Title
The KIM-family Protein Tyrosine Phosphatases use distinct reversible oxidation intermediates: intramolecular or intermolecular disulfide bond formation
Author
Luciana E. S. F. Machado, Tun-Li Shen, Rebecca Page, Wolfgang Peti
Year
2017
Journal
The Journal of Biological Chemistry
Abstract
The kinase interaction motif (KIM) family of protein tyrosine phosphatases (PTPs) includes hematopoietic protein tyrosine phosphatase (HePTP), striatal-enriched protein tyrosine phosphatase (STEP), and protein tyrosine phosphatase receptor type R (PTPRR). KIM-PTPs bind and dephosphorylate mitogen activated protein kinases (MAPKs) and thereby critically modulate cell proliferation and differentiation. PTP activity can readily be diminished by reactive oxygen species (ROS), e.g. H2O2, that oxidize the catalytically indispensable active-site cysteine. This initial oxidation generates an unstable sulfenic acid intermediate that is quickly converted into either a sulfinic/sulfonic acid (catalytically dead and irreversible inactivation) or a stable sulfenamide or disulfide bond intermediate (reversible inactivation). Critically, our understanding of ROS-mediated PTP oxidation is not yet sufficient to predict PTPs molecular responses to oxidative stress. However, identifying distinct responses will enable novel routes for PTP-selective drug design, important for managing diseases such as cancer and Alzheimer's disease. Therefore, we performed a detailed biochemical and molecular study of all KIM-PTP family members to determine their H2O2 oxidation profiles and identify their reversible inactivation mechanism(s). We show that despite having nearly identical 3D structures and sequences, each KIM-PTP family member has a unique oxidation profile. Furthermore, we also show that while STEP and PTPRR stabilize their reversibly oxidized state by forming an intramolecular disulfide bond, HePTP uses an unexpected mechanism, namely, formation of a reversible intermolecular disulfide bond. In summary, despite being closely related KIM-PTPs significantly differ in oxidation profiles. These findings highlight that oxidation protection is critical when analyzing PTPs, for example, in drug screening.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Thermal stability, Thermodynamics, Biochemistry