The functional organisation of a developing light harvesting system

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Nearly all life on Earth gets the food and oxygen it needs to grow from plants or their single celled equivalents the aquatic algae. However, simpler, bacterial photosynthetic organisms live in oceans, lakes and ponds and make a significant contribution to the global food chains. These bacteria are ideal for research as they are easy to grow and study, an essential feature if we are to understand the make up of the proteins ( the tiny biological machines ) that capture light and then convert this into chemical energy that can be used to power the living cell. Our work examines a particular type of protein, a light-harvesting complex (LHC), that can capture light and pass it along a network of identical LHCs to a specialised protein, the reaction centre (RC). The RC protein converts the light energy to chemical energy in the form of a proton gradient - akin to charging up a biological battery. In order to perform their function these proteins must form ordered networks within the cells, but we do not know how this is achieved. We will use a form of imaging known as an atomic force microscope to literally 'feel' the shapes of the LHC and RC proteins as the cell makes networks of them. In this way we will follow the sequence of events that leads to the functional network inside the cells and thus unlock the secret of how nature achieves this feat of bio-engineering.