Abietane-Type Diterpenoids Inhibit Protein Tyrosine Phosphatases by Stabilizing an Inactive Enzyme Conformation

Abstract

Protein tyrosine phosphatases (PTPs) contribute to a striking variety of human diseases, yet they remain vexingly difficult to inhibit with uncharged, cell-permeable molecules; no inhibitors of PTPs have been approved for clinical use. This study uses a broad set of biophysical analyses to evaluate the use of abietane-type diterpenoids, a biologically active class of phytometabolites with largely nonpolar structures, for the development of pharmaceutically relevant PTP inhibitors. Results of nuclear magnetic resonance analyses, mutational studies, and molecular dynamics simulations indicate that abietic acid can inhibit protein tyrosine phosphatase 1B, a negative regulator of insulin signaling and an elusive drug target, by binding to its active site in a non-substrate-like manner that stabilizes the catalytically essential WPD loop in an inactive conformation; detailed kinetic studies, in turn, show that minor changes in the structures of abietane-type diterpenoids (e.g., the addition of hydrogens) can improve potency (i.e., lower IC50) by 7-fold. These findings elucidate a previously uncharacterized mechanism of diterpenoid-mediated inhibition and suggest, more broadly, that abietane-type diterpenoids are a promising source of structurally diverse—and, intriguingly, microbially synthesizable—molecules on which to base the design of new PTP-inhibiting therapeutics.

Optimizing model comparison for enzymatic mechanism analysis

“…The previously published dataset for abietic acid inhibition of protein tyrosine phosphatase nonreceptor type 11 (E.C. 3.1.3.48; accession ID: Q06124) was used in this study (5). All nonlinear regression model fitting was done using the solver feature of excel (10).…”

“…This addition simplifies the creation of models of increasing complexity that can then be applied to datasets to evaluate the likelihood of potential interactions. This methodology is applied to the inhibition of protein tyrosine phosphatase nonreceptor type 11 by abietic acid (5). Protein tyrosine phosphatase nonreceptor type 11 is a member of a family of phosphatases that exhibit dynamic substrate interactions, in that they are known to rearrange when interacting with their larger peptide targets (6) and when interacting with small substrate analogues some of them are subject to substrate inhibition (7; 8).…”

Microbial Conversion of Toxic Resin Acids

“…AA and DHA extracted from food packaging paper in high concentrations can promote a tumor formation [9]. Despite their obvious toxicity on the human body, some RAs can find potential applications in drug development, since they have anti-atherosclerotic [40], anti-inflammatory [24], antidiabetic [41,42], antitumor [43], osteoprotective [44], cytotoxic [45], antimicrobial [12], and anti-biofilm [46] actions.…”

Minimally disruptive optical control of protein tyrosine phosphatase 1B

“…We examined the influence of photomodulation on enzyme kinetics by measuring the activities of PTP1BPS, PTP1BPS*, and TCPTP-LOV2 (chimera 9) on pNPP in the presence and absence of light (i.e., we used dark and light plates as described above). Briefly, we and "fminsearch" functions to fit (a) initial-rate measurements collected in the absence of inhibitors to a Michaelis−Menten model and (b) initial-rate measurements collected in the presence and absence of inhibitors to four models of inhibition (i.e., competitive, noncompetitive, uncompetitive, and mixed as described previously 59 ). (iii) We used an F-test to compare the fits of (a) a mixed model, which has two parameters, and (b) each nested singleparameter model with the lowest sum of squared errors for a given dataset.…”