Probing drug receptor binding sites driven by solid state NMR - An interdisciplinary approach.

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Biology works through highly synchronised chemical interactions at the atomistic scale. Small changes in the electronic charge of a biological molecule, or even the position of a hydrogen atom can have far-reaching consequences (e.g. the very contrasting actions of two subtly different forms (alpha, beta) of thalidomide, or a change of one amino acid in haemoglobin causing sickle cell anaemia). Such subtleties are becoming better understood at the molecular level, but still much is to be discovered and understood for promotion of health and well-being. The major class of targets in disease control for the next ten years is membrane proteins. These are a cell's first point of contact with the outside world and about 85% of all signals to the cell are transmitted through the membrane. It is not surprising then that both academics and drug companies are interested in how such signals are transmitted into the cell (2 Nobel prizes were awarded in 2005 for the revelation that one target membrane protein can activate and signal a multitude of other proteins, depending upon the nature of the small molecule activation, and over 10 Nobel prizes have been awarded for membrane protein studies since 1987). Membrane proteins are very difficult to work with, which is why there are only 21 structures (out of millions available) in the data bases. In addition, we do not have the structure of any ligand-activated human receptor. What we now need is a detailed insight into how these signals are initiated and transmitted at the molecular level, and this can be addressed using nuclear magnetic resonance (NMR) methods designed specifically for probing the detail at very high resolution (better than 0.03 nanometres) and with electronic and dynamic details but, very importantly, in the absence of the total structure of the target receptor protein.Solid state NMR exploits specifically the magnetic properties of some specific atoms for large heterogeneous, non-ordered macromolecules - this has been a fast growing area in structural biology and the UK is at the forefront of the developments. An essential part of this work is the incorporation of magnetic spies (or labels) into the molecule of interest so that we can obtain the information required. The chemical insertion of monitoring nuclei into the information-rich position in the macromolecule is vital and a pre-requisite and can only come from state-of-the-art clever chemistry directed at answering biologically important questions using physical methods. The NMR method is unique in producing very localized and highly specific information at a information-rich site, but this is only possible through the use of highly specialised chemistry to make molecules with the NMR labels where needed - hence this funding application will combine these two areas of expertise (NMR at Oxford and labelling at Bristol) to answer the important biological question How do small molecules activate proteins to transmit signals into a cell? . Detailed information gained will facilitate the understanding of, e.g. how a hormone causes a particular response, or how a toxic chemical initiates cell death. Importantly for wealth creation for the UK, which traditionally has been highly successful in discovering drugs, new design principles will be elucidated.