Characterization of thylakoid division using chloroplast dividing mutants in Arabidopsis

Chloroplasts are double membrane bound organelles that are found in plants and algae. Their division requires a number of proteins to assemble into rings along the center of the organelle and to constrict in synchrony. Chloroplasts possess a third membrane system, the thylakoids, which house the majority of proteins responsible for the light-dependent reactions. The mechanism that allows chloroplasts to sort out and separate the intricate thylakoid membrane structures during organelle division remain unknown. By characterizing the sizes of thylakoids found in a number of different chloroplast division mutants in Arabidopsis, we show that thylakoids do not divide independently of the chloroplast division cycle. More specifically, we show that thylakoid division requires the formation of both the inner and the outer contractile rings of the chloroplast.

Automated summary

Chloroplasts are organelles found in plants and algae that have double membranes. They divide with the help of proteins forming rings in the center and constricting together. Chloroplasts have a third membrane system, thylakoids, which contain most of the proteins responsible for light-dependent reactions. The mechanism for separating thylakoid membrane structures during chloroplast division is still unknown. By studying different chloroplast division mutants in Arabidopsis, we found that thylakoids do not divide independently but require both inner and outer contractile rings of the chloroplast to form.