An Attempt at the Identification of the Proteins Involved in the Incorporation of 5‐S RNA during 50‐S Ribosomal Subunit Assembly

Abstract

In an attempt to determine the RNA‐protein interactions involved in the biogenesis of the 50‐S ribosomal subunit we have developed a simple and specific system in vitro which reflects some of the intricacies of the Escherichia coli 50‐S subunit. By studying the interaction of isolated ribosomal proteins with 5‐S and 23‐S RNAs we have demonstrated the formation of a stable complex which contains 5‐S RNA and 23‐S RNA and which is dependent upon only two or three ribosomal proteins. The characteristics of this complex have been determined and the responsible proteins identified. The 5‐S · 23‐S RNA complex is dependent upon protein L18 in conjunction with either L6 or L25. Although it would be premature to conclude that these results in vitro are directly related to the assembly map in vivo of the 50‐S subunit, there is a strong correlation between our results and those obtained with various natural and artificial ribosomal subparticles.