Structural basis for the selective binding of inhibitors to 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase from Staphylococcus aureus and Escherichia coli

Matthew L. Dennis, Noel P. Pitcher, Michael D. Lee, Aaron J. Debono, Zhong-Chang Wang, Jitendra R. Harjani, Raphaël Rahmani, Ben Cleary, Thomas S. Peat, Jonathan B. Baell, James D. Swarbrick

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6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a member of the folate biosynthesis pathway found in prokaryotes and lower eukaryotes that catalyzes the pyrophosphoryl transfer from the ATP cofactor to a 6-hydroxymethyl-7,8-dihydropterin substrate. We report the chemical synthesis of a series of S-functionalized 8-mercaptoguanine (8MG) analogues as substrate site inhibitors of HPPK and quantify binding against the E. coli and S. aureus enzymes (EcHPPK and SaHPPK). The results demonstrate that analogues incorporating acetophenone-based substituents have comparable affinities for both enzymes. Preferential binding of benzyl-substituted 8MG derivatives to SaHPPK was reconciled when a cryptic pocket unique to SaHPPK was revealed by X-ray crystallography. Differential chemical shift perturbation analysis confirmed this to be a common mode of binding for this series to SaHPPK. One compound (41) displayed binding affinities of 120 nM and 1.76 μM for SaHPPK and EcHPPK, respectively, and represents a lead for the development of more potent and selective inhibitors of SaHPPK.

Original languageEnglish
Pages (from-to)5248-5263
Number of pages16
JournalJournal of Medicinal Chemistry
Issue number11
Publication statusPublished - 9 Jun 2016

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