In vitro assembly of 30S ribosomal particles from precursor 16S RNA of Escherichia coli

THE concept of self-assembly has been shown to apply to the assembly of the Escherichia coli 30S ribosome in vitro by Nomura and his co-workers1,2. The reconstitution of functional 30S ribosomes from purified mature 16S RNA (m16 RNA in the nomenclature of Hecht and Woese3) and total 30S proteins has been studied in detail. The macromolecular information necessary for this in vitro assembly clearly resides in the component parts with no requirements for enzymes or cellular structures (such as membranes) which are not ultimately part of the 30S ribosome. The reconstitution system developed by Traub and Nomura1 has been useful in a variety of studies which have greatly aided our understanding of ribosome assembly, structure, and function. The biosynthesis of ribosomes, however, is known to differ in several ways from this in vitro reconstitution. The in vivo process is composed of a series of cooperative and sequential interactions between the primary ribosomal UNA transcripts and of ribosomal proteins, as well as the modification of both RNA and protein4,5.