Identification of a 16-S RNA fragment crosslinked to protein S1 within Escherichia coli ribosomal 30-S subunits by the use of a crosslinking reagent: ethyl 4-azidobenzoylaminoacetimidate.

The bifunctional reagent ethyl 4-azidobenzoylaminoacetimidate was used to crosslink specifically ribosomal protein S1 to 16-S RNA within 30-S subunits. The reagent was attached to isolated protein S1. The modified protein was reassociated with protein-S1-depleted 30-S subunits and then crosslinked to the RNA molecule. The covalently bound 16-S RNA-protein S1 complex was isolated and the RNA fragment C-U-A-A-C-G-C-G-U-U-A-A-G-U-C-G-A-C-C-G-C-C-U-G-G-G-G-A-G (positions 861-889) was characterized to be crosslinked to protein S1.