A composition-dependent molecular clutch between T cell signaling condensates and actin

• DOI: 10.7554/elife.42695
• Publication Date: 2019-07-03T12:00:15Z
• Authors: Jonathon A Ditlev; Anthony R Vega; Darius Vasco Köster; Xiaolei Su; Tomomi Tani; Ashley M Lakoduk; Ronald D Vale; Satyajit Mayor; Khuloud Jaqaman; Michael K Rosen
• Keywords: 0301 basic medicine; 570; Biomedical and clinical sciences; actin cytoskeleton; QH301-705.5; Science; T-Lymphocytes; chemical biology; Lymphocyte Activation; LAT microclusters; 03 medical and health sciences; Biochemistry and Chemical Biology; cell biology; biochemistry; Humans; human; Biology (General); Adaptor Proteins, Signal Transducing; Oncogene Proteins; Q; Signal Transducing; R; Adaptor Proteins; Health sciences; Membrane Proteins; Biological Sciences; QP; Actins; QR; Biological sciences; Protein Transport; compositional control; Medicine; biomolecular condensate; Biochemistry and Cell Biology; T cell signaling; Protein Multimerization; biochemical reconstitution; Wiskott-Aldrich Syndrome Protein; Protein Binding; Signal Transduction

During T cell activation, biomolecular condensates form at the immunological synapse (IS) through multivalency-driven phase separation of LAT, Grb2, Sos1, SLP-76, Nck, and WASP. These condensates move radially at the IS, traversing successive radially-oriented and concentric actin networks. To understand this movement, we biochemically reconstituted LAT condensates with actomyosin filaments. We found that basic regions of Nck and N-WASP/WASP promote association and co-movement of LAT condensates with actin, indicating conversion of weak individual affinities to high collective affinity upon phase separation. Condensates lacking these components were propelled differently, without strong actin adhesion. In cells, LAT condensates lost Nck as radial actin transitioned to the concentric network, and engineered condensates constitutively binding actin moved aberrantly. Our data show that Nck and WASP form a clutch between LAT condensates and actin in vitro and suggest that compositional changes may enable condensate movement by distinct actin networks in different regions of the IS.