VDAC1 Is a Transplasma Membrane NADH-Ferricyanide Reductase

Mark A Baker,Jennifer D Ly,Darius J.R Lane,Vito De Pinto,Alfons Lawen

doi:10.1074/jbc.m311020200

Mark A Baker, Jennifer D Ly + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m311020200

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Abstract

Porin isoform 1 or VDAC (voltage-dependent anion-selective channel) 1 is the predominant protein in the outer mitochondrial membrane. We demonstrated previously that a plasma membrane NADH-ferricyanide reductase activity becomes up-regulated upon mitochondrial perturbation, and therefore suggested that it functions as a cellular redox sensor. VDAC1 is known to be expressed in the plasma membrane; however, its function there remained a mystery. Here we show that VDAC1, when expressed in the plasma membrane, functions as a NADH-ferricyanide reductase. VDAC1 preparations purified from both plasma membrane and mitochondria fractions exhibit NADH-ferricyanide reductase activity, which can be immunoprecipitated with poly- and monoclonal antibodies directed against VDAC(1). Transfecting cells with pl-VDAC1-GFP, which carries an N-terminal signal peptide, directs VDAC1 to the plasma membrane, as shown by confocal microscopy and FACS analysis, and significantly increases the plasma membrane NADH-ferricyanide reductase activity of the transfected cells. This novel enzymatic activity of the well known VDAC1 molecule may provide an explanation for its role in the plasma membrane. Our data suggest that a major function of VDAC1 in the plasma membrane is that of a NADH(-ferricyanide) reductase that may be involved in the maintenance of cellular redox homeostasis.

Highlights

Porin isoform 1 or VDAC 1 is the predominant protein in the outer mitochondrial membrane
Our data suggest that a major function of VDAC1 in the plasma membrane is that of a NADH(-ferricyanide) reductase that may be involved in the maintenance of cellular redox homeostasis
VDAC1 Is an NADH-Ferricyanide Reductase—Transplasma membrane electron transport has been established since the 1970s, mainly by the work of Fred Crane

Summary

Introduction

Porin isoform 1 or VDAC (voltage-dependent anionselective channel) 1 is the predominant protein in the outer mitochondrial membrane. Reduction of ferricyanide causes concomitant oxidation of cytosolic NADH [3], suggesting the presence of an NADHferricyanide reductase in the plasma membrane The importance of this plasma membrane redox system is exemplified by the fact that, during generation of human Namalwa ␳0 cells (which lack a functional mitochondrial respiratory chain), the rate of whole cell ferricyanide reduction increases ϳ4-fold [2]. These cells remain viable when ferricyanide is added to the media [4], suggesting a major role for the plasma membrane NADH-ferricyanide reductase in cell signaling and survival [5]. The other VDAC1 isoform, devoid of any cleavable pre-sequence, is targeted to the mitochondria, where it is efficiently inserted into the outer membrane [19]

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