Rice Stripe Tenuivirus Nonstructural Protein 3 Hijacks the 26S Proteasome of the Small Brown Planthopper via Direct Interaction with Regulatory Particle Non-ATPase Subunit 3

Abstract

The ubiquitin/26S proteasome system plays a vital role in regulating host defenses against pathogens. Previous studies have highlighted different roles for the ubiquitin/26S proteasome in defense during virus infection in both mammals and plants, but their role in the vectors that transmit those viruses is still unclear. In this study, we determined that the 26S proteasome is present in the small brown planthopper (SBPH) (Laodelphgax striatellus) and has components similar to those in plants and mammals. There was an increase in the accumulation of Rice stripe virus (RSV) in the transmitting vector SBPH after disrupting the 26S proteasome, indicating that the SBPH 26S proteasome plays a role in defense against RSV infection by regulating RSV accumulation. Yeast two-hybrid analysis determined that a subunit of the 26S proteasome, named RPN3, could interact with RSV NS3. Transient overexpression of RPN3 had no effect on the RNA silencing suppressor activity of RSV NS3. However, NS3 could inhibit the ability of SBPH rpn3 to complement an rpn3 mutation in yeast. Our findings also indicate that the direct interaction between RPN3 and NS3 was responsible for inhibiting the complementation ability of RPN3. In vivo, we found an accumulation of ubiquitinated protein in SBPH tissues where the RSV titer was high, and silencing of rpn3 resulted in malfunction of the SBPH proteasome-mediated proteolysis. Consequently, viruliferous SBPH in which RPN3 was repressed transmitted the virus more effectively as a result of higher accumulation of RSV. Our results suggest that the RSV NS3 protein is able to hijack the 26S proteasome in SBPH via a direct interaction with the RPN3 subunit to attenuate the host defense response. IMPORTANCEWe show, for the first time, that the 26S proteasome components are present in the small brown planthopper and play a role in defense against its vectored plant virus (RSV). In turn, RSV encodes a protein that subverts the SBPH 26S proteasome via direct interaction with the 26S proteasome subunit RPN3. Our results imply that the molecular arms race observed in plant hosts can be extended to the insect vector that transmits those viruses. Rice stripe virus (RSV), one of the most destructive pathogens of rice production, has been responsible for numerous epidemics since it was first described in Japan in 1897 (1-3). RSV is the type member of the Tenuivirus genus, and the viral genome consists of four single-stranded RNA segments which range in size from approximately 8.9 to 2.1 kb (4, 5). RNA 1 is negative sense and encodes a putative RNA-dependent RNA polymerase. RNAs 2, 3, and 4 are ambisense, and each contains two open reading frames (ORFs), with one on the viral RNA strand (vRNA) and the second on the viral cRNA strand (vcRNA) (6). RSV vRNA 2 encodes a membrane-associated protein that reportedly is an RNA silencing suppressor and interacts with suppressor of gene silencing 3 (SGS3) (7). vcRNA 2 encodes a glycoprotein (NSvc2) which when expressed in insect cells is displayed on the membrane su...

ADP ribosylation factor 1 facilitates spread of wheat dwarf virus in its insect vector

“…alienus , which can interact with WDV CP in both yeast two‐hybrid assay and pull‐down assay. This protein might involve in WDV spread in the tissues of leafhopper, because previous researches have showed that most viruses moved through the tissues of vector insects by directly binding to the vector's proteins (Huo, Liu, Zhang, Chen, & Li, ; Morin, Ghanim, Sobol, & Czosnek, ; Xu et al, ). For example, the specific interaction between viral nucleocapsid protein and sugar transporter 6 of Laodelphax striatellus is a key factor for determining whether the virus can invade midgut epithelial cells (Qin et al, ).…”

“…In general, once orally acquired by its insect vector, a persistent circulative virus follows a sequential pathway, from ingestion through the stylet to gut to haemolymph and finally to the salivary glands (Jia et al, ; Liu et al, ). The successful spread of virions in the insect vectors requires specific interactions between the virus and vector components to overcome membrane barriers (Linz, Liu, Chougule, & Bonning, ; Rana et al, ) or prevent degradation by the vector's immune system (Gray et al, ; Liu et al, ; Xu et al, ). The virions are thought to hijack a host mechanism that most likely enables transport of essential macromolecules (Marsh & Helenius, ; Seddas et al, ; Wang, Wu, Liu, Wu, & Wang, ).…”

The α-tubulin of Laodelphax striatellus facilitates the passage of rice stripe virus (RSV) and enhances horizontal transmission

“…Among these seven proteins, NS3 functions as a gene-silencing suppressor in plants and functions in the size-independent and noncooperative recognition of dsRNA [41,42]. A recent report demonstrated that RSV NS3 protein can hijack the 26S proteasome by interacting directly with the SBPH RPN3 protein [43]. Our observations using Y2H and GST pull-down assays confirmed that NS3 interacts with LsTUB (Fig.…”

Ubiquitin-Like protein 5 interacts with the silencing suppressor p3 of rice stripe virus and mediates its degradation through the 26S proteasome pathway

“…It has also been reported that the 26S proteasome plays a defensive role in protecting SBPH against RSV infection. The RSV p3 protein interacts with the RPN3 subunit of the 26S proteasome in SBPH and attenuates the host defense response by hijacking the 26S proteasome to facilitate viral replication [58]. We here demonstrate that the 26S proteasome functions in plants against RSV by targeting p3 for degradation, indicating that the interaction between the 26S proteasome and p3 differs between SBPH and plants (Fig 8).…”