IngentaConnect Functional characterization of the evolutionarily divergent fern ...

Authors: Navarro, José A.¹; Lowe, Christian E.²; Amons, Reinout³; Kohzuma, Takamitsu⁴; Canters, Gerard W.²; De la Rosa, Miguel A.¹; Ubbink, Marcellus²; Hervás, Manuel¹

Source: FEBS Journal, Volume 271, Number 16, August 2004 , pp. 3449-3456(8)

Publisher: Blackwell Publishing

Abstract:

Plastocyanin (Pc) is a soluble copper protein that transfers electrons from cytochrome b₆f to photosystem I (PSI), two protein complexes that are localized in the thylakoid membranes in chloroplasts. The surface electrostatic potential distribution of Pc plays a key role in complex formation with the membrane-bound partners. It is practically identical for Pcs from plants and green algae, but is quite different for Pc from ferns. Here we report on a laser flash kinetic analysis of PSI reduction by Pc from various eukaryotic and prokaryotic organisms. The reaction of fern Pc with fern PSI fits a two-step kinetic model, consisting of complex formation and electron transfer, whereas other plant systems exhibit a mechanism that requires an additional intracomplex rearrangement step. The fern Pc interacts inefficiently with spinach PSI, showing no detectable complex formation. This can be explained by assuming that the unusual surface charge distribution of fern Pc impairs the interaction. Fern PSI behaves in a similar way as spinach PSI in reaction with other Pcs. The reactivity of fern Pc towards several soluble c-type cytochromes, including cytochrome f, has been analysed by flavin-photosensitized laser flash photolysis, demonstrating that the specific surface motifs for the interaction with cytochrome f are conserved in fern Pc.

Keywords: Dryopteris; fern; Nephrolepsis; photosystem I; plastocyanin

Document Type: Research article

DOI: 10.1111/j.1742-464X.2004.04283.x

Affiliations: 1: Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla y CSIC, Spain 2: Leiden Institute of Chemistry, Leiden University, the Netherlands 3: Department of Molecular Cell Biology,Leiden University Medical Center, the Netherlands 4: Faculty of Science, Ibaraki University, Mito, Japan

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Functional characterization of the evolutionarily divergent fern plastocyanin