Enhanced Synthesis of Foreign Nuclear Protein Stimulates Viral Reproduction via the Induction of Expression.

Plants are a promising platform for recombinant protein production. Here we propose a novel approach to increase the level of viral vector-mediated recombinant protein synthesis. This approach is based on the hypothesis that antiviral protection is weakened during the antibacterial cellular response. We suggested that introduced to the cell foreign nuclear localized proteins, including effectors such as bacterial nucleomodulins, can interfere with the import of cellular nuclear proteins and launch antibacterial defense reactions, creating favorable conditions for cytoplasmic virus reproduction. Here, we performed synthesis of an artificial nuclear protein-red fluorescent protein (mRFP) fused with a nuclear localization sequence (NLS)-in plant cells as a mimetic of a bacterial effector. Superproduction of mRFP:NLS induced () mRNA accumulation. Both NLS-containing protein synthesis and increased expression stimulated reproduction of the viral vector based on the genome of crucifer-infecting tobacco mosaic virus (crTMV) in leaves. We isolated the gene promoter (Pr) and showed that Pr activity sharply increased in response to massive synthesis of GFP fused with NLS. We conclude that NLS-induced Pr activation and increased accumulation of mRNA led to the stimulation of GFP expression from crTMV: GFP vector in the transient expression system.