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Nop9 binds the central pseudoknot region of 18S rRNA
The assembly of eukaryotic ribosomes requires numerous factors that transiently associate with evolving pre-ribosomal particles. The Pumilio repeat-containing protein Nop9 briefly associates with the 90S pre-ribosome during its co-transcriptional assembly. Here, we show that Nop9 specifically binds...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Oxford University Press
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5389560/ https://www.ncbi.nlm.nih.gov/pubmed/28053123 http://dx.doi.org/10.1093/nar/gkw1323 |
Sumario: | The assembly of eukaryotic ribosomes requires numerous factors that transiently associate with evolving pre-ribosomal particles. The Pumilio repeat-containing protein Nop9 briefly associates with the 90S pre-ribosome during its co-transcriptional assembly. Here, we show that Nop9 specifically binds an 11-nucleotide sequence of 18S rRNA that forms the 3΄ side of the central pseudoknot and helix 28 in the mature subunit. Crystal structures of Nop9 in the free and RNA-bound states reveal a new type of Pumilio repeat protein with a distinct structure, target sequence and RNA-binding mode. Nop9 contains 10 Pumilio repeats arranged into a U-shaped scaffold. The target RNA is recognized by two stretches of repeats in a bipartite manner, and three central bases are unrecognized as a result of the degeneracy of repeats 6 and 7. Our data suggest that Nop9 regulates the folding of 18S rRNA at early assembly stages of 90S. |
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