PDBsum entry 1af7

Methyltransferase

PDB id: 1af7

Contents

Protein chain

274 a.a. *

Ligands

SAH

Waters ×111

* Residue conservation analysis

PDB id:

1af7

Name:

Methyltransferase

Title:

Cher from salmonella typhimurium

Structure:

Chemotaxis receptor methyltransferase cher. Chain: a. Engineered: yes. Other_details: structure includes s-adenosyl-l-homocysteine

Source:

Salmonella typhimurium. Organism_taxid: 602. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.00Å R-factor: 0.200 R-free: 0.280

Authors:

S.Djordjevic,A.M.Stock

Key ref:

S.Djordjevic and A.M.Stock (1997). Crystal structure of the chemotaxis receptor methyltransferase CheR suggests a conserved structural motif for binding S-adenosylmethionine. Structure, 5, 545-558. PubMed id: 9115443 DOI: 10.1016/S0969-2126(97)00210-4

Date:

22-Mar-97 Release date: 28-Jan-98

Protein chain

P07801  (CHER_SALTY) -  Chemotaxis protein methyltransferase from Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)

Seq: 288 a.a.

Struc: 274 a.a.

Enzyme reactions

• Enzyme class: E.C.2.1.1.80 - protein-glutamate O-methyltransferase.
• Reaction: L-glutamyl-[protein] + S-adenosyl-L-methionine = [protein]-L-glutamate 5-O-methyl ester + S-adenosyl-L-homocysteine

L-glutamyl-[protein] + S-adenosyl-L-methionine = [protein]-L-glutamate 5-O-methyl ester + S-adenosyl-L-homocysteine (Bound ligand (Het Group name = SAH) corresponds exactly)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

DOI no: 10.1016/S0969-2126(97)00210-4

Structure 5:545-558 (1997)

PubMed id: 9115443

Crystal structure of the chemotaxis receptor methyltransferase CheR suggests a conserved structural motif for binding S-adenosylmethionine.

S.Djordjevic, A.M.Stock.

ABSTRACT

BACKGROUND: Flagellated bacteria swim towards favorable chemicals and away from deleterious ones. The sensing of chemoeffector gradients involves chemotaxis receptors, transmembrane proteins that detect stimuli through their periplasmic domains and transduce signals via their cytoplasmic domains to the downstream signaling components. Signaling outputs from chemotaxis receptors are influenced both by the binding of the chemoeffector ligand to the periplasmic domain and by methylation of specific glutamate residues on the cytoplasmic domain of the receptor. Methylation is catalyzed by CheR, an S-adenosylmethionine-dependent methyltransferase. CheR forms a tight complex with the receptor by binding a region of the receptors that is distinct from the methylation site. CheR belongs to a broad class of enzymes involved in the methylation of a variety of substrates. Until now, no structure from the class of protein methyltransferases has been characterized. RESULTS: The structure of the Salmonella typhimurium chemotaxis receptor methyltransferase CheR bound to S-adenosylhomocysteine, a product and inhibitor of the methylation reaction, has been determined at 2.0 A resolution. The structure reveals CheR to be a two-domain protein, with a smaller N-terminal helical domain linked through a single polypeptide connection to a larger C-terminal alpha/beta domain. The C-terminal domain has the characteristics of a nucleotide-binding fold, with an insertion of a small antiparallel beta sheet subdomain. The S-adenosylhomocysteine-binding site is formed mainly by the large domain, with contributions from residues within the N-terminal domain and the linker region. CONCLUSIONS: The CheR structure shares some structural similarities with small molecule DNA and RNA methyltransferases, despite a lack of sequence similarity among them. In particular, there is significant structural preservation of the S-adenosylmethionine-binding clefts; the specific length and conformation of a loop in the alpha/beta domain seems to be required for S-adenosylmethionine binding within these enzymes. Unique structural features of CheR, such as the beta subdomain, are probably necessary for CheR's specific interaction with its substrates, the bacterial chemotaxis receptors.

Selected figure(s)

Figure 4.
Figure 4. S-adenosylhomocysteine-binding site in CheR. (a) A stereo diagram (MOLSCRIPT; [57]) of the AdoHcy-binding site. Only sidechain atoms are included in the figure except for the residues that form hydrogen bonds with AdoHcy through mainchain atoms. Hydrogen bonds are represented by dashed lines. (b) A schematic view of the contacts identified in the crystal structure of the CheR-AdoHcy complex. Hydrogen bonds are drawn with dashed lines and covalent bonds are shown as solid lines connecting the solid spheres that denote atoms. Residues within the hydrophobic pocket that accommodates the adenine portion of AdoHcy are represented by parallel curved lines. Sulfur atoms are shown in green, other atom colors are the same as Figure 2.

The above figure is reprinted by permission from Cell Press: Structure (1997, 5, 545-558) copyright 1997.

Figure was selected by an automated process.