title: Catalytic inactivation of protein tyrosine phosphatase CD45 and protein tyrosine phosphatase 1B by polyaromatic quinones.
abstract: Polyaromatic quinones, such as the environmental pollutants 9,10-phenanthrenediones, elicit a wide range of responses including growth inhibition, immune suppression, and glucose normalization in diabetic models. Yet the molecular mechanisms behind these effects remain controversial. Here we report that many of them are oxygen-dependent and catalytic inactivators of protein tyrosine phosphatases (PTP). Under aerobic conditions, the PTP inactivation by 2-nitro-9,10-phenanthrenedione followed a pseudo-first-order process, with the rate of inactivation increasing nearly linearly with increasing inhibitor concentration, yielding apparent inactivation rate constants of 4300, 387, and 5200 M(-1) s(-1) at pH 7.2 against CD45, PTP1B, and LAR, respectively. The rate of CD45 inactivation increased approximately 25-fold from pH 6.0 to 7.5, with complete inactivation achieved using a catalytic amount (0.05 molar equiv) of the inhibitor. The quinone-catalyzed CD45 inactivation was prevented by catalase or superoxide dismutase. Inactivated CD45 after (125)I-9,10-phenanthrenedione treatment carried no radioactivity, indicating the absence of a stable inhibitor/enzyme complex. The activity of inactivated CD45 was partially restored ( approximately 10%) by hydroxylamine or dithiothreitol, supporting the presence of a small population of sulfenic acid or sulfenyl-amide species. Treatment of PTP1B with 2-nitro-9,10-phenanthrenedione resulted in the specific and sequential oxidation of the catalytic cysteine to the sulfinic and sulfonic acid. These results suggest that reactive oxygen species and the semiquinone radical, continuously generated during quinone-catalyzed redox cycling, mediate the specific catalytic cysteine oxidation. Naturally occurring quinones may act as efficient regulators of protein tyrosine phosphorylation in biological systems. Aberrant phosphotyrosine homeostasis resulting from continued polyaromatic hydrocarbon quinone exposure may play a significant role in their disease etiology.
authors.affiliation: Department of Biochemistry and Molecular Biology, Merck Frosst Centre for Therapeutic Research, Post Office Box 1005, Pointe Claire, Dorval, Quebec H9R 4P8, Canada.
authors.forename: Qingping
authors.initials: Q
authors.lastname: Wang
authors.forename: Daniel
authors.initials: D
authors.lastname: Dubé
authors.forename: Richard W
authors.initials: RW
authors.lastname: Friesen
authors.forename: Tammy G
authors.initials: TG
authors.lastname: LeRiche
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Bateman
authors.forename: Laird
authors.initials: L
authors.lastname: Trimble
authors.forename: Joe
authors.initials: J
authors.lastname: Sanghara
authors.forename: Rebecca
authors.initials: R
authors.lastname: Pollex
authors.forename: Chidambaram
authors.initials: C
authors.lastname: Ramachandran
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gresser
authors.forename: Zheng
authors.initials: Z
authors.lastname: Huang
mesh_terms: D002384:Catalysis; D003545:Cysteine / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004793:Enzyme Reactivators / Q000494:pharmacology; D006801:Humans; D019811:Hydroxylamine / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D007457:Iodine Radioisotopes / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000737:chemistry*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010616:Phenanthrenes / Q000494:pharmacology*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011809:Quinones / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013434:Sulfenic Acids / Q000378:metabolism; D013451:Sulfonic Acids / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D004793:Enzyme Reactivators; D047908:Intracellular Signaling Peptides and Proteins; D007457:Iodine Radioisotopes; D008565:Membrane Proteins; C090519:PTPRCAP protein, human; D010616:Phenanthrenes; D010750:Phosphoproteins; D011809:Quinones; D013434:Sulfenic Acids; D013451:Sulfonic Acids; D019811:Hydroxylamine; C005399:9,10-phenanthrenequinone; D017493:Leukocyte Common Antigens; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D003545:Cysteine; D010100:Oxygen; D004229:Dithiothreitol