44] Protein-RNA interactions in the bacterial ribosome

Abstract

The chapter discusses the protein-RNA interactions in the bacterial ribosomes. The assembly, function, and stability of the ribosome are all assured by a complex network of specific associations among its protein and RNA constituents. Over one-third of the 50 to 55 ribosomal proteins from Escherichia coli have been shown to bind directly and independently to homologous 16 S, 23 S, and 5 S RNAs. These interactions play a major role in the early phases of 30 S and 50 S subunit assembly by initiating the formation of a series of protein nuclei within localized, and relatively antonomous, segments of the RNA. The importance of direct protein-RNA interaction in ribosome reconstitution was clearly delineated by the derivation of an assembly map for the E. coli 30 S subunit which showed that the binding of a small group of proteins to the 16 S RNA was a prerequisite for subsequent assembly reactions. The chapter provides an overview of techniques currently used in the study of interactions among protein and RNA constituents of bacterial ribosomes. Procedures for the formation, identification, and enzymic fragmentation of ribonucleoprotein complexes are also described. The application of several specialized techniques, both conventional and novel, to ribosomal protein—RNA association are surveyed, with particular attention to the kinds of information they provide.