Dynamic architecture of plant thylakoid membranes between light and dark

The architecture of photosynthetic membranes is not static, but undergoes re-organisation on illumination. Elucidation of the re-organisation helps us to understand the relation between the structure and function of the membranes.

Recent intermediate atomic resolution of the protein complexes of plant thylakoid membranes reveals an intriguing aspect of their organization into highly organized oligomeric assemblies; these super-complexes enhance structural and functional stability compared to monomers.

In contrast, little is known about the dynamic interactions of thylakoid super-complexes in vivo in the dark, in limiting light, in saturating light or in excess light where photosystem II becomes progressively photoinactivated. As well as long-term adjustments of thylakoid composition by gene expression in response to environmental cues (photosynthetic acclimation), existing super-complexes are rapidly reorganized by dynamic changes in protein structure and/or supramolecular organization within the membrane in response to light. The spectral quality of light induces limited state transitions, while light quantity induces flexible partitioning of absorbed energy between use in photosynthesis and dissipation as heat over widely fluctuating light irradiance that involves non-photochemical quenching, photosystem II photoinactivation and D1 protein repair.

Our goal is to study the structural dynamics of the supramolecular organization of the thylakoid protein complexes, particularly the dynamic structure of photosystem II in the light and in the dark, and how dynamic structural changes in grana stacking in higher plants assist function.