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Function of the extra 5'-phosphate carried by histidine tRNA
M Fromant1, P Plateau, S Blanquet
1Laboratoire de Biochimie, Unité Mixte de Recherche No. 7654, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France.
Biochemistry
|April 5, 2000
Summary
The 5' phosphate near histidine tRNA's extra nucleotide is key for aminoacylation by histidyl-tRNA synthetase. However, peptidyl-tRNA hydrolase recognizes a different phosphate on this tRNA.
Area of Science:
- Molecular Biology
- Biochemistry
- RNA Biology
Background:
- Elongator tRNAs typically have a 5' terminal phosphate.
- Histidine tRNA (tRNA(His)) possesses an unusual extra nucleotide at position -1.
- This extra nucleotide is thought to be crucial for recognition by histidyl-tRNA synthetase.
Purpose of the Study:
- To investigate the role of the extra nucleotide and its associated phosphate in tRNA(His) recognition.
- To determine the specific recognition mechanisms employed by histidyl-tRNA synthetase and peptidyl-tRNA hydrolase.
Main Methods:
- Biochemical assays using Escherichia coli enzymes.
- Analysis of tRNA aminoacylation efficiency.
- Characterization of tRNA-enzyme interactions.
Main Results:
- The phosphate group 5' to the extra nucleotide of tRNA(His) is critical for efficient aminoacylation by histidyl-tRNA synthetase.
- This atypical 5' phosphate is not essential for peptidyl-tRNA hydrolase activity.
- Peptidyl-tRNA hydrolase recognizes the phosphate within the phosphodiester bond between positions -1 and +1 of tRNA(His).
Conclusions:
- The 5' phosphate adjacent to the -1 nucleotide is the primary determinant for histidyl-tRNA synthetase recognition and aminoacylation efficiency.
- Peptidyl-tRNA hydrolase utilizes a distinct recognition mechanism, targeting the +1 phosphate of tRNA(His), similar to its recognition of other elongator tRNAs.