title: Specific inhibition of sensitized protein tyrosine phosphatase 1B (PTP1B) with a biarsenical probe.
abstract: Protein tyrosine phosphatase 1B (PTP1B) is a key regulator of the insulin-receptor and leptin-receptor signaling pathways, and it has therefore emerged as a critical antitype-II-diabetes and antiobesity drug target. Toward the goal of generating a covalent modulator of PTP1B activity that can be used for investigating its roles in cell signaling and disease progression, we report that the biarsenical probe FlAsH-EDT(2) can be used to inhibit PTP1B variants that contain cysteine point mutations in a key catalytic loop of the enzyme. The site-specific cysteine mutations have little effect on the catalytic activity of the enzyme in the absence of FlAsH-EDT(2). Upon addition of FlAsH-EDT(2), however, the activity of the engineered PTP1B is strongly inhibited, as assayed with either small-molecule or phosphorylated-peptide PTP substrates. We show that the cysteine-rich PTP1B variants can be targeted with the biarsenical probe in either whole-cell lysates or intact cells. Together, our data provide an example of a biarsenical probe controlling the activity of a protein that does not contain the canonical tetra-cysteine biarsenical-labeling sequence CCXXCC. The targeting of "incomplete" cysteine-rich motifs could provide a general means for controlling protein activity by targeting biarsenical compounds to catalytically important loops in conserved protein domains.
authors.affiliation: Amherst College, Department of Chemistry, Amherst, Massachusetts 01002, USA.
authors.forename: Oliver B
authors.initials: OB
authors.lastname: Davis
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Bishop
mesh_terms: D000595:Amino Acid Sequence; D001152:Arsenicals / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli / Q000166:cytology / Q000378:metabolism; D005453:Fluorescence; D008958:Models, Molecular; D015335:Molecular Probes / Q000737:chemistry / Q000494:pharmacology*; D015394:Molecular Structure; D009154:Mutation; D015202:Protein Engineering; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D001152:Arsenicals; D015335:Molecular Probes; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1