The central part of the 5.8 S rRNA is differently arranged in programmed and free human ribosomes.
A sequence-specific modification of the human 5.8 S rRNA in isolated 60 S subunits, non-programmed 80 S ribosomes and ribosomes complexed with mRNA and tRNAs was studied with the use of a derivative of the nonaribonucleotide UCUGUGUUU bearing a perfluorophenylazide group on the C-5 atom of the 5'-terminal uridine. Part of the oligonucleotide moiety of the derivative was complementary to the 5.8 S rRNA sequence ACACA in positions 82-86 flanked by two guanines at the 5'-terminus. The target for the cross-linking was identified as nucleotide G89 on the 5.8 S RNA. In addition, several ribosomal proteins were modified by the oligonucleotide derivative bound to the 5.8 S rRNA and proteins L6 and L8 were among them. Application of these results to known cryo-electron microscopy images of eukaryotic 60 S subunits made it possible to suggest that the central part of the 5.8 S rRNA containing the sequence 82-86 and proteins L6 and L8 are located at the base of the L1 stalk of the 60 S subunit. The efficacy of cross-linking in non-programmed 80 S ribosomes was much lower than in isolated 60 S subunits and in programmed 80 S ribosomes. We suggest that the difference in the accessibilities of the central part of the 5.8 S rRNA in the programmed and non-programmed 80 S ribosomes is caused by a conformational switch that seems to be required to dissociate the 80 S ribosomes into the subunits after termination of translation to allow initiation of translation of a new template.
Graifer
Dmitri
D
Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.
Molotkov
Maxim
M
Eremina
Anna
A
Ven'yaminova
Aliya
A
Repkova
Marina
M
Karpova
Galina
G
D001483:Base Sequence / Q000235:genetics; D003432:Cross-Linking Reagents / Q000378:metabolism; D015321:Gene Rearrangement / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012340:RNA, Ribosomal, 5.8S / Q000737:chemistry / Q000378:metabolism*; D012265:Ribonucleotides / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*
D003432:Cross-Linking Reagents; D012340:RNA, Ribosomal, 5.8S; D012265:Ribonucleotides; D012269:Ribosomal Proteins; C041308:ribosomal protein S40