1
|
Ferreras S, Singh NP, Le Borgne R, Bun P, Binz T, Parton RG, Verbavatz JM, Vannier C, Galli T. A synthetic organelle approach to probe SNARE-mediated membrane fusion in a bacterial host. J Biol Chem 2023; 299:102974. [PMID: 36738791 PMCID: PMC10011478 DOI: 10.1016/j.jbc.2023.102974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
In vivo and in vitro assays, particularly reconstitution using artificial membranes, have established the role of synaptic soluble N-Ethylmaleimide-sensitive attachment protein receptors (SNAREs) VAMP2, Syntaxin-1A, and SNAP-25 in membrane fusion. However, using artificial membranes requires challenging protein purifications that could be avoided in a cell-based assay. Here, we developed a synthetic biological approach based on the generation of membrane cisternae by the integral membrane protein Caveolin in Escherichia coli and coexpression of SNAREs. Syntaxin-1A/SNAP-25/VAMP-2 complexes were formed and regulated by SNARE partner protein Munc-18a in the presence of Caveolin. Additionally, Syntaxin-1A/SNAP-25/VAMP-2 synthesis provoked increased length of E. coli only in the presence of Caveolin. We found that cell elongation required SNAP-25 and was inhibited by tetanus neurotoxin. This elongation was not a result of cell division arrest. Furthermore, electron and super-resolution microscopies showed that synaptic SNAREs and Caveolin coexpression led to the partial loss of the cisternae, suggesting their fusion with the plasma membrane. In summary, we propose that this assay reconstitutes membrane fusion in a simple organism with an easy-to-observe phenotype and is amenable to structure-function studies of SNAREs.
Collapse
Affiliation(s)
- Soledad Ferreras
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Membrane Traffic in Healthy & Diseased Brain, Paris, France
| | - Neha Pratap Singh
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Membrane Traffic in Healthy & Diseased Brain, Paris, France
| | - Remi Le Borgne
- Université Paris Cité, CNRS, UMR7592, Institut Jacques Monod, Paris, France
| | - Philippe Bun
- Université Paris Cité, NeurImag, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Thomas Binz
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Robert G Parton
- The University of Queensland, Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, Qld, Brisbane, Australia
| | | | - Christian Vannier
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Membrane Traffic in Healthy & Diseased Brain, Paris, France.
| | - Thierry Galli
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Membrane Traffic in Healthy & Diseased Brain, Paris, France; GHU Paris psychiatrie neurosciences, Paris, France.
| |
Collapse
|
2
|
Bruguera ES, Mahoney JP, Weis WI. Reconstitution of purified membrane protein dimers in lipid nanodiscs with defined stoichiometry and orientation using a split GFP tether. J Biol Chem 2022; 298:101628. [PMID: 35074428 PMCID: PMC8980801 DOI: 10.1016/j.jbc.2022.101628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 12/12/2022] Open
Abstract
Many membrane proteins function as dimers or larger oligomers, including transporters, channels, certain signaling receptors, and adhesion molecules. In some cases, the interactions between individual proteins may be weak and/or dependent on specific lipids, such that detergent solubilization used for biochemical and structural studies disrupts functional oligomerization. Solubilized membrane protein oligomers can be captured in lipid nanodiscs, but this is an inefficient process that can produce stoichiometrically and topologically heterogeneous preparations. Here, we describe a technique to obtain purified homogeneous membrane protein dimers in nanodiscs using a split GFP (sGFP) tether. Complementary sGFP tags associate to tether the coexpressed dimers and control both stoichiometry and orientation within the nanodiscs, as assessed by quantitative Western blotting and negative-stain EM. The sGFP tether confers several advantages over other methods: it is highly stable in solution and in SDS-PAGE, which facilitates screening of dimer expression and purification by fluorescence, and also provides a dimer-specific purification handle for use with GFP nanobody–conjugated resin. We used this method to purify a Frizzled-4 homodimer and a Frizzled-4/low-density lipoprotein receptor–related protein 6 heterodimer in nanodiscs. These examples demonstrate the utility and flexibility of this method, which enables subsequent mechanistic molecular and structural studies of membrane protein pairs.
Collapse
Affiliation(s)
- Elise S Bruguera
- Departments of Molecular & Cellular Physiology and Structural Biology, Stanford University School of Medicine; Stanford, CA 94305
| | - Jacob P Mahoney
- Departments of Molecular & Cellular Physiology and Structural Biology, Stanford University School of Medicine; Stanford, CA 94305
| | - William I Weis
- Departments of Molecular & Cellular Physiology and Structural Biology, Stanford University School of Medicine; Stanford, CA 94305.
| |
Collapse
|
3
|
Jaimon E, Tripathi A, Khurana A, Ghosh D, Sugatha J, Datta S. Binding with heat shock cognate protein HSC70 fine-tunes the Golgi association of the small GTPase ARL5B. J Biol Chem 2021; 297:101422. [PMID: 34798070 PMCID: PMC8661063 DOI: 10.1016/j.jbc.2021.101422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/04/2021] [Accepted: 11/08/2021] [Indexed: 12/30/2022] Open
Abstract
ARL5B, an ARF-like small GTPase localized to the trans-Golgi, is known for regulating endosome-Golgi trafficking and promoting the migration and invasion of breast cancer cells. Although a few interacting partners have been identified, the mechanism of the shuttling of ARL5B between the Golgi membrane and the cytosol is still obscure. Here, using GFP-binding protein (GBP) pull-down followed by mass spectrometry, we identified heat shock cognate protein (HSC70) as an additional interacting partner of ARL5B. Our pull-down and isothermal titration calorimetry (ITC)-based studies suggested that HSC70 binds to ARL5B in an ADP-dependent manner. Additionally, we showed that the N-terminal helix and the nucleotide status of ARL5B contribute to its recognition by HSC70. The confocal microscopy and cell fractionation studies in MDA-MB-231 breast cancer cells revealed that the depletion of HSC70 reduces the localization of ARL5B to the Golgi. Using in vitro reconstitution approach, we provide evidence that HSC70 fine-tunes the association of ARL5B with Golgi membrane. Finally, we demonstrated that the interaction between ARL5B and HSC70 is important for the localization of cation independent mannose-6-phosphate receptor (CIMPR) at Golgi. Collectively, we propose a mechanism by which HSC70, a constitutively expressed chaperone, modulates the Golgi association of ARL5B, which in turn has implications for the Golgi-associated functions of this GTPase.
Collapse
Affiliation(s)
- Ebsy Jaimon
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Aashutosh Tripathi
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Arohi Khurana
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Dipanjana Ghosh
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Jini Sugatha
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Sunando Datta
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India.
| |
Collapse
|
4
|
Fisher ME, Bovo E, Aguayo-Ortiz R, Cho EE, Pribadi MP, Dalton MP, Rathod N, Lemieux MJ, Espinoza-Fonseca LM, Robia SL, Zima AV, Young HS. Dwarf open reading frame (DWORF) is a direct activator of the sarcoplasmic reticulum calcium pump SERCA. eLife 2021; 10:65545. [PMID: 34075877 PMCID: PMC8203291 DOI: 10.7554/elife.65545] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 06/01/2021] [Indexed: 01/05/2023] Open
Abstract
The sarco-plasmic reticulum calcium pump (SERCA) plays a critical role in the contraction-relaxation cycle of muscle. In cardiac muscle, SERCA is regulated by the inhibitor phospholamban. A new regulator, dwarf open reading frame (DWORF), has been reported to displace phospholamban from SERCA. Here, we show that DWORF is a direct activator of SERCA, increasing its turnover rate in the absence of phospholamban. Measurement of in-cell calcium dynamics supports this observation and demonstrates that DWORF increases SERCA-dependent calcium reuptake. These functional observations reveal opposing effects of DWORF activation and phospholamban inhibition of SERCA. To gain mechanistic insight into SERCA activation, fluorescence resonance energy transfer experiments revealed that DWORF has a higher affinity for SERCA in the presence of calcium. Molecular modeling and molecular dynamics simulations provide a model for DWORF activation of SERCA, where DWORF modulates the membrane bilayer and stabilizes the conformations of SERCA that predominate during elevated cytosolic calcium.
Collapse
Affiliation(s)
- M'Lynn E Fisher
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Rodrigo Aguayo-Ortiz
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, United States
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Marsha P Pribadi
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Michael P Dalton
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Nishadh Rathod
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, United States
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| |
Collapse
|
5
|
Nguyen N, Olivas TJ, Mires A, Jin J, Yu S, Luan L, Nag S, Kauffman KJ, Melia TJ. The insufficiency of ATG4A in macroautophagy. J Biol Chem 2020; 295:13584-13600. [PMID: 32732290 DOI: 10.1074/jbc.ra120.013897] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/21/2020] [Indexed: 12/17/2022] Open
Abstract
During autophagy, LC3 and GABARAP proteins become covalently attached to phosphatidylethanolamine on the growing autophagosome. This attachment is also reversible. Deconjugation (or delipidation) involves the proteolytic cleavage of an isopeptide bond between LC3 or GABARAP and the phosphatidylethanolamine headgroup. This cleavage is carried about by the ATG4 family of proteases (ATG4A, B, C, and D). Many studies have established that ATG4B is the most active of these proteases and is sufficient for autophagy progression in simple cells. Here we examined the second most active protease, ATG4A, to map out key regulatory motifs on the protein and to establish its activity in cells. We utilized fully in vitro reconstitution systems in which we controlled the attachment of LC3/GABARAP members and discovered a role for a C-terminal LC3-interacting region on ATG4A in regulating its access to LC3/GABARAP. We then used a gene-edited cell line in which all four ATG4 proteases have been knocked out to establish that ATG4A is insufficient to support autophagy and is unable to support GABARAP proteins removal from the membrane. As a result, GABARAP proteins accumulate on membranes other than mature autophagosomes. These results suggest that to support efficient production and consumption of autophagosomes, additional factors are essential including possibly ATG4B itself or one of its proteolytic products in the LC3 family.
Collapse
Affiliation(s)
- Nathan Nguyen
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Taryn J Olivas
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Antonio Mires
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA; National Agrarian University-La Molina, Lima, Peru
| | - Jiaxin Jin
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA; Lanzhou University Second Hospital, Lanzhou, Gansu Province, China
| | - Shenliang Yu
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Lin Luan
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Shanta Nag
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Karlina J Kauffman
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Thomas J Melia
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA.
| |
Collapse
|
6
|
Soysa HSM, Aunkham A, Schulte A, Suginta W. Single-channel properties, sugar specificity, and role of chitoporin in adaptive survival of Vibrio cholerae type strain O1. J Biol Chem 2020; 295:9421-9432. [PMID: 32409576 DOI: 10.1074/jbc.ra120.012921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/12/2020] [Indexed: 11/06/2022] Open
Abstract
Vibrio cholerae is a Gram-negative, facultative anaerobic bacterial species that causes serious disease and can grow on various carbon sources, including chitin polysaccharides. In saltwater, its attachment to chitin surfaces not only serves as the initial step of nutrient recruitment but is also a crucial mechanism underlying cholera epidemics. In this study, we report the first characterization of a chitooligosaccharide-specific chitoporin, VcChiP, from the cell envelope of the V. cholerae type strain O1. We modeled the structure of VcChiP, revealing a trimeric cylinder that forms single channels in phospholipid bilayers. The membrane-reconstituted VcChiP channel was highly dynamic and voltage induced. Substate openings O1', O2', and O3', between the fully open states O1, O2, and O3, were polarity selective, with nonohmic conductance profiles. Results of liposome-swelling assays suggested that VcChiP can transport monosaccharides, as well as chitooligosaccharides, but not other oligosaccharides. Of note, an outer-membrane porin (omp)-deficient strain of Escherichia coli expressing heterologous VcChiP could grow on M9 minimal medium supplemented with small chitooligosaccharides. These results support a crucial role of chitoporin in the adaptive survival of bacteria on chitinous nutrients. Our findings also suggest a promising means of vaccine development based on surface-exposed outer-membrane proteins and the design of novel anticholera agents based on chitooligosaccharide-mimicking analogs.
Collapse
Affiliation(s)
| | - Anuwat Aunkham
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Payupnai, Rayong, Thailand
| | - Albert Schulte
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Payupnai, Rayong, Thailand
| | - Wipa Suginta
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Payupnai, Rayong, Thailand
| |
Collapse
|
7
|
Taniguchi S, Toyoshima M, Takamatsu T, Mima J. Curvature-sensitive trans-assembly of human Atg8-family proteins in autophagy-related membrane tethering. Protein Sci 2020; 29:1387-1400. [PMID: 31960529 DOI: 10.1002/pro.3828] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/15/2020] [Accepted: 01/15/2020] [Indexed: 12/18/2022]
Abstract
In macroautophagy, de novo formation of the double membrane-bound organelles, termed autophagosomes, is essential for engulfing and sequestering the cytoplasmic contents to be degraded in the lytic compartments such as vacuoles and lysosomes. Atg8-family proteins have been known to be responsible for autophagosome formation via membrane tethering and fusion events of precursor membrane structures. Nevertheless, how Atg8 proteins act directly upon autophagosome formation still remains enigmatic. Here, to further gain molecular insights into Atg8-mediated autophagic membrane dynamics, we study the two representative human Atg8 orthologs, LC3B and GATE-16, by quantitatively evaluating their intrinsic potency to physically tether lipid membranes in a chemically defined reconstitution system using purified Atg8 proteins and synthetic liposomes. Both LC3B and GATE-16 retained the capacities to trigger efficient membrane tethering at the protein-to-lipid molar ratios ranging from 1:100 to 1:5,000. These human Atg8-mediated membrane-tethering reactions require trans-assembly between the membrane-anchored forms of LC3B and GATE-16 and can be reversibly and strictly controlled by the membrane attachment and detachment cycles. Strikingly, we further uncovered distinct membrane curvature dependences of LC3B- and GATE-16-mediated membrane tethering reactions: LC3B can drive tethering more efficiently than GATE-16 for highly curved small vesicles (e.g., 50 nm in diameter), although GATE-16 turns out to be a more potent tether than LC3B for flatter large vesicles (e.g., 200 and 400 nm in diameter). Our findings establish curvature-sensitive trans-assembly of human Atg8-family proteins in reconstituted membrane tethering, which recapitulates an essential subreaction of the biogenesis of autophagosomes in vivo.
Collapse
Affiliation(s)
- Saki Taniguchi
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | | | - Tomoyo Takamatsu
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | - Joji Mima
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| |
Collapse
|
8
|
Śmigiel WM, Lefrançois P, Poolman B. Physicochemical considerations for bottom-up synthetic biology. Emerg Top Life Sci 2019; 3:445-58. [PMID: 33523159 DOI: 10.1042/ETLS20190017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/05/2019] [Accepted: 08/07/2019] [Indexed: 12/18/2022]
Abstract
The bottom-up construction of synthetic cells from molecular components is arguably one of the most challenging areas of research in the life sciences. We review the impact of confining biological systems in synthetic vesicles. Complex cell-like systems require control of the internal pH, ionic strength, (macro)molecular crowding, redox state and metabolic energy conservation. These physicochemical parameters influence protein activity and need to be maintained within limits to ensure the system remains in steady-state. We present the physicochemical considerations for building synthetic cells with dimensions ranging from the smallest prokaryotes to eukaryotic cells.
Collapse
|
9
|
Segawa K, Tamura N, Mima J. Homotypic and heterotypic trans-assembly of human Rab-family small GTPases in reconstituted membrane tethering. J Biol Chem 2019; 294:7722-7739. [PMID: 30910814 DOI: 10.1074/jbc.ra119.007947] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/07/2019] [Indexed: 11/06/2022] Open
Abstract
Membrane tethering is a highly regulated event occurring during the initial physical contact between membrane-bounded transport carriers and their target subcellular membrane compartments, thereby ensuring the spatiotemporal specificity of intracellular membrane trafficking. Although Rab-family small GTPases and specific Rab-interacting effectors, such as coiled-coil tethering proteins and multisubunit tethering complexes, are known to be involved in membrane tethering, how these protein components directly act upon the tethering event remains enigmatic. Here, using a chemically defined reconstitution system, we investigated the molecular basis of membrane tethering by comprehensively and quantitatively evaluating the intrinsic capacities of 10 representative human Rab-family proteins (Rab1a, -3a, -4a, -5a, -6a, -7a, -9a, -11a, -27a, and -33b) to physically tether two distinct membranes via homotypic and heterotypic Rab-Rab assembly. All of the Rabs tested, except Rab27a, specifically caused homotypic membrane tethering at physiologically relevant Rab densities on membrane surfaces (e.g. Rab/lipid molar ratios of 1:100-1:3,000). Notably, endosomal Rab5a retained its intrinsic potency to drive efficient homotypic tethering even at concentrations below the Rab/lipid ratio of 1:3,000. Comprehensive reconstitution experiments further uncovered that heterotypic combinations of human Rab-family isoforms, including Rab1a/6a, Rab1a/9a, and Rab1a/33b, can directly and selectively mediate membrane tethering. Rab1a and Rab9a in particular synergistically triggered very rapid and efficient membrane tethering reactions through their heterotypic trans-assembly on two opposing membranes. In conclusion, our findings establish that, in the physiological context, homotypic and heterotypic trans-assemblies of Rab-family small GTPases can provide the essential molecular machinery necessary to drive membrane tethering in eukaryotic endomembrane systems.
Collapse
Affiliation(s)
- Kazuya Segawa
- From the Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Naoki Tamura
- From the Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Joji Mima
- From the Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| |
Collapse
|
10
|
Oliver D. Substrate Proteins Take Shape at an Improved Bacterial Translocon. J Bacteriol 2019; 201:e00618-18. [PMID: 30322856 DOI: 10.1128/JB.00618-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 10/12/2018] [Indexed: 11/20/2022] Open
Abstract
Characterization of Sec-dependent bacterial protein transport has often relied on an in vitro protein translocation system comprised in part of Escherichia coli inverted inner membrane vesicles or, more recently, purified SecYEG translocons reconstituted into liposomes using mostly a single substrate (proOmpA). A paper published in this issue (P. Bariya and L. Randall, J Bacteriol 201:e00493-18, 2019, https://doi.org/10.1128/JB.00493-18) finds that inclusion of SecA protein during SecYEG proteoliposome reconstitution dramatically improves the number of active translocons. This experimentally useful and intriguing result that may arise from SecA membrane integration properties is discussed here. Furthermore, determination of the rate-limiting transport step for nine different substrates implicates the mature region distal to the signal peptide in the observed rate constant differences, indicating that more nuanced transport models that respond to differences in protein sequence and structure are needed.
Collapse
|
11
|
Shen C, Liu Y, Yu H, Gulbranson DR, Kogut I, Bilousova G, Zhang C, Stowell MHB, Shen J. The N-peptide-binding mode is critical to Munc18-1 function in synaptic exocytosis. J Biol Chem 2018; 293:18309-18317. [PMID: 30275014 DOI: 10.1074/jbc.ra118.005254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/25/2018] [Indexed: 01/09/2023] Open
Abstract
Sec1/Munc18 (SM) proteins promote intracellular vesicle fusion by binding to N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). A key SNARE-binding mode of SM proteins involves the N-terminal peptide (N-peptide) motif of syntaxin, a SNARE subunit localized to the target membrane. In in vitro membrane fusion assays, inhibition of N-peptide motif binding previously has been shown to abrogate the stimulatory function of Munc18-1, a SM protein involved in synaptic exocytosis in neurons. The physiological role of the N-peptide-binding mode, however, remains unclear. In this work, we addressed this key question using a "clogged" Munc18-1 protein, in which an ectopic copy of the syntaxin N-peptide motif was directly fused to Munc18-1. We found that the ectopic N-peptide motif blocks the N-peptide-binding pocket of Munc18-1, preventing the latter from binding to the native N-peptide motif on syntaxin-1. In a reconstituted system, we observed that clogged Munc18-1 is defective in promoting SNARE zippering. When introduced into induced neuronal cells (iN cells) derived from human pluripotent stem cells, clogged Munc18-1 failed to mediate synaptic exocytosis. As a result, both spontaneous and evoked synaptic transmission was abolished. These genetic findings provide direct evidence for the crucial role of the N-peptide-binding mode of Munc18-1 in synaptic exocytosis. We suggest that clogged SM proteins will also be instrumental in defining the physiological roles of the N-peptide-binding mode in other vesicle-fusion pathways.
Collapse
Affiliation(s)
- Chong Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Yinghui Liu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,; the Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Haijia Yu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,; the Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China,.
| | - Daniel R Gulbranson
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Igor Kogut
- the Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Ganna Bilousova
- the Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Chen Zhang
- the School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
| | - Michael H B Stowell
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Jingshi Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,.
| |
Collapse
|
12
|
Andra KK, Dorsey S, Royer CA, Menon AK. Structural mapping of fluorescently-tagged, functional nhTMEM16 scramblase in a lipid bilayer. J Biol Chem 2018; 293:12248-12258. [PMID: 29903908 DOI: 10.1074/jbc.ra118.003648] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/12/2018] [Indexed: 01/25/2023] Open
Abstract
Most members of the TransMEMbrane protein 16 (TMEM16) family are Ca2+-regulated scramblases that facilitate the bidirectional movement of phospholipids across membranes necessary for diverse physiological processes. The nhTMEM16 scramblase (from the fungus Nectria hematococca) is a homodimer with a large cytoplasmic region and a hydrophilic, membrane-exposed groove in each monomer. The groove provides the transbilayer conduit for lipids, but the mechanism by which Ca2+ regulates it is not clear. Because fusion of large protein tags at either the N or C terminus abolishes nhTMEM16 activity, we hypothesized that its cytoplasmic portion containing both termini may regulate lipid translocation via a Ca2+-dependent conformational change. To test this hypothesis, here we used fluorescence methods to map key distances within the nhTMEM16 homodimer and between its termini and the membrane. To this end, we developed functional nhTMEM16 variants bearing an acyl carrier protein (ACP) tag at one or both of the termini. These constructs were fluorescently labeled by ACP synthase-mediated insertion of CoA-conjugated fluorophores and reconstituted into vesicles containing fluorescent lipids to obtain the distance of closest approach between the labeled tag and the membrane via FRET. Fluorescence lifetime measurements with phasor analysis were used to determine the distance between the N and C termini of partnering monomers in the nhTMEM16 homodimer. We now report that the measured distances do not vary significantly between Ca2+-replete and EGTA-treated samples, indicating that whereas the cytoplasmic portion of the protein is important for function, it does not appear to regulate scramblase activity via a detectable conformational change.
Collapse
Affiliation(s)
- Kiran K Andra
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065
| | - Savanna Dorsey
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Catherine A Royer
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065.
| |
Collapse
|
13
|
Yavuz H, Kattan I, Hernandez JM, Hofnagel O, Witkowska A, Raunser S, Walla PJ, Jahn R. Arrest of trans-SNARE zippering uncovers loosely and tightly docked intermediates in membrane fusion. J Biol Chem 2018; 293:8645-8655. [PMID: 29666192 PMCID: PMC5986196 DOI: 10.1074/jbc.ra118.003313] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Indexed: 12/03/2022] Open
Abstract
Soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) proteins mediate intracellular membrane fusion in the secretory pathway. They contain conserved regions, termed SNARE motifs, that assemble between opposing membranes directionally from their N termini to their membrane-proximal C termini in a highly exergonic reaction. However, how this energy is utilized to overcome the energy barriers along the fusion pathway is still under debate. Here, we have used mutants of the SNARE synaptobrevin to arrest trans-SNARE zippering at defined stages. We have uncovered two distinct vesicle docking intermediates where the membranes are loosely and tightly connected, respectively. The tightly connected state is irreversible and independent of maintaining assembled SNARE complexes. Together, our results shed new light on the intermediate stages along the pathway of membrane fusion.
Collapse
Affiliation(s)
| | - Iman Kattan
- Biomolecular Spectroscopy and Single-Molecule Detection Research Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Javier M Hernandez
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | | | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Peter J Walla
- Biomolecular Spectroscopy and Single-Molecule Detection Research Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.,Biomolecular Spectroscopy and Single-Molecule Detection Research Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | | |
Collapse
|
14
|
Ghai I, Bajaj H, Arun Bafna J, El Damrany Hussein HA, Winterhalter M, Wagner R. Ampicillin permeation across OmpF, the major outer-membrane channel in Escherichia coli. J Biol Chem 2018. [PMID: 29540483 DOI: 10.1074/jbc.ra117.000705] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The outer cell wall of the Gram-negative bacteria is a crucial barrier for antibiotics to reach their target. Here, we show that the chemical stability of the widely used antibiotic ampicillin is a major factor in the permeation across OmpF to reach the target in the periplasm. Using planar lipid bilayers we investigated the interactions and permeation of OmpF with ampicillin, its basic pH-induced primary degradation product (penicilloic acid), and the chemically more stable benzylpenicillin. We found that the solute-induced ion current fluctuation is 10 times higher with penicilloic acid than with ampicillin. Furthermore, we also found that ampicillin can easily permeate through OmpF, at an ampicillin gradient of 10 μm and a conductance of Gamp ≅ 3.8 fS, with a flux rate of roughly 237 molecules/s of ampicillin at Vm = 10 mV. The structurally related benzylpenicillin yields a lower conductance of Gamp ≅ 2 fS, corresponding to a flux rate of ≈120 molecules/s. In contrast, the similar sized penicilloic acid was nearly unable to permeate through OmpF. MD calculations show that, besides their charge difference, the main differences between ampicillin and penicilloic acid are the shape of the molecules, and the strength and direction of the dipole vector. Our results show that OmpF can impose selective permeation on similar sized molecules based on their structure and their dipolar properties.
Collapse
Affiliation(s)
- Ishan Ghai
- From the Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany
| | - Harsha Bajaj
- From the Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany
| | - Jayesh Arun Bafna
- From the Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany
| | | | - Mathias Winterhalter
- From the Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany
| | - Richard Wagner
- From the Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany
| |
Collapse
|
15
|
Abstract
Membrane fusion is essential for intracellular protein sorting, cell growth, hormone secretion, and neurotransmission. Rapid membrane fusion requires tethering and Sec1-Munc18 (SM) function to catalyze R-, Qa-, Qb-, and Qc-SNARE complex assembly in trans, as well as SNARE engagement by the SNARE-binding chaperone Sec17/αSNAP. The hexameric vacuolar HOPS (homotypic fusion and vacuole protein sorting) complex in the yeast Saccharomyces cerevisiae tethers membranes through its affinities for the membrane Rab GTPase Ypt7. HOPS also has specific affinities for the vacuolar SNAREs and catalyzes SNARE complex assembly, but the order of their assembly into a 4-SNARE complex is unclear. We now report defined assembly intermediates on the path to membrane fusion. We found that a prefusion intermediate will assemble with HOPS and the R, Qa, and Qc SNAREs, and that this assembly undergoes rapid fusion upon addition of Qb and Sec17. HOPS-tethered membranes and all four vacuolar SNAREs formed a complex that underwent an even more dramatic burst of fusion upon Sec17p addition. These findings provide initial insights into an ordered fusion pathway consisting of the following intermediates and events: 1) Rab- and HOPS-tethered membranes, 2) a HOPS:R:Qa:Qc trans-complex, 3) a HOPS:4-SNARE trans-complex, 4) an engagement with Sec17, and 5) the rapid lipid rearrangements during fusion. In conclusion, our results indicate that the R:Qa:Qc complex forms in the context of membrane, Ypt7, HOPS, and trans-SNARE assembly and serves as a functional intermediate for rapid fusion after addition of the Qb-SNARE and Sec17 proteins.
Collapse
Affiliation(s)
- Max Harner
- From the Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755-3844
| | - William Wickner
- From the Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755-3844
| |
Collapse
|
16
|
Pierman B, Toussaint F, Bertin A, Lévy D, Smargiasso N, De Pauw E, Boutry M. Activity of the purified plant ABC transporter NtPDR1 is stimulated by diterpenes and sesquiterpenes involved in constitutive and induced defenses. J Biol Chem 2017; 292:19491-19502. [PMID: 28972149 PMCID: PMC5702685 DOI: 10.1074/jbc.m117.811935] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/22/2017] [Indexed: 11/06/2022] Open
Abstract
Within the plant ATP-binding cassette transporter family, pleiotropic drug resistance (PDR) transporters play essential functions, such as in hormone transport or defense against biotic and abiotic stresses. NtPDR1 from Nicotiana tabacum has been shown to be involved in the constitutive defense against pathogens through the secretion of toxic cyclic diterpenes, such as the antimicrobial substrates cembrene and sclareol from the leaf hairs (trichomes). However, direct evidence of an interaction between NtPDR1 and terpenes is lacking. Here, we stably expressed NtPDR1 in N. tabacum BY-2 suspension cells. NtPDR1 was purified as an active monomer glycosylated at a single site in the third external loop. NtPDR1 reconstitution in proteoliposomes stimulated its basal ATPase activity from 21 to 38 nmol of Pi·mg-1·min-1, and ATPase activity was further stimulated by the NtPDR1 substrates cembrene and sclareol, providing direct evidence of an interaction between NtPDR1 and its two substrates. Interestingly, NtPDR1 was also stimulated by capsidiol, a sesquiterpene produced by N. tabacum upon pathogen attack. We also monitored the transcriptional activity from the NtPDR1 promoter in situ with a reporter gene and found that, although NtPDR1 expression was limited to trichomes under normal conditions, addition of methyl jasmonate, a biotic stress hormone, induced expression in all leaf tissues. This finding indicated that NtPDR1 is involved not only in constitutive but also in induced plant defenses. In conclusion, we provide direct evidence of an interaction between the NtPDR1 transporter and its substrates and that NtPDR1 transports compounds involved in both constitutive (diterpenes) and induced (sesquiterpenes) plant defenses.
Collapse
Affiliation(s)
- Baptiste Pierman
- From the Institut des Sciences de la Vie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Frédéric Toussaint
- From the Institut des Sciences de la Vie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Aurélie Bertin
- the Laboratoire Physico Chimie Curie, Institut Curie, Paris Sciences et Lettres Research University, CNRS UMR168, and Sorbonne Universités, Université Pierre et Marie Curie Paris 06, 75005 Paris, France, and
| | - Daniel Lévy
- the Laboratoire Physico Chimie Curie, Institut Curie, Paris Sciences et Lettres Research University, CNRS UMR168, and Sorbonne Universités, Université Pierre et Marie Curie Paris 06, 75005 Paris, France, and
| | - Nicolas Smargiasso
- Mass Spectrometry Laboratory, Molecular Systems Research Unit, University of Liège, B-4000 Liège, Belgium
| | - Edwin De Pauw
- Mass Spectrometry Laboratory, Molecular Systems Research Unit, University of Liège, B-4000 Liège, Belgium
| | - Marc Boutry
- From the Institut des Sciences de la Vie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium,
| |
Collapse
|
17
|
Inoshita M, Mima J. Human Rab small GTPase- and class V myosin-mediated membrane tethering in a chemically defined reconstitution system. J Biol Chem 2017; 292:18500-18517. [PMID: 28939769 DOI: 10.1074/jbc.m117.811356] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/21/2017] [Indexed: 12/13/2022] Open
Abstract
Membrane tethering is a fundamental process essential for the compartmental specificity of intracellular membrane trafficking in eukaryotic cells. Rab-family small GTPases and specific sets of Rab-interacting effector proteins, including coiled-coil tethering proteins and multisubunit tethering complexes, are reported to be responsible for membrane tethering. However, whether and how these key components directly and specifically tether subcellular membranes remains enigmatic. Using chemically defined proteoliposomal systems reconstituted with purified human Rab proteins and synthetic liposomal membranes to study the molecular basis of membrane tethering, we established here that Rab-family GTPases have a highly conserved function to directly mediate membrane tethering, even in the absence of any types of Rab effectors such as the so-called tethering proteins. Moreover, we demonstrate that membrane tethering mediated by endosomal Rab11a is drastically and selectively stimulated by its cognate Rab effectors, class V myosins (Myo5A and Myo5B), in a GTP-dependent manner. Of note, Myo5A and Myo5B exclusively recognized and cooperated with the membrane-anchored form of their cognate Rab11a to support membrane tethering mediated by trans-Rab assemblies on opposing membranes. Our findings support the novel concept that Rab-family proteins provide a bona fide membrane tether to physically and specifically link two distinct lipid bilayers of subcellular membranes. They further indicate that Rab-interacting effector proteins, including class V myosins, can regulate these Rab-mediated membrane-tethering reactions.
Collapse
Affiliation(s)
- Motoki Inoshita
- From the Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Joji Mima
- From the Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| |
Collapse
|
18
|
Tichá A, Stanchev S, Škerle J, Began J, Ingr M, Švehlová K, Polovinkin L, Růžička M, Bednárová L, Hadravová R, Poláchová E, Rampírová P, Březinová J, Kašička V, Majer P, Strisovsky K. Sensitive Versatile Fluorogenic Transmembrane Peptide Substrates for Rhomboid Intramembrane Proteases. J Biol Chem 2017; 292:2703-2713. [PMID: 28069810 DOI: 10.1074/jbc.m116.762849] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/05/2017] [Indexed: 11/06/2022] Open
Abstract
Rhomboid proteases are increasingly being explored as potential drug targets, but their potent and specific inhibitors are not available, and strategies for inhibitor development are hampered by the lack of widely usable and easily modifiable in vitro activity assays. Here we address this bottleneck and report on the development of new fluorogenic transmembrane peptide substrates, which are cleaved by several unrelated rhomboid proteases, can be used both in detergent micelles and in liposomes, and contain red-shifted fluorophores that are suitable for high-throughput screening of compound libraries. We show that nearly the entire transmembrane domain of the substrate is important for efficient cleavage, implying that it extensively interacts with the enzyme. Importantly, we demonstrate that in the detergent micelle system, commonly used for the enzymatic analyses of intramembrane proteolysis, the cleavage rate strongly depends on detergent concentration, because the reaction proceeds only in the micelles. Furthermore, we show that the catalytic efficiency and selectivity toward a rhomboid substrate can be dramatically improved by targeted modification of the sequence of its P5 to P1 region. The fluorogenic substrates that we describe and their sequence variants should find wide use in the detection of activity and development of inhibitors of rhomboid proteases.
Collapse
Affiliation(s)
- Anežka Tichá
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10.,the First Faculty of Medicine, Charles University, Kateřinská 32, Prague 121 08, and
| | - Stancho Stanchev
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Jan Škerle
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10.,the Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030/8, Prague 128 43
| | - Jakub Began
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10.,the Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, Prague 128 44
| | - Marek Ingr
- the Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030/8, Prague 128 43.,the Department of Physics and Materials Engineering, Tomas Bata University in Zlín, Faculty of Technology, nám. T.G. Masaryka 5555, 76001, Zlín, Czech Republic
| | - Kateřina Švehlová
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Lucie Polovinkin
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10.,the Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030/8, Prague 128 43
| | - Martin Růžička
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10.,the Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030/8, Prague 128 43
| | - Lucie Bednárová
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Romana Hadravová
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Edita Poláchová
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Petra Rampírová
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Jana Březinová
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Václav Kašička
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Pavel Majer
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10
| | - Kvido Strisovsky
- From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo n. 2, Prague 166 10,
| |
Collapse
|
19
|
Li H, Sineshchekov OA, Wu G, Spudich JL. In Vitro Activity of a Purified Natural Anion Channelrhodopsin. J Biol Chem 2016; 291:25319-25325. [PMID: 27789708 DOI: 10.1074/jbc.c116.760041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/26/2016] [Indexed: 12/29/2022] Open
Abstract
Natural anion channelrhodopsins (ACRs) recently discovered in cryptophyte algae are the most active rhodopsin channels known. They are of interest both because of their unique natural function of light-gated chloride conductance and because of their unprecedented efficiency of membrane hyperpolarization for optogenetic neuron silencing. Light-induced currents of ACRs have been studied in HEK cells and neurons, but light-gated channel conductance of ACRs in vitro has not been demonstrated. Here we report light-induced chloride channel activity of a purified ACR protein reconstituted in large unilamellar vesicles (LUVs). EPR measurements establish that the channels are inserted uniformly "inside-out" with their cytoplasmic surface facing the medium of the LUV suspension. We show by time-resolved flash spectroscopy that the photochemical reaction cycle of a functional purified ACR from Guillardia theta (GtACR1) in LUVs exhibits similar spectral shifts, indicating similar photocycle intermediates as GtACR1 in detergent micelles. Furthermore, the photocycle rate is dependent on electric potential generated by chloride gradients in the LUVs in the same manner as in voltage-clamped animal cells. We confirm with this system that, in contrast to cation-conducting channelrhodopsins, opening of the channel occurs prior to deprotonation of the Schiff base. However, the photointermediate transitions in the LUVs exhibit faster kinetics. The ACR-incorporated LUVs provide a purified defined system amenable to EPR, optical and vibrational spectroscopy, and fluorescence resonance energy transfer measurements of structural changes of ACRs with the molecules in a demonstrably functional state.
Collapse
Affiliation(s)
- Hai Li
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030 and
| | - Oleg A Sineshchekov
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030 and
| | - Gang Wu
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030 and.,the Department of Internal Medicine, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030
| | - John L Spudich
- From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030 and
| |
Collapse
|
20
|
Colombo SF, Cardani S, Maroli A, Vitiello A, Soffientini P, Crespi A, Bram RF, Benfante R, Borgese N. Tail-anchored Protein Insertion in Mammals: FUNCTION AND RECIPROCAL INTERACTIONS OF THE TWO SUBUNITS OF THE TRC40 RECEPTOR. J Biol Chem 2016; 291:15292-306. [PMID: 27226539 DOI: 10.1074/jbc.m115.707752] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Indexed: 11/06/2022] Open
Abstract
The GET (guided entry of tail-anchored proteins)/TRC (transmembrane recognition complex) pathway for tail-anchored protein targeting to the endoplasmic reticulum (ER) has been characterized in detail in yeast and is thought to function similarly in mammals, where the orthologue of the central ATPase, Get3, is known as TRC40 or Asna1. Get3/TRC40 function requires an ER receptor, which in yeast consists of the Get1/Get2 heterotetramer and in mammals of the WRB protein (tryptophan-rich basic protein), homologous to yeast Get1, in combination with CAML (calcium-modulating cyclophilin ligand), which is not homologous to Get2. To better characterize the mammalian receptor, we investigated the role of endogenous WRB and CAML in tail-anchored protein insertion as well as their association, concentration, and stoichiometry in rat liver microsomes and cultured cells. Functional proteoliposomes, reconstituted from a microsomal detergent extract, lost their activity when made with an extract depleted of TRC40-associated proteins or of CAML itself, whereas in vitro synthesized CAML and WRB together were sufficient to confer insertion competence to liposomes. CAML was found to be in ∼5-fold excess over WRB, and alteration of this ratio did not inhibit insertion. Depletion of each subunit affected the levels of the other one; in the case of CAML silencing, this effect was attributable to destabilization of the WRB transcript and not of WRB protein itself. These results reveal unanticipated complexity in the mutual regulation of the TRC40 receptor subunits and raise the question as to the role of the excess CAML in the mammalian ER.
Collapse
Affiliation(s)
- Sara Francesca Colombo
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| | - Silvia Cardani
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| | - Annalisa Maroli
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| | - Adriana Vitiello
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| | - Paolo Soffientini
- IFOM, the FIRC Institute for Molecular Oncology Foundation, Milan, Italy 20100 and
| | - Arianna Crespi
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| | | | - Roberta Benfante
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| | - Nica Borgese
- From the CNR Institute of Neuroscience and BIOMETRA Department, Università degli Studi di Milano and
| |
Collapse
|
21
|
Erokhova L, Horner A, Ollinger N, Siligan C, Pohl P. The Sodium Glucose Cotransporter SGLT1 Is an Extremely Efficient Facilitator of Passive Water Transport. J Biol Chem 2016; 291:9712-20. [PMID: 26945065 PMCID: PMC4850308 DOI: 10.1074/jbc.m115.706986] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/04/2016] [Indexed: 11/06/2022] Open
Abstract
The small intestine is void of aquaporins adept at facilitating vectorial water transport, and yet it reabsorbs ∼8 liters of fluid daily. Implications of the sodium glucose cotransporter SGLT1 in either pumping water or passively channeling water contrast with its reported water transporting capacity, which lags behind that of aquaporin-1 by 3 orders of magnitude. Here we overexpressed SGLT1 in MDCK cell monolayers and reconstituted the purified transporter into proteoliposomes. We observed the rate of osmotic proteoliposome deflation by light scattering. Fluorescence correlation spectroscopy served to assess (i) SGLT1 abundance in both vesicles and plasma membranes and (ii) flow-mediated dilution of an aqueous dye adjacent to the cell monolayer. Calculation of the unitary water channel permeability, pf, yielded similar values for cell and proteoliposome experiments. Neither the absence of glucose or Na(+), nor the lack of membrane voltage in vesicles, nor the directionality of water flow grossly altered pf Such weak dependence on protein conformation indicates that a water-impermeable occluded state (glucose and Na(+) in their binding pockets) lasts for only a minor fraction of the transport cycle or, alternatively, that occlusion of the substrate does not render the transporter water-impermeable as was suggested by computational studies of the bacterial homologue vSGLT. Although the similarity between the pf values of SGLT1 and aquaporin-1 makes a transcellular pathway plausible, it renders water pumping physiologically negligible because the passive flux would be orders of magnitude larger.
Collapse
Affiliation(s)
- Liudmila Erokhova
- From the Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Andreas Horner
- From the Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Nicole Ollinger
- From the Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Christine Siligan
- From the Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Peter Pohl
- From the Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria
| |
Collapse
|
22
|
Bischof LF, Friedrich C, Harms A, Søgaard-Andersen L, van der Does C. The Type IV Pilus Assembly ATPase PilB of Myxococcus xanthus Interacts with the Inner Membrane Platform Protein PilC and the Nucleotide-binding Protein PilM. J Biol Chem 2016; 291:6946-57. [PMID: 26851283 DOI: 10.1074/jbc.m115.701284] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 01/01/2023] Open
Abstract
Type IV pili (T4P) are ubiquitous bacterial cell surface structures, involved in processes such as twitching motility, biofilm formation, bacteriophage infection, surface attachment, virulence, and natural transformation. T4P are assembled by machinery that can be divided into the outer membrane pore complex, the alignment complex that connects components in the inner and outer membrane, and the motor complex in the inner membrane and cytoplasm. Here, we characterize the inner membrane platform protein PilC, the cytosolic assembly ATPase PilB of the motor complex, and the cytosolic nucleotide-binding protein PilM of the alignment complex of the T4P machinery ofMyxococcus xanthus PilC was purified as a dimer and reconstituted into liposomes. PilB was isolated as a monomer and bound ATP in a non-cooperative manner, but PilB fused to Hcp1 ofPseudomonas aeruginosaformed a hexamer and bound ATP in a cooperative manner. Hexameric but not monomeric PilB bound to PilC reconstituted in liposomes, and this binding stimulated PilB ATPase activity. PilM could only be purified when it was stabilized by a fusion with a peptide corresponding to the first 16 amino acids of PilN, supporting an interaction between PilM and PilN(1-16). PilM-N(1-16) was isolated as a monomer that bound but did not hydrolyze ATP. PilM interacted directly with PilB, but only with PilC in the presence of PilB, suggesting an indirect interaction. We propose that PilB interacts with PilC and with PilM, thus establishing the connection between the alignment and the motor complex.
Collapse
Affiliation(s)
- Lisa Franziska Bischof
- From the Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg and the Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, D-79104 Freiburg, Germany
| | - Carmen Friedrich
- From the Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg and
| | - Andrea Harms
- From the Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg and
| | - Lotte Søgaard-Andersen
- From the Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg and
| | - Chris van der Does
- From the Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg and the Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, D-79104 Freiburg, Germany
| |
Collapse
|
23
|
Zeitler M, Steringer JP, Müller HM, Mayer MP, Nickel W. HIV-Tat Protein Forms Phosphoinositide-dependent Membrane Pores Implicated in Unconventional Protein Secretion. J Biol Chem 2015; 290:21976-84. [PMID: 26183781 DOI: 10.1074/jbc.m115.667097] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 12/20/2022] Open
Abstract
HIV-Tat has been demonstrated to be secreted from cells in a phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-dependent manner. Here we show that HIV-Tat forms membrane-inserted oligomers, a process that is accompanied by changes in secondary structure with a strong increase in antiparallel β sheet content. Intriguingly, oligomerization of HIV-Tat on membrane surfaces leads to the formation of membrane pores, as demonstrated by physical membrane passage of small fluorescent tracer molecules. Although membrane binding of HIV-Tat did not strictly depend on PI(4,5)P2 but, rather, was mediated by a range of acidic membrane lipids, a functional interaction between PI(4,5)P2 and HIV-Tat was critically required for efficient membrane pore formation by HIV-Tat oligomers. These properties are strikingly similar to what has been reported previously for fibroblast growth factor 2 (FGF2), providing strong evidence of a common core mechanism of unconventional secretion shared by HIV-Tat and fibroblast growth factor 2.
Collapse
Affiliation(s)
- Marcel Zeitler
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Julia P Steringer
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Hans-Michael Müller
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Matthias P Mayer
- the Zentrum für Molekulare Biologie der Universität Heidelberg, Deutsches Krebsforschungszentrum-Zentrum für Molekulare Biologie der Universität Heidelberg Allianz, 69120 Heidelberg, Germany
| | - Walter Nickel
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| |
Collapse
|
24
|
Billen B, Brams M, Debaveye S, Remeeva A, Alpizar YA, Waelkens E, Kreir M, Brüggemann A, Talavera K, Nilius B, Voets T, Ulens C. Different ligands of the TRPV3 cation channel cause distinct conformational changes as revealed by intrinsic tryptophan fluorescence quenching. J Biol Chem 2015; 290:12964-74. [PMID: 25829496 PMCID: PMC4432310 DOI: 10.1074/jbc.m114.628925] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Indexed: 11/26/2022] Open
Abstract
TRPV3 is a thermosensitive ion channel primarily expressed in epithelial tissues of the skin, nose, and tongue. The channel has been implicated in environmental thermosensation, hyperalgesia in inflamed tissues, skin sensitization, and hair growth. Although transient receptor potential (TRP) channel research has vastly increased our understanding of the physiological mechanisms of nociception and thermosensation, the molecular mechanics of these ion channels are still largely elusive. In order to better comprehend the functional properties and the mechanism of action in TRP channels, high-resolution three-dimensional structures are indispensable, because they will yield the necessary insights into architectural intimacies at the atomic level. However, structural studies of membrane proteins are currently hampered by difficulties in protein purification and in establishing suitable crystallization conditions. In this report, we present a novel protocol for the purification of membrane proteins, which takes advantage of a C-terminal GFP fusion. Using this protocol, we purified human TRPV3. We show that the purified protein is a fully functional ion channel with properties akin to the native channel using planar patch clamp on reconstituted channels and intrinsic tryptophan fluorescence spectroscopy. Using intrinsic tryptophan fluorescence spectroscopy, we reveal clear distinctions in the molecular interaction of different ligands with the channel. Altogether, this study provides powerful tools to broaden our understanding of ligand interaction with TRPV channels, and the availability of purified human TRPV3 opens up perspectives for further structural and functional studies.
Collapse
Affiliation(s)
- Bert Billen
- From the Laboratory of Structural Neurobiology and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 601, 3000 Leuven, Belgium,
| | - Marijke Brams
- From the Laboratory of Structural Neurobiology and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 601, 3000 Leuven, Belgium
| | - Sarah Debaveye
- From the Laboratory of Structural Neurobiology and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 601, 3000 Leuven, Belgium
| | - Alina Remeeva
- From the Laboratory of Structural Neurobiology and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 601, 3000 Leuven, Belgium
| | - Yeranddy A Alpizar
- the Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 802, 3000 Leuven, Belgium
| | - Etienne Waelkens
- the Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 901, 3000 Leuven, Belgium, and
| | - Mohamed Kreir
- Nanion Technologies GmbH, Gabrielenstrasse 9, D-80636 Munich, Germany
| | - Andrea Brüggemann
- Nanion Technologies GmbH, Gabrielenstrasse 9, D-80636 Munich, Germany
| | - Karel Talavera
- the Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 802, 3000 Leuven, Belgium
| | - Bernd Nilius
- the Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 802, 3000 Leuven, Belgium
| | - Thomas Voets
- the Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 802, 3000 Leuven, Belgium
| | - Chris Ulens
- From the Laboratory of Structural Neurobiology and TRP Research Platform Leuven (TRPLe), Department of Cellular and Molecular Medicine, University of Leuven, Herestraat 49 Box 601, 3000 Leuven, Belgium
| |
Collapse
|
25
|
Han SG, Na JH, Lee WK, Park D, Oh J, Yoon SH, Lee CK, Sung MH, Shin YK, Yu YG. An amphipathic polypeptide derived from poly-γ-glutamic acid for the stabilization of membrane proteins. Protein Sci 2014; 23:1800-7. [PMID: 25283538 DOI: 10.1002/pro.2575] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 09/14/2014] [Accepted: 09/30/2014] [Indexed: 11/11/2022]
Abstract
Difficulties in the extraction of membrane proteins from cell membrane and their solubilization in native conformations have hindered their structural and biochemical analysis. To overcome these difficulties, an amphipathic polypeptide was synthesized by the conjugation of octyl and glucosyl groups to the carboxyl groups of poly-γ-glutamic acid (PGA). This polymer, called amphipathic PGA (APG), self-assembles as mono-disperse oligomers consisted of 4-5 monomers. APG shows significantly low value of critical micelle concentration and stabilization activity toward membrane proteins. Most of the sodium dodecyl sulfate (SDS)-solubilized membrane proteins from Escherichia coli remain soluble state in the presence of APG even after the removal of SDS. In addition, APG stabilizes purified 7 transmembrane proteins such as bacteriorhodopsin and human endothelin receptor Type A (ETA ) in their active conformations. Furthermore, ETA in complex with APG is readily inserted into liposomes without disrupting the integrity of liposomes. These properties of APG can be applied to overcome the difficulties in the stabilization and reconstitution of membrane proteins.
Collapse
Affiliation(s)
- Seong-Gu Han
- Department of Chemistry, Kookmin University, Seongbuk-gu, Seoul, 136-702, Republic of Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Kimura T, Yeliseev AA, Vukoti K, Rhodes SD, Cheng K, Rice KC, Gawrisch K. Recombinant cannabinoid type 2 receptor in liposome model activates g protein in response to anionic lipid constituents. J Biol Chem 2012; 287:4076-87. [PMID: 22134924 PMCID: PMC3281699 DOI: 10.1074/jbc.m111.268425] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 11/29/2011] [Indexed: 11/06/2022] Open
Abstract
Human cannabinoid type 2 (CB(2)) receptor expressed in Escherichia coli was purified and successfully reconstituted in the functional form into lipid bilayers composed of POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and cholesteryl hemisuccinate (CHS). Reconstitution was performed by detergent removal from the protein/lipid/detergent mixed micelles either on an adsorbent column, or by rapid dilution to below the critical micelle concentration of detergent followed by removal of detergent monomers on a concentrator. Proteoliposomes prepared at a protein/phospholipid/CHS molar ratio of 1/620-650/210-220 are free of detergent as shown by (1)H NMR, have a homogeneous protein/lipid ratio shown by isopycnic gradient ultracentrifugation, and are small in size with a mean diameter of 150-200 nm as measured by dynamic light scattering. Functional integrity of the reconstituted receptor was confirmed by quantitative binding of (2)H-labeled agonist CP-55,940-d(6) measured by (2)H magic angle spinning NMR, as well as by activation of G protein. The efficiency of G protein activation by agonist-bound CB(2) receptor was affected by negative electric surface potentials of proteoliposomes controlled by the content of anionic CHS or POPS. The activation was highest at an anionic lipid content of about 50 mol %. There was no correlation between the efficiency of G protein activation and an increase of hydrocarbon chain order induced by CHS or cholesterol. The results suggest the importance of anionic lipids in regulating signal transduction by CB(2) receptor and other class A GPCR. The successful reconstitution of milligram quantities of pure, functional CB(2) receptor enables a wide variety of structural studies.
Collapse
Affiliation(s)
- Tomohiro Kimura
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| | | | - Krishna Vukoti
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| | - Steven D. Rhodes
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| | - Kejun Cheng
- the Chemical Biology Research Branch, NIDA and NIAAA, National Institutes of Health, Bethesda, Maryland 20852
| | - Kenner C. Rice
- the Chemical Biology Research Branch, NIDA and NIAAA, National Institutes of Health, Bethesda, Maryland 20852
| | - Klaus Gawrisch
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| |
Collapse
|
27
|
Karasawa A, Erkens GB, Berntsson RPA, Otten R, Schuurman-Wolters GK, Mulder FAA, Poolman B. Cystathionine β-synthase (CBS) domains 1 and 2 fulfill different roles in ionic strength sensing of the ATP-binding cassette (ABC) transporter OpuA. J Biol Chem 2011; 286:37280-91. [PMID: 21878634 PMCID: PMC3199475 DOI: 10.1074/jbc.m111.284059] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 08/26/2011] [Indexed: 01/05/2023] Open
Abstract
The cystathionine β-synthase module of OpuA in conjunction with an anionic membrane surface acts as a sensor of internal ionic strength, which allows the protein to respond to osmotic stress. We now show by chemical modification and cross-linking studies that CBS2-CBS2 interface residues are critical for transport activity and/or ionic regulation of transport, whereas CBS1 serves no functional role. We establish that Cys residues in CBS1, CBS2, and the nucleotide-binding domain are more accessible for cross-linking at high than low ionic strength, indicating that these domains undergo conformational changes when transiting between the active and inactive state. Structural analyses suggest that the cystathionine β-synthase module is largely unstructured. Moreover, we could substitute CBS1 by a linker and preserve ionic regulation of transport. These data suggest that CBS1 serves as a linker and the structured CBS2-CBS2 interface forms a hinge point for ionic strength-dependent rearrangements that are transmitted to the nucleotide-binding domain and thereby affect translocation activity.
Collapse
Affiliation(s)
- Akira Karasawa
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Guus B. Erkens
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Ronnie P.-A. Berntsson
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Renee Otten
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Gea K. Schuurman-Wolters
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Frans A. A. Mulder
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Bert Poolman
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| |
Collapse
|
28
|
Landeta O, Landajuela A, Gil D, Taneva S, DiPrimo C, Sot B, Valle M, Frolov VA, Basañez G. Reconstitution of proapoptotic BAK function in liposomes reveals a dual role for mitochondrial lipids in the BAK-driven membrane permeabilization process. J Biol Chem 2011; 286:8213-8230. [PMID: 21196599 PMCID: PMC3048708 DOI: 10.1074/jbc.m110.165852] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 12/18/2010] [Indexed: 12/11/2022] Open
Abstract
BAK is a key effector of mitochondrial outer membrane permeabilization (MOMP) whose molecular mechanism of action remains to be fully dissected in intact cells, mainly due to the inherent complexity of the intracellular apoptotic machinery. Here we show that the core features of the BAK-driven MOMP pathway can be reproduced in a highly simplified in vitro system consisting of recombinant human BAK lacking the carboxyl-terminal 21 residues (BAKΔC) and tBID in combination with liposomes bearing an appropriate lipid environment. Using this minimalist reconstituted system we established that tBID suffices to trigger BAKΔC membrane insertion, oligomerization, and pore formation. Furthermore, we demonstrate that tBID-activated BAKΔC permeabilizes the membrane by forming structurally dynamic pores rather than a large proteinaceous channel of fixed size. We also identified two distinct roles played by mitochondrial lipids along the molecular pathway of BAKΔC-induced membrane permeabilization. First, using several independent approaches, we showed that cardiolipin directly interacts with BAKΔC, leading to a localized structural rearrangement in the protein that "primes" BAKΔC for interaction with tBID. Second, we provide evidence that selected curvature-inducing lipids present in mitochondrial membranes specifically modulate the energetic expenditure required to create the BAKΔC pore. Collectively, our results support the notion that BAK functions as a direct effector of MOMP akin to BAX and also adds significantly to the growing evidence indicating that mitochondrial membrane lipids are actively implicated in BCL-2 protein family function.
Collapse
Affiliation(s)
- Olatz Landeta
- From the Unidad de Biofísica (Centro Mixto Consejo Superior de Investigaciones Cientificas-Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - Ane Landajuela
- From the Unidad de Biofísica (Centro Mixto Consejo Superior de Investigaciones Cientificas-Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - David Gil
- CIC-BIOGUNE Structural Biology Unit, Parque Tecnologico Zamudio, Bizkaia, 48160 Derio, Spain
| | - Stefka Taneva
- From the Unidad de Biofísica (Centro Mixto Consejo Superior de Investigaciones Cientificas-Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - Carmelo DiPrimo
- Université de Bordeaux, INSERM U869, Institut Européen de Chimie et de Biologie, Pessac F-33607, France, and
| | - Begoña Sot
- the MRC Centre for Protein Engineering and MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
| | - Mikel Valle
- CIC-BIOGUNE Structural Biology Unit, Parque Tecnologico Zamudio, Bizkaia, 48160 Derio, Spain
| | - Vadim A Frolov
- From the Unidad de Biofísica (Centro Mixto Consejo Superior de Investigaciones Cientificas-Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain,; the Departamento de Bioquímica y Biología Molecular, UPV/EHU, Leioa 48940, Spain,; Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
| | - Gorka Basañez
- From the Unidad de Biofísica (Centro Mixto Consejo Superior de Investigaciones Cientificas-Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain,.
| |
Collapse
|
29
|
Abstract
The redesign of biological nanopores is focused on bacterial outer membrane proteins and pore-forming toxins, because their robust β-barrel structure makes them the best choice for developing stochastic biosensing elements. Using membrane protein engineering and single-channel electrical recordings, we explored the ferric hydroxamate uptake component A (FhuA), a monomeric 22-stranded β-barrel protein from the outer membrane of Escherichia coli. FhuA has a luminal cross-section of 3.1 × 4.4 nm and is filled by a globular N-terminal cork domain. Various redesigned FhuA proteins were investigated, including single, double, and multiple deletions of the large extracellular loops and the cork domain. We identified four large extracellular loops that partially occlude the lumen when the cork domain is removed. The newly engineered protein, FhuAΔC/Δ4L, was the result of a removal of almost one-third of the total number of amino acids of the wild-type FhuA (WT-FhuA) protein. This extensive protein engineering encompassed the entire cork domain and four extracellular loops. Remarkably, FhuAΔC/Δ4L forms a functional open pore in planar lipid bilayers, with a measured unitary conductance of ∼4.8 nanosiemens, which is much greater than the values recorded previously with other engineered FhuA protein channels. There are numerous advantages and prospects of using such an engineered outer membrane protein not only in fundamental studies of membrane protein folding and design, and the mechanisms of ion conductance and gating, but also in more applicative areas of stochastic single-molecule sensing of proteins and nucleic acids.
Collapse
Affiliation(s)
- Mohammad M Mohammad
- From the Department of Physics, Syracuse University, Syracuse, New York 13244-1130
| | - Khalil R Howard
- the Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, Syracuse, New York 13244-4100, and
| | - Liviu Movileanu
- From the Department of Physics, Syracuse University, Syracuse, New York 13244-1130,; the Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, Syracuse, New York 13244-4100, and; the Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York 13244.
| |
Collapse
|
30
|
Abstract
Bimolecular membranes are formed from two lipid monolayers at an air-water interface by the apposition of their hydrocarbon chains when an aperture in a Teflon partition separating two aqueous phases is lowered through the interface. Formation of the membrane is monitored by an increase of the electrical capacity, as measured with a voltage clamp. Electrical resistance of the unmodified membrane is analogous to that of conventional planar bilayers (black lipid membranes) prepared in the presence of a hydrocarbon solvent, i.e., 10(6)-10(8) ohm cm(2); the resistance can be lowered to values of 10(3) ohm cm(2) by gramicidin, an antibiotic that modifies the conductance only when the membranes are of biomolecular thickness. In contrast to the resistance, there is a significant difference between the capacity of bilayers made from mono-layers and that of hydrocarbon-containing bilayers made by phase transition; the average values are 0.9 and 0.45 muF cm(-2), respectively. The value of 0.9 muF cm(-2) approximates that of biological membranes. Assuming a dielectric constant of 2.1 for the hydrocarbon region, the dielectric thickness, as calculated from a capacity of 0.9 muF cm(-2), is 22 A. This value is 6-10 A smaller than the actual thickness of the hydrocarbon region of bilayers and cell membranes, as determined by x-ray diffraction. The difference may be due to a limited penetration of water into the hydrocarbon region near the ester groups that would lower the electrical resistance of this region and reduce the dielectric thickness. Asymmetric membranes have been formed by adjoining two lipid monolayers of different chemical composition.
Collapse
|