The viral nucleocapsid protein and the human RNA-binding protein Mex3A promote translation of the Andes orthohantavirussmall mRNA.

Jorge Vera-Otarola,Jenniffer Angulo,Francisco M Barriga,Marcelo Lopez-Lastra,Estefania Castillo-Vargas,Eduard Batlle,Peter Sarnow

doi:10.1371/journal.ppat.1009931

Abstract

The capped Small segment mRNA (SmRNA) of the Andes orthohantavirus (ANDV) lacks a poly(A) tail. In this study, we characterize the mechanism driving ANDV-SmRNA translation. Results show that the ANDV-nucleocapsid protein (ANDV-N) promotes in vitro translation from capped mRNAs without replacing eukaryotic initiation factor (eIF) 4G. Using an RNA affinity chromatography approach followed by mass spectrometry, we identify the human RNA chaperone Mex3A (hMex3A) as a SmRNA-3’UTR binding protein. Results show that hMex3A enhances SmRNA translation in a 3’UTR dependent manner, either alone or when co-expressed with the ANDV-N. The ANDV-N and hMex3A proteins do not interact in cells, but both proteins interact with eIF4G. The hMex3A–eIF4G interaction showed to be independent of ANDV-infection or ANDV-N expression. Together, our observations suggest that translation of the ANDV SmRNA is enhanced by a 5’-3’ end interaction, mediated by both viral and cellular proteins.

Highlights

The Andes orthohantavirus (ANDV), a rodent-borne member of the Hantaviridae family of the Bunyavirales order, is the etiological agent of hantavirus cardiopulmonary syndrome (HCPS) in Argentina and Chile [1]
ANDV is unique among other members of the Hantaviridae family of viruses because of its ability to spread from person to person
We sought to establish if the N of ANDV (ANDV-N) could stimulate in vitro messenger RNAs (mRNAs) translation

Summary

Introduction

The Andes orthohantavirus (ANDV), a rodent-borne member of the Hantaviridae family of the Bunyavirales order, is the etiological agent of hantavirus cardiopulmonary syndrome (HCPS) in Argentina and Chile [1]. Transcription of the genomic RNA segments yields the 5’-7-methylguanosine (m7GTP) capped L, M, and S messenger RNAs (mRNAs). The mRNAs of orthohantavirus acquire their 5’cap- through a cap-snatching mechanism occurring in cytoplasmic processing bodies (P bodies) [5]. Unlike most cellular mRNAs, the ANDV SmRNA and the LmRNA lack 3’poly(A) tails [6]. The LmRNA encodes a viral RNA-dependent RNA polymerase required for viral RNA transcription and replication [7,8]. The MmRNA encodes the glycoprotein precursor, which is cotranslationally processed, generating Gc and Gn, the two viral envelope glycoproteins [9]. The SmRNA encodes for the nucleocapsid protein (N) and the nonstructural S segment (NSs) protein [10,11]. The N-protein of other orthohantavirus participates in viral mRNA translation [12]

Methods

Results

Discussion

Conclusion