Binding of Aminoacyl‐tRNA to Reconstituted Subparticles of Escherichia coli Large Ribosomal Subunits

Abstract

The activity of 50‐S subunits to stimulate the binding of aminoacyl‐tRNA to the 30‐S subunits was lost when the particles were washed with LiCl concentrations higher than 1.0 M [Kazemie, M. (1975) Eur. J. Biochem. 58, 501–510]. The particles could regain this activity when they were incubated with the corresponding LiCl washes. This effect of LiCI washes was used as an assay for identification of 50‐S subunit proteins which are essential for binding of aminoacyl‐tRNA. A protein mixture containing mainly L1, L11 and L16 can reactivate 50‐S ‘core’ particles, consisting of 10, proteins and 23‐S RNA, to bind aminoacyl‐tRNAs in the presence of 30‐S subunits. Besides 5‐S RNA, protein L24 has a stimulatory effect on the binding of aminoacyl‐tRNA. Proteins L2, L20 and L23 are possibly required for maintaining the 50‐S subunits in the correct conformation for binding of aminoacyl‐tRNAs.