Multiple crosslinks of proteins S7 and S9 to domains 3 and 4 of 16S ribosomal RNA in the Escherichia coli 30S particle

Abstract
RNA‐protein cross‐links were introduced into Escherichia coli 30S subunits by treatment with 1‐ethyl‐3(3‐dimethylaminopropyl)carbodiimide. 16S rRNA, cross‐linked to 30S ribosomal proteins, was isolated and hybridized with seven single‐stranded bacteriophage M13‐DNA probes. These probes, each carrying an inserted rDNA fragment, were used to select contiguous RNA sections covering domains 3 and 4 (starting at nucleotide 868 and ending at the 3′OH terminus) of the 16S rRNA. The proteins covalently linked to each selected RNA section were identified by two‐dimensional polyacrylamide gel electrophoresis. Proteins S7 and S9 were shown to be efficiently cross‐linked to multiple sites belonging to both domains.