Development of nanomolar affinity inhibitors of the Yersinia pestis protein-tyrosine phosphatase YopH

Monday, October 24, 2011 — Poster Session I
Noon – 2:00 p.m.	Natcher Conference Center	NCI	BIOCHEM/CHEM-2

* FARE Award Winner

Authors

• M Bahta
• GT Lountos
• B Dyas
• RG Ulrich
• DS Waugh
• TR Burke Jr.

Abstract

The protein-tyrosine phosphatase (PTP), YopH serves as an essential virulence factor for Yersinia pestis, the causative pathogen of plague and a potential bioterrorism agent, and it represents an important yet much less developed therapeutic target. Our current study reports the first KM optimization of a library of nitrophenylphosphate containing substrates to generate a PTP inhibitor lead. A high affinity substrate identified by this method (KM = 80 μM versus KM = 600 μM for parent p-nitrophenylphosphate) was converted from a substrate into an inhibitor by replacement of its phosphate group with the non-hydrolyzable phosphoryl mimetic, difluoromethylphosphonic acid and by attachment of an aminooxy handle for further structural optimization by oxime-ligation. A cocrystal structure of this aminooxy platform in complex with YopH allowed the identification of a conserved water molecule proximal to the ligand aminooxy group that was subsequently employed for the design of furanyl-based oxime derivatives. By this process a non-promiscuous high affinity (IC50 = 190 nM) inhibitor was developed that exhibited good YopH selectivity relative to a panel of phosphatases. The inhibitor showed significant inhibition of intracellular Y. pestis replication at a non-cytotoxic concentration. The current work presents general approaches to PTP inhibitor development that may useful beyond YopH.

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