Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2021 Dec 8;22(24):13204.
doi: 10.3390/ijms222413204.

Ribosome Fate during Decoding of UGA-Sec Codons

Paul R Copeland  1 , Michael T Howard  2
Affiliations
Review

Ribosome Fate during Decoding of UGA-Sec Codons

Paul R Copeland et al. Int J Mol Sci. .

Abstract

Decoding of genetic information into polypeptides occurs during translation, generally following the codon assignment rules of the organism's genetic code. However, recoding signals in certain mRNAs can overwrite the normal rules of translation. An exquisite example of this occurs during translation of selenoprotein mRNAs, wherein UGA codons are reassigned to encode for the 21st proteogenic amino acid, selenocysteine. In this review, we will examine what is known about the mechanisms of UGA recoding and discuss the fate of ribosomes that fail to incorporate selenocysteine.

Keywords: SECIS; SECIS-binding protein; nonsense-mediated decay; recoding; ribosome rescue; selenocysteine; selenoprotein; translation termination.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Prokaryotic versus eukaryotic Sec insertion showing the SECIS elements and core components required for Sec-tRNASec delivery to the ribosome. (A) In prokaryotes, the SECIS element is located just downstream from the UGA codon within the coding sequence. The bulged U and G U nucleotides required for SelB binding are shown. SelB binds to the SECIS element and delivers the Sec-tRNASec to the ribosome for UGA recoding. (B) In eukaryotes, the SECIS element is located in the 3′ UTR. The SECIS-binding protein, SECISBP2 (SBP2), recruits the Sec-specific elongation factor EEFSEC (eEFSec) to deliver Sec-tRNASec to the ribosome for UGA recoding. On the right-hand side of the figure, the SECIS elements are depicted as a helix.
Figure 2
Figure 2
Possible fates of ribosomes encountering UGA-Sec codons. (A) Ribosomes failing to incorporate Sec may prematurely terminate translation, leading to nonsense-mediated decay (NMD) or NMD escape and continued translation by ribosomes located upstream of the UGA codon. (B) Sec-incorporation mediated by Sec insertion machinery. (C) Ribosomes that fail to incorporate Sec or terminate may be subject to various translational quality control pathways leading to ribosome release or recovery.
See this image and copyright information in PMC

References

    1. Atkins J.F., Gesteland R.F. Nucleic Acids and Molecular Biology. Springer; New York, NY, USA: 2010. Recoding: Expansion of decoding rules enriches gene expression.
    1. Vindry C., Ohlmann T., Chavatte L. Translation regulation of mammalian selenoproteins. Biochim. Biophys. Acta Gen. Subj. 2018;1862:2480–2492. doi: 10.1016/j.bbagen.2018.05.010. - DOI - PubMed
    1. Howard M.T., Copeland P.R. New directions for understanding the codon redefinition required for selenocysteine incorporation. Biol. Trace Elem. Res. 2019;192:18–25. doi: 10.1007/s12011-019-01827-y. - DOI - PMC - PubMed
    1. Kryukov G.V., Castellano S., Novoselov S.V., Lobanov A.V., Zehtab O., Guigo R., Gladyshev V.N. Characterization of mammalian selenoproteomes. Science. 2003;300:1439–1443. doi: 10.1126/science.1083516. - DOI - PubMed
    1. Kryukov G.V., Gladyshev V.N. The prokaryotic selenoproteome. EMBO Rep. 2004;5:538–543. doi: 10.1038/sj.embor.7400126. - DOI - PMC - PubMed

LinkOut - more resources