scholarly journals Domain organization of the N-terminal portion of hordeivirus movement protein TGBp1

2009 ◽  
Vol 90 (12) ◽  
pp. 3022-3032 ◽  
Author(s):  
Valentin V. Makarov ◽  
Ekaterina N. Rybakova ◽  
Alexander V. Efimov ◽  
Eugene N. Dobrov ◽  
Marina V. Serebryakova ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Molecular Mass ◽  
Rna Binding ◽  
Triple Gene Block ◽  
Plant Viruses ◽  
Protein Domain ◽  
Helicase Domain ◽  
Long Distance ◽  
Genomic Rnas ◽  
Gene Block

Three ‘triple gene block’ proteins known as TGBp1, TGBp2 and TGBp3 are required for cell-to-cell movement of plant viruses belonging to a number of genera including Hordeivirus. Hordeiviral TGBp1 interacts with viral genomic RNAs to form ribonucleoprotein (RNP) complexes competent for translocation between cells through plasmodesmata and over long distances via the phloem. Binding of hordeivirus TGBp1 to RNA involves two protein regions, the C-terminal NTPase/helicase domain and the N-terminal extension region. This study demonstrated that the extension region of hordeivirus TGBp1 consists of two structurally and functionally distinct domains called the N-terminal domain (NTD) and the internal domain (ID). In agreement with secondary structure predictions, analysis of circular dichroism spectra of the isolated NTD and ID demonstrated that the NTD represents a natively unfolded protein domain, whereas the ID has a pronounced secondary structure. Both the NTD and ID were able to bind ssRNA non-specifically. However, whilst the NTD interacted with ssRNA non-cooperatively, the ID bound ssRNA in a cooperative manner. Additionally, both domains bound dsRNA. The NTD and ID formed low-molecular-mass oligomers, whereas the ID also gave rise to high-molecular-mass complexes. The isolated ID was able to interact with both the NTD and the C-terminal NTPase/helicase domain in solution. These data demonstrate that the hordeivirus TGBp1 has three RNA-binding domains and that interaction between these structural units can provide a basis for remodelling of viral RNP complexes at different steps of cell-to-cell and long-distance transport of virus infection.

scholarly journals RNA-binding properties of the 63 kDa protein encoded by the triple gene block of poa semilatent hordeivirus

2001 ◽  
Vol 82 (10) ◽  
pp. 2569-2578 ◽  
Author(s):  
N. O. Kalinina ◽  
D. A. Rakitina ◽  
N. E. Yelina ◽  
A. A. Zamyatnin ◽  
T. A. Stroganova ◽  
...  
Keyword(s):  
Rna Binding ◽  
Triple Gene Block ◽  
Helicase Domain ◽  
Sequence Motifs ◽  
Long Distance ◽  
Binding Properties ◽  
Gene Block ◽  
Extension Domain ◽  
Positively Charged

The 63 kDa ‘63K’ movement protein encoded by the triple gene block of poa semilatent virus (PSLV) comprises the C-terminal NTPase/helicase domain and the N-terminal extension domain, which contains two positively charged sequence motifs, A and B. In this study, the in vitro RNA-binding properties of PSLV 63K and its mutants were analysed. Membrane-immobilized 63K and N-63K (isolated N-terminal extension domain) bound RNA at high NaCl concentrations. In contrast, C-63K (isolated NTPase/helicase domain) was able to bind RNA only at NaCl concentrations of up to 50 mM. In gel-shift assays, C-63K bound RNA to form complexes that were unable to enter an agarose gel, whereas complexes formed by N-63K could enter the gel. Full-length 63K formed both types of complexes. Visualization of the RNA–protein complexes formed by 63K, N-63K and C-63K by atomic force microscopy demonstrated that each complex had a different shape. Collectively, these data indicate that 63K has two distinct RNA-binding activities associated with the NTPase/helicase domain and the N-terminal extension domain. Mutations in either of the positively charged sequence motifs A and B had little effect on the RNA binding of the N-terminal extension domain, whereas mutations in both motifs together inhibited RNA binding. Hybrid viruses with mutations in motifs A and B were able to infect inoculated leaves of Nicotiana benthamiana plants, but were unable to move systemically to uninoculated leaves, suggesting that the RNA-binding activity of the N-terminal extension domain of PSLV 63K is associated with virus long-distance movement.

scholarly journals Microscopic Analysis of Severe Structural Rearrangements of the Plant Endoplasmic Reticulum and Golgi Caused by Overexpression ofPoa semilatent virusMovement Protein

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Andrey G. Solovyev ◽  
Joachim Schiemann ◽  
Sergey Y. Morozov
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Triple Gene Block ◽  
Microscopic Analysis ◽  
Potato Virus X ◽  
Plant Viruses ◽  
Genomic Rnas ◽  
Movement Proteins ◽  
Gene Block ◽  
Ribonucleoprotein Complexes

Cell-to-cell transport of plant viruses is mediated by virus-encoded movement proteins and occurs through plasmodesmata interconnecting neighboring cells in plant tissues. Three movement proteins coded by the “triple gene block” (TGB) and named TGBp1, TGBp2 and TGBp3 have distinct functions in viral transport. TGBp1 binds viral genomic RNAs to form ribonucleoprotein complexes representing the transport form of viral genome, while TGBp2 and TGBp3 are necessary for intracellular delivery of such complexes to plasmodesmata. Recently, it was revealed that overexpression ofPotato virus XTGBp3 triggers the unfolded protein response mitigating the endoplasmic reticulum (ER) stress leading to cell death if this protein reaches high levels in the ER. Here we report microscopic studies of the influence of thePoa semilatent hordeivirusTGBp3 overexpressed inNicotiana benthamianaepidermal cells by particle bombardment on cell endomembranes and demonstrate that the protein C-terminal transmembrane segment contains a determinant responsible for vesiculation and coalescence of the endoplasmic reticulum and Golgi presumably accompanying the ER stress that can be induced upon high-level TGBp3 expression.

scholarly journals Genetic Variation and Possible Mechanisms Driving the Evolution of Worldwide Fig mosaic virus Isolates

2014 ◽  
Vol 104 (1) ◽  
pp. 108-114 ◽  
Author(s):  
Jeewan Jyot Walia ◽  
Anouk Willemsen ◽  
Eminur Elci ◽  
Kadriye Caglayan ◽  
Bryce W. Falk ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Mosaic Virus ◽  
Rna Virus ◽  
Plant Viruses ◽  
Long Distance ◽  
Evolutionary Mechanisms ◽  
Plant Materials ◽  
Genomic Rnas ◽  
Fig Trees ◽  
Fig Mosaic Virus

Fig mosaic virus (FMV) is a multipartite negative-sense RNA virus infecting fig trees worldwide. FMV is transmitted by vegetative propagation and grafting of plant materials, and by the eriophyid mite Aceria ficus. In this work, the genetic variation and evolutionary mechanisms shaping FMV populations were characterized. Nucleotide sequences from four genomic regions (each within the genomic RNAs 1, 2, 3, and 4) from FMV isolates from different countries were determined and analyzed. FMV genetic variation was low, as is seen for many other plant viruses. Phylogenetic analysis showed some geographically distant FMV isolates which clustered together, suggesting long-distance migration. The extent of migration was limited, although varied, between countries, such that FMV populations of different countries were genetically differentiated. Analysis using several recombination algorithms suggests that genomes of some FMV isolates originated by reassortment of genomic RNAs from different genetically similar isolates. Comparison between nonsynonymous and synonymous substitutions showed selection acting on some amino acids; however, most evolved neutrally. This and neutrality tests together with the limited gene flow suggest that genetic drift plays an important role in shaping FMV populations.

scholarly journals The Potato Virus X TGBp2 Protein Plays Dual Functional Roles in Viral Replication and Movement

2018 ◽  
Vol 93 (5) ◽  
Author(s):  
Xiaoyun Wu ◽  
Jiahui Liu ◽  
Mengzhu Chai ◽  
Jinhui Wang ◽  
Dalong Li ◽  
...  
Keyword(s):  
Triple Gene Block ◽  
Potato Virus X ◽  
Plant Viruses ◽  
Open Reading Frames ◽  
Movement Proteins ◽  
Gene Block ◽  
Functional Roles ◽  
Viral Rdrp ◽  
Dual Functional ◽  
Intercellular Movement

ABSTRACTPlant viruses usually encode one or more movement proteins (MP) to accomplish their intercellular movement. A group of positive-strand RNA plant viruses requires three viral proteins (TGBp1, TGBp2, and TGBp3) that are encoded by an evolutionarily conserved genetic module of three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB). However, how these three viral movement proteins function cooperatively in viral intercellular movement is still elusive. Using a novelin vivodouble-stranded RNA (dsRNA) labeling system, we showed that the dsRNAs generated by potato virus X (PVX) RNA-dependent RNA polymerase (RdRp) are colocalized with viral RdRp, which are further tightly covered by “chain mail”-like TGBp2 aggregates and localizes alongside TGBp3 aggregates. We also discovered that TGBp2 interacts with the C-terminal domain of PVX RdRp, and this interaction is required for the localization of TGBp3 and itself to the RdRp/dsRNA bodies. Moreover, we reveal that the central and C-terminal hydrophilic domains of TGBp2 are required to interact with viral RdRp. Finally, we demonstrate that knockout of the entire TGBp2 or the domain involved in interacting with viral RdRp attenuates both PVX replication and movement. Collectively, these findings suggest that TGBp2 plays dual functional roles in PVX replication and intercellular movement.IMPORTANCEMany plant viruses contain three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB), for intercellular movement. However, how the corresponding three proteins coordinate their functions remains obscure. In the present study, we provided multiple lines of evidence supporting the notion that PVX TGBp2 functions as the molecular adaptor bridging the interaction between the RdRp/dsRNA body and TGBp3 by forming “chain mail”-like structures in the RdRp/dsRNA body, which can also enhance viral replication. Taken together, our results provide new insights into the replication and movement of PVX and possibly also other TGB-containing plant viruses.

scholarly journals A minimal region in the NTPase/helicase domain of the TGBp1 plant virus movement protein is responsible for ATPase activity and cooperative RNA binding

2006 ◽  
Vol 87 (10) ◽  
pp. 3087-3095 ◽  
Author(s):  
Anna D. Leshchiner ◽  
Andrey G. Solovyev ◽  
Sergey Yu. Morozov ◽  
Natalia O. Kalinina
Keyword(s):  
Amino Acid ◽  
Atpase Activity ◽  
Amino Acid Residue ◽  
Plant Virus ◽  
Rna Binding ◽  
Triple Gene Block ◽  
Basic Amino Acid ◽  
Helicase Domain ◽  
Basic Amino Acid Residue ◽  
Conserved Sequence

The TGBp1 protein, encoded in the genomes of a number of plant virus genera as the first gene of the ‘triple gene block’, possesses an NTPase/helicase domain characterized by seven conserved sequence motifs. It has been shown that the TGBp1 NTPase/helicase domain exhibits NTPase, RNA helicase and RNA-binding activities. In this paper, we have analysed a series of deletion and point mutants in the TGBp1 proteins encoded by Potato virus X (PVX, genus Potexvirus) and Poa semilatent virus (PSLV, genus Hordeivirus) to map functional regions responsible for their biochemical activities in vitro. It was found that, in both PVX and PSLV, the N-terminal part of the TGBp1 NTPase/helicase domain comprising conserved motifs I, Ia and II was sufficient for ATP hydrolysis, RNA binding and homologous protein–protein interactions. Point mutations in a single conserved basic amino acid residue upstream of motif I had little effect on the activities of C-terminally truncated mutants of both TGBp1 proteins. However, when introduced into the full-length NTPase/helicase domains, these mutations caused a substantial decrease in the ATPase activity of the protein, suggesting that the conserved basic amino acid residue upstream of motif I was required to maintain a reaction-competent conformation of the TGBp1 ATPase active site.

scholarly journals Interactions of the TGB1 Protein during Cell-to-Cell Movement of Barley Stripe Mosaic Virus

2001 ◽  
Vol 75 (18) ◽  
pp. 8712-8723 ◽  
Author(s):  
Diane M. Lawrence ◽  
A. O. Jackson
Keyword(s):  
Subcellular Localization ◽  
Mosaic Virus ◽  
Fluorescent Protein ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Barley Stripe Mosaic Virus ◽  
Helicase Domain ◽  
Chenopodium Amaranticolor ◽  
Gene Block ◽  
Green Fluorescent

ABSTRACT We have recently used a green fluorescent protein (GFP) fusion to the γb protein of Barley stripe mosaic virus (BSMV) to monitor cell-to-cell and systemic virus movement. The γb protein is involved in expression of the triple gene block (TGB) proteins encoded by RNAβ but is not essential for cell-to-cell movement. The GFP fusion appears not to compromise replication or movement substantially, and mutagenesis experiments demonstrated that the three most abundant TGB-encoded proteins, βb (TGB1), βc (TGB3), and βd (TGB2), are each required for cell-to-cell movement (D. M. Lawrence and A. O. Jackson, Mol. Plant Pathol. 2:65–75, 2001). We have now extended these analyses by engineering a fusion of GFP to TGB1 to examine the expression and interactions of this protein during infection. BSMV derivatives containing the TGB1 fusion were able to move from cell to cell and establish local lesions in Chenopodium amaranticolor and systemic infections of Nicotiana benthamiana and barley. In these hosts, the GFP-TGB1 fusion protein exhibited a temporal pattern of expression along the advancing edge of the infection front. Microscopic examination of the subcellular localization of the GFP-TGB1 protein indicated an association with the endoplasmic reticulum and with plasmodesmata. The subcellular localization of the TGB1 protein was altered in infections in which site-specific mutations were introduced into the six conserved regions of the helicase domain and in mutants unable to express the TGB2 and/or TGB3 proteins. These results are compatible with a model suggesting that movement requires associations of the TGB1 protein with cytoplasmic membranes that are facilitated by the TGB2 and TGB3 proteins.

scholarly journals A REVIEW PAPER ON POTATO MOP-TOP VIRUS (PMTV): OCCURRENCE, PROPERTIES AND MANAGEMENT

2016 ◽  
Vol 1 (3) ◽  
pp. 129 ◽  
Author(s):  
Aqleem Abbas ◽  
Meysam Madadi
Keyword(s):  
Coat Protein ◽  
Management Strategies ◽  
Triple Gene Block ◽  
Economic Losses ◽  
Tuber Quality ◽  
Potato Tubers ◽  
Long Distance ◽  
Gene Block ◽  
Potato Mop Top Virus ◽  
Important Disease

Potato mop-top virus (PMTV) is a plant pathogenic virus that affects potatoes. The virus was initially reported from Germany but now it has spread throughout Europe, Asia, South America and North America. It is responsible for spraing symptoms (brown arcs/lines, blemishes, and rings) on potato tubers and yellow chevrons or mopping (Shortened internodes) in the leaves and stems of plants grown from infected potato tubers. PMTV causes huge economic losses due to poor tuber quality. It is an important disease in the potato growing areas of the world. PMTV is tubular rod shape and has a single stranded positive sense RNA (+ssRNA) tripartite genome. RNA 1 encodes RdRp (viral RNA-dependent RNA polymerase). Coat protein (20kDa) and a larger protein (91kDa) is encoded by RNA2. RNA2 encodes larger protein (91 kDa) by read through (RT) of the amber termination codon of the coat protein. There are three conserved moldular sets of genes known as triple gene block (TGB) which are coded by RNA3. These TGBs are involved in cell to cell or long distance movement of PMTV. In nature, PMTV is vectored and transmitted by a soil born pathogen (Plasmodiophorid (Spongospora subterranean f.sp. subterranean abbreviated as ‘Sss’) that itself causes the powdery scab disease on tubers. The disease caused by PMTV and Sss are favored by cool and damp conditions. PMTV remain in spore balls of Sss for several years even if the potato is not grown in the field. There are no efficient means to manage the virus nor its vector in an infested field, therefore, preventive measures are essential. Since PMTV along with its vector is causing important disease of potato, so understanding its molecular, biological, physical properties and management strategies is very important.

scholarly journals Characterization of the RNA-binding properties of the triple-gene-block protein 2 of Bamboo mosaic virus

2009 ◽  
Vol 6 (1) ◽  
pp. 50 ◽  
Author(s):  
Hsiu-Ting Hsu ◽  
Yang-Hao Tseng ◽  
Yuan-Lin Chou ◽  
Shiaw-Hwa Su ◽  
Yau-Heiu Hsu ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Rna Binding ◽  
Triple Gene Block ◽  
Binding Properties ◽  
Gene Block ◽  
Triple Gene Block Protein

scholarly journals Replication and trafficking of a plant virus are coupled at the entrances of plasmodesmata

2013 ◽  
Vol 201 (7) ◽  
pp. 981-995 ◽  
Author(s):  
Jens Tilsner ◽  
Olga Linnik ◽  
Marion Louveaux ◽  
Ian M. Roberts ◽  
Sean N. Chapman ◽  
...  
Keyword(s):  
Plant Virus ◽  
Plant Cell Wall ◽  
Triple Gene Block ◽  
Potato Virus X ◽  
Plant Viruses ◽  
Viral Coat Protein ◽  
Movement Proteins ◽  
Gene Block ◽  
Replication Sites ◽  
Viral Coat

Plant viruses use movement proteins (MPs) to modify intercellular pores called plasmodesmata (PD) to cross the plant cell wall. Many viruses encode a conserved set of three MPs, known as the triple gene block (TGB), typified by Potato virus X (PVX). In this paper, using live-cell imaging of viral RNA (vRNA) and virus-encoded proteins, we show that the TGB proteins have distinct functions during movement. TGB2 and TGB3 established endoplasmic reticulum–derived membranous caps at PD orifices. These caps harbored the PVX replicase and nonencapsidated vRNA and represented PD-anchored viral replication sites. TGB1 mediated insertion of the viral coat protein into PD, probably by its interaction with the 5′ end of nascent virions, and was recruited to PD by the TGB2/3 complex. We propose a new model of plant virus movement, which we term coreplicational insertion, in which MPs function to compartmentalize replication complexes at PD for localized RNA synthesis and directional trafficking of the virus between cells.

scholarly journals Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement

2010 ◽  
Vol 91 (8) ◽  
pp. 2102-2115 ◽  
Author(s):  
Hyoun-Sub Lim ◽  
Anna Maria Vaira ◽  
Hanhong Bae ◽  
Jennifer N. Bragg ◽  
Steven E. Ruzin ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Critical Role ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Potato Virus X ◽  
Start Codon ◽  
Long Distance ◽  
Mesophyll Cells ◽  
Chloroplast Targeting ◽  
Gene Block

Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants.

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