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

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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.