Roger Williams

Roger Williams

Mechanisms of regulation of nutrient-sensitive kinases
Group Leader page

You will join a research programme aimed at establishing fundamental molecular mechanisms of cellular homeostasis. The protein kinase GCN2 initiates the integrated stress response (ISR) as a consequence of nutritional stress. The consequence of this is that general protein synthesis is restricted, while there is an increase in translation of stress response transcripts. When amino acids are in insufficient supply, the cell begins a catabolic process known as autophagy that can digest cytoplasmic contents to supply amino acid building blocks for protein synthesis. Autophagy is controlled by a large complex of proteins that includes the lipid kinase VPS34. In contrast to VPS34 and GCN2 that are activated by starvation of amino acids, the protein kinase mTOR is part of a protein complex that is activated when nutrition is plentiful. The regulations of these three enzymes are intricately tied to each other.

The project involves electron cryo-microscopy (cryo-EM) of ribosomal complexes with GCN2, the cryo-EM structures of VPS34- and mTOR-containing complexes on membranes and characterisation of the dynamics of the complexes by hydrogen/deuterium exchange mass spectrometry (HDX-MS) and enzyme kinetics. Work in the group has developed HDX-MS analysis of protein/protein and protein/membrane interactions to an unprecedented level. This powerful technique has been applied to precisely map interactions within even very large complexes, such as GCN2 interacting with the 80S ribosome. An important dimension of the project is that you will become adept at both cryo-EM and HDX-MS. In addition, it is likely that some aspects of the project will involve X-ray crystallography.


References

Ishimura, R., Nagy, G., Dotu, I., Chuang, J.H., and Ackerman, S.L. (2016).
Activation of GCN2 kinase by ribosome stalling links translation elongation with translation initiation.
Elife 5, e14295.

Rostislavleva, K., Soler, N., Ohashi, Y., Zhang, L., Pardon, E., Burke, JE, Masson, GR, Johnson, C., Jan Steyaert, J., Ktistakis, NT, Williams, RL. (2015)
Structure and flexibility of the endosomal Vps34 complex reveals the basis of its function on membranes.
Science 350:aac7365. PMID 2645021

Yang, H., Jiang, X., Li, B., Yang, H.J., Miller, M., Yang, A., Dhar, A., and Pavletich, N.P. (2017).
Mechanisms of mTORC1 activation by RHEB and inhibition by PRAS40.
Nature 552, 368–373.