Transient binding of plastocyanin to its physiological partners modifies the copper site geometry

PMID: 17064694 PMID Help

Authors: Irene Diaz-moreno (Instituto de Bioquimica Vegetal y Fotosintesis de Sevilla) , Antonio Diaz-quintana (Instituto de Bioquimica Vegetal y Fotosintesis de Sevilla) , Sofia Diaz-moreno (Diamond Light Source) , Gloria Subias (Instituto de Ciencia de Materiales de Aragon) , Miguel A. De La Rosa (Instituto de Bioquimica Vegetal y Fotosintesis de Sevilla)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Febs Letters , VOL 580 , PAGES 6187-6194

State: Published (Approved)
Published: November 2006

Abstract: The transient complexes of plastocyanin with cytochrome f and photosystem I are herein used as excellent model systems to investigate how the metal sites adapt to the changes in the protein matrix in transient complexes that are involved in redox reactions. Thus, both complexes from the cyanobacterium Nostoc sp. PCC 7119 (former Anabaena sp. PCC 7119) have been analysed by X-ray absorption spectroscopy. Our data are consistent with a significant distortion of the trigonal pyramidal geometry of the Cu coordination sphere when plastocyanin binds to cytochrome f, no matter their redox states are. The resulting tetrahedral geometry shows a shortening of the distance between Cu and the S(delta) atom of its ligand Met-97, with respect to the crystallographic structure of free plastocyanin. On the other hand, when plastocyanin binds to photosystem I instead of cytochrome f, the geometric changes are not significant but a displacement in charge distribution around the metal centre can be observed. Noteworthy, the electronic density around the Cu atom increases or decreases when oxidised plastocyanin binds to cytochrome f or photosystem I, respectively, thus indicating that the protein matrix affects the electron transfer between the two partners during their transient interaction.

Journal Keywords: X-Ray Absorption Spectroscopy; Electron-Transfer Reactions; Nostoc Sp Pcc-7119; Cytochrome-F; Photosystem-I; Anabaena-Variabilis; Cyanobacterial Plastocyanin; Hydrophobic Interactions; Reduction Potentials; Reduced Plastocyanin

Subject Areas: Biology and Bio-materials, Chemistry

Facility: ESRF

Added On: 19/04/2010 18:16

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