Abstract
In chloroplasts, thylakoids are built as granal stacks in a light dependent manner and form a complex membrane network. Thylakoid formation is associated with the assembly of light-harvesting antenna and photosystems. Thylakoid membranes are considered to derive from inner envelope, but molecular evidence to support this consideration is lacking. Thus, early processes involved in thylakoid membrane formation are poorly understood. Vipp1 (vesicle-inducing protein in plastids 1) has been reported to form a large complex in chloroplasts and play a role in thylakoid membrane formation, although the precise role of this protein remains unclear. To visualize Vipp1 in living cells, we generated transgenic Arabidopsis plants in which Vipp1-GFP fusion protein was over-expressed. Supporting previous observations, Vipp1-GFP fluorescence was observed as a large granule in chloroplasts. Interestingly, our live-imaging analsysis revealed that Vipp1-GFP signals move very rapidly within chloroplasts. Vipp1 granules detected occasionally looked to migrate between membranes. To examine if the observed images reflect actual Vipp1 complexes, further analysis of Vipp1-GFP is underway.
