Structure and function of the Toscana virus cap-snatching endonuclease

• Published in: Nucleic Acids Research
• Main Authors: Jones, Rhian, Lessoued, Sana, Meier, Kristina, Devignot, Stéphanie, Barata-García, Sergio, Mate, Maria, Bragagnolo, Gabriel, Weber, Friedemann, Rosenthal, Maria, Reguera, Juan
• Other Authors: Architecture et fonction des macromolécules biologiques (AFMB), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Bernhard Nocht Institute for Tropical Medicine - Bernhard-Nocht-Institut für Tropenmedizin Hamburg, Germany (BNITM), Justus-Liebig-Universität Gießen (JLU), Fondation pour la Recherche Medicale DCM20181039531Fondation Bettencourt Schueller AGDI-531281German Research Foundation (DFG) 197785619 SFB 1021Leibniz competition programme K72/2017Fondation pour la Recherche Medical chimiepour la medecine DCM20181039531, ANR-10-INBS-0005,FRISBI,Infrastructure Française pour la Biologie Structurale Intégrée(2010), European Project: 9732732(1998)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDV]Life Sciences [q-bio]; Arctic
• Online Access: https://hal-amu.archives-ouvertes.fr/hal-02611184; https://hal-amu.archives-ouvertes.fr/hal-02611184/document; https://hal-amu.archives-ouvertes.fr/hal-02611184/file/gkz838.pdf; https://doi.org/10.1093/nar/gkz838

International audience Toscana virus (TOSV) is an arthropod-borne human pathogen responsible for seasonal outbreaks of fever and meningoencephalitis in the Mediterranean basin. TOSV is a segmented negative-strand RNA virus (sNSV) that belongs to the genus phlebovirus (family Phenuiviridae, order Bunyavirales), encompassing other important human pathogens such as Rift Valley fever virus (RVFV). Here, we carried out a structural and functional characterization of the TOSV cap-snatching endonuclease, an N terminal domain of the viral polymerase (L protein) that provides capped 3 OH primers for transcription. We report TOSV endonuclease crystal structures in the apo form, in complex with a di-ketoacid inhibitor (DPBA) and in an intermediate state of inhibitor release , showing details on substrate binding and active site dynamics. The structure reveals substantial folding rearrangements absent in previously reported cap-snatching endonucleases. These include the relocation of the N terminus and the appearance of new structural motifs important for transcription and replication. The enzyme shows high activity rates comparable to other His+ cap-snatching en-donucleases. Moreover, the activity is dependent on conserved residues involved in metal ion and sub-strate binding. Altogether, these results bring new light on the structure and function of cap-snatching endonucleases and pave the way for the development of specific and broad-spectrum antivirals.