Abstract
Voltage-dependent anion channels (VDACs) are essential components of the mitochondrial outer membrane. VDACs are involved in the exchange of numerous ions and molecules, from ATP to larger molecules such as tRNAs, and are supposed to adjust exchanges in response to cell signals and stresses. Four major VDACs have been identified in Arabidopsis thaliana. The goal of this study was to explore the specific functions of these proteins, in particular, in tRNA import into mitochondria and stress response. The main results were: (i) VDACs appeared to differentially interact with tRNAs, and VDAC4 could be the major tRNA channel on the outer membrane, (ii) a VDAC3 mRNA isoform was found induced by different stresses, suggesting that VDAC3 might be specifically involved in early steps of stress response and (iii) an analysis of vdac3 and vdac1 mutant lines showed that VDAC3 and VDAC1 shared some, but not all functions. In conclusion, this work brings new knowledge on VDACs, which do not appear as interchangeable pores of the outer membrane and each VDAC has its own specificity.
Highlights
The voltage-dependent anion channels (VDACs) are the major protein components of the mitochondrial outer membrane (MOM)
the outer membrane (TOM) appears to be implicated in the binding of tRNAs at the mitochondrial surface, and VDAC in the translocation step through MOM [3]
Four VDACs are found in Arabidopsis MOM and all of them are expected to exchange metabolites between cytosol and mitochondria
Summary
The voltage-dependent anion channels (VDACs) are the major protein components of the mitochondrial outer membrane (MOM). VDACs are involved in the exchange of numerous compounds between the cytosol and the inter membrane space. These compounds are ions such as Ca2+ , metabolites such as succinate or ATP, and larger molecules such as tRNA or DNA [1,2,3]. VDACs are pore-forming proteins organized in β-barrels of 19 β-strands, with an N-terminal α-helix. The channels can adopt an open state or a closed one, which controls the permeability of the pores. In addition to function in the regulation of metabolite transport, VDACs are involved in programmed cell death [1]
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