The integrity of the sarcin/ricin domain of 23 S ribosomal RNA is not required for elongation factor-independent peptide synthesis.
The elongation stage of protein synthesis consists of repeated cycles of the binding of aminoacyl-tRNA, peptide bond formation, and translocation. The process is normally catalyzed by the elongation factors Tu and G; however, the reactions can proceed, at least in prescribed and limited circumstance, in the absence of the elongation factors, a finding that strongly implies that the chemistry of protein synthesis is inherent in the ribosome. The sarcin/ricin domain in 23 S rRNA, the site of inactivation of ribosomes by ribotoxins, is where the elongation factors bind. The question that arises is whether the sarcin/ricin domain is necessary for factor-independent peptide synthesis. The answer is that it is not. The disruption of the sarcin/ricin domain by covalent modification with either sarcin or pokeweed antiviral protein did not affect factor-independent peptide synthesis; nor did lethal mutations of nucleotides that abolish the binding of elongation factors. The results imply that the sole function of the sarcin/ricin domain is to provide a binding site for the elongation factors and, hence, to facilitate the elongation reactions. The results also raise the possibility of the co-evolution of the sarcin/ricin domain and the elongation factors.
Chan
Yuen-Ling
YL
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
Wool
Ira G
IG
D001483:Base Sequence; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation / Q000187:drug effects; D010445:Peptide Elongation Factors / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012338:RNA, Ribosomal, 23S / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D012276:Ricin / Q000494:pharmacology; D014118:Toxins, Biological / Q000494:pharmacology
D010445:Peptide Elongation Factors; D011500:Protein Synthesis Inhibitors; D012338:RNA, Ribosomal, 23S; D014118:Toxins, Biological; D012276:Ricin