the HPr and/or P approximate His-HPr concentrations might be responsible for the growth defect. To test this hypothesis, various ptsH alleles were introduced into the ptsH hprK double mutant. Complementation of this mutant was possible only with the ptsH(His15Ala) allele, but not with the wild-type or ptsH(Ser46Ala) alleles. We conclude that elevated amounts of His-15-phosphorylated HPr, formed in the hprK mutant, are responsible for its growth defect.
authors: Abteilung für Allgemeine Mikrobiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Göttingen, Germany.
authors: Désirée
authors: D
authors: Krausse
authors: Katja
authors: K
authors: Hunold
authors: Bernhard
authors: B
authors: Kusian
authors: Oliver
authors: O
authors: Lenz
authors: Jörg
authors: J
authors: Stülke
authors: Botho
authors: B
authors: Bowien
authors: Josef
authors: J
authors: Deutscher
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D020118:Cupriavidus necator / Q000235:genetics* / Q000502:physiology; D017353:Gene Deletion; D020043:Genes, Essential; D005816:Genetic Complementation Test; D006801:Humans; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D000255:Adenosine Triphosphate; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases