|PROSITE documentation PDOC00465|
Bacterial chemotactic-signal transducers [1,2] are proteins that respond to changes in the concentration of attractants and repellents in the environment, and transduce a signal from the outside to the inside of the cell. These proteins undergo two covalent modifications: deamidation and reversible methylation. Attractants increase the level of methylation while repellents decrease it. The methyl groups are added by the methyl-transferase cheR and are removed by the methylesterase cheB.
In Escherichia coli and related bacteria, there are four different chemotactic transducers:
In Enterobacter aerogenes  there are at least two different chemotactic transducers:
In Salmonella typhimurium , in addition to tar, there is:
All these proteins are composed of the same structural domains: a N-terminal region that resembles a signal peptide, but which is not removed from the mature protein and serves as a membrane-spanning region; a periplasmic domain of about 160 amino acids that forms the receptor domain; a second transmembrane region and finally a C-terminal cytoplasmic domain of about 300 amino acids which contains the methylation sites.
The methyl-accepting sites are specific glutamate residues (some of these sites are translated as glutamine but are irreversibly deamidated by cheB). They are clustered in two regions of the cytoplasmic domain . As a signature pattern we have selected the first of these two regions.Last update:
September 2002 / text revised; profile added.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Stewart R.C. Dahlquist F.W.|
|Source||Chem. Rev. 87:997-1025(1987).|
|Title||The bacterial chemosensory system.|
|Source||Can. J. Microbiol. 34:466-474(1988).|
|3||Authors||Dahl M.K. Boos W. Manson M.D.|
|Title||Evolution of chemotactic-signal transducers in enteric bacteria.|
|Source||J. Bacteriol. 171:2361-2371(1989).|
|4||Authors||Yamamoto K. Imae Y.|
|Title||Cloning and characterization of the Salmonella typhimurium-specific chemoreceptor Tcp for taxis to citrate and from phenol.|
|Source||Proc. Natl. Acad. Sci. U.S.A. 90:217-221(1993).|
|5||Authors||Rice M.S. Dahlquist F.W.|
|Title||Sites of deamidation and methylation in Tsr, a bacterial chemotaxis sensory transducer.|
|Source||J. Biol. Chem. 266:9746-9753(1991).|