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Knyazev DG, Winter L, Vogt A, Posch S, Öztürk Y, Siligan C, Goessweiner-Mohr N, Hagleitner-Ertugrul N, Koch HG, Pohl P. YidC from Escherichia coli Forms an Ion-Conducting Pore upon Activation by Ribosomes. Biomolecules 2023; 13:1774. [PMID: 38136645 PMCID: PMC10741985 DOI: 10.3390/biom13121774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/01/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
The universally conserved protein YidC aids in the insertion and folding of transmembrane polypeptides. Supposedly, a charged arginine faces its hydrophobic lipid core, facilitating polypeptide sliding along YidC's surface. How the membrane barrier to other molecules may be maintained is unclear. Here, we show that the purified and reconstituted E. coli YidC forms an ion-conducting transmembrane pore upon ribosome or ribosome-nascent chain complex (RNC) binding. In contrast to monomeric YidC structures, an AlphaFold parallel YidC dimer model harbors a pore. Experimental evidence for a dimeric assembly comes from our BN-PAGE analysis of native vesicles, fluorescence correlation spectroscopy studies, single-molecule fluorescence photobleaching observations, and crosslinking experiments. In the dimeric model, the conserved arginine and other residues interacting with nascent chains point into the putative pore. This result suggests the possibility of a YidC-assisted insertion mode alternative to the insertase mechanism.
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Affiliation(s)
- Denis G. Knyazev
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
| | - Lukas Winter
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
| | - Andreas Vogt
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany (Y.Ö.); (H.-G.K.)
- Spemann-Graduate School of Biology and Medicine (SGBM), Albert Ludwig University of Freiburg, 79104 Freiburg, Germany
- Faculty of Biology, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany
| | - Sandra Posch
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
| | - Yavuz Öztürk
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany (Y.Ö.); (H.-G.K.)
| | - Christine Siligan
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
| | - Nikolaus Goessweiner-Mohr
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
| | - Nora Hagleitner-Ertugrul
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
| | - Hans-Georg Koch
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany (Y.Ö.); (H.-G.K.)
- Spemann-Graduate School of Biology and Medicine (SGBM), Albert Ludwig University of Freiburg, 79104 Freiburg, Germany
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria; (D.G.K.); (L.W.); (S.P.); (C.S.); (N.G.-M.); (N.H.-E.)
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2
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Rosetti CM, Maggio B, Oliveira RG. The self-organization of lipids and proteins of myelin at the membrane interface. Molecular factors underlying the microheterogeneity of domain segregation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1665-75. [DOI: 10.1016/j.bbamem.2008.02.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 02/08/2008] [Accepted: 02/15/2008] [Indexed: 12/12/2022]
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3
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Maggio B, Borioli GA, Del Boca M, De Tullio L, Fanani ML, Oliveira RG, Rosetti CM, Wilke N. Composition-driven surface domain structuring mediated by sphingolipids and membrane-active proteins. Above the nano- but under the micro-scale: mesoscopic biochemical/structural cross-talk in biomembranes. Cell Biochem Biophys 2007; 50:79-109. [PMID: 17968678 DOI: 10.1007/s12013-007-9004-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2007] [Indexed: 10/22/2022]
Abstract
Biomembranes contain a wide variety of lipids and proteins within an essentially two-dimensional structure. The coexistence of such a large number of molecular species causes local tensions that frequently relax into a phase or compositional immiscibility along the lateral and transverse planes of the interface. As a consequence, a substantial microheterogeneity of the surface topography develops and that depends not only on the lipid-protein composition, but also on the lateral and transverse tensions generated as a consequence of molecular interactions. The presence of proteins, and immiscibility among lipids, constitute major perturbing factors for the membrane sculpturing both in terms of its surface topography and dynamics. In this work, we will summarize some recent evidences for the involvement of membrane-associated, both extrinsic and amphitropic, proteins as well as membrane-active phosphohydrolytic enzymes and sphingolipids in driving lateral segregation of phase domains thus determining long-range surface topography.
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Affiliation(s)
- Bruno Maggio
- Departamento de Química Biológica, Facultad de Ciencias Químicas, Centro de Investigaciones en Química Biológica de Córdoba, Universidad Nacional de Córdoba - CONICET, Argentina.
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4
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Baszkin A. Molecular recognition on the supported and on the air/water interface-spread protein monolayers. Adv Colloid Interface Sci 2006; 128-130:111-20. [PMID: 17196538 DOI: 10.1016/j.cis.2006.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Targeting of proteins at interfaces via affinity ligands or specific antibodies is important for the understanding of protein functioning in biological membranes. This review brings together a great number of research works accomplished in this field in the past decade by a variety of analytical methods. It highlights two simple in situ techniques of monitoring molecular recognition processes at interfaces recently developed in the author's laboratory. The first of these techniques is based on the measurements of surface pressure increments of a protein monolayer spread at the air/water interface at a constant area resulting from the interaction with its specific ligands injected into the aqueous subphase beneath the preformed protein monolayer. The second technique takes advantage of the feature of [(14)C]-labeled proteins that enable in situ measurements of surface density changes of adsorbed protein molecules on a solid support resulting from the interaction with its specific antibody.
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Affiliation(s)
- Adam Baszkin
- Physico-Chimie des Surfaces, UMR CNRS 8612, Université Paris-Sud, 92296 Châtenay-Melabry Cedex, France.
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5
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Del Boca M, Caputto BL, Maggio B, Borioli GA. c-Jun interacts with phospholipids and c-Fos at the interface. J Colloid Interface Sci 2005; 287:80-4. [PMID: 15914151 DOI: 10.1016/j.jcis.2005.01.069] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2004] [Revised: 12/28/2004] [Accepted: 01/24/2005] [Indexed: 12/01/2022]
Abstract
We describe c-Jun, a widely studied transcription factor that participates in cell proliferation, differentiation, and tumorigenesis, as amphitropic. We show that c-Jun forms stable monolayers and interacts favorably, although in a nonselective manner, with phospholipids at the interface. The surface activity of c-Jun, together with that of c-Fos, its common partner in AP-1 transcription heterodimers, drives interfacial complex formation. We show that AP-1 is very stable at the air-water interface and suggest that AP-1 may not be substantially formed in solution as a stable equimolar association of both proteins.
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Affiliation(s)
- Maximiliano Del Boca
- CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Pabellón Argentina, Ciudad Universitaria, 5000 Córdoba, Argentina
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6
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Oliveira RG, Tanaka M, Maggio B. Many length scales surface fractality in monomolecular films of whole myelin lipids and proteins. J Struct Biol 2005; 149:158-69. [PMID: 15681232 DOI: 10.1016/j.jsb.2004.11.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Revised: 11/09/2004] [Indexed: 11/30/2022]
Abstract
Monomolecular films prepared with all the lipid and protein components of myelin were spread at the air/aqueous buffer interface from isolated bovine spinal cord myelin fully dissolved in chloroform:methanol (2:1) or by surface free energy shock of myelin membrane microvesicles. These monolayers show indistinguishable surface behavior, with similar compositional phase coexistence through all the compression isotherm on several subphase conditions. The domains were observed through epifluorescence and Brewster angle microscopy on the air/water interface and on Langmuir-Blodgett films. Their thickness was measured ellipsometrically. Under molecular packing conditions resembling those found in the natural membrane, the morphology and size of the domains are highly self-similar, displaying no characteristic length scale. These properties are the hallmark of fractal objects. The fractality extends at least three orders of magnitudes, from the micrometer to the millimeter range, the fractal dimension being about 1.7. A possible implication of fractality in membrane structure and/or function is demonstrated through the high fluctuation of the propagation of signals through constrained diffusion in corrals formed by domains in the plane of the monolayer, which restricts the diffusion of a fluorescent probe over many length scale domains.
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Affiliation(s)
- Rafael G Oliveira
- Departamento de Química Biológica-CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina
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7
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Martinet V, Saulnier P, Beaumal V, Courthaudon JL, Anton M. Surface properties of hen egg yolk low-density lipoproteins spread at the air–water interface. Colloids Surf B Biointerfaces 2003. [DOI: 10.1016/s0927-7765(03)00139-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Lavoie H, Desbat B, Vaknin D, Salesse C. Structure of rhodopsin in monolayers at the air-water interface: a PM-IRRAS and X-ray reflectivity study. Biochemistry 2002; 41:13424-34. [PMID: 12416988 DOI: 10.1021/bi026004t] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Monomolecular films of the membrane protein rhodopsin have been investigated in situ at the air-water interface by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and X-ray reflectivity in order to find conditions that retain the protein secondary structure. The spreading of rhodopsin at 0 or 5 mN m(-1) followed by a 30 min incubation time at 21 degrees C resulted in the unfolding of rhodopsin, as evidenced from the large increase of its molecular area, its small monolayer thickness, and the extensive formation of beta-sheets at the expense of the alpha-helices originally present in rhodopsin. In contrast, when spreading is performed at 5 or 10 mN m(-1) followed by an immediate compression at, respectively, 4 or 21 degrees C, the secondary structure of rhodopsin is retained, and the thickness of these films is in good agreement with the size of rhodopsin determined from its crystal structure. The amide I/amide II ratio also allowed to determine that the orientation of rhodopsin only slightly changes with surface pressure and it remains almost unchanged when the film is maintained at 20 mN m(-1) for 120 min at 4 degrees C. In addition, the PM-IRRAS spectra of rod outer segment disk membranes in monolayers suggest that rhodopsin also retained its secondary structure in these films.
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Affiliation(s)
- Hugo Lavoie
- Département de Chimie-Biologie, Université du Québec à Trois-Rivières, Québec, Canada
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9
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Maggio B, Fanani ML, Oliveira RG. Biochemical and structural information transduction at the mesoscopic level in biointerfaces containing sphingolipids. Neurochem Res 2002; 27:547-57. [PMID: 12374189 DOI: 10.1023/a:1020203512287] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this work we describe two aspects of molecular and supramolecular information transduction. The first is the biochemical and structural information content and transduction associated with sphingomyelinase activity. The results disclose a lipid-mediated cross-communication between the sphingomyelinase and phospholipase A2 pathways. In addition, the two-dimensional degradation of sphingomyelin by sphingomyelinase affects the surface topography and the latter modulates the enzyme activity. The second is the information contained in the compositionally driven lateral organization of whole glial and neuronal membrane interfaces. The myelin monolayer exhibits microheterogeneous topographical structuring and nonhomogeneous lateral thickness of phase separated regions, depending dynamically on the lateral surface pressure. On the other hand, the differential response of functional living cells depends on information contained in the molecular organization of the contacting membrane interface.
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Affiliation(s)
- Bruno Maggio
- Departamento de Química Biológica-CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Argentina.
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10
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Oliveira RG, Maggio B. Compositional domain immiscibility in whole myelin monolayers at the air-water interface and Langmuir-Blodgett films. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1561:238-50. [PMID: 11997124 DOI: 10.1016/s0005-2736(02)00350-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Monomolecular layers of whole myelin membrane can be formed at the air-water interface from vesicles or from solvent solution of myelin. The films appear microheterogeneous as seen by epifluorescence and Brewster angle microscopy. The pattern consists mainly of two coexisting liquid phases over the whole compression isotherm. The liquid nature of the phases is apparent from the fluorescent probe behavior, domain mobility, deformability and boundary relaxation due to the line tension of the surface domains. The monolayers were transferred to alkylated glass and fluorescently labeled against myelin components. The immunolabeling of two major proteins of myelin (myelin basic protein, proteolipid-DM20) and of 2',3'-cyclic nucleotide 3'-phosphodiesterase shows colocalization with probes partitioning preferentially in liquid-expanded lipid domains also containing ganglioside G(M1). A different phase showing an enrichment in cholesterol, galactocerebroside and phosphatidylserine markers is also found. The distribution of components is qualitatively independent of the lateral surface pressure and is generally constituted by one phase enriched in charged components in an expanded state coexisting with another phase enriched in non-charged constituents of lower compressibility. The domain immiscibility provides a physical basis for the microheterogeneity found in this membrane model system.
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Affiliation(s)
- Rafael G Oliveira
- Departamento de Química Biológica-CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina
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11
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Borioli GA, Caputto BL, Maggio B. c-Fos is surface active and interacts differentially with phospholipid monolayers. Biochem Biophys Res Commun 2001; 280:9-13. [PMID: 11162469 DOI: 10.1006/bbrc.2000.4081] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The transcription factor c-Fos forms stable Gibbs and Langmuir monolayers at the air-buffer interface. Its marked surface activity is enhanced by penetration into phospholipid films above the protein's own maximum adsorption surface pressure to a lipid-free interface. The protein-phospholipid stabilizing interactions at the interface depend on the lipid polar head group and the increases of lateral surface pressure generated are comparable to those of membrane-active proteins. The surface activity of c-Fos is strong enough to thermodynamically drive and retain c-Fos at the membrane interface where it may exert direct or indirect effects.
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Affiliation(s)
- G A Borioli
- Dpto. Química Biológica, CIQUIBIC, Facultad de Ciencias Químicas, Ciudad Universitaria, Pabellón Argentina, 5000 Córdoba, Argentina
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12
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Oliveira RG, Maggio B. Epifluorescence microscopy of surface domain microheterogeneity in myelin monolayers at the air-water interface. Neurochem Res 2000; 25:77-86. [PMID: 10685607 DOI: 10.1023/a:1007591516539] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Myelin lipids form liquid-expanded monolayers at the air-water interface, with no evidence of surface pressure-induced two-dimensional phase transition. However, the film doped with 2 mole % of the fluorescent probe N-(7-nitro-2-1,3-benzoxadiazol-4-yl) Diacyl Phosphatidyl-ethanolamine (NBD-PE) shows an irregular pattern of coexisting laterally segregated surface domains with diffuse boundaries that change from smooth patterns to fractal-like structures depending on surface pressure. Successive expansion-recompression cycles lead to more defined domains, with a general reorganization occurring at surface pressures of about 20 mN/m. At least two coexisting phases occur over almost all the compression isotherms. The presence of proteins in whole myelin monolayers induces defined domain textures with relatively sharp boundaries. The patterns during compression and expansion are quite similar and, after the first cycle, little changes occur under recompression. The patterns observed provide topographical evidence for the existence of dynamic domain microheterogeneity in the surface of myelin interfaces.
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Affiliation(s)
- R G Oliveira
- Departamento de Química Biológica-CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina
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13
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Oliveira RG, Calderón RO, Maggio B. Surface behavior of myelin monolayers. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1370:127-37. [PMID: 9518579 DOI: 10.1016/s0005-2736(97)00254-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Myelin can be spread as a stable monomolecular layer, with reproducible properties, at the air-water interface. The major lipids and proteins of myelin are represented in this monolayer in molar ratios similar to those in the original membrane. A well-defined collapse point of the myelin monolayer occurs at ca. 46 mN/m. At a surface pressure of ca. 20 mN/m, the surface pressure-molecular area isotherm of the myelin monolayer shows a change in its compressibility, exhibited as a diffuse but reproducible inflection with a clearly marked change of the surface compressional modulus; the surface potential-area curve shows a change of slope at the same surface pressure. The myelin monolayer shows considerable hysteresis during the first compression-decompression cycle; no detectable protein unfolding under expansion; and decreased hysteresis after the first cycle. The average molecular areas, the inflection at 20 mN/m, the variation of the surface potential per unit of molecular surface density, and the hysteresis properties of the myelin monolayer indicate that this membrane undergoes changes of intermolecular organization mostly ascribed to the protein fraction, above a lateral surface pressure of ca. 20 mN/m. The behavior is consistent with a surface pressure-dependent relocation of protein components in the film. This has marked effects on the stability, molecular packing, and dipolar organization of the myelin interface.
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Affiliation(s)
- R G Oliveira
- Departamento de Química Biológica-CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ag. Postal 4, CC 61, 5000 Córdoba, Argentina
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14
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Phase Transition Temperature of Vesicles Determined by Surface Tension Measurements: A Fast Method. J Colloid Interface Sci 1998. [DOI: 10.1006/jcis.1997.5253] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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15
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Hinterdorfer P, Gruber HJ, Striessnig J, Glossmann H, Schindler H. Analysis of membrane protein self-association in lipid systems by fluorescence particle counting: application to the dihydropyridine receptor. Biochemistry 1997; 36:4497-504. [PMID: 9109657 DOI: 10.1021/bi962009c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Fluorescence particle counting (FPC) is employed to analyze the distribution of a purified membrane protein, the dihydropyridine receptor (DHP-R), in detergent micelles, in lipid vesicles, and in lipid monolayers generated from the vesicles. The method was used to identify conditions for which DHP-Rs occur singly distributed in micelles and in vesicles. In monolayers, the DHP-R showed self-association, starting from monomeric distribution at concentrations (c) of typically 10 DHP-R/microm2. The average cluster size [m(t)] of associates was followed by FPC in time and the dependence of the lateral diffusion constant [D(lat)(m,pi)] of the associates on the surface pressure (pi) was determined. By studying the dependence of m(t) on c, pi, D(lat)(pi), and salt concentration (c(s)), we derived an empirical expression for the association rate constant (k(a)) and for m(t) that fits the experimental m(t) relations. Theoretical justification for these dependencies is obtained from collision theory, leading to a mechanistic picture of the aggregation process. DHP-R association is irreversible. Its rate is not diffusion-limited. A large number of collisions is required to overcome an interaction energy barrier of about 6-11 kT, depending on m and c(s) but not on pi. The increase in association rate with increasing average cluster size m is related to increasing van der Waals attraction, while the increase in rate with increasing c(s) relates to decreasing electrostatic repulsion. Van der Waals and electrostatic forces represent, however, only part of the interaction energy. The main contribution was not dependent on the variables studied and, most likely, reflects hydration forces which need to be overcome for association.
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16
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Nag K, Perez-Gil J, Cruz A, Rich NH, Keough KM. Spontaneous formation of interfacial lipid-protein monolayers during adsorption from vesicles. Biophys J 1996; 71:1356-63. [PMID: 8874011 PMCID: PMC1233604 DOI: 10.1016/s0006-3495(96)79338-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Spread and adsorbed monolayers of lipid-protein mixtures have served as models for biomembranes and pulmonary surfactant, but their similarity was unclear. Epifluorescence microscopy of monolayers spontaneously adsorbed from vesicles of dipalmitoylphosphatidylcholine or dipalmitoylphosphatidylcholine plus surfactant protein C (SP-C) showed gas, liquid expanded, and liquid condensed (LC) domains. The shapes and distribution of LC domains in the adsorbed and solvent-spread monolayers were quite similar. Labeled SP-C adsorbed into the air-water interface in the company of the lipids. In both forms of monolayers, SP-C occupied the fluid phase and reduced the size and amount of the LC domains. The properties suggest that these adsorbed and spread monolayers are analogous to one another.
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Affiliation(s)
- K Nag
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada
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17
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Beck K, Boswell BA, Ridgway CC, Bächinger HP. Triple helix formation of procollagen type I can occur at the rough endoplasmic reticulum membrane. J Biol Chem 1996; 271:21566-73. [PMID: 8702943 DOI: 10.1074/jbc.271.35.21566] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
One key problem in understanding the biosynthesis of collagens remains the assembly of the three alpha-chains. How and when are the different gene products selected, aligned, and folded into a triple helix? As the spatial arrangement during biosynthesis might be important, we concentrated on whether the rough endoplasmic reticular membrane is involved in this process. Microsomes were prepared from biosynthetically labeled chick tendon fibroblasts. Vesicles were spread as a monomolecular film which was then transferred over several compartments of a filmbalance containing fresh subphase. Fluorograms of the surface film showed that the monolayer contains procollagen chains. When the monolayer was transferred onto a chymotrypsin/trypsin-containing subphase, the gel bands of the proalpha-chains were shifted into the position of mature alpha-chains, indicating that only the propeptides were digested and the collagenous regions were protected due to triple helix formation. Our results suggest that newly synthesized proalpha-chains can associate as trimers and fold into a triple helical conformation while they are still associated with the membranes of the rough endoplasmic reticulum. These processes also occur when interchain disulfide linkage is inhibited, indicating that chain selection and registration is not dependent on formation of covalent bonds among the carboxyl propeptides.
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Affiliation(s)
- K Beck
- Shriners Hospital for Children, Research Unit, Portland, Oregon 97201, USA
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18
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Vassilieff CS, Panaiotov I, Manev ED, Proust JE, Ivanova T. Kinetics of liposome disintegration from foam film studies: Effect of the lipid bilayer phase state. Biophys Chem 1996; 58:97-107. [PMID: 17023351 DOI: 10.1016/0301-4622(95)00089-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/1995] [Revised: 05/22/1995] [Accepted: 05/30/1995] [Indexed: 10/18/2022]
Abstract
The kinetics of interfacial liposome breakdown is investigated in the thin liquid film microinterferometric set up of Scheludko et al. Suspensions of small unilamellar vesicles of dimyristoylphosphatidylcholine are studied at temperatures above and below the temperature of the main gel-liquid crystal first order phase transition. The experimentally established time traces of the velocity of thinning of foam films are used to estimate the kinetic (rate) constants of interfacial liposome disintegration. New and previously established data for other lipids are summarized and compared with results from kinetic measurements of lipid monolayer formation. The thin film experiments confirm the existence of interfacial liposomal aggregates. A change in the kinetic behaviour is observed, due to the 'melting' of the hydrophobic tails in the lipid aggregates. This may have various consequences of biological and pharmacological importance.
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Affiliation(s)
- C S Vassilieff
- Biophysical Chemistry Laboratory, Department of Physical Chemistry, Faculty of Chemistry, Sofia University, 1 J. Bourchiar ave, 1126 Sofia, Bulgaria
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19
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Panaiotov I, Ivanova T, Balashev K, Proust J. Spreading kinetics of dimyristoylphosphatidylcholine liposomes at the air/water interface below and above the main phase-transition temperature. Colloids Surf A Physicochem Eng Asp 1995. [DOI: 10.1016/0927-7757(95)03253-a] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Kinetics of the spreading of Intralipid™ emulsions at the air-water interface. Colloids Surf B Biointerfaces 1995. [DOI: 10.1016/0927-7765(94)01174-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Raneva V, Ivanova T, Verger R, Panaiotov I. Comparative kinetics of phospholipase A2 action on liposomes and monolayers of phosphatidylcholine spread at the air-water interface. Colloids Surf B Biointerfaces 1995. [DOI: 10.1016/0927-7765(94)01148-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Gruber HJ, Wilmsen HU, Cowell S, Schindler H, Buckley JT. Partial purification of the rat erythrocyte receptor for the channel-forming toxin aerolysin and reconstitution into planar lipid bilayers. Mol Microbiol 1994; 14:1093-101. [PMID: 7536292 DOI: 10.1111/j.1365-2958.1994.tb01341.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The cytolytic toxin aerolysin binds to a receptor on the surface of eukaryotic cells. Murine erythrocytes are among the most sensitive to the toxin. Here we describe the detergent solubilization and partial purification of the receptor from rat erythrocytes. We show that it can be successfully incorporated into planar lipid bilayers, greatly decreasing the concentration of aerolysin required to form channels. Exploiting the ability of the receptor to bind aerolysin after SDS electrophoresis and blotting, we obtain evidence that it is a 47 kDa glycoprotein that is sensitive to proteases and N-glycosidase. It may correspond to CHIP28, the water channel of the human erythrocyte.
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Affiliation(s)
- H J Gruber
- Institut für Biophysik, Johannes-Kepler-Universität Linz, Linz-Auhof, Austria
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Affiliation(s)
- R A Demel
- Department of Biochemistry of Membranes, University of Utrecht, The Netherlands
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Calderon RO, Maggio B, Neuberger TJ, De Vries GH. Surface behavior of axolemma monolayers: physico-chemical characterization and use as supported planar membranes for cultured Schwann cells. J Neurosci Res 1993; 34:206-18. [PMID: 8450564 DOI: 10.1002/jnr.490340208] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The axolemma membrane forms a stable and reproducible monomolecular layer at the air-aqueous interface. The major lipids and proteins are present in this monolayer in molar ratios similar to the original membrane. Acetylcholinesterase and Na-K-ATPase activities are preserved in the monolayer to levels of 64% and 25%, respectively. The total lipid fraction forms a homogeneously mixed phase. The presence of proteins in the monolayer introduces surface inhomogeneties. Among other features, this is revealed by the presence of two values of lateral pressure at which the monolayer shows partial or total collapse: a broad partial collapse at surface pressures between 13 to 30 mN/m and a sharp collapse point at 46 mN/m. The average molecular areas, the broad collapse point, and the variation of the surface potential per molecule suggest the relocation of protein components at surface pressures between 13 to 30 mN/m. The behavior is consistent with the extrusion and exposure of proteins toward the aqueous medium that depends on the lateral pressure. Schwann cells grown on coverslips coated with axolemma monolayers at 13 mN/m (beginning of the broad collapse) and 34 mN/m (above the broad collapse) recognize the difference in the surface organization of axolemma caused by the lateral pressure which affects their proliferation, morphology, and spatial pattern of organization. Our results show for the first time that response of Schwann cells depends on the intermolecular organization of the axolemma surface with which they interact. These results suggest that the local expression of putative surface molecules of axolemma that may mediate membrane recognition and the signalling of morphological and proliferative changes can be modulated by long range supramolecular properties.
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Affiliation(s)
- R O Calderon
- Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0614
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