Characterising a critical role for novel glycosphingolipids in the mechanism of action of insecticidal Toxin_10 proteins

蚊子是人类疾病的主要携带者，包括寨卡病毒、疟疾和西尼罗河热。没有多少安全的杀虫剂可以用来杀死蚊子，而不会对环境或人类健康造成损害。为数不多的可用毒素之一是Bin毒素，它是由一种特殊类型的细菌Lysinibacillus sphaericus制成的，可以杀死蚊子幼虫。然而，蚊子正在对这种毒素产生抵抗力。至关重要的是，我们要找出Bin毒素是如何杀死蚊子的，这样才能使它更有效，或者找到替代品。关于Bin毒素是如何杀死蚊子的，我们知之甚少。我们知道它与蚊子幼虫肠道中的一种特殊蛋白质结合。毒素与这种蛋白质的结合导致蚊子肠道细胞的变化-毒素被吸收到肠道细胞中，导致肠道细胞内形成大气泡，不知何故，这导致肠道细胞死亡，然后蚊子死亡。Bin毒素有两个部分，BinA和BinB，BinB与蚊子肠道中的蛋白质结合，但这两个部分都是杀死蚊子所必需的。BinA和BinB都是毒素家族的一部分，称为Toxin_10。这种毒素家族在某些方面与结合糖的蛋白质相似，特别是与脂质（脂肪）连接的糖。我们已经知道有几种毒素利用它们的能力结合（粘附）这些糖修饰的脂肪，以便进入脂肪组织，然后一旦它们进入体内就杀死它们的靶细胞。这些包括霍乱和破伤风中的毒素。我们有证据表明Bin毒素也能与一种糖修饰的脂肪结合，我们称之为“糖脂”，但我们还不知道是哪一种。我们的目标是发现Bin毒素与哪种糖脂结合，以及这是否对Bin毒素能够在细胞内形成气泡并杀死蚊子很重要。我们还将发现Bin毒素蛋白的哪些确切部分负责结合糖脂，以及在这些区域进行改变是否会改变Bin毒素结合糖脂或杀死蚊子的能力，这可能有助于制造更有效的杀虫剂。Bin毒素所属的Toxin_10家族的其他成员杀死不同的昆虫，其中几种是经济上重要的农业害虫。对当前杀虫剂的抗性也是农业中的一个主要问题，迫切需要控制这些害虫的替代方法。这些毒素_10家族成员之一是Cry 35，它可以杀死西方玉米根虫，这是美国玉米生产中的一个主要问题。我们将研究Cry 35是否像Bin毒素一样也结合糖脂，如果是的话，这是否对其杀死西方玉米根虫的能力很重要。这项研究有可能发现毒素10是如何杀死昆虫的。有了这些信息，我们也许能够使它们成为更有效的杀虫剂，从而减少蚊媒疾病的传播和农业对化学杀虫剂的依赖。

Mosquitoes are major carriers of human diseases, including Zika virus, malaria and west Nile fever. There are not many safe insecticides available to kill mosquitoes that are not damaging to the environment or human health. One of the few available is Bin toxin, which is made by a particular type of bacteria called Lysinibacillus sphaericus, which kills mosquito larvae. However, mosquitoes are developing resistance to the toxin. It is vital that we find out how Bin toxin kills mosquitoes so that it can be made more effective or that alternatives can be identified. Not much is known about how Bin toxin kills mosquitoes. We know it binds to a particular protein in the gut of mosquito larvae. Binding of the toxin to this protein causes changes in the cells in the mosquito gut - the toxin is taken into cells of the gut causing large bubbles to form inside them and somehow this leads to death of cells in the gut and then death of the mosquito. Bin toxin has two parts, BinA and BinB, it is BinB that binds to the protein in the mosquito gut but both parts are needed to kill mosquitoes. Both BinA and BinB are part of a family of toxins called Toxin_10. This toxin family are similar in certain ways to proteins that bind sugars, especially sugars which are attached to lipids (fats). Several toxins are already known to us that use their ability to bind (stick to) these sugar modified fats in order to gain entry into cels and then kill their target cells once they are inside. These include the toxins involved in cholera and tetanus. We have evidence that Bin toxin also binds to one of these sugar modified fats, which we call "glycolipids", but we don't know which one yet. We aim to discover exactly which glycolipid Bin toxin binds to, and whether this is important for Bin toxin to be able to cause bubble formation inside cells and kill mosquitoes. We will also discover which exact parts of the Bin toxin proteins are responsible for binding the glycolipid, and whether making alterations in these areas changes the ability of Bin toxin to bind glycolipid or kill mosquitoes, which may help make a more effective insecticide. Other members of the Toxin_10 family that Bin toxin belongs to kill different insects, several of which are economically important agricultural pests. Resistance to current pesticides is also a major problem in agriculture, and there is a pressing need for alternative methods to control these pests. One of these Toxin_10 family members is Cry35, which kills the Western corn root worm, a major problem in maize production in the USA. We will investigate whether Cry35, like Bin toxin, also binds a glycolipid and, if it does, whether this is important for its ability to kill Western corn root worm. This research has the potential to find out how Toxin_10 toxins are killing insects. With this information, we may be able to make them more effective pesticides, thus reducing the spread of mosquito-borne disease and agricultural reliance on chemical pesticides.