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Publication Abstract from PubMed

Selenocysteine is the only proteinogenic amino acid encoded by a recoded in-frame UGA codon that does not operate as the canonical opal stop codon. A specialized translation elongation factor, eEFSec in eukaryotes and SelB in prokaryotes, promotes selenocysteine incorporation into selenoproteins by a still poorly understood mechanism. Our structural and biochemical results reveal that four domains of human eEFSec fold into a chalice-like structure that has similar binding affinities for GDP, GTP and other guanine nucleotides. Surprisingly, unlike in eEF1A and EF-Tu, the guanine nucleotide exchange does not cause a major conformational change in domain 1 of eEFSec, but instead induces a swing of domain 4. We propose that eEFSec employs a non-canonical mechanism involving the distinct C-terminal domain 4 for the release of the selenocysteinyl-tRNA during decoding on the ribosome.

Crystal structures of the human elongation factor eEFSec suggest a non-canonical mechanism for selenocysteine incorporation.,Dobosz-Bartoszek M, Pinkerton MH, Otwinowski Z, Chakravarthy S, Soll D, Copeland PR, Simonovic M Nat Commun. 2016 Oct 6;7:12941. doi: 10.1038/ncomms12941. PMID:27708257^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.