Identifying Potential Dsl1 Vesicle Tethering Interactions Using Proximity Labeling

Abstract

Multi-subunit tethering complexes (MTCs) help vesicles dock with and fuse to target membranes in eukaryotic cells. The simplest member of the largest class of MTCs is Dsl1, which facilitates vesicle tethering and fusion in the Golgi-ER retrograde protein trafficking pathway. Previous work has revealed one method Dsl1 uses to capture vesicles traversing this pathway: an unstructured region of Dsl1 known as the “lasso” binds to the vesicle coat protein COPI. However, additional research has suggested that another Dsl1 domain—the highly conserved “E domain”— enables vesicle tethering even when the lasso is absent. The mechanism by which the E domain tethers vesicles remains unknown. We used proximity labeling to identify proteins that interact with the Dsl1 E domain and lasso in vivo. Our findings suggest that COPI coat proteins, regulators of COPI uncoating, and regulators of the actin cytoskeleton may play a role in Dsl1 vesicle tethering. These results provide insight into how MTCs latch on to specific transport vesicles, a process that promotes efficient intracellular trafficking.