The Phycobilisome antenna complex

The Phycobilisome (PBS) serves as the main photosynthetic light harvesting antenna complex in cyanobacteria and red-algae. The PBS is assembled by many subunits that covalently bind linear tetrapyrrole phycobilin chromophores, that strongly absorb light between 500-720nm, depending on the phycobilin type the specific protein surroundings of the phycobilin, the presence of linker proteins and the level of assembly. The PBS is attached to the

Model of the Phycobilisome (blue and cyan discs). Multiple complexes are situated in between two photosynthetic membranes close to Photosystem II (green) and Photosystem I (yellow)
Artwork by Itai Goldschmid

stromal side of the photosynthetic membranes. Absorbed sunlight energy is efficiently funneled within the PBS to terminal emitters that transfer the energy to the photochemical reaction centers of Photosystem II and Photosystem I. We have solved 13 structures of different phycobiliproteins from different species and at different levels of assembly. Each new structure reveals the electronic, atomic and molecular details of this fantastic complex. We use complimentary biophysical methods to associate the functionalities of the PBS with its structures. Ultra-fast absorption spectroscopy, time-resolved fluorescence spectroscopy, confocal microscopy, transmission electron microscopy are just some of the methods used in our research. We also use isolated PBS in different hybrid systems where we connect the complex to other protein complexes and in-organic polymers and/or electrodes to perform efficient solar energy capture.

Phycobilisomes (blue rod) is attached to Photosystem II (green), adsorbed onto special electrodes that then show production of electrical current when illuminated at a wide range of wavelengths.