title: Conformational changes in the structure of domains II and V of 28S rRNA in ribosomes treated with the translational inhibitors ricin or alpha-sarcin.
abstract: Ricin and alpha-sarcin modify neighbouring sites in the so-called sarcin/ricin (S/R) loop of 28S rRNA, thereby destroying the necessary dynamic flexibility of the ribosome, and inhibiting the elongation factor assisted steps of the elongation cycle. The effects of the two translational inhibitors on the conformation of domains II and V of 28S rRNA were investigated by chemical modification of programmed mouse ribosomes pretreated with ricin or alpha-sarcin. The results showed that the two ribosome-inactivating proteins (RIP) influenced the structure of the ribosomal RNA. Inhibitor-affected sites were located at or near sites previously proposed to be involved in functional domains. The modification patterns obtained after ricin or alpha-sarcin treatment of ribosomes were partially overlapping. However, there were several inhibitor-specific structural changes in 28S rRNA. Such changes were found at positions located at the GTPase activating centre of the ribosome and in the S/R domain, indicating that the structure in these regions of the ribosomes differed after treatment with the two inhibitors. These changes are consistent with ricin and alpha-sarcin having specific effects on eEF-2 and eEF-1 interaction with the ribosome, respectively.
authors.affiliation: Cell Biology Unit, Natural Science Section, Södertörns Högskola, Box 4101, S-141 04 Huddinge, Sweden.
authors.forename: Sofia L
authors.initials: SL
authors.lastname: Larsson
authors.forename: Marika S
authors.initials: MS
authors.lastname: Sloma
authors.forename: Odd
authors.initials: O
authors.lastname: Nygård
mesh_terms: D000818:Animals; D001483:Base Sequence; D004722:Endoribonucleases / Q000494:pharmacology*; D005656:Fungal Proteins; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012339:RNA, Ribosomal, 28S / Q000737:chemistry*; D012270:Ribosomes / Q000187:drug effects*; D012276:Ricin / Q000494:pharmacology*
chemical_list: D005656:Fungal Proteins; D011500:Protein Synthesis Inhibitors; D012339:RNA, Ribosomal, 28S; C014801:alpha-sarcin; D012276:Ricin; D004722:Endoribonucleases