Turnip Mosaic Virus Uses the SNARE Protein VTI11 in an Unconventional Route for Replication Vesicle Trafficking

Abstract

Infection of plant cells by RNA viruses leads to the generation of organelle-like subcellular structures that contain the viral replication complex. During Turnip mosaic virus (TuMV) infection of Nicotiana benthamiana, the viral membrane protein 6K 2 plays a key role in the release of motile replication vesicles from the host endoplasmic reticulum (ER). Here, we demonstrate that 6K 2 contains a GxxxG motif within its predicted transmembrane domain that is vital for TuMV infection. Replacement of the Gly with Val within this motif inhibited virus production, and this was due to a relocation of the viral protein to the Golgi apparatus and the plasma membrane. This indicated that passage of 6K 2 through the Golgi apparatus is a dead-end avenue for virus infection. Impairing the fusion of transport vesicles between the ER and the Golgi apparatus by overexpression of the SNARE Sec22 protein resulted in enhanced intercellular virus movement. Likewise, expression of nonfunctional, Golgi-located synaptotagmin during infection enhanced TuMV intercellular movement. 6K 2 copurified with VTI11, a prevacuolar compartment SNARE protein. An Arabidopsis thaliana vti11 mutant was completely resistant to TuMV infection. We conclude that TuMV replication vesicles bypass the Golgi apparatus and take an unconventional pathway that may involve prevacuolar compartments/multivesicular bodies for virus infection.

Perception of double‐stranded RNA in plant antiviral immunity

“…Typically, plant virus replication on membranes induces strong membrane modifications and is associated with interference of virus infection with lipid metabolism and membrane targeting and transport (Altan‐Bonnet, ; De Castro et al , ; Nagy, ; Nagy and Pogany, ; Zhang et al ., , ). Infection by diverse plant viruses has been shown to imply membrane fusion processes (Garcia Cabanillas et al ., ; Huang et al ., ; Wei et al ., ) as well as conventional and unconventional protein transport routes (Diaz et al ., ; Grangeon et al ., ; Kovalev et al ., ; Movahed et al ., ; Ribeiro et al ., ; Wang et al ., ; Wei and Wang, ).…”

Remorin interacting with PCaP1 impairs Turnip mosaic virus intercellular movement but is antagonised by VPg

“…In addition to REMs which may control the ND components involved in signal recognition and transduction (Jarsch & Ott, 2011;Gui et al, 2016;Ott, 2017), callose synthase (CalS) via transmembrane domains, callose-binding proteins (PDCBs) or b-1,3-glucanases (PDBGs) via a glycophosphatidylinositol anchor target PD-PM to regulate callose deposition (Simpson et al, 2009;Benitez-Alfonso et al, 2013). Synaptotagmin A (SYTA), component of MCS, is recruited to PD upon viral infection and involved in the formation of MCS and cell-to-cell movement of viruses including TuMV (Lewis & Lazarowitz, 2010;Uchiyama et al, 2014;Amarjeet et al, 2015;Amit et al, 2015;Li et al, 2017;Cabanillas et al, 2018). As for lipids, PtdInsPs are present in PD (Grison et al, 2015) and capable of sequestering PCaP1 from actin filaments (Nagasaki et al, 2008;Qin et al, 2014).…”

Plant Cells under Attack: Unconventional Endomembrane Trafficking during Plant Defense

“…In addition to ER body accumulation and vacuolar collapse, viruses and fungi use the constitutive host endomembrane machinery for replication and establishment of feeding structures such as haustoria. The SNARE VTI11 participates in homotypic vacuole fusion events [125] and was shown to be essential for the replication of the turnip mosaic virus [126]. The resistance mechanism proposed by the authors was that the virus reroutes vesicles in a VTI11-dependent manner in order to reach the extracellular space to spread infection [127].…”