Puromycin reaction of the A-site bound peptidyl-tRNA.
AcPhe2-tRNA(Phe) which appears in ribosomes after consecutive binding of AcPhe-tRNA(Phe) at the P sites and EF-Tu-directed binding of Phe-tRNA(Phe) at the A sites is able to react quantitatively with puromycin in the absence of EF-G. One could readily explain this fact to be the consequence of spontaneous translocation. However, a detailed study of kinetics of puromycin reaction carried out with the use of viomycin (inhibitor of translocation) and the P-site test revealed that, apart from spontaneous translocation, this peptidyl-tRNA could react with puromycin being located at the A site. This leads to the conclusion that the transpeptidation reaction triggers conformational changes in the A-site ribosomal complex bringing the 3'-end of a newly synthesized peptidyl-tRNA nearer to the peptidyl site of peptidyltransferase center. This is detected functionally as a highly pronounced ability of such a peptidyl-tRNA to react with puromycin.
Semenkov
Y P
YP
BP Konstantinov Nuclear Physics Institute, Russian Academy of Sciences, Gatchina, Leningrad Region.
Shapkina
T G
TG
Kirillov
S V
SV
D001665:Binding Sites; D007700:Kinetics; D011691:Puromycin / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D014756:Viomycin / Q000378:metabolism
D012346:RNA, Transfer, Amino Acyl; C006383:tRNA, N-acetylphenylalanine-; D011691:Puromycin; D014756:Viomycin