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Published on: April 26, 2019
Mistranslation and its control by tRNA synthetases.
1Department of Molecular Biology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. schimmel@scripps.edu
Summary
Aminoacyl tRNA synthetases are crucial for accurate protein synthesis. A specific mistranslation, serine-for-alanine, is toxic, leading to neuropathologies and requiring unique evolutionary solutions like AlaXps.
Area of Science:
- Molecular Biology
- Biochemistry
- Evolutionary Biology
Background:
- Aminoacyl tRNA synthetases (aaRSs) are essential enzymes that translate genetic information into proteins.
- These enzymes attach specific amino acids to their corresponding transfer RNAs (tRNAs) during translation.
- Mistranslation, the attachment of the wrong amino acid to a tRNA, can be detrimental to cellular function and lead to mutations.
Purpose of the Study:
- To investigate the challenge of serine-for-alanine mistranslation in protein synthesis.
- To understand the evolutionary pressures and mechanisms that prevent this specific mistranslation.
- To elucidate the structural and functional basis for the universal problem of serine-for-alanine mistranslation.
Main Methods:
- Detailed X-ray structural analysis of alanyl-tRNA synthetases (AlaRSs) and its editing domain.
- Functional assays to assess mistranslation rates and editing efficiency.
- Comparative genomics to trace the evolutionary distribution of AlaRS editing domains and AlaXps.
Main Results:
- Serine-for-alanine mistranslation poses a significant challenge due to its severe toxic effects, including neuropathologies.
- Alanyl-tRNA synthetases possess a specialized editing activity to minimize serine-for-alanine mistranslation.
- A separate, genome-encoded fragment of the AlaRS editing domain, known as AlaXp, is conserved across the Tree of Life to provide redundant protection against this mistranslation.
Conclusions:
- Serine-for-alanine mistranslation is a universally problematic process that necessitated the evolution of sophisticated cellular mechanisms for its prevention.
- The existence of AlaXps highlights the ancient and critical selective pressures to maintain translational fidelity.
- Structural and functional insights into AlaRS editing and AlaXps reveal key aspects of genetic code interpretation and evolutionary adaptation.
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