RAPID AND MASSIVE GREEN FLUORESCENT PROTEIN PRODUCTION LEADS TO FORMATION OF PROTEIN Y-BODIES IN PLANT CELLS
Although high levels of recombinant protein production can be achieved via transient expression in plant cells, the mechanism by which tolerance to the presence of recombinant protein is achieved remains unclear. Here we show that intron-optimized green fluorescent protein (GFP) encoded by a Tobacco mosaic virus vector resulted in protein pro- duction accompanied by the formation of large membrane-less GFP protein bodies called Y-bodies, which demon- strated a mainly perinuclear localization. The dimensions of the Y-bodies were heterogeneous, approaching the size of the nucleus of the cell. Experiments with extracted GFP and live cell imaging showed that Y-bodies included actively fluorescent, non-aggregated, tightly packed GFP molecules. The plant cells were likely to form Y-bodies for excluding recombinant protein from normal physiological turnover.