Making a living off the rainbow’s edge: How phycobilisomes adapt structurally to absorb far-red light

Abstract

Cyanobacteria harvest light by using architecturally complex, soluble, light-harvesting complexes known as phycobilisomes. Phycobilisome diversity includes specialized paralogs that can be specific regions of the light spectrum; some cyanobacterial lineages can even absorb far-red light. In a recent issue of JBC, Gisriel et al. reported the cryo-electron microscopic structure of a far-red phycobilisome core, showing how bilin-binding in the α-subunits of phycocyanin paralogs can modify the bilin binding site to shift the absorbance spectrum. This work helps explain how cyanobacteria can grow in environments where most of the visible light has been filtered out.