The structure of the nucleoprotein of Influenza D shows that all Orthomyxoviridae nucleoproteins have a similar NPCORE, with or without a NPTAIL for nuclear transport

Amélie Donchet,Thibaut Crépin,Rob W.H Ruigrok,Laura Tengo,Caroline Mas,Justine Oliva,Guy Schoehn,Alice Labaronne,Mariette Ducatez,Myriam Miloudi,Francine C.A Gerard

doi:10.1038/s41598-018-37306-y

Abstract

This paper focuses on the nucleoprotein (NP) of the newly identified member of the Orthomyxoviridae family, Influenza D virus. To date several X-ray structures of NP of Influenza A (A/NP) and B (B/NP) viruses and of infectious salmon anemia (ISA/NP) virus have been solved. Here we purified, characterized and solved the X-ray structure of the tetrameric D/NP at 2.4 Å resolution. The crystal structure of its core is similar to NP of other Influenza viruses. However, unlike A/NP and B/NP which possess a flexible amino-terminal tail containing nuclear localization signals (NLS) for their nuclear import, D/NP possesses a carboxy-terminal tail (D/NPTAIL). We show that D/NPTAIL harbors a bipartite NLS and designed C-terminal truncated mutants to demonstrate the role of D/NPTAIL for nuclear transport.

Highlights

In 2011, a virus was isolated from a pig with Influenza-like symptoms in Oklahoma (USA)
Our biochemical experiments demonstrate that D/NPTAIL is involved in the interaction with importins-α and immunofluorescence showed that the wild-type D/NP goes into the nucleus whereas the mutants stay in the cytoplasm
It was shown that the oligomerization of recombinant A nucleoprotein (A/NP) and B/ NP can be modulated by the NaCl concentration[14,18,27,28]

Summary

Introduction

In 2011, a virus was isolated from a pig with Influenza-like symptoms in Oklahoma (USA). Further serological analyses showed that antibodies against this new virus failed to cross-react with IAV, IBV or ICV (1) All these results suggested it was a new genus of the Orthomyxoviridae, temporarily named C/swine/Oklahoma/1334/2011 (C/swine/OK) and Influenza D virus (IDV). The number of vRNA segments is specific to each type of Influenza viruses and related to the number of glycoproteins at the surface of the viral particle, 8 segments for IAV and IBV, 7 for IVC and IVD and 6 for Thogoto virus. These ribonucleoproteins (RNPs) are competent for both transcription and replication. Our biochemical experiments demonstrate that D/NPTAIL is involved in the interaction with importins-α and immunofluorescence showed that the wild-type D/NP goes into the nucleus whereas the mutants stay in the cytoplasm

Methods

Results

Conclusion