mRNA-binding site of ribosomes at different stages of translation. II. Affinity modification of Escherichia coli ribosomes bya benzylidene derivative of AUGU6 in pre- and post-translation complexes

Affinity labeling of E. coli ribosomes with the 2',3'-O-4-(N-2-chloroethyl)-N-methyl-amino]benzylidene derivative of AUGU6 (AUGU6-14C]CHRCl) was studied within the pretranslocational complex ribosome.AUGU614C]CHRCl.tRNA(fMet)(P-site).fMetPhe-tR NA(Phe)(A-site) and posttranslocational complex ribosome.AUGU614C]CHRCl.fMetPhe-tRNA(Phe)(P-site). Both 30S and 50S subunits were labeled within these complexes, but the extent of 30S subunit modification was 6-8-fold higher than those for 50S subunit. Ribosomal proteins of both subunits were found to be labeled preferentially. Proteins S1, S5, S11, L1 were identified to be crosslinked with AUGU614C]CHRCl within the pretranslocational complex and S7--within the posttranslocational complex from the data of two-dimensional electrophoresis in the polyacrylamide gel.