Just like in yeast and animal cells, vacuoles in plants are responsible for breaking down unwanted cellular components. At the same time, vacuoles in seeds also serve the opposite role -storing large amounts of proteins that provide energy during germination. These storage proteins, accumulated in the vacuoles of seeds such as beans and wheat, are not only vital for plant growth but also represent an important agricultural resource closely tied to our daily diet.
Until now, it was entirely unknown whether proteins could be transported from the vacuole to other organelles. In a study now published in Nature Plants, Dr. Yihong Feng (Specially Appointed Assistant Professor) and Professor Takashi Ueda at the National Institute for Basic Biology in Japan, together with their collaborators, demonstrated in the model plant Arabidopsis thaliana the existence of a retrograde trafficking pathway that retrieves the membrane protein VAMP727 from the vacuolar membrane back to endosomes. The team further identified the molecular machinery responsible for this pathway.
Dr. Feng commented, "The sorting nexin proteins that function in this newly discovered pathway have independently diversified in plants compared to animals and yeast. Our findings indicate that this trafficking route is a plant-specific innovation."
Professor Ueda added, "We were able to show that the plant-unique membrane fusion protein VAMP727 co-evolved with a recycling mechanism from the vacuole. This suggests that the evolution of vacuolar protein transport in seed plants, which is essential for massive storage protein accumulation, was closely tied to the emergence of this retrograde pathway."
This study reveals part of the unique membrane trafficking network that plants have evolved during their history, providing new insights into both cell biology and plant science.
