{PDOC50123}
{PS50123; CHER}
{BEGIN}
***************************************
* CheR-type methyltransferase profile *
***************************************

Chemotaxis in  bacteria  is  a  behavourial  response  that allows bacteria to
migrate towards  favorable  chemicals  and  away  from  unfavorable  ones. The
signaling activity   of   bacterial   chemotaxis  transmembrane  receptors  is
modulated by  reversible  methylation of specific glutamate residues predicted
to lie  within  a  coiled-coil region of the receptors cytoplasmic domain. The
level of  receptor  methylation  results  from  the  activities  of a specific
S-adenosyl-L-methionine-dependent methyltransferase  (EC  2.1.1.80), CheR, and
CheB methylesterase  (see <PDOC50122>) [1,2]. The CheR methyltransferase binds
to major  chemoreceptors  through  their  C-terminal pentapeptide motif NWETF,
which is distinct from the methylation site.

The crystal  structure  reveals  CheR  to  be  a  mixed  alpha/beta two-domain
protein. The  N-terminal  domain  consists  of four alpha-helices while the C-
terminal domain  has a modified Rossmann-type fold. The central seven-stranded
beta-sheet in  the  C-terminal  domain  of  CheR  is  commonly  found  in  all
S-adenosylmethionine-dependent methyltransferases.   However,  the  C-terminal
domain of  CheR  deviates  from  this  common fold by insertion of a subdomain
(beta-subdomain) consisting of a three-stranded beta-sheet and an alpha-helix.
The beta-subdomain  of  the CheR methyltransferase is a unique protein-protein
interaction structural   unit   found   specifically   in   methyltransferases
associated with bacterial receptors. The protein-protein recognition involving
this subdomain   occurs   through   extension   of   the   beta-sheet  of  the
methyltransferase by  addition of a beta-strand originating from the C-termini
of some chemotaxis receptors [3,4].

The profile we developed covers the entire CheR methyltransferase.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: January 2002 / First entry.

[ 1] Springer W.R., Koshland D.E. Jr.
     "Identification of a protein methyltransferase as the cheR gene
     product in the bacterial sensing system."
     Proc. Natl. Acad. Sci. U.S.A. 74:533-537(1977).
     PubMed=322131
[ 2] Simms S.A., Stock A.M., Stock J.B.
     "Purification and characterization of the
     S-adenosylmethionine:glutamyl methyltransferase that modifies membrane
     chemoreceptor proteins in bacteria."
     J. Biol. Chem. 262:8537-8543(1987).
     PubMed=3298235
[ 3] Djordjevic S., Stock A.M.
     "Crystal structure of the chemotaxis receptor methyltransferase CheR
     suggests a conserved structural motif for binding
     S-adenosylmethionine."
     Structure 5:545-558(1997).
     PubMed=9115443
[ 4] Djordjevic S., Stock A.M.
     "Chemotaxis receptor recognition by protein methyltransferase CheR."
     Nat. Struct. Biol. 5:446-450(1998).
     PubMed=9628482

--------------------------------------------------------------------------------
PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and
distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives
(CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html
--------------------------------------------------------------------------------

{END}