Enzymes
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Namehelp_outline
L-glutamyl-[protein]
Identifier
RHEA-COMP:10208
Reactive part
help_outline
- Name help_outline L-glutamate residue Identifier CHEBI:29973 Charge -1 Formula C5H6NO3 SMILEShelp_outline C(*)(=O)[C@@H](N*)CCC(=O)[O-] 2D coordinates Mol file for the small molecule Search links Involved in 11 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline S-adenosyl-L-methionine Identifier CHEBI:59789 Charge 1 Formula C15H23N6O5S InChIKeyhelp_outline MEFKEPWMEQBLKI-AIRLBKTGSA-O SMILEShelp_outline C[S+](CC[C@H]([NH3+])C([O-])=O)C[C@H]1O[C@H]([C@H](O)[C@@H]1O)n1cnc2c(N)ncnc12 2D coordinates Mol file for the small molecule Search links Involved in 854 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Namehelp_outline
[protein]-L-glutamate 5-O-methyl ester
Identifier
RHEA-COMP:10311
Reactive part
help_outline
- Name help_outline L-glutamate O5-methyl ester residue Identifier CHEBI:82795 Charge 0 Formula C6H9NO3 SMILEShelp_outline COC(=O)CC[C@H](N-*)C(-*)=O 2D coordinates Mol file for the small molecule Search links Involved in 2 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline S-adenosyl-L-homocysteine Identifier CHEBI:57856 Charge 0 Formula C14H20N6O5S InChIKeyhelp_outline ZJUKTBDSGOFHSH-WFMPWKQPSA-N SMILEShelp_outline Nc1ncnc2n(cnc12)[C@@H]1O[C@H](CSCC[C@H]([NH3+])C([O-])=O)[C@@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 779 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:24452 | RHEA:24453 | RHEA:24454 | RHEA:24455 | |
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Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Physiological sites of deamidation and methyl esterification in sensory transducers of Halobacterium salinarum.
Koch M.K., Staudinger W.F., Siedler F., Oesterhelt D.
In Halobacterium salinarum, up to 18 sensory transducers (Htrs) relay environmental stimuli to an intracellular signaling system to induce tactic responses. As known from the extensively studied enterobacterial system, sensory adaptation to persisting stimulus intensities involves reversible methy ... >> More
In Halobacterium salinarum, up to 18 sensory transducers (Htrs) relay environmental stimuli to an intracellular signaling system to induce tactic responses. As known from the extensively studied enterobacterial system, sensory adaptation to persisting stimulus intensities involves reversible methylation of certain transducer glutamate residues, some of which originate from glutamine residues by deamidation. This study analyzes the in vivo deamidation and methylation of membrane-bound Htrs under physiological conditions. Electrospray ionization tandem mass spectrometry of chromatographically separated proteolytic peptides identified 19 methylation sites in 10 of the 12 predicted membrane-spanning Htrs. Matrix-assisted laser desorption/ionization mass spectrometry additionally detected three sites in two soluble Htrs. Sensory transducers contain a cytoplasmic coiled-coil region, composed of hydrophobic heptads, seven-residue repeats in which the first and the fourth residues are mostly hydrophobic. All identified Htr methylations occurred at glutamate residues at the second and/or third position of such heptads. In addition to singly methylated pairs of glutamate and/or glutamine residues, we identified singly methylated aspartate-glutamate and alanine-glutamate pairs and doubly methylated glutamate pairs. The largest methylatable regions detected in Htrs comprise six heptads along the coiled coil. One methylated glutamate residue was detected outside of such a region, in the signaling region of Htr14. Our analysis produced evidence supporting the predicted methyltransferase and methylesterase activities of halobacterial CheR and CheB, respectively. It furthermore demonstrated that CheB is required for Htr deamidations, at least at a specific glutamine-glutamate pair in Htr2 and a specific aspartate-glutamine pair in Htr4. Compared to previously reported methods, the described approach significantly facilitates the identification of physiological transducer modification sites. << Less
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Purification and characterization of the S-adenosylmethionine:glutamyl methyltransferase that modifies membrane chemoreceptor proteins in bacteria.
Simms S.A., Stock A.M., Stock J.B.
The enzyme (EC 2.1.1.24) from Salmonella typhimurium that catalyzes the S-adenosylmethionine-dependent methyl esterification of glutamyl residues in membrane chemoreceptor proteins has been purified to homogeneity, and the nucleotide sequence of the gene coding for this protein, cheR, has been det ... >> More
The enzyme (EC 2.1.1.24) from Salmonella typhimurium that catalyzes the S-adenosylmethionine-dependent methyl esterification of glutamyl residues in membrane chemoreceptor proteins has been purified to homogeneity, and the nucleotide sequence of the gene coding for this protein, cheR, has been determined. The molecular weight, amino acid composition, and N-terminal amino acid sequence of the purified protein correspond to the values predicted from the sequence of the gene. The pure protein is a 33-kDa monomer. Kinetic studies indicate that, at levels of receptor and S-adenosylmethionine present in wild type cells, the transferase is nearly saturated. The enzyme has a relatively low turnover number, approximately 10 mol of methylester formed per mol of enzyme per min; and there appear to be only approximately 200 methyltransferase monomers per wild type cell. << Less
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Crystal structure of the chemotaxis receptor methyltransferase CheR suggests a conserved structural motif for binding S-adenosylmethionine.
Djordjevic S., Stock A.M.
<h4>Background</h4>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 do ... >> More
<h4>Background</h4>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.<h4>Results</h4>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.<h4>Conclusions</h4>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. << Less