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Beaud Benyahia B, Taib N, Beloin C, Gribaldo S. Terrabacteria: redefining bacterial envelope diversity, biogenesis and evolution. Nat Rev Microbiol 2024:10.1038/s41579-024-01088-0. [PMID: 39198708 DOI: 10.1038/s41579-024-01088-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2024] [Indexed: 09/01/2024]
Abstract
The bacterial envelope is one of the oldest and most essential cellular components and has been traditionally divided into Gram-positive (monoderm) and Gram-negative (diderm). Recent landmark studies have challenged a major paradigm in microbiology by inferring that the last bacterial common ancestor had a diderm envelope and that the outer membrane (OM) was lost repeatedly in evolution to give rise to monoderms. Intriguingly, OM losses appear to have occurred exclusively in the Terrabacteria, one of the two major clades of bacteria. In this Review, we present current knowledge about the Terrabacteria. We describe their diversity and phylogeny and then highlight the vast phenotypic diversity of the Terrabacteria cell envelopes, which display large deviations from the textbook examples of diderms and monoderms, challenging the classical Gram-positive-Gram-negative divide. We highlight the striking differences in the systems involved in OM biogenesis in Terrabacteria with respect to the classical diderm experimental models and how they provide novel insights into the diversity and biogenesis of the bacterial cell envelope. We also discuss the potential evolutionary steps that might have led to the multiple losses of the OM and speculate on how the very first OM might have emerged before the last bacterial common ancestor.
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Affiliation(s)
- Basile Beaud Benyahia
- Evolutionary Biology of the Microbial Cell Laboratory, Institut Pasteur, Université Paris Cité, Paris, France
| | - Najwa Taib
- Evolutionary Biology of the Microbial Cell Laboratory, Institut Pasteur, Université Paris Cité, Paris, France
- Bioinformatics and Biostatistics Hub, Institut Pasteur, Université Paris Cité, Paris, France
| | - Christophe Beloin
- Genetics of Biofilms Laboratory, Institut Pasteur, Université Paris Cité, Paris, France
| | - Simonetta Gribaldo
- Evolutionary Biology of the Microbial Cell Laboratory, Institut Pasteur, Université Paris Cité, Paris, France.
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2
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Stejskal L, Thistlethwaite A, Ramirez-Bencomo F, Rashmi S, Harrison O, Feavers IM, Maiden MCJ, Jerse A, Barnes G, Chirro O, Chemweno J, Nduati E, Cehovin A, Tang C, Sanders EJ, Derrick JP. Profiling IgG and IgA antibody responses during vaccination and infection in a high-risk gonorrhoea population. Nat Commun 2024; 15:6712. [PMID: 39112489 PMCID: PMC11306574 DOI: 10.1038/s41467-024-51053-x] [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: 11/30/2023] [Accepted: 07/29/2024] [Indexed: 08/10/2024] Open
Abstract
Development of a vaccine against gonorrhoea is a global priority, driven by the rise in antibiotic resistance. Although Neisseria gonorrhoeae (Ng) infection does not induce substantial protective immunity, highly exposed individuals may develop immunity against re-infection with the same strain. Retrospective epidemiological studies have shown that vaccines containing Neisseria meningitidis (Nm) outer membrane vesicles (OMVs) provide a degree of cross-protection against Ng infection. We conducted a clinical trial (NCT04297436) of 4CMenB (Bexsero, GSK), a licensed Nm vaccine containing OMVs and recombinant antigens, comprising a single arm, open label study of two doses with 50 adults in coastal Kenya who have high exposure to Ng. Data from a Ng antigen microarray established that serum IgG and IgA reactivities against the gonococcal homologs of the recombinant antigens in the vaccine peaked at 10 but had declined by 24 weeks. For most reactive OMV-derived antigens, the reverse was the case. A cohort of similar individuals with laboratory-confirmed gonococcal infection were compared before, during, and after infection: their reactivities were weaker and differed from the vaccinated cohort. We conclude that the cross-protection of the 4CMenB vaccine against gonorrhoea could be explained by cross-reaction against a diverse selection of antigens derived from the OMV component.
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Affiliation(s)
- Lenka Stejskal
- School of Biological Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PL, UK
| | - Angela Thistlethwaite
- School of Biological Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PL, UK
| | - Fidel Ramirez-Bencomo
- School of Biological Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PL, UK
| | - Smruti Rashmi
- School of Biological Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PL, UK
| | - Odile Harrison
- Nuffield Department of Population Health, University of Oxford, Oxford, OX3 7LF, UK
| | - Ian M Feavers
- Department of Biology, 11a Mansfield Road, University of Oxford, Oxford, OX1 3SZ, UK
| | - Martin C J Maiden
- Department of Biology, 11a Mansfield Road, University of Oxford, Oxford, OX1 3SZ, UK
| | - Ann Jerse
- Department of Microbiology and Immunology, Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Grace Barnes
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Oscar Chirro
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Eunice Nduati
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Ana Cehovin
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Christoph Tang
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
| | | | - Jeremy P Derrick
- School of Biological Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PL, UK.
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3
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Ariano K, Schweiger P. Determining the functional role of the Gluconobacter oxydans GOX1969 protein as a BamB homolog. Microbiol Spectr 2024; 12:e0106024. [PMID: 38916353 PMCID: PMC11302035 DOI: 10.1128/spectrum.01060-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 05/21/2024] [Indexed: 06/26/2024] Open
Abstract
Acetic acid bacteria are used in many industrial processes such as the production of vinegar, vitamin C, the antidiabetic drug miglitol, and various artificial flavorings. These industrially important reactions are primarily carried out by an arsenal of periplasmic-facing membrane-bound dehydrogenases that incompletely oxidize their substrates and shuttle electrons directly into the respiratory chain. Among these dehydrogenases, GOX1969 in Gluconobacter oxydans was predicted to be a pyrroloquinoline quinone-dependent dehydrogenase of unknown function. However, after multiple analysis by a number of labs, no dehydrogenase activity has been detected. Reanalysis of GOX1969 sequence and structure reveals similarities to Escherichia coli BamB, which functions as a subunit of the β-barrel assembly machinery complex that is responsible for the assembly of β-barrel outer membrane proteins in Gram-negative bacteria. To test if the physiological function of GOX1969 is similar to BamB in E. coli, we introduced the gox1969 gene into an E. coli ∆bamB mutant. Growth deficiencies in the ∆bamB mutant were restored when gox1969 was expressed on the plasmid pGox1969. Furthermore, increased membrane permeability conferred by bamB deletion was restored upon gox1969 expression, which suggests a direct link between GOX1969 and a role in maintaining outer membrane stability. Together, this evidence strongly suggests that GOX1969 is functionally acting as a BamB in G. oxydans. As such, functional information on uncharacterized genes will provide new insights that will allow for more accurate modeling of acetic acid bacterial metabolism and further efforts to design rational strains for industrial use.IMPORTANCEGluconobacter oxydans is an industrially important member of the acetic acid bacteria. Experimental characterization of putative genes is necessary to identify targets for further engineering of rational acetic acid bacteria strains that can be used in the production of vitamin C, antidiabetic compounds, artificial flavorings, or novel compounds. In this study, we have identified an undefined dehydrogenase GOX1969 with no known substrate and defined structural similarities to outer membrane biogenesis protein BamB in E. coli K12. Furthermore, we demonstrate that GOX1969 is capable of complementing bamB knockout phenotypes in E. coli K12. Taken together, these findings enhance our understanding of G. oxydans physiology and expand the list of potential targets for future industrial strain design.
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Affiliation(s)
- Ky Ariano
- Department of Microbiology, University of Wisconsin–La Crosse, La Crosse, Wisconsin, USA
| | - Paul Schweiger
- Department of Microbiology, University of Wisconsin–La Crosse, La Crosse, Wisconsin, USA
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4
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Devlin T, Fleming KG. A team of chaperones play to win in the bacterial periplasm. Trends Biochem Sci 2024; 49:667-680. [PMID: 38677921 DOI: 10.1016/j.tibs.2024.03.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/29/2024]
Abstract
The survival and virulence of Gram-negative bacteria require proper biogenesis and maintenance of the outer membrane (OM), which is densely packed with β-barrel OM proteins (OMPs). Before reaching the OM, precursor unfolded OMPs (uOMPs) must cross the whole cell envelope. A network of periplasmic chaperones and proteases maintains unfolded but folding-competent conformations of these membrane proteins in the aqueous periplasm while simultaneously preventing off-pathway aggregation. These periplasmic proteins utilize different strategies, including conformational heterogeneity, oligomerization, multivalency, and kinetic partitioning, to perform and regulate their functions. Redundant and unique characteristics of the individual periplasmic players synergize to create a protein quality control team capable responding to changing environmental stresses.
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Affiliation(s)
- Taylor Devlin
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Karen G Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
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5
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Bora JR, Mahalakshmi R. Photoradical-Mediated Catalyst-Independent Protein Cross-Link with Unusual Fluorescence Properties. Chembiochem 2023; 24:e202300380. [PMID: 37232210 PMCID: PMC7615464 DOI: 10.1002/cbic.202300380] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 05/27/2023]
Abstract
Photo-actively modified natural amino acids have served as lucrative probes for precise mapping of the dynamics, interaction networks, and turnover of cytosolic proteins both in vivo and ex vivo. In our attempts to extend the utility of photoreactive reporters to map the molecular characteristics of vital membrane proteins, we carried out site-selective incorporation of 7-fluoro-indole in the human mitochondrial outer membrane protein VDAC2 (voltage-dependent anion channel isoform 2), with the aim of generating Trp-Phe/Tyr cross-links. Prolonged irradiation at 282 nm provided us with a surprisingly unusual fluorophore that displayed sizably red-shifted excitation (λex-max =280 nm→360 nm) and emission (λem-max =330 nm→430 nm) spectra that was reversible with organic solvents. By measuring the kinetics of the photo-activated cross-linking with a library of hVDAC2 variants, we demonstrate that formation of this unusual fluorophore is kinetically retarded, independent of tryptophan, and is site-specific. Using other membrane (Tom40 and Sam50) and cytosolic (MscR and DNA Pol I) proteins, we additionally show that formation of this fluorophore is protein-independent. Our findings reveal the photoradical-mediated accumulation of reversible tyrosine cross-links, with unusual fluorescent properties. Our findings have immediate applications in protein biochemistry and UV-mediated protein aggregation and cellular damage, opening avenues for formulating therapeutics that prolong cell viability in humans.
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Affiliation(s)
- Jinam Ravindra Bora
- Molecular Biophysics Laboratory Department of Biological Sciences Indian Institute of Science Education and Research Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh (India)
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory Department of Biological Sciences Indian Institute of Science Education and Research Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh (India)
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6
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Devlin T, Fleming PJ, Loza N, Fleming KG. Generation of unfolded outer membrane protein ensembles defined by hydrodynamic properties. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:415-425. [PMID: 36899114 DOI: 10.1007/s00249-023-01639-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/23/2023] [Accepted: 02/20/2023] [Indexed: 03/12/2023]
Abstract
Outer membrane proteins (OMPs) must exist as an unfolded ensemble while interacting with a chaperone network in the periplasm of Gram-negative bacteria. Here, we developed a method to model unfolded OMP (uOMP) conformational ensembles using the experimental properties of two well-studied OMPs. The overall sizes and shapes of the unfolded ensembles in the absence of a denaturant were experimentally defined by measuring the sedimentation coefficient as a function of urea concentration. We used these data to model a full range of unfolded conformations by parameterizing a targeted coarse-grained simulation protocol. The ensemble members were further refined by short molecular dynamics simulations to reflect proper torsion angles. The final conformational ensembles have polymer properties different from unfolded soluble and intrinsically disordered proteins and reveal inherent differences in the unfolded states that necessitate further investigation. Building these uOMP ensembles advances the understanding of OMP biogenesis and provides essential information for interpreting structures of uOMP-chaperone complexes.
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Affiliation(s)
- Taylor Devlin
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Patrick J Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Nicole Loza
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Karen G Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA.
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7
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Qian M, Ismail BB, He Q, Zhang X, Yang Z, Ding T, Ye X, Liu D, Guo M. Inhibitory mechanisms of promising antimicrobials from plant byproducts: A review. Compr Rev Food Sci Food Saf 2023; 22:2523-2590. [PMID: 37070214 DOI: 10.1111/1541-4337.13152] [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: 10/31/2022] [Revised: 03/16/2023] [Accepted: 03/16/2023] [Indexed: 04/19/2023]
Abstract
Plant byproducts and waste present enormous environmental challenges and an opportunity for valorization and industrial application. Due to consumer demands for natural compounds, the evident paucity of novel antimicrobial agents against foodborne pathogens, and the urgent need to improve the arsenal against infectious diseases and antimicrobial resistance (AMR), plant byproduct compounds have attracted significant research interest. Emerging research highlighted their promising antimicrobial activity, yet the inhibitory mechanisms remain largely unexplored. Therefore, this review summarizes the overall research on the antimicrobial activity and inhibitory mechanisms of plant byproduct compounds. A total of 315 natural antimicrobials from plant byproducts, totaling 1338 minimum inhibitory concentrations (MIC) (in μg/mL) against a broad spectrum of bacteria, were identified, and a particular emphasis was given to compounds with high or good antimicrobial activity (typically <100 μg/mL MIC). Moreover, the antimicrobial mechanisms, particularly against bacterial pathogens, were discussed in-depth, summarizing the latest research on using natural compounds to combat pathogenic microorganisms and AMR. Furthermore, safety concerns, relevant legislation, consumer perspective, and current gaps in the valorization of plant byproducts-derived compounds were comprehensively discussed. This comprehensive review covering up-to-date information on antimicrobial activity and mechanisms represents a powerful tool for screening and selecting the most promising plant byproduct compounds and sources for developing novel antimicrobial agents.
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Affiliation(s)
- Mengyan Qian
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
| | - Balarabe B Ismail
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
- Department of Food Science and Technology, Bayero University Kano, Kano, Nigeria
| | - Qiao He
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
| | - Xinhui Zhang
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
| | - Zhehao Yang
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
| | - Tian Ding
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
- Fuli Institute of Food Science, Zhejiang University, Hangzhou, China
- Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Xingqian Ye
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
- Fuli Institute of Food Science, Zhejiang University, Hangzhou, China
- Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Donghong Liu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
- Fuli Institute of Food Science, Zhejiang University, Hangzhou, China
- Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Mingming Guo
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China
- Fuli Institute of Food Science, Zhejiang University, Hangzhou, China
- Ningbo Research Institute, Zhejiang University, Ningbo, China
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8
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Wijesinghe WCB, Min D. Single-Molecule Force Spectroscopy of Membrane Protein Folding. J Mol Biol 2023; 435:167975. [PMID: 37330286 DOI: 10.1016/j.jmb.2023.167975] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 06/19/2023]
Abstract
Single-molecule force spectroscopy is a unique method that can probe the structural changes of single proteins at a high spatiotemporal resolution while mechanically manipulating them over a wide force range. Here, we review the current understanding of membrane protein folding learned by using the force spectroscopy approach. Membrane protein folding in lipid bilayers is one of the most complex biological processes in which diverse lipid molecules and chaperone proteins are intricately involved. The approach of single protein forced unfolding in lipid bilayers has produced important findings and insights into membrane protein folding. This review provides an overview of the forced unfolding approach, including recent achievements and technical advances. Progress in the methods can reveal more interesting cases of membrane protein folding and clarify general mechanisms and principles.
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Affiliation(s)
- W C Bhashini Wijesinghe
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Duyoung Min
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea; Center for Wave Energy Materials, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
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9
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Zhao X, Wang LY, Tang CY, Li K, Huang YH, Duan YR, Zhang ST, Ke K, Su BH, Yang W. Electro-microenvironment modulated inhibition of endogenous biofilms by piezo implants for ultrasound-localized intestinal perforation disinfection. Biomaterials 2023; 295:122055. [PMID: 36805242 DOI: 10.1016/j.biomaterials.2023.122055] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 02/08/2023] [Accepted: 02/12/2023] [Indexed: 02/16/2023]
Abstract
Endogenous bacterial infections from damaged gastrointestinal (GI) organs have high potential to cause systemic inflammatory responses and life-threatening sepsis. Current treatments, including systemic antibiotic administration and surgical suturing, are difficult in preventing bacterial translocation and further infection. Here, we report a wireless localized stimulator composed of a piezo implant with high piezoelectric output serving as an anti-infective therapy patch, which aims at modulating the electro-microenvironment of biofilm around GI wounds for effective inhibition of bacterial infection if combined with ultrasound (US) treatment from outside the body. The pulsed charges generated by the piezo implant in response to US stimulation transfer into bacterial biofilms, effectively destroying their macromolecular components (e.g., membrane proteins), disrupting the electron transport chain of biofilms, and inhibiting bacterial proliferation, as proven by experimental studies and theoretical calculations. The piezo implant, in combination with US stimulation, also exhibits successful in vivo anti-infection efficacy in a rat cecal ligation and puncture (CLP) model. The proposed strategy, combining piezo implants with controllable US activation, creates a promising pathway for inhibiting endogenous bacterial infection caused by GI perforation.
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Affiliation(s)
- Xing Zhao
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Li-Ya Wang
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Chun-Yan Tang
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Kai Li
- Department of Thoracic Oncology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, 610041, Chengdu, China
| | - Yan-Hao Huang
- School of Materials Science and Engineering, Chongqing Jiao Tong University, Chongqing, 400074, China
| | - Yan-Ran Duan
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Shu-Ting Zhang
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Kai Ke
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, Sichuan, China.
| | - Bai-Hai Su
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Wei Yang
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, Sichuan, China.
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10
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Devlin T, Marx DC, Roskopf MA, Bubb QR, Plummer AM, Fleming KG. FkpA enhances membrane protein folding using an extensive interaction surface. Protein Sci 2023; 32:e4592. [PMID: 36775935 PMCID: PMC10031210 DOI: 10.1002/pro.4592] [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: 09/27/2022] [Revised: 01/17/2023] [Accepted: 02/07/2023] [Indexed: 02/14/2023]
Abstract
Outer membrane protein (OMP) biogenesis in gram-negative bacteria is managed by a network of periplasmic chaperones that includes SurA, Skp, and FkpA. These chaperones bind unfolded OMPs (uOMPs) in dynamic conformational ensembles to suppress aggregation, facilitate diffusion across the periplasm, and enhance folding. FkpA primarily responds to heat-shock stress, but its mechanism is comparatively understudied. To determine FkpA chaperone function in the context of OMP folding, we monitored the folding of three OMPs and found that FkpA, unlike other periplasmic chaperones, increases the folded yield but decreases the folding rate of OMPs. The results indicate that FkpA behaves as a chaperone and not as a folding catalyst to influence the OMP folding trajectory. Consistent with the folding assay results, FkpA binds all three uOMPs as determined by sedimentation velocity (SV) and photo-crosslinking experiments. We determine the binding affinity between FkpA and uOmpA171 by globally fitting SV titrations and find it to be intermediate between the known affinities of Skp and SurA for uOMP clients. Notably, complex formation steeply depends on the urea concentration, suggesting an extensive binding interface. Initial characterizations of the complex using photo-crosslinking indicate that the binding interface spans the entire FkpA molecule. In contrast to prior findings, folding and binding experiments performed using subdomain constructs of FkpA demonstrate that the full-length chaperone is required for full activity. Together these results support that FkpA has a distinct and direct effect on OMP folding that it achieves by utilizing an extensive chaperone-client interface to tightly bind clients.
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Affiliation(s)
- Taylor Devlin
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Dagan C. Marx
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Michaela A. Roskopf
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Quenton R. Bubb
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Ashlee M. Plummer
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Karen G. Fleming
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
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SurA-like and Skp-like Proteins as Important Virulence Determinants of the Gram Negative Bacterial Pathogens. Int J Mol Sci 2022; 24:ijms24010295. [PMID: 36613738 PMCID: PMC9820271 DOI: 10.3390/ijms24010295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
In the Gram-negative bacteria, many important virulence factors reach their destination via two-step export systems, and they must traverse the periplasmic space before reaching the outer membrane. Since these proteins must be maintained in a structure competent for transport into or across the membrane, they frequently require the assistance of chaperones. Based on the results obtained for the model bacterium Escherichia coli and related species, it is assumed that in the biogenesis of the outer membrane proteins and the periplasmic transit of secretory proteins, the SurA peptidyl-prolyl isomerase/chaperone plays a leading role, while the Skp chaperone is rather of secondary importance. However, detailed studies carried out on several other Gram-negative pathogens indicate that the importance of individual chaperones in the folding and transport processes depends on the properties of client proteins and is species-specific. Taking into account the importance of SurA functions in bacterial virulence and severity of phenotypes due to surA mutations, this folding factor is considered as a putative therapeutic target to combat microbial infections. In this review, we present recent findings regarding SurA and Skp proteins: their mechanisms of action, involvement in processes related to virulence, and perspectives to use them as therapeutic targets.
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12
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Wade N, Wesseling CMJ, Innocenti P, Slingerland CJ, Koningstein GM, Luirink J, Martin NI. Synthesis and Structure-Activity Studies of β-Barrel Assembly Machine Complex Inhibitor MRL-494. ACS Infect Dis 2022; 8:2242-2252. [PMID: 36318734 PMCID: PMC9673140 DOI: 10.1021/acsinfecdis.2c00459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In the hunt for new antibiotics with activity against Gram-negative pathogens, the outer membrane β-barrel assembly machine (BAM) complex has become an increasingly interesting target. The recently reported BAM complex inhibitor, MRL-494, was discovered via a screening campaign for molecules that target the outer membrane. Notably, MRL-494 was reported to be an unintended byproduct generated during the synthesis of an unrelated compound, and as such no synthesis of the compound was disclosed. We here present a convenient and reliable route for the synthesis of MRL-494 that scales well. The antibacterial activity measured for synthesized MRL-494 matches that reported in the literature. Furthermore, MRL-494 was found to exhibit potent synergistic activity with rifampicin against Gram-negative bacteria, including E. coli, K. pneumoniae, A. baumannii, and P. aeruginosa. MRL-494 was also found to cause outer membrane disruption and induction of the Rcs stress response pathway. In addition, we undertook a focused structure-activity study specifically aimed at elucidating the roles played by the two guanidine moieties contained within the structure of MRL-494.
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Affiliation(s)
- Nicola Wade
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, The Netherlands
| | - Charlotte M. J. Wesseling
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, The Netherlands
| | - Paolo Innocenti
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, The Netherlands
| | - Cornelis J. Slingerland
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, The Netherlands
| | - Gregory M. Koningstein
- Department
of Molecular Microbiology, Amsterdam Institute of Molecular and Life
Sciences (AIMMS), Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | - Joen Luirink
- Department
of Molecular Microbiology, Amsterdam Institute of Molecular and Life
Sciences (AIMMS), Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | - Nathaniel I. Martin
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, The Netherlands,
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13
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Svirina A, Chamachi N, Schlierf M. Single‐molecule approaches reveal outer membrane protein biogenesis dynamics. Bioessays 2022; 44:e2200149. [DOI: 10.1002/bies.202200149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Anna Svirina
- TU Dresden B CUBE – Center for Molecular Bioengineering Dresden Germany
| | - Neharika Chamachi
- TU Dresden B CUBE – Center for Molecular Bioengineering Dresden Germany
| | - Michael Schlierf
- TU Dresden B CUBE – Center for Molecular Bioengineering Dresden Germany
- Cluster of Excellence Physics of Life Technische Universität Dresden Dresden Germany
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14
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Ashrafi K. Better living through communal eating. Cell Host Microbe 2022; 30:1343-1344. [DOI: 10.1016/j.chom.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Characterization of Treponema denticola Major Surface Protein (Msp) by Deletion Analysis and Advanced Molecular Modeling. J Bacteriol 2022; 204:e0022822. [PMID: 35913147 PMCID: PMC9487533 DOI: 10.1128/jb.00228-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Treponema denticola, a keystone pathogen in periodontitis, is a model organism for studying Treponema physiology and host-microbe interactions. Its major surface protein Msp forms an oligomeric outer membrane complex that binds fibronectin, has cytotoxic pore-forming activity, and disrupts several intracellular processes in host cells. T. denticola msp is an ortholog of the Treponema pallidum tprA to -K gene family that includes tprK, whose remarkable in vivo hypervariability is proposed to contribute to T. pallidum immune evasion. We recently identified the primary Msp surface-exposed epitope and proposed a model of the Msp protein as a β-barrel protein similar to Gram-negative bacterial porins. Here, we report fine-scale Msp mutagenesis demonstrating that both the N and C termini as well as the centrally located Msp surface epitope are required for native Msp oligomer expression. Removal of as few as three C-terminal amino acids abrogated Msp detection on the T. denticola cell surface, and deletion of four residues resulted in complete loss of detectable Msp. Substitution of a FLAG tag for either residues 6 to 13 of mature Msp or an 8-residue portion of the central Msp surface epitope resulted in expression of full-length Msp but absence of the oligomer, suggesting roles for both domains in oligomer formation. Consistent with previously reported Msp N-glycosylation, proteinase K treatment of intact cells released a 25 kDa polypeptide containing the Msp surface epitope into culture supernatants. Molecular modeling of Msp using novel metagenome-derived multiple sequence alignment (MSA) algorithms supports the hypothesis that Msp is a large-diameter, trimeric outer membrane porin-like protein whose potential transport substrate remains to be identified. IMPORTANCE The Treponema denticola gene encoding its major surface protein (Msp) is an ortholog of the T. pallidum tprA to -K gene family that includes tprK, whose remarkable in vivo hypervariability is proposed to contribute to T. pallidum immune evasion. Using a combined strategy of fine-scale mutagenesis and advanced predictive molecular modeling, we characterized the Msp protein and present a high-confidence model of its structure as an oligomer embedded in the outer membrane. This work adds to knowledge of Msp-like proteins in oral treponemes and may contribute to understanding the evolutionary and potential functional relationships between T. denticola Msp and the orthologous T. pallidum Tpr proteins.
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16
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Chang CM, Awanye AM, Marsay L, Dold C, Pollard AJ, Rollier CS, Feavers IM, Maiden MC, Derrick JP. Application of a Neisseria meningitidis antigen microarray to identify candidate vaccine proteins from a human Phase I clinical trial. Vaccine 2022; 40:3835-3842. [DOI: 10.1016/j.vaccine.2022.05.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/04/2022] [Accepted: 05/09/2022] [Indexed: 10/18/2022]
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17
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Chaperones Skp and SurA dynamically expand unfolded OmpX and synergistically disassemble oligomeric aggregates. Proc Natl Acad Sci U S A 2022; 119:2118919119. [PMID: 35217619 PMCID: PMC8892499 DOI: 10.1073/pnas.2118919119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2022] [Indexed: 11/18/2022] Open
Abstract
Outer membrane proteins (OMPs) are crucial for the survival of bacteria. The two chaperones 17-kilodalton protein (Skp) and survival factor A (SurA) play key roles in OMP maturation by keeping unfolded OMP proteins soluble in the periplasm. However, their functionalities are incompletely understood. Here, we establish connections between structural and energetic features employed by the two chaperones when interacting with unfolded OmpX. We find that expansion, accompanied with fast polypeptide chain reconfiguration, prevents unfolded OmpX from misfolding and aggregating. Moreover, chaperone interaction with unfolded OmpX is thermodynamically calibrated, allowing for a fine-tuned association of chaperones with OMPs in the adenosine triphosphate-depleted periplasm. We further discovered that Skp and SurA act together as disaggregases and are able to disassemble oligomeric OMP aggregates, revealing remarkable functionalities of this periplasmic chaperone system. Periplasmic chaperones 17-kilodalton protein (Skp) and survival factor A (SurA) are essential players in outer membrane protein (OMP) biogenesis. They prevent unfolded OMPs from misfolding during their passage through the periplasmic space and aid in the disassembly of OMP aggregates under cellular stress conditions. However, functionally important links between interaction mechanisms, structural dynamics, and energetics that underpin both Skp and SurA associations with OMPs have remained largely unresolved. Here, using single-molecule fluorescence spectroscopy, we dissect the conformational dynamics and thermodynamics of Skp and SurA binding to unfolded OmpX and explore their disaggregase activities. We show that both chaperones expand unfolded OmpX distinctly and induce microsecond chain reconfigurations in the client OMP structure. We further reveal that Skp and SurA bind their substrate in a fine-tuned thermodynamic process via enthalpy–entropy compensation. Finally, we observed synergistic activity of both chaperones in the disaggregation of oligomeric OmpX aggregates. Our findings provide an intimate view into the multifaceted functionalities of Skp and SurA and the fine-tuned balance between conformational flexibility and underlying energetics in aiding chaperone action during OMP biogenesis.
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18
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Hermansen S, Linke D, Leo JC. Transmembrane β-barrel proteins of bacteria: From structure to function. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:113-161. [PMID: 35034717 DOI: 10.1016/bs.apcsb.2021.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The outer membrane of Gram-negative bacteria is a specialized organelle conferring protection to the cell against various environmental stresses and resistance to many harmful compounds. The outer membrane has a number of unique features, including an asymmetric lipid bilayer, the presence of lipopolysaccharides and an individual proteome. The vast majority of the integral transmembrane proteins in the outer membrane belongs to the family of β-barrel proteins. These evolutionarily related proteins share a cylindrical, anti-parallel β-sheet core fold spanning the outer membrane. The loops and accessory domains attached to the β-barrel allow for a remarkable versatility in function for these proteins, ranging from diffusion pores and transporters to enzymes and adhesins. We summarize the current knowledge on β-barrel structure and folding and give an overview of their functions, evolution, and potential as drug targets.
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Affiliation(s)
- Simen Hermansen
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Jack C Leo
- Antimicrobial resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom.
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19
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Rosas NC, Lithgow T. Targeting bacterial outer-membrane remodelling to impact antimicrobial drug resistance. Trends Microbiol 2021; 30:544-552. [PMID: 34872824 DOI: 10.1016/j.tim.2021.11.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 12/14/2022]
Abstract
The cell envelope is essential for survival and adaptation of bacteria. Bacterial membrane proteins include the major porins that mediate the influx of nutrients and several classes of antimicrobial drugs. Consequently, membrane remodelling is closely linked to antimicrobial resistance (AMR). Knowledge of bacterial membrane protein biogenesis and turnover underpins our understanding of bacterial membrane remodelling and the consequences that this process have in the evolution of AMR phenotypes. At the population level, the evolution of phenotypes is a reversible process, and we can use these insights to deploy evolutionary principles to resensitize bacteria to existing antimicrobial drugs. In our opinion, fundamental knowledge is opening a new way of thinking towards sustainable solutions to the mounting crisis in AMR. Here we discuss what is known about outer-membrane remodelling in bacteria and how the process could be targeted as a means to restore sensitivity to antimicrobial drugs. Bacteriophages are highlighted as a powerful means to exert this control over membrane remodelling but they require careful selection so as to reverse, and not exacerbate, AMR phenotypes.
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Affiliation(s)
- Natalia C Rosas
- Centre to Impact AMR, Monash University, Melbourne, Australia; Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia
| | - Trevor Lithgow
- Centre to Impact AMR, Monash University, Melbourne, Australia; Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia.
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20
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Miyazaki R, Watanabe T, Yoshitani K, Akiyama Y. Edge-strand of BepA interacts with immature LptD on the β-barrel assembly machine to direct it to on- and off-pathways. eLife 2021; 10:70541. [PMID: 34463613 PMCID: PMC8423444 DOI: 10.7554/elife.70541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/26/2021] [Indexed: 01/06/2023] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria functions as a selective permeability barrier. Escherichia coli periplasmic Zn-metallopeptidase BepA contributes to the maintenance of OM integrity through its involvement in the biogenesis and degradation of LptD, a β-barrel protein component of the lipopolysaccharide translocon. BepA either promotes the maturation of LptD when it is on the normal assembly pathway (on-pathway) or degrades it when its assembly is compromised (off-pathway). BepA performs these functions probably on the β‐barrel assembly machinery (BAM) complex. However, how BepA recognizes and directs an immature LptD to different pathways remains unclear. Here, we explored the interactions among BepA, LptD, and the BAM complex. We found that the interaction of the BepA edge-strand located adjacent to the active site with LptD was crucial not only for proteolysis but also, unexpectedly, for assembly promotion of LptD. Site-directed crosslinking analyses indicated that the unstructured N-terminal half of the β-barrel-forming domain of an immature LptD contacts with the BepA edge-strand. Furthermore, the C-terminal region of the β-barrel-forming domain of the BepA-bound LptD intermediate interacted with a ‘seam’ strand of BamA, suggesting that BepA recognized LptD assembling on the BAM complex. Our findings provide important insights into the functional mechanism of BepA.
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Affiliation(s)
- Ryoji Miyazaki
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Tetsuro Watanabe
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Kohei Yoshitani
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Yoshinori Akiyama
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
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21
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Steenhuis M, van Ulsen P, Martin NI, Luirink J. A ban on BAM: an update on inhibitors of the β-barrel assembly machinery. FEMS Microbiol Lett 2021; 368:6287571. [PMID: 34048543 DOI: 10.1093/femsle/fnab059] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 05/26/2021] [Indexed: 12/15/2022] Open
Abstract
Gram-negative pathogens are a rapidly increasing threat to human health worldwide due to high rates of antibiotic resistance and the lack of development of novel antibiotics. The protective cell envelope of gram-negative bacteria is a major permeability barrier that contributes to the problem by restricting the uptake of antibiotics. On the other hand, its unique architecture also makes it a suitable target for antibiotic interference. In particular, essential multiprotein machines that are required for biogenesis of the outer membrane have attracted attention in antibacterial design strategies. Recently, significant progress has been made in the development of inhibitors of the β-barrel assembly machine (BAM) complex. Here, we summarize the current state of drug development efforts targeting the BAM complex in pursuit of new antibiotics.
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Affiliation(s)
- Maurice Steenhuis
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Peter van Ulsen
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Nathaniel I Martin
- Biological Chemistry Group, Institute of Biology Leiden, Leiden University, Nonnensteeg 3, 2311 VJ, Leiden, The Netherlands
| | - Joen Luirink
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
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22
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Verma S, Pandey AK. Exploring Nature’s Treasure to Inhibit β-Barrel Assembly Machinery of Antibiotic Resistant Bacteria: An In silico Approach. LETT DRUG DES DISCOV 2021. [DOI: 10.2174/1570180818999201224121342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
The development of antibiotic resistance in bacteria is a matter of global
concern due to the exceptionally high morbidity and mortality rates. The outer membrane of most
gram-negative bacteria acts as a highly efficient barrier and blocks the entry of the majority of antibiotics,
making them ineffective. The Bam complex, β-barrel assembly machinery complex, contains
five subunits (BamA, B, C, D, E), which plays a vital role in folding and inserting essential
outer membrane proteins into the membrane, thus maintaining outer membrane integrity. BamA
and BamD are essential subunits to fulfill this purpose. Therefore, targeting this complex to treat
antibiotic resistance can be an incredibly effective approach. Natural bacterial pigments like
violacein, phytochemicals like withanone, semasin, and several polyphenols have often been reported
for their effective antibiotic, antioxidant, anti-inflammatory, antiviral, and anti-carcinogenic
properties.
Objective:
Structural inhibition of the Bam complex by natural compounds can provide safe and
effective treatment for antibiotic resistance by targeting outer membrane integrity.
Methods:
In-silico ADMET and molecular docking analysis was performed with ten natural compounds,
namely violacein, withanone, sesamin, resveratrol, naringenin, quercetin, epicatechin, gallic
acid, ellagic acid, and galangin, to analyse their inhibitory potential against the Bam complex.
Results:
Docking complexes of violacein gave high binding energies of -10.385 and -9.46 Kcal/mol
at C and D subunits interface and at A subunits of the Bam complex, respectively.
Conclusion:
Henceforth, violacein can be an effective antibiotic against to date reported resistant
gram-negative bacteria by inhibiting the Bam complex of their outer membrane. Therefore the urgent
need for exhaustive research in this concern is highly demanded.
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Affiliation(s)
- Shalja Verma
- Department of Biotechnology Engineering, Institute of Engineering and Technology, Bundelkhand University, Jhansi- 284128,India
| | - Anand Kumar Pandey
- Department of Biotechnology Engineering, Institute of Engineering and Technology, Bundelkhand University, Jhansi- 284128,India
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23
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Diederichs KA, Buchanan SK, Botos I. Building Better Barrels - β-barrel Biogenesis and Insertion in Bacteria and Mitochondria. J Mol Biol 2021; 433:166894. [PMID: 33639212 PMCID: PMC8292188 DOI: 10.1016/j.jmb.2021.166894] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 01/20/2023]
Abstract
β-barrel proteins are folded and inserted into outer membranes by multi-subunit protein complexes that are conserved across different types of outer membranes. In Gram-negative bacteria this complex is the barrel-assembly machinery (BAM), in mitochondria it is the sorting and assembly machinery (SAM) complex, and in chloroplasts it is the outer envelope protein Oep80. Mitochondrial β-barrel precursor proteins are translocated from the cytoplasm to the intermembrane space by the translocase of the outer membrane (TOM) complex, and stabilized by molecular chaperones before interaction with the assembly machinery. Outer membrane bacterial BamA interacts with four periplasmic accessory proteins, whereas mitochondrial Sam50 interacts with two cytoplasmic accessory proteins. Despite these major architectural differences between BAM and SAM complexes, their core proteins, BamA and Sam50, seem to function the same way. Based on the new SAM complex structures, we propose that the mitochondrial β-barrel folding mechanism follows the budding model with barrel-switching aiding in the release of new barrels. We also built a new molecular model for Tom22 interacting with Sam37 to identify regions that could mediate TOM-SAM supercomplex formation.
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Affiliation(s)
- Kathryn A Diederichs
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Susan K Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Istvan Botos
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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24
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Tiwari PB, Mahalakshmi R. Interplay of protein primary sequence, lipid membrane, and chaperone in β-barrel assembly. Protein Sci 2021; 30:624-637. [PMID: 33410567 DOI: 10.1002/pro.4022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/25/2020] [Accepted: 12/30/2020] [Indexed: 02/06/2023]
Abstract
The outer membrane of a Gram-negative bacterium is a crucial barrier between the external environment and its internal physiology. This barrier is bridged selectively by β-barrel outer membrane proteins (OMPs). The in vivo folding and biogenesis of OMPs necessitates the assistance of the outer membrane chaperone BamA. Nevertheless, OMPs retain the ability of independent self-assembly in vitro. Hence, it is unclear whether substrate-chaperone dynamics is influenced by the intrinsic ability of OMPs to fold, the magnitude of BamA-OMP interdependence, and the contribution of BamA to the kinetics of OMP assembly. We addressed this by monitoring the assembly kinetics of multiple 8-stranded β-barrel OMP substrates with(out) BamA. We also examined whether BamA is species-specific, or nonspecifically accelerates folding kinetics of substrates from independent species. Our findings reveal BamA as a substrate-independent promiscuous molecular chaperone, which assists the unfolded OMP to overcome the kinetic barrier imposed by the bilayer membrane. We additionally show that while BamA kinetically accelerates OMP folding, the OMP primary sequence remains a vital deciding element in its assembly rate. Our study provides unexpected insights on OMP assembly and the functional relevance of BamA in vivo.
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Affiliation(s)
- Pankaj B Tiwari
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
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25
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Stolle AS, Meader BT, Toska J, Mekalanos JJ. Endogenous membrane stress induces T6SS activity in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2021; 118:e2018365118. [PMID: 33443205 PMCID: PMC7817224 DOI: 10.1073/pnas.2018365118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The type 6 secretion system (T6SS) is a dynamic organelle encoded by many gram-negative bacteria that can be used to kill competing bacterial prey species in densely occupied niches. Some predatory species, such as Vibrio cholerae, use their T6SS in an untargeted fashion while in contrast, Pseudomonas aeruginosa assembles and fires its T6SS apparatus only after detecting initial attacks by other bacterial prey cells; this targeted attack strategy has been termed the T6SS tit-for-tat response. Molecules that interact with the P. aeruginosa outer membrane such as polymyxin B can also trigger assembly of T6SS organelles via a signal transduction pathway that involves protein phosphorylation. Recent work suggests that a phospholipase T6SS effector (TseL) of V. cholerae can induce T6SS dynamic activity in P. aeruginosa when delivered to or expressed in the periplasmic space of this organism. Here, we report that inhibiting expression of essential genes involved in outer membrane biogenesis can also trigger T6SS activation in P. aeruginosa Specifically, we developed a CRISPR interference (CRISPRi) system to knock down expression of bamA, tolB, and lptD and found that these knockdowns activated T6SS activity. This increase in T6SS activity was dependent on the same signal transduction pathway that was previously shown to be required for the tit-for-tat response. We conclude that outer membrane perturbation can be sensed by P. aeruginosa to activate the T6SS even when the disruption is generated by aberrant cell envelope biogenesis.
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Affiliation(s)
- Anne-Sophie Stolle
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
- Institute of Infectiology, Center for Molecular Biology of Inflammation, University of Münster, 48149 Münster, Germany
| | | | - Jonida Toska
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
| | - John J Mekalanos
- Department of Microbiology, Harvard Medical School, Boston, MA 02115;
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26
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Marx DC, Plummer AM, Faustino AM, Devlin T, Roskopf MA, Leblanc MJ, Lessen HJ, Amann BT, Fleming PJ, Krueger S, Fried SD, Fleming KG. SurA is a cryptically grooved chaperone that expands unfolded outer membrane proteins. Proc Natl Acad Sci U S A 2020; 117:28026-28035. [PMID: 33093201 PMCID: PMC7668074 DOI: 10.1073/pnas.2008175117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/26/2020] [Indexed: 11/18/2022] Open
Abstract
The periplasmic chaperone network ensures the biogenesis of bacterial outer membrane proteins (OMPs) and has recently been identified as a promising target for antibiotics. SurA is the most important member of this network, both due to its genetic interaction with the β-barrel assembly machinery complex as well as its ability to prevent unfolded OMP (uOMP) aggregation. Using only binding energy, the mechanism by which SurA carries out these two functions is not well-understood. Here, we use a combination of photo-crosslinking, mass spectrometry, solution scattering, and molecular modeling techniques to elucidate the key structural features that define how SurA solubilizes uOMPs. Our experimental data support a model in which SurA binds uOMPs in a groove formed between the core and P1 domains. This binding event results in a drastic expansion of the rest of the uOMP, which has many biological implications. Using these experimental data as restraints, we adopted an integrative modeling approach to create a sparse ensemble of models of a SurA•uOMP complex. We validated key structural features of the SurA•uOMP ensemble using independent scattering and chemical crosslinking data. Our data suggest that SurA utilizes three distinct binding modes to interact with uOMPs and that more than one SurA can bind a uOMP at a time. This work demonstrates that SurA operates in a distinct fashion compared to other chaperones in the OMP biogenesis network.
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Affiliation(s)
- Dagan C Marx
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Ashlee M Plummer
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | | | - Taylor Devlin
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Michaela A Roskopf
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Mathis J Leblanc
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Henry J Lessen
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Barbara T Amann
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Patrick J Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Susan Krueger
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Stephen D Fried
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218
| | - Karen G Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218;
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Reversible autoinhibitory regulation of Escherichia coli metallopeptidase BepA for selective β-barrel protein degradation. Proc Natl Acad Sci U S A 2020; 117:27989-27996. [PMID: 33093205 DOI: 10.1073/pnas.2010301117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Escherichia coli periplasmic zinc-metallopeptidase BepA normally functions by promoting maturation of LptD, a β-barrel outer-membrane protein involved in biogenesis of lipopolysaccharides, but degrades it when its membrane assembly is hampered. These processes should be properly regulated to ensure normal biogenesis of LptD. The underlying mechanism of regulation, however, remains to be elucidated. A recently solved BepA structure has revealed unique features: In particular, the active site is buried in the protease domain and conceivably inaccessible for substrate degradation. Additionally, the His-246 residue in the loop region containing helix α9 (α9/H246 loop), which has potential flexibility and covers the active site, coordinates the zinc ion as the fourth ligand to exclude a catalytic water molecule, thereby suggesting that the crystal structure of BepA represents a latent form. To examine the roles of the α9/H246 loop in the regulation of BepA activity, we constructed BepA mutants with a His-246 mutation or a deletion of the α9/H246 loop and analyzed their activities in vivo and in vitro. These mutants exhibited an elevated protease activity and, unlike the wild-type BepA, degraded LptD that is in the normal assembly pathway. In contrast, tethering of the α9/H246 loop repressed the LptD degradation, which suggests that the flexibility of this loop is important to the exhibition of protease activity. Based on these results, we propose that the α9/H246 loop undergoes a reversible structural change that enables His-246-mediated switching (histidine switch) of its protease activity, which is important for regulated degradation of stalled/misassembled LptD.
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Marx DC, Leblanc MJ, Plummer AM, Krueger S, Fleming KG. Domain interactions determine the conformational ensemble of the periplasmic chaperone SurA. Protein Sci 2020; 29:2043-2053. [PMID: 32748422 PMCID: PMC7513704 DOI: 10.1002/pro.3924] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 12/17/2022]
Abstract
SurA is thought to be the most important periplasmic chaperone for outer membrane protein (OMP) biogenesis. Its structure is composed of a core region and two peptidylprolyl isomerase domains, termed P1 and P2, connected by flexible linkers. As such these three independent folding units are able to adopt a number of distinct spatial positions with respect to each other. The conformational dynamics of these domains are thought to be functionally important yet are largely unresolved. Here we address this question of the conformational ensemble using sedimentation equilibrium, small-angle neutron scattering, and folding titrations. This combination of orthogonal methods converges on a SurA population that is monomeric at physiological concentrations. The conformation that dominates this population has the P1 and core domains docked to one another, for example, "P1-closed" and the P2 domain extended in solution. We discovered that the distribution of domain orientations is defined by modest and favorable interactions between the core domain and either the P1 or the P2 domains. These two peptidylprolyl domains compete with each other for core-binding but are thermodynamically uncoupled. This arrangement implies two novel insights. Firstly, an open conformation must exist to facilitate P1 and P2 exchange on the core, indicating that the open client-binding conformation is populated at low levels even in the absence of client unfolded OMPs. Secondly, competition between P1 and P2 binding paradoxically occludes the client binding site on the core, which may serve to preserve the reservoir of binding-competent apo-SurA in the periplasm.
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Affiliation(s)
- Dagan C. Marx
- Thomas C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Mathis J. Leblanc
- Thomas C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Ashlee M. Plummer
- Thomas C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
- Department of Cell BiologyHarvard Medical SchoolBostonMassachusettsUSA
| | - Susan Krueger
- National Institute of Standards and TechnologyGaithersburgMarylandUSA
| | - Karen G. Fleming
- Thomas C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
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SecY-mediated quality control prevents the translocation of non-gated porins. Sci Rep 2020; 10:16347. [PMID: 33004891 PMCID: PMC7530735 DOI: 10.1038/s41598-020-73185-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 09/09/2020] [Indexed: 01/24/2023] Open
Abstract
OmpC and OmpF are among the most abundant outer membrane proteins in E. coli and serve as hydrophilic channels to mediate uptake of small molecules including antibiotics. Influx selectivity is controlled by the so-called constriction zone or eyelet of the channel. Mutations in the loop domain forming the eyelet can disrupt transport selectivity and thereby interfere with bacterial viability. In this study we show that a highly conserved motif of five negatively charged amino acids in the eyelet, which is critical to regulate pore selectivity, is also required for SecY-mediated transport of OmpC and OmpF into the periplasm. Variants with a deleted or mutated motif were expressed in the cytosol and translocation was initiated. However, after signal peptide cleavage, import into the periplasm was aborted and the mutated proteins were redirected to the cytosol. Strikingly, reducing the proof-reading capacity of SecY by introducing the PrlA4 substitutions restored transport of OmpC with a mutated channel domain into the periplasm. Our study identified a SecY-mediated quality control pathway to restrict transport of outer membrane porin proteins with a deregulated channel activity into the periplasm.
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30
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Affinity of Skp to OmpC revealed by single-molecule detection. Sci Rep 2020; 10:14871. [PMID: 32913243 PMCID: PMC7483523 DOI: 10.1038/s41598-020-71608-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 08/19/2020] [Indexed: 11/09/2022] Open
Abstract
Outer membrane proteins (OMPs) are essential to gram-negative bacteria, and molecular chaperones prevent the OMPs from aggregation in the periplasm during the OMPs biogenesis. Skp is one of the molecular chaperones for this purpose. Here, we combined single-molecule fluorescence resonance energy transfer and fluorescence correlation spectroscopy to study the affinity and stoichiometric ratio of Skp in its binding with OmpC at the single-molecule level. The half concentration of the Skp self-trimerization (C1/2) was measured to be (2.5 ± 0.7) × 102 nM. Under an Skp concentration far below the C1/2, OmpC could recruit Skp monomers to form OmpC·Skp3. The affinity to form the OmpC·Skp3 complex was determined to be (5.5 ± 0.4) × 102 pM with a Hill coefficient of 1.6 ± 0.2. Under the micromolar concentrations of Skp, the formation of OmpC·(Skp3)2 was confirmed, and the dissociation constant of OmpC·(Skp3)2 was determined to be 1.2 ± 0.4 μM. The precise information will help us to quantitatively depict the role of Skp in the biogenesis of OMPs.
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31
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Ding Y, Shiota T, Le Brun AP, Dunstan RA, Wang B, Hsu HY, Lithgow T, Shen HH. Characterization of BamA reconstituted into a solid-supported lipid bilayer as a platform for measuring dynamics during substrate protein assembly into the membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183317. [DOI: 10.1016/j.bbamem.2020.183317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/14/2022]
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Cao P, Wall D. The Fluidity of the Bacterial Outer Membrane Is Species Specific: Bacterial Lifestyles and the Emergence of a Fluid Outer Membrane. Bioessays 2020; 42:e1900246. [PMID: 32363627 PMCID: PMC7392792 DOI: 10.1002/bies.201900246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/23/2020] [Indexed: 01/17/2023]
Abstract
The outer membrane (OM) is an essential barrier that guards Gram-negative bacteria from diverse environmental insults. Besides functioning as a chemical gatekeeper, the OM also contributes towards the strength and stiffness of cells and allows them to sustain mechanical stress. Largely influenced by studies of Escherichia coli, the OM is viewed as a rigid barrier where OM proteins and lipopolysaccharides display restricted mobility. Here the discussion is extended to other bacterial species, with a focus on Myxococcus xanthus. In contrast to the rigid OM paradigm, myxobacteria possess a relatively fluid OM. It is concluded that the fluidity of the OM varies across environmental species, which is likely linked to their evolution and adaptation to specific ecological niches. Importantly, a fluid OM can endow bacteria with distinct functions for cell-cell and cell-environment interactions.
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Affiliation(s)
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, 1000 E University Avenue, Laramie, WY, 82071, USA
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33
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Wu X, Siggel M, Ovchinnikov S, Mi W, Svetlov V, Nudler E, Liao M, Hummer G, Rapoport TA. Structural basis of ER-associated protein degradation mediated by the Hrd1 ubiquitin ligase complex. Science 2020; 368:368/6489/eaaz2449. [PMID: 32327568 DOI: 10.1126/science.aaz2449] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 01/18/2020] [Accepted: 03/11/2020] [Indexed: 12/13/2022]
Abstract
Misfolded luminal endoplasmic reticulum (ER) proteins undergo ER-associated degradation (ERAD-L): They are retrotranslocated into the cytosol, polyubiquitinated, and degraded by the proteasome. ERAD-L is mediated by the Hrd1 complex (composed of Hrd1, Hrd3, Der1, Usa1, and Yos9), but the mechanism of retrotranslocation remains mysterious. Here, we report a structure of the active Hrd1 complex, as determined by cryo-electron microscopy analysis of two subcomplexes. Hrd3 and Yos9 jointly create a luminal binding site that recognizes glycosylated substrates. Hrd1 and the rhomboid-like Der1 protein form two "half-channels" with cytosolic and luminal cavities, respectively, and lateral gates facing one another in a thinned membrane region. These structures, along with crosslinking and molecular dynamics simulation results, suggest how a polypeptide loop of an ERAD-L substrate moves through the ER membrane.
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Affiliation(s)
- Xudong Wu
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Marc Siggel
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Sergey Ovchinnikov
- Faculty of Arts and Sciences, Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Wei Mi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.,Present address: Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Vladimir Svetlov
- Howard Hughes Medical Institute and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Evgeny Nudler
- Howard Hughes Medical Institute and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.,Institute of Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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34
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Hu Y, Li C, He L, Jin C, Liu M. Mechanisms of Chaperones as Active Assistant/Protector for Proteins: Insights from NMR Studies. CHINESE J CHEM 2020. [DOI: 10.1002/cjoc.201900441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yunfei Hu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Conggang Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Lichun He
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, College of Life Sciences, Peking University Beijing 100871 China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
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35
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Ryoo D, Rydmark MO, Pang YT, Lundquist KP, Linke D, Gumbart JC. BamA is required for autotransporter secretion. Biochim Biophys Acta Gen Subj 2020; 1864:129581. [PMID: 32114025 DOI: 10.1016/j.bbagen.2020.129581] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 02/01/2020] [Accepted: 02/22/2020] [Indexed: 01/24/2023]
Abstract
BACKGROUND In Gram-negative bacteria, type Va and Vc autotransporters are proteins that contain both a secreted virulence factor (the "passenger" domain) and a β-barrel that aids its export. While it is known that the folding and insertion of the β-barrel domain utilize the β-barrel assembly machinery (BAM) complex, how the passenger domain is secreted and folded across the membrane remains to be determined. The hairpin model states that passenger domain secretion occurs independently through the fully-formed and membrane-inserted β-barrel domain via a hairpin folding intermediate. In contrast, the BamA-assisted model states that the passenger domain is secreted through a hybrid of BamA, the essential subunit of the BAM complex, and the β-barrel domain of the autotransporter. METHODS To ascertain the models' plausibility, we have used molecular dynamics to simulate passenger domain secretion for two autotransporters, EspP and YadA. RESULTS We observed that each protein's β-barrel is unable to accommodate the secreting passenger domain in a hairpin configuration without major structural distortions. Additionally, the force required for secretion through EspP's β-barrel is more than that through the BamA β-barrel. CONCLUSIONS Secretion of autotransporters most likely occurs through an incompletely formed β-barrel domain of the autotransporter in conjunction with BamA. GENERAL SIGNIFICANCE Secretion of virulence factors is a process used by practically all pathogenic Gram-negative bacteria. Understanding this process is a necessary step towards limiting their infectious capacity.
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Affiliation(s)
- David Ryoo
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332, United States of America
| | | | - Yui Tik Pang
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30313, United States of America
| | - Karl P Lundquist
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, United States of America
| | - Dirk Linke
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30313, United States of America.
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36
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Gunasinghe SD, Shiota T, Stubenrauch CJ, Schulze KE, Webb CT, Fulcher AJ, Dunstan RA, Hay ID, Naderer T, Whelan DR, Bell TDM, Elgass KD, Strugnell RA, Lithgow T. The WD40 Protein BamB Mediates Coupling of BAM Complexes into Assembly Precincts in the Bacterial Outer Membrane. Cell Rep 2019; 23:2782-2794. [PMID: 29847806 DOI: 10.1016/j.celrep.2018.04.093] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 03/05/2018] [Accepted: 04/23/2018] [Indexed: 01/28/2023] Open
Abstract
The β-barrel assembly machinery (BAM) complex is essential for localization of surface proteins on bacterial cells, but the mechanism by which it functions is unclear. We developed a direct stochastic optical reconstruction microscopy (dSTORM) methodology to view the BAM complex in situ. Single-cell analysis showed that discrete membrane precincts housing several BAM complexes are distributed across the E. coli surface, with a nearest neighbor distance of ∼200 nm. The auxiliary lipoprotein subunit BamB was crucial for this spatial distribution, and in situ crosslinking shows that BamB makes intimate contacts with BamA and BamB in neighboring BAM complexes within the precinct. The BAM complex precincts swell when outer membrane protein synthesis is maximal, visual proof that the precincts are active in protein assembly. This nanoscale interrogation of the BAM complex in situ suggests a model whereby bacterial outer membranes contain highly organized assembly precincts to drive integral protein assembly.
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Affiliation(s)
- Sachith D Gunasinghe
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Takuya Shiota
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia; Organization for Promotion of Tenure Track, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Christopher J Stubenrauch
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Keith E Schulze
- Monash Micro Imaging, Monash University, Clayton, VIC 3800, Australia
| | - Chaille T Webb
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Alex J Fulcher
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia; Monash Micro Imaging, Monash University, Clayton, VIC 3800, Australia; Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Biochemistry & Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - Rhys A Dunstan
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Iain D Hay
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Thomas Naderer
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Biochemistry & Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - Donna R Whelan
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Toby D M Bell
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
| | - Kirstin D Elgass
- Monash Micro Imaging, Monash University, Clayton, VIC 3800, Australia; Hudson Institute of Medical Research, Clayton, VIC 3800, Australia
| | - Richard A Strugnell
- Department of Microbiology & Immunology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Trevor Lithgow
- Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
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37
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Zhu T, McClure R, Harrison OB, Genco C, Massari P. Integrated Bioinformatic Analyses and Immune Characterization of New Neisseria gonorrhoeae Vaccine Antigens Expressed during Natural Mucosal Infection. Vaccines (Basel) 2019; 7:E153. [PMID: 31627489 PMCID: PMC6963464 DOI: 10.3390/vaccines7040153] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/11/2019] [Accepted: 10/14/2019] [Indexed: 02/07/2023] Open
Abstract
There is an increasingly severe trend of antibiotic-resistant Neisseria gonorrhoeae strains worldwide and new therapeutic strategies are needed against this sexually-transmitted pathogen. Despite the urgency, progress towards a gonococcal vaccine has been slowed by a scarcity of suitable antigens, lack of correlates of protection in humans and limited animal models of infection. N. gonorrhoeae gene expression levels in the natural human host does not reflect expression in vitro, further complicating in vitro-basedvaccine analysis platforms. We designed a novel candidate antigen selection strategy (CASS), based on a reverse vaccinology-like approach coupled with bioinformatics. We utilized the CASS to mine gonococcal proteins expressed during human mucosal infection, reported in our previous studies, and focused on a large pool of hypothetical proteins as an untapped source of potential new antigens. Via two discovery and analysis phases (DAP), we identified 36 targets predicted to be immunogenic, membrane-associated proteins conserved in N. gonorrhoeae and suitable for recombinant expression. Six initial candidates were produced and used to immunize mice. Characterization of the immune responses indicated cross-reactive antibodies and serum bactericidal activity against different N. gonorrhoeae strains. These results support the CASS as a tool for the discovery of new vaccine candidates.
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Affiliation(s)
- Tianmou Zhu
- Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA.
| | - Ryan McClure
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
| | - Odile B Harrison
- Department of Zoology, University of Oxford, Oxford OX1 3SY, UK.
| | - Caroline Genco
- Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA.
| | - Paola Massari
- Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA.
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38
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Wu R, Stephenson R, Gichaba A, Noinaj N. The big BAM theory: An open and closed case? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183062. [PMID: 31520605 DOI: 10.1016/j.bbamem.2019.183062] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 09/02/2019] [Accepted: 09/04/2019] [Indexed: 12/16/2022]
Abstract
The β-barrel assembly machinery (BAM) is responsible for the biogenesis of outer membrane proteins (OMPs) into the outer membranes of Gram-negative bacteria. These OMPs have a membrane-embedded domain consisting of a β-barrel fold which can vary from 8 to 36 β-strands, with each serving a diverse role in the cell such as nutrient uptake and virulence. BAM was first identified nearly two decades ago, but only recently has the molecular structure of the full complex been reported. Together with many years of functional characterization, we have a significantly clearer depiction of BAM's structure, the intra-complex interactions, conformational changes that BAM may undergo during OMP biogenesis, and the role chaperones may play. But still, despite advances over the past two decades, the mechanism for BAM-mediated OMP biogenesis remains elusive. Over the years, several theories have been proposed that have varying degrees of support from the literature, but none has of yet been conclusive enough to be widely accepted as the sole mechanism. We will present a brief history of BAM, the recent work on the structures of BAM, and a critical analysis of the current theories for how it may function.
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Affiliation(s)
- Runrun Wu
- Markey Center for Structural Biology, Department of Biological Sciences, and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, 47907, USA
| | - Robert Stephenson
- Markey Center for Structural Biology, Department of Biological Sciences, and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, 47907, USA
| | - Abigail Gichaba
- Markey Center for Structural Biology, Department of Biological Sciences, and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, 47907, USA
| | - Nicholas Noinaj
- Markey Center for Structural Biology, Department of Biological Sciences, and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, 47907, USA.
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39
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Hews CL, Cho T, Rowley G, Raivio TL. Maintaining Integrity Under Stress: Envelope Stress Response Regulation of Pathogenesis in Gram-Negative Bacteria. Front Cell Infect Microbiol 2019; 9:313. [PMID: 31552196 PMCID: PMC6737893 DOI: 10.3389/fcimb.2019.00313] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/19/2019] [Indexed: 12/20/2022] Open
Abstract
The Gram-negative bacterial envelope is an essential interface between the intracellular and harsh extracellular environment. Envelope stress responses (ESRs) are crucial to the maintenance of this barrier and function to detect and respond to perturbations in the envelope, caused by environmental stresses. Pathogenic bacteria are exposed to an array of challenging and stressful conditions during their lifecycle and, in particular, during infection of a host. As such, maintenance of envelope homeostasis is essential to their ability to successfully cause infection. This review will discuss our current understanding of the σE- and Cpx-regulated ESRs, with a specific focus on their role in the virulence of a number of model pathogens.
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Affiliation(s)
- Claire L Hews
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Timothy Cho
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Tracy L Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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40
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Awanye AM, Chang CM, Wheeler JX, Chan H, Marsay L, Dold C, Rollier CS, Bird LE, Nettleship JE, Owens RJ, Pollard AJ, Derrick JP. Immunogenicity profiling of protein antigens from capsular group B Neisseria meningitidis. Sci Rep 2019; 9:6843. [PMID: 31048732 PMCID: PMC6497663 DOI: 10.1038/s41598-019-43139-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 04/11/2019] [Indexed: 11/29/2022] Open
Abstract
Outer membrane vesicle (OMV)- based vaccines have been used to provide strain-specific protection against capsular group B Neisseria meningitidis infections, but the full breadth of the immune response against the components of the OMV has not been established. Sera from adults vaccinated with an OMV vaccine were used to screen 91 outer membrane proteins (OMPs) incorporated in an antigen microarray panel. Antigen-specific IgG levels were quantified pre-vaccination, and after 12 and 18 weeks. These results were compared with IgG levels from mice vaccinated with the same OMV vaccine. The repertoires of highly responding antigens in humans and mice overlapped, but were not identical. The highest responding antigens to human IgG comprised four integral OMPs (PorA, PorB, OpcA and PilQ), a protein which promotes the stability of PorA and PorB (RmpM) and two lipoproteins (BamC and GNA1162). These observations will assist in evaluating the role of minor antigen components within OMVs in providing protection against meningococcal infection. In addition, the relative dominance of responses to integral OMPs in humans emphasizes the importance of this subclass and points to the value of maintaining conformational epitopes from integral membrane proteins in vaccine formulations.
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Affiliation(s)
- Amaka M Awanye
- Lydia Becker Institute of Immunology and Inflammation, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PL, UK
| | - Chun-Mien Chang
- Lydia Becker Institute of Immunology and Inflammation, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PL, UK
| | - Jun X Wheeler
- National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Hertfordshire, EN6 3QG, UK
| | - Hannah Chan
- National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Hertfordshire, EN6 3QG, UK
| | - Leanne Marsay
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, OX3 7LE, UK
| | - Christina Dold
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, OX3 7LE, UK
| | - Christine S Rollier
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, OX3 7LE, UK
| | - Louise E Bird
- Oxford Protein Production Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Didcot, OX11 0FA, UK
| | - Joanne E Nettleship
- Oxford Protein Production Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Didcot, OX11 0FA, UK
| | - Raymond J Owens
- Oxford Protein Production Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Didcot, OX11 0FA, UK
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, OX3 7LE, UK
| | - Jeremy P Derrick
- Lydia Becker Institute of Immunology and Inflammation, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PL, UK.
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41
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Abstract
The biogenesis of periplasmic and outer membrane proteins (OMPs) in Escherichia coli is assisted by a variety of processes that help with their folding and transport to their final destination in the cellular envelope. Chaperones are macromolecules, usually proteins, that facilitate the folding of proteins or prevent their aggregation without becoming part of the protein's final structure. Because chaperones often bind to folding intermediates, they often (but not always) act to slow protein folding. Protein folding catalysts, on the other hand, act to accelerate specific steps in the protein folding pathway, including disulfide bond formation and peptidyl prolyl isomerization. This review is primarily concerned with E. coli and Salmonella periplasmic and cellular envelope chaperones; it also discusses periplasmic proline isomerization.
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42
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Ricci DP, Silhavy TJ. Outer Membrane Protein Insertion by the β-barrel Assembly Machine. EcoSal Plus 2019; 8:10.1128/ecosalplus.ESP-0035-2018. [PMID: 30869065 PMCID: PMC6419762 DOI: 10.1128/ecosalplus.esp-0035-2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Like all outer membrane (OM) constituents, integral OM β-barrel proteins in Gram-negative bacteria are synthesized in the cytoplasm and trafficked to the OM, where they are locally assembled into the growing OM by the ubiquitous β-barrel assembly machine (Bam). While the identities and structures of all essential and accessory Bam components have been determined, the basic mechanism of Bam-assisted OM protein integration remains elusive. Here we review mechanistic analyses of OM β-barrel protein folding and Bam dynamics and summarize recent insights that inform a general model for OM protein recognition and assembly by the Bam complex.
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Affiliation(s)
- Dante P Ricci
- Department of Early Research, Achaogen, Inc., South San Francisco, CA 94080
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
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43
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Chauhan N, Hatlem D, Orwick-Rydmark M, Schneider K, Floetenmeyer M, van Rossum B, Leo JC, Linke D. Insights into the autotransport process of a trimeric autotransporter, Yersinia Adhesin A (YadA). Mol Microbiol 2019; 111:844-862. [DOI: 10.1111/mmi.14195] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Nandini Chauhan
- Department of Biosciences; University of Oslo; Blindernveien 31 0371 Oslo Norway
- Max Planck Institute for Developmental Biology, Department 1; 72076 Tübingen Germany
| | - Daniel Hatlem
- Department of Biosciences; University of Oslo; Blindernveien 31 0371 Oslo Norway
| | | | - Kenneth Schneider
- Department of Biosciences; University of Oslo; Blindernveien 31 0371 Oslo Norway
| | - Matthias Floetenmeyer
- Max Planck Institute for Developmental Biology, Department 1; 72076 Tübingen Germany
- The Centre for Microscopy and Microanalysis, The University of Queensland; 4072 St. Lucia Queensland Australia
| | - Barth van Rossum
- Forschungsinstitut für Molekulare Pharmakologie; Department of NMR-Supported Structural Biology; Berlin Germany
| | - Jack C. Leo
- Department of Biosciences; University of Oslo; Blindernveien 31 0371 Oslo Norway
- Max Planck Institute for Developmental Biology, Department 1; 72076 Tübingen Germany
| | - Dirk Linke
- Department of Biosciences; University of Oslo; Blindernveien 31 0371 Oslo Norway
- Max Planck Institute for Developmental Biology, Department 1; 72076 Tübingen Germany
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44
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Humes JR, Schiffrin B, Calabrese AN, Higgins AJ, Westhead DR, Brockwell DJ, Radford SE. The Role of SurA PPIase Domains in Preventing Aggregation of the Outer-Membrane Proteins tOmpA and OmpT. J Mol Biol 2019; 431:1267-1283. [PMID: 30716334 DOI: 10.1016/j.jmb.2019.01.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 01/22/2019] [Accepted: 01/25/2019] [Indexed: 10/27/2022]
Abstract
SurA is a conserved ATP-independent periplasmic chaperone involved in the biogenesis of outer-membrane proteins (OMPs). Escherichia coli SurA has a core domain and two peptidylprolyl isomerase (PPIase) domains, the role(s) of which remain unresolved. Here we show that while SurA homologues in early proteobacteria typically contain one or no PPIase domains, the presence of two PPIase domains is common in SurA in later proteobacteria, implying an evolutionary advantage for this domain architecture. Bioinformatics analysis of >350,000 OMP sequences showed that their length, hydrophobicity and aggregation propensity are similar across the proteobacterial classes, ruling out a simple correlation between SurA domain architecture and these properties of OMP sequences. To investigate the role of the PPIase domains in SurA activity, we deleted one or both PPIase domains from E.coli SurA and investigated the ability of the resulting proteins to bind and prevent the aggregation of tOmpA (19 kDa) and OmpT (33 kDa). The results show that wild-type SurA inhibits the aggregation of both OMPs, as do the cytoplasmic OMP chaperones trigger factor and SecB. However, while the ability of SurA to bind and prevent tOmpA aggregation does not depend on its PPIase domains, deletion of even a single PPIase domain ablates the ability of SurA to prevent OmpT aggregation. The results demonstrate that the core domain of SurA endows its generic chaperone ability, while the presence of PPIase domains enhances its chaperone activity for specific OMPs, suggesting one reason for the conservation of multiple PPIase domains in SurA in proteobacteria.
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Affiliation(s)
- Julia R Humes
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Bob Schiffrin
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anna J Higgins
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - David R Westhead
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - David J Brockwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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45
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Immunotopological Analysis of the Treponema denticola Major Surface Protein (Msp). J Bacteriol 2018; 201:JB.00528-18. [PMID: 30373754 DOI: 10.1128/jb.00528-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/22/2018] [Indexed: 12/17/2022] Open
Abstract
Treponema denticola, one of several recognized periodontal pathogens, is a model organism for studying Treponema physiology and host-microbe interactions. Its major surface protein Msp (or MOSP) comprises an oligomeric outer membrane-associated complex that binds fibronectin, has cytotoxic pore-forming activity, and disrupts several intracellular responses. There are two hypotheses regarding native Msp structure and membrane topology. One hypothesis predicts that the entire Msp protein forms a β-barrel structure similar to that of well-studied outer membrane porins of Gram-negative bacteria. The second hypothesis predicts a bipartite Msp with distinct and separate periplasmic N-terminal and porin-like β-barrel C-terminal domains. The bipartite model, based on bioinformatic analysis of the orthologous Treponema pallidum Tpr proteins, is supported largely by studies of recombinant TprC and Msp polypeptides. The present study reports immunological studies in both T. denticola and Escherichia coli backgrounds to identify a prominent Msp surface epitope (residues 229 to 251 in ATCC 35405) in a domain that differs between strains with otherwise highly conserved Msps. These results were then used to evaluate a series of in silico structural models of representative T. denticola Msps. The data presented here are consistent with a model of Msp as a large-diameter β-barrel porin. This work adds to the knowledge regarding the diverse Msp-like proteins in oral treponemes and may contribute to an understanding of the evolutionary and potential functional relationships between Msps of oral Treponema and the orthologous group of Tpr proteins of T. pallidum. IMPORTANCE Treponema denticola is among a small subset of the oral microbiota contributing to severe periodontal disease. Due to its relative genetic tractability, T. denticola is a model organism for studying Treponema physiology and host-microbe interactions. T. denticola Msp is a highly expressed outer membrane-associated oligomeric protein that binds fibronectin, has cytotoxic pore-forming activity, and disrupts intracellular regulatory pathways. It shares homology with the orthologous group of T. pallidum Tpr proteins, one of which is implicated in T. pallidum in vivo antigenic variation. The outer membrane topologies of both Msp and the Tpr family proteins are unresolved, with conflicting reports on protein domain localization and function. In this study, we combined empirical immunological data derived both from diverse T. denticola strains and from recombinant Msp expression in E. coli with in silico predictive structural modeling of T. denticola Msp membrane topology, to move toward resolution of this important issue in Treponema biology.
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46
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Gwin CM, Prakash N, Christian Belisario J, Haider L, Rosen ML, Martinez LR, Rigel NW. The apolipoprotein N-acyl transferase Lnt is dispensable for growth in Acinetobacter species. MICROBIOLOGY-SGM 2018; 164:1547-1556. [PMID: 30307391 DOI: 10.1099/mic.0.000726] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Directing the flow of protein traffic is a critical task faced by all cellular organisms. In Gram-negative bacteria, this traffic includes lipoproteins. Lipoproteins are synthesized as precursors in the cytoplasm and receive their acyl modifications upon export across the inner membrane. The third and final acyl chain is added by Lnt, which until recently was thought to be essential in all Gram-negatives. In this report, we show that Acinetobacter species can also tolerate a complete loss-of-function mutation in lnt. Absence of a fully functional Lnt impairs modification of lipoproteins, increases outer membrane permeability and susceptibility to antibiotics, and alters normal cellular morphology. In addition, we show that loss of lnt triggers a global transcriptional response to this added cellular stress. Taken together, our findings provide new insights on and support the growing revisions to the Gram-negative lipoprotein biogenesis paradigm.
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Affiliation(s)
- Celena M Gwin
- 1Department of Biology, Hofstra University, Hempstead, NY, USA.,2Department of Microbial Pathogenesis, Yale University, New Haven, CT, USA
| | - Natalia Prakash
- 1Department of Biology, Hofstra University, Hempstead, NY, USA
| | - J Christian Belisario
- 3Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA
| | - Lubaina Haider
- 1Department of Biology, Hofstra University, Hempstead, NY, USA.,4College of Medicine, SUNY-Downstate Medical Center, Brooklyn, NY, USA
| | - Marlene L Rosen
- 1Department of Biology, Hofstra University, Hempstead, NY, USA
| | - Luis R Martinez
- 3Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA.,5Department of Biological Sciences, The Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX, USA
| | - Nathan W Rigel
- 1Department of Biology, Hofstra University, Hempstead, NY, USA
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47
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Torres VVL, Heinz E, Stubenrauch CJ, Wilksch JJ, Cao H, Yang J, Clements A, Dunstan RA, Alcock F, Webb CT, Dougan G, Strugnell RA, Hay ID, Lithgow T. An investigation into the Omp85 protein BamK in hypervirulent Klebsiella pneumoniae, and its role in outer membrane biogenesis. Mol Microbiol 2018; 109:584-599. [PMID: 29873128 DOI: 10.1111/mmi.13990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2018] [Indexed: 12/29/2022]
Abstract
Members of the Omp85 protein superfamily have important roles in Gram-negative bacteria, with the archetypal protein BamA being ubiquitous given its essential function in the assembly of outer membrane proteins. In some bacterial lineages, additional members of the family exist and, in most of these cases, the function of the protein is unknown. We detected one of these Omp85 proteins in the pathogen Klebsiella pneumoniae B5055, and refer to the protein as BamK. Here, we show that bamK is a conserved element in the core genome of Klebsiella, and its expression rescues a loss-of-function ∆bamA mutant. We developed an E. coli model system to measure and compare the specific activity of BamA and BamK in the assembly reaction for the critical substrate LptD, and find that BamK is as efficient as BamA in assembling the native LptDE complex. Comparative structural analysis revealed that the major distinction between BamK and BamA is in the external facing surface of the protein, and we discuss how such changes may contribute to a mechanism for resistance against infection by bacteriophage.
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Affiliation(s)
- Von Vergel L Torres
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia
| | - Eva Heinz
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia.,Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Christopher J Stubenrauch
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia
| | - Jonathan J Wilksch
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia.,Department of Microbiology & Immunology, University of Melbourne, Parkville, 3052, Australia
| | - Hanwei Cao
- Department of Microbiology & Immunology, University of Melbourne, Parkville, 3052, Australia
| | - Ji Yang
- Department of Microbiology & Immunology, University of Melbourne, Parkville, 3052, Australia
| | - Abigail Clements
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia.,MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Rhys A Dunstan
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia.,Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Felicity Alcock
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia.,Department of Biochemistry, Oxford University, Oxford, UK
| | - Chaille T Webb
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Richard A Strugnell
- Department of Microbiology & Immunology, University of Melbourne, Parkville, 3052, Australia
| | - Iain D Hay
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia
| | - Trevor Lithgow
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, 3800, Australia
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48
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POTRA Domains, Extracellular Lid, and Membrane Composition Modulate the Conformational Stability of the β Barrel Assembly Factor BamA. Structure 2018; 26:987-996.e3. [PMID: 29861346 DOI: 10.1016/j.str.2018.04.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 03/30/2018] [Accepted: 04/27/2018] [Indexed: 11/21/2022]
Abstract
The core component BamA of the β barrel assembly machinery (BAM) adopts several conformations, which are thought to facilitate the insertion and folding of β barrel proteins into the bacterial outer membrane. Which factors alter the stability of these conformations remains to be quantified. Here, we apply single-molecule force spectroscopy to characterize the mechanical properties of BamA from Escherichia coli. In contrast to the N-terminal periplasmic polypeptide-transport-associated (POTRA) domains, the C-terminal transmembrane β barrel domain of BamA is mechanically much more stable. Exposed to mechanical stress this β barrel stepwise unfolds β hairpins until unfolding has been completed. Thereby, the mechanical stabilities of β barrel and β hairpins are modulated by the POTRA domains, the membrane composition and the extracellular lid closing the β barrel. We anticipate that these differences in stability, which are caused by factors contributing to BAM function, promote conformations of the BamA β barrel required to insert and fold outer membrane proteins.
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49
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Abstract
The hallmark of gram-negative bacteria and organelles such as mitochondria and chloroplasts is the presence of an outer membrane. In bacteria such as Escherichia coli, the outer membrane is a unique asymmetric lipid bilayer with lipopolysaccharide in the outer leaflet. Integral transmembrane proteins assume a β-barrel structure, and their assembly is catalyzed by the heteropentameric Bam complex containing the outer membrane protein BamA and four lipoproteins, BamB-E. How the Bam complex assembles a great diversity of outer membrane proteins into a membrane without an obvious energy source is a particularly challenging problem, because folding intermediates are predicted to be unstable in either an aqueous or a hydrophobic environment. Two models have been put forward: the budding model, based largely on structural data, and the BamA assisted model, based on genetic and biochemical studies. Here we offer a critical discussion of the pros and cons of each.
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Affiliation(s)
- Anna Konovalova
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544;
| | - Daniel E Kahne
- Department of Chemistry and Chemical Biology and.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544;
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50
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Botos I, Noinaj N, Buchanan SK. Insertion of proteins and lipopolysaccharide into the bacterial outer membrane. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630161 DOI: 10.1098/rstb.2016.0224] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The bacterial outer membrane contains phospholipids in the inner leaflet and lipopolysaccharide (LPS) in the outer leaflet. Both proteins and LPS must be frequently inserted into the outer membrane to preserve its integrity. The protein complex that inserts LPS into the outer membrane is called LptDE, and consists of an integral membrane protein, LptD, with a separate globular lipoprotein, LptE, inserted in the barrel lumen. The protein complex that inserts newly synthesized outer-membrane proteins (OMPs) into the outer membrane is called the BAM complex, and consists of an integral membrane protein, BamA, plus four lipoproteins, BamB, C, D and E. Recent structural and functional analyses illustrate how these two complexes insert their substrates into the outer membrane by distorting the membrane component (BamA or LptD) to directly access the lipid bilayer.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Istvan Botos
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nicholas Noinaj
- Markey Center for Structural Biology, Department of Biological Sciences, and the Purdue Institute for Inflammation, Immunology and Infectious Diseases, Purdue University, West Lafayette, Indiana 47907, USA
| | - Susan K Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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