期刊
NUCLEIC ACIDS RESEARCH
卷 43, 期 18, 页码 9028-9038出版社
OXFORD UNIV PRESS
DOI: 10.1093/nar/gkv833
关键词
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资金
- Targeted Proteins Research Program of the Ministry of Education, Culture, Sports, Science and Technology
- Japan Society for the Promotion of Science (JSPS) [20247008, 20570148]
- JSPS Research Fellowships
- JSPS Global Centers of Excellence Program (Integrative Life Science Based on the Study of Biosignaling Mechanisms)
- Grants-in-Aid for Scientific Research [20570148, 20247008] Funding Source: KAKEN
Selenocysteine (Sec), the 21st amino acid in translation, uses its specific tRNA (tRNA(Sec)) to recognize the UGA codon. The Sec-specific elongation factor SelB brings the selenocysteinyl-tRNA(Sec) (Sec-tRNA(Sec)) to the ribosome, dependent on both an inframe UGA and a Sec-insertion sequence (SECIS) in the mRNA. The bacterial SelB binds mRNA through its C-terminal region, for which crystal structures have been reported. In this study, we determined the crystal structure of the full-length SelB from the bacterium Aquifex aeolicus, in complex with a GTP analog, at 3.2-angstrom resolution. SelB consists of three EF-Tulike domains (D1-3), followed by four winged-helix domains (WHD1-4). The spacer region, connecting the N-and C-terminal halves, fixes the position of WHD1 relative to D3. The binding site for the Sec moiety of Sec-tRNA(Sec) is located on the interface between D1 and D2, where a cysteine molecule from the crystallization solution is coordinated by Arg residues, which may mimic Sec binding. The Sec-binding site is smaller and more exposed than the corresponding site of EF-Tu. Complex models of Sec-tRNA(Sec), SECIS RNA, and the 70S ribosome suggest that the unique secondary structure of tRNA(Sec) allows SelB to specifically recognize tRNA(Sec) and characteristically place it at the ribosomal A-site.
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