101
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Shah AH, Cianciola NL, Mills JL, Sönnichsen FD, Carlin C. Adenovirus RIDalpha regulates endosome maturation by mimicking GTP-Rab7. ACTA ACUST UNITED AC 2007; 179:965-80. [PMID: 18039930 PMCID: PMC2099200 DOI: 10.1083/jcb.200702187] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The small guanosine triphosphatase Rab7 regulates late endocytic trafficking. Rab7-interacting lysosomal protein (RILP) and oxysterol-binding protein-related protein 1L (ORP1L) are guanosine triphosphate (GTP)-Rab7 effectors that instigate minus end-directed microtubule transport. We demonstrate that RILP and ORP1L both interact with the group C adenovirus protein known as receptor internalization and degradation alpha (RIDalpha), which was previously shown to clear the cell surface of several membrane proteins, including the epidermal growth factor receptor and Fas (Carlin, C.R., A.E. Tollefson, H.A. Brady, B.L. Hoffman, and W.S. Wold. 1989. Cell. 57:135-144; Shisler, J., C. Yang, B. Walter, C.F. Ware, and L.R. Gooding. 1997. J. Virol. 71:8299-8306). RIDalpha localizes to endocytic vesicles but is not homologous to Rab7 and is not catalytically active. We show that RIDalpha compensates for reduced Rab7 or dominant-negative (DN) Rab7(T22N) expression. In vitro, Cu(2+) binding to RIDalpha residues His75 and His76 facilitates the RILP interaction. Site-directed mutagenesis of these His residues results in the loss of RIDalpha-RILP interaction and RIDalpha activity in cells. Additionally, expression of the RILP DN C-terminal region hinders RIDalpha activity during an acute adenovirus infection. We conclude that RIDalpha coordinates recruitment of these GTP-Rab7 effectors to compartments that would ordinarily be perceived as early endosomes, thereby promoting the degradation of selected cargo.
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Affiliation(s)
- Ankur H Shah
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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102
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Zhu G, Chen J, Liu J, Brunzelle JS, Huang B, Wakeham N, Terzyan S, Li X, Rao Z, Li G, Zhang XC. Structure of the APPL1 BAR-PH domain and characterization of its interaction with Rab5. EMBO J 2007; 26:3484-93. [PMID: 17581628 PMCID: PMC1933402 DOI: 10.1038/sj.emboj.7601771] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 05/30/2007] [Indexed: 12/31/2022] Open
Abstract
APPL1 is an effector of the small GTPase Rab5. Together, they mediate a signal transduction pathway initiated by ligand binding to cell surface receptors. Interaction with Rab5 is confined to the amino (N)-terminal region of APPL1. We report the crystal structures of human APPL1 N-terminal BAR-PH domain motif. The BAR and PH domains, together with a novel linker helix, form an integrated, crescent-shaped, symmetrical dimer. This BAR–PH interaction is likely conserved in the class of BAR-PH containing proteins. Biochemical analyses indicate two independent Rab-binding sites located at the opposite ends of the dimer, where the PH domain directly interacts with Rab5 and Rab21. Besides structurally supporting the PH domain, the BAR domain also contributes to Rab binding through a small surface region in the vicinity of the PH domain. In stark contrast to the helix-dominated, Rab-binding domains previously reported, APPL1 PH domain employs β-strands to interact with Rab5. On the Rab5 side, both switch regions are involved in the interaction. Thus we identified a new binding mode between PH domains and small GTPases.
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Affiliation(s)
- Guangyu Zhu
- Crystallography Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Jia Chen
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jay Liu
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Joseph S Brunzelle
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg Medical School, Northwestern University, Chicago, IL, USA
| | - Bo Huang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Nancy Wakeham
- Crystallography Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Simon Terzyan
- Crystallography Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Xuemei Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Zihe Rao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Guangpu Li
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Xuejun C Zhang
- Crystallography Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Crystallography Research Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. Tel.: +1 405 271 7402; Fax: +1 405 271 7953; E-mail:
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103
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Shintani M, Tada M, Kobayashi T, Kajiho H, Kontani K, Katada T. Characterization of Rab45/RASEF containing EF-hand domain and a coiled-coil motif as a self-associating GTPase. Biochem Biophys Res Commun 2007; 357:661-7. [PMID: 17448446 DOI: 10.1016/j.bbrc.2007.03.206] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 03/30/2007] [Indexed: 11/15/2022]
Abstract
Rab-family GTPases function as key regulators for membrane traffic. Among them, Rab45/RASEF is an atypical GTPase in that it contains a coiled-coil motif at the mid region and a distinct N-terminal EF-hand domain with C-terminal Rab-homology domain. Here, we provide the initial biochemical characterization and intracellular localization of human Rab45. Rab45 bound guanine nucleotide tri- and di-phosphates through the C-terminal Rab domain. Rab45 was capable of self-interacting, and the self-interaction required the mid region containing the coiled-coil motif. Rab45 expressed in HeLa cells was localized in a small patch in the perinuclear area of the cell, and the localization was regulated by the guanine nucleotide-bound states of Rab45. Interestingly, the mid region, together with Rab domain, appeared to be essential for the characteristic perinuclear localization of Rab45, indicating that the self-interaction may be involved in the intracellular localization of Rab45.
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Affiliation(s)
- Mami Shintani
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
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104
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Johansson M, Rocha N, Zwart W, Jordens I, Janssen L, Kuijl C, Olkkonen VM, Neefjes J. Activation of endosomal dynein motors by stepwise assembly of Rab7-RILP-p150Glued, ORP1L, and the receptor betalll spectrin. ACTA ACUST UNITED AC 2007; 176:459-71. [PMID: 17283181 PMCID: PMC2063981 DOI: 10.1083/jcb.200606077] [Citation(s) in RCA: 358] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The small GTPase Rab7 controls late endocytic transport by the minus end–directed motor protein complex dynein–dynactin, but how it does this is unclear. Rab7-interacting lysosomal protein (RILP) and oxysterol-binding protein–related protein 1L (ORP1L) are two effectors of Rab7. We show that GTP-bound Rab7 simultaneously binds RILP and ORP1L to form a RILP–Rab7–ORP1L complex. RILP interacts directly with the C-terminal 25-kD region of the dynactin projecting arm p150Glued, which is required for dynein motor recruitment to late endocytic compartments (LEs). Still, p150Glued recruitment by Rab7–RILP does not suffice to induce dynein-driven minus-end transport of LEs. ORP1L, as well as βIII spectrin, which is the general receptor for dynactin on vesicles, are essential for dynein motor activity. Our results illustrate that the assembly of microtubule motors on endosomes involves a cascade of linked events. First, Rab7 recruits two effectors, RILP and ORP1L, to form a tripartite complex. Next, RILP directly binds to the p150Glued dynactin subunit to recruit the dynein motor. Finally, the specific dynein motor receptor Rab7–RILP is transferred by ORP1L to βIII spectrin. Dynein will initiate translocation of late endosomes to microtubule minus ends only after interacting with βIII spectrin, which requires the activities of Rab7–RILP and ORP1L.
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Affiliation(s)
- Marie Johansson
- Department of Molecular Medicine, National Public Health Institute, Biomedicum, FI-00251 Helsinki, Finland
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105
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Lévesque K, Halvorsen M, Abrahamyan L, Chatel-Chaix L, Poupon V, Gordon H, DesGroseillers L, Gatignol A, Mouland AJ. Trafficking of HIV-1 RNA is mediated by heterogeneous nuclear ribonucleoprotein A2 expression and impacts on viral assembly. Traffic 2007; 7:1177-93. [PMID: 17004321 DOI: 10.1111/j.1600-0854.2006.00461.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Few details are known about how the human immunodeficiency virus type 1 (HIV-1) genomic RNA is trafficked in the cytoplasm. Part of this process is controlled by the activity of heterogeneous nuclear ribonucleoprotein A2 (hnRNP A2). The role of hnRNP A2 during the expression of a bona fide provirus in HeLa cells is investigated in this study. Using immunofluorescence and fluorescence in situ hybridization techniques, we show that knockdown of hnRNP A2 expression in HIV-1-expressing cells results in the rapid accumulation of HIV-1 genomic RNA in a distinct, cytoplasmic space that corresponds to the microtubule-organizing center (MTOC). The RNA exits in the nucleus and accumulates at the MTOC region as a result of hnRNP A2 knockdown even during the expression of a provirus harboring mutations in the hnRNP A2-response element (A2RE), the expression of which results in nuclear retention of genomic RNA. We also demonstrate that hnRNP A2 expression is required for downstream trafficking of genomic RNA from the MTOC in the cytoplasm. Genomic RNA localization at the MTOC that was both the result of hnRNP A2 knockdown and the overexpression of Rab7-interacting lysosomal protein had little effect on pr55Gag synthesis but negatively influenced virus production and infectivity. These data indicate that altered HIV-1 genomic RNA localization modulates viral assembly and that the MTOC serves as a central site to which HIV-1 genomic RNA converges following its exit from the nucleus, with the host protein, hnRNP A2, playing a central role in taking it to and from this site in the cell.
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Affiliation(s)
- Kathy Lévesque
- HIV-1 RNA Trafficking Laboratory, 3755 Côte-Ste-Catherine Road, Montréal, Québec, Canada H3T 1E2
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106
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Jagoe WN, Lindsay AJ, Read RJ, McCoy AJ, McCaffrey MW, Khan AR. Crystal structure of rab11 in complex with rab11 family interacting protein 2. Structure 2006; 14:1273-83. [PMID: 16905101 DOI: 10.1016/j.str.2006.06.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 05/08/2006] [Accepted: 06/09/2006] [Indexed: 12/27/2022]
Abstract
The small GTPase Rab11 regulates the recycling of endosomes to the plasma membrane via interactions with the Rab11 family of interacting proteins (FIPs). FIPs contain a highly conserved Rab binding domain (RBD) at their C termini whose structure is unknown. Here, we have determined the crystal structure of the RBD of FIP2 in complex with Rab11(GTP) by single wavelength anomalous diffraction methods. The overall structure is a heterotetramer with dyad symmetry, arranged as a Rab11-(FIP2)2-Rab11 complex. FIP2 forms a central alpha-helical coiled coil, with both helices contributing to the Rab11 binding patch on equivalent and opposite sides of the homodimer. Switch 1 of Rab11 is embedded between the two helices, while switch 2 remains flexible and is peripherally associated with the effector. The complex reveals the structural basis for Rab11 recognition by FIPs and suggests the molecular mechanisms underlying endocytic recycling pathways.
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Affiliation(s)
- William N Jagoe
- School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland
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107
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Shiba T, Koga H, Shin HW, Kawasaki M, Kato R, Nakayama K, Wakatsuki S. Structural basis for Rab11-dependent membrane recruitment of a family of Rab11-interacting protein 3 (FIP3)/Arfophilin-1. Proc Natl Acad Sci U S A 2006; 103:15416-21. [PMID: 17030804 PMCID: PMC1622838 DOI: 10.1073/pnas.0605357103] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Family of Rab11-interacting protein (FIP)3/Arfophlin-1 and FIP4/Arfophilin-2 are dual effectors for Rab11 and ADP ribosylation factor (ARF)5/ARF6, which are involved in membrane delivery from recycling endosomes to the plasma membrane during cytokinesis. Here, we define the distinct C-terminal binding regions of FIP3 and FIP4 for Rab11 and ARF5/ARF6. Furthermore, we determined the crystal structure of Rab11 in complex with the Rab11-binding domain (RBD) of FIP3. The long amphiphilic alpha-helix of FIP3-RBD forms a parallel coiled-coil homodimer, with two symmetric interfaces with two Rab11 molecules. The hydrophobic side of the RBD helix is involved in homodimerization and mediates the interaction with the Rab11 switch 1 region, whereas the opposite hydrophilic side interacts with the Rab11 switch 2 and is the major factor contributing to the binding specificity. The bivalent interaction of FIP3 with Rab11 at the C terminus allows FIP3 to coordinately function with other binding partners, including ARFs.
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Affiliation(s)
- Tomoo Shiba
- *Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan; and
| | - Hiroshi Koga
- Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masato Kawasaki
- *Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan; and
| | - Ryuichi Kato
- *Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan; and
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Soichi Wakatsuki
- *Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan; and
- To whom correspondence should be addressed. E-mail:
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108
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Terebiznik MR, Vazquez CL, Torbicki K, Banks D, Wang T, Hong W, Blanke SR, Colombo MI, Jones NL. Helicobacter pylori VacA toxin promotes bacterial intracellular survival in gastric epithelial cells. Infect Immun 2006; 74:6599-614. [PMID: 17000720 PMCID: PMC1698066 DOI: 10.1128/iai.01085-06] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Helicobacter pylori colonizes the gastric epithelium of at least 50% of the world's human population, playing a causative role in the development of chronic gastritis, peptic ulcers, and gastric adenocarcinoma. Current evidence indicates that H. pylori can invade epithelial cells in the gastric mucosa. However, relatively little is known about the biology of H. pylori invasion and survival in host cells. Here, we analyze both the nature of and the mechanisms responsible for the formation of H. pylori's intracellular niche. We show that in AGS cells infected with H. pylori, bacterium-containing vacuoles originate through the fusion of late endocytic organelles. This process is mediated by the VacA-dependent retention of the small GTPase Rab7. In addition, functional interactions between Rab7 and its downstream effector, Rab-interacting lysosomal protein (RILP), are necessary for the formation of the bacterial compartment since expression of mutant forms of RILP or Rab7 that fail to bind each other impaired the formation of this unique bacterial niche. Moreover, the VacA-mediated sequestration of active Rab7 disrupts the full maturation of vacuoles as assessed by the lack of both colocalization with cathepsin D and degradation of internalized cargo in the H. pylori-containing vacuole. Based on these findings, we propose that the VacA-dependent isolation of the H. pylori-containing vacuole from bactericidal components of the lysosomal pathway promotes bacterial survival and contributes to the persistence of infection.
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Affiliation(s)
- M R Terebiznik
- Hospital for Sick Children, 555 University Avenue, Toronto, Canada M5G 1X9
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109
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Wang T, Hong W. RILP interacts with VPS22 and VPS36 of ESCRT-II and regulates their membrane recruitment. Biochem Biophys Res Commun 2006; 350:413-23. [PMID: 17010938 DOI: 10.1016/j.bbrc.2006.09.064] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Accepted: 09/14/2006] [Indexed: 11/17/2022]
Abstract
RILP is emerging as a key regulator of late endocytic pathway by functioning as a downstream effector of activated Rab7 and Rab34, while ESCRT-I-->ESCRT-II-->ESCRT-III machinery acts in sorting proteins to the multivesicular body (MVB) initiated at the early/sorting endosome. We show here that the early machinery is integrated with the late machinery through a novel regulatory loop in which RILP interacts with VPS22 and VPS36 of ESCRT-II to mediate their membrane recruitment. The N-terminal and C-terminal half of RILP mediate interaction with VPS22 and VPS36, respectively. Overexpression of RILP leads to enlarged and clustered MVBs marked by lysobisphosphatidic acid (LBPA). In addition, RILP or its C-terminal fragment causes a retardation of sorting internalized EGF to the degradation route at the level of sorting endosomes marked by EEA1. We propose that RILP-->ESCRT-II serves as a regulatory/feedback loop to govern the coordination of early and late parts of the endocytic pathway.
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Affiliation(s)
- Tuanlao Wang
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Singapore
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110
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Eathiraj S, Mishra A, Prekeris R, Lambright DG. Structural basis for Rab11-mediated recruitment of FIP3 to recycling endosomes. J Mol Biol 2006; 364:121-35. [PMID: 17007872 DOI: 10.1016/j.jmb.2006.08.064] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 08/22/2006] [Accepted: 08/22/2006] [Indexed: 10/24/2022]
Abstract
The Rab11 GTPase regulates recycling of internalized plasma membrane receptors and is essential for completion of cytokinesis. A family of Rab11 interacting proteins (FIPs) that conserve a C-terminal Rab-binding domain (RBD) selectively recognize the active form of Rab11. Normal completion of cytokinesis requires a complex between Rab11 and FIP3. Here, we report the crystal structure and mutational analysis of a heterotetrameric complex between constitutively active Rab11 and a FIP3 construct that includes the RBD. Two Rab11 molecules bind to dyad symmetric sites at the C terminus of FIP3, which forms a non-canonical coiled-coiled dimer with a flared C terminus and hook region. The RBD overlaps with the coiled coil and extends through the C-terminal hook. Although FIP3 engages the switch and interswitch regions of Rab11, the mode of interaction differs significantly from that of other Rab-effector complexes. In particular, the switch II region undergoes a large structural rearrangement from an ordered but non-complementary active conformation to a remodeled conformation that facilitates the interaction with FIP3. Finally, we provide evidence that FIP3 can form homo-oligomers in cells, and that a critical determinant of Rab11 binding in vitro is necessary for FIP3 recruitment to recycling endosomes during cytokinesis.
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Affiliation(s)
- Sudharshan Eathiraj
- Program in Molecular Medicine and Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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111
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Progida C, Spinosa MR, De Luca A, Bucci C. RILP interacts with the VPS22 component of the ESCRT-II complex. Biochem Biophys Res Commun 2006; 347:1074-9. [PMID: 16857164 DOI: 10.1016/j.bbrc.2006.07.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Accepted: 07/05/2006] [Indexed: 01/26/2023]
Abstract
The Rab-interacting lysosomal protein (RILP) has been identified as an effector for the small GTPases Rab7 and Rab34. It has been demonstrated that Rab7 and RILP are key proteins for the biogenesis of lysosomes and phagolysosomes. Indeed, expression of dominant negative mutants of Rab7 or of the C-terminal half of RILP impairs biogenesis and function of these organelles. In this study we have isolated, using the yeast two-hybrid system, the EAP30/SNF8/VPS22 subunit of the ESCRT-II complex as a RILP interacting protein. We demonstrated that VPS22 interacts with the N-terminal half of RILP. The interaction data obtained with the two-hybrid system were confirmed by co-immunoprecipitation. In addition, confocal immunofluorescence revealed colocalization of GFP-RILP and HA-VPS22. These data suggest that RILP could have a role in the biogenesis of multivesicular bodies.
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Affiliation(s)
- Cinzia Progida
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università di Lecce, Via Provinciale Monteroni, 73100 Lecce, Italy
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112
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Abstract
The human genome encodes approximately 70 Rab GTPases that localize to the surfaces of distinct membrane compartments. To investigate the mechanism of Rab localization, chimeras containing heterologous Rab hypervariable domains were generated, and their ability to bind seven Rab effectors was quantified. Two chimeras could bind effectors for two distinctly localized Rabs; a Rab5/9 hybrid bound both Rab5 and Rab9 effectors, and a Rab1/9 hybrid bound to certain Rab1 and Rab9 effectors. These unusual chimeras permitted a test of the importance of effector binding for Rab localization. In both cases, changing the cellular concentration of a key Rab9 effector, which is called tail-interacting protein of 47 kD, moved a fraction of the proteins from their parental Rab localization to that of Rab9. Thus, relative concentrations of certain competing effectors could determine a chimera's localization. These data confirm the importance of effector interactions for Rab9 localization, and support a model in which effector proteins rely on Rabs as much as Rabs rely on effectors to achieve their correct steady state localizations.
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Affiliation(s)
- Dikran Aivazian
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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113
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Marsman M, Jordens I, Rocha N, Kuijl C, Janssen L, Neefjes J. A splice variant of RILP induces lysosomal clustering independent of dynein recruitment. Biochem Biophys Res Commun 2006; 344:747-56. [PMID: 16631113 DOI: 10.1016/j.bbrc.2006.03.178] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Accepted: 03/26/2006] [Indexed: 10/24/2022]
Abstract
The small GTPase Rab7 controls fusion and transport of late endocytic compartments. A critical mediator is the Rab7 effector RILP that recruits the minus-end dynein-dynactin motor complex to these compartments. We identified a natural occurring splice variant of RILP (RILPsv) lacking only 27 amino acids encoded by exon VII. Both variants bind Rab7, prolong its GTP-bound state, and induce clustering of late endocytic compartments. However, RILPsv does not recruit the dynein-dynactin complex, implicating exon VII in motor recruitment. Clustering might still occur via dimerization, since both RILP and RILPsv are able to form hetero- and homo-dimers. Moreover, both effectors compete for Rab7 binding but with different outcome for dynein-dynactin recruitment and transport. Hence, RILPsv provides an extra dimension to the control of vesicle fusion and transport by the small GTPase Rab7.
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Affiliation(s)
- Marije Marsman
- Division of Tumor Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
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114
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Kawasaki M, Nakayama K, Wakatsuki S. Membrane recruitment of effector proteins by Arf and Rab GTPases. Curr Opin Struct Biol 2005; 15:681-9. [PMID: 16289847 DOI: 10.1016/j.sbi.2005.10.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 09/28/2005] [Accepted: 10/21/2005] [Indexed: 01/05/2023]
Abstract
In their GTP-bound form, Arf and Rab family GTPases associate with distinct organelle membranes, to which they recruit specific sets of effector proteins that regulate vesicular transport. The Arf GTPases are involved in the formation of coated carrier vesicles by recruiting coat proteins. On the other hand, the Rab GTPases are involved in the tethering, docking and fusion of transport vesicles with target organelles, acting in concert with the tethering and fusion machineries. Recent structural studies of the Arf1-GGA and Rab5-Rabaptin-5 complexes, as well as other effector structures in complex with the Arf and Rab GTPases, have shed light on the mechanisms underlying the GTP-dependent membrane recruitment of these effector proteins.
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Affiliation(s)
- Masato Kawasaki
- Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
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115
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Colucci AMR, Campana MC, Bellopede M, Bucci C. The Rab-interacting lysosomal protein, a Rab7 and Rab34 effector, is capable of self-interaction. Biochem Biophys Res Commun 2005; 334:128-33. [PMID: 15996637 DOI: 10.1016/j.bbrc.2005.06.067] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 06/14/2005] [Indexed: 11/28/2022]
Abstract
Rab-interacting lysosomal protein (RILP) has been identified as an interacting partner of the small GTPases Rab7 and Rab34. Active Rab7 recruits RILP on the late endosomal/lysosomal membrane and RILP then functions as a Rab7 effector controlling transport to degradative compartments. Indeed, RILP induces recruitment of dynein-dynactin motor complexes to Rab7-containing late endosomes and lysosomes. Recently, Rab7 and RILP have been found to be key proteins also for the biogenesis of phagolysosomes. Therefore, RILP represents probably an important factor for all endocytic routes to lysosomes. In this study, we show, using the yeast two-hybrid system, that RILP is able to interact with itself. The data obtained with the two-hybrid system were confirmed using co-immunoprecipitation in HeLa cells. The data together indicate that RILP, as already demonstrated for several other Rab effector proteins, is capable of self-association, thus probably forming a homo-dimer.
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Affiliation(s)
- Anna Maria Rosaria Colucci
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università degli Studi di Lecce, Via Monteroni, 73100 Lecce, Italy
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