Conformational Ensembles from Experimental Data and Computer Simulations

Conformational Ensembles from Experimental Data and Computer Simulations

Poster Abstracts

7-POS Board 7 Structural Studies of a Phycobilisome Marta Bunster , Maximiliano Figueroa, José Martínez-Oyanedel, Jorge Dagnino-Leone, Aleikar José Vásquez. n/a, Concepción, Chile. The structure of a Phycobilisome is strictly related to its function of light harvesting and energy transfer towards the photoreaction center. Phycobilisome is a macro complex of phycobiliproteins and linker proteins that in Gracilaria chilensis , an eukaryotic red algae, is associated to thylakoyds. Each phycobilisome is formed by a CORE of Allophycocyanin from which radiate RODS formed by Phycocyanin and Phycoerythrin. A common feature of all phycobiliproteins is that they are formed by alfa/beta heterodimers that oligomerize to trimers or hexamers originating ring structures that are piled up as in an antenna. Each phycobiliprotein contains chromophores bound to specific cysteine residues. We have been studying this complex by using experimental approaches such as molecular biology and biochemistry techniques, biophysical approaches such as X-ray crystallography, and spectroscopy, as well as molecular simulations in silico . Electron microscopy provide evidences for a three cyllinders core of Allophycocyanin, 5 to 6 rods of Phycoerythrin and Phycocyanin in the PBS. The three dimensional structures of all the phycobiliproteins were determined by X ray diffraction, and their association to form rods and the core was approached by in silico and in vitro studies. Variation of subunits and the presence of linkers were also approached by transcriptomics, biochemical techniques and spectroscopy. All this information is presented in a model for the structure and function of the phycobilisome of Gracilaria chilensis .

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