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Conformational Ensembles from Experimental Data
and Computer Simulations
Poster Abstracts
40
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
.