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Rapid Isolation of the Mitoribosome from HEK Cells
Published on: October 4, 2018
The human mitochondrial tRNAMet: structure/function relationship of a unique modification in the decoding of
Yann Bilbille1, Estella M Gustilo, Kimberly A Harris
1Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA.
Journal of Molecular Biology
|December 21, 2010
Summary
Human mitochondria use a special tRNA modification, 5-formylcytidine (f(5)C), to decode multiple codons, including AUG and AUA, for methionine. This modification expands codon recognition for mitochondrial translation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Human mitochondrial mRNAs use AUG and AUA codons for methionine.
- Mitochondria employ a single tRNA, hmtRNA(Met)(CAU), to read both AUG and AUA codons.
- This tRNA features a unique modification, 5-formylcytidine (f(5)C), at position 34.
Purpose of the Study:
- To elucidate the structural and functional role of the f(5)C(34) modification in human mitochondrial tRNA.
- To understand how f(5)C(34) facilitates the decoding of non-canonical codons in human mitochondria.
Main Methods:
- NMR-restrained molecular modeling to determine the structure of the tRNA anticodon stem and loop (hmtASL(Met)(CAU)).
- Codon binding studies using Escherichia coli and bovine mitochondrial ribosomes.
Main Results:
- The f(5)C(34) modification restricts conformational dynamics of the anticodon loop, facilitating AUA decoding at both P- and A-sites.
- The modified tRNA exhibited a C-turn conformation with U-turn characteristics.
- f(5)C(34) enhanced AUA binding in the A-site and altered anticodon stem-loop binding kinetics.
- This modification also enabled P-site binding to isoleucine codons AUU and AUC.
Conclusions:
- The f(5)C(34) modification is crucial for expanding codon recognition in human mitochondria.
- It allows a single tRNA to decode AUG, AUA, AUU, and AUC codons, reassigning universal codons for mitochondrial translation.
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