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Updated: Jul 19, 2025
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In vitro tRNA Methylation Assay with the Entamoeba histolytica DNA and tRNA Methyltransferase Dnmt2 Ehmeth Enzyme
Published on: October 19, 2010
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Restricted tRNA methylation by intermolecular disulfide bonds in DNMT2/TRDMT1
Huari Li1, Daiyun Zhu1, Yapeng Yang1
1College of Veterinary Medicine, Huazhong Agricultural University, No.1 Shizishan Street, Wuhan 430070, Hubei, China.
International Journal of Biological Macromolecules
|August 14, 2023
Summary
DNMT2/TRDMT1 enzyme activity is restricted by disulfide bonds, impacting tRNA methylation. Understanding this mechanism is crucial for redox stress-related diseases.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Biology
Background:
- DNMT2/TRDMT1 methylates tRNAs at C38, crucial for survival and homeostasis.
- DNMT2/TRDMT1 shows weaker in vitro tRNA methylation activity compared to TrmD and Trm5.
Purpose of the Study:
- To investigate the mechanism restricting DNMT2/TRDMT1's tRNA methylation activity.
- To elucidate the role of disulfide bonds in DNMT2/TRDMT1 function and regulation.
Main Methods:
- Enzyme activity assays under optimized buffer conditions (Buffer C, 37°C) with Dithiothreitol (DTT).
- Analysis of protein conformation and oligomeric formation using reductants.
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify disulfide bonds.
- Expression analysis in HEK293T cells under varying stress conditions (GSSG, GSH).
Main Results:
- Optimized conditions and DTT are essential for DNMT2/TRDMT1 activation.
- Predominant intermolecular disulfide bonds identified: C292-C292, C292-C287 in recombinant protein; C79-C24, C292-C292, C222-C24 in HEK293T cells, forming dimers.
- GSSG stress initially enhanced tRNA methylation but later became unfavorable with enzyme nuclear accumulation.
- GSH stress downregulated DNMT2/TRDMT1 expression and promoted tRNA methylation, likely by breaking disulfide bonds.
Conclusions:
- Disulfide bonds restrict DNMT2/TRDMT1 tRNA methylation activity.
- Findings provide insights into redox stress regulation of tRNA methylation.
- Implications for understanding and treating redox stress-related diseases.
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