TDP-43 -helical structure tunes liquid-liquid phase separation and function

AbstractLiquid-liquid phase separation (LLPS) is involved in the formation of membraneless organelles (MLOs) associated with RNA processing. Present in several MLOs, TDP-43 undergoes LLPS and is linked to the pathogenesis of amyotrophic lateral sclerosis (ALS). While some disease variants of TDP-43 disrupt self-interaction and function, here we show that designed single mutations can enhance TDP-43 assembly and function via modulating helical structure. Using molecular simulation and NMR spectroscopy, we observe large structural changes in a dimeric TDP-43. Two conserved glycine residues (G335 and G338) are potent inhibitors of helical extension and helix-helix interaction, which are removed in part by variants including the ALS-associated G335D. Substitution to helix-enhancing alanine at either of these positions dramatically enhances phase separation in vitro and decreases fluidity of phase separated TDP-43 reporter compartments in cells. Furthermore, G335A increases TDP-43 splicing function in a mini-gene assay. Therefore, TDP-43 helical region serves as a short but uniquely tunable module that shows promise as for controlling assembly and function in cellular and synthetic biology applications of LLPS.

Conicella, A. E., Dignon, G. L., Zerze, G. H., Schmidt, H. B., DOrdine, A. M., Kim, Y. C., ... Fawzi, N. L.

Conicella, Alexander E||Dignon, Gregory L||Zerze, Gül H||Schmidt, Hermann Broder||D’Ordine, Alexandra M||Kim, Young C||Rohatgi, Rajat||Ayala, Yuna M||Mittal, Jeetain||Fawzi, Nicolas L

TDP-43 -helical structure tunes liquid-liquid phase separation and function Institutional Repository Document