Molecular and genetic characterization of the gene family encoding the voltage-dependent anion channel in Arabidopsis

Abstract

The voltage-dependent anion channel (VDAC), a major outer mitochondrial membrane protein, is thought to play an important role in energy production and apoptotic cell death in mammalian systems. However, the function of VDACs in plants is largely unknown. In order to determine the individual function of plant VDACs, molecular and genetic analysis was performed on four VDAC genes, VDAC1–VDAC4, found in Arabidopsis thaliana. VDAC1 and VDAC3 possess the eukaryotic mitochondrial porin signature (MPS) in their C-termini, while VDAC2 and VDAC4 do not. Localization analysis of VDAC–green fluorescent protein (GFP) fusions and their chimeric or mutated derivatives revealed that the MPS sequence is important for mitochondrial localization. Through the functional analysis of vdac knockout mutants due to T-DNA insertion, VDAC2 and VDAC4 which are expressed in the whole plant body are important for various physiological functions such as leaf development, the steady state of the mitochondrial membrane potential, and pollen development. Moreover, it was demonstrated that VDAC1 is not only necessary for normal growth but also important for disease resistance through regulation of hydrogen peroxide generation.

Differential targeting of VDAC3 mRNA isoforms influences mitochondria morphology

“…Moreover, they are found in various membranes-in particular, in nonmitochondrial ones (18,19). Four nucleus-encoded VDACs (VDAC1-4) have been identified in At, and the specific function of each isoform is still poorly understood (20,21). In this study, we show that APA produces two major isoforms of VDAC3 transcripts (At5g15090) that differ by the length of their 3′ UTR, one being 140 nt longer than the other.…”

“…Four VDAC genes are ubiquitously expressed in At, even if their expression patterns present clear differences (Genevestigator) (20,21). Apart from their conserved role in metabolite exchanges, the specific role of each VDAC is still unknown.…”

“…So the simplest hypothesis for VDAC3 mRNA targeting is that it allows a more efficient import of VDAC3 protein into mitochondria. The vdac3 mutants have no phenotype under normal growth conditions (20)(21)(22), so they cannot be used for complementation analyses. Because VDAC1 is the closest VDAC3 paralog (18), we transformed a vdac1 T-DNA insertion line (SALK_034653) with two VDAC3 transgenes harboring a HA tag at the N terminus of CDS and differing by their 3′ extensions (cUTR or aUTR sequences; Fig.…”

Mitochondrial Energy and Redox Signaling in Plants

“…However, the view of free and uncontrolled diffusion across the outer membrane has been challenged with transport through porins (voltage-dependent anion channel/mitochondrial porins [VDACs]) likely to be regulated. The Arabidopsis genome contains four VDAC genes, and their mutants show differential phenotypes, suggesting specific functions of the different VDAC proteins (113,216,238). Additionally, the intermembrane space (IMS) has been reported to maintain its own physiological microenvironment with respect to pH and glutathione redox potential (82,169), which requires at least limitation of diffusion.…”

Genomic survey and gene expression analysis of the VDAC gene family in rice

“…VDAC is encoded by a small gene family in the nuclear genome, it has been found in all eukaryotic species, and its properties were initially thought to be highly conserved (Colombini, 1989): Saccharomyces cerevisiae has two VDAC isoforms, mammals have three isoforms, and plants generally contain more. However, recent research has highlighted that in animals, plants, and yeasts there are significant functional differences between VDAC isoforms Tateda et al, 2011). At least three isoforms of VDAC are present in Nicotiana tabacum ) and five different VDACs are present in Arabidopsis thaliana, Lotus japonicus, and Medicago truncatula (Clausen et al, 2004;Wandrey et al, 2004;Lee et al, 2009).…”