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Results for “movement protein”

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At least 19 recordsLinked to original sources

PubMed1998

Comparison of the coat protein, movement protein and RNA polymerase gene sequences of Australian, Chinese, and American isolates of barely yellow dwarf virus transmitted by Rhopalosiphum padi.

Barely yellow dwarf luteovirus-GPV (BYDV-GPV) is a common problem in Chinese wheat crops but is unrecorded elsewhere. A defining characteristic of GPV is its capacity to be transmitted efficiently by both Schizaphis graminum and Rhopaloshiphum padi. This dual aphid species transmission contrasts with those of BYDV-RPV and BYDV-SGV, globally distributed viruses, which are efficiently transmitted only by Rhopaloshiphum padi and Schizaphis graminum respectively. The viral RNA sequences encoding the coat protein (22K) gene, the movement protein (17K) gene, the region surrounding the conserved GDD motif of the polymerase gene and the intergenic sequences between these genes were determined for GPV and an Australian isolate of BYDV-RPV (RPVa). In all three genes, the sequences of GPV and RPVa were more similar to those of an American isolate of BYDV-RPV (RPVu) than to any other luteovirus for which there is data available. RPVa and RPVu were very similar, especially their coat proteins which had 97% identity at the amino acid level. The coat protein of GPV had 76% and 78% amino acid identity with RPVa and RPVu respectively. The data suggest that RPVu and RPVa are correctly named as strains of the same serotype and that GPV is sufficiently different from either RPV strain to be considered a distinct BYDV type. The coat protein and movement protein genes of GPV are very dissimilar to SGV. The polymerase sequences of RPVu, RPVa and GPV show close affinities with those of the sobemo-like luteoviruses and little similarity with those of the carmo-like luteoviruses. The sequences of the coat proteins, movement proteins and the polymerase segments of BYDV serotypes, other than RPV and GPV, form a cluster that is separate from their counterpart sequences from dicot-infecting luteoviruses. The RPV and GPV isolates consistently fall within a dicot-infecting cluster. This suggests that RPV and GPV evolved from within this group of viruses. Since these other viruses all infect dicots it seems likely that their common ancestor infected a dicot and that RPV and GPV evolved from a virus that switched hosts from a dicot to a monocot.

Australia↗

PubMed2004

Molecular characterization of a strain of cucumber mosaic virus based on coat protein and movement protein genes.

Cucumber mosaic virus (CMV) A strain (CMV-A) isolated from Amaranthus tricolor was partially characterized at molecular level. Complete coat protein (CP) and movement protein (MP) ORFs were cloned and sequenced. The 657 bp region of CP gene and the 840 bp region of MP gene encode 218 and 276 amino acids, respectively. CP, at nucleotide level, showed 90-98% sequence identity with the CMV subgroup I and less than 80% with the CMV subgroup II, it showed at amino acid level 92-96% identity with the subgroup I and 74-87% with the subgroup II. The nucleotide and amino acid sequence identities of MP ranged in 91-94% and 92-96%, respectively with the subgroup I but in 81-83% with the subgroup II. Phylogenetic trees generated from nucleotide and amino acid sequences of both CP and MP genes identified the virus strain as a member of the subgroup IB. CMV-A CP also displayed a remarkably higher homology with Indian strains of CMV than with other CMV strains and formed a separate cluster within the subgroup IB.

Amino Acid Sequence↗

PubMed2006

Potato virus X RNA-mediated assembly of single-tailed ternary 'coat protein-RNA-movement protein' complexes.

Different models have been proposed for the nature of the potexvirus transport form that moves from cell to cell over the infected plant: (i) genomic RNA moves as native virions; or (ii) in vitro-assembled non-virion ribonucleoprotein (RNP) complexes consisting of viral RNA, coat protein (CP) and movement protein (MP), termed TGBp1, serve as the transport form in vivo. As the structure of these RNPs has not been elucidated, the products assembled in vitro from potato virus X (PVX) RNA, CP and TGBp1 were characterized. The complexes appeared as single-tailed particles (STPs) with a helical, head-like structure composed of CP subunits located at the 5'-proximal region of PVX RNA; the TGBp1 was bound to the terminal CP molecules of the head. Remarkably, no particular non-virion RNP complexes were observed. These data suggest that the CP-RNA interactions resulting in head formation prevailed over TGBp1-RNA binding upon STP assembly from RNA, CP and TGBp1. STPs could be assembled from the 5' end of PVX RNA and CP in the absence of TGBp1. The translational ability of STPs was characterized in a cell-free translation system. STPs lacking TGBp1 were entirely non-translatable; however, they were rendered translatable by binding of TGBp1 to the end of the head. It is suggested that the RNA-mediated assembly of STPs proceeds via two steps. Firstly, non-translatable CP-RNA STPs are produced, due to encapsidation of the 5'-terminal region. Secondly, the TGBp1 molecules bind to the end of a polar head, resulting in conversion of the STPs into a translatable form.

Biological Transport, Active↗

PubMed2002

Hibiscus virus S is a new subgroup II tobamovirus: evidence from its unique coat protein and movement protein sequences.

The coat protein (CP) and movement protein (MP) sequences of a new tobamovirus infecting Hibiscus rosa-sinensis L were determined. The CP gene encodes 163 amino acid (aa) residues and with a theoretical molecular weight of 18.19 kDa. The MP gene encodes 282 amino acids and its theoretical molecular weight is 30.36 kDa. The nucleotide (nt) and aa sequences of the CP were 46.88 % to 51.63 % and 45.34 % to 57.06 % identical to other tobamoviruses, respectively. The nt and aa sequence identities of MP ranged from 38.81 % to 43.90 % and 30.85 % to 37.88 %, respectively. The predicted virion origin of assembly (OAS) was located in the CP gene. Phylogenetic trees generated based on the nt and aa sequences of both CP and MP genes indicate that this new virus clusters with members of subgroup II of tobamoviruses. Although this hibiscus virus shared a high nt and aa sequence identity with Sunn-hemp mosaic virus (SHMV), Western analysis showed that it is serologically unrelated to SHMV. We propose the name Hibiscus virus S (HVS) for this Singapore isolate. This is the first report on partial nt sequence of a tobamovirus that infects hibiscus.

Blotting, Northern↗

PubMed1994

Influence of heterologous tobamovirus movement protein and chimeric-movement protein genes on cell-to-cell and long-distance movement.

Sunn-hemp mosaic tobamovirus (SHMV) moves slowly from cell to cell in Nicotiana tabacum cv. Xanthi, but fails to move long distance. To determine the role of the SHMV movement protein (MP) in cell-to-cell and long-distance movement in tobacco, the SHMV MP gene was inserted into a TMV-cDNA clone that had approximately the 5'-half of the endogenous MP gene deleted. RNA transcripts inoculated onto tobacco induced systemic infections by 8 days postinoculation. Sequence analysis of the MP genes from purified virus isolated from systemically infected leaf tissue indicated that chimeric SHMV/TMV MP genes had been generated through RNA-RNA recombination within the 3'-termini of the MP gene sequences. When exchanged for the MP gene of TMV, three of four chimeric MP genes analyzed provided long-distance movement function for the hybrid viruses in tobacco. Two of the three hybrid viruses that moved long distance showed enhanced cell-to-cell movement relative to a recombinant TMV that expressed the intact SHMV MP gene. These observations suggest that the C-terminus of the TMV MP contains a determinant that can influence cell-to-cell movement in tobacco. A recombinant virus, TLSM, that expressed the intact SHMV MP gene exhibited cell-to-cell movement that was intermediate to SHMV and TMV, but failed to produce coat protein and was defective in long-distance movement. To further examine the role of the SHMV MP gene in long-distance movement, transgenic N. tabacum cv. Xanthi that expressed the wild-type SHMV MP gene were generated and found to facilitate rapid and efficient long-distance movement of a TMV mutant that contained a dysfunctional MP gene. Therefore, the inability of SHMV to systemically infect tobacco is a function of virus components and sequences other than those encoded by the SHMV MP gene.

Base Sequence↗

PubMed2001

Effects of movement protein mutations on the formation of tubules in plant protoplasts expressing a fusion between the green fluorescent protein and Cauliflower mosaic virus movement protein.

Fusions between the green fluorescent protein (GFP) and the Cauliflower mosaic virus (CaMV) movement protein (MP) induce the formation of fluorescent foci and surface tubules in Arabidopsis thaliana leaf mesophyll protoplasts. Tubules elongate coordinately and progressively in an assembly process approximately 6 to 12 h following transfection of protoplasts with GFP-MP constructs. Tubules are not formed in protoplasts transfected by GFP-MP(ER2A), a MP mutation that renders CaMV noninfectious. A small number of short tubules are formed on protoplasts transfected by GFP-MP(N6) and GFP-MP(N13), two second-site revertants of ER2A that partially restore infectivity. Protoplasts cotransfected with cyan fluorescent protein (CFP)-MP(WT) and GFP-MP(ER2A) form tubules containing both MP fusions, indicating that although the GFP-MP(ER2A) cannot induce tubule formation, GFP-MP(ER2A) can coassemble or colocalize with CFP-MP(WT) in tubules. Thus, CaMV MP-induced tubule formation in protoplasts correlates closely with the infectivity of mutation ER2A and its revertants, suggesting that tubule-forming capacity in plant protoplasts reflects a process required for virus infection or movement.

Arabidopsis↗

PubMed1996

A viral movement protein as a nuclear shuttle. The geminivirus BR1 movement protein contains domains essential for interaction with BL1 and nuclear localization.

For the nuclear replicating bipartite geminiviruses such as squash leaf curl to systemically infect the host requires the active participation of two virus-encoded movement proteins, BR1 and BL1. These act in a cooperative manner to transport the viral single-stranded DNA genome from its site of replication in the nucleus to the cell periphery (A.A. Sanderfoot, S.G. Lazarowitz [1995] Plant Cell 7: 1185-1194). We have proposed that BR1 functions as a nuclear shuttle protein, transporting the viral single-stranded DNA to and from the nucleus as a complex that is recognized by BL1 for movement to adjacent cells. To further investigate this, we expressed BR1 mutants known to affect viral infectivity in Spodoptera frugiperda insect cells and Nicotiana tabacum L. cv Xanthi protoplasts and found these to be defective in either their nuclear targeting or their ability to be redirected to the cell periphery when co-expressed with BL1. Translational fusions to beta-glucuronidase and alanine-scanning mutagenesis further demonstrated that the C-terminal 86 amino acids of BR1 contains a domain(s) essential for its interaction with BL1 and identified two nuclear localization signals within the N-terminal 113 residues of BR1. These nuclear localization signals were precisely located within distinct 16- and 22-peptide segments of BR1. These studies support and extend our model for squash leaf curl virus movement, showing that BR1 has a domain structure, with an N-terminal region required for nuclear targeting and a C-terminal region required for its interaction with BL1.

Amino Acid Sequence↗

PubMed2002

Cloning of a tobacco cDNA coding for a putative transcriptional coactivator MBF1 that interacts with the tomato mosaic virus movement protein.

Viral movement through plasmodesmata in host plants depends on the interaction between virus-encoded movement protein (MP) and host proteins. To search for MP-interacting protein (MIP), far-western screening of a tobacco cDNA library was carried out using a recombinant MP of tomato mosaic virus (ToMV) as a probe. One of the positive cDNA clones, designated MIP204, was highly homologous to a class of transcriptional coactivators commonly referred to as multiprotein bridging factor 1 (MBF1). ToMV MP could also bind to the Arabidopsis homologues of MBF1. The recombinant MIP204 bound to MPs of ToMV and a crucifer tobamovirus CTMV-W, but not of cucumber mosaic virus. MPs of ToMV and the related virus may interact with MBF1-like proteins to modulate host gene expression.

Arabidopsis Proteins↗

PubMed2000

P42 movement protein of Beet necrotic yellow vein virus is targeted by the movement proteins P13 and P15 to punctate bodies associated with plasmodesmata.

Cell-to-cell movement of Beet necrotic yellow vein virus (BNYVV) is driven by a set of three movement proteins--P42, P13, and P15--organized into a triple gene block (TGB) on viral RNA 2. The first TGB protein, P42, has been fused to the green fluorescent protein (GFP) and fusion proteins between P42 and GFP were expressed from a BNYVV RNA 3-based replicon during virus infection. GFP-P42, in which the GFP was fused to the P42 N terminus, could drive viral cell-to-cell movement when the copy of the P42 gene on RNA 2 was disabled but the C-terminal fusion P42-GFP could not. Confocal microscopy of epidermal cells of Chenopodium quinoa near the leading edge of the infection revealed that GFP-P42 localized to punctate bodies apposed to the cell wall whereas free GFP, expressed from the replicon, was distributed uniformly throughout the cytoplasm. The punctate bodies sometimes appeared to traverse the cell wall or to form pairs of disconnected bodies on each side. The punctate bodies co-localized with callose, indicating that they are associated with plasmodesmata-rich regions such as pit fields. Point mutations in P42 that inhibited its ability to drive cell-to-cell movement also inhibited GFP-P42 punctate body formation. GFP-P42 punctate body formation was dependent on expression of P13 and P15 during the infection, indicating that these proteins act together or sequentially to localize P42 to the plasmodesmata.

Amino Acid Sequence↗

PubMed1998

Targeting and modification of prokaryotic cell-cell junctions by tobacco mosaic virus cell-to-cell movement protein.

The movement protein (MP) of tobacco mosaic virus (TMV) facilitates the cell-to-cell spread of infection by altering the structure and function of plasmodesmata, the intercellular communication channels in plants. Because the protein was shown to interfere with intercellular communication when expressed in the cyanobacterium Anabaena sp. strain PCC 7120, whether the ability of the protein to target and to modify intercellular communication channels in plants is conserved in this prokaryote was investigated. It was found that the MP localizes to the cell junctions and induces the formation of filamentous structures that traverse the septa. It is proposed that the protein interacts with host components that are similar between plants and Anabaena and that may be evolutionarily related. The observations in Anabaena suggest that the MP modifies plasmodesmata by forming a filamentous aggregate within the pore.

Cell Communication↗

PubMed2001

A dysfunctional movement protein of tobacco mosaic virus interferes with targeting of wild-type movement protein to microtubules.

The Tobacco mosaic virus (TMV) movement protein (MPTMV) mediates cell-to-cell viral trafficking by altering properties of the plasmodesmata (Pd) in infected cells. During the infection cycle, MPTMV becomes transiently associated with endomembranes, microfilaments, and microtubules (MT). It has been shown that the cell-to-cell spread of TMV is reduced in plants expressing the dysfunctional MP mutant MPNT-1. To expand our understanding of the MP function, we analyzed events occurring during the intracellular and intercellular targeting of MPTMV and MPNT-1 when expressed as a fusion protein to green fluorescent protein (GFP), either by biolistic bombardment in a viral-free system or from a recombinant virus. The accumulation of MPTMV:GFP, when expressed in a viral-free system, is similar to MPTMV:GFP in TMV-infected tissues. Pd localization and cell-to-cell spread are late events, occurring only after accumulation of MP:GFP in aggregate bodies and on MT in the target cell. MPNT-1:GFP localizes to MT but does not target to Pd nor does it move cell to cell. The spread of transiently expressed MPTMV:GFP in leaves of transgenic plants that produce MPNT-1 is reduced, and targeting of the MPTMV:GFP to the cytoskeleton is inhibited. Although MPTMV:GFP targets to the Pd in these plants, it is partially impaired for movement. It has been suggested that MPNT-1 interferes with host-dependent processes that occur during the intracellular targeting program that makes MP movement competent.

Cucumis sativus↗

PubMed2006

Disruption of microtubule organization and centrosome function by expression of tobacco mosaic virus movement protein.

The movement protein (MP) of Tobacco mosaic virus mediates the cell-to-cell transport of viral RNA through plasmodesmata, cytoplasmic cell wall channels for direct cell-to-cell communication between adjacent cells. Previous in vivo studies demonstrated that the RNA transport function of the protein correlates with its association with microtubules, although the exact role of microtubules in the movement process remains unknown. Since the binding of MP to microtubules is conserved in transfected mammalian cells, we took advantage of available mammalian cell biology reagents and tools to further address the interaction in flat-growing and transparent COS-7 cells. We demonstrate that neither actin, nor endoplasmic reticulum (ER), nor dynein motor complexes are involved in the apparent alignment of MP with microtubules. Together with results of in vitro coprecipitation experiments, these findings indicate that MP binds microtubules directly. Unlike microtubules associated with neuronal MAP2c, MP-associated microtubules are resistant to disruption by microtubule-disrupting agents or cold, suggesting that MP is a specialized microtubule binding protein that forms unusually stable complexes with microtubules. MP-associated microtubules accumulate ER membranes, which is consistent with a proposed role for MP in the recruitment of membranes in infected plant cells and may suggest that microtubules are involved in this process. The ability of MP to interfere with centrosomal gamma-tubulin is independent of microtubule association with MP, does not involve the removal of other tested centrosomal markers, and correlates with inhibition of centrosomal microtubule nucleation activity. These observations suggest that the function of MP in viral movement may involve interaction with the microtubule-nucleating machinery.

Animals↗

PubMed2001

Brome mosaic virus replicase proteins localize with the movement protein at infection-specific cytoplasmic inclusions in infected barley leaf cells.

Subcellular localization of the Brome mosaic virus replicase-related 1a and 2a proteins, and the 3a movement protein in infected barley leaves was examined by immunogold electron microscopy. The 1a and 2a proteins colocalized at infection-specific electron-dense cytoplasmic inclusions. The 3a protein was also detected in these inclusions. The inclusions were oval or amorphous, and contained electron-lucent regions. Electron microscopic autoradiography showed that the inclusions were sites of [3H]uridine incorporation, suggesting that they are sites of viral RNA synthesis.

Bromovirus↗

PubMed2001

An Arabidopsis thaliana protein interacts with a movement protein of Turnip crinkle virus in yeast cells and in vitro.

Plant virus movement proteins bind host components to promote virus movement from initially infected cells to neighbouring cells. In this study, cDNA clones encoding p8 and p9, two small proteins required for the movement of Turnip crinkle virus, were used as 'bait' in a yeast two-hybrid system to screen an Arabidopsis thaliana cDNA library for interactive proteins. One A. thaliana clone was identified that encodes a protein, designated Atp8, which interacted with p8 in yeast cells and in vitro. The apparent full-length of Atp8 mRNA was sequenced and shown to encode a protein with two possible transmembrane helices, several potential phosphorylation sites and two 'RGD' sequences.

Amino Acid Sequence↗

PubMed1997

Effects of coat protein mutations and reduced movement protein expression on infection spread by cowpea chlorotic mottle virus and its hybrid derivatives.

Previously we have reported that the essential 3a movement gene of icosahedral cowpea chlorotic mottle virus (CCMV) can be functionally replaced by the 30-kDa movement gene of rod-shaped sunn-hemp mosaic virus (SHMV). Because plant RNA viruses differ in requiring or not requiring coat protein for systemic infection, we have now investigated whether systemic spread by this CCMV/SHMV hybrid is dependent on its CCMV coat protein as well as its SHMV movement protein. We find that either deletion or frameshift mutations in the coat protein gene block systemic spread. Thus, like wild-type CCMV, systemic infection by the hybrid is dependent on both movement protein and coat protein. These results further support the conclusion that the required functions of the coat and movement proteins in CCMV spread do not depend on sequence-specific interaction between these proteins. Additional features of the hybrid also motivated testing the effects of modulating movement protein expression. Creating an extra, out-of-frame translational start codon (AUG) shortly upstream of the 3a movement protein gene in CCMV downregulated its expression 18-fold. Nevertheless, for CCMV derivatives bearing either the CCMV 3a gene or the SHMV 30-kDa gene, the extra AUG resulted in only a minor delay in the onset of viral spread and little or no effect on the subsequent rate of cell-to-cell spread. Thus, under normal circumstances, the rate of CCMV cell-to-cell spread in cowpea plants appears to be limited primarily by factors other than movement protein synthesis.

Amino Acid Sequence↗

PubMed2005

Evidence for interaction between the 2a polymerase protein and the 3a movement protein of Cucumber mosaic virus.

The genome of Cucumber mosaic virus consists of three single-stranded RNA molecules, RNAs 1, 2 and 3. RNAs 1 and 2 encode the 1a and 2a proteins, respectively, which are necessary for replication of the viral genome and have been implicated in movement of the viral RNAs in plants. The 3a movement protein (MP), encoded by RNA 3, is essential for transferring the RNA genomes from infected cells to adjacent cells across the plasmodesmata. Far-Western analysis demonstrated that bacterially expressed 2a polymerase protein directly interacted with the MP. Interaction was confirmed in a yeast two-hybrid assay, and co-immunoprecipitation analysis showed that the MP interacted only with the 2a polymerase protein. A yeast three-hybrid assay showed that the 1a-2a protein interaction relevant for replicase complex formation was not affected by the MP. Although the MP has no affinity for the 1a protein, it interacted indirectly with the 1a protein via the 2a polymerase protein. These results suggest that the replicase complex may be involved in movement through its interaction with the MP.

Cucumovirus↗

PubMed2000

Formation of surface tubules and fluorescent foci in Arabidopsis thaliana protoplasts expressing a fusion between the green fluorescent protein and the cauliflower mosaic virus movement protein.

The movement protein (MP) of cauliflower mosaic virus (CaMV) is a multifunctional protein that potentiates the cell-to-cell and long distance movement of the virus. Functional domains in the CaMV MP were determined by analyzing deletions in green fluorescent protein (GFP)-MP fusions transfected into Arabidopsis thaliana leaf protoplasts. GFP-MP accumulated at fluorescent foci at the cell periphery and in tubular structures extending from the protoplast surface. A region located near the center of MP was required for targeting GFP-MP to foci, whereas a larger region extending nearly to the N-terminus was needed for tubule formation. Cytoskeletal assembly inhibitors did not disrupt tubule formation or the accumulation of GFP-MP at foci, but brefeldin A, which disrupts the plant cell endomembrane system, did interfere with the formation of tubules but not foci.

Antiviral Agents↗

PubMed1996

Expression and biochemical analyses of the recombinant potato virus X 25K movement protein.

The 25K movement protein (MP) of potato virus X (PVX) is encoded by the 5'-proximal gene of three overlapping MP genes forming a 'triple gene block'. The PVX 25K MP (putative NTPase-helicase) has been synthesized in Escherichia coli as a recombinant containing a six-histidine tag at the amino terminus. The His-tagged 25K protein was purified in a one-column Ni-chelate affinity chromatography procedure. In the absence of any other viral factors, this protein had obvious Mg2+-dependent ATPase activity, which was stimulated slightly (1.7-1.9-fold) by various polynucleotides. Like other viral proteins possessing ATPase-helicase motifs and many plant viral movement proteins, the PVX 25K MP was able to bind nucleic acids in vitro. The RNA binding activity of the 25K MP was pronounced only at very low salt concentrations and was independent of its ATPase activity.

Acid Anhydride Hydrolases↗