Structural basis for inhibition of the lysosomal two-pore channel TPC2 by a small molecule antagonist
Gamma Chi, Dawid Jaślan, Veronika Kudrina, Julia Böck, Huanyu Li, A.C.W. Pike, Susanne Rautenberg, Einar Krogsaeter, Tina Bohstedt, Dong Wang, G. McKinley, Alejandra Fernandez‐Cid, Shubhashish Mukhopadhyay, N. Burgess-Brown, Marco Keller, Franz Bracher, Christian Grimm, Katharina L. Dürr
Abstract
Two pore channels are lysosomal cation channels with crucial roles in tumor angiogenesis and viral release from endosomes. Inhibition of the two-pore channel 2 (TPC2) has emerged as potential therapeutic strategy for the treatment of cancers and viral infections, including Ebola and COVID-19. Here, we demonstrate that antagonist SG-094, a synthetic analog of the Chinese alkaloid medicine tetrandrine with increased potency and reduced toxicity, induces asymmetrical structural changes leading to a single binding pocket at only one intersubunit interface within the asymmetrical dimer. Supported by functional characterization of mutants by Ca 2+ imaging and patch clamp experiments, we identify key residues in S1 and S4 involved in compound binding to the voltage sensing domain II. SG-094 arrests IIS4 in a downward shifted state which prevents pore opening via the IIS4/S5 linker, hence resembling gating modifiers of canonical VGICs. These findings may guide the rational development of new therapeutics antagonizing TPC2 activity.