The Integrated Stress Response
The Integrated Stress Response (ISR) is a pro-survival signalling pathway which is present in all eukaryotic organisms in some form or another. The ISR senses certain stresses, such as starvation, or viral infection, tells the cell to stop growing and dividing and instead re-gig its metabolism to combat the stress. It’s often dysregulated in cancers, and aspects of the ISR can mediate very diverse processes such as gut health, memory formation and dietary preferences. We investigate all aspects of the ISR, namely how it is capable of detecting stress, and also how it tailors the cell’s response to each stress – often using a set of tools common to all stresses. We also look at how to develop pharmaceuticals against certain aspects of the ISR.
Transient Molecular Machines
Cellular signalling pathways are often reliant on the formation of very transient nodes of signalling, where large, multi-subunit machines come together to integrate multiple signals into varied responses. These machines are often at important cross-roads in the cell’s life-cycle, whether the grow, whether to divide, or whether to die. Studying these entities is very challenging, and they often exist primarily on paper and are inferred by constructing the necessary components piece-meal by individual investigations. We use structural mass spectrometry, cryo-electron microscopy and other biophysical and structural methods to determine the basis of these machines’ assembly and dismantling.
Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS) is a method that allows the determination of conformational changes that occur in many challenging targets, such as proteins that bind peripherally to membranes, intrinsically disordered proteins, and these large transient molecular machines. HDX-MS examines protein structure and dynamics by measuring the rate at which the protein exchanges hydrogen atoms with the solution in which it is situated. Well-ordered and structured parts of the protein exchange much more slowly than disordered regions, showing us what parts of the protein are folded or otherwise. We also use HDX-MS to discern drug-binding, and to screen drugs for allostery.