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Freckelton ML, Nedved BT, Cai YS, Cao S, Turano H, Alegado RA, Hadfield MG. Bacterial lipopolysaccharide induces settlement and metamorphosis in a marine larva. Proc Natl Acad Sci U S A 2022; 119:e2200795119. [PMID: 35467986 PMCID: PMC9651628 DOI: 10.1073/pnas.2200795119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/16/2022] [Indexed: 08/09/2023] Open
Abstract
New surfaces in the sea are quickly populated by dense communities of invertebrate animals, whose establishment and maintenance require site-specific settlement of larvae from the plankton. Larvae selectively settle in sites where they can metamorphose and thrive largely due to inductive cues from bacteria residing on these surfaces. However, the nature of the cues used to identify “right places” has remained enigmatic. Here, we demonstrate that lipopolysaccharide, the main component of the outer membrane of Gram-negative bacteria from the bacterium Cellulophaga lytica , induces metamorphosis for a marine worm. We then discuss the likelihood that lipopolysaccharide provides the variation necessary to explain settlement site selectivity for many of the bottom-living invertebrate animals that metamorphose in response to bacterial biofilms. How larvae of the many phyla of marine invertebrates find places appropriate for settlement, metamorphosis, growth, and reproduction is an enduring question in marine science. Biofilm-induced metamorphosis has been observed in marine invertebrate larvae from nearly every major marine phylum. Despite the widespread nature of this phenomenon, the mechanism of induction remains poorly understood. The serpulid polychaete Hydroides elegans is a well established model for investigating bacteria-induced larval development. A broad range of biofilm bacterial species elicit larval metamorphosis in H. elegans via at least two mechanisms, including outer membrane vesicles (OMVs) and complexes of phage-tail bacteriocins. We investigated the interaction between larvae of H. elegans and the inductive bacterium Cellulophaga lytica , which produces an abundance of OMVs but not phage-tail bacteriocins. We asked whether the OMVs of C. lytica induce larval settlement due to cell membrane components or through delivery of specific cargo. Employing a biochemical structure–function approach with a strong ecological focus, the cells and OMVs produced by C. lytica were interrogated to determine the class of the inductive compounds. Here, we report that larvae of H. elegans are induced to metamorphose by lipopolysaccharide produced by C. lytica . The widespread prevalence of lipopolysaccharide and its associated taxonomic and structural variability suggest it may be a broadly employed cue for bacterially induced larval settlement of marine invertebrates.
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Affiliation(s)
| | - Brian T. Nedved
- Kewalo Marine Laboratory, University of Hawaiʻi, Honolulu, HI 96813
| | - You-Sheng Cai
- Department of Pharmaceutical Sciences, Daniel K. Inouye College of Pharmacy, University of Hawaiʻi at Hilo, Hilo, HI 96720
- Department of Nephrology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, People’s Republic of China
| | - Shugeng Cao
- Department of Pharmaceutical Sciences, Daniel K. Inouye College of Pharmacy, University of Hawaiʻi at Hilo, Hilo, HI 96720
| | - Helen Turano
- Department of Oceanography, University of Hawaiʻi Mānoa, Honolulu, HI 96813
| | - Rosanna A. Alegado
- Department of Oceanography, University of Hawaiʻi Mānoa, Honolulu, HI 96813
- Sea Grant College Program, University of Hawaiʻi Mānoa, Honolulu, HI 96813
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Booth A, Marklew CJ, Ciani B, Beales PA. The influence of phosphatidylserine localisation and lipid phase on membrane remodelling by the ESCRT-II/ESCRT-III complex. Faraday Discuss 2021; 232:188-202. [PMID: 34590635 DOI: 10.1039/d0fd00042f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The endosomal sorting complex required for transport (ESCRT) organises in supramolecular structures on the surface of lipid bilayers to drive membrane invagination and scission of intraluminal vesicles (ILVs), a process also controlled by membrane mechanics. However, ESCRT association with the membrane is also mediated by electrostatic interactions with anionic phospholipids. Phospholipid distribution within natural biomembranes is inhomogeneous due to, for example, the formation of lipid rafts and curvature-driven lipid sorting. Here, we have used phase-separated giant unilamellar vesicles (GUVs) to investigate the link between phosphatidylserine (PS)-rich lipid domains and ESCRT activity. We employ GUVs composed of phase separating lipid mixtures, where unsaturated DOPS and saturated DPPS lipids are incorporated individually or simultaneously to enhance PS localisation in liquid disordered (Ld) and/or liquid ordered (Lo) domains, respectively. PS partitioning between the coexisting phases is confirmed by a fluorescent Annexin V probe. Ultimately, we find that ILV generation promoted by ESCRTs is significantly enhanced when PS lipids localise within Ld domains. However, the ILVs that form are rich in Lo lipids. We interpret this surprising observation as preferential recruitment of the Lo phase beneath the ESCRT complex due to its increased rigidity, where the Ld phase is favoured in the neck of the resultant buds to facilitate the high membrane curvature in these regions of the membrane during the ILV formation process. Ld domains offer lower resistance to membrane bending, demonstrating a mechanism by which the composition and mechanics of membranes can be coupled to regulate the location and efficiency of ESCRT activity.
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Affiliation(s)
- Andrew Booth
- School of Chemistry, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Christopher J Marklew
- Department of Chemistry, Centre for Membrane Interactions and Dynamics, University of Sheffield, Sheffield S3 7HF, UK
| | - Barbara Ciani
- Department of Chemistry, Centre for Membrane Interactions and Dynamics, University of Sheffield, Sheffield S3 7HF, UK
| | - Paul A Beales
- School of Chemistry, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK. .,Bragg Centre for Materials Research, University of Leeds, Leeds, LS2 9JT, UK
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Phoenix DA, Harris F, Mura M, Dennison SR. The increasing role of phosphatidylethanolamine as a lipid receptor in the action of host defence peptides. Prog Lipid Res 2015; 59:26-37. [PMID: 25936689 DOI: 10.1016/j.plipres.2015.02.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 01/04/2023]
Abstract
Host defence peptides (HDPs) are antimicrobial agents produced by organisms across the prokaryotic and eukaryotic kingdoms. Many prokaryotes produce HDPs, which utilise lipid and protein receptors in the membranes of bacterial competitors to facilitate their antibacterial action and thereby survive in their niche environment. As a major example, it is well established that cinnamycin and duramycins from Streptomyces have a high affinity for phosphatidylethanolamine (PE) and exhibit activity against other Gram-positive organisms, such as Bacillus. In contrast, although eukaryotic HDPs utilise membrane interactive mechanisms to facilitate their antimicrobial activity, the prevailing view has long been that these mechanisms do not involve membrane receptors. However, this view has been recently challenged by reports that a number of eukaryotic HDPs such as plant cyclotides also use PE as a receptor to promote their antimicrobial activities. Here, we review current understanding of the mechanisms that underpin the use of PE as a receptor in the antimicrobial and other biological actions of HDPs and describe medical and biotechnical uses of these peptides, which range from tumour imaging and detection to inclusion in topical microbicidal gels to prevent the sexual transmission of HIV.
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Affiliation(s)
- David A Phoenix
- School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, UK.
| | - Frederick Harris
- School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, UK; School of Forensic and Investigative Science, University of Central Lancashire, Preston PR1 2HE, UK
| | - Manuela Mura
- School of Mathematics and Physics, College of Science, University of Lincoln, Brayford Pool, Lincoln, Lincolnshire LN6 7TS, UK
| | - Sarah R Dennison
- School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, UK; School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK
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Tripathi T, Smith AD, Abdi M, Alizadeh H. Acanthamoeba-cytopathic protein induces apoptosis and proinflammatory cytokines in human corneal epithelial cells by cPLA2α activation. Invest Ophthalmol Vis Sci 2012; 53:7973-82. [PMID: 23132804 DOI: 10.1167/iovs.12-10436] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
PURPOSE We have shown that Acanthamoeba interacts with a mannosylated protein on corneal epithelial cells and stimulates trophozoites to secrete a mannose-induced 133 kDa protease (MIP-133), which facilitates corneal invasion and induces apoptosis. The mechanism of MIP-133-induced apoptosis is unknown. The aim of this study was to determine if MIP-133 induces apoptosis and proinflammatory cytokines/chemokines in human corneal epithelial (HCE) cells via the cytosolic phospholipase A(2α) (cPLA(2α)) pathway. METHODS HCE cells were incubated with or without MIP-133 at doses of 7.5, 15, and 50 μg/mL for 6, 12, and 24 hours. The effects of cPLA(2α) inhibitors on cPLA(2α), arachidonic acid (AA) release, and apoptosis were tested in vitro. Inhibition of cPLA(2α) involved preincubating HCE cells for 1 hour with cPLA(2α) inhibitors (10 μM methyl-arachidonyl fluorophosphonate [MAFP] or 20 μM arachidonyl trifluoromethyl ketone [AACOCF3]) with or without MIP-133 for 24 hours. Expression of cPLA(2α) mRNA and enzyme was examined by RT-PCR and cPLA(2) activity assays, respectively. Apoptosis of corneal epithelial cells was determined by caspase-3 and DNA fragmentation assays. Expression of IL-8, IL-6, IL-1β, and IFN-γ was examined by RT-PCR and ELISA. RESULTS MIP-133 induced significant cPLA(2α) (approximately two to four times) and AA release (approximately six times) from corneal cells while cPLA(2α) inhibitors significantly reduced cPLA(2α) (approximately two to four times) and AA release (approximately three times) (P < 0.05). cPLA(2α) inhibitors significantly inhibited MIP-133-induced DNA fragmentation approximately 7 to 12 times in HCE cells (P < 0.05). MIP-133 specifically activates cPLA(2α) enzyme activity in HCE cells, which is blocked by preincubation with anti-MIP-133 antibody. In addition, MIP-133 induced significant IL-8, IL-6, IL-1β, and IFN-γ production, approximately two to three times (P < 0.05). CONCLUSIONS MIP-133 interacts with phospholipids on plasma membrane of HCE cells and activates cPLA(2α). cPLA(2α) is involved in apoptosis, AA release, and activation of proinflammatory cytokines/chemokines from HCE cells. cPLA(2α) inhibitors may be a therapeutic target in Acanthamoeba keratitis.
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Affiliation(s)
- Trivendra Tripathi
- Department of Cell Biology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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Aghazadeh Y, Rone MB, Blonder J, Ye X, Veenstra TD, Hales DB, Culty M, Papadopoulos V. Hormone-induced 14-3-3γ adaptor protein regulates steroidogenic acute regulatory protein activity and steroid biosynthesis in MA-10 Leydig cells. J Biol Chem 2012; 287:15380-94. [PMID: 22427666 DOI: 10.1074/jbc.m112.339580] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cholesterol is the sole precursor of steroid hormones in the body. The import of cholesterol to the inner mitochondrial membrane, the rate-limiting step in steroid biosynthesis, relies on the formation of a protein complex that assembles at the outer mitochondrial membrane called the transduceosome. The transduceosome contains several mitochondrial and cytosolic components, including the steroidogenic acute regulatory protein (STAR). Human chorionic gonadotropin (hCG) induces de novo synthesis of STAR, a process shown to parallel maximal steroid production. In the hCG-dependent steroidogenic MA-10 mouse Leydig cell line, the 14-3-3γ protein was identified in native mitochondrial complexes by mass spectrometry and immunoblotting, and its levels increased in response to hCG treatment. The 14-3-3 proteins bind and regulate the activity of many proteins, acting via target protein activation, modification and localization. In MA-10 cells, cAMP induces 14-3-3γ expression parallel to STAR expression. Silencing of 14-3-3γ expression potentiates hormone-induced steroidogenesis. Binding motifs of 14-3-3γ were identified in components of the transduceosome, including STAR. Immunoprecipitation studies demonstrate a hormone-dependent interaction between 14-3-3γ and STAR that coincides with reduced 14-3-3γ homodimerization. The binding site of 14-3-3γ on STAR was identified to be Ser-194 in the STAR-related sterol binding lipid transfer (START) domain, the site phosphorylated in response to hCG. Taken together, these results demonstrate that 14-3-3γ negatively regulates steroidogenesis by binding to Ser-194 of STAR, thus keeping STAR in an unfolded state, unable to induce maximal steroidogenesis. Over time 14-3-3γ homodimerizes and dissociates from STAR, allowing this protein to induce maximal mitochondrial steroid formation.
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Affiliation(s)
- Yasaman Aghazadeh
- The Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal, Quebec H3G 1A4, Canada
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Lipid based therapy for ulcerative colitis-modulation of intestinal mucus membrane phospholipids as a tool to influence inflammation. Int J Mol Sci 2010; 11:4149-64. [PMID: 21152327 PMCID: PMC2996791 DOI: 10.3390/ijms11104149] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 10/15/2010] [Accepted: 10/16/2010] [Indexed: 02/06/2023] Open
Abstract
Ulcerative colitis (UC) is the result of an inappropriate colonic inflammatory response triggered by environmental and genetic factors. We have recently shown that mucus from UC patients has a decreased phosphatidylcholine (PC) content, while clinical trials revealed that therapeutic addition of PC to the colonic mucus alleviated the inflammatory activity. The mechanisms behind this are still unclear. We hypothesized that PC has at least two possible functions in the intestine: First, it establishes the surface hydrophobicity of the mucus and therefore protects the underlying tissue against intraluminal aggressors; recent experiments on surgical specimens revealed reduced surface tension and hydrophobicity in UC patients. Second, mucus phospholipids might also be integrated into the plasma membranes of enterocytes and thereby influence the signaling state of the mucosa. PC has been shown to inhibit TNF-α induced pro-inflammatory responses including: (1) assembly of plasma membrane actin; (2) activation of MAP kinases ERK and p38; and (3) activation of NF-κB and synthesis of pro-inflammatory gene products. Other phospholipids like phosphatidylethanolamine or sphingomyelin had no effect. PC also inhibited latex bead phagosome actin assembly, killing of M. tuberculosis in macrophages, and sphingosine-1-phosphate induced actin assembly in macrophages. Collectively, these results provide a molecular foundation that shows PC, firstly, as an anti-inflammatory, and secondly, as a surface hydrophobicity increasing compound with promising therapeutic potential in the treatment of inflammatory bowel disease.
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Ehehalt R, Braun A, Karner M, Füllekrug J, Stremmel W. Phosphatidylcholine as a constituent in the colonic mucosal barrier--physiological and clinical relevance. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:983-93. [PMID: 20595010 DOI: 10.1016/j.bbalip.2010.05.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 02/09/2023]
Abstract
Phosphatidylcholine (PC) is an important constituent of the gastrointestinal tract. PC molecules are not only important in intestinal cell membranes but also receiving increasing attention as protective agents in the gastrointestinal barrier. They are largely responsible for establishing the hydrophobic surface of the colon. Decreased phospholipids in colonic mucus could be linked to the pathogenesis of ulcerative colitis, a chronic inflammatory bowel disease. Clinical studies revealed that therapeutic addition of PC to the colonic mucus of these patients alleviated the inflammatory activity. This positive role is still elusive, however, we hypothesized that luminal PC has two possible functions: first, it is essential for surface hydrophobicity, and second, it is integrated into the plasma membrane of enterocytes and it modulates the signaling state of the mucosa. The membrane structure and lipid composition of cells is a regulatory component of the inflammatory signaling pathways. In this perspective, we will shortly summarize what is known about the localization and protective properties of PC in the colonic mucosa before turning to its evident medical importance. We will discuss how PC contributes to our understanding of the pathogenesis of ulcerative colitis and how reinforcing the luminal phospholipid monolayer can be used as a therapeutic concept in humans.
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Affiliation(s)
- Robert Ehehalt
- Department of Gastroenterology, University hospital Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
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8
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Chemistry and Function of Phospholipids. FOOD SCIENCE AND TECHNOLOGY 2010. [DOI: 10.1201/9781420046649.ch2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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Treede I, Braun A, Jeliaskova P, Giese T, Füllekrug J, Griffiths G, Stremmel W, Ehehalt R. TNF-alpha-induced up-regulation of pro-inflammatory cytokines is reduced by phosphatidylcholine in intestinal epithelial cells. BMC Gastroenterol 2009; 9:53. [PMID: 19594939 PMCID: PMC2714528 DOI: 10.1186/1471-230x-9-53] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2008] [Accepted: 07/13/2009] [Indexed: 12/16/2022] Open
Abstract
Background Phosphatidylcholine (PC) is a major lipid of the gastrointestinal mucus layer. We recently showed that mucus from patients suffering from ulcerative colitis has low levels of PC. Clinical studies reveal that the therapeutic addition of PC to the colonic mucus using slow release preparations is beneficial. The positive role of PC in this disease is still unclear; however, we have recently shown that PC has an intrinsic anti-inflammatory property. It could be demonstrated that the exogenous application of PC inhibits membrane-dependent actin assembly and TNF-α-induced nuclear NF-κB activation. We investigate here in more detail the hypothesis that the exogenous application of PC has anti-inflammatory properties. Methods PC species with different fatty acid side chains were applied to differentiated and non-differentiated Caco-2 cells treated with TNF-α to induce a pro-inflammatory response. We analysed TNF-α-induced NF-κB-activation via the transient expression of a NF-κB-luciferase reporter system. Pro-inflammatory gene transcription was detected with the help of a quantitative real time (RT)-PCR analysis. We assessed the binding of TNF-α to its receptor by FACS and analysed lipid rafts by isolating detergent resistant membranes (DRMs). Results The exogenous addition of all PC species tested significantly inhibited TNF-α-induced pro-inflammatory signalling. The expression levels of IL-8, ICAM-1, IP-10, MCP-1, TNF-α and MMP-1 were significantly reduced after PC pre-treatment for at least two hours. The effect was comparable to the inhibition of NF-kB by the NF-kB inhibitor SN 50 and was not due to a reduced binding of TNF-α to its receptor or a decreased surface expression of TNF-α receptors. PC was also effective when applied to the apical side of polarised Caco-2 cultures if cells were stimulated from the basolateral side. PC treatment changed the compartmentation of the TNF-α-receptors 1 and 2 to DRMs. Conclusion PC induces a prolonged inhibition of TNF-α-induced pro-inflammatory signalling. This inhibition may be caused by a shift of the TNF-α receptors at the surface to lipid rafts. Our results may offer a potential molecular explanation for the positive role of PC seen in clinical studies for the treatment of ulcerative colitis.
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Affiliation(s)
- Irina Treede
- Department of Gastroenterology, University of Heidelberg, Heidelberg, Germany.
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Treede I, Braun A, Sparla R, Kühnel M, Giese T, Turner JR, Anes E, Kulaksiz H, Füllekrug J, Stremmel W, Griffiths G, Ehehalt R. Anti-inflammatory effects of phosphatidylcholine. J Biol Chem 2007; 282:27155-27164. [PMID: 17636253 PMCID: PMC2693065 DOI: 10.1074/jbc.m704408200] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We recently showed that mucus from patients with ulcerative colitis, a chronic inflammatory disorder of the colon, is characterized by a low level of phosphatidylcholine (PC) while clinical studies reveal that therapeutic addition of PC using slow release preparations is beneficial. The positive role of PC in this disease is still elusive. Here we tested the hypothesis that exogenous application of PC has anti-inflammatory properties using three model systems. First, human Caco-2 cells were treated with tumor necrosis factor-alpha (TNF-alpha) to induce a pro-inflammatory response via activation of NF-kappaB. Second, latex bead phagosomes were analyzed for their ability to assemble actin in vitro, a process linked to pro-inflammatory signaling and correlating with the growth versus killing of mycobacteria in macrophages. The third system used was the rapid assembly of plasma membrane actin in macrophages in response to sphingosine 1-phosphate. TNF-alpha induced a pro-inflammatory response in Caco-2 cells, including 1) assembly of plasma membrane actin; 2) activation of both MAPKs ERK and p38; 3) transport of NF-kappaB subunits to the nucleus; and 4) subsequent up-regulation of the synthesis of pro-inflammatory gene products. Exogenous addition of most PCs tested significantly inhibited these processes. Other phospholipids like sphingomyelin or phosphatidylethanolamine showed no effects in these assays. PC also inhibited latex bead phagosome actin assembly, the killing of Mycobacterium tuberculosis in macrophages, and the sphingosine 1-phosphate-induced actin assembly in macrophages. TNF-alpha induces the activation of signaling molecules and the reorganization of the actin cytoskeleton in human intestinal cells. Exogenous application of PC blocks pro-inflammatory signaling in Caco-2 cells, in phagosomes in vitro and facilitates intracellular survival of mycobacteria. We provide further evidence that actin assembly by membranes is part of the pro-inflammatory response. Collectively, these results provide a molecular foundation for the clinical studies showing a beneficial effect of PC therapy in ulcerative colitis.
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Affiliation(s)
- Irina Treede
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the; Cell Biology Program, European Molecular Biology Laboratory, Postfach 102209, Heidelberg 69117, Germany, the
| | - Annika Braun
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the
| | - Richard Sparla
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the
| | - Mark Kühnel
- Cell Biology Program, European Molecular Biology Laboratory, Postfach 102209, Heidelberg 69117, Germany, the
| | - Thomas Giese
- Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, Heidelberg 69120, Germany, the
| | - Jerrold R Turner
- Department of Pathology, University of Chicago, MC-1089, 60637 Chicago, Illinois
| | - Elsa Anes
- Unidade dos Retrovirus e Infeccdoas Associades(URIA)-Molecular Pathogenesis Centre, Faculty of Pharmacy, University of Lisbon, av. das Forcas Armadas, Lisbon 1600-083, Portugal, and the
| | - Hasan Kulaksiz
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the
| | - Joachim Füllekrug
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the
| | - Wolfgang Stremmel
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the
| | - Gareth Griffiths
- Cell Biology Program, European Molecular Biology Laboratory, Postfach 102209, Heidelberg 69117, Germany, the
| | - Robert Ehehalt
- Department of Gastroenterology, University Hospital Heidelberg, INF 345, Heidelberg 69120, Germany, the.
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Malmberg NJ, Falke JJ. Use of EPR power saturation to analyze the membrane-docking geometries of peripheral proteins: applications to C2 domains. ACTA ACUST UNITED AC 2005; 34:71-90. [PMID: 15869384 PMCID: PMC3637887 DOI: 10.1146/annurev.biophys.34.040204.144534] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Despite the central importance of peripheral membrane proteins to cellular signaling and metabolic pathways, the structures of protein-membrane interfaces remain largely inaccessible to high-resolution structural methods. In recent years a number of laboratories have contributed to the development of an electron paramagnetic resonance (EPR) power saturation approach that utilizes site-directed spin labeling to determine the key geometric parameters of membrane-docked proteins, including their penetration depths and angular orientations relative to the membrane surface. Representative applications to Ca(2+)-activated, membrane-docking C2 domains are described.
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Olayioye MA, Vehring S, Müller P, Herrmann A, Schiller J, Thiele C, Lindeman GJ, Visvader JE, Pomorski T. StarD10, a START domain protein overexpressed in breast cancer, functions as a phospholipid transfer protein. J Biol Chem 2005; 280:27436-42. [PMID: 15911624 DOI: 10.1074/jbc.m413330200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We originally identified StarD10 as a protein overexpressed in breast cancer that cooperates with the ErbB family of receptor tyrosine kinases in cellular transformation. StarD10 contains a steroidogenic acute regulatory protein (StAR/StarD1)-related lipid transfer (START) domain that is thought to mediate binding of lipids. We now provide evidence that StarD10 interacts with phosphatidylcholine (PC) and phosphatidylethanolamine (PE) by electron spin resonance measurement. Interaction with these phospholipids was verified in a fluorescence resonance energy transfer-based assay with 7-nitro-2,1,3-benzoxadiazol-4-yl-labeled lipids. Binding was not restricted to lipid analogs since StarD10 selectively extracted PC and PE from small unilamellar vesicles prepared with endogenous radiolabeled lipids from Vero monkey kidney cells. Mass spectrometry revealed that StarD10 preferentially selects lipid species containing a palmitoyl or stearoyl chain on the sn-1 and an unsaturated fatty acyl chain (18:1 or 18:2) on the sn-2 position. StarD10 was further shown to bind lipids in vivo by cross-linking of protein expressed in transfected HEK-293T cells with photoactivable phosphatidylcholine. In addition to a lipid binding function, StarD10 transferred PC and PE between membranes. Interestingly, these lipid binding and transfer specificities distinguish StarD10 from the related START domain proteins Pctp and CERT, suggesting a distinct biological function.
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Affiliation(s)
- Monilola A Olayioye
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria 3050, Australia
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Fernandez-Fuentes N, Hermoso A, Espadaler J, Querol E, Aviles FX, Oliva B. Classification of common functional loops of kinase super-families. Proteins 2004; 56:539-55. [PMID: 15229886 DOI: 10.1002/prot.20136] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A structural classification of loops has been obtained from a set of 141 protein structures classified as kinases. A total of 1813 loops was classified into 133 subclasses (9 betabeta(links), 15 betabeta(hairpins), 31 alpha-alpha, 46 alpha-beta and 32 beta-alpha). Functional information and specific features relating subclasses and function were included in the classification. Functional loops such as the P-loop (shared by different folds) or the Gly-rich-loop, among others, were classified into structural motifs. As a result, a common mechanism of catalysis and substrate binding was proved for most kinases. Additionally, the multiple-alignment of loop sequences made within each subclass was shown to be useful for comparative modeling of kinase loops. The classification is summarized in a kinase loop database located at http://sbi.imim.es/archki.
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Affiliation(s)
- Narcis Fernandez-Fuentes
- Institut de Biotecnologia i Biomedicina and Department de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
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Cascio M. Connexins and their environment: effects of lipids composition on ion channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1711:142-53. [PMID: 15955299 DOI: 10.1016/j.bbamem.2004.12.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 11/25/2004] [Accepted: 12/02/2004] [Indexed: 11/16/2022]
Abstract
Intercellular communication is mediated through paired connexons that form an aqueous pore between two adjacent cells. These membrane proteins reside in the plasma membrane of their respective cells and their activity is modulated by the composition of the lipid bilayer. The effects of the bilayer on connexon structure and function may be direct or indirect, and may arise from specific binding events or the physicochemical properties of the bilayer. While the effects of the bilayer and its constituent lipids on gap junction activity have been described in the literature, the underlying mechanisms of the interaction of connexin with its lipidic microenvironment are not as well characterized. Given that the information regarding connexons is limited, in this review, the specific roles of lipids and the properties of the bilayer on membrane protein structure and function are described for other ion channels as well as for connexons.
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Affiliation(s)
- Michael Cascio
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, United States.
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15
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Davis AJ, Perera IY, Boss WF. Cyclodextrins enhance recombinant phosphatidylinositol phosphate kinase activity. J Lipid Res 2004; 45:1783-9. [PMID: 15210840 DOI: 10.1194/jlr.d400005-jlr200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inositol lipid kinases have been studied extensively in both plant and animal systems. However, major limitations for in vitro studies of recombinant lipid kinases are the low specific activity and instability of the purified proteins. Our goal was to determine if cyclodextrins would provide an effective substrate delivery system and enhance the specific activity of lipid kinases. For these studies, we have used recombinant Arabidopsis thaliana phosphatidylinositol phosphate kinase 1 (At PIPK1). At PIPK1 was produced as a fusion protein with glutathione-S-transferase and purified on glutathione-Sepharose beads. A comparison of lipid kinase activity using substrate prepared in alpha-, beta-, or gamma-cyclodextrin indicated that beta-cyclodextrin was most effective and enhanced lipid kinase activity 6-fold compared with substrate prepared in Triton X-100-mixed micelles. We have optimized reaction conditions and shown that product can be recovered from the cyclodextrin-treated recombinant protein, which reveals a potential method for automating the assay for pharmacological screening.
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Affiliation(s)
- Amanda J Davis
- Department of Botany, North Carolina State University, Raleigh, NC 27695, USA
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16
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Sterin M, Cohen JS, Ringel I. Hormone Sensitivity is Reflected in the Phospholipid Profiles of Breast Cancer Cell Lines. Breast Cancer Res Treat 2004; 87:1-11. [PMID: 15377845 DOI: 10.1023/b:brea.0000041572.07837.ec] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have found that the profiles of total phospholipids in malignant breast cancer cell lines change going from hormone sensitive to highly hormone resistant cells lines. In particular, two phospholipid components that were absent or at very low levels in hormone sensitive MCF7 cells and moderately hormone sensitive cell lines (MIII, LCC2) were found in relatively high proportions in highly hormone resistant cell lines (MB435, MB231). These two components were shown to be the alkylacylphosphatidylcholine (AAPtdC) and the unsaturated analog plasmenylphosphatidylethanolamine (plasmenyl-PtdE). Another component phosphatidylethanolamine (PtdE) increased in correlation with the degree of hormone insensitivity. This was shown using 31P NMR spectroscopy of lipid extracts of the cells, and was confirmed using HPLC analysis, as well as other techniques. The significance of these results for the metabolic characteristics of these cell lines is related to the therapeutic responsiveness of breast cancer.
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Affiliation(s)
- Marina Sterin
- Department of Pharmacology, Faculty of Medicine, The Hebrew University, Jerusalem, Israel
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17
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Malmberg NJ, Van Buskirk DR, Falke JJ. Membrane-docking loops of the cPLA2 C2 domain: detailed structural analysis of the protein-membrane interface via site-directed spin-labeling. Biochemistry 2004; 42:13227-40. [PMID: 14609334 PMCID: PMC3637888 DOI: 10.1021/bi035119+] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
C2 domains are protein modules found in numerous eukaryotic signaling proteins, where their function is to target the protein to cell membranes in response to a Ca(2+) signal. Currently, the structure of the interface formed between the protein and the phospholipid bilayer is inaccessible to high-resolution structure determination, but EPR site-directed spin-labeling can provide a detailed medium-resolution view of this interface. To apply this approach to the C2 domain of cytosolic phospholipase A(2) (cPLA(2)), single cysteines were introduced at all 27 positions in the three Ca(2+)-binding loops and labeled with a methanethiosulfonate spin-label. Altogether, 24 of the 27 spin-labeled domains retained Ca(2+)-activated phospholipid binding. EPR spectra of these 24 labeled domains obtained in the presence and absence of Ca(2+) indicate that Ca(2+) binding triggers subtle changes in the dynamics of two localized regions within the Ca(2+)-binding loops: one face of the loop 1 helix and the junction between loops 1 and 2. However, no significant changes in loop structure were detected upon Ca(2+) binding, nor upon Ca(2+)-triggered docking to membranes. EPR depth parameters measured in the membrane-docked state allow determination of the penetration depth of each residue with respect to the membrane surface. Analysis of these depth parameters, using an improved, generalizable geometric approach, provides the most accurate picture of penetration depth and angular orientation currently available for a membrane-docked peripheral protein. Finally, the observation that Ca(2+) binding does not trigger large rearrangements of the membrane-docking loops favors the electrostatic switch model for Ca(2+) activation and disfavors, or places strong constraints on, the conformational switch model.
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Affiliation(s)
| | | | - Joseph J. Falke
- To whom correspondence should be addressed. . Tel: (303) 492-3503
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18
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Abstract
Dihedral angles are evaluated for the phospholipid ligands of the lipid-binding proteins found in the Protein Data Base (PDB). Phospholipid structures occur with a trans C1-C2 configuration of the glycerol backbone and oppositely extended chains, in addition to the gauche C1-C2 rotamers found in membranes. Headgroup conformations are not restricted to the single bent-down configuration and gauche-gauche configuration of the phosphodiester that is found in phospholipid crystals. Additionally, fully extended headgroups and orientations directed away from the lipid chains are found for phospholipids in the protein binding pockets. On average, the hydrocarbon chains of the protein-bound lipids are conformationally more disordered than in fluid bilayer membranes. However, much of this configurational disorder arises from energetically disallowed skew conformations. This suggests a configurational heterogeneity in the lipids at a single binding site: Eclipsed conformations occur also in some lipid headgroups and glycerol backbones. Stereochemical violations appear for some of the ester carboxyl groups of the protein-bound phospholipids in the PDB, and two glycerol backbones have the incorrect enantiomeric configuration.
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Affiliation(s)
- Derek Marsh
- Max-Planck-Institut für biophysikalische Chemie, 37070 Göttingen, Germany.
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19
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20
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Stahelin RV, Rafter JD, Das S, Cho W. The molecular basis of differential subcellular localization of C2 domains of protein kinase C-alpha and group IVa cytosolic phospholipase A2. J Biol Chem 2003; 278:12452-60. [PMID: 12531893 DOI: 10.1074/jbc.m212864200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The C2 domain is a Ca(2+)-dependent membrane-targeting module found in many cellular proteins involved in signal transduction or membrane trafficking. C2 domains are unique among membrane targeting domains in that they show a wide range of lipid selectivity for the major components of cell membranes, including phosphatidylserine and phosphatidylcholine. To understand how C2 domains show diverse lipid selectivity and how this functional diversity affects their subcellular targeting behaviors, we measured the binding of the C2 domains of group IVa cytosolic phospholipase A(2) (cPLA(2)) and protein kinase C-alpha (PKC-alpha) to vesicles that model cell membranes they are targeted to, and we monitored their subcellular targeting in living cells. The surface plasmon resonance analysis indicates that the PKC-alpha C2 domain strongly prefers the cytoplasmic plasma membrane mimic to the nuclear membrane mimic due to high phosphatidylserine content in the former and that Asn(189) plays a key role in this specificity. In contrast, the cPLA(2) C2 domain has specificity for the nuclear membrane mimic over the cytoplasmic plasma membrane mimic due to high phosphatidylcholine content in the former and aromatic and hydrophobic residues in the calcium binding loops of the cPLA(2) C2 domain are important for its lipid specificity. The subcellular localization of enhanced green fluorescent protein-tagged C2 domains and mutants transfected into HEK293 cells showed that the subcellular localization of the C2 domains is consistent with their lipid specificity and could be tailored by altering their in vitro lipid specificity. The relative cell membrane translocation rate of selected C2 domains was also consistent with their relative affinity for model membranes. Together, these results suggest that biophysical principles that govern the in vitro membrane binding of C2 domains can account for most of their subcellular targeting properties.
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Affiliation(s)
- Robert V Stahelin
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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21
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Abstract
A recent publication by Cravatt and colleagues which describes the structure of an integral membrane protein (FAAH) highlights that the structural differences between membrane proteins and soluble proteins are not as disparate as is sometimes believed.
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Affiliation(s)
- James H Hurley
- 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 20890, USA
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22
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Allen-Baume V, Ségui B, Cockcroft S. Current thoughts on the phosphatidylinositol transfer protein family. FEBS Lett 2002; 531:74-80. [PMID: 12401207 DOI: 10.1016/s0014-5793(02)03412-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Monomeric transport of lipids is carried out by a class of proteins that can shield a lipid from the aqueous environment by binding the lipid in a hydrophobic cavity. One such group of proteins is the phosphatidylinositol transfer proteins (PITP) that can bind phosphatidylinositol and phosphatidylcholine and transfer them from one membrane compartment to another. PITPs are found in both unicellular and multicellular organisms but not bacteria. In mice and humans, the PITP domain responsible for lipid transfer is found in five proteins, which can be classified into two classes based on sequence. Class I PITPs comprises two family members, alpha and beta, small 35 kDa proteins with a single PITP domain which are ubiquitously expressed. Class IIA PITPs (RdgBalphaI and II) are larger proteins possessing additional domains that target the protein to membranes and are only able to bind lipids but not mediate transfer. Finally, Class IIB PITP (RdgBbeta) is similar to Class I in size (38 kDa) and is also ubiquitously expressed. Class III PITPs, exemplified by the Sec14p family, are found in yeast and plants but are unrelated in sequence and structure to Class I and Class II PITPs. In this review we discuss whether PITP proteins are passive transporters or are regulated proteins that are able to couple their transport and binding properties to specific biological functions including inositol lipid signalling and membrane turnover.
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23
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Kunz J, Fuelling A, Kolbe L, Anderson RA. Stereo-specific substrate recognition by phosphatidylinositol phosphate kinases is swapped by changing a single amino acid residue. J Biol Chem 2002; 277:5611-9. [PMID: 11733501 DOI: 10.1074/jbc.m110775200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type I and type II phosphatidylinositol phosphate (PIP) kinases generate the lipid second messenger phosphatidylinositol (PtdIns) 4,5-bisphosphate and thus play fundamental roles in the regulation of many cellular processes. Although the two kinase families are highly homologous, they phosphorylate distinct substrates and are functionally non-redundant. Type I PIP kinases phosphorylate PtdIns 4-phosphate at the D-5 hydroxyl group and are consequently PtdIns 4-phosphate 5-kinases. By contrast, type II PIP kinases are PtdIns 5-phosphate 4-kinases that phosphorylate PtdIns 5-phosphate at the D-4 position. Type I PIP kinases, in addition, also phosphorylate other phosphoinositides in vitro and in vivo and thus have the potential to generate multiple lipid second messengers. To understand how these enzymes differentiate between stereoisomeric substrates, we used a site-directed mutagenesis approach. We show that a single amino acid substitution in the activation loop, A381E in IIbeta and the corresponding mutation E362A in Ibeta, is sufficient to swap substrate specificity between these PIP kinases. In addition to its role in substrate specificity, the type I activation loop is also key in subcellular targeting. The Ibeta(E362A) mutant and other mutants with reduced PtdIns 4-phosphate binding affinity were largely cytosolic when expressed in mammalian cells in contrast to wild-type Ibeta which targets to the plasma membrane. These results clearly establish the role of the activation loop in determining both signaling specificity and plasma membrane targeting of type I PIP kinases.
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Affiliation(s)
- Jeannette Kunz
- Department of Pharmacology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA
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24
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Snyder JT, Rossman KL, Baumeister MA, Pruitt WM, Siderovski DP, Der CJ, Lemmon MA, Sondek J. Quantitative analysis of the effect of phosphoinositide interactions on the function of Dbl family proteins. J Biol Chem 2001; 276:45868-75. [PMID: 11577097 DOI: 10.1074/jbc.m106731200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Normally, Rho GTPases are activated by the removal of bound GDP and the concomitant loading of GTP catalyzed by members of the Dbl family of guanine nucleotide exchange factors (GEFs). This family of GEFs invariantly contain a Dbl homology (DH) domain adjacent to a pleckstrin homology (PH) domain, and while the DH domain usually is sufficient to catalyze nucleotide exchange, possible roles for the conserved PH domain remain ambiguous. Here we demonstrate that the conserved PH domains of three distinct Dbl family proteins, intersectin, Dbs, and Tiam1, selectively bind lipid vesicles only when phosphoinositides are present. While the PH domains of intersectin and Dbs promiscuously bind several multiphosphorylated phosphoinositides, Tiam1 selectively interacts with phosphatidylinositol 3-phosphate (K(D) approximately 5-10 microm). In addition, and in contrast to recent reports, catalysis of nucleotide exchange on nonprenylated Rac1 provided by various extended portions of Tiam1 is not influenced by (a) soluble phosphoinositide head groups, (b) dibutyl versions of phosphoinositides, or (c) lipid vesicles containing phosphoinositides. Likewise, GEF activity afforded by DH/PH fragments of intersectin and Dbs are also not altered by phosphoinositide interactions. These results strongly suggest that unless all relevant components are localized to a lipid membrane surface, Dbl family GEFs generally are not intrinsically modulated by binding phosphoinositides.
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Affiliation(s)
- J T Snyder
- Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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25
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Tsujishita Y, Guo S, Stolz LE, York JD, Hurley JH. Specificity Determinants in Phosphoinositide Dephosphorylation. Cell 2001; 105:379-89. [PMID: 11348594 DOI: 10.1016/s0092-8674(01)00326-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Inositol polyphosphate 5-phosphatases are central to intracellular processes ranging from membrane trafficking to Ca(2+) signaling, and defects in this activity result in the human disease Lowe syndrome. The 1.8 resolution structure of the inositol polyphosphate 5-phosphatase domain of SPsynaptojanin bound to Ca(2+) and inositol (1,4)-bisphosphate reveals a fold and an active site His and Asp pair resembling those of several Mg(2+)-dependent nucleases. Additional loops mediate specific inositol polyphosphate contacts. The 4-phosphate of inositol (1,4)-bisphosphate is misoriented by 4.6 compared to the reactive geometry observed in the apurinic/apyrimidinic endonuclease 1, explaining the dephosphorylation site selectivity of the 5-phosphatases. Based on the structure, a series of mutants are described that exhibit altered substrate specificity providing general determinants for substrate recognition.
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Affiliation(s)
- Y Tsujishita
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, , Bethesda, MD 20892, USA
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