Protein-glutamate O-methyltransferase
CheR is a methyltransferase involved in methylation of the membrane-bound methyl-accepting chemotaxis proteins (MCP) to form gamma-glutamyl methyl ester residues. This reaction is important for modulating a bacterium's response to a gradient of attractant or repellent.
Reference Protein and Structure
- Sequence
-
P07801
(2.1.1.80)
(Sequence Homologues)
(PDB Homologues)
- Biological species
-
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 (Bacteria)
- PDB
-
1af7
- CHER FROM SALMONELLA TYPHIMURIUM
(2.0 Å)
- Catalytic CATH Domains
-
1.10.155.10
3.40.50.150
(see all for 1af7)
Enzyme Reaction (EC:2.1.1.80)
+
→
+
Alternative enzyme names: S-adenosylmethionine-glutamyl methyltransferase, S-adenosylmethionine:protein-carboxyl O-methyltransferase, MCP methyltransferase I, MCP methyltransferase II, Methyl-accepting chemotaxis protein O-methyltransferase, Methyl-accepting chemotaxis protein methyltransferase II, Protein O-methyltransferase, Protein carboxyl-O-methyltransferase, Protein carboxyl-methylase, Protein carboxylmethyltransferase II, Protein carboxymethylase, Protein carboxymethyltransferase, Protein methylase II, Protein methyltransferase II, Protein(aspartate)methyltransferase, Protein(carboxyl)methyltransferase,
Enzyme Mechanism
Introduction
The methyl transfer from SAM to one of the glutamate residues of the substrate follows an SN2 mechanism. The mechanism proceeds with little or no direct involvement of residues in the active site, although the binding residues for SAM are known to be highly conserved.
Catalytic Residues Roles
| UniProt | PDB* (1af7) | ||
| Arg53 | Arg53(43)A | May stabilise or position methylatable γ-carboxlate of glutamate by ion-pair, salt-bridge or other electrostatic interaction. | electrostatic stabiliser |
| Asp154 | Asp154(144)A | Plays an essential role in catalysis, by polarization of water molecule that was placed close to the methyl group of SAM | activator |
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file;
y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain;
C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.
Chemical Components
References
- Simms SA et al. (1991), J Biol Chem, 266, 12741-12746. The kinetic mechanism of S-adenosyl-L-methionine: glutamylmethyltransferase from Salmonella typhimurium. PMID:2061337.
- Batra M et al. (2016), J Struct Biol, 196, 364-374. Crystal structure of pentapeptide-independent chemotaxis receptor methyltransferase (CheR) reveals idiosyncratic structural determinants for receptor recognition. DOI:10.1016/j.jsb.2016.08.005. PMID:27544050.
- Batra M et al. (2015), Int J Biol Macromol, 77, 168-180. In silico and proteomic analysis of protein methyltransferase CheR from Bacillus subtilis. DOI:10.1016/j.ijbiomac.2015.03.023. PMID:25799883.
- Shiomi D et al. (2002), J Biol Chem, 277, 42325-42333. Dual Recognition of the Bacterial Chemoreceptor by Chemotaxis-specific Domains of the CheR Methyltransferase. DOI:10.1074/jbc.m202001200. PMID:12101179.
- Djordjevic S et al. (1997), Structure, 5, 545-558. Crystal structure of the chemotaxis receptor methyltransferase CheR suggests a conserved structural motif for binding S-adenosylmethionine. DOI:10.1016/s0969-2126(97)00210-4.
Catalytic Residues Roles
| Residue | Roles |
|---|---|
| Asp154(144)A | activator |
| Arg53(43)A | electrostatic stabiliser |