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Interplay between the membrane-associated UhpB and UhpC regulatory proteins
1Department of Microbiology, School of Medicine, University of Virginia, Charlottesville 22908.
Journal of Bacteriology
|August 1, 1993
Summary
Mutations in Escherichia coli regulatory genes uhpB and uhpC reveal that specific protein segments control sugar phosphate transport gene expression. These findings suggest UhpB and UhpC function as a complex in gene regulation.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- The Escherichia coli uhpT gene encodes a sugar phosphate transport protein, with its expression regulated by the uhpABC genes.
- The UhpA and UhpB proteins are components of a two-component regulatory system, while UhpC is homologous to transport proteins.
Purpose of the Study:
- To investigate the functional roles of specific segments within the membrane-associated UhpB and UhpC regulatory proteins.
- To elucidate the mechanism of uhpT gene regulation by analyzing mutations in the uhpABCT locus.
Main Methods:
- In vitro construction of mutations via oligonucleotide linker insertion at 44 sites within the uhpABCT locus.
- Assaying the effect of these mutations on uhpT-lacZ transcriptional reporter gene expression.
- Utilizing single-copy mutated uhp alleles on the chromosome for analysis.
Main Results:
- Insertions in uhpA or uhpT generally resulted in inactive transcription activation or transport.
- Approximately half of the insertions in uhpB and uhpC retained Uhp expression.
- Specific insertions in uhpB and uhpC led to high-level constitutive expression, independent of induction.
Conclusions:
- Transmembrane segments of UhpB may negatively regulate the kinase activity of its carboxyl portion.
- Constitutive uhpB mutants suggest a regulatory role for the N-terminal half of UhpB.
- UhpB and UhpC likely function as a complex in the signaling pathway for uhpT gene regulation.