Viral Studies Point the Way: Mechanisms of Intercellular Transport

Peña, Eduardo José; Niehl, Annette; Heinlein, Manfred

doi:10.1007/978-1-4419-1532-0_1

Cited by 4 publications

(2 citation statements)

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“…However, once replicated, the new vRNP particles must be specifically targeted from the replication sites to PD, which likely depends on more specialized mechanisms. Consistent with this potential requirement for transport to PD, numerous studies highlighted the importance of MP associations with dynamic endoplasmic reticulum (ER) membranes and components of the cytoskeleton (Heinlein et al, 1995 , 1998 ; Boyko et al, 2000a , 2007 ; Brandner et al, 2008 ; Sambade et al, 2008 ) (for review, see Niehl and Heinlein, 2011 ; Peña et al, 2012 ). According to the current model (Figure 1 ), infection of a new cell starts with the association of the vRNP with sites on the ER.…”

Section: Vrna Transport Occurs Via the Er/actin Networkmentioning

confidence: 98%

RNA transport during TMV cell-to-cell movement

Peña¹,

Heinlein²

2012

Front. Plant Sci.

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Studies during the last 25 years have provided increasing evidence for the ability of plants to support the cell-to-cell and systemic transport of RNA molecules and that this process plays a role in plant development and in the systemic orchestration of cellular responses against pathogens and other environmental challenges. Since RNA viruses exploit the cellular RNA transport machineries for spreading their genomes between cells they represent convenient models to investigate the underlying mechanisms. In this regard, the intercellular spread of Tobacco mosaic virus (TMV) has been studied for many years. The RNA of TMV moves cell-to-cell in a non-encapsidated form in a process depending on virus-encoded movement protein (MP). Here, we discuss the current state of the art in studies using TMV and its MP as a model for RNA transport. While the ability of plants to transport viral and cellular RNA molecules is consistent with RNA transport phenomena in other systems, further studies are needed to increase our ability to visualize viral RNA (vRNA) in vivo and to distinguish RNA-transport related processes from those involved in antiviral defense.

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Section: Vrna Transport Occurs Via the Er/actin Networkmentioning

confidence: 98%

RNA transport during TMV cell-to-cell movement

Peña¹,

Heinlein²

2012

Front. Plant Sci.

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“…Whereas the tubule-guided mechanism involves the displacement of the desmotubule by the formation of a tubule-like transport structure assembled by multimerization of viral MP and the transport of whole virions through the tubule (9,(11)(12)(13)(14)(15)(16), the non-tubule-guided mechanism usually occurs in the absence of virions and does not involve structural alterations within PD but rather viral interference with the normal regulation of PD. Tobacco mosaic virus (TMV), the type virus using a non-tubule-guided mechanism, moves from cell to cell independently of the coat protein (CP) (9,17), by targeting viral replication complexes (VRCs) to PD with the help of myosin motor proteins (18). Moreover, this virus interferes with callose depositions at PD, thus allowing the passage of the VRCs into the adjacent cell (19).…”

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confidence: 99%

Citrus Psorosis Virus Movement Protein Contains an Aspartic Protease Required for Autocleavage and the Formation of Tubule-Like Structures at Plasmodesmata

Luna

Peña

Borniego

et al. 2018

J Virol

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Plant virus cell-to-cell movement is an essential step in viral infections. This process is facilitated by specific virus-encoded movement proteins (MPs), which manipulate the cell wall channels between neighboring cells known as plasmodesmata (PD). Citrus psorosis virus (CPsV) infection in sweet orange involves the formation of tubule-like structures within PD, suggesting that CPsV belongs to "tubule-forming" viruses that encode MPs able to assemble a hollow tubule extending between cells to allow virus movement. Consistent with this hypothesis, we show that the MP of CPsV (MP) indeed forms tubule-like structures at PD upon transient expression in leaves. Tubule formation by MP depends on its cleavage capacity, mediated by a specific aspartic protease motif present in its primary sequence. A single amino acid mutation in this motif abolishes MP cleavage, alters the subcellular localization of the protein, and negatively affects its activity in facilitating virus movement. The amino-terminal 34-kDa cleavage product (34K), but not the 20-kDa fragment (20K), supports virus movement. Moreover, similar to tubule-forming MPs of other viruses, MP (and also the 34K cleavage product) can homooligomerize, interact with PD-located protein 1 (PDLP1), and assemble tubule-like structures at PD by a mechanism dependent on the secretory pathway. 20K retains the protease activity and is able to cleave a cleavage-deficient MP in Altogether, these results demonstrate that CPsV movement depends on the autolytic cleavage of MP by an aspartic protease activity, which removes the 20K protease and thereby releases the 34K protein for PDLP1-dependent tubule formation at PD. Infection by citrus psorosis virus (CPsV) involves a self-cleaving aspartic protease activity within the viral movement protein (MP), which results in the production of two peptides, termed 34K and 20K, that carry the MP and viral protease activities, respectively. The underlying protease motif within the MP is also found in the MPs of other members of the family, suggesting that protease-mediated protein processing represents a conserved mechanism of protein expression in this virus family. The results also demonstrate that CPsV and potentially other ophioviruses move by a tubule-guided mechanism. Although several viruses from different genera were shown to use this mechanism for cell-to-cell movement, our results also demonstrate that this mechanism is controlled by posttranslational protein cleavage. Moreover, given that tubule formation and virus movement could be inhibited by a mutation in the protease motif, targeting the protease activity for inactivation could represent an important approach for ophiovirus control.

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