TY - JOUR
T1 - Crystal structures of the human elongation factor eEFSec suggest a non-canonical mechanism for selenocysteine incorporation
AU - Dobosz-Bartoszek, Malgorzata
AU - Pinkerton, Mark H.
AU - Otwinowski, Zbyszek
AU - Chakravarthy, Srinivas
AU - Söll, Dieter
AU - Copeland, Paul R.
AU - Simonovic, Miljan
N1 - Funding Information:
We thank the staff of LS-CAT (21-ID) and SBC-CAT (19-ID) beamlines at the Advanced Photon Source (APS) of the Argonne National Laboratory (ANL) and organizers of the 7th Annual CCP4 USA Crystallography School for their help during X-ray data collection and processing, the staff at the Advanced Protein Characterization Facility (SBC-CAT, APS) for access to Mosquito crystallization robots and the staff of BioCAT (18-ID) beamline for help during SAXS data collection. We are grateful to Yury Polikanov for comments, suggestions and critical reading of the manuscript. The initial part of the study was supported by the University of Illinois at Chicago startup fund and a grant from the American Cancer Society, Illinois Division (225752 to M.S.). The subsequent studies were supported by grants from the National Institute of General Medical Sciences (GM097042 to M.S., GM070773 to P.R.C. and GM22854 to D.S.). This research used resources of the APS, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by ANL under contract no. DE-AC02-06CH11357. Use of the LS-CAT Sector 21 was supported by the Michigan Economic Development Corporation and the Michigan Technology Tri-Corridor (grant 085P1000817). BioCAT is supported by grant from the National Institute of General Medical Sciences of the National Institutes of Health (P41 GM103622). Use of the Pilatus 3 1M detector was provided by grant 1S10D018090-01 from the National Institute of General Medical Sciences.
Publisher Copyright:
© The Author(s) 2016.
PY - 2016/10/6
Y1 - 2016/10/6
N2 - 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.
AB - 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.
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U2 - 10.1038/ncomms12941
DO - 10.1038/ncomms12941
M3 - Article
C2 - 27708257
AN - SCOPUS:84990836946
SN - 2041-1723
VL - 7
JO - Nature communications
JF - Nature communications
M1 - 12941
ER -