Divergence of selenocysteine tRNA recognition by archaeal and eukaryotic O -phosphoseryl-tRNASec kinase
- Yale Univ., New Haven, CT (United States). Dept. of Molecular Biophysics and Biochemistry; DOE/OSTI
- Yale Univ., New Haven, CT (United States). Dept. of Molecular Biophysics and Biochemistry
- Yale Univ., New Haven, CT (United States). Dept. of Molecular Biophysics and Biochemistry; Yale Univ., New Haven, CT (United States). Dept. of Chemistry
Selenocysteine (Sec) biosynthesis in archaea and eukaryotes requires three steps: serylation of tRNASec by seryl-tRNA synthetase (SerRS), phosphorylation of Ser-tRNASec by O-phosphoseryl-tRNASec kinase (PSTK), and conversion of O-phosphoseryl-tRNASec (Sep-tRNASec) by SeptRNA:Sec-tRNA synthase (SepSecS) to SectRNASec. Although SerRS recognizes both tRNASec and tRNASer species, PSTK must discriminate SertRNASec from Ser-tRNASer. Based on a comparison of the sequences and secondary structures of archaeal tRNASec and tRNASer, we introduced mutations into Methanococcus maripaludis tRNASec to investigate how Methanocaldococcus jannaschii PSTK distinguishes tRNASec from tRNASer. Unlike eukaryotic PSTK, the archaeal enzyme was found to recognize the acceptor stem rather than the length and secondary structure of the D-stem. While the D-arm and T-loop provide minor identity elements, the acceptor stem base pairs G2-C71 and C3-G70 in tRNASec were crucial for discrimination from tRNASer. Furthermore, the A5-U68 base pair in tRNASer has some antideterminant properties for PSTK. Transplantation of these identity elements into the tRNASerUGA scaffold resulted in phosphorylation of the chimeric Ser-tRNA. The chimera was able to stimulate the ATPase activity of PSTK albeit at a lower level than tRNASec, whereas tRNASer did not. Additionally, the seryl moiety of Ser-tRNASec is not required for enzyme recognition, as PSTK efficiently phosphorylated Thr-tRNASec.
- Research Organization:
- Yale Univ., New Haven, CT (United States)
- Sponsoring Organization:
- National Institutes of Health (NIH); USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division
- OSTI ID:
- 1625437
- Journal Information:
- Nucleic Acids Research, Journal Name: Nucleic Acids Research Journal Issue: 6 Vol. 36; ISSN 0305-1048
- Publisher:
- Oxford University PressCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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