Structure, biogenesis and evolution of thylakoid membranes.

Cyanobacteria and chloroplasts of algae and plants harbor specialized thylakoid membranes that convert sunlight into chemical energy. These membranes house photosystems II and I, the vital protein-pigment complexes that drive oxygenic photosynthesis. In the course of their evolution, thylakoid membranes have diversified in structure. However, the core machinery for photosynthetic electron transport remained largely unchanged, with adaptations occurring primarily in the light-harvesting antenna systems. Whereas thylakoid membranes in cyanobacteria are relatively simple they become more complex in algae and plants. The chloroplasts of vascular plants contain intricate networks of stacked grana and unstacked stroma thylakoids. This review provides an in-depth view of thylakoid membrane architectures in phototrophs, and the determinants that shape their forms, as well as presenting recent insights into the spatial organization of their biogenesis and maintenance. Its overall goal is to define the underlying principles that have guided the evolution of these bioenergetic membranes.