Evidence that proteins S1, S11 1 and S21 directly participate in the binding of transfer RNA to the 30S ribosome

Abstract

In a previous publication we reported that the tyrosine selective reagent, tetranitromethane, causes complete inactivation of E . coli 30S ribosomes for poiy U directed non-enzymatic phe-tRNA binding. This inactivation was demonstrated to be due to the chemical modification of the protein moiety of the ribosome. We have now identified the proteins of the 30S particle inactivated by this modification. Using a method of ribosome reconstitution we have found that unmodified proteins S1, Sll, and S21 are essential for the restoration of the phe-tRNA binding activity of tetranitromethane inactivated ribosomes. We propose that these three proteins are intimately involved in the 30S ribosome binding site for tRNA.