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Campa F, Yoon HY, Ha VL, Szentpetery Z, Balla T, Randazzo PA. A PH domain in the Arf GTPase-activating protein (GAP) ARAP1 binds phosphatidylinositol 3,4,5-trisphosphate and regulates Arf GAP activity independently of recruitment to the plasma membranes. J Biol Chem 2009; 284:28069-28083. [PMID: 19666464 DOI: 10.1074/jbc.m109.028266] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ARAP1 is a phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3))-dependent Arf GTPase-activating protein (GAP) with five PH domains that regulates endocytic trafficking of the epidermal growth factor receptor (EGFR). Two tandem PH domains are immediately N-terminal of the Arf GAP domain, and one of these fits the consensus sequence for PtdIns(3,4,5)P(3) binding. Here, we tested the hypothesis that PtdIns(3,4,5)P(3)-dependent recruitment mediated by the first PH domain of ARAP1 regulates the in vivo and in vitro function of ARAP1. We found that PH1 of ARAP1 specifically bound to PtdIns(3,4,5)P(3), but with relatively low affinity (approximately 1.6 microm), and the PH domains did not mediate PtdIns(3,4,5)P(3)-dependent recruitment to membranes in cells. However, PtdIns(3,4,5)P(3) binding to the PH domain stimulated GAP activity and was required for in vivo function of ARAP1 as a regulator of endocytic trafficking of the EGFR. Based on these results, we propose a variation on the model for the function of phosphoinositide-binding PH domains. In our model, ARAP1 is recruited to membranes independently of PtdIns(3,4,5)P(3), the subsequent production of which triggers enzymatic activity.
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Affiliation(s)
- Fanny Campa
- Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Hye-Young Yoon
- Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Vi Luan Ha
- Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Zsofia Szentpetery
- Program for Developmental Neuroscience, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Tamas Balla
- Program for Developmental Neuroscience, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Paul A Randazzo
- Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892.
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2
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Luo R, Ha VL, Hayashi R, Randazzo PA. Arf GAP2 is positively regulated by coatomer and cargo. Cell Signal 2009; 21:1169-79. [PMID: 19296914 DOI: 10.1016/j.cellsig.2009.03.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 03/05/2009] [Accepted: 03/09/2009] [Indexed: 11/19/2022]
Abstract
Arf GAP2 is one of four Arf GAPs that function in the Golgi apparatus. We characterized the kinetics of Arf GAP2 and its regulation. Purified Arf GAP2 had little activity compared to purified Arf GAP1. Of the potential regulators we examined, coatomer had the greatest effect, stimulating activity one to two orders of magnitude. The effect was biphasic, with half-maximal activation observed at 50 nM coatomer and activation peaking at approximately 150 nM coatomer. Activation by coatomer was greater for Arf GAP2 than has been reported for Arf GAP1. The effects of phosphoinositides and changes in vesicle curvature on GAP activity were small compared to coatomer; however, both increased coatomer-dependent activity. Peptides from p24 cargo proteins increased Arf GAP2 activity by an additional 2- to 4-fold. The effect of cargo peptide was dependent on coatomer. Overexpressing the cargo protein p25 decreased cellular Arf1*GTP levels. The differential sensitivity of Arf GAP1 and Arf GAP2 to coatomer could coordinate their activities. Based on the common regulatory features of Arf GAP1 and 2, we propose a mechanism for cargo selection in which GTP hydrolysis triggered by cargo binding to the coat protein is coupled to coat polymerization.
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Affiliation(s)
- Ruibai Luo
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, MD 20892, USA
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3
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Bowzard JB, Cheng D, Peng J, Kahn RA. ELMOD2 is an Arl2 GTPase-activating protein that also acts on Arfs. J Biol Chem 2007; 282:17568-80. [PMID: 17452337 DOI: 10.1074/jbc.m701347200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulatory GTPases in the Ras superfamily employ a cycle of alternating GTP binding and hydrolysis, controlled by guanine nucleotide exchange factors and GTPase-activating proteins (GAPs), as essential features of their actions in cells. Studies of these GAPs and guanine nucleotide exchange factors have provided important insights into our understanding of GTPase signaling and biology. Within the Ras superfamily, the Arf family is composed of 30 members in mammals, including 22 Arf-like (Arl) proteins. Much less is known about the mechanisms of cell regulation by Arls than by Arfs. We report the purification from bovine testis of an Arl2 GAP and its identity as ELMOD2, a protein with no previously described function. ELMOD2 is one of six human proteins that contain an ELMO domain, and a second member, ELMOD1, was also found to have Arl2 GAP activity. Surprisingly, ELMOD2 also exhibited GAP activity against Arf proteins even though it does not contain the canonical Arf GAP sequence signature. The broader specificity of ELMOD2, as well as the previously described role for ELMO1 and ELMO2 in linking Arf6 and Rac1 signaling, suggests that ELMO family members may play a more general role in integrating signaling pathways controlled by Arls and other GTPases.
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Affiliation(s)
- J Bradford Bowzard
- Department of Biochemistry, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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4
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Luo R, Ahvazi B, Amariei D, Shroder D, Burrola B, Losert W, Randazzo P. Kinetic analysis of GTP hydrolysis catalysed by the Arf1-GTP-ASAP1 complex. Biochem J 2007; 402:439-47. [PMID: 17112341 PMCID: PMC1863566 DOI: 10.1042/bj20061217] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 11/09/2006] [Accepted: 11/20/2006] [Indexed: 11/17/2022]
Abstract
Arf (ADP-ribosylation factor) GAPs (GTPase-activating proteins) are enzymes that catalyse the hydrolysis of GTP bound to the small GTP-binding protein Arf. They have also been proposed to function as Arf effectors and oncogenes. We have set out to characterize the kinetics of the GAP-induced GTP hydrolysis using a truncated form of ASAP1 [Arf GAP with SH3 (Src homology 3) domain, ankyrin repeats and PH (pleckstrin homology) domains 1] as a model. We found that ASAP1 used Arf1-GTP as a substrate with a k(cat) of 57+/-5 s(-1) and a K(m) of 2.2+/-0.5 microM determined by steady-state kinetics and a kcat of 56+/-7 s(-1) determined by single-turnover kinetics. Tetrafluoroaluminate (AlF4-), which stabilizes complexes of other Ras family members with their cognate GAPs, also stabilized a complex of Arf1-GDP with ASAP1. As anticipated, mutation of Arg-497 to a lysine residue affected kcat to a much greater extent than K(m). Changing Trp-479, Iso-490, Arg-505, Leu-511 or Asp-512 was predicted, based on previous studies, to affect affinity for Arf1-GTP. Instead, these mutations primarily affected the k(cat). Mutants that lacked activity in vitro similarly lacked activity in an in vivo assay of ASAP1 function, the inhibition of dorsal ruffle formation. Our results support the conclusion that the Arf GAP ASAP1 functions in binary complex with Arf1-GTP to induce a transition state towards GTP hydrolysis. The results have led us to speculate that Arf1-GTP-ASAP1 undergoes a significant conformational change when transitioning from the ground to catalytically active state. The ramifications for the putative effector function of ASAP1 are discussed.
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Key Words
- arf gap with sh3
- ankyrin repeats and ph domains 1 (asap1)
- adp-ribosylation factor (arf)
- gtpase-activating protein (gap)
- gtp-binding protein
- gtp hydrolysis
- kinetics
- ank, ankyrin repeat
- arf, adp-ribosylation factor
- asap, arf gap with sh3 (src homology 3), anks and ph domains
- dtt, dithiothreitol
- gap, gtpase-activating protein
- gst, glutathione s-transferase
- ha, haemagglutinin
- luvs, large unilamellar vesicles
- myrarf1, myristoylated arf1
- pap, phosphatidic acid phosphohydrolase
- pdgf, platelet-derived growth factor
- ph domain, pleckstrin homology domain
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Affiliation(s)
- Ruibai Luo
- *Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, U.S.A
| | - Bijan Ahvazi
- †National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, MD 20892, U.S.A
| | - Diana Amariei
- *Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, U.S.A
| | - Deborah Shroder
- *Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, U.S.A
| | - Beatriz Burrola
- ‡Department of Physics and IPST (Institute for Physical Sciences and Technology), University of Maryland, College Park, MD 20742, U.S.A
| | - Wolfgang Losert
- ‡Department of Physics and IPST (Institute for Physical Sciences and Technology), University of Maryland, College Park, MD 20742, U.S.A
| | - Paul A. Randazzo
- *Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, U.S.A
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5
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Luo R, Jacques K, Ahvazi B, Stauffer S, Premont RT, Randazzo PA. Mutational analysis of the Arf1*GTP/Arf GAP interface reveals an Arf1 mutant that selectively affects the Arf GAP ASAP1. Curr Biol 2006; 15:2164-9. [PMID: 16332543 DOI: 10.1016/j.cub.2005.10.065] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 10/20/2005] [Accepted: 10/21/2005] [Indexed: 11/21/2022]
Abstract
Arf1 is a GTP binding protein that functions at a number of cellular sites to control membrane traffic and actin remodeling. Arf1 is regulated by site-specific GTPase-activating proteins (GAPs). The combined results of crystallographic and biochemical studies have led to the proposal that Arf1 GAPs differ in the specific interface formed with Arf1. To test this hypothesis, we have used mutagenesis to examine the interaction of three Arf GAPs (ASAP1, AGAP1, and ArfGAP1) with switch 1, switch 2, and alpha helix3 of Arf1. The GAPs were similar in being affected by mutations in switch 1 and 2. However, effects of a mutation within alpha helix3 and specific mutations within switch 1 and 2 differed among the GAPs. The largest differences were observed with a change of isoleucine 46 to aspartate ([I46D]Arf1), which reduced ASAP1-induced catalysis by approximately 10,000-fold but had a 3-fold effect on AGAP1. The reduction was due to an isolated effect on the catalytic rate, k(cat). In vivo [I46D]Arf1 had no detectable effect on the Golgi apparatus but, instead, functioned as a constitutively active mutant in the cell periphery, affecting the localization of ASAP1 and paxillin. Based on our results, we conclude that the contribution of specific residues within switch 1 of Arf to binding and achieving a transition state toward GTP hydrolysis differs among Arf GAPs.
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Affiliation(s)
- Ruibai Luo
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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6
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Gizachew D, Oswald R. NMR structural studies of the myristoylated N-terminus of ADP ribosylation factor 6 (Arf6). FEBS Lett 2006; 580:4296-301. [PMID: 16839550 DOI: 10.1016/j.febslet.2006.06.086] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 06/28/2006] [Accepted: 06/29/2006] [Indexed: 10/24/2022]
Abstract
Arf proteins are guanine nucleotide binding proteins that are implicated in endocytotic pathways and vesicle trafficking. The two widely studied isoforms of Arf proteins (Arf1 and Arf6) have different cellular functions and localizations but similar structures. Arf proteins have an N-terminal helix with a covalently bound myristoyl group. Except structural models, there are no three dimensional structures of the myristoylated N-terminal peptide or the intact myristoylated Arf proteins. However, understanding the role of both the myristoyl group and the N-terminal helix based on the details of their molecular structures is of great interest. In the solution structure of myristoylated N-terminal peptide of Arf6 described here, the myristoyl group folds toward the N-terminus to interact with the hydrophobic residues in particular, the phenyl ring. Also, the structure of the dodecylphosphocholine (DPC) micelle-bound of the peptide together with paramagnetic studies showed that the myristoyl group is inserted into the micelle while residues V4-G10 interact with the surface of the micelle. The structural differences between the unbound and micelle-bound myristoylated N-terminal peptide of Arf6 involves the myristoyl group and the side chains of the hydrophobic residues.
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Affiliation(s)
- Dawit Gizachew
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA.
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7
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Ye K. PIKE GTPase-mediated nuclear signalings promote cell survival. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:570-6. [PMID: 16567124 DOI: 10.1016/j.bbalip.2006.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 02/19/2006] [Accepted: 02/20/2006] [Indexed: 10/24/2022]
Abstract
The nuclear GTPase PIKE (PI 3-kinase Enhancer) binds PI 3-kinase and enhances it lipid kinase activity. PIKE predominantly distributes in the brain, and nerve growth factor stimulation triggers PIKE activation by provoking nuclear translocation of PLC-gamma1, which acts as a physiologic guanine nucleotide exchange factor (GEF) for PIKE through its SH3 domain. PIKE contains GTPase and ArfGAP domains, which are separated by a PH domain. C-terminal ArfGAP domain activates its internal GTPase activity, and this process is regulated by the interaction between phosphatidylinositols and PH domain. PI 3-kinase occurs in the nuclei of a broad range of cell types, and various stimuli elicit its nuclear translocation. The nuclei from NGF-treated PC12 cells are resistant to DNA fragmentation initiated by activated cell-free apoptosome, for which PIKE/nuclear PI 3-kinase signaling through nuclear PI(3,4,5)P(3) and Akt plays an essential role. As a nuclear receptor for PI(3,4,5)P(3,) B23 binds to PI(3,4,5)P(3) in an NGF-dependent way. The PI(3,4,5)P(3)/B23 complex inhibits DNA fragmentation activity of CAD. Nuclear Akt regulation of apoptosis is dependent on its phosphorylation of key substrates in the nucleus, but the identities of these substrates are unknown. Identification of its nuclear substrates will further our understanding of the physiological roles of nuclear PI 3-kinase/Akt signaling.
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Affiliation(s)
- Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
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8
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Kakhlon O, Sakya P, Larijani B, Watson R, Tooze SA. GGA function is required for maturation of neuroendocrine secretory granules. EMBO J 2006; 25:1590-602. [PMID: 16601685 PMCID: PMC1440831 DOI: 10.1038/sj.emboj.7601067] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Accepted: 03/08/2006] [Indexed: 11/08/2022] Open
Abstract
Secretory granule (SG) maturation has been proposed to involve formation of clathrin-coated vesicles (CCVs) from immature SGs (ISGs). We tested the effect of inhibiting CCV budding by using the clathrin adaptor GGA (Golgi-associated, gamma-ear-containing, ADP-ribosylation factor-binding protein) on SG maturation in neuroendocrine cells. Overexpression of a truncated, GFP-tagged GGA, VHS (Vps27, Hrs, Stam)-GAT (GGA and target of myb (TOM))-GFP led to retention of MPR, VAMP4, and syntaxin 6 in mature SGs (MSGs), suggesting that CCV budding from ISGs is inhibited by the SG-localizing VHS-GAT-GFP. Furthermore, VHS-GAT-GFP-overexpression disrupts prohormone convertase 2 (PC2) autocatalytic cleavage, processing of secretogranin II to its product p18, and the correlation between PC2 and p18 levels. All these effects were not observed if full-length GGA1-GFP was overexpressed. Neither GGA1-GFP nor VHS-GAT-GFP perturbed SG protein budding from the TGN, or homotypic fusion of ISGs. Reducing GGA3 levels by using short interfering (si)RNA also led to VAMP4 retention in SGs, and inhibition of PC2 activity. Our results suggest that inhibition of CCV budding from ISGs downregulates the sorting from the ISGs and perturbs the intragranular activity of PC2.
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Affiliation(s)
- Or Kakhlon
- Secretory Pathway Laboratories, Cancer Research UK, London Research Institute, London, UK
| | - Prabhat Sakya
- Cell Biophysics, Cancer Research UK, London Research Institute, London, UK
| | - Banafshe Larijani
- Cell Biophysics, Cancer Research UK, London Research Institute, London, UK
| | - Rose Watson
- Electron Microscopy Laboratories, Cancer Research UK, London Research Institute, London, UK
| | - Sharon A Tooze
- Secretory Pathway Laboratories, Cancer Research UK, London Research Institute, London, UK
- Secretory Pathway Laboratories, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK. Tel.: +44 207 269 3122; Fax: +44 207 269 3417; E-mail:
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9
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Abstract
ADP-ribosylation factor 1 (Arf1) is a GTP-binding protein that regulates membrane traffic. This function of Arf1 is, at least in part, mediated by Arf1 x GTP binding to coat proteins such as coatomer, clathrin adaptor protein (AP) complexes 1 and 3, and gamma-adaptin homology-Golgi associated Arf-binding (GGA) proteins. Binding to Arf1 x GTP recruits these coat proteins to membranes, leading to the formation of transport vesicles. Whereas coatomer and the AP complexes are hetero-oligomers, GGAs are single polypeptide chains. Therefore, working with recombinant GGAs is straightforward compared to the other Arf1 effectors. Consequently, the GGAs have been used as a model for studying Arf1 interactions with effectors and as reagents to determine Arf1 x GTP levels in cells. In this chapter, we describe in vitro assays for analysis of GGA interaction with Arf1 x GTP and for determining intracellular Arf1 x GTP levels.
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Affiliation(s)
- Hye-Young Yoon
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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10
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Hu Y, Liu Z, Ye K. Phosphoinositol lipids bind to phosphatidylinositol 3 (PI3)-kinase enhancer GTPase and mediate its stimulatory effect on PI3-kinase and Akt signalings. Proc Natl Acad Sci U S A 2005; 102:16853-8. [PMID: 16263930 PMCID: PMC1283830 DOI: 10.1073/pnas.0507365102] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylinositol 3 (PI3)-kinase enhancer (PIKE) is a nuclear GTPase that enhances PI3-kinase activity in a GTP-dependent manner. Both PIKE-L and -A isoforms contain GTPase, pleckstrin homology (PH), ADP ribosylation factor-GTPase-activating protein, and two ankyrin repeats domains, and C-terminal ADP ribosylation factor-GTPase-activating protein activates its internal GTPase activity. However, whether PH domain modulates the intramolecular action and subsequently influences its downstream signalings remains elusive. Here we show that PH domain from PIKE-L robustly binds PI(3,4,5)P(3) and exclusively resides in the nucleus. By contrast, the mutant (K679,687N), unable to bind phosphoinositol lipids, translocates to the cytoplasm. This mutation substantially compromises the stimulatory effects on PI3-kinase by PIKE-L. Surprisingly, PH domain from PIKE-A distributes in the cytoplasm. Similar mutation in PH domain of PIKE-A abolishes its binding to PI(3,4,5)P(3) and significantly decreases its activation of Akt. Moreover, amplified PIKE-A from human cancers contains mutations and highly stimulates Akt kinase activity, correlating with its GTPase activity. Thus, phosphatidylinositols regulate PIKE GTPase activity, mediating its downstream PI3-kinase/Akt signaling through a feedback mechanism by binding to its PH domain.
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Affiliation(s)
- Yuanxin Hu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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11
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Liu YW, Huang CF, Huang KB, Lee FJS. Role for Gcs1p in regulation of Arl1p at trans-Golgi compartments. Mol Biol Cell 2005; 16:4024-33. [PMID: 15975906 PMCID: PMC1196316 DOI: 10.1091/mbc.e05-01-0023] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
ADP-ribosylation factor (ARF) and ARF-like (ARL) proteins are members of the ARF family, which are critical components of several different vesicular trafficking pathways. ARFs have little or no detectable GTPase activity without the assistance of a GTPase-activating protein (GAP). Here, we demonstrate that yeast Gcs1p exhibits GAP activity toward Arl1p and Arf1p in vitro, and Arl1p can interact with Gcs1p in a GTP-dependent manner. Arl1p was observed both on trans-Golgi and in cytosol and was recruited from cytosol to membranes in a GTP-dependent manner. In gcs1 mutant cells, the fraction of Arl1p in cytosol relative to trans-Golgi was less than it was in wild-type cells. Increasing Gcs1p levels returned the distribution toward that of wild-type cells. Both Arl1p and Gcs1p influenced the distribution of Imh1p, an Arl1p effector. Our data are consistent with the conclusion that Arl1p moves in a dynamic equilibrium between trans-Golgi and cytosol, and the release of Arl1p from membranes in cells requires the hydrolysis of bound GTP, which is accelerated by Gcs1p.
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Affiliation(s)
- Ya-Wen Liu
- Institute of Molecular Medicine, College of Medicine, and Department of Medical Research, National Taiwan University Hospital, National Taiwan University, Taipei 100, Taiwan
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12
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Harroun TA, Bradshaw JP, Balali-Mood K, Katsaras J. A structural study of the myristoylated N-terminus of ARF1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1668:138-44. [PMID: 15670739 DOI: 10.1016/j.bbamem.2004.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Revised: 12/01/2004] [Accepted: 12/02/2004] [Indexed: 11/18/2022]
Abstract
The effect of myristoylation on the 15-amino-acid peptide from the membrane-binding N-terminus of ADP ribosylation factor 1 (ARF1) was studied using neutron diffraction and circular dichroism. A previous study on the non-acylated form indicated that the peptide lies parallel to the membrane, at a shallow depth and in the vicinity of the phosphorylcholine headgroups. It was suggested that the helix does not extend past residue 12, an important consequence for the linking region of the ARF1 protein. In this paper, we show that the result of myristoylation is to increase the helical content reaching the peptide's C-terminus, resulting in the formation of a new hydrophobic face. This increased helicity may augment the entire protein's membrane-binding affinity, indicating that ARF1 effectively has two interdependent membrane-binding motifs.
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Affiliation(s)
- Thad A Harroun
- National Research Council, Neutron Program for Materials Research, Chalk River Laboratories, Chalk River, ON, Canada K0J 1J0.
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14
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Godi A, Di Campli A, Konstantakopoulos A, Di Tullio G, Alessi DR, Kular GS, Daniele T, Marra P, Lucocq JM, De Matteis MA. FAPPs control Golgi-to-cell-surface membrane traffic by binding to ARF and PtdIns(4)P. Nat Cell Biol 2004; 6:393-404. [PMID: 15107860 DOI: 10.1038/ncb1119] [Citation(s) in RCA: 588] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Accepted: 03/08/2004] [Indexed: 11/09/2022]
Abstract
The molecular mechanisms underlying the formation of carriers trafficking from the Golgi complex to the cell surface are still ill-defined; nevertheless, the involvement of a lipid-based machinery is well established. This includes phosphatidylinositol 4-phosphate (PtdIns(4)P), the precursor for phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)). In yeast, PtdIns(4)P exerts a direct role, however, its mechanism of action and its targets in mammalian cells remain uncharacterized. We have identified two effectors of PtdIns(4)P, the four-phosphate-adaptor protein 1 and 2 (FAPP1 and FAPP2). Both proteins localize to the trans-Golgi network (TGN) on nascent carriers, and interact with PtdIns(4)P and the small GTPase ADP-ribosylation factor (ARF) through their plekstrin homology (PH) domain. Displacement or knockdown of FAPPs inhibits cargo transfer to the plasma membrane. Moreover, overexpression of FAPP-PH impairs carrier fission. Therefore, FAPPs are essential components of a PtdIns(4)P- and ARF-regulated machinery that controls generation of constitutive post-Golgi carriers.
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Affiliation(s)
- Anna Godi
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, via Nazionale, 66030 Santa Maria Imbaro (CH), Italy
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15
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Randazzo PA, Hirsch DS. Arf GAPs: multifunctional proteins that regulate membrane traffic and actin remodelling. Cell Signal 2004; 16:401-13. [PMID: 14709330 DOI: 10.1016/j.cellsig.2003.09.012] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ADP-ribosylation factor (Arf) Arf GTPase-activating proteins (GAPs) are a family of proteins that induce hydrolysis of GTP bound to Arf. A conserved domain containing a zinc finger motif mediates catalysis. The substrate, Arf.GTP, affects membrane trafficking and actin remodelling. Consistent with activity as an Arf regulator, the Arf GAPs affect both of these pathways. However, the Arf GAPs are likely to have Arf-independent activities that contribute to their cellular functions. Structures of the Arf GAPs are diverse containing catalytic, protein-protein interaction and lipid interaction domains in addition to the Arf GAP domain. Some Arf GAPs have been identified and characterized on the basis of activities other than Arf GAP. Here, we describe the Arf GAP family, enzymology of some members of the Arf GAP family and known functions of the proteins. The results discussed illustrate roles for both Arf-dependent and -independent activities in the regulation of cellular architecture.
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Affiliation(s)
- Paul A Randazzo
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Building. 37 Room 4118, Bethesda, MD 20892, USA.
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16
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Abstract
The GGA proteins are a family of ubiquitously expressed, Arf-dependent clathrin adaptors that mediate the sorting of mannose-6-phosphate receptors between the trans-Golgi network and endosomes. Recent studies have elucidated the biochemical and structural bases for the interaction of the GGA proteins with many binding partners, and have shed light on the molecular and cellular mechanisms by which the GGA proteins participate in protein sorting.
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Affiliation(s)
- Juan S Bonifacino
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Building 18T/Room 101, National Institutes of Health, Bethesda, Maryland 20892, USA.
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17
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Abstract
Arf GTP-binding proteins regulate membrane traffic and actin remodeling. Similar to other GTP-binding proteins, a complex of Arf-GTP with an effector protein mediates Arf function. Arf interacts with at least three qualitatively different types of effectors. First, it interacts with structural proteins, the vesicle coat proteins. The second type of effector is lipid-metabolizing enzymes, and the third comprises those proteins that bind to Arf-GTP but whose biochemical or biological functions are not yet clearly defined. Arf interacts with two other families of proteins, the exchange factors and the GTPase-activating proteins. Recent work examining the functional relationships among the diverse Arf interactors has led to reconsideration of the prevailing paradigms for Arf action.
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Affiliation(s)
- Zhongzhen Nie
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Building 37, Room 4118, Bethesda, MD 20892, USA
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18
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Shiba T, Kawasaki M, Takatsu H, Nogi T, Matsugaki N, Igarashi N, Suzuki M, Kato R, Nakayama K, Wakatsuki S. Molecular mechanism of membrane recruitment of GGA by ARF in lysosomal protein transport. Nat Struct Mol Biol 2003; 10:386-93. [PMID: 12679809 DOI: 10.1038/nsb920] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Accepted: 03/19/2003] [Indexed: 11/09/2022]
Abstract
GGAs are critical for trafficking soluble proteins from the trans-Golgi network (TGN) to endosomes/lysosomes through interactions with TGN-sorting receptors, ADP-ribosylation factor (ARF) and clathrin. ARF-GTP bound to TGN membranes recruits its effector GGA by binding to the GAT domain, thus facilitating recognition of GGA for cargo-loaded receptors. Here we report the X-ray crystal structures of the human GGA1-GAT domain and the complex between ARF1-GTP and the N-terminal region of the GAT domain. When unbound, the GAT domain forms an elongated bundle of three a-helices with a hydrophobic core. Structurally, this domain, combined with the preceding VHS domain, resembles CALM, an AP180 homolog involved in endocytosis. In the complex with ARF1-GTP, a helix-loop-helix of the N-terminal part of GGA1-GAT interacts with the switches 1 and 2 of ARF1 predominantly in a hydrophobic manner. These data reveal a molecular mechanism underlying membrane recruitment of adaptor proteins by ARF-GTP.
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Affiliation(s)
- Tomoo Shiba
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
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19
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Suer S, Misra S, Saidi LF, Hurley JH. Structure of the GAT domain of human GGA1: a syntaxin amino-terminal domain fold in an endosomal trafficking adaptor. Proc Natl Acad Sci U S A 2003; 100:4451-6. [PMID: 12668765 PMCID: PMC404691 DOI: 10.1073/pnas.0831133100] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2003] [Accepted: 02/26/2003] [Indexed: 12/28/2022] Open
Abstract
The Golgi-associated, gamma-adaptin homologous, ADP-ribosylation factor (ARF)-interacting proteins (GGAs) are adaptors that sort receptors from the trans-Golgi network into the endosomallysosomal pathway. The GGAs and TOM1 (GAT) domains of the GGAs are responsible for their ARF-dependent localization. The 2.4-A crystal structure of the GAT domain of human GGA1 reveals a three-helix bundle, with a long N-terminal helical extension that is not conserved in GAT domains that do not bind ARF. The ARF binding site is located in the N-terminal extension and is separate from the core three-helix bundle. An unanticipated structural similarity to the N-terminal domain of syntaxin 1a was discovered, comprising the entire three-helix bundle. A conserved binding site on helices 2 and 3 of the GAT domain three-helix bundle is predicted to interact with coiled-coil-containing proteins. We propose that the GAT domain is descended from the same ancestor as the syntaxin 1a N-terminal domain, and that both protein families share a common function in binding coiled-coil domain proteins.
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Affiliation(s)
- Silke Suer
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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20
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Collins BM, Watson PJ, Owen DJ. The structure of the GGA1-GAT domain reveals the molecular basis for ARF binding and membrane association of GGAs. Dev Cell 2003; 4:321-32. [PMID: 12636914 DOI: 10.1016/s1534-5807(03)00037-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The GGAs are a family of clathrin adaptor proteins involved in vesicular transport between the trans-Golgi network and endosomal system. Here we confirm reports that GGAs are targeted to the Golgi via interaction between the GGA-GAT domain and ARF-GTP, and we present the structure of the GAT domain of human GGA1, completing the structural description of the folded domains of GGA proteins. The GGA-GAT domain possesses an all alpha-helical fold with a "paper clip" topology comprising two independent subdomains. Structure-based mutagenesis demonstrates that ARF1-GTP binding by GGAs is exclusively governed by the N-terminal "hook" subdomain, and, using an in vitro recruitment assay, we show that ARF-GTP binding by this small structure is required and sufficient for Golgi targeting of GGAs.
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Affiliation(s)
- Brett M Collins
- Department of Clinical Biochemistry, University of Cambridge, Hills Road, CB2 2XY, Cambridge, United Kingdom.
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21
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Hirsch DS, Stanley KT, Chen LX, Jacques KM, Puertollano R, Randazzo PA. Arf regulates interaction of GGA with mannose-6-phosphate receptor. Traffic 2003; 4:26-35. [PMID: 12535273 DOI: 10.1034/j.1600-0854.2003.40105.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The role of ADP-ribosylation factor (Arf) in Golgi associated, gamma-adaptin homologous, Arf-interacting protein (GGA)-mediated membrane traffic was examined. GGA is a clathrin adaptor protein that binds Arf through its GAT domain and the mannose-6-phosphate receptor through its VHS domain. The GAT and VHS domains interacted such that Arf and mannose-6-phosphate receptor binding to GGA were mutually exclusive. In vivo, GGA bound membranes through either Arf or mannose-6-phosphate receptor. However, mannose-6-phosphate receptor excluded Arf from GGA-containing structures outside of the Golgi. These data are inconsistent with predictions based on the model for Arf's role in COPI veside coat function. We propose that Arf recruits GGA to a membrane and then, different from the current model, 'hands-off' GGA to mannose-6-phosphate receptor. GGA and mannose-6-phosphate receptor are then incorporated into a transport intermediate that excludes Arf.
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Affiliation(s)
- Dianne Snow Hirsch
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bldg 37 Room 6032 and Cell Biology and Metabolism Branch, National Institute of Child Health and Development, National Institutes of Health, Bethesda. MD 20892, USA
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22
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Nakayama K, Wakatsuki S. The Structure and Function of GGAs, the Traffic Controllers at the TGN Sorting Crossroads. Cell Struct Funct 2003; 28:431-42. [PMID: 14745135 DOI: 10.1247/csf.28.431] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
GGAs (Golgi-localizing, gamma-adaptin ear homology domain, ARF-binding proteins) are a family of monomeric clathrin adaptor proteins that are conserved from yeasts to humans. Data published during the past four years have provided detailed pictures of the localization, domain organization and structure-function relationships of GGAs. GGAs possess four conserved functional domains, each of which interacts with cargo proteins including mannose 6-phosphate receptors, the small GTPase ARF, clathrin, or accessory proteins including Rabaptin-5 and gamma-synergin. Together with or independent of the adaptor protein complex AP-1, GGAs regulate selective transport of cargo proteins, such as mannose 6-phosphate receptors, from the trans-Golgi network to endosomes mediated by clathrin-coated vesicles.
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Affiliation(s)
- Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan.
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