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The PTS Ntr system globally regulates ATP‐dependent transporters in Rhizobium leguminosarum
Author(s) -
Prell J.,
Mulley G.,
Haufe F.,
White J. P.,
Williams A.,
Karunakaran R.,
Downie J. A.,
Poole P. S.
Publication year - 2012
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2012.08014.x
Subject(s) - rhizobium leguminosarum , mutant , biology , transporter , atp binding cassette transporter , phosphorylation , microbiology and biotechnology , biochemistry , atp hydrolysis , escherichia coli , bacteria , enzyme , genetics , gene , atpase , symbiosis , rhizobiaceae
Summary 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.