Signal transduction in the Rhizobium meliloti dicarboxylic acid transport system.
The gene products of the Rhizobium meliloti dctB and dctD genes, which control the expression of the C4-dicarboxylic acid transporter DctA, were overproduced in Escherichia coli and purified. The purified sensor protein, DctB, was shown to have autophosphorylation activity in vitro and could subsequently phosphorylate the transcriptional activator, DctD. The presence of C4-dicarboxylic acids did not affect either reaction. In vitro experiments aimed at investigating 'crosstalk' between cognate components demonstrated that the phospho-transfer activity was specific between DctB and DctD. Studies on truncated versions of the DctB protein in vitro revealed that the cytoplasmic domain of DctB had strong autophosphorylation activity. Data from gel retardation experiments demonstrated that once the activator protein, DctD, was phosphorylated it had increased affinity for binding to the dctA promoter DNA.
Giblin
L
L
Microbiology Department, University College, Cork, Ireland.
Boesten
B
B
Turk
S
S
Hooykaas
P
P
O'Gara
F
F
D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D029382:Dicarboxylic Acid Transporters; D003998:Dicarboxylic Acids / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D016962:Sinorhizobium meliloti / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D029382:Dicarboxylic Acid Transporters; D003998:Dicarboxylic Acids; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D014157:Transcription Factors; C073786:dctA protein, Sinorhizobium meliloti; C073787:DCTB protein, Sinorhizobium; C073788:dctD protein, Rhizobium meliloti; D011494:Protein Kinases