Department of Biophysics, University of Delhi South Campus, New Delhi, 110021, India.
J Membr Biol. 2022 Feb;255(1):79-97. doi: 10.1007/s00232-022-00215-3. Epub 2022 Feb 1.
The gating of the Voltage-Dependent Anion Channel (VDAC) is linked to oxidative stress through increased generation of mitochondrial ROS with increasing mitochondrial membrane potential (ΔΨ). It has been already reported that HO increases the single-channel conductance of VDAC on a bilayer lipid membrane. On the other hand, homocysteine (Hcy) has been reported to induce mitochondria-mediated cell death. It is argued that the thiol-form of homocysteine, HTL could be the plausible molecule responsible for the alteration in the function of proteins, such as VDAC. It is hypothesized that HTL interacts with VDAC that causes functional abnormalities. An investigation was undertaken to study the interaction of HTL with VDAC under HO induced oxidative stress through biophysical and electrophysiological methods. Fluorescence spectroscopic studies indicate that HTL interacts with VDAC, but under induced oxidative stress the effect is prevented partially. Similarly, bilayer electrophysiology studies suggest that HTL shows a reduction in VDAC single-channel conductance, but the effects are partially prevented under an oxidative environment. Gly172 and His181 are predicted through bioinformatics tools to be the most plausible binding residues of HTL in Rat VDAC. The binding of HTL and HO with VDAC appears to be cooperative as per our analysis of experimental data in the light of the Hill-Langmuir equation. The binding energies are estimated to be - 4.7 kcal mol and - 2.8 kcal mol, respectively. The present in vitro studies suggest that when mitochondrial VDAC is under oxidative stress, the effects of amino acid metabolites like HTL are suppressed.
电压门控阴离子通道 (VDAC) 的门控与氧化应激有关，通过增加线粒体 ROS 的产生与线粒体膜电位 (ΔΨ) 的增加有关。已经有报道称，HO 会增加双层脂质膜上 VDAC 的单通道电导。另一方面，同型半胱氨酸 (Hcy) 已被报道会诱导线粒体介导的细胞死亡。有人认为，同型半胱氨酸的硫醇形式 HTL 可能是导致 VDAC 等蛋白质功能改变的合理分子。假设 HTL 与 VDAC 相互作用会导致功能异常。通过生物物理和电生理方法，进行了一项研究，以研究在 HO 诱导的氧化应激下 HTL 与 VDAC 的相互作用。荧光光谱研究表明 HTL 与 VDAC 相互作用，但在诱导氧化应激下，这种作用部分被阻止。类似地，双层膜电生理学研究表明 HTL 会降低 VDAC 的单通道电导，但在氧化环境下，这种影响部分被阻止。通过生物信息学工具预测 Gly172 和 His181 是 HTL 在大鼠 VDAC 中的最可能结合残基。根据我们根据 Hill-Langmuir 方程对实验数据的分析，HTL 与 HO 与 VDAC 的结合似乎是协同的。结合能分别估计为-4.7 kcal mol 和-2.8 kcal mol。本体外研究表明，当线粒体 VDAC 处于氧化应激状态时，像 HTL 这样的氨基酸代谢物的作用会被抑制。
