7kmt
Structure of the yeast TRAPPIII-Ypt1(Rab1) complex
Structural highlights
FunctionBET3_YEAST Component of the TRAPP I, TRAPP II and TRAPP III complexes which act as guanine nucleotide exchange factors (GEF) for YPT1. TRAPP I plays a key role in the late stages of endoplasmic reticulum to Golgi traffic. TRAPP II plays a role in intra-Golgi transport. TRAPP III plays a role in autophagosome formation. Required for sporulation. Has a role late in meiosis following DNA replication.[1] [2] [3] [4] [5] Publication Abstract from PubMedThe GTPase Rab1 is a master regulator of the early secretory pathway and is critical for autophagy. Rab1 activation is controlled by its guanine nucleotide exchange factor, the multisubunit TRAPPIII complex. Here, we report the 3.7 A cryo-EM structure of the Saccharomyces cerevisiae TRAPPIII complex bound to its substrate Rab1/Ypt1. The structure reveals the binding site for the Rab1/Ypt1 hypervariable domain, leading to a model for how the complex interacts with membranes during the activation reaction. We determined that stable membrane binding by the TRAPPIII complex is required for robust activation of Rab1/Ypt1 in vitro and in vivo, and is mediated by a conserved amphipathic alpha-helix within the regulatory Trs85 subunit. Our results show that the Trs85 subunit serves as a membrane anchor, via its amphipathic helix, for the entire TRAPPIII complex. These findings provide a structural understanding of Rab activation on organelle and vesicle membranes. Structural basis of TRAPPIII-mediated Rab1 activation.,Joiner AM, Phillips BP, Yugandhar K, Sanford EJ, Smolka MB, Yu H, Miller EA, Fromme JC EMBO J. 2021 Jun 15;40(12):e107607. doi: 10.15252/embj.2020107607. Epub 2021 May , 21. PMID:34018207[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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