A protein kinase binds the C-terminal domain of the readthrough protein of Turnip yellows virus and regulates virus accumulation

Abstract

Turnip yellows virus (TuYV), a phloem-limited virus, encodes a 74kDa protein known as the readthrough protein (RT) involved in virus movement. We show here that a TuYV mutant deleted of the C-terminal part of the RT protein (TuYV-∆RTCter) was affected in long-distance trafficking in a host-specific manner. By using the C-terminal domain of the RT protein as a bait in a yeast two-hybrid screen of a phloem cDNA library from Arabidopsis thaliana we identified the calcineurin B-like protein-interacting protein kinase-7 (AtCIPK7). Transient expression of a GFP:CIPK7 fusion protein in virus-inoculated Nicotiana benthamiana leaves led to local increase of wild-type TuYV accumulation, but not that of TuYV-∆RTCter. Surprisingly, elevated virus titer in inoculated leaves did not result in higher TuYV accumulation in systemic leaves, which indicates that virus long-distance movement was not affected. Since GFP:CIPK7 was localized in or near plasmodesmata, CIPK7 could negatively regulate TuYV export from infected cells.

Targeted disruption of aphid transmission: a vision for the management of crop diseases caused by Luteoviridae members

“…Identification of host plant factors that regulate interactions with the C-terminal region of the RTP involved in phloem tropism is a critical frontier of future research to manipulate virus localization in the plant. Rodriguez-Medina, Brault and colleagues showed that calcineurin-B like protein-interacting protein kinase (CIPK7) binds to the RTP C-terminal domain of TuYV [54]. Overexpression of CIPK7 in plants leads to an increase in the local accumulation of virus but did not affect systemic virus movement suggesting that CIPK7 could block virus export from infected cells by interacting with the RTP C-terminal domain [54].…”

“…Rodriguez-Medina, Brault and colleagues showed that calcineurin-B like protein-interacting protein kinase (CIPK7) binds to the RTP C-terminal domain of TuYV [54]. Overexpression of CIPK7 in plants leads to an increase in the local accumulation of virus but did not affect systemic virus movement suggesting that CIPK7 could block virus export from infected cells by interacting with the RTP C-terminal domain [54]. CIPK7 could therefore be part of a plant defense mechanism and, in this regard, regulating its expression could reduce virus accumulation and thus virus transmission by aphids.…”

Hitchhikers, highway tolls and roadworks: the interactions of plant viruses with the phloem

“…Very few host factors participating in movement of phloem-limited viruses have so far been identified. Plasmodesmata-localized calcineurin B-like-interacting protein kinase 7 (CIPK7) interacts with the RTD of Turnip yellows polerovirus and promotes an over-accumulation of the virus in inoculated cells by limiting virus exit [42]. Chaperonin Containing T-Complex Polypeptide 1, subunit 8, was identified as an interactor of the RTD of Potato leafroll polerovirus [57], and, in analogy to the role of a chaperonin in intercellular transport of the transcription factor KNOTTED 1, was suggested to assist virus transport.…”

Evaluation of a Bead-Free Coimmunoprecipitation Technique for Identification of Virus–Host Protein Interactions Using High-Resolution Mass Spectrometry

“…If the bait and prey physically interact, then proteinfragment complementation between the 2 halves of the transcription factor/fluorescent protein tags, respectively, leads to expression of a set of reporter genes or fluorescence that can be visually assessed. Although these methods have been used successfully to identify some host proteins that directly interact with individual viral proteins, 5,6 they are not amenable to studying interactions with multimeric protein complexes, such as assembled virion or virus replication factories. In addition, these techniques require extensive cloning and multiple rounds of screening, often in cells (i.e., yeast) that are outside of the biologic context of a natural infection.…”