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ompX contribute to biofilm formation, osmotic response and swimming motility in Citrobacter werkmanii. Gene X 2022; 851:147019. [DOI: 10.1016/j.gene.2022.147019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/12/2022] [Accepted: 10/25/2022] [Indexed: 11/04/2022] Open
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Lee S, Mao A, Bhattacharya S, Robertson N, Grisshammer R, Tate CG, Vaidehi N. How Do Short Chain Nonionic Detergents Destabilize G-Protein-Coupled Receptors? J Am Chem Soc 2016; 138:15425-15433. [PMID: 27792324 PMCID: PMC5148649 DOI: 10.1021/jacs.6b08742] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Stability of detergent-solubilized G-protein-coupled receptors (GPCRs) is crucial for their purification in a biologically relevant state, and it is well-known that short chain detergents such as octylglucoside are more denaturing than long chain detergents such as dodecylmaltoside. However, the molecular basis for this phenomenon is poorly understood. To gain insights into the mechanism of detergent destabilization of GPCRs, we used atomistic molecular dynamics simulations of thermostabilized adenosine receptor (A2AR) mutants embedded in either a lipid bilayer or detergent micelles of alkylmaltosides and alkylglucosides. A2AR mutants in dodecylmaltoside or phospholipid showed low flexibility and good interhelical packing. In contrast, A2AR mutants in either octylglucoside or nonylglucoside showed decreased α-helicity in transmembrane regions, decreased α-helical packing, and the interpenetration of detergent molecules between transmembrane α-helices. This was not observed in octylglucoside containing phospholipid. Cholesteryl hemisuccinate in dodecylmaltoside increased the energetic stability of the receptor by wedging into crevices on the hydrophobic surface of A2AR, increasing packing interactions within the receptor and stiffening the detergent micelle. The data suggest a three-stage process for the initial events in the destabilization of GPCRs by octylglucoside: (i) highly mobile detergent molecules form small micelles around the receptor; (ii) loss of α-helicity and decreased interhelical packing interactions in transmembrane regions are promoted by increased receptor thermal motion; (iii) transient separation of transmembrane helices allowed penetration of detergent molecules into the core of the receptor. The relative hydration of the headgroup and alkyl chain correlates with detergent harshness and suggests new avenues to develop milder versions of octylglucoside for receptor crystallization.
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Affiliation(s)
- Sangbae Lee
- Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, California 91010, USA
| | - Allen Mao
- Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, California 91010, USA
| | - Supriyo Bhattacharya
- Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, California 91010, USA
| | - Nathan Robertson
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, UK
| | - Reinhard Grisshammer
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, USA
| | - Christopher G. Tate
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Nagarajan Vaidehi
- Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, California 91010, USA
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Meng X, Liu X, Zhang L, Hou B, Li B, Tan C, Li Z, Zhou R, Li S. Virulence characteristics of extraintestinal pathogenic Escherichia coli deletion of gene encoding the outer membrane protein X. J Vet Med Sci 2016; 78:1261-7. [PMID: 27149893 PMCID: PMC5053926 DOI: 10.1292/jvms.16-0071] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Outer membrane protein X (OmpX) and its homologues have been proposed to contribute to
the virulence in various bacterial species. But, their role in virulence of
extraintestinal pathogenic Escherichia coli (ExPEC) is yet to be
determined. This study evaluates the role of OmpX in ExPEC virulence in
vitro and in vivo using a clinical strain PPECC42 of porcine
origin. The ompX deletion mutant exhibited increased swimming motility
and decreased adhesion to, and invasion of pulmonary epithelial A549 cell, compared to the
wild-type strain. A mild increase in LD50 and distinct decrease in bacterial
load in such organs as heart, liver, spleen, lung and kidney were observed in mice
infected with the ompX mutant. Complementation of the complete
ompX gene in trans restored the virulence of mutant
strain to the level of wild-type strain. Our results reveal that OmpX contributes to ExPEC
virulence, but may be not an indispensable virulence determinant.
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Affiliation(s)
- Xianrong Meng
- State Key Lab of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
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Guidi HS, Henriques VB. Lattice solution model for order-disorder transitions in membranes and Langmuir monolayers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:052705. [PMID: 25493814 DOI: 10.1103/physreve.90.052705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Indexed: 06/04/2023]
Abstract
Lipid monolayers and bilayers have been used as experimental models for the investigation of membrane thermal transitions. The main transition takes place near ambient temperatures for several lipids and reflects the order-disorder transition of lipid hydrocarbonic chains, which is accompanied by a surface density gap. Equivalence between the transitions in the two systems has been argued by several authors. The two-state statistical model adopted by numerous authors for different properties of the membrane, such as permeability, diffusion, and mixture or insertion of cholesterol or protein, is inadequate for the description of charged membranes, since it lacks a proper description of surface density. We propose a lattice solution model which adds interactions with water molecules to lipid-lipid interactions and obtain its thermal properties under a mean-field approach. Density variations, although concomitant with chain order variations, are independent of the latter. The model presents both chain order and gas-liquid transitions, and extends the range of applicability of previous models, yielding Langmuir isotherms in the full range of pressures and areas.
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Affiliation(s)
- Henrique S Guidi
- Instituto de Física, Universidade de São Paulo, P.O. Box 66318, 05314-970 São Paulo, SP, Brazil and Centro de Ciências Físicas e Matemáticas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil
| | - Vera B Henriques
- Instituto de Física, Universidade de São Paulo, P.O. Box 66318, 05314-970 São Paulo, SP, Brazil
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Rouse SL, Sansom MSP. Interactions of lipids and detergents with a viral ion channel protein: molecular dynamics simulation studies. J Phys Chem B 2014; 119:764-72. [PMID: 25286030 PMCID: PMC4306293 DOI: 10.1021/jp505127y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
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Structural
studies of membrane proteins have highlighted the likely
influence of membrane mimetic environments (i.e., lipid bilayers versus
detergent micelles) on the conformation and dynamics of small α-helical
membrane proteins. We have used molecular dynamics simulations to
compare the conformational dynamics of BM2 (a small α-helical
protein from the membrane of influenza B) in a model phospholipid
bilayer environment with its behavior in protein–detergent
complexes with either the zwitterionic detergent dihexanoylphosphatidylcholine
(DHPC) or the nonionic detergent dodecylmaltoside (DDM). We find that
DDM more closely resembles the lipid bilayer in terms of its interaction
with the protein, while the short-tailed DHPC molecule forms “nonphysiological”
interactions with the protein termini. We find that the intrinsic
micelle properties of each detergent are conserved upon formation
of the protein–detergent complex. This implies that simulations
of detergent micelles may be used to help select optimal conditions
for experimental studies of membrane proteins.
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Affiliation(s)
- Sarah L Rouse
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
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Perlmutter JD, Popot JL, Sachs JN. Molecular Dynamics Simulations of a Membrane Protein/Amphipol Complex. J Membr Biol 2014; 247:883-95. [DOI: 10.1007/s00232-014-9690-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 05/22/2014] [Indexed: 12/20/2022]
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Global transcriptome analysis of Escherichia coli exposed to immobilized anthraquinone-2-sulfonate and azo dye under anaerobic conditions. Appl Microbiol Biotechnol 2013; 97:6895-905. [PMID: 23820558 DOI: 10.1007/s00253-013-5066-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 06/04/2013] [Accepted: 06/16/2013] [Indexed: 10/26/2022]
Abstract
The immobilization of quinone compounds is regarded as a promising strategy to accelerate anaerobic decolorization of xenobiotic compounds azo dyes in the presence of quinone-reducing microorganisms. However, little is known about the basic response of these microorganisms to immobilized quinones in the presence of azo dyes. In the present study, whole-genome DNA microarrays were used to investigate a quinone-reducing bacterium Escherichia coli K-12 transcription response to immobilized anthraquinone-2-sulfonate (AQSim) reduction and azo dye acid red 18 (AR 18) decolorization. Transcriptome analysis showed that AQSim was more accessible for the cells of E. coli K-12 than AR 18. Despite there being some differences between AQSim and soluble AQS mediated decolorization of AR 18, AQSim reduction and AR 18 decolorization, more similarity could be observed in the four processes. Among over 60 % shared genes, several groups of genes exhibited high expression levels, including those genes encoding terminal reductases, menaquinone biosynthesis, formate dehydrogenases and outer membrane proteins. Especially, nrfABCD, frdBCD and dsmABC encoding terminal reductases were significantly upregulated. Further gene deletion experiments demonstrated that the above three groups of genes were involved in AQSim-mediated AR 18 decolorization. In addition, significant upregulation of stress response genes was observed, which indicated the adaptation of E. coli K-12 to AQSim and AR 18 exposures.
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Neale C, Ghanei H, Holyoake J, Bishop RE, Privé GG, Pomès R. Detergent-mediated protein aggregation. Chem Phys Lipids 2013; 169:72-84. [PMID: 23466535 PMCID: PMC5007131 DOI: 10.1016/j.chemphyslip.2013.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 02/14/2013] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Abstract
Because detergents are commonly used to solvate membrane proteins for structural evaluation, much attention has been devoted to assessing the conformational bias imparted by detergent micelles in comparison to the native environment of the lipid bilayer. Here, we conduct six 500-ns simulations of a system with >600,000 atoms to investigate the spontaneous self assembly of dodecylphosphocholine detergent around multiple molecules of the integral membrane protein PagP. This detergent formed equatorial micelles in which acyl chains surround the protein's hydrophobic belt, confirming existing models of the detergent solvation of membrane proteins. In addition, unexpectedly, the extracellular and periplasmic apical surfaces of PagP interacted with the headgroups of detergents in other micelles 85 and 60% of the time, respectively, forming complexes that were stable for hundreds of nanoseconds. In some cases, an apical surface of one molecule of PagP interacted with an equatorial micelle surrounding another molecule of PagP. In other cases, the apical surfaces of two molecules of PagP simultaneously bound a neat detergent micelle. In these ways, detergents mediated the non-specific aggregation of folded PagP. These simulation results are consistent with dynamic light scattering experiments, which show that, at detergent concentrations ≥600 mM, PagP induces the formation of large scattering species that are likely to contain many copies of the PagP protein. Together, these simulation and experimental results point to a potentially generic mechanism of detergent-mediated protein aggregation.
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Affiliation(s)
- Chris Neale
- Molecular Structure and Function, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
- Department of Biochemistry, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Hamed Ghanei
- Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - John Holyoake
- Molecular Structure and Function, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
- Ontario Cancer Institute and Campbell Family Cancer Research Institute, UHN, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Russell E. Bishop
- Department of Biochemistry and Biomedical Sciences and Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Gilbert G. Privé
- Department of Biochemistry, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
- Ontario Cancer Institute and Campbell Family Cancer Research Institute, UHN, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Régis Pomès
- Molecular Structure and Function, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
- Department of Biochemistry, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
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Hagn F, Etzkorn M, Raschle T, Wagner G. Optimized phospholipid bilayer nanodiscs facilitate high-resolution structure determination of membrane proteins. J Am Chem Soc 2013; 135:1919-25. [PMID: 23294159 DOI: 10.1021/ja310901f] [Citation(s) in RCA: 391] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Structural studies of membrane proteins are still hampered by difficulties of finding appropriate membrane-mimicking media that maintain protein structure and function. Phospholipid nanodiscs seem promising to overcome the intrinsic problems of detergent-containing environments. While nanodiscs can offer a near-native environment, the large particle size complicates their routine use in the structural analysis of membrane proteins by solution NMR. Here, we introduce nanodiscs assembled from shorter ApoA-I protein variants that are of markedly smaller diameter and show that the resulting discs provide critical improvements for the structure determination of membrane proteins by NMR. Using the bacterial outer-membrane protein OmpX as an example, we demonstrate that the combination of small nanodisc size, high deuteration levels of protein and lipids, and the use of advanced non-uniform NMR sampling methods enable the NMR resonance assignment as well as the high-resolution structure determination of polytopic membrane proteins in a detergent-free, near-native lipid bilayer setting. By applying this method to bacteriorhodopsin, we show that our smaller nanodiscs can also be beneficial for the structural characterization of the important class of seven-transmembrane helical proteins. Our set of engineered nanodiscs of subsequently smaller diameters can be used to screen for optimal NMR spectral quality for small to medium-sized membrane proteins while still providing a functional environment. In addition to their key improvements for de novo structure determination, due to their smaller size these nanodiscs enable the investigation of interactions between membrane proteins and their (soluble) partner proteins, unbiased by the presence of detergents that might disrupt biologically relevant interactions.
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Affiliation(s)
- Franz Hagn
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, United States
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Abstract
Antimicrobial peptides (AMPs) provide a primordial source of immunity, conferring upon eukaryotic cells resistance against bacteria, protozoa, and viruses. Despite a few examples of anionic peptides, AMPs are usually relatively short positively charged polypeptides, consisting of a dozen to about a hundred amino acids, and exhibiting amphipathic character. Despite significant differences in their primary and secondary structures, all AMPs discovered to date share the ability to interact with cellular membranes, thereby affecting bilayer stability, disrupting membrane organization, and/or forming well-defined pores. AMPs selectively target infectious agents without being susceptible to any of the common pathways by which these acquire resistance, thereby making AMPs prime candidates to provide therapeutic alternatives to conventional drugs. However, the mechanisms of AMP actions are still a matter of intense debate. The structure-function paradigm suggests that a better understanding of how AMPs elicit their biological functions could result from atomic resolution studies of peptide-lipid interactions. In contrast, more strict thermodynamic views preclude any roles for three-dimensional structures. Indeed, the design of selective AMPs based solely on structural parameters has been challenging. In this chapter, we will focus on selected AMPs for which studies on the corresponding AMP-lipid interactions have helped reach an understanding of how AMP effects are mediated. We will emphasize the roles of both liquid- and solid-state NMR spectroscopy for elucidating the mechanisms of action of AMPs.
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Roberts CJ, Das TK, Sahin E. Predicting solution aggregation rates for therapeutic proteins: approaches and challenges. Int J Pharm 2011; 418:318-33. [PMID: 21497188 DOI: 10.1016/j.ijpharm.2011.03.064] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 03/17/2011] [Accepted: 03/24/2011] [Indexed: 01/05/2023]
Abstract
Non-native aggregation is a common concern during therapeutic protein product development and manufacturing, particularly for liquid dosage forms. Because aggregates are often net irreversible under the conditions that they form, controlling aggregate levels requires control of aggregation rates across a range of solution conditions. Rational design of product formulation(s) would therefore benefit greatly from methods to accurately predict aggregation rates. This article focuses on the principles underlying current rate-prediction approaches for non-native aggregation, the limitations and strengths of different approaches, and illustrative examples from the authors' laboratories. The analysis highlights a number of reasons why accurate prediction of aggregation rates remains an outstanding challenge, and suggests some of the important areas for research to ultimately enable improved predictive capabilities in the future.
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Affiliation(s)
- Christopher J Roberts
- Department of Chemical Engineering and Center for Molecular and Engineering Thermodynamics, University of Delaware, Newark, DE 19716, United States.
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