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Metabolic Labeling and Profiling of Transfer RNAs Using Macroarrays
Published on: January 16, 2018
Structural elements that contribute to an unusual tertiary interaction in a transfer RNA
1Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Biochemistry
|April 19, 1994
Summary
Structural variations in transfer RNA (tRNA) interactions, like the G15.G48 pair in E. coli tRNA(Cys), impact cysteine aminoacylation efficiency. Modifying D loop nucleotides can revert unusual pairs to a standard Levitt-like interaction.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Transfer RNAs (tRNAs) possess conserved tertiary hydrogen bonds crucial for their structure and function.
- The stabilization mechanisms underlying these tertiary interactions remain incompletely understood.
- Escherichia coli tRNA(Cys) exhibits a unique G15.G48 tertiary interaction, differing from the canonical Levitt base pair found in other tRNAs.
Purpose of the Study:
- To investigate the structural elements responsible for the G15.G48 tertiary interaction variation in E. coli tRNA(Cys).
- To understand how structural changes influence the G15.G48 interaction and its role in cysteine aminoacylation.
Main Methods:
- Utilized chemical probing to analyze nucleotide interactions within tRNA(Cys).
- Introduced specific nucleotide substitutions (U21 to A21) and structural alterations (13:22 Watson-Crick base pair) in the D stem.
- Assessed the impact of these modifications on the G15.G48 tertiary interaction and aminoacylation efficiency.
Main Results:
- Substitution of U21 with A21 and formation of a D stem Watson-Crick pair (13:22) shifted the G15.G48 interaction towards a Levitt-like base pair.
- This structural switch significantly reduced the catalytic efficiency of cysteine aminoacylation by two orders of magnitude.
- Modifications involving insertions in the D or variable loops showed minimal impact on the G15.G48 interaction.
Conclusions:
- Specific nucleotide identities and base pairing in the D stem are critical for establishing the canonical Levitt-like G15.G48 tertiary interaction.
- The G15.G48 tertiary interaction's deviation from the Levitt base pair is a key determinant of E. coli tRNA(Cys) aminoacylation efficiency.
- Structural plasticity in tRNA loops influences tertiary interactions and their functional consequences.
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