Fragment based drug discovery for SOD1-ALS and solution X-ray scattering studies on the copper chaperone for SOD1 (hCCS)and its functional complexes with SOD1

Wright, Gareth
Fragment based drug discovery for SOD1-ALS and solution X-ray scattering studies on the copper chaperone for SOD1 (hCCS)and its functional complexes with SOD1. Doctor of Philosophy thesis, University of Liverpool.

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Amyotrophic lateral sclerosis (ALS) is a fatal disease of the nervous system. The majority of ALS cases are have no attributable genetic link, however approximately 10% are familial and 20 % of these result from mutations in the SOD1 gene. How SOD1 mutation manifests as the ALS phenotype is not clear however the enzyme does gain an aggregative property characterised by SOD1 inclusions in the brain and spinal cord. Drug treatment for sporadic and familial ALS is currently limited to palliatives and there is currently no specific treatment for SOD1 mediated ALS. In order to find molecules that may be of use in the development of SOD1 therapeutics a crystallographic screening pipeline was set up to assess binding of small molecules to both wild-type and SOD1 mutants. Using in silico studies and previous crystallographic work as a starting point, this method revealed several low molecular weight compounds (Mr 183 – 310 gMol-1) that have SOD1 binding activity. These molecules belong to three distinct classes: catecholamine, quinazoline and fluorouridine and occupy two distinct binding sites on the surface of the SOD1 β-barrel in an area known to be important in disease pathogenesis. The incorporation of copper into biological macromolecules such as SOD1 is essential for the viability of most organisms. However, copper is toxic and therefore the intracellular free copper concentration is kept to an absolute minimum. The Copper Chaperone for SOD1 (CCS) is the major pathway for SOD1 copper loading and transfer of an intrasubunit disulphide bond known to stabilise SOD1. Using small angle X-ray scattering combined with online size exclusion chromatography high quality data were acquired for both homodimeric hCCS and the functionally critical hCCS-SOD1 heterodimer. SAXS measurements were made of the hCCS complex with wild-type SOD1 and the disease relevant L38V and I113T SOD1 mutants. A rigid body modelling approach enabled exploration of the conformational dynamics of each species. Homodimeric hCCS is found to adopt positions that would facilitate initial copper acquisition and transfer from domain I to domain III. This domain III is also found in positions that would allow disulphide and copper transfer to SOD1 in the heterodimeric complex. The hCCS-I113T SOD1 complex has characteristics which are convergent with a view of ALS initiated by improperly matured SOD1.

Item Type: Thesis (Doctor of Philosophy)
Additional Information: Date: 2011-11 (completed)
Uncontrolled Keywords: SOD1, SAXS, crystallography, drug discovery
Divisions: Faculty of Health and Life Sciences
Depositing User: Symplectic Admin
Date Deposited: 07 Aug 2012 08:34
Last Modified: 16 Dec 2022 04:36
DOI: 10.17638/00005473
  • Hasnain, Samar
  • Strange, Richard