MPB2C, a Microtubule-Associated Plant Factor, Is Required for Microtubular Accumulation of Tobacco Mosaic Virus Movement Protein in Plants

Abstract

Movement protein binding 2C (MPB2C) is a plant endogenous microtubule-associated protein previously identified as an interaction partner of tobacco (Nicotiana tabacum) mosaic virus movement protein (TMV-MP). In this work, the role of MPB2C in cell-to-cell transport of TMV-MP, viral spread of TMV, and subcellular localization of TMV-MP was examined. To this end, plants with reduced MPB2C levels were generated by a gene-silencing strategy. Local and systemic spread of TMV and cell-tocell movement of TMV-MP were unimpaired in MPB2C-silenced plants as compared to nonsilenced plants, indicating that MPB2C is not required for intercellular transport of TMV-MP itself or spread of TMV. However, a clear change in subcellular distribution of TMV-MP characterized by a nearly complete loss of microtubular localization was observed in MPB2C-silenced plants. This result shows that the MPB2C is a central player in determining the complex subcellular localization of TMV-MP, in particular its microtubular accumulation, a phenomenon that has been frequently observed and whose role is still under discussion. Clearly, MPB2C mediated accumulation of TMV-MP at microtubules is not required for intercellular spread but may be a means to withdraw the TMV-MP from the cell-to-cell transport pathway.

Identification of Tobacco Proteins Associated with the Stem-Loop 1 RNAs of Potato virus X

“…For instance, MBF1-like protein binds to Tomato mosaic virus (ToMV) MP and this interaction could modulate host gene expression to suppress the general defense response in plants (Matsushita et al, 2002). MPB2C and NtMPIP1 are involved in TMV cell-to-cell spread by interacting with TMV MP (Curin et al, 2007;Kragler et al, 2003). NtCPIP2a and NtCPIP2b act as potyviral susceptibility factors during Potato virus Y infection and along with heat shock protein 70, they act as plant chaperones and are essential for virus movement (Hofius et al, 2007).…”

The TobamovirusTurnip Vein Clearing Virus30-Kilodalton Movement Protein Localizes to Novel Nuclear Filaments To Enhance Virus Infection

“…This last finding and other studies (9)(10)(11)(12) have led to the suggestion that microtubules direct MP TMV to be degraded via proteasomes. However, the role of microtubules in TMV infection remains controversial (1,12).…”

The Tobacco mosaic virus Movement Protein Associates with but Does Not Integrate into Biological Membranes

“…However, this topological working model cannot explain several TMV MP properties. Some RNA-binding domains (2) or interactions with microtubules (9,17), chaperones (18), or cell wallassociated proteins (19) rely on TMV MP regions that are not accessible in the current model. Further investigations of the interaction of MPs with cellular membranes are needed to obtain a more complete understanding of the role of MPs in virus infection and cell-to-cell spread.…”