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De Maayer P, Cowan DA. Comparative genomic analysis of the flagellin glycosylation island of the Gram-positive thermophile Geobacillus. BMC Genomics 2016; 17:913. [PMID: 27842516 PMCID: PMC5109656 DOI: 10.1186/s12864-016-3273-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/05/2016] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Protein glycosylation involves the post-translational attachment of sugar chains to target proteins and has been observed in all three domains of life. Post-translational glycosylation of flagellin, the main structural protein of the flagellum, is a common characteristic among many Gram-negative bacteria and Archaea. Several distinct functions have been ascribed to flagellin glycosylation, including stabilisation and maintenance of the flagellar filament, motility, surface recognition, adhesion, and virulence. However, little is known about this trait among Gram-positive bacteria. RESULTS Using comparative genomic approaches the flagellin glycosylation loci of multiple strains of the Gram-positive thermophilic genus Geobacillus were identified and characterized. Eighteen of thirty-six compared strains of the genus carry these loci, which show evidence of horizontal acquisition. The Geobacillus flagellin glycosylation islands (FGIs) can be clustered into five distinct types, which are predicted to encode highly variable glycans decorated with distinct and heavily modified sugars. CONCLUSIONS Our comparative genomic analyses showed that, while not universal, flagellin glycosylation islands are relatively common among members of the genus Geobacillus and that the encoded flagellin glycans are highly variable. This suggests that flagellin glycosylation plays an important role in the lifestyles of members of this thermophilic genus.
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Affiliation(s)
- Pieter De Maayer
- School of Molecular and Cell Biology, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa.
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Genomics Research Institute, University of Pretoria, Pretoria, 0002, South Africa
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2
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Barhoum S, Booth V, Yethiraj A. Diffusion NMR study of complex formation in membrane-associated peptides. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2013; 42:405-14. [DOI: 10.1007/s00249-013-0890-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 01/17/2013] [Indexed: 01/12/2023]
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3
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Yeagle PL, Albert AD. Membrane protein fragments reveal both secondary and tertiary structure of membrane proteins. Methods Mol Biol 2010; 654:283-301. [PMID: 20665272 DOI: 10.1007/978-1-60761-762-4_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Structural data on membrane proteins, while crucial to understanding cellular function, are scarce due to difficulties in applying to membrane proteins the common techniques of structural biology. Fragments of membrane proteins have been shown to reflect, in many cases, the secondary structure of the parent protein with fidelity and are more amenable to study. This chapter provides many examples of how the study of membrane protein fragments has provided new insight into the structure of the parent membrane protein.
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Affiliation(s)
- Philip L Yeagle
- Office of the Dean of Arts & Sciences, Rutgers University, Newark, NJ, USA.
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4
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Bordag N, Keller S. α-Helical transmembrane peptides: A “Divide and Conquer” approach to membrane proteins. Chem Phys Lipids 2010; 163:1-26. [PMID: 19682979 DOI: 10.1016/j.chemphyslip.2009.07.009] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 07/21/2009] [Accepted: 07/21/2009] [Indexed: 11/26/2022]
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5
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Wang SSS, Tobler SA, Good TA, Fernandez EJ. Hydrogen exchange-mass spectrometry analysis of beta-amyloid peptide structure. Biochemistry 2003; 42:9507-14. [PMID: 12899638 DOI: 10.1021/bi0342766] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
beta-Amyloid peptide (A beta) is the primary protein component of senile plaques in Alzheimer's disease and is believed to be responsible for the neurodegeneration associated with the disease. A beta has proven to be toxic only when aggregated; however, the structure of the aggregated species associated with toxicity is unknown. In the present study, we use hydrogen-deuterium isotope exchange (HX)-electrospray ionization mass spectrometry (MS) along with enzymatic digestion as a tool to examine at near residue level, the changes in A beta structure associated with aggregation to a fibril form. Our results show that the structure of A beta intermediate species formed early in the course of fibrillogenesis is dependent upon solvent conditions. Additionally, the HX-MS data of peptic A beta fragments suggest that the C-terminal segment of the peptide is approximately 35% protected from exchange in fibril-containing samples, relative to monomeric A beta species prepared in DMSO/H(2)O. The N-terminus (residues 1-4) is completely unprotected from exchange, and the fragment containing residues 5-19 is over 50% protected from exchange in the fibril-containing samples. This work contributes to our understanding of A beta structure associated with aggregation and toxicity and further application of this approach may aid in the design of agents that intervene in the A beta aggregation processes associated with neurotoxicity.
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Affiliation(s)
- Steven S-S Wang
- Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA
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6
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Veglia G, Zeri AC, Ma C, Opella SJ. Deuterium/hydrogen exchange factors measured by solution nuclear magnetic resonance spectroscopy as indicators of the structure and topology of membrane proteins. Biophys J 2002; 82:2176-83. [PMID: 11916873 PMCID: PMC1302011 DOI: 10.1016/s0006-3495(02)75564-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Deuterium/hydrogen exchange factors (chi) were measured for the backbone amide sites of the membrane-bound forms of the 50-residue fd coat protein and the 23-residue magainin2 peptide in lipid micelles by solution nuclear magnetic resonance spectroscopy. By combining kinetic and thermodynamic effects, deuterium/hydrogen exchange factors overcome the principal limitations encountered in the measurements of kinetic protection factors and thermodynamic fractionation factors for membrane proteins. The magnitudes of the exchange factors can be correlated with the structure and topology of membrane-associated polypeptides. In fd coat protein, residues in the transmembrane helix have exchange factors that are substantially smaller than those in the amphipathic surface helix or the loop connecting the two helices. For the amphipathic helical peptide, magainin2, the exchange factors of residues exposed to the solvent are appreciably larger than those that face the hydrocarbon portion of membrane bilayers. These examples demonstrate that deuterium/hydrogen exchange factors can be measured by solution NMR spectroscopy and used to identify residues in transmembrane helices as well as to determine the polarity of amphipathic helices in membrane proteins.
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Affiliation(s)
- Gianluigi Veglia
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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7
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Byström T, Strandberg E, Kovacs FA, Cross TA, Lindblom G. Influence of transmembrane peptides on bilayers of phosphatidylcholines with different acyl chain lengths studied by solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1509:335-45. [PMID: 11118544 DOI: 10.1016/s0005-2736(00)00316-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The molecular orientation in a lipid membrane of the peptide fragment VEYAGIALFFVAAVLTLWSMLQYLSAAR (phosphatidylglycerophosphate synthase (Pgs) peptide E) of an integral membrane protein, Pgs, in Escherichia coli has been investigated by solid-state 15N nuclear magnetic resonance (NMR) on macroscopically aligned lipid bilayers. The secondary structure of the peptide in lipid vesicles was determined by circular dichroism spectroscopy. Furthermore, the phase behaviour of the Pgs peptide E/dierucoylphosphatidylcholine (DEruPC)/water system was determined by (2)H, (31)P and 15N solid-state NMR spectroscopy. The phase behaviour obtained was then compared to that of the Pgs peptide E solubilised in dioleoylphosphatidylcholine and water that was previously studied by Morein et al. [Biophys. J. 73 (1997) 3078-3088]. This was aimed to answer the question whether a difference in the length of the hydrophobic part of this peptide and the hydrophobic thickness of the lipid bilayer (hydrophobic mismatch) will affect the phase behaviour. The peptide mostly has a transmembrane orientation and is in an alpha-helical conformation. An isotropic phase is formed in DEruPC with high peptide content (peptide/lipid molar ratio (p/l) > or =1:15) and high water content (> or =50%, w/w) at 35 degrees C. At 55 and 65 degrees C an isotropic phase is induced at high water content (> or =50%, w/w) at all peptide contents studied (no isotropic phase forms in the lipid/water system under the conditions in this study). At high peptide contents (p/l> or =1:15) an isotropic phase forms at 20 and 40% (w/w) of water at 55 and 65 degrees C. A comparison of the phase behaviour of the two homologous lipid systems reveals striking similarities, although the thicknesses of the two lipid bilayers differ by 7 A. This suggests that the rationalisation of the phase behaviour in terms of the hydrophobic mismatch is not applicable to these systems. The C-terminus of Pgs peptide E is amphiphilic and a considerable part of the peptide is situated outside the hydrophobic part of the bilayer, a property of the peptide that to a large extent will affect the lipid/peptide phase behaviour.
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Affiliation(s)
- T Byström
- Department of Chemistry, Biophysical Chemistry, Umeå University, Sweden.
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8
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Abstract
Notwithstanding great advances in the engineering and structural analysis of globular proteins, relatively limited success has been achieved with membrane proteins--due largely to their intrinsic high insolubility and the concomitant difficulty in obtaining crystals. Progress with de novo synthesis of model membrane-interactive peptides presents an opportunity to construct simpler peptides with definable structures, and permits one to approach an understanding of the properties of the membrane proteins themselves. In the present article, we review how our laboratory and others have used peptide approaches to assess the detailed interactions of peptides with membranes, and primary folding at membrane surfaces and in membranes. Structural studies of model peptides identified the existence of a "threshold hydrophobicity," which controls spontaneous peptide insertion into membranes. Related studies of the relative helicity of peptides in organic media such as n-butanol indicate that the helical propensity of individual residues--not simply their hydrophobicity--may dictate the conformations of peptides in membranes. The overall experimental results provide fundamental guidelines for membrane protein engineering.
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Affiliation(s)
- L P Liu
- Division of Biochemistry Research, Hospital for Sick Children, Toronto, Ontario, Canada
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9
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Poulsen SA, Watson AA, Fairlie DP, Craik DJ. Solution structures in aqueous SDS micelles of two amyloid beta peptides of A beta(1-28) mutated at the alpha-secretase cleavage site (K16E, K16F). J Struct Biol 2000; 130:142-52. [PMID: 10940222 DOI: 10.1006/jsbi.2000.4267] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
NMRsolution structures are reported for two mutants (K16E, K16F) of the soluble amyloid beta peptide Abeta(1-28). The structural effects of these mutations of a positively charged residue to anionic and hydrophobic residues at the alpha-secretase cleavage site (Lys16-Leu17) were examined in the membrane-simulating solvent aqueous SDS micelles. Overall the three-dimensional structures were similar to that for the native Abeta(1-28) sequence in that they contained an unstructured N-terminus and a helical C-terminus. These structural elements are similar to those seen in the corresponding regions of full-length Abeta peptides Abeta(1-40) and Abeta(1-42), showing that the shorter peptides are valid model systems. The K16E mutation, which might be expected to stabilize the macrodipole of the helix, slightly increased the helix length (residues 13-24) relative to the K16F mutation, which shortened the helix to between residues 16 and 24. The observed sequence-dependent control over conformation in this region provides an insight into possible conformational switching roles of mutations in the amyloid precursor protein from which Abeta peptides are derived. In addition, if conformational transitions from helix to random coil to sheet precede aggregation of Abeta peptides in vivo, as they do in vitro, the conformation-inducing effects of mutations at Lys16 may also influence aggregation and fibril formation.
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Affiliation(s)
- S A Poulsen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
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10
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Anders R, Ohlenschläger O, Soskic V, Wenschuh H, Heise B, Brown LR. The NMR solution structure of the ion channel peptaibol chrysospermin C bound to dodecylphosphocholine micelles. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:1784-94. [PMID: 10712611 DOI: 10.1046/j.1432-1327.2000.01177.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chrysospermin C is a 19-residue peptaibol capable of forming transmembrane ion channels in phospholipid bilayers. The conformation of chrysospermin C bound to dodecylphosphocholine micelles has been solved using heteronuclear NMR spectroscopy. Selective 15N-labeling and 13C-labeling of specific alpha-aminoisobutyric acid residues was used to obtain complete stereospecific assignments for all eight alpha-aminoisobutyric acid residues. Structures were calculated using 339 distance constraints and 40 angle constraints obtained from NMR data. The NMR structures superimpose with mean global rmsd values to the mean structure of 0. 27 A (backbone heavy atoms) and 0.42 A (all heavy atoms). Chrysospermin C bound to decylphosphocholine micelles displays two well-defined helices at the N-terminus (residues Phe1-Aib9) and C-terminus (Aib13-Trp-ol19). A slight bend preceding Pro14, i.e. encompassing residues 10-12, results in an angle of approximately 38 degrees between the mean axes of the two helical regions. The bend structure observed for chrysospermin C is compatible with the sequences of all 18 long peptaibols and may represent a common 'active' conformation. The structure of chrysospermin C shows clear hydrophobic and hydrophilic surfaces which would be appropriate for the formation of oligomeric ion channels.
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Affiliation(s)
- R Anders
- Institut für Molekulare Biotechnologie, Jena, Germany
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11
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Czerski L, Vinogradova O, Sanders CR. NMR-Based amide hydrogen-deuterium exchange measurements for complex membrane proteins: development and critical evaluation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2000; 142:111-119. [PMID: 10617441 DOI: 10.1006/jmre.1999.1920] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A method for measuring site-specific amide hydrogen-deuterium exchange rates for membrane proteins in bilayers is reported and evaluated. This method represents an adaptation and extension of the approach of Dempsey and co-workers (Biophys. J. 70, 1777-1788 (1996)) and is based on reconstituting (15)N-labeled membrane proteins into phospholipid bilayers, followed by lyophilization and rehydration with D(2)O or H(2)O (control). Following incubation for a time t under hydrated conditions, samples are again lyophilized and then solubilized in an organic solvent system, where (1)H-(15)N HSQC spectra are recorded. Comparison of spectra from D(2)O-exposed samples to spectra from control samples yields the extent of the H-D exchange which occurred in the bilayers during time t. Measurements are site specific if specific (15)N labeling is used. The first part of this paper deals with the search for a suitable solvent system in which to solubilize complex membrane proteins in an amide "exchange-trapped" form for NMR quantitation of amide peak intensities. The second portion of the paper documents application of the overall procedure to measuring site-specific amide exchange rates in diacylglycerol kinase, a representative integral membrane protein. Both the potential usefulness and the significant limitations of the new method are documented.
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Affiliation(s)
- L Czerski
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-4970, USA
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12
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Bogen ST, de Korte-Kool G, Lindblom G, Johansson LBÅ. Aggregation of an α-Helical Transmembrane Peptide in Lipid Phases, Studied by Time-Resolved Fluorescence Spectroscopy. J Phys Chem B 1999. [DOI: 10.1021/jp9904116] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stein-Tore Bogen
- Biophysical Chemistry, Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden, and Department of Biochemistry of Membranes and Enzymology, Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Gerda de Korte-Kool
- Biophysical Chemistry, Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden, and Department of Biochemistry of Membranes and Enzymology, Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Göran Lindblom
- Biophysical Chemistry, Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden, and Department of Biochemistry of Membranes and Enzymology, Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Lennart B.-Å. Johansson
- Biophysical Chemistry, Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden, and Department of Biochemistry of Membranes and Enzymology, Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands
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13
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Rilfors L, Niemi A, Haraldsson S, Edwards K, Andersson AS, Dowhan W. Reconstituted phosphatidylserine synthase from Escherichia coli is activated by anionic phospholipids and micelle-forming amphiphiles. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1438:281-94. [PMID: 10320811 DOI: 10.1016/s1388-1981(99)00060-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The activity of phosphatidylserine (PS) synthase (CDP-1, 2-diacyl-sn-glycerol: l-serine O-phosphatidyltransferase, EC 2.7.8. 8) from Escherichia coli was studied after reconstitution with lipid vesicles of various compositions. PS synthase exhibited practically no activity in the absence of a detergent and with the substrate CDP-diacylglycerol (CDP-DAG) present only in the lipid vesicles. Inclusion of octylglucoside (OG) in the assay mixture increased the activity 20- to 1000-fold, the degree of activation depending on the lipid composition of the vesicles. Inclusion of additional CDP-DAG in the assay mixture increased the activity 5- to 25-fold. When the fraction of phosphatidylglycerol (PG) was increased from 15 to 100 mol% in the vesicles the activity increased 10-fold using the assay mixture containing OG. The highest activities were exhibited with the anionic lipids synthesized by E. coli, namely PG, diphosphatidylglycerol (DPG), and phosphatidic acid, while phosphatidylinositol gave a lower activity. Cryotransmission electron microscopy showed that transformation of the vesicles to micelles brings about an activation of the enzyme that is proportional to the degree of micellization. Thus, the activity of PS synthase is modulated by the lipid aggregate structure and by the fraction and type of anionic phospholipid in the aggregates. The increase in the activity caused by PG and DPG is physiologically relevant; it may be part of a regulatory mechanism that keeps the balance between phosphatidylethanolamine, and the sum of PG and DPG, nearly constant in wild-type E. coli cells.
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Affiliation(s)
- L Rilfors
- Department of Chemistry, Biophysical Chemistry, Umeå University, SE-901 87, Umeå, Sweden.
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14
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Soulié S, Neumann JM, Berthomieu C, Møller JV, le Maire M, Forge V. NMR conformational study of the sixth transmembrane segment of sarcoplasmic reticulum Ca2+-ATPase. Biochemistry 1999; 38:5813-21. [PMID: 10231532 DOI: 10.1021/bi983039d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In current topological models, the sarcoplasmic reticulum Ca2+-ATPase contains 10 putative transmembrane spans (M1-M10), with spans M4/M5/M6 and probably M8 participating in the formation of the membranous calcium-binding sites. We describe here the conformational properties of a synthetic peptide fragment (E785-N810) encompassing the sixth transmembrane span (M6) of Ca2+-ATPase. Peptide M6 includes three residues (N796, T799, and D800) out of the six membranous residues critically involved in the ATPase calcium-binding sites. 2D-NMR experiments were performed on the M6 peptide selectively labeled with 15N and solubilized in dodecylphosphocholine micelles to mimic a membrane-like environment. Under these conditions, M6 adopts a helical structure in its N-terminal part, between residues I788 and T799, while its C-terminal part (G801-N810) remains disordered. Addition of 20% trifluoroethanol stabilizes the alpha-helical N-terminal segment of the peptide, and reveals the propensity of the C-terminal segment (G801-L807) to form also a helix. This second helix is located at the interface or in the aqueous environment outside the micelles, while the N-terminal helix is buried in the hydrophobic core of the micelles. Furthermore, the two helical segments of M6 are linked by a flexible hinge region containing residues T799 and D800. These conformational features may be related to the transient formation of a Schellman motif (L797VTDGL802) encoded in the M6 sequence, which probably acts as a C-cap of the N-terminal helix and induces a bend with respect to the helix axis. We propose a model illustrating two conformations of M6 and its insertion in the membrane. The presence of a flexible region within M6 would greatly facilitate concomitant participation of all three residues (N796, T799, and D800) believed to be involved in calcium complexation.
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Affiliation(s)
- S Soulié
- Section de Biophysique des Protéines et des Membranes, Département de Biologie Cellulaire et Moléculaire, CEA et CNRS Unité de Recherche Associée 2096, Gif-sur-Yvette, France
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15
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Chien WJ, Cheng SF, Chang DK. Determination of the binding constant of a protein kinase C substrate, NG(28-43), to sodium dodecyl sulfate via the diffusion coefficient measured by pulsed field gradient nuclear magnetic resonance. Anal Biochem 1998; 264:211-5. [PMID: 9866685 DOI: 10.1006/abio.1998.2852] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The binding affinity of a protein kinase C substrate, neurogranin peptide NG(28-43), to a sodium dodecyl sulfate micelle was analyzed quantitatively by the diffusion coefficient (Da) of the peptide determined by pulsed field gradient NMR. By use of a two-state model, the fraction of the peptide in the bound state, and hence the binding constant, can be estimated. The obtained binding constant is within the same order of magnitude as those reported for similar systems using other techniques. The present method may be generalized to measure the formation constants of other peptide:micelle complexes.
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Affiliation(s)
- W J Chien
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China
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16
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Thermodynamic and theoretical aspects of cubic mesophases in nature and biological amphiphiles. Curr Opin Colloid Interface Sci 1998. [DOI: 10.1016/s1359-0294(98)80069-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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17
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Buchko GW, Rozek A, Hoyt DW, Cushley RJ, Kennedy MA. The use of sodium dodecyl sulfate to model the apolipoprotein environment. Evidence for peptide-SDS complexes using pulsed-field-gradient NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1392:101-8. [PMID: 9593844 DOI: 10.1016/s0005-2760(98)00028-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pulsed-field-gradient NMR spectroscopy was used to measure translational diffusion coefficients (Ds) for a peptide corresponding to a proposed lipid-binding domain of human apolipoprotein C-I, residues 7-24 (apoC-I(7-24)). Diffusion coefficients for apoC-I(7-24) were determined directly by following the decay of the resonance intensity of selected peptide protons at various concentrations of sodium dodecyl sulfate (SDS), a detergent increasingly being used to model the apolipoprotein environment. Previously, diffusion coefficients of peptides in the presence of SDS have been determined indirectly by monitoring the SDS diffusion coefficient. The direct measurement of the diffusion coefficient of the peptide enables one to distinguish whether SDS simply coats the peptide's surface to produce a uniformly charged 'rod' or if the peptide associates with a micelle. Using the direct method, at SDS concentrations above 5 mM (which is below the SDS critical micelle concentration (8.1 mM)), apoC-I(7-24) exhibited diffusion coefficients consistent with the formation of a large-molecular-weight complex. Based on the ratio of the diffusion coefficients for free- and SDS-associated peptide, the molecular weight of the peptide-SDS complex was much larger than a factor of 1. 4, the increase in molecular weight of the free peptide predicted if apoC-I(7-24) was uniformly surface coated with SDS.
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Affiliation(s)
- G W Buchko
- Pacific Northwest National Laboratories, Environmental Molecular Sciences Laboratory, Richland, WA 99352, USA
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18
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Beswick V, Roux M, Navarre C, Coïc YM, Huynh-Dinh T, Goffeau A, Sanson A, Neumann JM. 1H- and 2H-NMR studies of a fragment of PMP1, a regulatory subunit associated with the yeast plasma membrane H(+)-ATPase. Conformational properties and lipid-peptide interactions. Biochimie 1998; 80:451-9. [PMID: 9782385 DOI: 10.1016/s0300-9084(00)80012-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
PMP1 is a 38-residue polypeptide associated with the yeast plasma membrane H(+)-ATPase, found to regulate the enzyme activity. To investigate the molecular basis of the PMP1 biological function, the conformational properties of a synthetic PMP1 fragment, A18-F38, comprising the predicted C-terminal cytoplasmic domain and a part of the transmembrane anchor have been studied by 1H- and 2H-NMR spectroscopies. High resolution 1H-NMR experiments showed that, in deuterated DPC micelles, the A18-G34 segment adopts a well defined helix conformation. Our data suggest that the whole PMP1 molecule forms a unique helix whose axis might be slightly tilted with respect to the bilayer normal. Protonated DPC, DMPC and DMPS were incorporated in deuterated micelles containing the PMP1 fragment for studying lipid-peptide interactions. Unusually strong and selective intermolecular NOEs between lipid chain and peptide side chain protons, especially those of the unique Trp residue, were observed. Solid state 2H-NMR experiments performed on pure deuterated POPC and mixed deuterated POPC:POPS (5:1) bilayers revealed that the PMP1 fragment specifically interacts with negatively charged PS lipids.
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Affiliation(s)
- V Beswick
- Département de Biologie Cellulaire et Moléculaire, URA-CNRS 2096, CEA Saclay, Gif-sur-Yvette, France
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19
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Morein S, Strandberg E, Killian JA, Persson S, Arvidson G, Koeppe RE, Lindblom G. Influence of membrane-spanning alpha-helical peptides on the phase behavior of the dioleoylphosphatidylcholine/water system. Biophys J 1997; 73:3078-88. [PMID: 9414221 PMCID: PMC1181212 DOI: 10.1016/s0006-3495(97)78335-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The effect of solubilized hydrophobic peptides on the phase behavior of dioleoylphosphatidylcholine (DOPC)/water system was studied by 2H- and 31P-NMR spectroscopy and by x-ray diffraction, and partial phase diagrams were constructed. The utilized peptides were HCO-AWW(LA)5WWA-NHCH2CH2OH (WALP16), which is an artificial peptide designed to resemble a transmembrane part of a membrane protein; and VEYAGIALFFVAAVLTLWSMLQYLSAAR (Pgs peptide E), a peptide that is identical to one of the putative transmembrane segments of the membrane-associated protein phosphatidylglycerophosphate synthase (Pgs) in Escherichia coli. Circular dichroism spectroscopy suggests that both peptides are mostly alpha-helical in DOPC vesicles. The most striking features in the phase diagram of the WALP16/DOPC/water system are 1) a single lamellar liquid crystalline (L alpha) phase forms only at very low peptide concentrations. 2) At low water content and above a peptide/lipid molar ratio of approximately 1:75 a reversed hexagonal liquid crystalline (H[II]) phase coexists with an L alpha phase, while in excess water this phase forms at a peptide/lipid molar ratio of approximately 1:25. 3) At peptide/lipid ratios > or =1:6 a single H(II) phase is stable. Also, the Pgs peptide E strongly affects the phase behavior, and a single L alpha phase is only found at low peptide concentrations (peptide/lipid molar ratios <1:50), and water concentrations <45% (w/w). Higher peptide content results in coexistence of L alpha and isotropic phases. Generally, the fraction of the isotropic phase increases with increasing temperature and water concentration, and at 80% (w/w) water content only a single isotropic phase is stable at 55 degrees C. Thus, both peptides were found to be able to induce nonlamellar phases, although different in structure, in the DOPC/water system. The phase transitions, the extensions of the one-phase regions, and the phase structures observed for the two systems are discussed in terms of the molecular structure of the two peptides and the matching between the hydrophobic lengths of the peptides and the bilayer thickness of DOPC.
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Affiliation(s)
- S Morein
- Department of Physical Chemistry, Umeå University, Sweden
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