The envelope (E) protein encoded in the genome of an RNA virus is crucial for the replication, budding and pathophysiology of the virus. In the light of the ongoing pandemic, we explored similarities/differences between SARS-CoV-1 and SARS-CoV-2 E protein ion channels in terms of their selectivity. Further, we also examined the impact of variation of the bath concentration and introduction of potential and concentration gradients across the channel on the binding ratios of sodium and chloride ions for the SARS-CoV-2 E protein. Ion transport is described through the fourth-order Poisson–Nernst–Planck–Bikerman (4PNPBik) model which generalizes the traditional model by including ionic interactions between ions and their surrounding medium and non-ionic interactions between particles due to their finite size. Governing equations are solved numerically using the immersed boundary-lattice Boltzmann method (IB-LBM). The mathematical model has been validated by comparing analytical and experimental ion activity. The SARS-CoV-1 E protein ion channel is found to be more permeable to cationic ions, while the SARS-CoV-2 E protein has similar selectivity for both cationic and anionic species. For SARS-CoV-2, an increase in the bath concentration results in an increase in the binding ratio for sodium ions. Furthermore, the chloride binding ratio increases as the concentration gradient increases. A potential gradient has a minimal effect on the binding ratio. The SARS-CoV-2 E protein was found to support higher ionic currents than the SARS-CoV-1 E protein. Furthermore, the ionic current increased with increasing bath concentrations.

中文翻译：

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通过 SARS-CoV-2 E 蛋白离子通道进行离子转运的详细研究

RNA病毒基因组中编码的包膜（E）蛋白对于病毒的复制、出芽和病理生理至关重要。鉴于正在进行的大流行，我们探讨了 SARS-CoV-1 和 SARS-CoV-2 E 蛋白离子通道在选择性方面的相似之处/不同之处。此外，我们还检查了浴液浓度的变化以及跨通道引入电位和浓度梯度对 SARS-CoV-2 E 蛋白的钠离子和氯离子结合率的影响。离子传输通过四阶 Poisson-Nernst-Planck-Bikerman (4PNPBik) 模型进行描述，该模型通过包括离子与其周围介质之间的离子相互作用以及由于其有限尺寸而导致的粒子之间的非离子相互作用来推广传统模型。使用浸入式边界格子玻尔兹曼方法 (IB-LBM) 对控制方程进行数值求解。该数学模型已通过比较分析和实验离子活度得到验证。发现 SARS-CoV-1 E 蛋白离子通道对阳离子离子更具渗透性，而 SARS-CoV-2 E 蛋白对阳离子和阴离子物种具有相似的选择性。对于 SARS-CoV-2，浴液浓度的增加会导致钠离子结合率的增加。此外，氯化物结合率随着浓度梯度的增加而增加。电位梯度对结合率的影响最小。发现 SARS-CoV-2 E 蛋白支持比 SARS-CoV-1 E 蛋白更高的离子电流。此外，离子电流随着浴浓度的增加而增加。