The lattice-like structure observed by Vipp1-GFP in arabidopsis chloroplasts

Abstract

Vipp1 (vesicle inducing protein in plastids 1) is proposed to play a role in thylakoid biogenesis. It is closely related to PspA (phage shock protein A), a bacterial protein that is induced under stress conditions. Despite its discovery a decade ago and extensive analysis in cyanobacteria, green algae and higher plants, the precise role of Vipp1 in the process of chloroplast development remains unclear. In this research, we expressed Vipp1 C-terminally fused to GFP (Vipp1-GFP) in Arabidopsis and found that Vipp1 is able to assemble into rod-shaped supercomplexes. Vipp1-GFP can rescue heterotrophic growth of a vipp1 knock-down mutant, suggesting that it complements Vipp1 function. Interestingly, Vipp1-GFP rods always appeared to cross with each other to form a lattice-like structure, which is similar to a scaffold structure formed by PspA in Escherichia coli. Based on these results, we infer that Vipp1 is involved in not only thylakoid biogenesis but chloroplast envelope integrity.