title: Consequences of a specific cleavage in situ of 16-S ribosomal RNA for polypeptide chain initiation.
abstract: The effect of bacteriocin (cloacin DF13) treatment of Escherichia coli ribosomes on initiation of protein synthesis has been studied in detail. In agreement with our previous findings [Baan et al. (1976) Proc. Natl Acad. Sci. U.S.A. 73, 702--706] it is shown that 70-S initiation complexes can be formed with cloacin-treated ribosomes, but that the initiation factor IF-1 does not function properly. The following pleiotropic effects of this factor have been studied: (a) the acceleration of ribosomal subunit exchange with 70-S couples; (b) the stimulation of the IF-3-mediated dissociation of 70-S ribosomes; (c) the stimulation of 30-S initiation complex formation; (d) the enhancement of the rate of release of IF-2 from 70-S initiation complexes. The effects (a) and (b) are virtually abolished after cleavage of 16-S rRNA. The effect (d) is only partially reduced whereas effect (c) seems to be unimpaired. It is concluded that 70-S initiation complex formation with cloacin-treated ribosomes suffers from improper functioning of IF-1 in the generation of active subunits from 70-S tight couples. This is the only effect on initiation. It can be compensated for by adding more IF-3. The data provide functional evidence that 16-S rRNA is involved in ribosomal subunit interaction.
mesh_terms: D001430:Bacteriocins / Q000494:pharmacology*; D004754:Enterobacter; D004926:Escherichia coli; D010442:Peptide Chain Initiation, Translational / Q000187:drug effects*; D010448:Peptide Initiation Factors; D012335:RNA, Ribosomal / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D001430:Bacteriocins; D010448:Peptide Initiation Factors; D012335:RNA, Ribosomal; D012346:RNA, Transfer, Amino Acyl