PROSITE documentation PDOC00465Bacterial chemotaxis sensory transducers signature and profile
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:
- tsr, responsible for taxis to the attractants L-serine and related amino acids and away from the repellents leucine, indole, and weak acids.
- tar, responsible for taxis to the attractants L-aspartate and related amino and dicarboxylic acids. Also mediates taxis to the attractant maltose via an interaction with the periplasmic maltose-binding protein. Mediates taxis away from the repellents cobalt and nickel.
- trg, responsible for taxis to ribose and galactose via an interaction with the periplasmic ribose- or galactose-binding proteins.
- tap, responsible for taxis towards dipeptides via an interaction with the periplasmic dipeptide-binding protein.
In Enterobacter aerogenes [3] there are at least two different chemotactic transducers:
- tsr, responsible for taxis to the attractant L-serine.
- tas, responsible for taxis to the attractant L-aspartate.
In Salmonella typhimurium [4], in addition to tar, there is:
- tcp, responsible for taxis to the attractant citrate.
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 [5]. As a signature pattern we have selected the first of these two regions.
Last update:September 2002 / text revised; profile added.
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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). |
2 | Authors | Hazelbauer G.L. |
Title | The bacterial chemosensory system. | |
Source | Can. J. Microbiol. 34:466-474(1988). | |
PubMed ID | 3052756 |
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). | |
PubMed ID | 2496104 |
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). | |
PubMed ID | 8419927 |
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). | |
PubMed ID | 2033064 |
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