Action of receiver and activator modules of UhpA in transcriptional control of the Escherichia coli sugar phosphate transport system.
Induction of the sugar-phosphate transport system in Escherichia coli by external glucose-6-phosphate is regulated by the UhpABC regulatory proteins. UhpA protein is required for uhpT transcription and is related to response regulators of two-component regulatory systems. UhpA and its homologues appear to be composed of two modules: the receiver module which contains the putative site of phosphorylation, and the activation module whose predicted helix-turn-helix motif is related to that present in many transcription activators. The roles of the two modules were examined by analysis of the regulatory consequences of uhpA deletion mutations generated by in vitro manipulations and missense mutations selected for independence from the requirement for UhpB kinase activity. Deletion of even seven amino acids from the C-terminus resulted in complete loss of transcription activation at the uhpT promoter. Overexpression of all C-terminal truncations that left intact the receiver module (residues 1-120) exhibited strong dominant-negative interference with a chromosomal uhpA+ allele. The genetic requirements for interference indicated that the overexpressed receiver module competed with intact UhpA for phosphate residues carried on UhpB. The site of phosphorylation of UhpA is not necessary for uhp activation by overexpressed UhpA but is necessary for UhpA action at normal levels of UhpA or for interference by the truncated species.
Webber
C A
CA
Department of Microbiology, School of Medicine, University of Virginia, Charlottesville 22908, USA.
Kadner
R J
RJ
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D017353:Gene Deletion; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D016297:Mutagenesis, Site-Directed; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics; D010641:Phenotype; D010770:Phosphotransferases; D011401:Promoter Regions, Genetic / Q000235:genetics; D013403:Sugar Phosphates / Q000378:metabolism*; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D010455:Peptides; D013403:Sugar Phosphates; C489848:UhpA protein, E coli; C063498:UhpT protein, E coli; C080370:UhpA protein, Bacteria; C086586:uhpB protein, Bacteria; D010770:Phosphotransferases