School of Engineering, University of Warwick, Coventry, UK.
Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, Italy.
Biochim Biophys Acta Bioenerg. 2018 Apr;1859(4):270-279. doi: 10.1016/j.bbabio.2018.01.008. Epub 2018 Feb 2.
The yeast Saccharomyces cerevisiae genome is endowed with two distinct isoforms of Voltage-Dependent Anion Channel (VDAC). The isoform yVDAC2 is currently understudied with respect to the best known yVDAC1. Yet, since the discovery, the function of yVDAC2 was unclear, leading to the hypothesis that it might be devoid of a channel function. In this work we have elucidated, by bioinformatics modeling and electrophysiological analysis, the functional activity of yVDAC2. The conformation of yVDAC2 and, for comparison, of yVDAC1 were modeled using a multiple template approach involving mouse, human and zebrafish structures and both showed to arrange the sequences as the typical 19-stranded VDAC β-barrel. Molecular dynamics simulations showed that yVDAC2, in comparison with yVDAC1, has a different number of permeation paths of potassium and chloride ions. yVDAC2 protein was over-expressed in the S. cerevisiae cells depleted of functional yVDAC1 (Δpor1 mutant) and, after purification, it was reconstituted in artificial membranes (planar lipid bilayer (PLB) system). The protein displayed channel-forming activity and the calculated conductance, voltage-dependence and ion selectivity values were similar to those of yVDAC1 and other members of VDAC family. This is the first time that yVDAC2 channel features are detected and characterized.
酵母酿酒酵母基因组具有两种不同的电压依赖性阴离子通道（VDAC）同工型。同工型 yVDAC2 相对于最著名的 yVDAC1 研究较少。然而，自从发现以来，yVDAC2 的功能尚不清楚，导致假设它可能缺乏通道功能。在这项工作中，我们通过生物信息学建模和电生理分析阐明了 yVDAC2 的功能活性。使用涉及小鼠、人类和斑马鱼结构的多模板方法对 yVDAC2 和 yVDAC1 的构象进行建模，两者均显示出将序列排列为典型的 19 链 VDAC β-桶。分子动力学模拟表明，yVDAC2 与 yVDAC1 相比，具有不同数量的钾离子和氯离子渗透途径。yVDAC2 蛋白在缺乏功能 yVDAC1 的酿酒酵母细胞（Δpor1 突变体）中过表达，并且在纯化后，它在人工膜（平面脂质双层（PLB）系统）中重新构成。该蛋白显示出通道形成活性，并且计算出的电导率、电压依赖性和离子选择性值与 yVDAC1 和 VDAC 家族的其他成员相似。这是首次检测和表征 yVDAC2 通道特征。
