Role of the individual domains of translation termination factor eRF1 in GTP binding to eRF3.
Eukaryotic translational termination is triggered by polypeptide release factors eRF1, eRF3, and one of the three stop codons at the ribosomal A-site. Isothermal titration calorimetry shows that (i) the separated MC, M, and C domains of human eRF1 bind to eRF3; (ii) GTP binding to eRF3 requires complex formation with either the MC or M + C domains; (iii) the M domain interacts with the N and C domains; (iv) the MC domain and Mg2+ induce GTPase activity of eRF3 in the ribosome. We suggest that GDP binding site of eRF3 acquires an ability to bind gamma-phosphate of GTP if altered by cooperative action of the M and C domains of eRF1. Thus, the stop-codon decoding is associated with the N domain of eRF1 while the GTPase activity of eRF3 is controlled by the MC domain of eRF1 demonstrating a substantial structural uncoupling of these two activities though functionally they are interrelated.
Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, Moscow 119991, Russia.
Artem V
AV
Kononenko
Vladimir A
VA
Mitkevich
Vera I
VI
Dubovaya
Peter M
PM
Kolosov
Alexander A
AA
Makarov
Lev L
LL
Kisselev
D002151:Calorimetry; D018388:Codon, Terminator; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000378:metabolism*; D013816:Thermodynamics
D018388:Codon, Terminator; C489002:ETF1 protein, human; D010454:Peptide Termination Factors; C087971:peptide-chain-release factor 3; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases