Abstract
RNA-protein cross-links were introduced into E. coli 30S ribosomal subunits by reaction with 2-iminothiolane followed by a mild ultraviolet irradiation treatment. After removal of non-reacted protein and partial nuclease digestion of the cross-linked 16S RNA-protein moiety, a number of individual cross-linked complexes could be isolated and the sites of attachment of the proteins to the RNA determined. Protein S8 was cross-linked to the RNA at three different positions, within oligo-nucleotides encompassing positions 629–633, 651–654, and (tentatively) 593–597 in the 16S sequence. Protein S7 was cross-linked within two oligonucleotides encompassing positions 1238–1240, and 1377–1378. In addition, a site at position 723–724 was observed, cross-linked to protein S19, S20 or S21.