Biology subjects

Richter, J. B.

Publications and source records attributed to Richter, J. B..

2 recordsLinked to original sources

bioRxiv2019

Liquid-like protein interactions catalyze assembly of endocytic vesicles

During clathrin-mediated endocytosis, dozens of proteins assemble into an interconnected network at the plasma membrane. As early initiators of endocytosis, Eps15 and Fcho1 are responsible for locally concentrating downstream components on the membrane surface. However, they must also permit dynamic rearrangement of proteins within the budding vesicle. How do initiator proteins meet these competing demands? Here we show that Eps15 and Fcho1 rely on weak, liquid-like interactions to efficiently catalyze endocytosis. In reconstitution experiments, these weak interactions promote the assembly of protein droplets with liquid-like properties, including rapid coalescence and dynamic exchange of protein components. To probe the physiological role of liquid-like interactions among initiator proteins, we tuned the strength of initiator protein assembly in real time using light-inducible oligomerization of Eps15. Low light levels drove initiator proteins into liquid-like assemblies, restoring normal rates of endocytosis in mammalian Eps15 knockout cells. In contrast, initiator proteins formed solid-like assemblies upon exposure to higher light levels. Assembly of these structures stalled vesicle budding, likely owing to insufficient molecular rearrangement. These findings suggest that liquid-like assembly of early initiator proteins provides an optimal catalytic platform for endocytosis.

cell biology↗

bioRxiv2018

BAR scaffolds drive membrane fission by crowding disordered domains

Cylindrical protein scaffolds are thought to stabilize membrane tubules, preventing membrane fission. In contrast, Snead et al. find that when scaffold proteins assemble, bulky disordered domains within them become acutely concentrated, generating steric pressure that destabilizes tubules, driving fission.\n\nAbstractCellular membranes are continuously remodeled. The crescent-shaped bin-amphiphysinrvs (BAR) domains remodel membranes in multiple cellular pathways. Based on studies of BAR domains in isolation, the current paradigm is that they polymerize into cylindrical scaffolds that stabilize lipid tubules, preventing membrane fission. But in nature BAR domains are often part of multi-domain proteins that contain large intrinsically-disordered regions. Using in vitro and live cell assays, here we show that full-length BAR domain-containing proteins, rather than stabilizing membrane tubules, are instead surprisingly potent drivers of membrane fission. Specifically, when BAR scaffolds assemble at membrane surfaces, their bulky disordered domains become crowded, generating steric pressure that destabilizes lipid tubules. More broadly, we observe this behavior with BAR domains that have a range of curvatures. These data challenge the idea that cellular membranes adopt the curvature of BAR scaffolds, suggesting instead that the ability to concentrate disordered domains is the key requirement for membrane remodeling and fission by BAR domain-containing proteins.

biophysics↗