Crystal Structures of a Rab Protein in its Inactive and Active Conformations

Stroupe, Christopher; Brunger, Axel T.

doi:10.1006/jmbi.2000.4236

Cited by 106 publications

(101 citation statements)

References 61 publications

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“…Structural analysis of Rab3a and Sec4p demonstrated that lysine residues at positions 46 and 48 reside on their surfaces accessible to effector molecules (40,43). Our mutational analysis of Rab15 reveals that lysine 48 is essential for the interaction between Rab15 and Mss4.…”

Section: Discussionmentioning

confidence: 76%

Mammalian Suppressor of Sec4 Modulates the Inhibitory Effect of Rab15 during Early Endocytosis

Strick

Francescutti

Zhao

et al. 2002

Journal of Biological Chemistry

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Rab15 is a novel endocyticEndocytosis of cell surface receptors regulates both the intensity and duration of receptor signaling by controlling the location of signaling interactions and the desensitization and recycling of activated receptors (reviewed in Refs. 1 and 2). Accordingly, endocytic compartments are highly specialized both in terms of their organization and function. The early/ sorting endosome is a major trafficking compartment from which several trafficking pathways emerge. Recently, Rab GTPases have emerged as potent regulators of membrane trafficking through early/sorting endosomes. Rabs do not regulate membrane trafficking per se but function as regulatory throttles impacting the kinetics of membrane transport steps through the recruitment of specific effectors that in turn mediate membrane transport (reviewed in Refs. 3-5). For example, Rab5 mediates the internalization and fusion of incoming endocytic vesicles in vivo (6 -8) and the homotypic fusion of endosomes in vitro (8 -12). Overexpression of the constitutively active GTP-bound mutant Rab5-Q79L in baby hamster kidney cells results in a dramatic increase in fluid phase and receptormediated endocytosis and leads to formation of enlarged early/ sorting endosomes. Conversely, overexpression of GDP-bound Rab5 (S34N) reduces endocytic uptake and results in the formation of a diffuse network of small endocytic vesicles (6 -8).Following activation on endosome membranes, Rab5-GTP drives the organization of a specialized membrane domain with distinct functional characteristics (13-15). Rab5-GTP forms this domain by recruiting the phosphatidylinositol 3-kinase hVPs34, which catalyzes the local production of PI-3-phosphate (PI3P) 1 (16 -18). Rab5-GTP and hVPs34 activities are essential for the subsequent recruitment of rabenosyn-5 and the docking protein early endosome antigen (EEA1) to early endosomal membranes through PI3P (17-22). EEA1 also interacts directly with syntaxin 13, a SNARE implicated in the fusion of early endosomes (13,23). Thus a model is emerging in which Rab5-GTP functions as a regulatory protein, driving assembly of specific effector complexes on endosomal membranes leading to membrane fusion (24). Consistent with this model, the early endocytic GTPases, Rabs 4 and 11, have also been shown to organize into distinct domains on early endosomes through the local recruitment of effectors (14, 15). Moreover, Rab4 and Rab5 function are linked through the shared effectors rabaptin-5 (25) and rabenosyn-5 (15). Thus Rab-specific domains appear to coordinate endosomal trafficking directly by communicating via shared effector complexes.The early endocytic GTPase Rab15 exhibits distinct endocytic localization and activity. Rab15 distributes between two early endosomal compartments, colocalizing with Rabs 4 and 5 on early/sorting endosomes and with Rab11 on pericentriolar recycling endosomes (26). Overexpression of activated Rab15 (Rab15-GTP) inhibits both fluid phase and receptor-mediated endocytosis in vivo and the homotypic fusion of early e...

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Section: Discussionmentioning

confidence: 76%

Mammalian Suppressor of Sec4 Modulates the Inhibitory Effect of Rab15 during Early Endocytosis

Strick

Francescutti

Zhao

et al. 2002

Journal of Biological Chemistry

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“…Recent structural studies of the GDP/GTP cycle of Rab proteins have shown that, despite their non-conventional cellular cycle, they do not depart from other small GTP-binding proteins and respond to the alternation of GDP and GTP by conformational changes and disorder-to-order transitions at the so-called switch 1 and switch 2 regions (28,29). These studies of their GDP/GTP cycles, together with the structure of the complex of Rab3 with its effector Rabphilin3 (30), the structures of Rab proteins bound to either GDP (31) or GTP analogues (32)(33)(34)(35), and genome-wide analysis of Rab sequences (5,6), suggest that the structural specificity of Rab subfamilies resides in the combination of the nucleotide-sensitive switch regions with nucleotide-insensitive regions featuring subfamily specific sequences and/or conformations.…”

mentioning

confidence: 99%

The Structural GDP/GTP Cycle of Rab11 Reveals a Novel Interface Involved in the Dynamics of Recycling Endosomes

Pasqualato

Senic-Matuglia²,

Renault³

et al. 2004

Journal of Biological Chemistry

105

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The small GTP-binding protein Rab11 is an essential regulator of the dynamics of recycling endosomes. Here we report the crystallographic analysis of the GDP/GTP cycle of human Rab11a, and a structure-based mutagenesis study that identifies a novel mutant phenotype. The crystal structures show that the nucleotide-sensitive switch 1 and 2 regions differ from those of other Rab proteins. In Rab11-GDP, they contribute to a close packed symmetrical dimer, which may associate to membranes in the cell and allow Rab11 to undergo GDP/ GTP cycles without recycling to the cytosol. The structure of active Rab11 delineates a three-dimensional site that includes switch 1 and is separate from the site defined by the Rab3/Rabphilin interface. It is proposed to form a novel interface for a Rab11 partner compatible with the simultaneous binding of another partner at the Rabphilin interface. Mutation of Ser 29 to Phe in this epitope resulted in morphological modifications of the recycling compartment that are distinct from those induced by the classical dominant-negative and constitutively active Rab11 mutants. Recycling endosomes condensed in the perinuclear region where they retained recycling transferrin, and they clustered Rab11-and EEA1-positive membranes. Altogether, our study suggests that this mutation impairs a specific subset of Rab11 interactions, possibly those involved in cytoskeleton-based movements driving the slow recycling pathway.

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“…Like Ras, Rab proteins contain an effector domain that undergoes major conformational changes during GTP hydrolysis (44,53). Cycling between the GTP and GDP form requires additional proteins including GTPase-activating proteins and guanine nucleotide exchange factors (for recent reviews see references 46, 52, and 57).…”

mentioning

confidence: 99%

Rab3D Is Not Required for Exocrine Exocytosis but for Maintenance of Normally Sized Secretory Granules

Riedel

Antonin

Fernández‐Chacón

et al. 2002

Molecular and Cellular Biology

125

106

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Rab3D, a member of the Rab3 subfamily of the Rab/ypt GTPases, is expressed on zymogen granules in the pancreas as well as on secretory vesicles in mast cells and in the parotid gland. To shed light on the function of Rab3D, we have generated Rab3D-deficient mice. These mice are viable and have no obvious phenotypic changes. Secretion of mast cells is normal as revealed by capacitance patch clamping. Furthermore, enzyme content and overall morphology are unchanged in pancreatic and parotid acinar cells of knockout mice. Both the exocrine pancreas and the parotid gland show normal release kinetics in response to secretagogue stimulation, suggesting that Rab3D is not involved in exocytosis. However, the size of secretory granules in both the exocrine pancreas and the parotid gland is significantly increased, with the volume being doubled. We conclude that Rab3D exerts its function during granule maturation, possibly by preventing homotypic fusion of secretory granules.

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Crystal Structures of a Rab Protein in its Inactive and Active Conformations

Cited by 106 publications

References 61 publications

Mammalian Suppressor of Sec4 Modulates the Inhibitory Effect of Rab15 during Early Endocytosis

Mammalian Suppressor of Sec4 Modulates the Inhibitory Effect of Rab15 during Early Endocytosis

The Structural GDP/GTP Cycle of Rab11 Reveals a Novel Interface Involved in the Dynamics of Recycling Endosomes

Rab3D Is Not Required for Exocrine Exocytosis but for Maintenance of Normally Sized Secretory Granules

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