Unravelling the organisation, composition and dynamics of the plant cellulose synthase complex

纤维素是许多植物细胞壁的主要成分，被认为是世界上最丰富的天然聚合物，是我们周围自然世界的主要成分。木材由植物细胞壁组成，特别高比例（高达70%）的木材由纤维素组成。纤维素在确定作物植物的机械性质方面也很重要，因此在防止谷物和其他作物倒伏（倒伏）方面也很重要。对于工业而言，次级壁的性能直接决定了所制造产品的性能，例如纸张质量和纺织品中使用的纤维。此外，我们迫切需要增加可生物降解的原材料比例，这可以通过在材料中使用天然植物纤维而不是合成纤维来满足，例如人造玻璃。由于使用化石燃料（例如汽油），加上全球化石燃料储量减少，全球变暖及其与碳排放量增加的联系引起了人们对寻找不会导致CO2浓度增加且可持续的替代燃料源的巨大兴趣。一个潜在的来源是使用生物材料，“生物燃料”。一种可能性是用纤维素制造乙醇或其他燃料，就像巴西使用甘蔗中的糖一样。虽然纤维素非常丰富，但使用纤维素存在一些技术挑战，包括将其与细胞壁的其他部分分离，打破其牢固的结合结构以及如何让植物产生更多的纤维素。令人惊讶的是，纤维素的巨大重要性并没有与对其形成背后的过程的同等理解相匹配。我们知道一些组成植物纤维素合成机制的成分，称为纤维素合成酶复合物，它存在于细胞表面的脂膜中，但我们不知道这些成分存在于机制中的何处，也不知道每个成分如何有助于制造纤维素。膜蛋白特别难以研究，因为为了使它们可溶，有时需要添加苛刻的洗涤剂，这些洗涤剂也会破坏蛋白质之间的相互作用。一种替代方法是在使用洗涤剂之前将蛋白质化学交联在一起，但如果复合物中的大量蛋白质都结合在一起，这可能会变得复杂。为了简化这个问题，我们已经修改了其中一种蛋白质，这样我们现在就可以看到蛋白质不同部分形成交联的潜力。通过分别观察每个区域，它应该简化分析，并告诉我们不同的蛋白质在哪里相互结合。利用这些信息，我们将了解制造纤维素的整个蛋白质复合物是如何组织的。这很重要，因为正是这种复合物的组织决定了纤维素微纤丝的结构。我们还将使用最近开发的技术，使我们能够标记蛋白质结合，或接近其天然环境中的纤维素合酶复合物的成分。通过将这些结果与研究不同细胞类型中纤维素合成所获得的结果进行比较，将使我们能够帮助区分哪些是制造纤维素所需的基本核心组分，哪些是可能仅短暂结合的核心组分，并且可能涉及在细胞周围移动的复合物的定位。最终，这项工作应该提供一个框架，我们可以使用它来进行可能改变纤维素性质的改变它所产生的。已经知道，一些突变降低了纤维素的结晶度，因此使其更容易分解为可能用于生物燃料或其他工业应用的组成糖。这项工作应该提供关于如何进行更大幅度改进的重要信息。

Cellulose is the major component of many plant cells walls and is considered to be the world's most abundant naturally occurring polymer and is a major component of the natural world all around us. Wood is composed of plant cell walls and a particularly high proportion (up to 70%) of wood is made up of cellulose. Cellulose is also important in determining the mechanical properties of crop plants and consequently important in preventing cereals and other crops from falling over (lodging). For industry, the properties of the secondary walls directly determine the properties of the manufactured products, for example paper quality and the fibres used in textiles. Additionally, the pressing need to increase the proportion of our raw materials that are biodegradable can be filled by using natural plant fibres instead of synthetic fibres in materials such as fibreglass. Global warming and its links to rising carbon emissions, due to the use of fossil fuels, such as petrol, coupled with diminishing worldwide fossil fuel reserves has generated a huge interest in finding alternative fuel sources that do not contribute to increases in CO2 concentrations and are sustainable. One potential source is to use biological material, "biofuels". One possibility is to use cellulose to make ethanol or other fuels in the same way that sugar from cane has been used in Brazil. Although cellulose is very abundant there are several technological challenges associated with using cellulose, including separating it from other parts of the cell wall, breaking up its strongly bonded structure and how to get plants to make more cellulose. Surprisingly, the vast importance of cellulose is not matched by an equal understanding of the processes behind its formation. We know some of the components that make up the plant's cellulose synthesising machinery, termed the cellulose synthase complex, which resides in lipid membranes at the cells surface, but we don't understand where in the machinery these components reside nor how each component contributes to making cellulose. Membrane proteins are particularly hard to study as to make them soluble it is sometimes necessary to add harsh detergents that also break up interaction between proteins. One alternative is to chemically crosslink the proteins together before using detergents, but this can become complicated to unravel if large numbers of proteins in complex all become bound together. To simplify this problem we have modified one of the proteins such that we will now be able to look at the potential of different parts of the protein to form crosslinks. By looking at each region separately, it should simplify the analysis and also tells us where different proteins bind to one another. Using this information we will get an idea of how the entire protein complex that makes cellulose is organised. This is important because it is the organisation of this complex that determines the structure of the cellulose microfibril. We will also use a recently-developed technique that allows us to label proteins that bind to, or are close to components of the cellulose synthase complex in their native environment. By comparing these results with those obtained from studying cellulose synthesis in different cell types will enable us to help distinguish what are essential core components required to make cellulose from those that may only bind transiently and may be involved in localisation of the complex of in moving it around the cell.Ultimately this work should provide a framework that we can use to make changes that may alter the properties of the cellulose that it produces. It is already known that some mutations reduce the crystalinity of the cellulose and so makes it easier to breakdown into its constituent sugars that maybe used for biofuel or other industrial applications. This work should provide important information about how to make much more dramatic improvements.