Plastoglobules: Lipid Droplets At The Thylakoid Membrane

Plastoglobules (PG) are lipid droplets that are structurally and functionally associated with the thylakoid membranes of chloroplasts. PG thus effectively form a thylakoid membrane micro domain. The thylakoid membranes provide the environment for the photosynthetic light reactions. The thylakoid membranes in majority consist of bilayer forming galactolipids and also harbour neutral lipids, including carotenoids, chlorophylls, prenylquinones (plastoquinone, phylloquinone, tocopherols), and others. The neutral lipids participate directly in the photosynthetic light reactions, act as anti -oxidants or are metabolic products, respectively. The biosynthesis, abundance, redox state and other parameters of these compounds are tightly controlled. PG store these compounds but also actively participate in their metabolism. PG thereby contribute to continuous remodelling of the thylakoid membrane. This depends on the presence of an assortment of enzymes and regulatory kinases at PG that are involved in a wide range of processes affecting thylakoid membrane composition. Here, we review the current state of the PG field.