Structural alteration of rRNA in the L7/L12 region of 50S ribosome on removal of L7/L12 proteins

Abstract

Core particles of 50S ribosomes depleted of L7/L12 proteins are degraded by RNase I at a considerably slower rate than intact 50S ribosomes. The normal rate is restored on incorporating L7/L12 proteins into the core particles. The capacity of the core particles to inhibit the RNase I-catalyzed hydrolysis of poly A and to bind ethidium bromide is also greater with core particles than with intact 50S ribosomes. It appears from these results that the region(s) of rRNA in the vicinity of L7/L12 proteins has less ordered structure which, on removal of L7/L12 proteins, becomes more organized. Apparently, binding of L7/L12 proteins to the 50S core leads to the destabilization of double-stranded regions of rRNA.