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Nachliel E, Gutman M. Reaction within the coulomb-cage; science in retrospect. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184071. [PMID: 36244436 DOI: 10.1016/j.bbamem.2022.184071] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 08/01/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022]
Abstract
The Coulomb-cage is defined as the space where the electrostatic interaction between two bodies is more intensive than the thermal energy (kBT). For small molecule, the Coulomb-cage is a small sphere, extending only few water molecules towards the bulk and its radius is sensitive to the ionic strength of the solution. For charged proteins or membranal structures, the Coulomb-cage can engulf large fraction of the surface and provides a preferred pathway for ion propagation along the surface. Similarly, electrostatic potential at the inner space of a channel can form preferential trajectories passage for ions. The dynamics of ions inside the Coulomb-cage of ions was formulated by the studies of proton-anion recombination of excited photoacids. In the present article, we recount the study of intra- Coulomb-cage reaction taking place on the surface of macro-molecular bodies like micelles, membranes, proteins and intra-protein cavities. The study progressed stepwise, tracing the dynamics of a proton ejected from a photo-acid molecule located at defined sites (on membrane, inter-membrane space, active site of enzyme, inside Large Pore Channels etc.). Accumulation of experimental observations encouraged us to study of the reaction mechanism by molecular dynamics simulations of ions within the Coulomb-cage of proteins surface or inside large pores. The intra-Coulomb-cage proton transfer events follows closely the fine structure of the electrostatic field inside the cage and reflects the shape of nearby dielectric boundaries, the temporal ordering of the solvent molecules and the structural fluctuations of the charged side chains. The article sums some 40 years of research, which in retrospect clarifies the intra-Coulomb-cage reaction mechanism.
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Affiliation(s)
- E Nachliel
- Laser Laboratory for Fast Reactions, Dep. Of Biochemistry and Molecular Biology, Life Sciences, Tel Aviv University, Israel
| | - M Gutman
- Laser Laboratory for Fast Reactions, Dep. Of Biochemistry and Molecular Biology, Life Sciences, Tel Aviv University, Israel.
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2
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Brown AI, Koslover EF. Design principles for the glycoprotein quality control pathway. PLoS Comput Biol 2021; 17:e1008654. [PMID: 33524026 PMCID: PMC7877790 DOI: 10.1371/journal.pcbi.1008654] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 02/11/2021] [Accepted: 12/21/2020] [Indexed: 01/11/2023] Open
Abstract
Newly-translated glycoproteins in the endoplasmic reticulum (ER) often undergo cycles of chaperone binding and release in order to assist in folding. Quality control is required to distinguish between proteins that have completed native folding, those that have yet to fold, and those that have misfolded. Using quantitative modeling, we explore how the design of the quality-control pathway modulates its efficiency. Our results show that an energy-consuming cyclic quality-control process, similar to the observed physiological system, outperforms alternative designs. The kinetic parameters that optimize the performance of this system drastically change with protein production levels, while remaining relatively insensitive to the protein folding rate. Adjusting only the degradation rate, while fixing other parameters, allows the pathway to adapt across a range of protein production levels, aligning with in vivo measurements that implicate the release of degradation-associated enzymes as a rapid-response system for perturbations in protein homeostasis. The quantitative models developed here elucidate design principles for effective glycoprotein quality control in the ER, improving our mechanistic understanding of a system crucial to maintaining cellular health. We explore the architecture and limitations of the quality-control pathway responsible for efficient folding of secretory proteins. Newly-synthesized proteins are tagged by the attachment of a ‘glycan’ sugar chain which facilitates their binding to a chaperone that assists protein folding. Removal of a specific sugar group on the glycan ends the interaction with the chaperone, and not-yet-folded proteins can be re-tagged for another round of chaperone binding. A degradation pathway acts in parallel with the folding cycle, to remove those proteins that have remained unfolded for a sufficiently long time. We develop and solve a mathematical model of this quality-control system, showing that the cyclical design found in living cells is uniquely able to maximize folded protein throughput while avoiding accumulation of unfolded proteins. Although this physiological model provides the best performance, its parameters must be adjusted to perform optimally under different protein production loads, and any single fixed set of parameters leads to poor performance when production rate is altered. We find that a single adjustable parameter, the protein degradation rate, is sufficient to allow optimal performance across a range of conditions. Interestingly, observations of living cells suggest that the degradation speed is indeed rapidly adjusted.
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Affiliation(s)
- Aidan I. Brown
- Department of Physics, University of California, San Diego, San Diego, California, United States of America
| | - Elena F. Koslover
- Department of Physics, University of California, San Diego, San Diego, California, United States of America
- * E-mail:
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Lamriben L, Graham JB, Adams BM, Hebert DN. N-Glycan-based ER Molecular Chaperone and Protein Quality Control System: The Calnexin Binding Cycle. Traffic 2016; 17:308-26. [PMID: 26676362 DOI: 10.1111/tra.12358] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 12/14/2015] [Accepted: 12/14/2015] [Indexed: 12/17/2022]
Abstract
Helenius and colleagues proposed over 20-years ago a paradigm-shifting model for how chaperone binding in the endoplasmic reticulum was mediated and controlled for a new type of molecular chaperone- the carbohydrate-binding chaperones, calnexin and calreticulin. While the originally established basics for this lectin chaperone binding cycle holds true today, there has been a number of important advances that have expanded our understanding of its mechanisms of action, role in protein homeostasis, and its connection to disease states that are highlighted in this review.
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Affiliation(s)
- Lydia Lamriben
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Jill B Graham
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Benjamin M Adams
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
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Caramelo JJ, Parodi AJ. A sweet code for glycoprotein folding. FEBS Lett 2015; 589:3379-87. [PMID: 26226420 DOI: 10.1016/j.febslet.2015.07.021] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 07/15/2015] [Accepted: 07/15/2015] [Indexed: 12/11/2022]
Abstract
Glycoprotein synthesis is initiated in the endoplasmic reticulum (ER) lumen upon transfer of a glycan (Glc3Man9GlcNAc2) from a lipid derivative to Asn residues (N-glycosylation). N-Glycan-dependent quality control of glycoprotein folding in the ER prevents exit to Golgi of folding intermediates, irreparably misfolded glycoproteins and incompletely assembled multimeric complexes. It also enhances folding efficiency by preventing aggregation and facilitating formation of proper disulfide bonds. The control mechanism essentially involves four components, resident lectin-chaperones (calnexin and calreticulin) that recognize monoglucosylated polymannose protein-linked glycans, lectin-associated oxidoreductase acting on monoglucosylated glycoproteins (ERp57), a glucosyltransferase that creates monoglucosylated epitopes in protein-linked glycans (UGGT) and a glucosidase (GII) that removes the glucose units added by UGGT. This last enzyme is the only mechanism component sensing glycoprotein conformations as it creates monoglucosylated glycans exclusively in not properly folded glycoproteins or in not completely assembled multimeric glycoprotein complexes. Glycoproteins that fail to properly fold are eventually driven to proteasomal degradation in the cytosol following the ER-associated degradation pathway, in which the extent of N-glycan demannosylation by ER mannosidases play a relevant role in the identification of irreparably misfolded glycoproteins.
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Affiliation(s)
- Julio J Caramelo
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Avda. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina.
| | - Armando J Parodi
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Avda. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina.
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“Three sources and three component parts” of free oligosaccharides. UKRAINIAN BIOCHEMICAL JOURNAL 2014; 86:5-17. [DOI: 10.15407/ubj86.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Aikawa JI, Takeda Y, Matsuo I, Ito Y. Trimming of glucosylated N-glycans by human ER α1,2-mannosidase I. ACTA ACUST UNITED AC 2014; 155:375-84. [DOI: 10.1093/jb/mvu008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Deciphering the roles of glycan processing in glycoprotein quality control through organic synthesis. Biosci Biotechnol Biochem 2013; 77:2331-8. [PMID: 24317068 DOI: 10.1271/bbb.130594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Protein quality control (QC) in the endoplasmic reticulum (ER) comprises many aspects, including folding and transport of nascent proteins and degradation of misfolded proteins. Recent studies have revealed that high-mannose-type glycans play pivotal roles in the QC process. To gain knowledge of the molecular basis of this process with well-defined homogeneous compounds, we achieved a convergent synthesis of high-mannose-type glycans and their functionalized derivatives. A major part of our study focused on analyses of UDP-Glc: glycoprotein glucosyltransferase (UGGT) and ER glucosidase II, which play crucial roles in glycoprotein QC, to clarify their specificities. In addition, we established an in vitro assay system mimicking the in vivo condition, which is highly crowded due to the presence of various macromolecules.
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Brandi J, Dando I, Palmieri M, Donadelli M, Cecconi D. Comparative proteomic and phosphoproteomic profiling of pancreatic adenocarcinoma cells treated with CB1 or CB2 agonists. Electrophoresis 2013; 34:1359-68. [PMID: 23463621 DOI: 10.1002/elps.201200402] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 02/07/2013] [Accepted: 02/08/2013] [Indexed: 01/06/2023]
Abstract
The pancreatic adenocarcinoma cell line Panc1 was treated with cannabinoid receptor ligands (arachidonylcyclopropylamide or GW405833) in order to elucidate the molecular mechanism of their anticancer effect. A proteomic approach was used to analyze the protein and phosphoprotein profiles. Western blot and functional data mining were also employed in order to validate results, classify proteins, and explore their potential relationships. We demonstrated that the two cannabinoids act through a widely common mechanism involving up- and down-regulation of proteins related to energetic metabolism and cell growth regulation. Overall, the results reported might contribute to the development of a therapy based on cannabinoids for pancreatic adenocarcinoma.
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Affiliation(s)
- Jessica Brandi
- Proteomics and Mass Spectrometry Laboratory, Department of Biotechnology, University of Verona, Verona, Italy
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Ito Y, Takeda Y. Analysis of glycoprotein processing in the endoplasmic reticulum using synthetic oligosaccharides. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2012; 88:31-40. [PMID: 22314014 PMCID: PMC3316936 DOI: 10.2183/pjab.88.31] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/19/2011] [Indexed: 05/31/2023]
Abstract
Protein quality control (QC) in the endoplasmic reticulum (ER) comprises many steps, including folding and transport of nascent proteins as well as degradation of misfolded proteins. Recent studies have revealed that high-mannose-type glycans play a pivotal role in the QC process. To gain knowledge about the molecular basis of this process with well-defined homogeneous compounds, we achieved a convergent synthesis of high-mannose-type glycans and their functionalized derivatives. We focused on analyses of UDP-Glc: glycoprotein glucosyltransferase (UGGT) and ER Glucosidase II, which play crucial roles in glycoprotein QC; however, their specificities remain unclear. In addition, we established an in vitro assay system mimicking the in vivo condition which is highly crowded because of the presence of various biomacromolecules.
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Bosis E, Salomon D, Sessa G. A simple yeast-based strategy to identify host cellular processes targeted by bacterial effector proteins. PLoS One 2011; 6:e27698. [PMID: 22110728 PMCID: PMC3216995 DOI: 10.1371/journal.pone.0027698] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 10/23/2011] [Indexed: 12/19/2022] Open
Abstract
Bacterial effector proteins, which are delivered into the host cell via the type III secretion system, play a key role in the pathogenicity of Gram-negative bacteria by modulating various host cellular processes to the benefit of the pathogen. To identify cellular processes targeted by bacterial effectors, we developed a simple strategy that uses an array of yeast deletion strains fitted into a single 96-well plate. The array is unique in that it was optimized computationally such that despite the small number of deletion strains, it covers the majority of genes in the yeast synthetic lethal interaction network. The deletion strains in the array are screened for hypersensitivity to the expression of a bacterial effector of interest. The hypersensitive deletion strains are then analyzed for their synthetic lethal interactions to identify potential targets of the bacterial effector. We describe the identification, using this approach, of a cellular process targeted by the Xanthomonas campestris type III effector XopE2. Interestingly, we discover that XopE2 affects the yeast cell wall and the endoplasmic reticulum stress response. More generally, the use of a single 96-well plate makes the screening process accessible to any laboratory and facilitates the analysis of a large number of bacterial effectors in a short period of time. It therefore provides a promising platform for studying the functions and cellular targets of bacterial effectors and other virulence proteins.
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Affiliation(s)
- Eran Bosis
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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Amin MN, Huang W, Mizanur RM, Wang LX. Convergent synthesis of homogeneous Glc1Man9GlcNAc2-protein and derivatives as ligands of molecular chaperones in protein quality control. J Am Chem Soc 2011; 133:14404-17. [PMID: 21819116 DOI: 10.1021/ja204831z] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A detailed understanding of the molecular mechanism of chaperone-assisted protein quality control is often hampered by the lack of well-defined homogeneous glycoprotein probes. We describe here a highly convergent chemoenzymatic synthesis of the monoglucosylated glycoforms of bovine ribonuclease (RNase) as specific ligands of lectin-like chaperones calnexin (CNX) and calreticulin (CRT) that are known to recognize the monoglucosylated high-mannose oligosaccharide component of glycoproteins in protein folding. The synthesis of a selectively modified glycoform Gal(1)Glc(1)Man(9)GlcNAc(2)-RNase was accomplished by chemical synthesis of a large N-glycan oxazoline and its subsequent enzymatic ligation to GlcNAc-RNase under the catalysis of a glycosynthase. Selective removal of the terminal galactose by a β-galactosidase gave the Glc(1)Man(9)GlcNAc(2)-RNase glycoform in excellent yield. CD spectroscopic analysis and RNA-hydrolyzing assay indicated that the synthetic RNase glycoforms maintained essentially the same global conformations and were fully active as the natural bovine ribonuclease B. SPR binding studies revealed that the Glc(1)Man(9)GlcNAc(2)-RNase had high affinity to lectin CRT, while the synthetic Man(9)GlcNAc(2)-RNase glycoform and natural RNase B did not show CRT-binding activity. These results confirmed the essential role of the glucose moiety in the chaperone molecular recognition. Interestingly, the galactose-masked glycoform Gal(1)Glc(1)Man(9)GlcNAc(2)-RNase also showed significant affinity to lectin CRT, suggesting that a galactose β-1,4-linked to the key glucose moiety does not significantly block the lectin binding. These synthetic homogeneous glycoprotein probes should be valuable for a detailed mechanistic study on how molecular chaperones work in concert to distinguish between misfolded and folded glycoproteins in the protein quality control cycle.
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Affiliation(s)
- Mohammed N Amin
- Institute of Human Virology, Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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Protein Quality Control, Retention, and Degradation at the Endoplasmic Reticulum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:197-280. [DOI: 10.1016/b978-0-12-386033-0.00005-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Takeda Y, Totani K, Matsuo I, Ito Y. The action of bromoconduritol on ER glucosidase II. Bioorg Med Chem Lett 2010; 20:5357-9. [DOI: 10.1016/j.bmcl.2009.05.125] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/29/2009] [Accepted: 05/30/2009] [Indexed: 11/26/2022]
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D'Alessio C, Caramelo JJ, Parodi AJ. UDP-GlC:glycoprotein glucosyltransferase-glucosidase II, the ying-yang of the ER quality control. Semin Cell Dev Biol 2010; 21:491-9. [PMID: 20045480 DOI: 10.1016/j.semcdb.2009.12.014] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 12/22/2022]
Abstract
The N-glycan-dependent quality control of glycoprotein folding prevents endoplasmic to Golgi exit of folding intermediates, irreparably misfolded glycoproteins and incompletely assembled multimeric complexes. It also enhances folding efficiency by preventing aggregation and facilitating formation of proper disulfide bonds. The control mechanism essentially involves four components, resident lectin-chaperones that recognize monoglucosylated polymannose glycans, a lectin-associated oxidoreductase acting on monoglucosylated glycoproteins, a glucosyltransferase that creates monoglucosytlated epitopes in protein-linked glycans and a glucosidase that removes the glucose units added by the glucosyltransferase. This last enzyme is the only mechanism component sensing glycoprotein conformations as it creates monoglucosylated glycans exclusively in not properly folded species or in not completely assembled complexes. The glucosidase is a dimeric heterodimer composed of a catalytic subunit and an additional one that is partially responsible for the ER localization of the enzyme and for the enhancement of the deglucosylation rate as its mannose 6-phosphate receptor homologous domain presents the substrate to the catalytic site. This review deals with our present knowledge on the glucosyltransferase and the glucosidase.
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Affiliation(s)
- Cecilia D'Alessio
- Laboratory of Glycobiology, Fundación Instituto Leloir, Avda. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
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Ishiwata A, Lee YJ, Ito Y. Recent advances in stereoselective glycosylation through intramolecular aglycon delivery. Org Biomol Chem 2010; 8:3596-608. [DOI: 10.1039/c004281a] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Takeda Y, Totani K, Matsuo I, Ito Y. Chemical approaches toward understanding glycan-mediated protein quality control. Curr Opin Chem Biol 2009; 13:582-91. [DOI: 10.1016/j.cbpa.2009.09.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 09/01/2009] [Accepted: 09/05/2009] [Indexed: 10/20/2022]
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Evaluation of the heterogeneous reactivity of the syntaxin molecules on the inner leaflet of the plasma membrane. J Neurosci 2009; 29:12292-301. [PMID: 19793988 DOI: 10.1523/jneurosci.0710-09.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The soluble N-ethylmaleimide-sensitive fusion (NSF) attachment protein (SNAP) receptor (SNARE) protein syntaxin 1A forms nano-sized clusters (membrane rafts) on the plasma membrane (PM) that are in equilibrium with freely diffusing syntaxin molecules. SNARE-complex formation between syntaxin 1A and SNAP-25 (synaptosome-associated protein of 25 kDa) on the PM and synaptobrevin 2 on the vesicles (trans-SNAREs) is crucial for vesicle priming and fusion. This process might be impeded by the spontaneous accumulation of non-fusogenic cis-SNARE complexes formed when all three SNARE proteins reside on the PM. We investigated the kinetics of cis-SNARE complex assembly and disassembly and both exhibited biphasic behavior. The experimental measurements were analyzed through integration of differential rate equations pertinent to the reaction mechanism and through the application of a heuristic search for time constants and concentrations using a genetic algorithm. Reconstruction of the measurements necessitated the partitioning of syntaxin into two phases that might represent the syntaxin clusters and free syntaxin outside the clusters. The analysis suggests that most of the syntaxin in the clusters is concentrated in a nonreactive form. Consequently, cis-SNARE complex assembly in the clusters is substantially slower than outside the rafts. Interestingly, the clusters also mediate efficient disassembly of cis-SNARE complexes possibly attributable to the high local concentration of complexes in the clusters area that allows efficient disassembly by the enzymatic reaction of NSF.
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Sol ERM, Hovsepyan M, Bergsten P. Proteins altered by elevated levels of palmitate or glucose implicated in impaired glucose-stimulated insulin secretion. Proteome Sci 2009; 7:24. [PMID: 19607692 PMCID: PMC2732594 DOI: 10.1186/1477-5956-7-24] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Accepted: 07/16/2009] [Indexed: 01/09/2023] Open
Abstract
Background Development of type 2 diabetes mellitus (T2DM) is characterized by aberrant insulin secretory patterns, where elevated insulin levels at non-stimulatory basal conditions and reduced hormonal levels at stimulatory conditions are major components. To delineate mechanisms responsible for these alterations we cultured INS-1E cells for 48 hours at 20 mM glucose in absence or presence of 0.5 mM palmitate, when stimulatory secretion of insulin was reduced or basal secretion was elevated, respectively. Results After culture, cells were protein profiled by SELDI-TOF-MS and 2D-PAGE. Differentially expressed proteins were discovered and identified by peptide mass fingerprinting. Complimentary protein profiles were obtained by the two approaches with SELDI-TOF-MS being more efficient in separating proteins in the low molecular range and 2D-PAGE in the high molecular range. Identified proteins included alpha glucosidase, calmodulin, gars, glucose-6-phosphate dehydrogenase, heterogenous nuclear ribonucleoprotein A3, lon peptidase, nicotineamide adenine dinucleotide hydrogen (NADH) dehydrogenase, phosphoglycerate kinase, proteasome p45, rab2, pyruvate kinase and t-complex protein. The observed glucose-induced differential protein expression pattern indicates enhanced glucose metabolism, defense against reactive oxygen species, enhanced protein translation, folding and degradation and decreased insulin granular formation and trafficking. Palmitate-induced changes could be related to altered exocytosis. Conclusion The identified altered proteins indicate mechanism important for altered β-cell function in T2DM.
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Affiliation(s)
- E-ri M Sol
- Department of Medical Cell Biology, Uppsala University, Sweden.
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