title: In silico model of an antenna of a phycobilisome and energy transfer rates determination by theoretical Förster approach.
abstract: Energy transfer (ET) in phycobilisomes, a macrocomplex of phycobiliproteins and linker proteins, is a process that is difficult to understand completely. A model for a rod composed of two hexamers of Phycocyanin and two hexamers of Phycoerythrin was built using an in silico approach and the three-dimensional structures of both phycobiliproteins from Gracilaria chilensis. The model was characterized and showed 125 Å wide and 230 Å high, which agree with the dimensions of a piling of four hexamers as observed in the images of subcomplexes of phycobilisomes obtained by transmission electron microscopy. ET rates between every pair of chromophores in the model were calculated using the Förster approach, and the fastest rates were selected to draw preferential ET pathways along the rod. Every path indicates that the ET is funneled toward the chromophores located at Cysteines 82 in Phycoerythrin and 84 in Phycocyanin. The chromophores that face the exterior of the rod are phycoerythrobilins, and they also show a preferential ET toward the chromophores located at the center of the rod. The values calculated, in general, agree with the experimental data reported previously, which validates the use of this experimental approach.
authors.affiliation: Laboratorio de Biofísica Molecular, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile.
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Figueroa
authors.forename: José
authors.initials: J
authors.lastname: Martínez-Oyanedel
authors.forename: Adelio R
authors.initials: AR
authors.lastname: Matamala
authors.forename: Jorge
authors.initials: J
authors.lastname: Dagnino-Leone
authors.forename: Claudia
authors.initials: C
authors.lastname: Mella
authors.forename: Rubén
authors.initials: R
authors.lastname: Fritz
authors.forename: José
authors.initials: J
authors.lastname: Sepúlveda-Ugarte
authors.forename: Marta
authors.initials: M
authors.lastname: Bunster
mesh_terms: D003198:Computer Simulation; D004735:Energy Transfer; D044724:Gracilaria / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010798:Phycocyanin / Q000737:chemistry* / Q000378:metabolism; D010799:Phycoerythrin / Q000737:chemistry* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D055503:Protein Multimerization
chemical_list: D010940:Plant Proteins; D010798:Phycocyanin; D010799:Phycoerythrin