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

Rodriguez-Medina, Caren; Boissinot, Sylvaine; Chapuis, Sophie; Gereige, Dalya; Rastegar, Maryam; Erdinger, Monique; Revers, Frederic; Ziegler-Graff, Veronique; Brault, Veronique

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

2015

Turnip yellows virus (TuYV), a phloem-limited virus, encodes a 74 kDa protein known as the readthroughprotein (RT) involved in virus movement. We show here that a TuYV mutant deleted of the C-terminalpart of the RT protein (TuYV-ΔRTCter) 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 cDNAlibrary 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 benthamianaleaves led to local increase of wild-type TuYV accumulation, but not that of TuYV-ΔRTCter. 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 ornear plasmodesmata, CIPK7 could negatively regulate TuYV export from infected cells.

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