Host miRNA degradation by Herpesvirus saimiri small nuclear RNA requires an unstructured interacting region
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536, USA
- Corresponding author: joan.steitz{at}yale.edu
Abstract
Herpesvirus saimiri, an oncogenic herpesvirus, during latency produces seven small nuclear RNAs, called the Herpesvirus saimiri U RNAs (HSUR1–7). HSUR1 mediates degradation of the host microRNA, miR-27, via a process that requires imperfect base-pairing. The decreased levels of miR-27 lead to prolonged T-cell activation and likely contribute to oncogenesis. To gain insight into HSUR1-mediated degradation of miR-27, we probed the in vivo secondary structure of HSUR1 and coupled this with bioinformatic structural analyses. The results suggest that HSUR1 adopts a conformation different than previously believed and that the region complementary to miR-27 lacks stable structure. To determine whether HSUR1 structural flexibility is important for its ability to mediate miR-27 degradation, we performed structurally informative mutagenic analyses of HSUR1. HSUR1 mutants in which the miR-27 binding site sequence is preserved, but sequestered in predicted helices, lose their ability to decrease miR-27 levels. These results indicate that the HSUR1 miR27-binding region must be available in a conformationally flexible segment for noncoding RNA function.
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Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.054817.115.
- Received October 9, 2015.
- Accepted May 16, 2016.
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