Print Email Facebook Twitter Viral suppressors of RNAI employ a rapid screening mode to discriminate viral RNA from cellular small RNA Title Viral suppressors of RNAI employ a rapid screening mode to discriminate viral RNA from cellular small RNA Author Fareh, M. (TU Delft BN/Chirlmin Joo Lab; Kavli institute of nanoscience Delft) van Lopik, J. (TU Delft Applied Sciences; Kavli institute of nanoscience Delft) Katechis, I. (TU Delft BN/Chirlmin Joo Lab; Kavli institute of nanoscience Delft) Bronkhorst, Alfred W. (Radboud Universiteit Nijmegen) van Eijkeren-Haagsma, A.C. (TU Delft BN/Technici en Analisten) Van Rij, Ronald P. (Radboud Universiteit Nijmegen) Joo, C. (TU Delft BN/Chirlmin Joo Lab; Kavli institute of nanoscience Delft) Faculty Applied Sciences Date 2018 Abstract RNA interference (RNAi) is an indispensable mechanism for antiviral defense in insects, including mosquitoes that transmit human diseases. To escape this antiviral defense system, viruses encode suppressors of RNAi that prevent elimination of viral RNAs, and thus ensure efficient virus accumulation. Although the first animal Viral Suppressor of RNAi (VSR) was identified more than a decade ago, the molecular basis of RNAi suppression by these viral proteins remains unclear. Here, we developed a single-molecule fluorescence assay to investigate how VSRs inhibit the recognition of viral RNAs by Dcr-2, a key endoribonuclease enzyme in the RNAi pathway. Using VSRs from three insect RNA viruses (Culex Y virus, Drosophila X virus and Drosophila C virus), we reveal bimodal physical interactions between RNA molecules and VSRs. During initial interactions, these VSRs rapidly discriminate short RNA substrates from long dsRNA. VSRs engage nearly irreversible binding with long dsRNAs, thereby shielding it from recognition by Dcr-2. We propose that the length-dependent switch from rapid screening to irreversible binding reflects the main mechanism by which VSRs distinguish viral dsRNA from cellular RNA species such as microRNAs. To reference this document use: http://resolver.tudelft.nl/uuid:7511392a-f52a-47cd-92f7-2cab6229a22e DOI https://doi.org/10.1093/nar/gkx1316 ISSN 0305-1048 Source Nucleic acids research, 46 (6), 3187-3197 Part of collection Institutional Repository Document type journal article Rights © 2018 M. Fareh, J. van Lopik, I. Katechis, Alfred W. Bronkhorst, A.C. van Eijkeren-Haagsma, Ronald P. Van Rij, C. Joo Files PDF gkx1316.pdf 1.85 MB Close viewer /islandora/object/uuid:7511392a-f52a-47cd-92f7-2cab6229a22e/datastream/OBJ/view