Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, 76230, Mexico.
Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico.
Insect Biochem Mol Biol. 2020 Sep;124:103416. doi: 10.1016/j.ibmb.2020.103416. Epub 2020 Jun 24.
Almost all marine snails within superfamily Conoidea produce venoms containing numerous neuroactive peptides. Most toxins characterized from members of this superfamily are produced by species belonging to family Conidae. These toxins (conotoxins) affect diverse membrane proteins, such as voltage- and ligand-gated ion channels, including nicotinic acetylcholine receptors (nAChRs). Family Turridae has been considerably less studied than their Conidae counterpart and, therefore, turrid toxins (turritoxins) have just been barely described. Consequently, in this work the most prominent chromatographic (RP-HPLC) fractions from the East Pacific species Polystira nobilis venom duct extract were isolated. The biological activity of six selected fractions was assayed on human (h) α7 AChRs expressed in Xenopus laevis oocytes. One of these fractions, F21, inhibited the acetylcholine-elicited response by 62 ± 12%. Therefore, this fraction was further purified and the F21-2 peptide was obtained. This peptide (at 5.6 μM) strongly and irreversibly inhibited the acetylcholine-induced response on hα7 and hα3β2 nAChRs, by 55 ± 4 and 91 ± 1%, respectively. Electrospray mass spectrometry indicates that the average molecular mass of this toxin is 12 358.80 Da. The affinity for hα3β2 nAChRs is high (IC of 566.2 nM). A partial sequence without cysteines was obtained by automated Edman degradation: WFRSFKSYYGHHGSVYRPNEPNFRSFAS…; blastp search revealed that this sequence has low similarity to some non-Cys-containing turripeptides. This is the first report of a turritoxin from a species of the American Pacific and the second description of a turripeptide inhibiting nAChRs.
几乎所有超科 Conoidea 的海洋蜗牛都产生含有多种神经活性肽的毒液。从这个超科的成员中得到的大多数毒素都是由属于 Conidae 科的物种产生的。这些毒素（conotoxins）影响多种膜蛋白，如电压门控和配体门控离子通道，包括烟碱型乙酰胆碱受体（nAChRs）。与它们的 Conidae 对应物相比，Turridae 家族受到的研究要少得多，因此，turrid 毒素（turritoxins）只是刚刚被描述过。因此，在这项工作中，从东太平洋物种 Polystira nobilis 毒腺提取物中分离出最显著的色谱（RP-HPLC）级分。六种选定级分的生物活性在表达于非洲爪蟾卵母细胞的人（h）α7 AChRs 上进行了测定。其中一个级分 F21 抑制乙酰胆碱引发的反应达 62±12%。因此，该级分进一步纯化，得到 F21-2 肽。该肽（在 5.6 μM 时）强烈且不可逆地抑制 hα7 和 hα3β2 nAChRs 对乙酰胆碱的反应，分别为 55±4%和 91±1%。电喷雾质谱表明该毒素的平均分子量为 12358.80 Da。对 hα3β2 nAChRs 的亲和力很高（IC50 为 566.2 nM）。通过自动 Edman 降解获得了一个不含半胱氨酸的部分序列：WFRSFKSYYGHHGSVYRPNEPNFRSFAS…；blastp 搜索表明该序列与一些不含半胱氨酸的 turripeptides 具有低相似性。这是来自美洲太平洋物种的第一个 turritoxin 报告，也是第二个描述抑制 nAChRs 的 turripeptide。
