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Human Thg1 displays tRNA-inducible GTPase activity
Titi Rindi Antika1, Kun Rohmatan Nazilah1, Yi-Hsueh Lee1
1Department of Life Sciences, National Central University, Zhongli District, Taoyuan 320317, Taiwan.
Nucleic Acids Research
|September 15, 2022
Summary
Human tRNAHis guanylyltransferase 1 (HsThg1) adds a unique guanosine to mitochondrial tRNAHis. HsThg1 uses GTPase activity to prevent multiple guanosine additions, ensuring accurate tRNAHis maturation.
Area of Science:
- Biochemistry
- Molecular Biology
- RNA Biology
Background:
- tRNAHis guanylyltransferase (Thg1) enzymes are essential for tRNAHis maturation.
- The unique G-1 modification is critical for histidyl-tRNA synthetase recognition.
- Human Thg1 (HsThg1) exhibits dual specificity for cytoplasmic and mitochondrial tRNAHis.
Purpose of the Study:
- To elucidate the mechanism by which HsThg1 prevents multiple guanosine additions to mitochondrial tRNAHis (tRNAmHis).
- To investigate the role of ATP and GTP in HsThg1 activity.
- To characterize the novel GTPase activity of HsThg1.
Main Methods:
- In vitro enzymatic assays using purified HsThg1 and tRNAmHis.
- Analysis of nucleotide incorporation using varying ATP and GTP concentrations.
- Characterization of HsThg1's GTPase activity and its regulation.
Main Results:
- Mature human tRNAmHis contains only a single G-1 modification.
- ATP is essential for G-1 addition to tRNAmHis by HsThg1.
- HsThg1 exhibits tRNA-inducible GTPase activity, which is inhibited by ATP, preventing multiple GTP incorporation.
Conclusions:
- HsThg1 precisely controls guanosine incorporation into tRNAmHis, adding only G-1.
- HsThg1's GTPase activity acts as a regulatory mechanism to prevent over-modification.
- This regulation is crucial for maintaining the fidelity of mitochondrial protein synthesis.
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