The structure at 2 A resolution of Phycocyanin from Gracilaria chilensis and the energy transfer network in a PC-PC complex.
Phycocyanin is a phycobiliprotein involved in light harvesting and conduction of light to the reaction centers in cyanobacteria and red algae. The structure of C-phycocyanin from Gracilaria chilensis was solved by X-ray crystallography at 2.0 A resolution in space group P2(1). An interaction model between two PC heterohexamers was built, followed by molecular dynamic refinement. The best model showed an inter-hexamer rotation of 23 degrees . The coordinates of a PC heterohexamer (alphabeta)(6) and of the PC-PC complex were used to perform energy transfer calculations between chromophores pairs using the fluorescence resonance energy transfer approach (FRET). Two main intra PC ((I)beta(3)(82)-->(I)alpha(1)(84)-->(I)alpha(5)(84)-->(I)beta(6)(82) and (I)beta(3)(153)-->(I)beta(5)(153)) and two main inter PC ((I)beta(6)(82)-->(II)beta(3)(82) and (I)beta(5)(153)-->(II)beta(3)(153)) pathways were proposed based on the values of the energy transfer constants calculated for all the chromophore pairs in the hexamer and in the complex.
Contreras-Martel
Carlos
C
Institut de Biologie Structurale, CEA-CNRS-UJF, Grenoble, France.
Matamala
Adelio
A
Bruna
Carola
C
Poo-Caamaño
German
G
Almonacid
Daniel
D
Figueroa
Maximiliano
M
Martínez-Oyanedel
José
J
Bunster
Marta
M
D018360:Crystallography, X-Ray; D004735:Energy Transfer; D044724:Gracilaria / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D015394:Molecular Structure; D010798:Phycocyanin / Q000737:chemistry*
D046911:Macromolecular Substances; D010798:Phycocyanin