Association of host protein VARICOSE with HCPro within a multiprotein complex is crucial for RNA silencing suppression, translation, encapsidation and systemic spread of potato virus A infection

Show full item record



Permalink

http://hdl.handle.net/10138/321524

Citation

Swarnalok , D , Pollari , M , Varjosalo , M & Mäkinen , K 2020 , ' Association of host protein VARICOSE with HCPro within a multiprotein complex is crucial for RNA silencing suppression, translation, encapsidation and systemic spread of potato virus A infection ' , PLoS Pathogens , vol. 16 , no. 10 , 1008956 . https://doi.org/10.1371/journal.ppat.1008956

Title: Association of host protein VARICOSE with HCPro within a multiprotein complex is crucial for RNA silencing suppression, translation, encapsidation and systemic spread of potato virus A infection
Author: Swarnalok, De; Pollari, Maija; Varjosalo, Markku; Mäkinen, Kristiina
Other contributor: University of Helsinki, Department of Microbiology
University of Helsinki, Department of Microbiology
University of Helsinki, Biosciences
University of Helsinki, Department of Microbiology





Date: 2020-10
Language: eng
Number of pages: 32
Belongs to series: PLoS Pathogens
ISSN: 1553-7366
DOI: https://doi.org/10.1371/journal.ppat.1008956
URI: http://hdl.handle.net/10138/321524
Abstract: In this study, we investigated the significance of a conserved five-amino acid motif 'AELPR' in the C-terminal region of helper component-proteinase (HCPro) for potato virus A (PVA; genusPotyvirus) infection. This motif is a putative interaction site for WD40 domain-containing proteins, including VARICOSE (VCS). We abolished the interaction site in HCPro by replacing glutamic acid (E) and arginine (R) with alanines (A) to generate HCPro(WD). These mutations partially eliminated HCPro-VCS co-localization in cells. We have earlier described potyvirus-induced RNA granules (PGs) in which HCPro and VCS co-localize and proposed that they have a role in RNA silencing suppression. We now demonstrate that the ability of HCPro(WD)to induce PGs, introduce VCS into PGs, and suppress RNA silencing was impaired. Accordingly, PVA carrying HCPro(WD)(PVA(WD)) infectedNicotiana benthamianaless efficiently than wild-type PVA (PVA(WT)) and HCPro(WD)complemented the lack of HCPro in PVA gene expression only partially. HCPro was purified from PVA-infected leaves as part of high molecular weight (HMW) ribonucleoprotein (RNP) complexes. These complexes were more stable when associated with wild-type HCPro than with HCPro(WD). Moreover, VCS and two viral components of the HMW-complexes, viral protein genome-linked and cylindrical inclusion protein were specifically decreased in HCPro(WD)-containing HMW-complexes. A boost in translation of replication-deficient PVA (PVA(Delta GDD)) was observed only if viral RNA expressed wild-type HCPro. The role of VCS-VPg-HCPro coordination in PVA translation was further supported by results from VCS silencing and overexpression experiments and by significantly elevated PVA-derivedRenillaluciferase vs PVA RNA ratio upon VPg-VCS co-expression. Finally, we found that PVA(WD)was unable to form virus particles or to spread systemically in the infected plant. We highlight the role of HCPro-VCS containing multi-protein assemblies associated with PVA RNA in protecting it from degradation, ensuring efficient translation, formation of stable virions and establishment of systemic infection. Author summary This study revealed that the potyviral helper component proteinase (HCPro) and the host protein VARICOSE (VCS) are linked in a manner that is important for suppression of RNA silencing, formation of potyvirus-induced RNA granules, translation of viral proteins, stability of virions, and development of systemic potato virus A (PVA) infection. The results suggest that HCPro and VCS belong to the core components of large RNP complexes regulating PVA infection. We suggest that these complexes protect viral RNAs in the cytoplasm after release from the replication complex and direct them to translation and intact to the viral particles.
Subject: 1182 Biochemistry, cell and molecular biology
HELPER COMPONENT PROTEINASE
LONG-DISTANCE MOVEMENT
MOSAIC-VIRUS
COAT PROTEIN
MOLECULAR INSIGHTS
DECAPPING COMPLEX
POTYVIRUS
REPLICATION
DOMAIN
REPRESSION
Rights:


Files in this item

Total number of downloads: Loading...

Files Size Format View
journal.ppat.1008956.pdf 6.196Mb PDF View/Open

This item appears in the following Collection(s)

Show full item record