The structural scaffold of the TPLATE complex deforms the membrane during plant endocytosis

Abstract

Summary paragraphEukaryotic cells maintain homeostasis of their outer membrane by controlled internalization of lipid and protein constituents via endocytosis1. Endocytosis is evolutionary conserved and utilizes similar structural folds. How these structural folds are combined into proteins and protein complexes however differs between eukaryotic kingdoms2. The TPLATE complex in plants is an evolutionary ancient protein module that combines several endocytic folds into a single octameric protein complex3-5. Its molecular architecture, lipid-nucleated condensate formation, and its requirement for clathrin cage curvature revealed its function in endocytosis initiation in plants6-8. Mechanistic understanding of how this complex drives membrane deformation during plant endocytosis is, however, lacking. Here, we used an integrative structural approach to obtain a precise molecular structure of the TPLATE complex. In addition, our approach allowed visualizing the structural flexibility that hallmarks this enigmatic complex. We prove that the intrinsic structural flexibility is required for its functionality and membrane recruitment. The membrane binding interface consists of several domains with differential lipid preferences. Finally, we show that the crescent shape of the structured part of the complex is sufficient for membrane curvature generation. Our mechanistic insight answers the long-standing question of how plants execute endocytosis without cytoskeletal-based force generation.