A Sec14 domain protein is required for photoautotrophic growth and chloroplast vesicle formation in <i>Arabidopsis thaliana</i>

Abstract

Significance The light reactions of photosynthesis in algae and plants occur in thylakoid membranes within the chloroplast. Previous studies have implicated membrane contact sites, vesicle trafficking, and lipid-binding proteins in the formation of thylakoids at the chloroplast inner envelope, but the molecular basis of thylakoid biogenesis and maintenance remains enigmatic. Here we show that CPSFL1 is a chloroplast Sec14 domain protein that binds lipids and can transfer phosphoinositides between membranes in vitro. In the model plant Arabidopsis , CPSFL1 is necessary for the appearance of vesicles in chloroplasts. Our results provide molecular evidence supporting an essential role of chloroplast lipid and vesicle trafficking for photoautotrophic growth.