The structure of a biological system underlies its function. There are many ways to investigate the structure of proteins such as crystallography and NMR. However, these are not always suitable since a protein may be too disordered or large. By adding radical probes ("spin labels") to certain positions in a protein sequence electron paramagnetic resonance (EPR) can be used to find information out about the dynamics of the protein and distances to other probes (using a pulsed EPR method called DEER). These probes can be attached to the same protein or to another, interacting, protein.

By combining the results from EPR with those from other biophysical techniques a picture of the protein or protein complex can be built up. I am developing the use of EPR distance restraints for understanding more about protein structure by applying the method to important biological problems. I work in collaboration with groups from, among others, the Universities of Edinburgh, Leicester and Oxford.

The projects involve all aspects of the work from designing the experiment to molecular biology, sample preparation, measurement, data analysis and interpretation. CW EPR measurements can be made using the spectrometer here and I travel to St Andrew's and Oxford Universities to perform the pulsed EPR experiments.

Figure: General method of research. a) A nitroxide spin label attached to a cysteine in a protein; b) part of the SMRT/NCoR repression complex (TBL1 tetramer in green, salmon and purple, GPS2 in red, HDAC3 in orange and SMRT/NCoR in blue) with illustrated ways that EPR will help determine the relative positioning of these components; c) by combining information from EPR with results from other techniques the structure of very large protein complexes can be built up. Here we have a schematic of the complete 2 MDa SMRT/NCoR repression complex (protein pictures courtesy of Professor John Schwabe, University of Leicester).

SELECTED RECENT PUBLICATIONS

(Lovett née Banham)

1. Ramachandran, P. L., Lovett, J. E., Carl, P. J., Cammarata, M., Lee, J. H., Jung, Y. O., Ihee, H., Timmel, C. R., van Thor, J. J., (2011) The short-lived signaling state of the Photoactive Yellow Protein photoreceptor revealed by combined structural probes. J. Am. Chem. Soc., 133, 9395-9404
2. Lillington, J. E. D., Lovett, J. E., Johnson, S., Roversi, P., Timmel, C. R., Lea, S. M., (2011) Shigella flexineri Spa15 crystal structure verified in solution by double electron electron resonance J. Mol. Biol. 405, 427-435
3. Lovett, J. E., Hoffmann, M., Cnossen, A., Shutter, A. T. J., Hogben, H. J., Warren, J. E., Pascu, S. I., Kay, C. W. M., Timmel, C. R., Anderson, H. L., (2009) Probing flexibility in porphyrin-based molecular wires using double electron electron resonance J. Am. Chem. Soc. 131, 13852–13859
4. Banham, J. E., Baker, C. M., Ceola, S., Day, I. J., Grant, G. H., Groenen, E. J. J., Rodgers, C. T., Jeschke, G., Timmel, C. R., (2008) Distance measurements in the borderline region of applicability of CW EPR and DEER: A model study on a homologous series of spin-labelled peptides J. Magn. Res. 191, 202-218