N-terminal half of CheB is involved in methylesterase response to negative chemotactic stimuli in Escherichia coli.
AUTOR(ES)
Stewart, R C
RESUMO
The chemotactic receptor-transducer proteins of Escherichia coli are responsible for directing the swimming behavior of cells by signaling for either straight swimming or tumbling in response to chemostimuli. The signaling states of these proteins are affected not only by the concentrations of various stimuli but also by the extent to which they have been methylated at specific glutamyl residues. The activities of a chemotaxis-specific methyltransferase (CheR) and a chemotaxis-specific methylesterase (CheB) are regulated in response to chemotactic stimuli to enable sensory adaptation to unchanging levels of stimuli by appropriately shifting the signaling states of the transducer proteins. For CheB this regulation involves a feedback loop that requires some of the components making up the chemotactic signal transduction machinery of the cell. This feedback loop causes the methylesterase activity of CheB to decrease transiently in response to attractant stimuli and to increase transiently in response to negative stimuli (repellent addition or attractant removal). In this report we demonstrate that the methylesterase response to negative stimuli involves the N-terminal half of the CheB protein, whereas the response to positive stimuli does not require this segment of the protein. Both aspects of the methylesterase response to positive stimuli does not require this segment of the protein. Both aspects of the methylesterase response require CheA. In addition, we demonstrate that mutant forms of CheB lacking methylesterase activity can adversely affect the swimming behavior and chemotactic ability of cells and can markedly diminish modulation of the wild-type methylesterase activity in response to negative stimuli. The significance of these results is discussed in relation to the recent demonstration of phosphoryl transfer from CheA to CheB (J. F. Hess, K. Oosawa, N. Kaplan, and M. I. Simon, Cell 53:79-87, 1988) and the discovery of sequence homology between the N-terminal half of CheB and CheY (A. Stock, D. E. Koshland, Jr., and J. Stock, Proc. Natl. Acad. Sci. USA 82:7989-7993, 1985).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=211675Documentos Relacionados
- Inversion of aerotactic response in Escherichia coli deficient in cheB protein methylesterase.
- Clustering of the Chemoreceptor Complex in Escherichia coli Is Independent of the Methyltransferase CheR and the Methylesterase CheB
- Requirement of the cheB function for sensory adaptation in Escherichia coli.
- Transient response to chemotactic stimuli in Escherichia coli.
- Mutations that affect control of the methylesterase activity of CheB, a component of the chemotaxis adaptation system in Escherichia coli.