Direct Recording of Trans-Plasma Membrane Electron Currents Mediated by a Member of the Cytochrome b561 Family of Soybean. Issue 2 (17th August 2015)

• Record Type: Journal Article
• Authors: Picco, Cristiana; Scholz-Starke, Joachim; Festa, Margherita; Costa, Alex; Sparla, Francesca; Trost, Paolo; Carpaneto, Armando
• Is Part Of: Plant physiology. Volume 169:Issue 2(2015)
• Page Start: 986
• Page End: 995
• Publication Date: 2015-08-17
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.15.00642
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : Electron currents mediated by a soybean cytochrome b561 protein are detected and functionally characterized using a classical electrophysiological approach. Abstract: Trans-plasma membrane electron transfer is achieved by b -type cytochromes of different families, and plays a fundamental role in diverse cellular processes involving two interacting redox couples that are physically separated by a phospholipid bilayer, such as iron uptake and redox signaling. Despite their importance, no direct recordings of trans-plasma membrane electron currents have been described in plants. In this work, we provide robust electrophysiological evidence of trans-plasma membrane electron flow mediated by a soybean ( Glycine max ) cytochrome b 561 associated with a dopamine β-monooxygenase redox domain (CYBDOM), which localizes to the plasma membrane in transgenic Arabidopsis ( Arabidopsis thaliana ) plants and CYBDOM complementary RNA-injected Xenopus laevis oocytes. In oocytes, two-electrode voltage clamp experiments showed that CYBDOM-mediated currents were activated by extracellular electron acceptors in a concentration- and type-specific manner. Current amplitudes were voltage dependent, strongly potentiated in oocytes preinjected with ascorbate (the canonical electron donor for cytochrome b 561), and abolished by mutating a highly conserved His residue (H292L) predicted to coordinate the cytoplasmic heme b group. We believe that this unique approach opens new perspectives in plant transmembrane electron transport and beyond.