Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia.
Proteins. 2024 Feb;92(2):192-205. doi: 10.1002/prot.26594. Epub 2023 Oct 4.
Diverse structural scaffolds have been described in peptides from sea anemones, with the ShKT domain being a common scaffold first identified in ShK toxin from Stichodactyla helianthus. ShK is a potent blocker of voltage-gated potassium channels (K 1.x), and an analog, ShK-186 (dalazatide), has completed Phase 1 clinical trials in plaque psoriasis. The ShKT domain has been found in numerous other species, but only a tiny fraction of ShKT domains has been characterized functionally. Despite adopting the canonical ShK fold, some ShKT peptides from sea anemones inhibit K 1.x, while others do not. Mutagenesis studies have shown that a Lys-Tyr (KY) dyad plays a key role in K 1.x blockade, although a cationic residue followed by a hydrophobic residue may also suffice. Nevertheless, ShKT peptides displaying an ShK-like fold and containing a KY dyad do not necessarily block potassium channels, so additional criteria are needed to determine whether new ShKT peptides might show activity against potassium channels. In this study, we used a combination of NMR and molecular dynamics (MD) simulations to assess the potential activity of a new ShKT peptide. We determined the structure of ShKT-Ts1, from the sea anemone Telmatactis stephensoni, examined its tissue localization, and investigated its activity against a range of ion channels. As ShKT-Ts1 showed no activity against K 1.x channels, we used MD simulations to investigate whether solvent exposure of the dyad residues may be informative in rationalizing and potentially predicting the ability of ShKT peptides to block K 1.x channels. We show that either a buried dyad that does not become exposed during MD simulations, or a partially exposed dyad that becomes buried during MD simulations, correlates with weak or absent activity against K 1.x channels. Therefore, structure determination coupled with MD simulations, may be used to predict whether new sequences belonging to the ShKT family may act as potassium channel blockers.
从海葵中分离出的肽具有多种结构支架，其中 ShKT 结构域是首次在来自石珊瑚的 ShK 毒素中发现的常见支架。ShK 是一种有效的电压门控钾通道（K 1.x）阻断剂，其类似物 ShK-186（dalazatide）已完成斑块型银屑病的 1 期临床试验。ShKT 结构域已在许多其他物种中发现，但仅有一小部分 ShKT 结构域具有功能特征。尽管采用了典型的 ShK 折叠，但一些来自海葵的 ShKT 肽可抑制 K 1.x，而其他肽则不能。突变研究表明，赖氨酸-酪氨酸（KY）二联体在 K 1.x 阻断中起关键作用，尽管带正电荷的残基后面跟着疏水性残基也可能足够。然而，具有 ShK 样折叠并包含 KY 二联体的 ShKT 肽不一定能阻断钾通道，因此需要其他标准来确定新的 ShKT 肽是否可能对钾通道具有活性。在这项研究中，我们使用 NMR 和分子动力学（MD）模拟的组合来评估一种新的 ShKT 肽的潜在活性。我们确定了来自海葵 Telmatactis stephensoni 的 ShKT-Ts1 的结构，检查了其组织定位，并研究了其对一系列离子通道的活性。由于 ShKT-Ts1 对 K 1.x 通道没有活性，我们使用 MD 模拟来研究二联体残基的溶剂暴露是否可以提供信息，从而合理推断和潜在预测 ShKT 肽阻断 K 1.x 通道的能力。我们表明，要么在 MD 模拟过程中二联体不暴露，要么部分暴露但在 MD 模拟过程中被掩埋的二联体与对 K 1.x 通道的弱或无活性相关。因此，结构测定与 MD 模拟相结合，可用于预测属于 ShKT 家族的新序列是否可能作为钾通道阻断剂。
