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Structural basis for anticodon recognition by methionyl-tRNA synthetase.
Kotaro Nakanishi1, Yuri Ogiso, Takashi Nakama
1Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.
Nature Structural & Molecular Biology
|September 13, 2005
Summary
Methionyl-tRNA synthetase (MetRS) uses a unique triple-base stack in its tRNA anticodon loop for specific recognition. This structural insight clarifies how MetRS distinguishes the correct tRNA(Met) molecule.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Methionyl-tRNA synthetase (MetRS) is crucial for initiating protein synthesis by charging tRNA(Met) with methionine.
- Specific recognition of tRNA(Met) by MetRS is essential for translational fidelity.
- Previous structural data lacked a complete understanding of the MetRS-tRNA(Met) interaction mechanism.
Purpose of the Study:
- To elucidate the structural basis of specific tRNA(Met) recognition by methionyl-tRNA synthetase (MetRS).
- To provide atomic-level details of the complex between MetRS, tRNA(Met), and a methionyl-adenylate analog.
Main Methods:
- X-ray crystallography at 2.7-A resolution.
- Analysis of the complex structure of methionyl-tRNA synthetase (MetRS) with tRNA(Met) and a methionyl-adenylate analog.
Main Results:
- The crystal structure reveals a distorted tRNA(Met) anticodon loop forming a triple-base stack (C34, A35, A38).
- A tryptophan residue extends this triple-base stack by stacking on C34.
- Specific Watson-Crick-type hydrogen bonds are formed between C34 of the tRNA and Arg357 of MetRS.
Conclusions:
- The observed structural features, including the triple-base stack and specific hydrogen bonding, explain the high specificity of MetRS for tRNA(Met).
- This detailed structure provides a definitive answer to how MetRS distinguishes tRNA(Met) from other tRNAs.