Abstract
Members of the Tre2-Bub2-Cdc16 (TBC) family often function to regulate membrane trafficking and to control signaling transductions pathways. As a member of the TBC family, TBC1D23 is critical for endosome-to-Golgi cargo trafficking by serving as a bridge between Golgi-bound golgin-97/245 and the WASH/FAM21 complex on endosomal vesicles. However, the exact mechanisms by which TBC1D23 regulates cargo transport are poorly understood. Here, we present the crystal structure of the N-terminus of TBC1D23 (D23N), which consists of both the TBC and rhodanese domains. We show that the rhodanese domain is unlikely to be an active sulfurtransferase or phosphatase, despite containing a putative catalytic site. Instead, it packs against the TBC domain and forms part of the platform to interact with golgin-97/245. Using the zebrafish model, we show that impacting golgin-97/245-binding, but not the putative catalytic site, impairs neuronal growth and brain development. Altogether, our studies provide structural and functional insights into an essential protein that is required for organelle-specific trafficking and brain development.
Highlights
IntroductionMembrane vesicle trafficking involves movement of molecules (cargoes) between membrane organelles, in the form of membrane-bound microsized vesicles [1,2]
In eukaryotic cells, membrane vesicle trafficking involves movement of molecules between membrane organelles, in the form of membrane-bound microsized vesicles [1,2].Vesicle trafficking is fundamental to many cellular and physiological processes, including signaling transduction, metabolic homeostasis, synaptic neurotransmission, endocrine secretion, et al [1,3]
The crystal structure of diffraction-quality crystals of the TBC1D23 N-terminal region (D23N) was determined by selenium single-wavelength anomalous diffraction (Se-SAD) and refined to a resolution of 2.5 Å (S1 Table)
Summary
Membrane vesicle trafficking involves movement of molecules (cargoes) between membrane organelles, in the form of membrane-bound microsized vesicles [1,2]. Vesicle trafficking is fundamental to many cellular and physiological processes, including signaling transduction, metabolic homeostasis, synaptic neurotransmission, endocrine secretion, et al [1,3]. Dysfunctions in vesicle trafficking contribute to certain types of cancer, immunological disorders, diabetes, and most importantly, many kinds of neurological disorders [4,5]. The Rab family of small GTPases play a central role in vesicular trafficking and regulate many steps, including vesicle formation, vesicle movement, and membrane fusion [6,7,8]. Members of the Tre2-Bub2-Cdc (TBC) family often participate in membrane trafficking by functioning as Rab GTPase-activating proteins (GAPs) [9,10].
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