Structure and function of the Toscana virus cap-snatching endonuclease Rhian Jones, Sana Lessoued, Kristina Meier, Stéphanie Devignot, Sergio Barata-García, Maria Mate, Gabriel Bragagnolo, Friedemann Weber, Maria Rosenthal, Juan Reguera
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Rhian Jones, Sana Lessoued, Kristina Meier, Stéphanie Devignot, Sergio Barata-García, et al.. Struc- ture and function of the Toscana virus cap-snatching endonuclease. Nucleic Acids Research, Oxford University Press, 2019, 47, pp.10914-10930. 10.1093/nar/gkz838. hal-02611184
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Distributed under a Creative Commons Attribution - NonCommercial| 4.0 International License 10914–10930 Nucleic Acids Research, 2019, Vol. 47, No. 20 Published online 4 October 2019 doi: 10.1093/nar/gkz838 Structure and function of the Toscana virus cap-snatching endonuclease Rhian Jones1,†, Sana Lessoued1,†, Kristina Meier3,Stephanie´ Devignot4, Sergio Barata-Garc´ıa1, Maria Mate1, Gabriel Bragagnolo1, Friedemann Weber 4, Maria Rosenthal 3 and Juan Reguera 1,2,*
1Aix-Marseille Universite,´ CNRS, AFMB UMR 7257, 13288 Marseille, France, 2INSERM, AFMB UMR7257,13288 Marseille, France, 3Bernhard Nocht Institute for Tropical Medicine, Department of Virology, D-20359 Hamburg, Downloaded from https://academic.oup.com/nar/article-abstract/47/20/10914/5580917 by guest on 18 May 2020 Germany and 4Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, D-35392 Giessen, Germany
Received March 11, 2019; Revised September 14, 2019; Editorial Decision September 17, 2019; Accepted October 01, 2019
ABSTRACT INTRODUCTION Toscana virus (TOSV) is an arthropod-borne hu- Toscana virus (TOSV) is a member of the genus phle- man pathogen responsible for seasonal outbreaks of bovirus (family Phenuiviridae,orderBunyavirales), that in- fever and meningoencephalitis in the Mediterranean cludes several arthropod-borne human pathogens such as basin. TOSV is a segmented negative-strand RNA Sandfly fever sicilian virus (SFSV), Severe fever with throm- virus (sNSV) that belongs to the genus phlebovirus bocytopenia syndrome virus (SFTSV) or Rift Valley fever virus (RVFV), that cause outbreaks in the Mediterranean (family Phenuiviridae, order Bunyavirales), encom- basin, Asia, and sub-Saharan Africa, respectively. Symp- passing other important human pathogens such as toms range from mild to severe central nervous system in- Rift Valley fever virus (RVFV). Here, we carried out fections (TOSV, SFSV) up to hemorrhagic fevers (SFTSV, a structural and functional characterization of the RV F V ) ( 1–3). The absence of efficient drugs and vaccines TOSV cap-snatching endonuclease, an N terminal for these emerging pathogens means that there is an urgent domain of the viral polymerase (L protein) that pro- need for research and development of tools for their diag- vides capped 3 OH primers for transcription. We re- nostics and treatment. port TOSV endonuclease crystal structures in the Like all segmented negative-strand RNA viruses apo form, in complex with a di-ketoacid inhibitor (sNSVs), Phenuiviridae family members use a ‘cap- (DPBA) and in an intermediate state of inhibitor re- snatching’ mechanism to initiate transcription of the viral lease, showing details on substrate binding and ac- genome. By this mechanism, host cell messenger RNAs (mRNAs) are sequestered and cleaved by the EN around 11 tive site dynamics. The structure reveals substan- nucleotides downstream of the capped 5 end. The resulting tial folding rearrangements absent in previously re- small capped RNA fragments are then used for the initia- ported cap-snatching endonucleases. These include tion of viral transcription by the L protein RNA-dependent the relocation of the N terminus and the appear- RNA polymerase (RdRp) domain. Cap-snatching has been ance of new structural motifs important for transcrip- extensively structurally and biochemically characterized tion and replication. The enzyme shows high activ- for influenza virus, which replicates in the cell nucleus and ity rates comparable to other His+ cap-snatching en- has a heterotrimeric polymerase instead of the monomeric donucleases. Moreover, the activity is dependent on L protein present in bunyaviruses (4). The comparison of conserved residues involved in metal ion and sub- the structures of influenza A and B polymerases illustrated strate binding. Altogether, these results bring new the possible mechanics underlying this process; whereby light on the structure and function of cap-snatching the cap binding domain (in the PB2 subunit), captures the cellular mRNA and orientates it towards the EN domain endonucleases and pave the way for the develop- (at the N terminus of the PA subunit) for its cleavage ment of specific and broad-spectrum antivirals. before re-directing the RNA into the RdRp catalytic site (in the PB1 subunit) for priming transcription initiation (5–7). Bunyavirales carry out cap-snatching by their mul- tifunctional L protein, which harbours the EN at the N
*To whom correspondence should be addressed. Tel: +33 491 825 582; Fax: +33 491 266 720; Email: [email protected] †The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.