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Published June 1, 1988 | public
Journal Article Open

Cloning of the C-terminal cytoplasmic fragment of the tar protein and effects of the fragment on chemotaxis of Escherichia coli


A gene encoding only the C-terminal portion of the receptor-transducer protein Tar of Escherichia coli was constructed. The gene product was detected and localized in the cytoplasmic fraction of the cell by immunoblotting with anti-Tar antibodies. The C-terminal fragments from wild-type and mutant tar genes were characterized in vivo. The C-terminal fragment generated from tar-526, a mutation that results in a dominant "tumble" phenotype, was found to be deamidated and methylated by the CheB and CheR proteins, respectively. The C-terminal fragment derived from a wild-type gene was poorly deamidated, and the C-terminal fragment derived from tar-529, a dominant mutant with a "smooth swimming" phenotype, was not apparently modified. Cells carrying the C-terminal fragment with the tar-526 mutation as the sole receptor-transducer protein showed a high frequency of tumbling and chemotaxis responses to changes in intracellular pH. These results suggest that the cytoplasmic C-terminal fragment of Tar retains some of the functions of the whole protein in vivo.

Additional Information

Copyright © 1988, American Society for Microbiology. Received 2 November 1987/Accepted 5 March 1988. We thank H. C. Berg and J. S. Parkinson for providing E. coli strains, J. Brosius for providing plasmids, and R. Bourret, J. Fred Hess, N. Kaplan, and R. Miake-Lye for critical reading of the manuscript. This work was supported by Public Health Service grant AI19296 from the National Institutes of Health.


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