Different conformations of tRNA in the ribosomal P-site and A-site.
Footprinting studies involving radioactively end-labelled tRNA species bound at either the ribosomal P- or A-site have yielded information that the tRNA's conformation is different in the two sites. Appropriate controls showed the relevance of using poly(U)-directed tRNAPhe binding in the P-site and Phe-tRNAPhe in the A-site. Digestion of the tRNA species was effected by RNases T1, T2 and cobra venom RNase. Experiments were performed with tRNAs 32P-labelled at either end to establish positions of primary cuts more confidently. In addition to the common protection of the aminoacyl-stem and anticodon-arm, footprinting experiments revealed striking differences in the accessibility of the T- and D-loops of tRNAs bound in the P- and A-sites. We observed a more open structure for the tRNA in the A-site. These results are consistent with a dynamic structure of tRNA during the translocation step of protein biosynthesis.
T
T
Jørgensen
G E
GE
Siboska
F P
FP
Wikman
B F
BF
Clark
D001665:Binding Sites; D004586:Electrophoresis / Q000379:methods; D004926:Escherichia coli / Q000235:genetics; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012343:RNA, Transfer; D012346:RNA, Transfer, Amino Acyl; D012260:Ribonucleases
D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012346:RNA, Transfer, Amino Acyl; D012343:RNA, Transfer; D012260:Ribonucleases