Subcellular targeting and interactions among the Potato virus X TGB proteins

Samuels, Timmy D.; Ju, Ho-Jong; Ye, Changming; Motes, Christy M.; Blancaflor, Elison B.; Verchot, Jeanmarie

doi:10.1016/j.virol.2007.05.022

Cited by 74 publications

(90 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We were unable to detect BSMV TGB1 binding by using yeast two-hybrid analyses (Table 1), but BSMV TGB1 interactions were revealed by the use of experimental approaches differing from those used previously with potato mop-top virus (PMTV), PSLV, and PVX (9,23,34). We first obtained direct evidence for in vivo TGB1 binding by chemical cross-linking experiments.…”

Section: Discussionmentioning

confidence: 95%

Triple Gene Block Protein Interactions Involved in Movement of Barley Stripe Mosaic Virus

Lim

Bragg

Ganesan

et al. 2008

J Virol

View full text Add to dashboard Cite

Barley stripe mosaic virus (BSMV) encodes three movement proteins in an overlapping triple gene block (TGB), but little is known about the physical interactions of these proteins. We have characterized a ribonucleoprotein (RNP) complex consisting of the TGB1 protein and plus-sense BSMV RNAs from infected barley plants and have identified TGB1 complexes in planta and in vitro. Homologous TGB1 binding was disrupted by site-specific mutations in each of the first two N-terminal helicase motifs but not by mutations in two C-terminal helicase motifs. The TGB2 and TGB3 proteins were not detected in the RNP, but affinity chromatography and yeast two-hybrid experiments demonstrated that TGB1 binds to TGB3 and that TGB2 and TGB3 form heterologous interactions. These interactions required the TGB2 glycine 40 and the TGB3 isoleucine 108 residues, and BSMV mutants containing these amino acid substitution were unable to move from cell to cell. Infectivity experiments indicated that TGB1 separated on a different genomic RNA from TGB2 and TGB3 could function in limited cell-to-cell movement but that the rates of movement depended on the levels of expression of the proteins and the contexts in which they are expressed. Moreover, elevated expression of the wild-type TGB3 protein interfered with cell-to-cell movement but movement was not affected by the similar expression of a TGB3 mutant that fails to interact with TGB2. These experiments suggest that BSMV movement requires physical interactions of TGB2 and TGB3 and that substantial deviation from the TGB protein ratios expressed by the wild-type virus compromises movement.For a virus to successfully invade a plant and cause disease, it must have the ability to move from cell to cell, establish localized infection foci, enter and exit the vascular system, and develop systemic infections. To accomplish these activities, plant viruses encode one or more movement proteins (MPs) that facilitate cell-to-cell movement and vascular transport. These proteins generally localize at plasmodesmata (PD) and increase the permeability of the PD sufficiently to permit the movement of macromolecules through the desmotubule (25, 38). Many MPs have RNA binding activities, and some act in concert with other virus-encoded proteins to facilitate virus movement and other activities such as RNA unwinding (18) or suppression of gene silencing (1, 24). Several general classes of viral MPs are known to exist, and these proteins provide tools for investigating a wide range of host-virus interactions and cellular functions (25,26).The most extensively investigated MPs are members of the 30K superfamily that are encoded by a large number of RNA and DNA viruses with different genome organizations (27). Over the past 15 years, studies of the processes carried out by proteins of the 30K movement family have provided great insight into the requirements for local and long-distance transport of Tobacco mosaic virus and a number of other viruses (4,15,25,38). The triple gene block (TGB) superfamily represents anoth...

show abstract

Section: Discussionmentioning

confidence: 95%

Triple Gene Block Protein Interactions Involved in Movement of Barley Stripe Mosaic Virus

Lim

Bragg

Ganesan

et al. 2008

J Virol

View full text Add to dashboard Cite

show abstract

“…The 8 kDa PVX TGB3 is an ER-binding protein with a single, N-terminal transmembrane domain (Morozov & Solovyev, 2003;Verchot-Lubicz et al, 2007), and TGB2 and TGB3 are reported to co-localize (Ju et al, 2008;Solovyev et al, 2000). PVX TGB3 interacts with the ER network and is associated with granular vesicles induced by TGB2 (Samuels et al, 2007). The 7 kDa TGB3 of AltMV is similar in size to that of PVX (Hammond et al, 2006), but appears to behave differently.…”

Section: Introductionmentioning

confidence: 99%

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

Lim¹,

Vaira²,

Bae

et al. 2010

Journal of General Virology

View full text Add to dashboard Cite

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 sitespecific 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 chloroplastlocalization 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 longdistance movement within plants.

show abstract

“…We then tested their possible association with two other organelles, Golgi and peroxisomes. To this end, we co-expressed pREP 1-207 -GFP with either pDsRED-ST (marker for Golgi; Samuels et al, 2007) or pRTL2-MFP-RFP (marker for peroxisome), followed by microscopic observations. It was clear that these punctate bodies colocalized neither with Golgi ( Fig.…”

Section: A Subdomain In the Mtr Determines The Formation Of Punctate mentioning

confidence: 99%

Subcellular localization and membrane association of the replicase protein of grapevine rupestris stem pitting-associated virus, family Betaflexiviridae

Prosser

Xiao

et al. 2015

Journal of General Virology

View full text Add to dashboard Cite

As a member of the newly established Betaflexiviridae family, grapevine rupestris stem pittingassociated virus (GRSPaV) has an RNA genome containing five ORFs. ORF1 encodes a putative replicase polyprotein typical of the alphavirus superfamily of positive-strand ssRNA viruses. Several viruses of this superfamily have been demonstrated to replicate in structures designated viral replication complexes associated with intracellular membranes. However, structure and cellular localization of the replicase complex have not been studied for members of Betaflexiviridae, a family of mostly woody plant viruses. As a first step towards the elucidation of the replication complex of GRSPaV, we investigated the subcellular localization of full-length and truncated versions of its replicase polyprotein via fluorescent tagging, followed by fluorescence microscopy. We found that the replicase polyprotein formed distinctive punctate bodies in both Nicotiana benthamiana leaf cells and tobacco protoplasts. We further mapped a region of 76 amino acids in the methyl-transferase domain responsible for the formation of these punctate structures. The punctate structures are distributed in close proximity to the endoplasmic reticulum network. Membrane flotation and biochemical analyses demonstrate that the N-terminal region responsible for punctate structure formation associated with cellular membrane is likely through an amphipathic a helix serving as an in-plane anchor. The identity of this membrane is yet to be determined. This is, to our knowledge, the first report on the localization and membrane association of the replicase proteins of a member of the family Betaflexiviridae.

show abstract

Subcellular targeting and interactions among the Potato virus X TGB proteins

Cited by 74 publications

References 71 publications

Triple Gene Block Protein Interactions Involved in Movement of Barley Stripe Mosaic Virus

Triple Gene Block Protein Interactions Involved in Movement of Barley Stripe Mosaic Virus

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

Subcellular localization and membrane association of the replicase protein of grapevine rupestris stem pitting-associated virus, family Betaflexiviridae

Contact Info

Product

Resources

About