The Two Conserved Cysteine Residues of the Triple Gene Block Protein 2 Are Critical for Both Cell-to-Cell and Systemic Movement of <i>Bamboo mosaic virus</i>

Tseng, Yang-Hao; Hsu, Hsiu‐Ting; Chou, Yuan‐Lin; Hu, Chung-Chi; Lin, Na-Sheng; Hsu, Yau‐Heiu; Chang, Ban‐Yang

doi:10.1094/mpmi-22-11-1379

Cited by 21 publications

(18 citation statements)

References 49 publications

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“…TGBp2 is an integral membrane protein of endoplasmic reticulum (ER) and ER-derived granular vesicles [7], [19]–[23] with both its N- and C-terminal tails exposed to the cytosol [19] and it is able to bind vRNA in a non-specific manner in vitro [24]. Ala substitutions of the two conserved Cys residues at the C-terminal tail of TGBp2 make the cell-to-cell movement of BaMV relatively inefficient and systemic movement severely inhibited [25]. TGBp3 was found to reside in the ER at the same location of replicase [26].…”

Section: Introductionmentioning

confidence: 99%

The Stable Association of Virion with the Triple-gene-block Protein 3-based Complex of Bamboo mosaic virus

et al. 2013

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The triple-gene-block protein 3 (TGBp3) of Bamboo mosaic virus (BaMV) is an integral endoplasmic reticulum (ER) membrane protein which is assumed to form a membrane complex to deliver the virus intracellularly. However, the virus entity that is delivered to plasmodesmata (PD) and its association with TGBp3-based complexes are not known. Results from chemical extraction and partial proteolysis of TGBp3 in membrane vesicles revealed that TGBp3 has a right-side-out membrane topology; i.e., TGBp3 has its C-terminal tail exposed to the outer surface of ER. Analyses of the TGBp3-specific immunoprecipitate of Sarkosyl-extracted TGBp3-based complex revealed that TGBp1, TGBp2, TGBp3, capsid protein (CP), replicase and viral RNA are potential constituents of virus movement complex. Substantial co-fractionation of TGBp2, TGBp3 and CP, but not TGBp1, in the early eluted gel filtration fractions in which virions were detected after TGBp3-specific immunoprecipitation suggested that the TGBp2- and TGBp3-based complex is able to stably associate with the virion. This notion was confirmed by immunogold-labeling transmission electron microscopy (TEM) of the purified virions. In addition, mutational and confocal microscopy analyses revealed that TGBp3 plays a key role in virus cell-to-cell movement by enhancing the TGBp2- and TGBp3-dependent PD localization of TGBp1. Taken together, our results suggested that the cell-to-cell movement of potexvirus requires stable association of the virion cargo with the TGBp2- and TGBp3-based membrane complex and recruitment of TGBp1 to the PD by this complex.

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Section: Introductionmentioning

confidence: 99%

The Stable Association of Virion with the Triple-gene-block Protein 3-based Complex of Bamboo mosaic virus

et al. 2013

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“…Alanine substitution for R16 or R21 of TGBp1 diminished the RNA-binding and NTPase activities of the protein and conse-quently restrained the virus from moving (19). Mutations of the conserved C109 or C112 of TGBp2 reduced cell-to-cell movement and severely inhibited systemic transport of the virus (29). A sorting signal in TGBp3 is necessary and sufficient for the protein to target to cortical ER tubules, a step required for BaMV cell-to-cell movement (32).…”

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confidence: 99%

The Interaction between Bamboo Mosaic Virus Replication Protein and Coat Protein Is Critical for Virus Movement in Plant Hosts

Lee

et al. 2011

J Virol

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Bamboo mosaic virus (BaMV) is a positive-sense RNA virus belonging to the genus Potexvirus. Open reading frame 1 (ORF1) encodes the viral replication protein that consists of a capping enzyme domain, a helicase-like domain (HLD), and an RNA-dependent RNA polymerase domain from the N to C terminus. ORF5 encodes the viral coat protein (CP) required for genome encapsidation and the virus movement in plants. In this study, application of a yeast-two hybrid assay detected an interaction between the viral HLD and CP. However, the interaction did not affect the NTPase activity of the HLD. To identify the critical amino acids of CP interacting with the HLD, a random mutational library of CP was created using error-prone PCR, and the mutations adversely affecting the interaction were screened by a bacterial two-hybrid system. As a result, the mutations A209G and N210S in CP were found to weaken the interaction. To determine the significance of the interaction, the mutations were introduced into a BaMV infectious clone, and the mutational effects on viral replication, movement, and genome encapsidation were investigated. There was no effect on accumulations of BaMV CP and genomic RNAs within protoplasts; however, the virus cell-to-cell movement in plants was restricted. Sequence alignment revealed that A209 of BaMV CP is conserved in many potexviruses. Mutation of the corresponding residue in Foxtail mosaic virus CP also reduced the viral HLD-CP interaction and restricted the virus movement, suggesting that interaction between CP and a widely conserved HLD in the potexviral replication protein is crucial for viral trafficking through plasmodesmata.To spread throughout hosts, plant viruses have evolved a number of pathways to allow their progeny to pass across plasmodesmata into neighboring cells and travel along the vascular system (8, 26). The virus-encoded movement proteins play a pivotal role through diverse mechanisms in these cellto-cell and vascular transports. Ancillary proteins, for example, the viral coat proteins (CPs) in some cases, and host factors may also participate in these processes. Numerous studies have been conducted to elucidate the movement mechanisms. Many of the results have been summarized in a number of recent reviews (23,28,30). They provided in-depth discussions on issues such as the identification and characterization of the involved viral and host proteins and the transport models for some exemplified viruses, such as Tobacco mosaic virus (TMV) and Potato virus X (PVX). Despite these efforts, many details of the processes remain elusive.Members of the genus Potexvirus have a positive-strand RNA genome that contains five open reading frames (ORFs), a 5Ј methyl cap, and a 3Ј poly(A) tail. ORF1 encodes the viral replication protein, consisting of a capping enzyme domain, a helicase-like domain (HLD), and an RNA-dependent RNA polymerase domain (RdRp) from the N terminus to the C terminus (16,17). The HLD has RNA 5Ј-triphosphatase and nucleoside triphosphatase (NTPase) activities (18). With the co...

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“…NbTRXh2 was revealed to target the MP TGBp2 to reduce its disulfide bond ( Figure 2 ). Also, the two conserved cysteins forming the disulfide bond were demonstrated to play a key role in BaMV movement (Tseng et al, 2009). Therefore, NbTRXh2 targets TGBp2, which could result in the loss of the structural integrity of TGBp2 and their failure to interact with other movement-associated proteins, including TGBps1 and 3.…”

Section: The Factors Involved In Defense Against Viral Rna Movementmentioning

confidence: 99%

Host Factors in the Infection Cycle of Bamboo mosaic virus

2017

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To complete the infection cycle efficiently, the virus must hijack the host systems in order to benefit for all the steps and has to face all the defense mechanisms from the host. This review involves a discussion of how these positive and negative factors regulate the viral RNA accumulation identified for the Bamboo mosaic virus (BaMV), a single-stranded RNA virus. The genome of BaMV is approximately 6.4 kb in length, encoding five functional polypeptides. To reveal the host factors involved in the infection cycle of BaMV, a few different approaches were taken to screen the candidates. One of the approaches is isolating the viral replicase-associated proteins by co-immunoprecipitation with the transiently expressed tagged viral replicase in plants. Another approach is using the cDNA-amplified fragment length polymorphism technique to screen the differentially expressed genes derived from N. benthamiana plants after infection. The candidates are examined by knocking down the expression in plants using the Tobacco rattle virus-based virus-induced gene silencing technique following BaMV inoculation. The positive or negative regulators could be described as reducing or enhancing the accumulation of BaMV in plants when the expression levels of these proteins are knocked down. The possible roles of these host factors acting on the accumulation of BaMV will be discussed.

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The Two Conserved Cysteine Residues of the Triple Gene Block Protein 2 Are Critical for Both Cell-to-Cell and Systemic Movement of Bamboo mosaic virus

Cited by 21 publications

References 49 publications

The Stable Association of Virion with the Triple-gene-block Protein 3-based Complex of Bamboo mosaic virus

The Stable Association of Virion with the Triple-gene-block Protein 3-based Complex of Bamboo mosaic virus

The Interaction between Bamboo Mosaic Virus Replication Protein and Coat Protein Is Critical for Virus Movement in Plant Hosts

Host Factors in the Infection Cycle of Bamboo mosaic virus

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