title: Location of 5.8 S rRNA contact sites in 28 S rRNA and the effect of alpha-sarcin on the association of 5.8 S rRNA with 28 S rRNA.
abstract: We have constructed phage M13mp7 clones each containing the coding strand from one of three restriction fragments which collectively span the mouse 28 S rRNA gene with the exception of the 3'-terminal approximately 500 base pairs. When hybridized to 28 S rRNA, only the fragment containing the 5'-terminal 1400 nucleotides of the gene inhibited the annealing of 5.8 S rRNA to the 28 S rRNA. The same results were obtained when either the 5'- or 3'-terminal fragment of 5.8 S rRNA was used in lieu of intact 5.8 S rRNA, each of which had been shown to contain an independent 28 S rRNA contact site. However, alpha-sarcin, a cytotoxin that inhibits protein synthesis by hydrolyzing a phosphodiester bond near the 3' end of 28 S rRNA, produces a 3'-terminal 488-nucleotide fragment which exhibits a marginal capacity to anneal to 5.8 S rRNA. These results indicate that 5.8 S rRNA interacts predominantly with a structural domain near the 5' end of 28 S rRNA. This conclusion is consistent with base-pairing interactions between 5.8 S rRNA and 28 S rRNA based on the proposed secondary structures for Escherichia coli 23 S and yeast 26 S rRNAs. However, alpha-sarcin treatment of ribosomes affects the stability of the binding of 5.8 S rRNA to the 28 S rRNA, even though the toxin hydrolyzes a phosphodiester bond several thousand nucleotides from the proposed contact regions. Finally, mouse 5.8 S rRNA was shown to lack two internal nucleotides reported to be present in rat 5.8 S rRNA.
mesh_terms: D000818:Animals; D001230:Aspergillus; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004722:Endoribonucleases; D005347:Fibroblasts / Q000378:metabolism; D005656:Fungal Proteins / Q000494:pharmacology*; D005796:Genes; D008099:Liver / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D011132:Polyribosomes / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D051381:Rats
chemical_list: D005656:Fungal Proteins; D046911:Macromolecular Substances; D012335:RNA, Ribosomal; C014801:alpha-sarcin; D004722:Endoribonucleases; D004262:DNA Restriction Enzymes