Connecting Chlorophyll Metabolism with Accumulation of the Photosynthetic Apparatus

Chlorophyll (Chl) is indispensable for photosynthesis. In association with Chl-binding proteins (CBPs), it is responsible for light absorption, excitation energy transfer, and charge separation within the photosynthetic complexes. By contrast, photoexcitation of free Chl and its metabolic intermediates generates hazardous reactive oxygen species (ROS). While antagonistic activities of Chl synthesis and catabolism have been mostly elucidated, the tight synchronization of these metabolic activities with the formation and dismantling of the photosynthetic complexes is poorly understood. Recently, a set of auxiliary factors were identified to adjust metabolic activities and provide accurate amounts of Chl for pigment–protein complexes. Here, we review current knowledge of post-translational coordination of Chl formation, breakdown, and turnover with the assembly and disassembly of various CBPs and highlight future research perspectives. Optimal photosynthesis and proper leaf development rely on spatiotemporal regulation of Chl metabolism.Availability of Chl is crucial for the stability, correct folding, and membrane integration of CBPs; and Chl release occurs before the proteolysis of Chl-binding proteins.A conserved Chl assembly complex identified in arabidopsis (Arabidopsis thaliana) and cyanobacteria requires auxiliary factors, which may function either as Chl carriers or scaffold proteins that facilitate the integration of Chl into CBPs at the thylakoid membranes.A suite of post-translational regulators is implicated in the regulation of various aspects of Chl metabolism, and serve to coordinate the varying demand for Chl for biogenesis, maintenance, and degradation of the pigment–protein complexes.