Undecaprenyl pyrophosphate synthase (UppS) is an essential enzyme in bacterial cell wall synthesis. Here we report the discovery of Staphylococcus aureus UppS inhibitors from an Encoded Library Technology screen and demonstrate binding to the hydrophobic substrate site through cocrystallography studies. The use of bacterial strains with regulated uppS expression and inhibitor resistant mutant studies confirmed that the whole cell activity was the result of UppS inhibition, validating UppS as a druggable antibacterial target.

Severe α1-antitrypsin deficiency results from the Z allele (Glu342Lys) that causes the accumulation of homopolymers of mutant α1-antitrypsin within the endoplasmic reticulum of hepatocytes in association with liver disease. We have used a DNA-encoded chemical library to undertake a high throughput screen to identify small molecules that bind to, and stabilise Z α1-antitrypsin. The lead compound blocks Z α1-antitrypsin polymerisation in vitro, reduces intracellular polymerisation and increases the secretion of Z α1-antitrypsin three-fold in mammalian cells including an iPSC model of disease. Crystallographic and biophysical analyses demonstrate that GSK716 and related molecules bind to a cryptic binding pocket, negate the local effects of the Z mutation and stabilise the bound state against progression along the polymerization pathway. Oral dosing of transgenic mice at 100 mg/kg three times a day for 20 days increased the secretion of Z α1-antitrypsin into the plasma by 7-fold. There was no observable clearance of hepatic inclusions with respect to controls. This study provides proof-of-principle that ‘mutation ameliorating’ small molecules are a viable approach to treat protein conformational diseases.

Severe α1‐antitrypsin deficiency results from the Z allele (Glu342Lys) that causes the accumulation of homopolymers of mutant α1‐antitrypsin within the endoplasmic reticulum of hepatocytes in association with liver disease. We have used a DNA‐encoded chemical library to undertake a high‐throughput screen to identify small molecules that bind to, and stabilise Z α1‐antitrypsin. The lead compound blocks Z α1‐antitrypsin polymerisation in vitro, reduces intracellular polymerisation and increases the secretion of Z α1‐antitrypsin threefold in an iPSC model of disease. Crystallographic and biophysical analyses demonstrate that GSK716 and related molecules bind to a cryptic binding pocket, negate the local effects of the Z mutation and stabilise the bound state against progression along the polymerisation pathway. Oral dosing of transgenic mice at 100 mg/kg three times a day for 20 days increased the secretion of Z α1‐antitrypsin into the plasma by sevenfold. There was no observable clearance of hepatic inclusions with respect to controls over the same time period. This study provides proof of principle that “mutation ameliorating” small molecules can block the aberrant polymerisation that underlies Z α1‐antitrypsin deficiency.

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