Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia.
Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia; Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico.
J Struct Biol. 2021 Jun;213(2):107692. doi: 10.1016/j.jsb.2020.107692. Epub 2020 Dec 30.
Acrorhagin I (U-AITX-Aeq5a) is a disulfide-rich peptide identified in the aggressive organs (acrorhagi) of the sea anemone Actinia equina. Previous studies (Toxicon 2005, 46:768-74) found that the peptide is toxic in crabs, although the structural and functional properties of acrorhagin I have not been reported. In this work, an Escherichia coli (BL21 strain) expression system was established for the preparation of C,N-labelled acrorhagin I, and the solution structure was determined using NMR spectroscopy. Structurally, acrorhagin I is similar to B-IV toxin from the marine worm Cerebratulus lacteus (PDB id 1VIB), with a well-defined helical hairpin structure stabilised by four intramolecular disulfide bonds. The recombinant peptide was tested in patch-clamp electrophysiology assays against voltage-gated potassium and sodium channels, and in bacterial and fungal growth inhibitory assays and haemolytic assays. Acrorhagin I was not active against any of the ion channels tested and showed no activity in functional assays, indicating that this peptide may possess a different biological function. Metal ion interaction studies using NMR spectroscopy showed that acrorhagin I bound zinc and nickel, suggesting that its function might be modulated by metal ions or that it may be involved in regulating metal ion levels and their transport. The similarity between the structure of acrorhagin I and that of B-IV toxin from a marine worm suggests that this fold may prove to be a recurring motif in disulfide-rich peptides from marine organisms.
海葵 Acrorhagin I（U-AITX-Aeq5a）是一种在海葵 Actinia equina 的侵略性器官（acrorhagi）中发现的富含二硫键的肽。先前的研究（Toxicon 2005，46：768-74）发现该肽在螃蟹中具有毒性，尽管尚未报道 acrorhagin I 的结构和功能特性。在这项工作中，建立了用于制备 C，N 标记的 acrorhagin I 的大肠杆菌（BL21 菌株）表达系统，并使用 NMR 光谱学确定了溶液结构。结构上，acrorhagin I 与来自海洋蠕虫 Cerebratulus lacteus 的 B-IV 毒素（PDB id 1VIB）相似，具有由四个分子内二硫键稳定的明确的螺旋发夹结构。重组肽在针对电压门控钾和钠通道的膜片钳电生理学测定、在细菌和真菌生长抑制测定以及溶血测定中进行了测试。Acrorhagin I 对测试的任何离子通道均无活性，并且在功能测定中无活性，表明该肽可能具有不同的生物学功能。使用 NMR 光谱学进行的金属离子相互作用研究表明，acrorhagin I 结合锌和镍，表明其功能可能受到金属离子的调节，或者可能参与调节金属离子水平及其运输。Acrorhagin I 的结构与海洋蠕虫的 B-IV 毒素的结构相似，这表明这种折叠可能成为富含二硫键的海洋生物肽中的重复基序。
