Multiple binding modes of isothiocyanates that inhibit macrophage migration inhibitory factor.
Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that has roles in the innate immune response, and also contributes to inflammatory disease. While the biological properties of MIF are closely linked to protein-protein interactions, MIF also has tautomerase activity. Inhibition of this activity interferes with the interaction of MIF with protein partners e.g. the CD74 receptor, and tautomerase inhibitors show promise in disease models including multiple sclerosis and colitis. Isothiocyanates inhibit MIF tautomerase activity via covalent modification of the N-terminal proline. We systematically explored variants of benzyl and phenethyl isothiocyanates, to define determinants of inhibition. In particular, substitution with hydroxyl, chloro, fluoro and trifluoro moieties at the para and meta positions were evaluated. In assays on treated cells and recombinant protein, the IC50 varied from 250 nM to >100 μM. X-ray crystal structures of selected complexes revealed that two binding modes are accessed by some compounds, perhaps owing to strain in short linkers between the isothiocyanate and aromatic ring. The variety of binding modes confirms the existence of two subsites for inhibitors and establishes a platform for the development of potent inhibitors of MIF that only need to target one of these subsites.
Centre for Free Radical Research, Department of Pathology, University of Otago, PO Box 4345, Christchurch 8140, New Zealand.
Emma S
ES
Spencer
Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Edward J
EJ
Dale
Department of Biochemistry, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Aimée L
AL
Gommans
Department of Biochemistry, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Malcolm T
MT
Rutledge
National School of Pharmacy, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Christine T
CT
Vo
Department of Biochemistry, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Yoshio
Y
Nakatani
National School of Pharmacy, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Allan B
AB
Gamble
Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Robin A J
RA
Smith
Department of Biochemistry, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Sigurd M
SM
Wilbanks
Centre for Free Radical Research, Department of Pathology, University of Otago, PO Box 4345, Christchurch 8140, New Zealand. Electronic address: mark.hampton@otago.ac.nz.
Mark B
MB
Hampton
National School of Pharmacy, University of Otago, PO Box 56, Dunedin 9054, New Zealand. Electronic address: joel.tyndall@otago.ac.nz.
Joel D A
JD
Tyndall
D015195:Drug Design; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D017879:Isothiocyanates / Q000378:metabolism* / Q000494:pharmacology*; D019169:Jurkat Cells; D008263:Macrophage Migration-Inhibitory Factors / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D062105:Molecular Docking Simulation; D011485:Protein Binding; D011487:Protein Conformation
D004791:Enzyme Inhibitors; D017879:Isothiocyanates; D008263:Macrophage Migration-Inhibitory Factors; C037152:isothiocyanic acid; D019746:Intramolecular Oxidoreductases; C515598:MIF protein, human
Covalent; Isothiocyanate; MIF; Macrophage migration inhibitory factor; Tautomerase activity