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Ikujuni AP, Budiardjo SJ, Dhar R, Slusky JSG. Detergent headgroups control TolC folding in vitro. Biophys J 2023; 122:1185-1197. [PMID: 36772796 PMCID: PMC10111266 DOI: 10.1016/j.bpj.2023.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 12/29/2022] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
TolC is the trimeric outer membrane component of the efflux pump system in Escherichia coli that is responsible for antibiotic efflux from bacterial cells. Overexpression of efflux pumps has been reported to decrease susceptibility to antibiotics in a variety of bacterial pathogens. Reliable production of membrane proteins allows for the biophysical and structural characterization needed to better understand efflux and for the development of therapeutics. Preparation of recombinant protein for biochemical/structural studies often involves the production of proteins as inclusion body aggregates from which active proteins are recovered. Here, we find that the in vitro folding of TolC into its functional trimeric state from inclusion bodies is dependent on the headgroup composition of detergent micelles used. Nonionic detergent favors the formation of functional trimeric TolC, whereas zwitterionic detergents induce the formation of a non-native, oligomeric TolC fold. We also find that nonionic detergents with shorter alkyl lengths facilitate TolC folding. It remains to be seen whether the charges in lipid headgroups have similar effects on membrane insertion and folding in biological systems.
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Affiliation(s)
| | - S Jimmy Budiardjo
- Center for Computational Biology, The University of Kansas, Lawrence, Kansas
| | - Rik Dhar
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas
| | - Joanna S G Slusky
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas; Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
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2
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Zaitseva E, Obergrussberger A, Weichbrodt C, Boukhet M, Bernhard F, Hein C, Baaken G, Fertig N, Behrends JC. Electrophysiology on Channel-Forming Proteins in Artificial Lipid Bilayers: Next-Generation Instrumentation for Multiple Recordings in Parallel. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2188:67-92. [PMID: 33119847 DOI: 10.1007/978-1-0716-0818-0_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Artificial lipid bilayers have been used for several decades to study channel-forming pores and ion channels in membranes. Until recently, the classical two-chamber setups have been primarily used for studying the biophysical properties of pore forming proteins. Within the last 10 years, instruments for automated lipid bilayer measurements have been developed and are now commercially available. This chapter focuses on protein purification and reconstitution of channel-forming proteins into lipid bilayers using a classic setup and on the commercially available systems, the Orbit mini and Orbit 16.
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Affiliation(s)
| | | | | | | | - Frank Bernhard
- Institute of Biophysical Chemistry & Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Christopher Hein
- Institute of Biophysical Chemistry & Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt am Main, Germany
| | | | | | - Jan C Behrends
- Laboratory for Membrane Physiology and Technology, Department of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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3
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Schubeis T, Schwarzer TS, Le Marchand T, Stanek J, Movellan KT, Castiglione K, Pintacuda G, Andreas LB. Resonance assignment of the outer membrane protein AlkL in lipid bilayers by proton-detected solid-state NMR. BIOMOLECULAR NMR ASSIGNMENTS 2020; 14:295-300. [PMID: 32607893 DOI: 10.1007/s12104-020-09964-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
Most commonly small outer membrane proteins, possessing between 8 and 12 β-strands, are not involved in transport but fulfill diverse functions such as cell adhesion or binding of ligands. An intriguing exception are the 8-stranded β-barrel proteins of the OmpW family, which are implicated in the transport of small molecules. A representative example is AlkL from Pseudomonas putida GPoI, which functions as a passive importer of hydrophobic molecules. This role is of high interest with respect to both fundamental biological understanding and industrial applications in biocatalysis, since this protein is frequently utilized in biotransformation of alkanes. While the transport function of AlkL is generally accepted, a controversy in the transport mechanism still exists. In order to address this, we are pursuing a structural study of recombinantly produced AlkL reconstituted in lipid bilayers using solid-state NMR spectroscopy. In this manuscript we present 1H, 13C and 15N chemical shift assignments obtained via a suite of 3D experiments employing high magnetic fields (1 GHz and 800 MHz) and the latest magic-angle spinning (MAS) approaches at fast (60-111) kHz rates. We additionally analyze the secondary structure prediction in comparison with those of published structures of homologous proteins.
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Affiliation(s)
- Tobias Schubeis
- Centre de RMN à Très Hauts Champs de Lyon (FRE 2034 - CNRS, UCB Lyon 1, ENS Lyon), Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France
| | - Tom S Schwarzer
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstraße 15, 85748, Garching, Germany
| | - Tanguy Le Marchand
- Centre de RMN à Très Hauts Champs de Lyon (FRE 2034 - CNRS, UCB Lyon 1, ENS Lyon), Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France
| | - Jan Stanek
- Centre de RMN à Très Hauts Champs de Lyon (FRE 2034 - CNRS, UCB Lyon 1, ENS Lyon), Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France
| | - Kumar Tekwani Movellan
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany
| | - Kathrin Castiglione
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstraße 15, 85748, Garching, Germany
- Institute of Bioprocess Engineering, FAU Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052, Erlangen, Germany
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs de Lyon (FRE 2034 - CNRS, UCB Lyon 1, ENS Lyon), Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France.
| | - Loren B Andreas
- Centre de RMN à Très Hauts Champs de Lyon (FRE 2034 - CNRS, UCB Lyon 1, ENS Lyon), Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France.
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany.
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4
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A β-barrel for oil transport through lipid membranes: Dynamic NMR structures of AlkL. Proc Natl Acad Sci U S A 2020; 117:21014-21021. [PMID: 32817429 PMCID: PMC7474606 DOI: 10.1073/pnas.2002598117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Here we show how AlkL, a minimalistic outer-membrane protein from oil-consuming bacteria, exploits dynamics of extracellular loops to channel substrate across the polysaccharide barrier and into the hydrophobic interior of the outer membrane. This work represents a unique example of a side-by-side atomic-level structure determination by solution NMR in detergents and by solid-state NMR in lipid bilayers, which critically demonstrates the importance of a lipid environment to investigate function. Corroborating our experimental measurements, molecular-dynamics simulations capture substrate transit via lateral openings. The capacity to unravel membrane protein function under near-native conditions, fueled by the latest method developments, opens up a new frontier for their investigation, and provides thereby for improved fundamental insights into biological processes. The protein AlkL is known to increase permeability of the outer membrane of bacteria for hydrophobic molecules, yet the mechanism of transport has not been determined. Differing crystal and NMR structures of homologous proteins resulted in a controversy regarding the degree of structure and the role of long extracellular loops. Here we solve this controversy by determining the de novo NMR structure in near-native lipid bilayers, and by accessing structural dynamics relevant to hydrophobic substrate permeation through molecular-dynamics simulations and by characteristic NMR relaxation parameters. Dynamic lateral exit sites large enough to accommodate substrates such as carvone or octane occur through restructuring of a barrel extension formed by the extracellular loops.
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5
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Najbauer EE, Movellan KT, Schubeis T, Schwarzer T, Castiglione K, Giller K, Pintacuda G, Becker S, Andreas LB. Probing Membrane Protein Insertion into Lipid Bilayers by Solid-State NMR. Chemphyschem 2018; 20:302-310. [PMID: 30452110 DOI: 10.1002/cphc.201800793] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/08/2018] [Indexed: 11/09/2022]
Abstract
Determination of the environment surrounding a protein is often key to understanding its function and can also be used to infer the structural properties of the protein. By using proton-detected solid-state NMR, we show that reduced spin diffusion within the protein under conditions of fast magic-angle spinning, high magnetic field, and sample deuteration allows the efficient measurement of site-specific exposure to mobile water and lipids. We demonstrate this site specificity on two membrane proteins, the human voltage dependent anion channel, and the alkane transporter AlkL from Pseudomonas putida. Transfer from lipids is observed selectively in the membrane spanning region, and an average lipid-protein transfer rate of 6 s-1 was determined for residues protected from exchange. Transfer within the protein, as tracked in the 15 N-1 H 2D plane, was estimated from initial rates and found to be in a similar range of about 8 to 15 s-1 for several resolved residues, explaining the site specificity.
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Affiliation(s)
- Eszter E Najbauer
- Department of NMR based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Kumar Tekwani Movellan
- Department of NMR based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Tobias Schubeis
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques, UMR 5280/CNRS, ENS Lyon, UCB Lyon 1, Université de Lyon, Villeurbanne, France
| | - Tom Schwarzer
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstraße 15, D-85748, Garching, Germany
| | - Kathrin Castiglione
- Institute of Bioprocess Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 3, 91052, Erlangen, Germany
| | - Karin Giller
- Department of NMR based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques, UMR 5280/CNRS, ENS Lyon, UCB Lyon 1, Université de Lyon, Villeurbanne, France
| | - Stefan Becker
- Department of NMR based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Loren B Andreas
- Department of NMR based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
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6
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Schwarzer TS, Klermund L, Wang G, Castiglione K. Membrane functionalization of polymersomes: alleviating mass transport limitations by integrating multiple selective membrane transporters for the diffusion of chemically diverse molecules. NANOTECHNOLOGY 2018; 29:44LT01. [PMID: 30124436 DOI: 10.1088/1361-6528/aadb7e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recently, the interest in polymersomes as nanoreactors for synthetic applications has increased due to interesting proof-of-concept studies, indicating a versatile use of polymeric vesicles to compartmentalize complex reaction cascades. However, the low permeability of polymeric membranes and the requirement for a controlled mass transport across the compartment boundaries have posed a major limitation to the broad applicability of polymersomes for synthetic reactions. Current advances in the functional integration of membrane proteins (MPs) into poly(2-dimethylsiloxane)-based membranes have allowed the selective increase of the permeability for a controlled mass transport of the desired compounds across the membrane. Herein we demonstrate that polymer membranes are capable of harboring different MPs to alleviate the mass transport limitations of chemically diverse molecules, thereby enabling complex cascade reactions to be performed within the nanoreactors. The ability to functionalize the polymer membrane with multiple, highly selective MPs allows a reduction in mass transport limitations without abandoning compartmentalization of the reaction space on a low molecular mass level. As the model reaction, a two enzyme system consisting of a ketoreductase (KR) and a formate dehydrogenase was studied. For the transport of the hydrophobic substrate and product of the KR, the MPs AlkL, OmpW, OprG and TodX were investigated. For the transport of formate, OmpF, PhoE and FocA were used. AlkL showed the highest integration efficiency (39%) and a maximum of 120 AlkL molecules were successfully inserted into each polymersome. The highest channel-specific effects on the mass transfer were achieved using TodX and PhoE, respectively. The combination of both proteins led to an improvement of the space-time yield of the product (S)-pentafluorophenyl ethanol by 2.32-fold compared to nanoreactors without MPs.
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Affiliation(s)
- Tom S Schwarzer
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, D-85748 Garching, Germany
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7
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Sanganna Gari RR, Seelheim P, Marsh B, Kiessling V, Creutz CE, Tamm LK. Quaternary structure of the small amino acid transporter OprG from Pseudomonas aeruginosa. J Biol Chem 2018; 293:17267-17277. [PMID: 30237175 DOI: 10.1074/jbc.ra118.004461] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/13/2018] [Indexed: 02/01/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that causes nosocomial infections. The P. aeruginosa outer membrane contains specific porins that enable substrate uptake, with the outer membrane protein OprG facilitating transport of small, uncharged amino acids. However, the pore size of an eight-stranded β-barrel monomer of OprG is too narrow to accommodate even the smallest transported amino acid, glycine, raising the question of how OprG facilitates amino acid uptake. Pro-92 of OprG is critically important for amino acid transport, with a P92A substitution inhibiting transport and the NMR structure of this variant revealing that this substitution produces structural changes in the barrel rim and restricts loop motions. OprG may assemble into oligomers in the outer membrane (OM) whose subunit interfaces could form a transport channel. Here, we explored the contributions of the oligomeric state and the extracellular loops to OprG's function. Using chemical cross-linking to determine the oligomeric structures of both WT and P92A OprG in native outer membranes and atomic force microscopy, and single-molecule fluorescence of the purified proteins reconstituted into lipid bilayers, we found that both protein variants form oligomers, supporting the notion that subunit interfaces in the oligomer could provide a pathway for amino acid transport. Furthermore, performing transport assays with loop-deleted OprG variants, we found that these variants also can transport small amino acids, indicating that the loops are not solely responsible for substrate transport. We propose that OprG functions as an oligomer and that conformational changes in the barrel-loop region might be crucial for its activity.
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Affiliation(s)
| | - Patrick Seelheim
- From the Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology and
| | - Brendan Marsh
- the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 OWA, United Kingdom
| | - Volker Kiessling
- From the Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology and
| | - Carl E Creutz
- the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Lukas K Tamm
- From the Department of Molecular Physiology and Biological Physics, Center for Cell and Membrane Physiology and
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8
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Schubeis T, Le Marchand T, Andreas LB, Pintacuda G. 1H magic-angle spinning NMR evolves as a powerful new tool for membrane proteins. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 287:140-152. [PMID: 29413327 DOI: 10.1016/j.jmr.2017.11.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/20/2017] [Accepted: 11/22/2017] [Indexed: 06/08/2023]
Abstract
Building on a decade of continuous advances of the community, the recent development of very fast (60 kHz and above) magic-angle spinning (MAS) probes has revolutionised the field of solid-state NMR. This new spinning regime reduces the 1H-1H dipolar couplings, so that direct detection of the larger magnetic moment available from 1H is now possible at high resolution, not only in deuterated molecules but also in fully-protonated substrates. Such capabilities allow rapid "fingerprinting" of samples with a ten-fold reduction of the required sample amounts with respect to conventional approaches, and permit extensive, robust and expeditious assignment of small-to-medium sized proteins (up to ca. 300 residues), and the determination of inter-nuclear proximities, relative orientations of secondary structural elements, protein-cofactor interactions, local and global dynamics. Fast MAS and 1H detection techniques have nowadays been shown to be applicable to membrane-bound systems. This paper reviews the strategies underlying this recent leap forward in sensitivity and resolution, describing its potential for the detailed characterization of membrane proteins.
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Affiliation(s)
- Tobias Schubeis
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Tanguy Le Marchand
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Loren B Andreas
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France.
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9
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Jain MG, Lalli D, Stanek J, Gowda C, Prakash S, Schwarzer TS, Schubeis T, Castiglione K, Andreas LB, Madhu PK, Pintacuda G, Agarwal V. Selective 1H- 1H Distance Restraints in Fully Protonated Proteins by Very Fast Magic-Angle Spinning Solid-State NMR. J Phys Chem Lett 2017; 8:2399-2405. [PMID: 28492324 DOI: 10.1021/acs.jpclett.7b00983] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Very fast magic-angle spinning (MAS > 80 kHz) NMR combined with high-field magnets has enabled the acquisition of proton-detected spectra in fully protonated solid samples with sufficient resolution and sensitivity. One of the primary challenges in structure determination of protein is observing long-range 1H-1H contacts. Here we use band-selective spin-lock pulses to obtain selective 1H-1H contacts (e.g., HN-HN) on the order of 5-6 Å in fully protonated proteins at 111 kHz MAS. This approach is a major advancement in structural characterization of proteins given that magnetization can be selectively transferred between protons that are 5-6 Å apart despite the presence of other protons at shorter distance. The observed contacts are similar to those previously observed only in perdeuterated proteins with selective protonation. Simulations and experiments show the proposed method has performance that is superior to that of the currently used methods. The method is demonstrated on GB1 and a β-barrel membrane protein, AlkL.
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Affiliation(s)
- Mukul G Jain
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research , 21 Brundavan Colony, Narsingi, Hyderabad 500 075, India
| | - Daniela Lalli
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon , 5 rue de la Doua, 69100 Villeurbanne, France
| | - Jan Stanek
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon , 5 rue de la Doua, 69100 Villeurbanne, France
| | - Chandrakala Gowda
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research , 21 Brundavan Colony, Narsingi, Hyderabad 500 075, India
| | - Satya Prakash
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research , 21 Brundavan Colony, Narsingi, Hyderabad 500 075, India
| | - Tom S Schwarzer
- Institute of Biochemical Engineering, Technical University of Munich , Boltzmannstraße 15, D-85748 Garching, Germany
| | - Tobias Schubeis
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon , 5 rue de la Doua, 69100 Villeurbanne, France
| | - Kathrin Castiglione
- Institute of Biochemical Engineering, Technical University of Munich , Boltzmannstraße 15, D-85748 Garching, Germany
| | - Loren B Andreas
- Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, D-37077 Göttingen, Germany
| | - P K Madhu
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research , 21 Brundavan Colony, Narsingi, Hyderabad 500 075, India
- Department of Chemical Sciences, Tata Institute of Fundamental Research , Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon , 5 rue de la Doua, 69100 Villeurbanne, France
| | - Vipin Agarwal
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research , 21 Brundavan Colony, Narsingi, Hyderabad 500 075, India
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