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Updated: Jul 4, 2026
03:09
Utilizing Thermal Shift Assay to Probe Substrate Binding to Selenoprotein O
Published on: August 9, 2024
[Biochemical selenocysteine synthesis and the phylogenic study]
Takaharu Mizutani1, Takashi Osaka, Toshinobu Fujiwara
1Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan. takaharu@mbr.nifty.com
Summary
Selenium (Se) is an essential trace element incorporated as selenocysteine (Sec). This study details Sec synthesis and its ancient evolutionary origins, predating the standard translation system.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Context:
- Selenium (Se) is a vital trace element, with its unique amino acid, selenocysteine (Sec), incorporated into proteins.
- Sec utilizes a specialized tRNA and the UGA codon, which it shares with a stop codon, necessitating unique translational machinery.
- The biosynthesis and incorporation mechanisms of Sec are complex and have been investigated across various life forms.
Purpose:
- To purify and characterize key enzymes involved in selenocysteine synthesis, including seryl-tRNA synthetase (SerRS), Sec synthetase (SecS), and selenophosphate synthetase (SePS).
- To detail the procedures for preparing essential components like Sec tRNA, enzymes, and radiolabeled selenium.
- To investigate the evolutionary history and phylogenetic distribution of the Sec synthesizing system.
Summary:
- The study purified Sec synthesizing enzymes and detailed methods for preparing Sec tRNA and related components.
- Selenocysteine synthetase (SecS) was found to consist of SecSalpha and SecSbeta subunits.
- The Sec synthesizing and incorporating systems are present in Monela, Animalia, and Protoctista, but absent in Plantae and Fungi.
- Protozoa and certain worms possess Sec tRNA, with Sec synthesized by specific SecS enzymes.
- Mammalian Sec tRNA recognition by SecS is length-specific, not base-specific, focusing on the aminoacyl and D-stems.
Impact:
- Provides detailed protocols for researchers studying selenium metabolism and selenoproteins.
- Clarifies the composition and function of Sec synthesizing enzymes.
- Reveals the phylogenetic distribution of the Sec system, highlighting its absence in plants and fungi.
- Offers insights into the evolutionary origins of the Sec synthesizing system, suggesting it is older than the general translation system.
- Contributes to understanding the fundamental mechanisms of protein synthesis and the incorporation of non-canonical amino acids.
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