Specific ribosomal RNA recognition by a fragment of E. coli ribosomal protein S4 missing the C-terminal 36 amino acid residues.

We have previously investigated the role of the N-terminal region of ribosomal protein S4 to participate in 30S ribosome assembly and function (1-3). In this report we extend these studies to the two fragments produced by the chemical cleavage of protein S4 at the tryptophan residue 167. We find that the carboxyl terminal fragment (168-203) does not bind 16S RNA nor does it participate in assembly with the other 20 proteins from the 30S ribosome. In contrast, the larger fragment (1-167), does bind 16S RNA specifically. If the S4-fragment (1-167) is used to replace protein S4 in the complete 30S assembly reaction, all 20 of the other 30S proteins are incorporated. We conclude that the carboxyl terminal section of the protein S4 is not directly involved in binding 16S RNA or in the assembly of any of the other 30S proteins.