Ribosomal proteins S7 and L1 are located close to the decoding site of E. coli ribosome--affinity labeling studies with modified tRNAs carrying photoreactive probes attached adjacent to the 3'-end of the anticodon.
Two photoreactive azidonitrophenyl probes have been attached to Yeast methionine elongator tRNA by chemical modification of the N6-(threoninocarbonyl)adenosine located next to the 3'-end of the anticodon. The maximum distance between the purine ring and the azido group estimated for the two probes is 16-17 and 23-24A, respectively. Binding and cross-linking of the uncharged, modified tRNAs to E. coli ribosomes have been studied with and without poly(A,U,G) as a message, under conditions directing uncharged tRNAs preferentially to the P-site. The modified tRNAs retain their binding activity and upon irradiation bind covalently to the ribosome with very high yields. Protein S7 is the major cross-linking target for both modified tRNAs, in the presence or absence of poly(A,U,G). Protein L1 and to a lesser extent proteins L33 and L27 have been found to be cross-linked with the short probe. Cross-linking to 168 rRNA reaches significant levels only in the absence of the message.
Podkowiński
J
J
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań.
Górnicki
P
P
D000345:Affinity Labels; D000926:Anticodon; D001386:Azides; D001426:Bacterial Proteins / Q000235:genetics*; D003432:Cross-Linking Reagents; D004926:Escherichia coli / Q000378:metabolism*; D008968:Molecular Conformation; D012343:RNA, Transfer; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D012358:RNA, Transfer, Met / Q000235:genetics*; D012269:Ribosomal Proteins / Q000235:genetics*; D012270:Ribosomes / Q000378:metabolism*
D000345:Affinity Labels; D000926:Anticodon; D001386:Azides; D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D012345:RNA, Transfer, Amino Acid-Specific; D012358:RNA, Transfer, Met; D012269:Ribosomal Proteins; C028546:ribosomal protein L1; C037442:ribosomal protein S7; D012343:RNA, Transfer