The Structural Basis for Activation of the Rab Ypt1p by the TRAPP Membrane-Tethering Complexes

Cai, Yiying; Chin, Harvey F.; Lazarova, Darina L.; Menon, Shekar; Fu, Chao; Cai, Huaqing; Sclafani, Anthony M.; Rodgers, David W.; Cruz, Enrique M. De La; Ferro‐Novick, Susan; Reinisch, Karin M

doi:10.1016/j.cell.2008.04.049

Cited by 176 publications

(373 citation statements)

References 46 publications

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“…Our findings suggest that the HVDs of individual Rab proteins play distinct roles in membrane targeting. In the case of Rab1 and Rab5, the HVD is not required for membrane targeting, probably because it is not involved in binding with potential targeting factors, including effectors and GEFs (12,(31)(32)(33). It serves rather as an anchoring chain that physically connects the functional GTPase domain with the membrane.…”

Section: Discussionmentioning

confidence: 99%

The role of the hypervariable C-terminal domain in Rab GTPases membrane targeting

Zhao

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Intracellular membrane trafficking requires correct and specific localization of Rab GTPases. The hypervariable C-terminal domain (HVD) of Rabs is posttranslationally modified by isoprenyl moieties that enable membrane association. A model asserting HVDdirected targeting has been contested in previous studies, but the role of the Rab HVD and the mechanism of Rab membrane targeting remain elusive. To elucidate the function of the HVD, we have substituted this region with an unnatural polyethylenglycol (PEG) linker by using oxime ligation. The PEGylated Rab proteins undergo normal prenylation, underlining the unique ability of the Rab prenylation machinery to process the Rab family with diverse C-terminal sequences. Through localization studies and functional analyses of semisynthetic PEGylated Rab1, Rab5, Rab7, and Rab35 proteins, we demonstrate that the role of the HVD of Rabs in membrane targeting is more complex than previously understood. The HVD of Rab1 and Rab5 is dispensable for membrane targeting and appears to function simply as a linker between the GTPase domain and the membrane. The N-terminal residues of the Rab7 HVD are important for late endosomal/lysosomal localization, apparently due to their involvement in interaction with the Rab7 effector Rabinteracting lysosomal protein. The C-terminal polybasic cluster of the Rab35 HVD is essential for plasma membrane (PM) targeting, presumably because of the electrostatic interaction with negatively charged lipids on the PM. Our findings suggest that Rab membrane targeting is dictated by a complex mechanism involving GEFs, GAPs, effectors, and C-terminal interaction with membranes to varying extents, and possibly other binding partners. Interacting with a complex network of Rab regulators and effectors, Rab GTPases regulate these processes through a spatiotemporally controlled GTPase cycle and their distribution in cells. The GTPase cycle is strictly regulated by guanine nucleotide exchange factors (GEFs) that mediate GDP/GTP exchange and by GTPase-activating proteins (GAPs) that accelerate the hydrolysis of GTP. Active (GTP-bound) Rab proteins associate with distinct intracellular compartments and direct vesicular transport by recruiting a multitude of Rab-specific effectors, including tethering complexes and motor proteins.Rab proteins are posttranslationally modified at the C terminus with prenyl groups that function as membrane anchors. Rab prenylation involves covalent attachment of the geranylgeranyl (C-20 isoprenyl) moiety to one or two C-terminal cysteine residues of the protein substrate via a stable thioether linkage (4). Unlike other protein prenyltransferases that recognize the Cterminal CaaX motif of protein substrates (e.g., Ras and Rho), Rab geranylgeranyl transferase (RabGGTase) does not recognize its protein substrates (Rab proteins) directly but requires the adaptor Rab escort protein (REP). Rab prenylation requires the formation of a ternary catalytic Rab:REP:RabGGTase complex (5-7). It remains elusive how the single Rab prenylation machin...

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Section: Discussionmentioning

confidence: 99%

The role of the hypervariable C-terminal domain in Rab GTPases membrane targeting

Zhao

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Moreover, TRAPPI functions as a GEF for Ypt1 in a manner that is thought to generate activated Ypt1 on the surface of Golgi acceptor membranes and/or COPII vesicles (Jones et al 2000;Wang et al 2000;Lord et al 2011). A subassembly of TRAPPI consisting of Bet3, Bet5, Trs23, and Trs31 binds Ypt1p and catalyzes nucleotide exchange by stabilizing an open form of this GTPase (Cai et al 2008). TRAPPI does not appear to interact directly with Uso1, although Ypt1 activation could serve to coordinate the long-distance tethering mediated by Uso1 with a closer TRAPPI-dependent tethering event.…”

Section: Vesicle Tetheringmentioning

confidence: 99%

Secretory Protein Biogenesis and Traffic in the Early Secretory Pathway

2013

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The secretory pathway is responsible for the synthesis, folding, and delivery of a diverse array of cellular proteins. Secretory protein synthesis begins in the endoplasmic reticulum (ER), which is charged with the tasks of correctly integrating nascent proteins and ensuring correct post-translational modification and folding. Once ready for forward traffic, proteins are captured into ER-derived transport vesicles that form through the action of the COPII coat. COPII-coated vesicles are delivered to the early Golgi via distinct tethering and fusion machineries. Escaped ER residents and other cycling transport machinery components are returned to the ER via COPI-coated vesicles, which undergo similar tethering and fusion reactions. Ultimately, organelle structure, function, and cell homeostasis are maintained by modulating protein and lipid flux through the early secretory pathway. In the last decade, structural and mechanistic studies have added greatly to the strong foundation of yeast genetics on which this field was built. Here we discuss the key players that mediate secretory protein biogenesis and trafficking, highlighting recent advances that have deepened our understanding of the complexity of this conserved and essential process. TABLE OF CONTENTS Abstract 383Introduction 384

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“…17,19,20 Arabidopsis RAB-D2a, a homolog of yeast Ypt1 and animal Rab1, has been localized to a population of TGN. 31 So we tested if expression of either wild type or constitutively active RAB-D2a(Q67L) could rescue the growth of attrs130.…”

confidence: 99%

“…15 Here, we extend our functional analysis of TRAPPII and report that, TRAPPII in Arabidopsis is required for polar distribution of AUX1, an auxin influx carrier in protophloem cells and epidermal cells in Arabidopsis root tips. In yeast cells, TRAPPII has been implicated to serve as a GEF for the activation of both Ypt1 and Ypt31/32, [16][17][18][19] while in mammalian cells, TRAPPII acts as a GEF for Rab1 (homolog of yeast Ypt1). 20 We show here that TRAPPII in Arabidopsis is not functionally linked the Rab-D2a protein, a homolog of yeast Ypt1 and animal Rab1 proteins.…”

mentioning

confidence: 99%

Arabidopsis TRAPPII is functionally linked to Rab-A, but not Rab-D in polar protein trafficking intrans-Golgi network

Zheng

2011

Plant Signaling & Behavior

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The Structural Basis for Activation of the Rab Ypt1p by the TRAPP Membrane-Tethering Complexes

Cited by 176 publications

References 46 publications

The role of the hypervariable C-terminal domain in Rab GTPases membrane targeting

The role of the hypervariable C-terminal domain in Rab GTPases membrane targeting

Secretory Protein Biogenesis and Traffic in the Early Secretory Pathway

Arabidopsis TRAPPII is functionally linked to Rab-A, but not Rab-D in polar protein trafficking intrans-Golgi network

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