eIF2B (eukaryotic initiation factor 2B): regulation of its activity and expression, and its roles in translation initiation

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The production of proteins is a key process in all living cells, allowing them to use the genetic information held in the genes in their DNA. Most genes contain the information for making proteins, which are the cellular components that carry out almost all the functions of the cell. To make the protein coded for by a given gene, the letters in the DNA are first copied to a second similar molecule, known as mRNA, in a process called transcription. This mRNA molecule is then 'read' by molecular machines called ribosomes in order to produce the protein, a process known as translation. The proteins expressed within a cell determine its properties, e.g., how it will function and respond to its environment. The process of protein synthesis consumes a large proportion of a cell's energy and nutrients, and so it must be very tightly controlled. Furthermore, this process can be altered to favour the production of different proteins by allowing the machinery to preferentially 'read' certain mRNA molecules, which therefore allows the cell to respond quickly to a stressful environment caused, for example, by a reduction in available nutrients or energy. This kind of mechanism can also control the expression of different proteins as a cell goes through its stages of growth and division, the cell cycle. A key part of the control of protein synthesis involves proteins termed 'initiation factors', which are the focus of this research. These initiation factors control the attachment of the mRNA molecules to ribosomes and are vital to allow protein synthesis to start. They are also a key point of regulation under a wide variety of conditions because they control which mRNA molecules to recruit and even exactly where to start reading their code. The main focus of this research is a factor termed eIF2B, which is composed of 5 separate protein 'subunits'. We will also study two proteins that work with eIF2B in the process of protein synthesis, eIF2 and ABC50. The applicant's laboratory has many years' experience in investigating all these proteins.Disruption of the normal function of eIF2B can lead to disease. Slight spelling mistakes in the genes that encode the 5 subunits of eIF2B lead to an often-serious brain disease, known as 'vanishing white matter'. It also responds to insulin, and so is mis-regulated in type I (insulin-dependent) diabetes. This implies that the proper functioning of eIF2B is necessary to maintain a healthy cell. Furthermore, eIF2B, eIF2 and ABC50 limit the capacity of cells to make proteins that are used as drugs or in disease diagnosis, and which are of great commercial value.We aim to study four main aspects of eIF2B:1. How it is controlled, based on new discoveries made by the applicant's laboratory or others, to learn more about how this important protein can be controlled under different conditions in the cell;2. How cells can control how much of this protein they contain, and how this is related to the control of the amounts of eIF2 and ABC50: this is important as changes in the amounts of all these proteins will affect both how fast proteins can be made and how protein production is controlled;3. How changes in the amounts or the cellular activity of eIF2B (and ABC50) affect the production of specific proteins. This is important since, as described above, changes in protein synthesis have a major affect on how much of different proteins are present in cells, and thus on the function and 'health' of the cell;4. Its structure, using state-of-the-art techniques to investigate the way in which its five subunits are arranged and how they interact with its partner protein, eIF2.