STRUCTURE AND FUNCTION OF PROTEINS IMPLICATED IN NEURODEGENERATION
Our goal is to understand how proteins implicated in recessive forms of Parkinson's disease (PD) normally protect neurons, and how they are inactivated in PD. Our approach consists of elucidating their structures using a wide-range of techniques such as X-ray crystallography, nuclear magnetic resonance and mass spectrometry. The 3D structures obtained will be used to understand the mode of action of these proteins. Moreover, these structures can be used as scaffolds for designing new drugs that will enhance their activity and therefore could help slow down or even stop the degeneration of neurons causing PD.
We use mass spectrometry to determine how proteins are modified, either by phosphorylation, ubiquitination, or proteolysis. As the co-director of the Pharmacology SPR-MS unit (https://www.mcgill.ca/pharma/core-facilities), Dr Trempe supervises the operation of a Bruker Impact II Q-TOF, coupled to a Dionex 3000 HPLC (CFI 2014). We routinely analyze intact proteins, resolved on a C4 reverse-phase column, as well as tryptic digests on a C18 nano-column, which we use to characterize protein phosphorylation. Since Feb 2020, Dr Trempe is the Scientific Director of the Proteomics platform at the Research Institute of the McGill University Health Centre (https://rimuhc.ca/clinical-proteomics).
To understand how proteins function, we use biophysical methods such as NMR spectroscopy X-ray crystallography to solve the 3D structure of proteins, which reveal how they catalyze reactions or interact with each other.
STRUCTURE AND FUNCTION OF PINK1
Mutations in PINK1 causes autosomal recessive Parkinson's disease. The protein is a mitochondrial kinase that phosphorylates ubiquitin. We published a biophysical analysis of PINK1, which revealed how the protein binds ubiquitin, and how it must auto-phosphorylate in trans in order to recognize ubiquitin (Rasool et al, EMBO Rep, 2018).
More recently, we have solved the structure of PINK1 in its dimeric form (movie on the left, PDB 7MP9). The structure reveals the mechanism of PINK1 activation via autophosphorylation, and provide insights into binding to the TOM complex on mitochondria (Rasool et al, Mol Cell, 2021).
FINDING NEW PARKIN ACTIVATORS
Loss of Parkin activity cause early-onset familial PD through inherited mutations. Numerous studies have shown that Parkin activity is neuroprotective in cell and animal models of PD. Based on structural studies, we have demonstrated that mutation of W403 increase Parkin’s activity in cells (Trempe et al. 2013), and can rescue inactive and PD mutations (Tang et al 2017; Yi et al 2019). We have discovered fragment molecules that mimic the indole side-chain of W403 and bind selectively to Parkin, and we are developing them into small molecule activators of Parkin.