Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
Toxicon. 2022 Oct 30;218:40-46. doi: 10.1016/j.toxicon.2022.09.003. Epub 2022 Sep 9.
Txp40 is a ubiquitous toxin from Xenorhabdus and Photorhabdus bacteria, exhibits insecticidal activity against a wide range of insect pests belonging to Lepidoptera and Diptera orders. Initially, Txp40 affects midgut of the target insect and further damages some other tissues like fat bodies but the detailed mode of action is not known. Txp40 shares no significant sequence match to any proteins with known structure or function, suggesting that it is a novel type of insecticidal toxin. Here, we report purification, toxicity and biophysical characterization of the Txp40b toxin from X. nematophila (ATCC, 19061). The recombinant Txp40b was found toxic to Galleria mellonella larvae with LD of 30.42 ng larva. Circular dichroism spectroscopy revealed that purified Txp40b is an α-helix rich protein with a relatively lower melting temperature of 45 °C. In-silico model generated suggests two domain structure of Txp40b toxin. Detailed structural analysis of Txp40b will provide new insights about the mode of action and possibly it would illustrate a new domain and/or motif in the area of insecticidal proteins.
Txp40 是一种普遍存在的 Xenorhabdus 和 Photorhabdus 细菌毒素，对鳞翅目和双翅目昆虫的多种害虫具有杀虫活性。最初，Txp40 会影响目标昆虫的中肠，进一步损害脂肪体等其他一些组织，但详细的作用模式尚不清楚。Txp40 与任何具有已知结构或功能的蛋白质都没有显著的序列匹配，这表明它是一种新型的杀虫毒素。在这里，我们报告了来自 X. nematophila (ATCC, 19061) 的 Txp40b 毒素的纯化、毒性和生物物理特性。重组的 Txp40b 对家蚕幼虫具有毒性，LD 为 30.42ng 幼虫。圆二色性光谱显示，纯化的 Txp40b 是一种富含 α-螺旋的蛋白质，其相对较低的熔点为 45°C。计算模型表明 Txp40b 毒素具有两个结构域。对 Txp40b 的详细结构分析将提供关于作用模式的新见解，并且可能会在杀虫蛋白领域说明一个新的结构域和/或基序。
