Rice stripe tenuivirus p2 may recruit or manipulate nucleolar functions through an interaction with fibrillarin to promote virus systemic movement

Abstract

Rice stripe virus (RSV) is the type species of the genus Tenuivirus and represents a major viral pathogen affecting rice production in East Asia. In this study, RSV p2 was fused to yellow fluorescent protein (p2-YFP) and expressed in epidermal cells of Nicotiana benthamiana. p2-YFP fluorescence was found to move to the nucleolus initially, but to leave the nucleolus for the cytoplasm forming numerous distinct bright spots there at later time points. A bimolecular fluorescence complementation (BiFC) assay showed that p2 interacted with fibrillarin and that the interaction occurred in the nucleus. Both the nucleolar localization and cytoplasmic distribution of p2-YFP fluorescence were affected in fibrillarin-silenced N. benthamiana. Fibrillarin depletion abolished the systemic movement of RSV, but not that of Tobacco mosaic virus (TMV) and Potato virus X (PVX). A Tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) method was used to diminish RSV NS2 (encoding p2) or NS3 (encoding p3) during RSV infection. Silencing of NS3 alleviated symptom severity and reduced RSV accumulation, but had no obvious effects on virus movement and the timing of symptom development. However, silencing of NS2 abolished the systemic movement of RSV. The possibility that RSV p2 may recruit or manipulate nucleolar functions to promote virus systemic infection is discussed.

The Nucleolar Fibrillarin Protein Is Required for Helper Virus-Independent Long-Distance Trafficking of a Subviral Satellite RNA in Plants

“…With the exception of Rubisco, which remained enriched in band 1, the most abundant host protein precipitating with anti-P20 IgG was a nucleolar protein, fibrillarin, which was detected in band 2 in three independent experiments (Table 1). Fibrillarin is known to interact with viral MPs and is important for long-distance trafficking of several RNA viruses (Kim et al, 2007;Taliansky et al, 2010;Semashko et al, 2012;Zheng et al, 2015). The LC-MS/MS results were confirmed by immunoblot analysis, revealing the presence of P20 and fibrillarin in the P20 co-IP complex in the HV coinfected tissues (Figures 4C and 4D).…”

“…Fibrillarin is required for rRNA processing (Barneche et al, 2000;Sáez-Vasquez et al, 2004) and is a nucleolar-localized RBP required for systemic infection of GRV (Kim et al, 2007;Canetta et al, 2008), Potato leafroll virus (Haupt et al, 2005), and Rice stripe tenuivirus (Zheng et al, 2015). Nucleolar colocalization of fibrillarin and P20 protein (Figure 7), along with detection of fibrillarin, P20 protein, and satBaMV RNA in co-IP complexes (Figures 4 and 6) but not in the fibrillarin RNAi transgenic line (Supplemental Figure 5 and Supplemental Tables 1 and 2), is consistent with the evidence for interaction of fibrillarin with satBaMV-P20 RNP complexes ( Figure 4E, Table 2).…”

Hijacking of the nucleolar protein fibrillarin by TGB1 is required for cell‐to‐cell movement of Barley stripe mosaic virus

“…). Different VPs, such as satBaMV P20 (Chang et al ., ), RSV P2 (Zheng et al ., ), hordei‐like TGB1s (Lukhovitskaya et al ., ; Semashko et al ., ), BBSV p7a (Wang et al ., ), PVA VPg (Rajamaki & Valkonen, ) and GRV ORF3 (Kim et al ., ), traffic to the nucleolus via interactions with the importin α/β or other pathway. These diverse VPs interact with Fib2 in the nucleolus and initiate the formation of viral RNP (vRNP) complex intermediates that are transported to the cytoplasm (Fig.…”

Rice grassy stunt virus nonstructural protein p5 serves as a viral suppressor of RNA silencing and interacts with nonstructural protein p3

“…It has been reported that the RSV infects not only rice plants but also maize, wheat, oat, foxtail millet, weeds and Arabidopsis [7,15,22]. Until now, several host factors have been identified that interact with RSV proteins or RNA, and those factors are thought to be recruited or manipulated by RSV and used to complete its life cycle [6,16,33]. Notably, the RSV nonstructural protein p2, a viral silencing suppressor, can bind to a rice host protein that is homologous to the suppressor of gene silencing in Arabidopsis (AtSGS3) [6].…”