Exploring magnetically aligned bilayers as a novel tool for membrane protein crystallisation

膜嵌入蛋白（或膜蛋白）是最具影响力的生存，正确的行为和细胞的功能。它们形成了细胞与环境相互作用的方式，通过它们输入营养物质并排出潜在的有毒分子，并相互交流。在人类中，膜蛋白几乎占所有已知蛋白质的三分之一，目前可用的药物中有一半以上作用于膜蛋白。因此，研究膜蛋白的作用及其功能是学术研究科学家和制药行业共同的追求。研究蛋白质的作用和功能的一种有力手段是将它们的三维形状可视化，并提供足够的细节来区分单个化学基团和原子。这种分析使我们能够像观察一台机器一样了解每种蛋白质成分的作用，并设想协助或破坏其机制的方法，然后将其转化为药物和疾病治疗方法。x射线晶体学是我们在这种细节水平上可视化蛋白质的首要方法；然而，这种方法需要形成高度有序的晶体，其中蛋白质分子以可预测和规则的方式相互堆积。由于膜蛋白需要从其天然膜环境中提取才能结晶，因此它们经常受到破坏，因此不易形成晶体。正是由于这个原因，尽管膜蛋白在生物体中非常重要，但在已知详细形状的蛋白质中，膜蛋白只占很小的比例，不到2%。因此，开发诱导膜蛋白形成晶体的新工具可以极大地扩展我们对细胞机制的详细了解。传统上，膜蛋白被分离出来，并在肥皂样洗涤剂分子的存在下处理；然而，这种洗涤剂使蛋白质不太可能正常发挥作用或形成晶体。由于这个原因，研究人员一直在开发先进的方法，在结晶过程中为蛋白质提供更像膜的环境，例如，通过添加类似于细胞膜中的脂质。当膜蛋白通过这些方法结晶时，晶体通常由自发形成的脂质双层堆叠组成，这种排列与蛋白质在活细胞膜中遇到的情况有些相似。在这个提议中，我们的目标是开发一种新方法，帮助膜蛋白在这种堆叠的脂质双层中有规则地包装，从而增加它们形成晶体的可能性。为了做到这一点，我们将利用强超导磁体，众所周知，它通过迫使膜的方向跟随磁场的方向来施加膜的秩序。我们假设，通过这种方式，膜上的蛋白质也将被迫向特定方向移动，这种空间限制可能会导致它们更容易打包成晶体。如果这种磁性排列结晶（“MAX”）方法证明是成功的，我们的目标是进一步发展磁铁在膜蛋白结晶中的应用，使其成为学术界和工业界广泛使用的工具。

Membrane-embedded proteins (or membrane proteins) are amongst the most influential for the survival, correct behaviour and function of cells. They form the means by which cells interact with their environments, by which they import nutrients and expel potentially poisonous molecules, and communicate with each other. In humans, membrane proteins comprise almost a third of all known proteins, and over half of the currently available drugs act on membrane proteins. Thus, studying the roles of membrane proteins and how they function is a pursuit shared by both academic research scientists and the pharmaceutical industry alike.A powerful means for studying the role and function of proteins is visualising their three-dimensional shape with enough detail to distinguish individual chemical groups and atoms. Such analysis allows us to understand the purpose of each protein component as if we were observing a machine, and to envision ways of assisting or disrupting its mechanism that can then be translated into drugs and therapies for diseases. X-ray crystallography is the premier method by which we visualise proteins at this level of detail; however, this method requires the formation of highly ordered crystals where protein molecules pack against each other in a predictable and regular manner. Due to the fact that membrane proteins need to be extracted from their natural membrane environment in order to be crystallised, they are often damaged and therefore they do not easily form crystals. It is for this reason that, despite their enormous importance in living organisms, membrane proteins make up a very small proportion, less than 2%, of proteins for which the detailed shape is known. Thus, developing novel tools that induce membrane proteins to form crystals could tremendously expand our detailed understanding of cellular mechanisms.Traditionally, membrane proteins were isolated and handled in the presence of soap-like detergent molecules; however, such detergents make the proteins less likely to function correctly or to form crystals. For this reason, researchers have been developing advanced methods that provide a more membrane-like environment for the proteins during crystallisation, e.g. by the addition of lipids that are similar to those in the cell membrane. When membrane proteins do crystallise through these methods the crystals often consist of spontaneously formed stacks of lipid bilayers, an arrangement that vaguely resembles the situation the protein would encounter in the membrane of a living cell. In this proposal we aim to develop a new method that assists the regular packing of membrane proteins in such stacked lipid bilayers, and thereby increases the probability that they form crystals. To do so we will utilise strong superconducting magnets, which are known to impose order in membranes by forcing their orientation to follow the direction of the magnetic field. We hypothesise that in this way membrane-embedded proteins will also be forced toward a particular direction, and this spatial restriction may induce them to pack more readily into crystals. Should this magnetic alignment crystallisation ('MAX') approach prove successful, we aim to further develop the use of magnets in the crystallisation of membrane proteins into a tool widely available in the academic community and industry.