RNA—Protein Interactions in the Ribosome

Abstract

INTRODUCTION
Specific interactions between ribosomal proteins and ribosomal RNAs are essential to the assembly and stability of ribosomal particles. In Escherichia coli, approximately 20 of the 54 proteins found in the 30S and 50S subunits are able to bind individually to one or another of the three rRNAs. Many of these interactions are believed to occur early in subunit assembly and to underlie the ability of the ribosome to attain its active structure. For convenience, the class of ribosomal proteins capable of associating independently with rRNA will be referred to as RNA-binding proteins. This qualification should not be interpreted to exclude the possibility that the other proteins bind to rRNA, however, for it is likely that many of the proteins incorporated later in the assembly sequence are guided and fixed to their proper locations in the subunit structure by specific RNA-protein interactions as well. Although such interactions may therefore be direct, they are not independent in the sense that they cannot be detected in the absence of other ribosomal proteins.

In the following sections, the conditions that promote the formation and maintenance of specific ribosomal RNA–ribosomal protein complexes will be considered in relation to the structure and conformation of both RNA and protein. The discussion will focus upon components of the E. coli ribosome, which have been extensively characterized. Six or seven 30S subunit proteins from that organism bind specifically to 16S RNA; ten or eleven 50S subunit proteins bind specifically to 23S RNA, and three others independently interact...