Structure of the mammalian ribosome as it decodes the selenocysteine UGA codon
Hilal, T.; Killam, B.Y.; Grozdanovic, M.; Dobosz-Bartoszek, M.; Loerke, J.; Bürger, J.; Mielke, T.; Copeland, P.R.; Simonovic, M.; Spahn, C.M.T. (2022). Structure of the mammalian ribosome as it decodes the selenocysteine UGA codon. Science (Wash.) 376(6599): 1338-1343. https://dx.doi.org/10.1126/science.abg3875
In: Science (Washington). American Association for the Advancement of Science: New York, N.Y. ISSN 0036-8075; e-ISSN 1095-9203, more
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| Authors | | Top |
- Hilal, T.
- Killam, B.Y.
- Grozdanovic, M.
- Dobosz-Bartoszek, M.
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- Loerke, J.
- Bürger, J.
- Mielke, T.
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- Copeland, P.R.
- Simonovic, M.
- Spahn, C.M.T.
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| Abstract |
The elongation of eukaryotic selenoproteins relies on a poorly understood process of interpreting in-frame UGA stop codons as selenocysteine (Sec). We used cryo-electron microscopy to visualize Sec UGA recoding in mammals. A complex between the noncoding Sec-insertion sequence (SECIS), SECIS-binding protein 2 (SBP2), and 40S ribosomal subunit enables Sec-specific elongation factor eEFSec to deliver Sec. eEFSec and SBP2 do not interact directly but rather deploy their carboxyl-terminal domains to engage with the opposite ends of the SECIS. By using its Lys-rich and carboxyl-terminal segments, the ribosomal protein eS31 simultaneously interacts with Sec-specific transfer RNA (tRNASec) and SBP2, which further stabilizes the assembly. eEFSec is indiscriminate toward l-serine and facilitates its misincorporation at Sec UGA codons. Our results support a fundamentally distinct mechanism of Sec UGA recoding in eukaryotes from that in bacteria |
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