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03:09
Utilizing Thermal Shift Assay to Probe Substrate Binding to Selenoprotein O
Published on: August 9, 2024
New developments in selenium biochemistry: selenocysteine biosynthesis in eukaryotes and archaea
Xue-Ming Xu1, Bradley A Carlson, Yan Zhang
1Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Institutes of Health, Bethesda, MD 20892, USA.
Biological Trace Element Research
|October 6, 2007
Summary
Eukaryotes and archaea utilize a novel enzyme, O-phosphoseryl-tRNA kinase (PSTK), and selenocysteine synthase (SecS) for selenocysteine insertion. This pathway is conserved across species containing selenoproteins.
Area of Science:
- Biochemistry
- Molecular Biology
- Genomics
Background:
- Selenocysteine (Sec) is the 21st amino acid, incorporated via a unique co-translational mechanism.
- Understanding the biosynthesis pathway of Sec is crucial for comprehending selenoprotein function.
Purpose of the Study:
- To elucidate the enzymatic machinery and substrates involved in selenocysteine biosynthesis in eukaryotes and archaea.
- To identify the specific enzymes responsible for key steps in the Sec insertion pathway.
Main Methods:
- Comparative genomics and experimental analyses were employed.
- Enzyme activity assays and substrate identification were performed.
Main Results:
- O-phosphoseryl-tRNA [Ser]Sec kinase (PSTK) was identified as essential for phosphorylating seryl-tRNA [Ser]Sec.
- Mammalian selenocysteine synthase (SecS) was identified as the soluble liver antigen (SLA), utilizing O-phosphoseryl-tRNA[Ser]Sec and selenophosphate.
- Selenophosphate synthetase 2 (SPS2) was confirmed as the enzyme synthesizing the active selenium donor, monoselenophosphate.
Conclusions:
- A conserved pathway for Sec biosynthesis involving PSTK and SecS exists in eukaryotes and archaea.
- Monoselenophosphate is the direct selenium donor in this pathway.
- The identified pathway provides a comprehensive understanding of Sec incorporation into selenoproteins.
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