Distinct eRF3 requirements suggest alternate eRF1 conformations mediate peptide release during eukaryotic translation termination.
Organisms that use the standard genetic code recognize UAA, UAG, and UGA as stop codons, whereas variant code species frequently alter this pattern of stop codon recognition. We previously demonstrated that a hybrid eRF1 carrying the Euplotes octocarinatus domain 1 fused to Saccharomyces cerevisiae domains 2 and 3 (Eo/Sc eRF1) recognized UAA and UAG, but not UGA, as stop codons. In the current study, we identified mutations in Eo/Sc eRF1 that restore UGA recognition and define distinct roles for the TASNIKS and YxCxxxF motifs in eRF1 function. Mutations in or near the YxCxxxF motif support the cavity model for stop codon recognition by eRF1. Mutations in the TASNIKS motif eliminated the eRF3 requirement for peptide release at UAA and UAG codons, but not UGA codons. These results suggest that the TASNIKS motif and eRF3 function together to trigger eRF1 conformational changes that couple stop codon recognition and peptide release during eukaryotic translation termination.
Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Hua
H
Fan-Minogue
Ming
M
Du
Andrey V
AV
Pisarev
Adam K
AK
Kallmeyer
Joe
J
Salas-Marco
Kim M
KM
Keeling
Sunnie R
SR
Thompson
Tatyana V
TV
Pestova
David M
DM
Bedwell
D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D018388:Codon, Terminator / Q000235:genetics; D016812:Euplotes / Q000235:genetics; D008954:Models, Biological; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D013489:Suppression, Genetic
D018388:Codon, Terminator; D010454:Peptide Termination Factors; D010455:Peptides; D011993:Recombinant Fusion Proteins