PMID:7990135
| Citation |
Jin, T and Inouye, M (1994) Transmembrane signaling. Mutational analysis of the cytoplasmic linker region of Taz1-1, a Tar-EnvZ chimeric receptor in Escherichia coli. J. Mol. Biol. 244:477-81 |
|---|---|
| Abstract |
Taz1-1 is Tar-EnvZ chimeric receptor that is able to induce ompC-lacZ expression in response to aspartate. Previous studies indicated that aspartate binding to the receptor domain of the Taz1-1 receptor modulated the ratio of kinase and phosphatase activities of the cytoplasmic signaling domain. The 80-residue segment of chemoreceptors that is located between the second transmembrane domain and the signaling domain was defined as the linker region. The Taz1-1 chimeric receptor contains 43 amino acid residues of the Tar linker region. In order to understand further the function of the linker region in transmembrane signaling, site-directed random mutagenesis was carried out on the conserved Ala231 in the linker region. Substitution mutations with Val, Glu, Gly, Thr, Lys and His gave the locked "off-mode" form (low ompC-lacZ expression), and substitution mutations with Ile and Leu resulted in the locked "on-mode" form (constitutive ompC-lacZ expression). All the mutant Taz1-1 receptors still retained both OmpR kinase and phospho-OmpR phosphatase activities. Interestingly Taz1N6, a kinase defective mutant, was able to complement with Taz1H1, a phosphatase defective mutant, carrying an off-mode mutant at position 231 to restore Asp-inducible ompC-lacZ expression, but not with Taz1H1 carrying an on-mode mutation. These results suggest that the residue at position 231 in Taz1-1 plays a key role in signal transduction. |
| Links |
PubMed Online version:10.1006/jmbi.1994.1746 |
| Keywords |
Amino Acid Sequence; Bacterial Outer Membrane Proteins/chemistry; Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Base Sequence; Chemoreceptor Cells; DNA Mutational Analysis; Escherichia coli/chemistry; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Genetic Complementation Test; Membrane Proteins/chemistry; Membrane Proteins/genetics; Molecular Sequence Data; Multienzyme Complexes; Mutagenesis, Site-Directed; Phosphoprotein Phosphatases/metabolism; Protein Kinases; Receptors, Cell Surface; Recombinant Fusion Proteins/chemistry; Recombinant Fusion Proteins/metabolism; Signal Transduction |
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