Methionine--tRNA ligase
Methionine-tRNA ligase is an alpha 2 dimer which is required not only for elongation of protein synthesis but also for the initiation of all mRNA translation through initiator tRNA(fMet) aminoacylation.
This entry represents type 2a methionine-tRNA synthetase from eubacteria which links one zinc ion.
Reference Protein and Structure
- Sequence
-
P23395
(6.1.1.10)
(Sequence Homologues)
(PDB Homologues)
- Biological species
-
Thermus thermophilus HB8 (Bacteria)
- PDB
-
1a8h
- METHIONYL-TRNA SYNTHETASE FROM THERMUS THERMOPHILUS
(2.0 Å)
- Catalytic CATH Domains
-
2.170.220.10
3.40.50.620
(see all for 1a8h)
- Cofactors
- Zinc(2+) (1), Magnesium(2+) (1)
Enzyme Reaction (EC:6.1.1.10)
+
+
→
+
+
+
Alternative enzyme names: MetRS, Methionine translase, Methionyl-tRNA synthetase, Methionyl-transfer RNA synthetase, Methionyl-transfer ribonucleate synthetase, Methionyl-transfer ribonucleic acid synthetase,
Enzyme Mechanism
Introduction
The catalytic reaction of MetRS is divided into two steps. In the first step, methionine is activated through linkage to ATP by the formation of an anhydride bond between the methionine carboxylate and the α-phosphate of the AMP molecule. In step two, methionine is transferred from the aminoacyl adenylate to the 3′-end of its cognate tRNA molecule.
Catalytic Residues Roles
| UniProt | PDB* (1a8h) | ||
| His19, His22, Lys297, Lys300 | His19A, His22A, Lys297A, Lys300A | Binds and activates the beta-phosphate of ATP. | activator, electrostatic stabiliser |
| His147, Cys127, Cys130, Cys144 | His147A, Cys127A, Cys130A, Cys144A | Forms the Zn binding site. | metal ligand |
*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
- Larson ET et al. (2011), Biochimie, 93, 570-582. Structure of Leishmania major methionyl-tRNA synthetase in complex with intermediate products methionyladenylate and pyrophosphate. DOI:10.1016/j.biochi.2010.11.015. PMID:21144880.
- Ingvarsson H et al. (2009), Acta Crystallogr Sect F Struct Biol Cryst Commun, 65, 618-620. Crystallization ofMycobacterium smegmatismethionyl-tRNA synthetase in the presence of methionine and adenosine. DOI:10.1107/s1744309109016704. PMID:19478446.
- Crepin T et al. (2002), Biochemistry, 41, 13003-13011. Structure and Function of the C-Terminal Domain of Methionyl-tRNA Synthetase†. DOI:10.1021/bi026343m. PMID:12390027.
- Sugiura I et al. (2000), Structure, 8, 197-208. The 2.0 A crystal structure of Thermus thermophilus methionyl-tRNA synthetase reveals two RNA-binding modules. PMID:10673435.
- Fourmy D et al. (1995), Biochemistry, 34, 15681-15688. Crucial role of an idiosyncratic insertion in the Rossman fold of class 1 aminoacyl-tRNA synthetases: the case of methionyl-tRNA synthetase. DOI:10.1021/bi00048a012.
- Xu B et al. (1993), J Biol Chem, 268, 16259-16264. Identification of the metal ligands and characterization of a putative zinc finger in methionyl-tRNA synthetase. PMID:8344912.
Catalytic Residues Roles
| Residue | Roles |
|---|---|
| His19A | electrostatic stabiliser |
| His22A | electrostatic stabiliser |
| Lys297A | electrostatic stabiliser |
| Lys300A | electrostatic stabiliser |
| His19A | activator |
| His22A | activator |
| Lys297A | activator |
| Lys300A | activator |
| Cys127A | metal ligand |
| Cys130A | metal ligand |
| Cys144A | metal ligand |
| His147A | metal ligand |