title: The PTS(Ntr)  system globally regulates ATP-dependent transporters in Rhizobium leguminosarum.
abstract: Mutation of ptsP encoding EI(Ntr)  of the PTS(Ntr)  system in Rhizobium leguminosarum strain Rlv3841 caused a pleiotropic phenotype as observed with many bacteria. The mutant formed dry colonies and grew poorly on organic nitrogen or dicarboxylates. Most strikingly the ptsP mutant had low activity of a broad range of ATP-dependent ABC transporters. This lack of activation, which occurred post-translationally, may explain many of the pleiotropic effects. In contrast proton-coupled transport systems were not inhibited in a ptsP mutant. Regulation by PtsP also involves two copies of ptsN that code for EIIA(Ntr) , resulting in a phosphorylation cascade. As in Escherichia coli, the Rlv3841 PTS(Ntr)  system also regulates K(+)  homeostasis by transcriptional activation of the high-affinity ATP-dependent K(+)  transporter KdpABC. This involves direct interaction of a two-component sensor regulator pair KdpDE with unphosphorylated EIIA(Ntr) . Critically, ptsP mutants, which cannot phosphorylate PtsN1 or PtsN2, had a fully activated KdpABC transporter. This is the opposite pattern from that observed with ABC transporters which apparently require phosphorylation of PtsN. These results suggest that ATP-dependent transport might be regulated via PTS(Ntr)  responding to the cellular energy charge. ABC transport may be inactivated at low energy charge, conserving ATP for essential processes including K(+)  homeostasis.
authors.affiliation: Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Prell
authors.forename: G
authors.initials: G
authors.lastname: Mulley
authors.forename: F
authors.initials: F
authors.lastname: Haufe
authors.forename: J P
authors.initials: JP
authors.lastname: White
authors.forename: A
authors.initials: A
authors.lastname: Williams
authors.forename: R
authors.initials: R
authors.lastname: Karunakaran
authors.forename: J A
authors.initials: JA
authors.lastname: Downie
authors.forename: P S
authors.initials: PS
authors.lastname: Poole
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D015964:Gene Expression Regulation, Bacterial; D006706:Homeostasis; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D016961:Rhizobium leguminosarum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D011494:Protein Kinases; C075616:kdpD protein, Bacteria; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D011188:Potassium