Structure and function of SRA domains implicated in chromatin regulation

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In a multi-cellular organism all cells inherit the same genetic information in the form of DNA. The information in the DNA is typically decoded to make proteins or RNA. As the organism develops some cells will decode particular DNA sequences (genes) into proteins and RNA, whilst other cells will not. In recent years a great deal has been learnt about the different molecules, which are involved in carrying out this process. Typically, specific proteins bind near the beginning of a particular DNA sequence (gene) to initiate the decoding; these proteins are called transcription factors and they recognise and bind to particular genes. However, the DNA within the cell is packaged in bundles with structural proteins (called histones). Recently, it has become clear that this packaging can be controlled by proteins in a gene-specific manner. We suspect that the packaging of the DNA can lead to particular sequences being hidden away inside a complex structure so that decoding no longer occurs. This may be likened to reading a book where what can be read is controlled by whatever opens the book at particular pages. Several mechanisms for the control of this 'page reading' are now being studied very intensively. We aim to study a class of proteins that are in some way involved in the regulation of gene transcription at this level of DNA packaging. How they work is not yet clear, but the studies that we have carried out so far have provided a hypothesis from which we can begin to explore further. An important feature of the class of proteins we intend to study is that they interact with many partners to form a fully functional protein complex. We are planning to determine the structure of a particular building block (a protein domain) and then study how it interacts with key partner proteins. Using this information we will then carry out further experiments designed to follow directly the interactions in vivo and establish how this domain functions within the complex to regulate DNA packaging.