Touchard Axel, Mendel Helen C, Boulogne Isabelle, Herzig Volker, Braga Emidio Nayara, King Glenn F, Triquigneaux Mathilde, Jaquillard Lucie, Beroud Rémy, De Waard Michel, Delalande Olivier, Dejean Alain, Muttenthaler Markus, Duplais Christophe
CNRS, UMR Ecofog, AgroParisTech, Cirad, INRAE, Université des Antilles, Université de Guyane, Kourou 97310, France.
Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia.
ACS Pharmacol Transl Sci. 2020 Oct 6;3(6):1211-1224. doi: 10.1021/acsptsci.0c00119. eCollection 2020 Dec 11.
Ants use venom for predation, defense, and communication; however, the molecular diversity, function, and potential applications of ant venom remains understudied compared to other venomous lineages such as arachnids, snakes and cone snails. In this work, we used a multidisciplinary approach that encompassed field work, proteomics, sequencing, chemical synthesis, structural analysis, molecular modeling, stability studies, and and bioassays to investigate the molecular diversity of the venom of the Amazonian ants. We isolated a potent insecticidal heterodimeric peptide Δ-pseudomyrmecitoxin-Pp1a (Δ-PSDTX-Pp1a) composed of a 27-residue long A-chain and a 33-residue long B-chain cross-linked by two disulfide bonds in an antiparallel orientation. We chemically synthesized Δ-PSDTX-Pp1a, its corresponding parallel AA and BB homodimers, and its monomeric chains and demonstrated that Δ-PSDTX-Pp1a had the most potent insecticidal effects in blowfly assays (LD = 3 nmol/g). Molecular modeling and circular dichroism studies revealed strong α-helical features, indicating its cytotoxic effects could derive from cell membrane pore formation or disruption. The native heterodimer was substantially more stable against proteolytic degradation ( = 13 h) than its homodimers or monomers ( < 20 min), indicating an evolutionary advantage of the more complex structure. The proteomic analysis of venom and in-depth characterization of Δ-PSDTX-Pp1a provide novel insights in the structural complexity of ant venom and further exemplifies how nature exploits disulfide-bond formation and dimerization to gain an evolutionary advantage via improved stability, a concept that is highly relevant for the design and development of peptide therapeutics, molecular probes, and bioinsecticides.
蚂蚁利用毒液进行捕食、防御和交流；然而，与蜘蛛、蛇和芋螺等其他有毒谱系相比，蚂蚁毒液的分子多样性、功能及潜在应用仍未得到充分研究。在这项研究中，我们采用了多学科方法，包括野外工作、蛋白质组学、测序、化学合成、结构分析、分子建模、稳定性研究和生物测定，以探究亚马逊蚂蚁毒液的分子多样性。我们分离出一种强效杀虫异源二聚体肽Δ-拟切叶蚁毒素-Pp1a（Δ-PSDTX-Pp1a），它由一条27个残基长的A链和一条33个残基长的B链组成，两条链通过两个反平行方向的二硫键交联。我们化学合成了Δ-PSDTX-Pp1a、其相应的平行AA和BB同二聚体及其单体链，并证明在蝇类试验中Δ-PSDTX-Pp1a具有最强的杀虫效果（半数致死剂量=3 nmol/g）。分子建模和圆二色性研究揭示了其强烈的α-螺旋特征，表明其细胞毒性作用可能源于细胞膜孔的形成或破坏。天然异二聚体比其同二聚体或单体对蛋白水解降解的稳定性要高得多（半衰期=13小时），而其同二聚体或单体的半衰期<20分钟，这表明更复杂结构具有进化优势。对蚂蚁毒液的蛋白质组学分析以及对Δ-PSDTX-Pp1a的深入表征，为蚂蚁毒液的结构复杂性提供了新的见解，并进一步例证了自然界如何利用二硫键形成和二聚化，通过提高稳定性获得进化优势，这一概念与肽类治疗药物、分子探针和生物杀虫剂的设计与开发高度相关。
