A fragment-based drug discovery approach targeting human UDP-galactose-4-epimerase
File(s)
Author(s)
Browne, William
Type
Thesis
Abstract
O-GalNAc glycosylation is a ubiquitous post translational modification and plays a crucial role in a variety of inter- and intracellular processes. However, our understanding of the precise mechanisms by which O-GalNAc glycans act is still limited, in part due to a lack of appropriate chemical tools. Mucins are a family of heavily O-GalNAc glycosylated glycoproteins that have pro-tumorigenic properties and are thus a well validated therapeutic target. Essential to the function and expression of mucins are their characteristic dense array of O-GalNAc glycans. A small molecule inhibitor of O-GalNAc glycosylation will provide a useful chemical tool for the study of glycans and may offer a novel method of therapeutic intervention against mucin expressing cancers.
The enzyme UDP-Galactose-4-epimerase (GALE) is required for the biosynthesis of the essential O-GalNAc glycosylation precursor UDP-GalNAc. A small molecule inhibitor of GALE would thus inhibit the O-GalNAc biosynthetic pathway and subsequent glycosylation. Therefore, this manuscript describes the screening and optimisation of a GALE inhibitor using a fragment-based drug discovery approach. Non-covalent fragment screening was performed with cutting edge crystallographic screening. An initial hit fragment was elaborated using structure guided design to a nanomolar binder and low micromolar inhibitor. In parallel, covalent fragment screening has been used to validate GALE as tractable by covalent molecules. With this validation, a ligand first approach was used to develop a covalent inhibitor of GALE from the identified non-covalent fragment binders.
In summary, two small molecule lead inhibitors of GALE with orthogonal mechanisms of inhibition have been developed towards GALE. Providing a robust starting point from which to develop tool compounds suitable for application in cells.
The enzyme UDP-Galactose-4-epimerase (GALE) is required for the biosynthesis of the essential O-GalNAc glycosylation precursor UDP-GalNAc. A small molecule inhibitor of GALE would thus inhibit the O-GalNAc biosynthetic pathway and subsequent glycosylation. Therefore, this manuscript describes the screening and optimisation of a GALE inhibitor using a fragment-based drug discovery approach. Non-covalent fragment screening was performed with cutting edge crystallographic screening. An initial hit fragment was elaborated using structure guided design to a nanomolar binder and low micromolar inhibitor. In parallel, covalent fragment screening has been used to validate GALE as tractable by covalent molecules. With this validation, a ligand first approach was used to develop a covalent inhibitor of GALE from the identified non-covalent fragment binders.
In summary, two small molecule lead inhibitors of GALE with orthogonal mechanisms of inhibition have been developed towards GALE. Providing a robust starting point from which to develop tool compounds suitable for application in cells.
Version
Open Access
Date Issued
2023-11-16
Date Awarded
2024-02-01
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Schumann, Benjamin
Bush, Jacob
Sponsor
Engineering and Physical Sciences Research Council
GlaxoSmithKline
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)