title: Allosteric inhibition of PTP1B activity by selective modification of a non-active site cysteine residue.
abstract: The fluorogenic reagent 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABDF) attenuates the functional activity of the protein tyrosine phosphatase PTP1B by reacting selectively with a single cysteine residue, leaving other cysteines in the protein unmodified. This modification reduces Vmax without substantially affecting substrate binding (Km), indicative of an allosteric mode of inhibition. Consistent with this, the cysteine residue modified by ABDF, Cys 121, lies outside the catalytic site but makes interactions with residues that contact His 214, which has been shown to be important for catalysis. Cys 121 is highly conserved among phosphatases, and ABDF also inhibits TC-PTP and LAR. These findings illustrate that targeting cysteine residues outside catalytic sites may be exploited in allosterically regulating enzymes. Moreover, these results suggest a new strategy for inhibiting a promising diabetes target.
authors.affiliation: Sunesis Pharmaceuticals, Inc., 341 Oyster Point Boulevard, South San Francisco, California 94080, USA. hansen@sunesis.com
authors.forename: Stig K
authors.initials: SK
authors.lastname: Hansen
authors.forename: Mark T
authors.initials: MT
authors.lastname: Cancilla
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Shiau
authors.forename: Jenny
authors.initials: J
authors.lastname: Kung
authors.forename: Teresa
authors.initials: T
authors.lastname: Chen
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Erlanson
mesh_terms: D000494:Allosteric Regulation; D000495:Allosteric Site; D000818:Animals; D016466:CHO Cells; D002384:Catalysis; D006224:Cricetinae; D003545:Cysteine / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000737:chemistry; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D007328:Insulin / Q000502:physiology; D007700:Kinetics; D010069:Oxadiazoles / Q000737:chemistry; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D007328:Insulin; D010069:Oxadiazoles; C046364:4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D003545:Cysteine