DESCRIPTION With BI-0314 we report the discovery of the first small molecule allosteric modulator for STEP (STriatal-Enriched protein tyrosine Phosphatase), that binds to the phosphatase domain and upregulates the catalytic activity of STEP. Its activity has been demonstrated in enzymatic assays showing an activation by ~30% at 100µM and ~60% at 500µM in complementary readouts and on different STEP constructs. The selectivity against PTP1B and TCPTP has been tested and no activation at 500µM could be seen. To elucidate the mode of action, an X-ray structure with BI-0314 bound STEP has been solved demonstrating remote site binding ~20 Å away from the active phosphatase site. The allosteric binding site could be confirmed also in solution by N TROSY NMR. Long range allosteric mechanisms have been confirmed by extensive molecular dynamics simulations. The identification of a druggable allosteric pocket provides new opportunities for the discovery of selective STEP modulators as treatment options for CNS disorders.

DESCRIPTION With BI-0314 we report the discovery of the first small molecule allosteric modulator for STEP (STriatal-Enriched Protein Tyrosine Phosphatase), that binds to the phosphatase domain and upregulates the catalytic activity of STEP. Its activity has been demonstrated in enzymatic assays showing an activation by ~30% at 100 µM and ~60% at 500 µM in complementary readouts and on different STEP constructs. The selectivity against PTP1B and TCPTP has been tested and no activation at 500 µM could be seen. To elucidate the mode of action, an X-ray structure with BI-0314 bound STEP has been solved demonstrating remote site binding ~20 Å away from the active phosphatase site. The allosteric binding site could be confirmed also in solution by 15N TROSY NMR. Long range allosteric mechanisms have been confirmed by extensive molecular dynamics simulations. The identification of a druggable allosteric pocket provides new opportunities for the discovery of selective STEP modulators as treatment options for CNS disorders. (opnMe Portal)