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Paul Ikujuni A, Dhar R, Cordova A, Bowman AM, Noga S, Slusky JSG. Discovery and Characterization of Two Folded Intermediates for Outer Membrane Protein TolC Biogenesis. J Mol Biol 2024:168652. [PMID: 38871177 DOI: 10.1016/j.jmb.2024.168652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 05/12/2024] [Accepted: 06/06/2024] [Indexed: 06/15/2024]
Abstract
TolC is the outer membrane protein responsible for antibiotic efflux in E. coli. Compared to other outer membrane proteins it has an unusual fold and has been shown to fold independently of commonly used periplasmic chaperones, SurA and Skp. Here we find that the assembly of TolC involves the formation of two folded intermediates using circular dichroism, gel electrophoresis, site-specific disulfide bond formation and radioactive labeling. First the TolC monomer folds, and then TolC assembles into a trimer both in detergent-free buffer and in the presence of detergent micelles. We find that a TolC trimer also forms in the periplasm and is present in the periplasm before it inserts in the outer membrane. The monomeric and trimeric folding intermediates may be used in the future to develop a new approach to antibiotic efflux pump inhibition by targeting the assembly pathway of TolC.
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Affiliation(s)
- Ayotunde Paul Ikujuni
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045
| | - Rik Dhar
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045
| | - Andres Cordova
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045
| | - Alexander M Bowman
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045
| | - Sarah Noga
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045
| | - Joanna S G Slusky
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045; Computational Biology Program, The University of Kansas, 2030 Becker Dr., Lawrence, KS 66045-7534.
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2
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Pastora AB, Rzasa KM, O'Toole GA. Multiple pathways impact the swarming motility of Pseudomonas fluorescens Pf0-1. Microbiol Spectr 2024; 12:e0016624. [PMID: 38687073 DOI: 10.1128/spectrum.00166-24] [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: 01/17/2024] [Accepted: 04/20/2024] [Indexed: 05/02/2024] Open
Abstract
Swarming motility in pseudomonads typically requires both a functional flagellum and the production/secretion of a biosurfactant. Published work has shown that the wild-type Pseudomonas fluorescens Pf0-1 is swarming deficient due to a point mutation in the gacA gene, which until recently was thought to inactivate rather than attenuate the Gac/Rsm pathway. As a result, little is known about the underlying mechanisms that regulate swarming motility by P. fluorescens Pf0-1. Here, we demonstrate that a ΔrsmA ΔrsmE ΔrsmI mutant, which phenotypically mimics Gac/Rsm pathway overstimulation, is proficient at swarming motility. RsmA and RsmE appear to play a key role in this regulation. Transposon mutagenesis of the ΔrsmA ΔrsmE ΔrsmI mutant identified multiple factors that impact swarming motility, including pathways involved in flagellar synthesis and biosurfactant production/secretion. We find that loss of genes linked to biosurfactant Gacamide A biosynthesis or secretion impacts swarming motility, as does loss of the alternative sigma factor FliA, which results in a defect in flagellar function. Collectively, these findings provide evidence that P. fluorescens Pf0-1 can swarm if the Gac/Rsm pathway is activated, highlight the regulatory complexity of swarming motility in this strain, and demonstrate that the cyclic lipopeptide Gacamide A is utilized as a biosurfactant for swarming motility.IMPORTANCESwarming motility is a coordinated process that allows communities of bacteria to collectively move across a surface. For P. fluorescens Pf0-1, this phenotype is notably absent in the parental strain, and to date, little is known about the regulation of swarming in this strain. Here, we identify RsmA and RsmE as key repressors of swarming motility via modulating the levels of biosurfactant production/secretion. Using transposon mutagenesis and subsequent genetic analyses, we further identify potential regulatory mechanisms of swarming motility and link Gacamide A biosynthesis and transport machinery to swarming motility.
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Affiliation(s)
- Alexander B Pastora
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Kara M Rzasa
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
- Thayer School of Engineering at Dartmouth, Hanover, New Hampshire, USA
| | - George A O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Chen Y, Gu J, Yang B, Yang L, Pang J, Luo Q, Li Y, Li D, Deng Z, Dong C, Dong H, Zhang Z. Structure and activity of the septal peptidoglycan hydrolysis machinery crucial for bacterial cell division. PLoS Biol 2024; 22:e3002628. [PMID: 38814940 PMCID: PMC11139282 DOI: 10.1371/journal.pbio.3002628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 04/14/2024] [Indexed: 06/01/2024] Open
Abstract
The peptidoglycan (PG) layer is a critical component of the bacterial cell wall and serves as an important target for antibiotics in both gram-negative and gram-positive bacteria. The hydrolysis of septal PG (sPG) is a crucial step of bacterial cell division, facilitated by FtsEX through an amidase activation system. In this study, we present the cryo-EM structures of Escherichia coli FtsEX and FtsEX-EnvC in the ATP-bound state at resolutions of 3.05 Å and 3.11 Å, respectively. Our PG degradation assays in E. coli reveal that the ATP-bound conformation of FtsEX activates sPG hydrolysis of EnvC-AmiB, whereas EnvC-AmiB alone exhibits autoinhibition. Structural analyses indicate that ATP binding induces conformational changes in FtsEX-EnvC, leading to significant differences from the apo state. Furthermore, PG degradation assays of AmiB mutants confirm that the regulation of AmiB by FtsEX-EnvC is achieved through the interaction between EnvC-AmiB. These findings not only provide structural insight into the mechanism of sPG hydrolysis and bacterial cell division, but also have implications for the development of novel therapeutics targeting drug-resistant bacteria.
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Affiliation(s)
- Yatian Chen
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Jiayue Gu
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Biao Yang
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Lili Yang
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Jie Pang
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Qinghua Luo
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yirong Li
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Danyang Li
- The Cryo-EM Center, Core facility of Wuhan University, Wuhan University, Wuhan, China
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Changjiang Dong
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Haohao Dong
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Zhengyu Zhang
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
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Korczak L, Majewski P, Iwaniuk D, Sacha P, Matulewicz M, Wieczorek P, Majewska P, Wieczorek A, Radziwon P, Tryniszewska E. Molecular mechanisms of tigecycline-resistance among Enterobacterales. Front Cell Infect Microbiol 2024; 14:1289396. [PMID: 38655285 PMCID: PMC11035753 DOI: 10.3389/fcimb.2024.1289396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 02/27/2024] [Indexed: 04/26/2024] Open
Abstract
The global emergence of antimicrobial resistance to multiple antibiotics has recently become a significant concern. Gram-negative bacteria, known for their ability to acquire mobile genetic elements such as plasmids, represent one of the most hazardous microorganisms. This phenomenon poses a serious threat to public health. Notably, the significance of tigecycline, a member of the antibiotic group glycylcyclines and derivative of tetracyclines has increased. Tigecycline is one of the last-resort antimicrobial drugs used to treat complicated infections caused by multidrug-resistant (MDR) bacteria, extensively drug-resistant (XDR) bacteria or even pan-drug-resistant (PDR) bacteria. The primary mechanisms of tigecycline resistance include efflux pumps' overexpression, tet genes and outer membrane porins. Efflux pumps are crucial in conferring multi-drug resistance by expelling antibiotics (such as tigecycline by direct expelling) and decreasing their concentration to sub-toxic levels. This review discusses the problem of tigecycline resistance, and provides important information for understanding the existing molecular mechanisms of tigecycline resistance in Enterobacterales. The emergence and spread of pathogens resistant to last-resort therapeutic options stands as a major global healthcare concern, especially when microorganisms are already resistant to carbapenems and/or colistin.
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Affiliation(s)
- Lukasz Korczak
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Piotr Majewski
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Dominika Iwaniuk
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Pawel Sacha
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | | | - Piotr Wieczorek
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | | | - Anna Wieczorek
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Piotr Radziwon
- Regional Centre for Transfusion Medicine, Bialystok, Poland
| | - Elzbieta Tryniszewska
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
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5
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Nasrollahian S, Graham JP, Halaji M. A review of the mechanisms that confer antibiotic resistance in pathotypes of E. coli. Front Cell Infect Microbiol 2024; 14:1387497. [PMID: 38638826 PMCID: PMC11024256 DOI: 10.3389/fcimb.2024.1387497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 03/15/2024] [Indexed: 04/20/2024] Open
Abstract
The dissemination of antibiotic resistance in Escherichia coli poses a significant threat to public health worldwide. This review provides a comprehensive update on the diverse mechanisms employed by E. coli in developing resistance to antibiotics. We primarily focus on pathotypes of E. coli (e.g., uropathogenic E. coli) and investigate the genetic determinants and molecular pathways that confer resistance, shedding light on both well-characterized and recently discovered mechanisms. The most prevalent mechanism continues to be the acquisition of resistance genes through horizontal gene transfer, facilitated by mobile genetic elements such as plasmids and transposons. We discuss the role of extended-spectrum β-lactamases (ESBLs) and carbapenemases in conferring resistance to β-lactam antibiotics, which remain vital in clinical practice. The review covers the key resistant mechanisms, including: 1) Efflux pumps and porin mutations that mediate resistance to a broad spectrum of antibiotics, including fluoroquinolones and aminoglycosides; 2) adaptive strategies employed by E. coli, including biofilm formation, persister cell formation, and the activation of stress response systems, to withstand antibiotic pressure; and 3) the role of regulatory systems in coordinating resistance mechanisms, providing insights into potential targets for therapeutic interventions. Understanding the intricate network of antibiotic resistance mechanisms in E. coli is crucial for the development of effective strategies to combat this growing public health crisis. By clarifying these mechanisms, we aim to pave the way for the design of innovative therapeutic approaches and the implementation of prudent antibiotic stewardship practices to preserve the efficacy of current antibiotics and ensure a sustainable future for healthcare.
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Affiliation(s)
- Sina Nasrollahian
- Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Jay P. Graham
- Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, CA, United States
| | - Mehrdad Halaji
- Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
- Department of Medical Microbiology and Biotechnology, School of Medicine, Babol University of Medical Sciences, Babol, Iran
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Zhou L, Höfte M, Hennessy RC. Does regulation hold the key to optimizing lipopeptide production in Pseudomonas for biotechnology? Front Bioeng Biotechnol 2024; 12:1363183. [PMID: 38476965 PMCID: PMC10928948 DOI: 10.3389/fbioe.2024.1363183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 02/12/2024] [Indexed: 03/14/2024] Open
Abstract
Lipopeptides (LPs) produced by Pseudomonas spp. are specialized metabolites with diverse structures and functions, including powerful biosurfactant and antimicrobial properties. Despite their enormous potential in environmental and industrial biotechnology, low yield and high production cost limit their practical use. While genome mining and functional genomics have identified a multitude of LP biosynthetic gene clusters, the regulatory mechanisms underlying their biosynthesis remain poorly understood. We propose that regulation holds the key to unlocking LP production in Pseudomonas for biotechnology. In this review, we summarize the structure and function of Pseudomonas-derived LPs and describe the molecular basis for their biosynthesis and regulation. We examine the global and specific regulator-driven mechanisms controlling LP synthesis including the influence of environmental signals. Understanding LP regulation is key to modulating production of these valuable compounds, both quantitatively and qualitatively, for industrial and environmental biotechnology.
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Affiliation(s)
- Lu Zhou
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Monica Höfte
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Rosanna C. Hennessy
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
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7
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Ren J, Wang M, Zhou W, Liu Z. Efflux pumps as potential targets for biofilm inhibition. Front Microbiol 2024; 15:1315238. [PMID: 38596384 PMCID: PMC11002903 DOI: 10.3389/fmicb.2024.1315238] [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] [Received: 10/10/2023] [Accepted: 01/26/2024] [Indexed: 04/11/2024] Open
Abstract
Biofilms account for a great deal of infectious diseases and contribute significantly to antimicrobial resistance. Efflux pumps confer antimicrobial resistance to microorganisms and involve multiple processes of biofilm formation. Efflux pump inhibitors (EPIs) are attracting considerable attention as a biofilm inhibition strategy. The regulatory functions of efflux pumps in biofilm formation such as mediating adherence, quorum sensing (QS) systems, and the expression of biofilm-associated genes have been increasingly identified. The versatile properties confer efflux pumps both positive and negative effects on biofilm formation. Furthermore, the expression and function of efflux pumps in biofilm formation are species-specific. Therefore, this review aims to detail the double-edged sword role of efflux pumps in biofilm formation to provide potential inhibition targets and give an overview of the effects of EPIs on biofilm formation.
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Affiliation(s)
| | | | - Wenjuan Zhou
- Department of Implantology, Yantai Stomatological Hospital Affiliated to Binzhou Medical University, Yantai, China
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Harindintwali JD, Dou Q, Wen X, Xiang L, Fu Y, Xia L, Jia Z, Jiang X, Jiang J, Wang F. Physiological and transcriptomic changes drive robust responses in Paenarthrobacter sp. AT5 to co-exposure of sulfamethoxazole and atrazine. JOURNAL OF HAZARDOUS MATERIALS 2024; 462:132795. [PMID: 37865076 DOI: 10.1016/j.jhazmat.2023.132795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/07/2023] [Accepted: 10/14/2023] [Indexed: 10/23/2023]
Abstract
Agricultural waterways are often contaminated with herbicide and antibiotic residues due to the widespread use of these chemicals in modern agriculture. The search for resistant bacterial strains that can adapt to and degrade these mixed contaminants is essential for effective in situ bioremediation. Herein, by integrating chemical and transcriptomic analyses, we shed light on mechanisms through which Paenarthrobacter sp. AT5, a well-known atrazine-degrading bacterial strain, can adapt to sulfamethoxazole (SMX) while degrading atrazine. When exposed to SMX and/or atrazine, strain AT5 increased the production of extracellular polymeric substances and reactive oxygen species, as well as the rate of activity of antioxidant enzymes. Atrazine and SMX, either alone or combined, increased the expression of genes involved in antioxidant responses, multidrug resistance, DNA repair, and membrane transport of lipopolysaccharides. Unlike atrazine alone, co-exposure with SMX reduced the expression of genes encoding enzymes involved in the lower part of the atrazine degradation pathway. Overall, these findings emphasize the complexity of bacterial adaptation to mixed herbicide and antibiotic residues and highlight the potential of strain AT5 in bioremediation efforts.
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Affiliation(s)
- Jean Damascene Harindintwali
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qingyuan Dou
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Wen
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Leilei Xiang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhao Fu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Xia
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Zhongjun Jia
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China; Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Xin Jiang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiandong Jiang
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Fang Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China; Central Institute for Engineering, Electronics and Analytics, Forschungszentrum Jülich, Jülich 52428, Germany; RWTH Aachen University, Institute for Environmental Research, WorringerWeg 1, 52074 Aachen, Germany.
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9
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Huang L, Guo F, Li X, Wang M, Zhu D, Wang M, Jia R, Chen S, Zhao X, Zhang S, Gao Q, Yang Q, Wu Y, Huang J, Tian B, Ou X, Sun D, Mao S, Zhang L, Yu Y, Götz F, Cheng A, Liu M. Functional characterization of two TolC in the resistance to drugs and metals and in the virulence of Riemerella anatipestifer. Appl Environ Microbiol 2023; 89:e0130823. [PMID: 38038982 PMCID: PMC10734528 DOI: 10.1128/aem.01308-23] [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: 07/29/2023] [Accepted: 10/18/2023] [Indexed: 12/02/2023] Open
Abstract
IMPORTANCE Riemerella anatipestifer (RA) is a notorious duck pathogen, characterized by a multitude of serotypes that exhibit no cross-reaction with one another. Moreover, RA is resistant to various antibacterial agents. Consequently, understanding the mechanisms behind resistance and identifying potential targets for drug development have become pressing needs. In this study, we show that the two TolC proteins play a role in the resistance to different drugs and metals and in the virulence. The results suggest that TolCA has a wider range of efflux substrates than TolCB. Except for gentamicin, neither TolCA nor TolCB was involved in the efflux of the other tested antibiotics. Strikingly, TolCA but not TolCB enhanced the frequency of resistance-conferring mutations. Moreover, TolCA was involved in RA virulence. Given its conservation in RA, TolCA has potential as a drug target for the development of therapeutics against RA infections.
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Affiliation(s)
- Li Huang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- College of Animal Husbandry and Veterinary Medicine, Southwest Minzu University, Chengdu, China
| | - Fang Guo
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiao Li
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mengying Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Dekang Zhu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mingshu Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Renyong Jia
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shun Chen
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinxin Zhao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shaqiu Zhang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qun Gao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qiao Yang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ying Wu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Juan Huang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Bin Tian
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xumin Ou
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Di Sun
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Sai Mao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - YanLing Yu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Friedrich Götz
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Tübingen, Germany
| | - Anchun Cheng
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mafeng Liu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People’s Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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10
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Sajeev-Sheeja A, Smorodina E, Zhang S. Structural bioinformatics studies of bacterial outer membrane beta-barrel transporters and their AlphaFold2 predicted water-soluble QTY variants. PLoS One 2023; 18:e0290360. [PMID: 37607179 PMCID: PMC10443868 DOI: 10.1371/journal.pone.0290360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/04/2023] [Indexed: 08/24/2023] Open
Abstract
Beta-barrel outer membrane proteins (OMP) are integral components of Gram-negative bacteria, eukaryotic mitochondria, and chloroplasts. They play essential roles in various cellular processes including nutrient transport, membrane stability, host-pathogen interactions, antibiotic resistance and more. The advent of AlphaFold2 for accurate protein structure predictions transformed structural bioinformatic studies. We previously used a QTY code to convert hydrophobic alpha-helices to hydrophilic alpha-helices in over 50 membrane proteins with all alpha-helices. The QTY code systematically replaces hydrophobic leucine (L), isoleucine (I), valine (V), and phenylalanine (F) with hydrophilic glutamine (Q), threonine (T), and tyrosine (Y). We here present a structural bioinformatic analysis of five outer membrane beta-barrel proteins with known molecular structures, including a) BamA, b) Omp85 (also called Sam50), c) FecA, d) Tsx, and e) OmpC. We superposed the structures of five native beta-barrel outer membrane proteins and their AlphaFold2-predicted corresponding QTY variant structures. The superposed structures of OMPs and their QTY variants exhibit remarkable structural similarity, as evidenced by residue mean square distance (RMSD) values between 0.206Å to 0.414Å despite the replacement of at least 22% (Transmembrane variation) of the amino acids in the transmembrane regions. We also show that native outer membrane proteins and QTY variants have different hydrophobicity patches. Our study provides important insights into the differences between hydrophobic and hydrophilic beta-barrels and validates the QTY code for studying beta-barrel membrane proteins and perhaps other hydrophobic aggregated proteins. Our findings demonstrate that the QTY code can be used as a simple tool for designing hydrophobic proteins in various biological contexts.
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Affiliation(s)
- Akash Sajeev-Sheeja
- Department of Chemistry, Indian Institute of Science Education and Research, Srinivasapuram, Yerpedu Mandal, Tirupati Dist, Tirupati, Andhra Pradesh, India
| | - Eva Smorodina
- Department of Immunology, Laboratory for Computational and Systems Immunology, University of Oslo, Oslo University Hospital, Oslo, Norway
| | - Shuguang Zhang
- Laboratory of Molecular Architecture, Media Lab, Massachusetts Institute of Technology, Cambridge, MA, United States of America
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11
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Chen J, Fruhauf A, Fan C, Ponce J, Ueberheide B, Bhabha G, Ekiert DC. Structure of an endogenous mycobacterial MCE lipid transporter. Nature 2023; 620:445-452. [PMID: 37495693 DOI: 10.1038/s41586-023-06366-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 06/22/2023] [Indexed: 07/28/2023]
Abstract
To replicate inside macrophages and cause tuberculosis, Mycobacterium tuberculosis must scavenge a variety of nutrients from the host1,2. The mammalian cell entry (MCE) proteins are important virulence factors in M. tuberculosis1,3, where they are encoded by large gene clusters and have been implicated in the transport of fatty acids4-7 and cholesterol1,4,8 across the impermeable mycobacterial cell envelope. Very little is known about how cargos are transported across this barrier, and it remains unclear how the approximately ten proteins encoded by a mycobacterial mce gene cluster assemble to transport cargo across the cell envelope. Here we report the cryo-electron microscopy (cryo-EM) structure of the endogenous Mce1 lipid-import machine of Mycobacterium smegmatis-a non-pathogenic relative of M. tuberculosis. The structure reveals how the proteins of the Mce1 system assemble to form an elongated ABC transporter complex that is long enough to span the cell envelope. The Mce1 complex is dominated by a curved, needle-like domain that appears to be unrelated to previously described protein structures, and creates a protected hydrophobic pathway for lipid transport across the periplasm. Our structural data revealed the presence of a subunit of the Mce1 complex, which we identified using a combination of cryo-EM and AlphaFold2, and name LucB. Our data lead to a structural model for Mce1-mediated lipid import across the mycobacterial cell envelope.
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Affiliation(s)
- James Chen
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Alice Fruhauf
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Catherine Fan
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Jackeline Ponce
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University School of Medicine, New York, NY, USA
| | - Beatrix Ueberheide
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University School of Medicine, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Gira Bhabha
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA.
| | - Damian C Ekiert
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA.
- Department of Microbiology, New York University School of Medicine, New York, NY, USA.
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12
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Li S, Gao H, Zhang H, Wei G, Shu Q, Li R, Jin S, Na G, Shi Y. The fate of antibiotic resistance genes in the coastal lagoon with multiple functional zones. J Environ Sci (China) 2023; 128:93-106. [PMID: 36801045 DOI: 10.1016/j.jes.2022.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 07/13/2022] [Accepted: 07/13/2022] [Indexed: 06/18/2023]
Abstract
Coastal lagoons provide many important services to human society, but their year-round use for aquaculture introduces large amounts of sewage. The contamination of antibiotic resistance genes (ARGs) is therefore of great concern. In this study, 50 ARGs subtypes, two integrase genes (intl1, intl2), and 16S rRNA genes were detected by high-throughput quantitative PCR, and standard curves of all target genes were prepared for quantification. The occurrence and distribution of ARGs in a typical coastal lagoon (XinCun lagoon, China) were comprehensively explored. We detected 44 and 38 subtypes of ARGs in the water and sediment, respectively, and discuss the various factors influencing the fate of ARGs in the coastal lagoon. Macrolides-lincosamides-streptogramins B was the primary ARG type, and macB was the predominant subtype. Antibiotic efflux and antibiotic inactivation were the main ARG resistance mechanisms. The XinCun lagoon was divided into eight functional zones. The ARGs showed a distinct spatial distribution owing to the influence of microbial biomass and anthropogenic activity in different functional zones. Fishing rafts, abandoned fish ponds, the town sewage zone, and mangrove wetlands provided a large quantity of ARGs to the XinCun lagoon. Nutrients and heavy metals also significantly correlated with the fate of the ARGs, especially NO2--N and Cu, which cannot be ignored. It is noteworthy that lagoon-barrier systems coupled with persistent pollutant inputs result in coastal lagoons acting as a "buffer pool" for ARGs, which can then accumulate and threaten the offshore environment.
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Affiliation(s)
- Shisheng Li
- National Marine Environmental Monsitoring Center, Dalian 116023, China; College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China
| | - Hui Gao
- National Marine Environmental Monsitoring Center, Dalian 116023, China
| | - Haibo Zhang
- National Marine Environmental Monsitoring Center, Dalian 116023, China
| | - Guangke Wei
- Laboratory for coastal marine eco-environment process and carbon sink of Hainan provincet/Yazhou Bay Innovation Institute, Hainan Tropical Ocean University, Sanya 572022, China
| | - Qin Shu
- National Marine Environmental Monsitoring Center, Dalian 116023, China; College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China
| | - Ruijing Li
- National Marine Environmental Monsitoring Center, Dalian 116023, China
| | - Shuaichen Jin
- National Marine Environmental Monsitoring Center, Dalian 116023, China
| | - Guangshui Na
- Laboratory for coastal marine eco-environment process and carbon sink of Hainan provincet/Yazhou Bay Innovation Institute, Hainan Tropical Ocean University, Sanya 572022, China; National Marine Environmental Monsitoring Center, Dalian 116023, China; College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China.
| | - Yali Shi
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China.
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13
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Kumawat M, Nabi B, Daswani M, Viquar I, Pal N, Sharma P, Tiwari S, Sarma DK, Shubham S, Kumar M. Role of bacterial efflux pump proteins in antibiotic resistance across microbial species. Microb Pathog 2023:106182. [PMID: 37263448 DOI: 10.1016/j.micpath.2023.106182] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 06/03/2023]
Abstract
Efflux proteins are transporter molecules that actively pump out a variety of substrates, including antibiotics, from cells to the environment. They are found in both Gram-positive and Gram-negative bacteria and eukaryotic cells. Based on their protein sequence homology, energy source, and overall structure, efflux proteins can be divided into seven groups. Multidrug efflux pumps are transmembrane proteins produced by microbes to enhance their survival in harsh environments and contribute to antibiotic resistance. These pumps are present in all bacterial genomes studied, indicating their ancestral origins. Many bacterial genes encoding efflux pumps are involved in transport, a significant contributor to antibiotic resistance in microbes. Efflux pumps are widely implicated in the extrusion of clinically relevant antibiotics from cells to the extracellular environment and, as such, represent a significant challenge to antimicrobial therapy. This review aims to provide an overview of the structures and mechanisms of action, substrate profiles, regulation, and possible inhibition of clinically relevant efflux pumps. Additionally, recent advances in research and the pharmacological exploitation of efflux pump inhibitors as a promising intervention for combating drug resistance will be discussed.
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Affiliation(s)
- Manoj Kumawat
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Bilkees Nabi
- Department of Biochemistry & Biochemical Engineering, SHUATS, Allahabad, 211007, India
| | - Muskan Daswani
- Department of Biotechnology, SantHirdaram Girls College, Bhopal, 462030, India
| | - Iqra Viquar
- Department of Biotechnology, SantHirdaram Girls College, Bhopal, 462030, India
| | - Namrata Pal
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Poonam Sharma
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Shikha Tiwari
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Devojit Kumar Sarma
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Swasti Shubham
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India
| | - Manoj Kumar
- Department of Microbiology, ICMR- National Institute for Research in Environmental Health, Bhopal, 462030, India.
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14
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De Gaetano GV, Lentini G, Famà A, Coppolino F, Beninati C. Antimicrobial Resistance: Two-Component Regulatory Systems and Multidrug Efflux Pumps. Antibiotics (Basel) 2023; 12:965. [PMID: 37370284 DOI: 10.3390/antibiotics12060965] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/22/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
The number of multidrug-resistant bacteria is rapidly spreading worldwide. Among the various mechanisms determining resistance to antimicrobial agents, multidrug efflux pumps play a noteworthy role because they export extraneous and noxious substrates from the inside to the outside environment of the bacterial cell contributing to multidrug resistance (MDR) and, consequently, to the failure of anti-infective therapies. The expression of multidrug efflux pumps can be under the control of transcriptional regulators and two-component systems (TCS). TCS are a major mechanism by which microorganisms sense and reply to external and/or intramembrane stimuli by coordinating the expression of genes involved not only in pathogenic pathways but also in antibiotic resistance. In this review, we describe the influence of TCS on multidrug efflux pump expression and activity in some Gram-negative and Gram-positive bacteria. Taking into account the strict correlation between TCS and multidrug efflux pumps, the development of drugs targeting TCS, alone or together with already discovered efflux pump inhibitors, may represent a beneficial strategy to contribute to the fight against growing antibiotic resistance.
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Affiliation(s)
| | - Germana Lentini
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
| | - Agata Famà
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
| | - Francesco Coppolino
- Department of Biomedical, Dental and Imaging Sciences, University of Messina, 98124 Messina, Italy
| | - Concetta Beninati
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
- Scylla Biotech Srl, 98124 Messina, Italy
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15
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McDonnell RT, Patel N, Wehrspan ZJ, Elcock AH. Atomic Models of All Major Trans-Envelope Complexes Involved in Lipid Trafficking in Escherichia Coli Constructed Using a Combination of AlphaFold2, AF2Complex, and Membrane Morphing Simulations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538765. [PMID: 37162969 PMCID: PMC10168319 DOI: 10.1101/2023.04.28.538765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In Gram-negative bacteria, several trans-envelope complexes (TECs) have been identified that span the periplasmic space in order to facilitate lipid transport between the inner- and outer- membranes. While partial or near-complete structures of some of these TECs have been solved by conventional experimental techniques, most remain incomplete. Here we describe how a combination of computational approaches, constrained by experimental data, can be used to build complete atomic models for four TECs implicated in lipid transport in Escherichia coli . We use DeepMind's protein structure prediction algorithm, AlphaFold2, and a variant of it designed to predict protein complexes, AF2Complex, to predict the oligomeric states of key components of TECs and their likely interfaces with other components. After obtaining initial models of the complete TECs by superimposing predicted structures of subcomplexes, we use the membrane orientation prediction algorithm OPM to predict the likely orientations of the inner- and outer- membrane components in each TEC. Since, in all cases, the predicted membrane orientations in these initial models are tilted relative to each other, we devise a novel molecular mechanics-based strategy that we call "membrane morphing" that adjusts each TEC model until the two membranes are properly aligned with each other and separated by a distance consistent with estimates of the periplasmic width in E. coli . The study highlights the potential power of combining computational methods, operating within limits set by both experimental data and by cell physiology, for producing useable atomic structures of very large protein complexes.
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16
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Ikujuni AP, Budiardjo SJ, Dhar R, Slusky JSG. Detergent headgroups control TolC folding in vitro. Biophys J 2023; 122:1185-1197. [PMID: 36772796 PMCID: PMC10111266 DOI: 10.1016/j.bpj.2023.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 12/29/2022] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
TolC is the trimeric outer membrane component of the efflux pump system in Escherichia coli that is responsible for antibiotic efflux from bacterial cells. Overexpression of efflux pumps has been reported to decrease susceptibility to antibiotics in a variety of bacterial pathogens. Reliable production of membrane proteins allows for the biophysical and structural characterization needed to better understand efflux and for the development of therapeutics. Preparation of recombinant protein for biochemical/structural studies often involves the production of proteins as inclusion body aggregates from which active proteins are recovered. Here, we find that the in vitro folding of TolC into its functional trimeric state from inclusion bodies is dependent on the headgroup composition of detergent micelles used. Nonionic detergent favors the formation of functional trimeric TolC, whereas zwitterionic detergents induce the formation of a non-native, oligomeric TolC fold. We also find that nonionic detergents with shorter alkyl lengths facilitate TolC folding. It remains to be seen whether the charges in lipid headgroups have similar effects on membrane insertion and folding in biological systems.
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Affiliation(s)
| | - S Jimmy Budiardjo
- Center for Computational Biology, The University of Kansas, Lawrence, Kansas
| | - Rik Dhar
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas
| | - Joanna S G Slusky
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas; Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
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17
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Bilsing FL, Anlauf MT, Hachani E, Khosa S, Schmitt L. ABC Transporters in Bacterial Nanomachineries. Int J Mol Sci 2023; 24:ijms24076227. [PMID: 37047196 PMCID: PMC10094684 DOI: 10.3390/ijms24076227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/18/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
Members of the superfamily of ABC transporters are found in all domains of life. Most of these primary active transporters act as isolated entities and export or import their substrates in an ATP-dependent manner across biological membranes. However, some ABC transporters are also part of larger protein complexes, so-called nanomachineries that catalyze the vectorial transport of their substrates. Here, we will focus on four bacterial examples of such nanomachineries: the Mac system providing drug resistance, the Lpt system catalyzing vectorial LPS transport, the Mla system responsible for phospholipid transport, and the Lol system, which is required for lipoprotein transport to the outer membrane of Gram-negative bacteria. For all four systems, we tried to summarize the existing data and provide a structure-function analysis highlighting the mechanistical aspect of the coupling of ATP hydrolysis to substrate translocation.
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18
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Stein NV, Eder M, Brameyer S, Schwenkert S, Jung H. The ABC transporter family efflux pump PvdRT-OpmQ of Pseudomonas putida KT2440: purification and initial characterization. FEBS Lett 2023; 597:1403-1414. [PMID: 36807028 DOI: 10.1002/1873-3468.14601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/31/2023] [Accepted: 02/06/2023] [Indexed: 02/20/2023]
Abstract
Tripartite efflux systems of the ABC-type family transport a variety of substrates and contribute to the antimicrobial resistance of Gram-negative bacteria. PvdRT-OpmQ, a member of this family, is thought to be involved in the secretion of the newly synthesized and recycled siderophore pyoverdine in Pseudomonas species. Here, we purified and characterized the inner membrane component PvdT and the periplasmic adapter protein PvdR of the plant growth-promoting soil bacterium Pseudomonas putida KT2440. We show that PvdT possesses an ATPase activity that is stimulated by the addition of PvdR. In addition, we provide the first biochemical evidence for direct interactions between pyoverdine and PvdRT.
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Affiliation(s)
- Nicola Victoria Stein
- Microbiology, Faculty of Biology, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Michelle Eder
- Microbiology, Faculty of Biology, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Sophie Brameyer
- Microbiology, Faculty of Biology, Ludwig Maximilians University Munich, Martinsried, Germany.,Service Unit Bioanalytics, Faculty of Biology, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Serena Schwenkert
- Service Unit Mass Spectrometry of Biomolecules, Faculty of Biology, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Heinrich Jung
- Microbiology, Faculty of Biology, Ludwig Maximilians University Munich, Martinsried, Germany
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19
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Chen J, Fruhauf A, Fan C, Ponce J, Ueberheide B, Bhabha G, Ekiert D. Structure of an endogenous mycobacterial MCE lipid transporter. RESEARCH SQUARE 2023:rs.3.rs-2412186. [PMID: 36711512 PMCID: PMC9882608 DOI: 10.21203/rs.3.rs-2412186/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
To replicate inside human macrophages and cause the disease tuberculosis, Mycobacterium tuberculosis ( Mtb ) must scavenge a variety of nutrients from the host 1,2 . The Mammalian Cell Entry (MCE) proteins are important virulence factors in Mtb 1,3 , where they are encoded in large gene clusters and have been implicated in the transport of fatty acids 4â€"7 and cholesterol 1,4,8 across the impermeable mycobacterial cell envelope. Very little is known about how cargos are transported across this barrier, and how the ~10 proteins encoded in a mycobacterial mce gene cluster might assemble to transport cargo across the cell envelope remains unknown. Here we report the cryo-EM structure of the endogenous Mce1 fatty acid import machine from Mycobacterium smegmatis , a non-pathogenic relative of Mtb . The structure reveals how the proteins of the Mce1 system assemble to form an elongated ABC transporter complex, long enough to span the cell envelope. The Mce1 complex is dominated by a curved, needle-like domain that appears to be unrelated to previously described protein structures, and creates a protected hydrophobic pathway for lipid transport across the periplasm. Unexpectedly, our structural data revealed the presence of a previously unknown subunit of the Mce1 complex, which we identified using a combination of cryo-EM and AlphaFold2, and name LucB. Our data lead to a structural model for Mce1-mediated fatty acid import across the mycobacterial cell envelope.
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20
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Hodges FJ, Torres VVL, Cunningham AF, Henderson IR, Icke C. Redefining the bacterial Type I protein secretion system. Adv Microb Physiol 2023; 82:155-204. [PMID: 36948654 DOI: 10.1016/bs.ampbs.2022.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type I secretion systems (T1SS) are versatile molecular machines for protein transport across the Gram-negative cell envelope. The archetypal Type I system mediates secretion of the Escherichia coli hemolysin, HlyA. This system has remained the pre-eminent model of T1SS research since its discovery. The classic description of a T1SS is composed of three proteins: an inner membrane ABC transporter, a periplasmic adaptor protein and an outer membrane factor. According to this model, these components assemble to form a continuous channel across the cell envelope, an unfolded substrate molecule is then transported in a one-step mechanism, directly from the cytosol to the extracellular milieu. However, this model does not encapsulate the diversity of T1SS that have been characterized to date. In this review, we provide an updated definition of a T1SS, and propose the subdivision of this system into five subgroups. These subgroups are categorized as T1SSa for RTX proteins, T1SSb for non-RTX Ca2+-binding proteins, T1SSc for non-RTX proteins, T1SSd for class II microcins, and T1SSe for lipoprotein secretion. Although often overlooked in the literature, these alternative mechanisms of Type I protein secretion offer many avenues for biotechnological discovery and application.
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Affiliation(s)
- Freya J Hodges
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Von Vergel L Torres
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Adam F Cunningham
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Ian R Henderson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| | - Christopher Icke
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
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21
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Chetri S. The culmination of multidrug-resistant efflux pumps vs. meager antibiotic arsenal era: Urgent need for an improved new generation of EPIs. Front Microbiol 2023; 14:1149418. [PMID: 37138605 PMCID: PMC10149990 DOI: 10.3389/fmicb.2023.1149418] [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] [Received: 01/21/2023] [Accepted: 03/13/2023] [Indexed: 05/05/2023] Open
Abstract
Efflux pumps function as an advanced defense system against antimicrobials by reducing the concentration of drugs inside the bacteria and extruding the substances outside. Various extraneous substances, including antimicrobials, toxic heavy metals, dyes, and detergents, have been removed by this protective barrier composed of diverse transporter proteins found in between the cell membrane and the periplasm within the bacterial cell. In this review, multiple efflux pump families have been analytically and widely outlined, and their potential applications have been discussed in detail. Additionally, this review also discusses a variety of biological functions of efflux pumps, including their role in the formation of biofilms, quorum sensing, their survivability, and the virulence in bacteria, and the genes/proteins associated with efflux pumps have also been explored for their potential relevance to antimicrobial resistance and antibiotic residue detection. A final discussion centers around efflux pump inhibitors, particularly those derived from plants.
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22
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Okada U, Murakami S. Structural and functional characteristics of the tripartite ABC transporter. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36409601 DOI: 10.1099/mic.0.001257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ATP-binding cassette (ABC) transporters are one of the largest protein superfamilies and are found in all living organisms. These transporters use the energy from ATP binding and hydrolysis to transport various substrates. In this review, we focus on the structural and functional aspects of ABC transporters, with special emphasis on type VII ABC transporters, a newly defined class possessing characteristic structures. A notable feature of type VII ABC transporters is that they assemble into tripartite complexes that span both the inner and outer membranes of Gram-negative bacteria. One of the original type VII ABC transporters, which possesses all characteristic features of this class, is the macrolide efflux transporter MacB. Recent structural analyses of MacB and homologue proteins revealed the unique mechanisms of substrate translocation by type VII ABC transporters.
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Affiliation(s)
- Ui Okada
- Department of Life Science, Tokyo Institute of Technology, Nagatsuta, Mirori-ku, Yokohama 226-8501, Japan
| | - Satoshi Murakami
- Department of Life Science, Tokyo Institute of Technology, Nagatsuta, Mirori-ku, Yokohama 226-8501, Japan
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23
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Ba Q, Zhou J, Li J, Cheng S, Zhang X, Wang H. Mutagenic Characteristics of Six Heavy Metals in Escherichia coli: The Commonality and Specificity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:13867-13877. [PMID: 36121417 PMCID: PMC9536316 DOI: 10.1021/acs.est.2c04785] [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: 07/05/2022] [Revised: 08/27/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
The history of long-term environmental exposure to heavy metals can be recorded in the genome as sporadic and specific mutations. Variable environments introduce diverse and adaptive mutations to organisms. To reveal the information hidden in genomes about environmental exposure to heavy metals, we performed long-term mutation accumulation (MA) experiments with Escherichia coli, analyzed genomes from 36 populations across 1650 generations with 6 heavy metal exposure regimes (arsenic, cadmium, chromium, copper, nickel, and lead), and inferred metal-specific evolution modes at the genomic level. All heavy metals induced genetic mutations with a mean rate of 3.459 × 10-9 per nucleotide per generation. The mutational spectrum exhibited distinct signatures; however, heavy metals also shared common mutation signatures prominently associated with all cancer types. The mutated genes showed an average similarity of 54.4% within the same exposure regime, whereas only 38.8% between exposure regimes. In terms of biological insights, mutated genes were enriched to fundamental cellular processes such as metabolism, motility, and transport. Our study elucidates the mutagenic commonality and specificity of environmental heavy metals, which are highly specific at mutational features and locus, but conserved at gene and functional levels, and may play crucial roles in the convergence of adaptation to heavy metals.
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Affiliation(s)
- Qian Ba
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingqi Zhou
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingquan Li
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Shujun Cheng
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiaokang Zhang
- School
of Public Health and Health Management, Gannan Medical University, Ganzhou 341000, China
| | - Hui Wang
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
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24
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Ekiert DC, Coudray N, Bhabha G. Structure and mechanism of the bacterial lipid ABC transporter, MlaFEDB. Curr Opin Struct Biol 2022; 76:102429. [PMID: 35981415 PMCID: PMC9509461 DOI: 10.1016/j.sbi.2022.102429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/30/2022] [Accepted: 06/16/2022] [Indexed: 11/29/2022]
Abstract
The cell envelope of Gram-negative bacteria is composed of an inner membrane, outer membane, and an intervening periplasmic space. How the outer membrane lipids are trafficked and assembled there, and how the asymmetry of the outer membrane is maintained is an area of intense research. The Mla system has been implicated in the maintenance of lipid asymmetry in the outer membrane, and is generally thought to drive the removal of mislocalized phospholipids from the outer membrane and their retrograde transport to the inner membrane. At the heart of the Mla pathway is a structurally unique ABC transporter complex in the inner membrane, called MlaFEDB. Recently, an explosion of cryo-EM studies has begun to shed light on the structure and lipid translocation mechanism of MlaFEDB, with many parallels to other ABC transporter families, including human ABCA and ABCG, as well as bacterial lipopolysaccharide and O-antigen transporters. Here we synthesize information from all available structures, and propose a model for lipid trafficking across the cell envelope by MlaFEDB.
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Affiliation(s)
- Damian C Ekiert
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA; Department of Microbiology, New York University School of Medicine, New York, NY, USA.
| | - Nicolas Coudray
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Gira Bhabha
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
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25
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Seukep AJ, Mbuntcha HG, Kuete V, Chu Y, Fan E, Guo MQ. What Approaches to Thwart Bacterial Efflux Pumps-Mediated Resistance? Antibiotics (Basel) 2022; 11:antibiotics11101287. [PMID: 36289945 PMCID: PMC9598416 DOI: 10.3390/antibiotics11101287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/16/2022] [Accepted: 09/18/2022] [Indexed: 12/03/2022] Open
Abstract
An effective response that combines prevention and treatment is still the most anticipated solution to the increasing incidence of antimicrobial resistance (AMR). As the phenomenon continues to evolve, AMR is driving an escalation of hard-to-treat infections and mortality rates. Over the years, bacteria have devised a variety of survival tactics to outwit the antibiotic’s effects, yet given their great adaptability, unexpected mechanisms are still to be discovered. Over-expression of efflux pumps (EPs) constitutes the leading strategy of bacterial resistance, and it is also a primary driver in the establishment of multidrug resistance (MDR). Extensive efforts are being made to develop antibiotic resistance breakers (ARBs) with the ultimate goal of re-sensitizing bacteria to medications to which they have become unresponsive. EP inhibitors (EPIs) appear to be the principal group of ARBs used to impair the efflux system machinery. Due to the high toxicity of synthetic EPIs, there is a growing interest in natural, safe, and innocuous ones, whereby plant extracts emerge to be excellent candidates. Besides EPIs, further alternatives are being explored including the development of nanoparticle carriers, biologics, and phage therapy, among others. What roles do EPs play in the occurrence of MDR? What weapons do we have to thwart EP-mediated resistance? What are the obstacles to their development? These are some of the core questions addressed in the present review.
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Affiliation(s)
- Armel Jackson Seukep
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 437004, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Buea, Buea P.O. Box 63, Cameroon
- Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 437004, China
- Innovation Academy for Drug Discovery and Development, Chinese Academy of Sciences, Shanghai 201203, China
| | - Helene Gueaba Mbuntcha
- Department of Biochemistry, Faculty of Science, University of Dschang, Dschang P.O. Box 67, Cameroon
| | - Victor Kuete
- Department of Biochemistry, Faculty of Science, University of Dschang, Dschang P.O. Box 67, Cameroon
| | - Yindi Chu
- State Key Laboratory of Medical Molecular Biology, Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/School of Basic Medicine, Peking Union Medical College, Beijing 100005, China
| | - Enguo Fan
- State Key Laboratory of Medical Molecular Biology, Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/School of Basic Medicine, Peking Union Medical College, Beijing 100005, China
- College of Life Sciences, Linyi University, Linyi 276005, China
- Correspondence: (E.F.); (M.-Q.G.)
| | - Ming-Quan Guo
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 437004, China
- Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 437004, China
- Innovation Academy for Drug Discovery and Development, Chinese Academy of Sciences, Shanghai 201203, China
- Correspondence: (E.F.); (M.-Q.G.)
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26
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The hemolysin A secretion system is a multi-engine pump containing three ABC transporters. Cell 2022; 185:3329-3340.e13. [DOI: 10.1016/j.cell.2022.07.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/20/2022] [Accepted: 07/18/2022] [Indexed: 11/17/2022]
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27
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Müller C, Zhang L, Zipfel S, Topitsch A, Lutz M, Eckert J, Prasser B, Chami M, Lü W, Du J, Einsle O. Molecular interplay of an assembly machinery for nitrous oxide reductase. Nature 2022; 608:626-631. [PMID: 35896743 DOI: 10.1038/s41586-022-05015-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/23/2022] [Indexed: 11/09/2022]
Abstract
Emissions of the critical ozone-depleting and greenhouse gas nitrous oxide (N2O) from soils and industrial processes have increased considerably over the last decades1-3. As the final step of bacterial denitrification, N2O is reduced to chemically inert N2 (refs. 1,4) in a reaction that is catalysed by the copper-dependent nitrous oxide reductase (N2OR) (ref. 5). The assembly of its unique [4Cu:2S] active site cluster CuZ requires both the ATP-binding-cassette (ABC) complex NosDFY and the membrane-anchored copper chaperone NosL (refs. 4,6). Here we report cryo-electron microscopy structures of Pseudomonas stutzeri NosDFY and its complexes with NosL and N2OR, respectively. We find that the periplasmic NosD protein contains a binding site for a Cu+ ion and interacts specifically with NosL in its nucleotide-free state, whereas its binding to N2OR requires a conformational change that is triggered by ATP binding. Mutually exclusive structures of NosDFY in complex with NosL and with N2OR reveal a sequential metal-trafficking and assembly pathway for a highly complex copper site. Within this pathway, NosDFY acts as a mechanical energy transducer rather than as a transporter. It links ATP hydrolysis in the cytoplasm to a conformational transition of the NosD subunit in the periplasm, which is required for NosDFY to switch its interaction partner so that copper ions are handed over from the chaperone NosL to the enzyme N2OR.
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Affiliation(s)
- Christoph Müller
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Lin Zhang
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Sara Zipfel
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Annika Topitsch
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Marleen Lutz
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Johannes Eckert
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Benedikt Prasser
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Mohamed Chami
- BioEM Lab, Biozentrum, Universität Basel, Basel, Switzerland
| | - Wei Lü
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Juan Du
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA.
| | - Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.
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28
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Ye C, Feng M, Chen Y, Zhang Y, Chen Q, Yu X. Dormancy induced by oxidative damage during disinfection facilitates conjugation of ARGs through enhancing efflux and oxidative stress: A lagging response. WATER RESEARCH 2022; 221:118798. [PMID: 35779456 DOI: 10.1016/j.watres.2022.118798] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/21/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
Disinfection is known to greatly alter bacterial characteristics in water, and high horizontal gene transfer (HGT) frequency occurs in eutrophic conditions. Interestingly, these two seemingly irrelevant phenomena were closely linked by a lagging response of the increased conjugation frequency probably via daily water disinfection in this study. Three disinfection methods (UV, chlorine, and UV/chlorine) were selected to investigate the increased frequency of conjugation of ARGs during the stage of continuing culture after disinfection. The results showed that the conjugative transfer frequency was inhibited for all disinfection treatments after 24 h of co-incubation. Unexpectedly, after 3-7 days of co-cultivation, the HGT frequencies were increased by 2.71-5.61-fold and 5.46-13.96-fold in chlorine (30 min) and UV/chlorine (1 min) groups compared to the control, but not in UV-irradiated groups. A neglected lagging response was found for the first time, i.e., oxidative disinfection-induced dormancy promotes conjugative transfer of ARGs. Furthermore, mechanistic insights were gained from (1) membrane permeability, (2) conjugation-regulated system, (3) efflux pump system, and (4) oxidative stress system, suggesting the critical role of enhancing efflux and oxidative stress in the propagation of ARGs. Finally, the known instantaneous effect of oxidation disinfection was compared to address the controversial debate in this research field, proposing that the dormancy level of donor bacteria is the key to evaluating whether it can promote the HGT process. This study has important environmental implications for elucidating the transmission of ARGs after oxidation disinfection.
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Affiliation(s)
- Chengsong Ye
- College of the Environment and Ecology, Xiamen University, Xiamen 361102, PR China
| | - Mingbao Feng
- College of the Environment and Ecology, Xiamen University, Xiamen 361102, PR China.
| | - Yuqi Chen
- College of the Environment and Ecology, Xiamen University, Xiamen 361102, PR China
| | - Yiting Zhang
- College of the Environment and Ecology, Xiamen University, Xiamen 361102, PR China
| | - Qian Chen
- College of the Environment and Ecology, Xiamen University, Xiamen 361102, PR China
| | - Xin Yu
- College of the Environment and Ecology, Xiamen University, Xiamen 361102, PR China.
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29
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Piper SJ, Johnson RM, Wootten D, Sexton PM. Membranes under the Magnetic Lens: A Dive into the Diverse World of Membrane Protein Structures Using Cryo-EM. Chem Rev 2022; 122:13989-14017. [PMID: 35849490 DOI: 10.1021/acs.chemrev.1c00837] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane proteins are highly diverse in both structure and function and can, therefore, present different challenges for structure determination. They are biologically important for cells and organisms as gatekeepers for information and molecule transfer across membranes, but each class of membrane proteins can present unique obstacles to structure determination. Historically, many membrane protein structures have been investigated using highly engineered constructs or using larger fusion proteins to improve solubility and/or increase particle size. Other strategies included the deconstruction of the full-length protein to target smaller soluble domains. These manipulations were often required for crystal formation to support X-ray crystallography or to circumvent lower resolution due to high noise and dynamic motions of protein subdomains. However, recent revolutions in membrane protein biochemistry and cryo-electron microscopy now provide an opportunity to solve high resolution structures of both large, >1 megadalton (MDa), and small, <100 kDa (kDa), drug targets in near-native conditions, routinely reaching resolutions around or below 3 Å. This review provides insights into how the recent advances in membrane biology and biochemistry, as well as technical advances in cryo-electron microscopy, help us to solve structures of a large variety of membrane protein groups, from small receptors to large transporters and more complex machineries.
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Affiliation(s)
- Sarah J Piper
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Rachel M Johnson
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Denise Wootten
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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30
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Structural basis for heme detoxification by an ATP-binding cassette-type efflux pump in gram-positive pathogenic bacteria. Proc Natl Acad Sci U S A 2022; 119:e2123385119. [PMID: 35767641 PMCID: PMC9271180 DOI: 10.1073/pnas.2123385119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Bacterial pathogens acquire heme from the host hemoglobin as an iron nutrient for their virulence and proliferation in blood. Concurrently, they encounter cytotoxic-free heme that escapes the heme-acquisition process. To overcome this toxicity, many gram-positive bacteria employ an ATP-binding cassette heme-dedicated efflux pump, HrtBA in the cytoplasmic membranes. Although genetic analyses have suggested that HrtBA expels heme from the bacterial membranes, the molecular mechanism of heme efflux remains elusive due to the lack of protein studies. Here, we show the biochemical properties and crystal structures of Corynebacterium diphtheriae HrtBA, alone and in complex with heme or an ATP analog, and we reveal how HrtBA extracts heme from the membrane and releases it. HrtBA consists of two cytoplasmic HrtA ATPase subunits and two transmembrane HrtB permease subunits. A heme-binding site is formed in the HrtB dimer and is laterally accessible to heme in the outer leaflet of the membrane. The heme-binding site captures heme from the membrane using a glutamate residue of either subunit as an axial ligand and sequesters the heme within the rearranged transmembrane helix bundle. By ATP-driven HrtA dimerization, the heme-binding site is squeezed to extrude the bound heme. The mechanism sheds light on the detoxification of membrane-bound heme in this bacterium.
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31
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Blair JMA, Zeth K, Bavro VN, Sancho-Vaello E. The role of bacterial transport systems in the removal of host antimicrobial peptides in Gram-negative bacteria. FEMS Microbiol Rev 2022; 46:6617596. [PMID: 35749576 PMCID: PMC9629497 DOI: 10.1093/femsre/fuac032] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/23/2022] [Accepted: 06/22/2022] [Indexed: 01/09/2023] Open
Abstract
Antibiotic resistance is a global issue that threatens our progress in healthcare and life expectancy. In recent years, antimicrobial peptides (AMPs) have been considered as promising alternatives to the classic antibiotics. AMPs are potentially superior due to their lower rate of resistance development, since they primarily target the bacterial membrane ('Achilles' heel' of the bacteria). However, bacteria have developed mechanisms of AMP resistance, including the removal of AMPs to the extracellular space by efflux pumps such as the MtrCDE or AcrAB-TolC systems, and the internalization of AMPs to the cytoplasm by the Sap transporter, followed by proteolytic digestion. In this review, we focus on AMP transport as a resistance mechanism compiling all the experimental evidence for the involvement of efflux in AMP resistance in Gram-negative bacteria and combine this information with the analysis of the structures of the efflux systems involved. Finally, we expose some open questions with the aim of arousing the interest of the scientific community towards the AMPs-efflux pumps interactions. All the collected information broadens our understanding of AMP removal by efflux pumps and gives some clues to assist the rational design of AMP-derivatives as inhibitors of the efflux pumps.
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Affiliation(s)
- Jessica M A Blair
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Kornelius Zeth
- Department of Science and Environment, Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
| | - Vassiliy N Bavro
- School of Life Sciences, University of Essex, Colchester, CO4 3SQ, United Kingdom
| | - Enea Sancho-Vaello
- Corresponding author. College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom. E-mail:
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32
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Łapińska U, Voliotis M, Lee KK, Campey A, Stone MRL, Tuck B, Phetsang W, Zhang B, Tsaneva-Atanasova K, Blaskovich MAT, Pagliara S. Fast bacterial growth reduces antibiotic accumulation and efficacy. eLife 2022; 11:74062. [PMID: 35670099 PMCID: PMC9173744 DOI: 10.7554/elife.74062] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 05/08/2022] [Indexed: 12/11/2022] Open
Abstract
Phenotypic variations between individual microbial cells play a key role in the resistance of microbial pathogens to pharmacotherapies. Nevertheless, little is known about cell individuality in antibiotic accumulation. Here, we hypothesise that phenotypic diversification can be driven by fundamental cell-to-cell differences in drug transport rates. To test this hypothesis, we employed microfluidics-based single-cell microscopy, libraries of fluorescent antibiotic probes and mathematical modelling. This approach allowed us to rapidly identify phenotypic variants that avoid antibiotic accumulation within populations of Escherichia coli, Pseudomonas aeruginosa, Burkholderia cenocepacia, and Staphylococcus aureus. Crucially, we found that fast growing phenotypic variants avoid macrolide accumulation and survive treatment without genetic mutations. These findings are in contrast with the current consensus that cellular dormancy and slow metabolism underlie bacterial survival to antibiotics. Our results also show that fast growing variants display significantly higher expression of ribosomal promoters before drug treatment compared to slow growing variants. Drug-free active ribosomes facilitate essential cellular processes in these fast-growing variants, including efflux that can reduce macrolide accumulation. We used this new knowledge to eradicate variants that displayed low antibiotic accumulation through the chemical manipulation of their outer membrane inspiring new avenues to overcome current antibiotic treatment failures.
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Affiliation(s)
- Urszula Łapińska
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - Margaritis Voliotis
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Department of Mathematics, University of ExeterExeterUnited Kingdom
| | - Ka Kiu Lee
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - Adrian Campey
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New JerseyPiscatawayUnited States
| | - Brandon Tuck
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - Wanida Phetsang
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
| | - Bing Zhang
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Department of Mathematics, University of ExeterExeterUnited Kingdom
- EPSRC Hub for Quantitative Modelling in Healthcare, University of ExeterExeterUnited Kingdom
- Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of SciencesSofiaBulgaria
| | - Mark AT Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
| | - Stefano Pagliara
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
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33
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Huang L, Wu C, Gao H, Xu C, Dai M, Huang L, Hao H, Wang X, Cheng G. Bacterial Multidrug Efflux Pumps at the Frontline of Antimicrobial Resistance: An Overview. Antibiotics (Basel) 2022; 11:antibiotics11040520. [PMID: 35453271 PMCID: PMC9032748 DOI: 10.3390/antibiotics11040520] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/01/2022] [Accepted: 04/08/2022] [Indexed: 02/06/2023] Open
Abstract
Multidrug efflux pumps function at the frontline to protect bacteria against antimicrobials by decreasing the intracellular concentration of drugs. This protective barrier consists of a series of transporter proteins, which are located in the bacterial cell membrane and periplasm and remove diverse extraneous substrates, including antimicrobials, organic solvents, toxic heavy metals, etc., from bacterial cells. This review systematically and comprehensively summarizes the functions of multiple efflux pumps families and discusses their potential applications. The biological functions of efflux pumps including their promotion of multidrug resistance, biofilm formation, quorum sensing, and survival and pathogenicity of bacteria are elucidated. The potential applications of efflux pump-related genes/proteins for the detection of antibiotic residues and antimicrobial resistance are also analyzed. Last but not least, efflux pump inhibitors, especially those of plant origin, are discussed.
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34
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A noncanonical chaperone interacts with drug efflux pumps during their assembly into bacterial outer membranes. PLoS Biol 2022; 20:e3001523. [PMID: 35061668 PMCID: PMC8809574 DOI: 10.1371/journal.pbio.3001523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 02/02/2022] [Accepted: 12/22/2021] [Indexed: 11/19/2022] Open
Abstract
Bacteria have membrane-spanning efflux pumps to secrete toxic compounds ranging from heavy metal ions to organic chemicals, including antibiotic drugs. The overall architecture of these efflux pumps is highly conserved: with an inner membrane energy-transducing subunit coupled via an adaptor protein to an outer membrane conduit subunit that enables toxic compounds to be expelled into the environment. Here, we map the distribution of efflux pumps across bacterial lineages to show these proteins are more widespread than previously recognised. Complex phylogenetics support the concept that gene cassettes encoding the subunits for these pumps are commonly acquired by horizontal gene transfer. Using TolC as a model protein, we demonstrate that assembly of conduit subunits into the outer membrane uses the chaperone TAM to physically organise the membrane-embedded staves of the conduit subunit of the efflux pump. The characteristics of this assembly pathway have impact for the acquisition of efflux pumps across bacterial species and for the development of new antimicrobial compounds that inhibit efflux pump function. A crosslinking study reveals novel insights into how the chaperone TAM helps Gram-negative bacteria insert the drug efflux pump subunit TolC into their outer membrane. Bioinformatic analyses show that TolC-like proteins can be found in all LPS-containing bacteria, but also in some monodermic Firmicutes.
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Robin B, Nicol M, Le H, Tahrioui A, Schaumann A, Vuillemenot JB, Vergoz D, Lesouhaitier O, Jouenne T, Hardouin J, Potron A, Perrot V, Dé E. MacAB-TolC Contributes to the Development of Acinetobacter baumannii Biofilm at the Solid–Liquid Interface. Front Microbiol 2022; 12:785161. [PMID: 35095797 PMCID: PMC8792954 DOI: 10.3389/fmicb.2021.785161] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/22/2021] [Indexed: 12/14/2022] Open
Abstract
Acinetobacter baumannii has emerged as one of the most problematic bacterial pathogens responsible for hospital-acquired and community infections worldwide. Besides its high capacity to acquire antibiotic resistance mechanisms, it also presents high adhesion abilities on inert and living surfaces leading to biofilm development. This lifestyle confers additional protection against various treatments and allows it to persist for long periods in various hospital niches. Due to their remarkable antimicrobial tolerance, A. baumannii biofilms are difficult to control and ultimately eradicate. Further insights into the mechanism of biofilm development will help to overcome this challenge and to develop novel antibiofilm strategies. To unravel critical determinants of this sessile lifestyle, the proteomic profiles of two A. baumannii strains (ATTC17978 and SDF) grown in planktonic stationary phase or in mature solid–liquid (S-L) biofilm were compared using a semiquantitative proteomic study. Of interest, among the 69 common proteins determinants accumulated in the two strains at the S-L interface, we sorted out the MacAB-TolC system. This tripartite efflux pump played a role in A. baumannii biofilm formation as demonstrated by using ΔmacAB-tolC deletion mutant. Complementary approaches allowed us to get an overview of the impact of macAB-tolC deletion in A. baumannii physiology. Indeed, this efflux pump appeared to be involved in the envelope stress response occurring in mature biofilm. It contributes to maintain wild type (WT) membrane rigidity and provides tolerance to high osmolarity conditions. In addition, this system is probably involved in the maintenance of iron and sulfur homeostasis. MacAB-TolC might help this pathogen face and adapt to deleterious conditions occurring in mature biofilms. Increasing our knowledge of A. baumannii biofilm formation will undoubtedly help us develop new therapeutic strategies to tackle this emerging threat to human health.
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Affiliation(s)
- Brandon Robin
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Marion Nicol
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Hung Le
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Ali Tahrioui
- Normandie Univ, UNIROUEN, LMSM EA4312, Evreux, France
| | - Annick Schaumann
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | | | - Delphine Vergoz
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | | | - Thierry Jouenne
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | - Julie Hardouin
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | - Anaïs Potron
- UMR 6249 Chrono-Environnement, CNRS-Université de Bourgogne/Franche-Comté, Besançon, France
| | - Valérie Perrot
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- *Correspondence: Valérie Perrot,
| | - Emmanuelle Dé
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- Emmanuelle Dé,
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Chen M, Shi X, Yu Z, Fan G, Serysheva II, Baker ML, Luisi BF, Ludtke SJ, Wang Z. In situ structure of the AcrAB-TolC efflux pump at subnanometer resolution. Structure 2022; 30:107-113.e3. [PMID: 34506732 PMCID: PMC8741639 DOI: 10.1016/j.str.2021.08.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/22/2021] [Accepted: 08/18/2021] [Indexed: 01/09/2023]
Abstract
The tripartite AcrAB-TolC assembly, which spans both the inner and outer membranes in Gram-negative bacteria, is an efflux pump that contributes to multidrug resistance. Here, we present the in situ structure of full-length Escherichia coli AcrAB-TolC determined at 7 Å resolution by electron cryo-tomography. The TolC channel penetrates the outer membrane bilayer through to the outer leaflet and exhibits two different configurations that differ by a 60° rotation relative to the AcrB position in the pump assembly. AcrA protomers interact directly with the inner membrane and with AcrB via an interface located in proximity to the AcrB ligand-binding pocket. Our structural analysis suggests that these AcrA-bridged interactions underlie an allosteric mechanism for transmitting drug-evoked signals from AcrB to the TolC channel within the pump. Our study demonstrates the power of in situ electron cryo-tomography, which permits critical insights into the function of bacterial efflux pumps.
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Affiliation(s)
- Muyuan Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xiaodong Shi
- Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application, Xuzhou Medical University, Xuzhou, Jiangsu 221004, China
| | - Zhili Yu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Guizhen Fan
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at the University of Texas Health Science Center, Houston, TX 77030, USA
| | - Irina I Serysheva
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at the University of Texas Health Science Center, Houston, TX 77030, USA
| | - Matthew L Baker
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at the University of Texas Health Science Center, Houston, TX 77030, USA
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Cambridge CB21GA, UK
| | - Steven J Ludtke
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhao Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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37
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Younus I, Kochkina S, Choi CC, Sun W, Ford RC. ATP-Binding Cassette Transporters: Snap-on Complexes? Subcell Biochem 2022; 99:35-82. [PMID: 36151373 DOI: 10.1007/978-3-031-00793-4_2] [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] [Indexed: 06/16/2023]
Abstract
ATP-binding cassette (ABC) transporters are one of the largest families of membrane proteins in prokaryotic organisms. Much is now understood about the structure of these transporters and many reviews have been written on that subject. In contrast, less has been written on the assembly of ABC transporter complexes and this will be a major focus of this book chapter. The complexes are formed from two cytoplasmic subunits that are highly conserved (in terms of their primary and three-dimensional structures) across the whole family. These ATP-binding subunits give rise to the name of the family. They must assemble with two transmembrane subunits that will typically form the permease component of the transporter. The transmembrane subunits have been found to be surprisingly diverse in structure when the whole family is examined, with seven distinct folds identified so far. Hence nucleotide-binding subunits appear to have been bolted on to a variety of transmembrane platforms during evolution, leading to a greater variety in function. Furthermore, many importers within the family utilise a further external substrate-binding component to trap scarce substrates and deliver them to the correct permease components. In this chapter, we will discuss whether assembly of the various ABC transporter subunits occurs with high fidelity within the crowded cellular environment and whether promiscuity in assembly of transmembrane and cytoplasmic components can occur. We also discuss the new AlphaFold protein structure prediction tool which predicts a new type of transmembrane domain fold within the ABC transporters that is associated with cation exporters of bacteria and plants.
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Affiliation(s)
- Iqra Younus
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Sofia Kochkina
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Cheri C Choi
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Wenjuan Sun
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Robert C Ford
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK.
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38
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Webber A, Ratnaweera M, Harris A, Luisi BF, Ntsogo Enguéné VY. A Model for Allosteric Communication in Drug Transport by the AcrAB-TolC Tripartite Efflux Pump. Antibiotics (Basel) 2022; 11:52. [PMID: 35052929 PMCID: PMC8773123 DOI: 10.3390/antibiotics11010052] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 01/30/2023] Open
Abstract
RND family efflux pumps are complex macromolecular machines involved in multidrug resistance by extruding antibiotics from the cell. While structural studies and molecular dynamics simulations have provided insights into the architecture and conformational states of the pumps, the path followed by conformational changes from the inner membrane protein (IMP) to the periplasmic membrane fusion protein (MFP) and to the outer membrane protein (OMP) in tripartite efflux assemblies is not fully understood. Here, we investigated AcrAB-TolC efflux pump's allostery by comparing resting and transport states using difference distance matrices supplemented with evolutionary couplings data and buried surface area measurements. Our analysis indicated that substrate binding by the IMP triggers quaternary level conformational changes in the MFP, which induce OMP to switch from the closed state to the open state, accompanied by a considerable increase in the interface area between the MFP subunits and between the OMPs and MFPs. This suggests that the pump's transport-ready state is at a more favourable energy level than the resting state, but raises the puzzle of how the pump does not become stably trapped in a transport-intermediate state. We propose a model for pump allostery that includes a downhill energetic transition process from a proposed 'activated' transport state back to the resting pump.
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Affiliation(s)
- Anya Webber
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK; (A.W.); (A.H.)
| | - Malitha Ratnaweera
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK;
| | - Andrzej Harris
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK; (A.W.); (A.H.)
| | - Ben F. Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK; (A.W.); (A.H.)
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Lomize AL, Todd SC, Pogozheva ID. Spatial arrangement of proteins in planar and curved membranes by PPM 3.0. Protein Sci 2022; 31:209-220. [PMID: 34716622 PMCID: PMC8740824 DOI: 10.1002/pro.4219] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 01/03/2023]
Abstract
Cellular protrusions, invaginations, and many intracellular organelles have strongly curved membrane regions. Transmembrane and peripheral membrane proteins that induce, sense, or stabilize such regions cannot be properly fitted into a single flat bilayer. To treat such proteins, we developed a new method and a web tool, PPM 3.0, for positioning proteins in curved or planar, single or multiple membranes. This method determines the energetically optimal spatial position, the hydrophobic thickness, and the radius of intrinsic curvature of a membrane-deforming protein structure by arranging it in a single or several sphere-shaped or planar membrane sections. In addition, it can define the lipid-embedded regions of a protein that simultaneously spans several membranes or determine the optimal position of a peptide in a spherical micelle. The PPM 3.0 web server operates with 17 types of biological membranes and 4 types of artificial bilayers. It is publicly available at https://opm.phar.umich.edu/ppm_server3. PPM 3.0 was applied to identify and characterize arrangements in membranes of 128 proteins with a significant intrinsic curvature, such as BAR domains, annexins, Piezo, and MscS mechanosensitive channels, cation-chloride cotransporters, as well as mitochondrial ATP synthases, calcium uniporters, and TOM complexes. These proteins form large complexes that are mainly localized in mitochondria, plasma membranes, and endosomes. Structures of bacterial drug efflux pumps, AcrAB-TolC, MexAB-OrpM, and MacAB-TolC, were positioned in both membranes of the bacterial cell envelop, while structures of multimeric gap-junction channels were arranged in two opposed cellular membranes.
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Affiliation(s)
- Andrei L. Lomize
- College of Pharmacy, Department of Medicinal ChemistryUniversity of MichiganAnn ArborMichiganUSA
| | - Spencer C. Todd
- Department of Electrical Engineering and Computer Science, College of EngineeringUniversity of MichiganAnn ArborMichiganUSA
| | - Irina D. Pogozheva
- College of Pharmacy, Department of Medicinal ChemistryUniversity of MichiganAnn ArborMichiganUSA
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Frozen motion: how cryo-EM changes the way we look at ABC transporters. Trends Biochem Sci 2021; 47:136-148. [PMID: 34930672 DOI: 10.1016/j.tibs.2021.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 11/29/2021] [Accepted: 11/29/2021] [Indexed: 12/18/2022]
Abstract
ATP-binding cassette (ABC) transporters are widely present molecular machines that transfer substrates across the cell membrane. ABC transporters are involved in numerous physiological processes and are often clinical targets. Structural biology is fundamental to obtain the molecular details underlying ABC transporter function and suggest approaches to modulate it. Until recently, X-ray crystallography has been the only method capable of providing high-resolution structures of ABC transporters. However, modern cryo-electron microscopy (cryo-EM) opens entirely new ways of studying these dynamic membrane proteins. Cryo-EM enables analyses of targets that resist X-ray crystallography, challenging multicomponent complexes, and the exploration of conformational dynamics. These unique capacities have turned cryo-EM into the dominant technique for structural studies of membrane proteins, including ABC transporters.
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41
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Quantification and surface localization of the hemolysin A type 1 secretion system at the endogenous level and under conditions of overexpression. Appl Environ Microbiol 2021; 88:e0189621. [PMID: 34851699 DOI: 10.1128/aem.01896-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Secretion systems are essential for Gram-negative bacteria as these nanomachineries allow a communication with the outside world by exporting proteins into the extracellular space or directly into the cytosol of a host cell. For example, type one secretion systems (T1SS) secrete a broad range of substrates across both membranes into the extracellular space. One well-known example is the hemolysin A (HlyA) T1SS from Escherichia coli (E. coli), which consists of an ABC transporter (HlyB), a membrane fusion protein (HlyD), the outer membrane protein TolC and the substrate HlyA, a member of the family of RTX (repeats in toxins) toxins. Here, we determined the amount of TolC at the endogenous level (parental strain, UTI89) and under conditions of overexpression (T7 expression system, BL21(DE3)-BD). The overall amount of TolC was not influenced by the overexpression of the HlyBD complex. Moving one step further, we determined the localization of the HlyA T1SS by super-resolution microscopy. In contrast to other bacterial secretion systems, no polarization was observed with respect to endogenous or overexpression levels. Additionally, the cell growth and division cycle did not influence the polarization. Most importantly, the size of the observed T1SS clusters did not correlate with the recently proposed outer membrane islands. These data indicate that T1SS cluster at the outer membrane generating domains of so far not described identity. Importance Uropathogenic Escherichia coli (UPEC) strains cause about 110 million urinary tract infections each year worldwide representing a global burden to the healthcare system. UPEC secrete many virulence factors among these the TX toxin hemolysin A via a cognate T1SS into the extracellular space. In this study, we determined the endogenous copy number of the HlyA T1SS in UTI89 and analyzed the surface localization in BL21(DE3)-BD and UTI89, respectively. With approximately 800 copies of the T1SS in UTI89, this is one of the highest expressed bacterial secretion systems. Furthermore and in clear contrast to other secretion systems, no polarized surface localization was detected. Finally, quantitative analysis of the super-resolution data revealed that clusters of the HlyA T1SS are not related to the recently identified outer membrane protein islands. These data provide insights into the quantitative molecular architecture of the HlyA T1SS.
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Pourhassan N Z, Smits SHJ, Ahn JH, Schmitt L. Biotechnological applications of type 1 secretion systems. Biotechnol Adv 2021; 53:107864. [PMID: 34767962 DOI: 10.1016/j.biotechadv.2021.107864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/30/2021] [Accepted: 10/31/2021] [Indexed: 02/06/2023]
Abstract
Bacteria have evolved a diverse range of secretion systems to export different substrates across their cell envelope. Although secretion of proteins into the extracellular space could offer advantages for recombinant protein production, the low secretion titers of the secretion systems for some heterologous proteins remain a clear drawback of their utility at commercial scales. Therefore, a potential use of most of secretion systems as production platforms at large scales are still limited. To overcome this limitation, remarkable efforts have been made toward improving the secretion efficiency of different bacterial secretion systems in recent years. Here, we review the progress with respect to biotechnological applications of type I secretion system (T1SS) of Gram-negative bacteria. We will also focus on the applicability of T1SS for the secretion of heterologous proteins as well as vaccine development. Last but not least, we explore the employed engineering strategies that have enhanced the secretion efficiencies of T1SS. Attention is also paid to directed evolution approaches that may offer a more versatile approach to optimize secretion efficiency of T1SS.
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Affiliation(s)
- Zohreh Pourhassan N
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Jung Hoon Ahn
- Department of Chemistry and Biology, Korea Science Academy of Korea Advanced Institute of Science and Technology, Busan 47162, South Korea
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
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Transporter Gene-mediated Typing for Detection and Genome Mining of Lipopeptide-producing Pseudomonas. Appl Environ Microbiol 2021; 88:e0186921. [PMID: 34731056 PMCID: PMC8788793 DOI: 10.1128/aem.01869-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Pseudomonas lipopeptides (LPs) are involved in diverse ecological functions and have biotechnological application potential associated with their antimicrobial and/or antiproliferative activities. They are synthesized by multimodular nonribosomal peptide synthetases which, together with transport and regulatory proteins, are encoded by large biosynthetic gene clusters (BGCs). These secondary metabolites are classified in distinct families based on the sequence and length of the oligopeptide and size of the macrocycle, if present. The phylogeny of PleB, the MacB-like transporter that is part of a dedicated ATP-dependent tripartite efflux system driving export of Pseudomonas LPs, revealed a strong correlation with LP chemical diversity. As each LP BGC carries its cognate pleB, PleB is suitable as a diagnostic sequence for genome mining, allowing assignment of the putative metabolite to a particular LP family. In addition, pleB proved to be a suitable target gene for an alternative PCR method for detecting LP-producing Pseudomonas sp. and did not rely on amplification of catalytic domains of the biosynthetic enzymes. Combined with amplicon sequencing, this approach enabled typing of Pseudomonas strains as potential producers of a LP belonging to one of the known LP families, underscoring its value for strain prioritization. This finding was validated by chemical characterization of known LPs from three different families secreted by novel producers isolated from the rice or maize rhizosphere, namely, the type strains of Pseudomonas fulva (putisolvin), Pseudomonas zeae (tensin), and Pseudomonas xantholysinigenes (xantholysin). In addition, a new member of the Bananamide family, prosekin, was discovered in the type strain of Pseudomonas prosekii, which is an Antarctic isolate. IMPORTANCEPseudomonas spp. are ubiquitous bacteria able to thrive in a wide range of ecological niches, and lipopeptides often support their lifestyle but also their interaction with other micro- and macro-organisms. Therefore, the production of lipopeptides is widespread among Pseudomonas strains. Consequently, Pseudomonas lipopeptide research not only affects chemists and microbiologists but also touches a much broader audience, including biochemists, ecologists, and plant biologists. In this study, we present a reliable transporter gene-guided approach for the detection and/or typing of Pseudomonas lipopeptide producers. Indeed, it allows us to readily assess the lipopeptide diversity among sets of Pseudomonas isolates and differentiate strains likely to produce known lipopeptides from producers of potentially novel lipopeptides. This work provides a valuable tool that can also be integrated in a genome mining strategy and adapted for the typing of other specialized metabolites.
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Sharma S, Zhou R, Wan L, Feng S, Song K, Xu C, Li Y, Liao M. Mechanism of LolCDE as a molecular extruder of bacterial triacylated lipoproteins. Nat Commun 2021; 12:4687. [PMID: 34344901 PMCID: PMC8333309 DOI: 10.1038/s41467-021-24965-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/16/2021] [Indexed: 02/07/2023] Open
Abstract
Lipoproteins are important for bacterial growth and antibiotic resistance. These proteins use lipid acyl chains attached to the N-terminal cysteine residue to anchor on the outer surface of cytoplasmic membrane. In Gram-negative bacteria, many lipoproteins are transported to the outer membrane (OM), a process dependent on the ATP-binding cassette (ABC) transporter LolCDE which extracts the OM-targeted lipoproteins from the cytoplasmic membrane. Lipid-anchored proteins pose a unique challenge for transport machinery as they have both hydrophobic lipid moieties and soluble protein component, and the underlying mechanism is poorly understood. Here we determined the cryo-EM structures of nanodisc-embedded LolCDE in the nucleotide-free and nucleotide-bound states at 3.8-Å and 3.5-Å resolution, respectively. The structural analyses, together with biochemical and mutagenesis studies, uncover how LolCDE recognizes its substrate by interacting with the lipid and N-terminal peptide moieties of the lipoprotein, and identify the amide-linked acyl chain as the key element for LolCDE interaction. Upon nucleotide binding, the transmembrane helices and the periplasmic domains of LolCDE undergo large-scale, asymmetric movements, resulting in extrusion of the captured lipoprotein. Comparison of LolCDE and MacB reveals the conserved mechanism of type VII ABC transporters and emphasizes the unique properties of LolCDE as a molecule extruder of triacylated lipoproteins.
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Affiliation(s)
- Stuti Sharma
- grid.38142.3c000000041936754XDepartment of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA USA
| | - Ruoyu Zhou
- grid.494629.40000 0004 8008 9315Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Li Wan
- grid.494629.40000 0004 8008 9315Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Shan Feng
- grid.494629.40000 0004 8008 9315Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - KangKang Song
- grid.168645.80000 0001 0742 0364Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA USA ,grid.168645.80000 0001 0742 0364Cryo-EM Core Facility, University of Massachusetts Medical School, Worcester, MA USA
| | - Chen Xu
- grid.168645.80000 0001 0742 0364Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA USA ,grid.168645.80000 0001 0742 0364Cryo-EM Core Facility, University of Massachusetts Medical School, Worcester, MA USA
| | - Yanyan Li
- grid.494629.40000 0004 8008 9315Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Maofu Liao
- grid.38142.3c000000041936754XDepartment of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA USA
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Hawley KL, Montezuma-Rusca JM, Delgado KN, Singh N, Uversky VN, Caimano MJ, Radolf JD, Luthra A. Structural Modeling of the Treponema pallidum Outer Membrane Protein Repertoire: a Road Map for Deconvolution of Syphilis Pathogenesis and Development of a Syphilis Vaccine. J Bacteriol 2021; 203:e0008221. [PMID: 33972353 PMCID: PMC8407342 DOI: 10.1128/jb.00082-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/27/2021] [Indexed: 01/11/2023] Open
Abstract
Treponema pallidum, an obligate human pathogen, has an outer membrane (OM) whose physical properties, ultrastructure, and composition differ markedly from those of phylogenetically distant Gram-negative bacteria. We developed structural models for the outer membrane protein (OMP) repertoire (OMPeome) of T. pallidum Nichols using solved Gram-negative structures, computational tools, and small-angle X-ray scattering (SAXS) of selected recombinant periplasmic domains. The T. pallidum "OMPeome" harbors two "stand-alone" proteins (BamA and LptD) involved in OM biogenesis and four paralogous families involved in the influx/efflux of small molecules: 8-stranded β-barrels, long-chain-fatty-acid transporters (FadLs), OM factors (OMFs) for efflux pumps, and T. pallidum repeat proteins (Tprs). BamA (TP0326), the central component of a β-barrel assembly machine (BAM)/translocation and assembly module (TAM) hybrid, possesses a highly flexible polypeptide-transport-associated (POTRA) 1-5 arm predicted to interact with TamB (TP0325). TP0515, an LptD ortholog, contains a novel, unstructured C-terminal domain that models inside the β-barrel. T. pallidum has four 8-stranded β-barrels, each containing positively charged extracellular loops that could contribute to pathogenesis. Three of five FadL-like orthologs have a novel α-helical, presumptively periplasmic C-terminal extension. SAXS and structural modeling further supported the bipartite membrane topology and tridomain architecture of full-length members of the Tpr family. T. pallidum's two efflux pumps presumably extrude noxious small molecules via four coexpressed OMFs with variably charged tunnels. For BamA, LptD, and OMFs, we modeled the molecular machines that deliver their substrates into the OM or external milieu. The spirochete's extended families of OM transporters collectively confer a broad capacity for nutrient uptake. The models also furnish a structural road map for vaccine development. IMPORTANCE The unusual outer membrane (OM) of T. pallidum, the syphilis spirochete, is the ultrastructural basis for its well-recognized capacity for invasiveness, immune evasion, and persistence. In recent years, we have made considerable progress in identifying T. pallidum's repertoire of OMPs. Here, we developed three-dimensional (3D) models for the T. pallidum Nichols OMPeome using structural modeling, bioinformatics, and solution scattering. The OM contains three families of OMP transporters, an OMP family involved in the extrusion of noxious molecules, and two "stand-alone" proteins involved in OM biogenesis. This work represents a major advance toward elucidating host-pathogen interactions during syphilis; understanding how T. pallidum, an extreme auxotroph, obtains a wide array of biomolecules from its obligate human host; and developing a vaccine with global efficacy.
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Affiliation(s)
- Kelly L. Hawley
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Division of Infectious Diseases and Immunology, Connecticut Children’s, Hartford, Connecticut, USA
| | - Jairo M. Montezuma-Rusca
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Division of Infectious Diseases, UConn Health, Farmington, Connecticut, USA
| | | | - Navreeta Singh
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Melissa J. Caimano
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Justin D. Radolf
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
- Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA
- Department of Immunology, UConn Health, Farmington, Connecticut, USA
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
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46
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Hüsing S, Halte M, van Look U, Guse A, Gálvez EJC, Charpentier E, Blair DF, Erhardt M, Renault TT. Control of membrane barrier during bacterial type-III protein secretion. Nat Commun 2021; 12:3999. [PMID: 34183670 PMCID: PMC8239009 DOI: 10.1038/s41467-021-24226-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 06/02/2021] [Indexed: 11/09/2022] Open
Abstract
Type-III secretion systems (T3SSs) of the bacterial flagellum and the evolutionarily related injectisome are capable of translocating proteins with a remarkable speed of several thousand amino acids per second. Here, we investigate how T3SSs are able to transport proteins at such a high rate while preventing the leakage of small molecules. Our mutational and evolutionary analyses demonstrate that an ensemble of conserved methionine residues at the cytoplasmic side of the T3SS channel create a deformable gasket (M-gasket) around fast-moving substrates undergoing export. The unique physicochemical features of the M-gasket are crucial to preserve the membrane barrier, to accommodate local conformational changes during active secretion, and to maintain stability of the secretion pore in cooperation with a plug domain (R-plug) and a network of salt-bridges. The conservation of the M-gasket, R-plug, and salt-bridge network suggests a universal mechanism by which the membrane integrity is maintained during high-speed protein translocation in all T3SSs. Type-III secretion systems (T3SSs) are capable of translocating proteins with high speed while maintaining the membrane barrier for small molecules. Here, a structure-function analysis of the T3SS pore complex elucidates the precise mechanisms enabling the gating and the conformational changes required for protein substrate secretion.
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Affiliation(s)
- Svenja Hüsing
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany.,Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | - Manuel Halte
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Ulf van Look
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany.,Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | - Alina Guse
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Eric J C Gálvez
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | | | - David F Blair
- School of Biology, University of Utah, Salt Lake City, UT, USA
| | - Marc Erhardt
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany. .,Max Planck Unit for the Science of Pathogens, Berlin, Germany.
| | - Thibaud T Renault
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany. .,Max Planck Unit for the Science of Pathogens, Berlin, Germany. .,CNRS, UMR 5234, Université de Bordeaux, Bordeaux, France. .,Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac, France.
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47
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Januliene D, Moeller A. Cryo-EM of ABC transporters: an ice-cold solution to everything? FEBS Lett 2021; 594:3776-3789. [PMID: 33156959 DOI: 10.1002/1873-3468.13989] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/28/2020] [Accepted: 10/27/2020] [Indexed: 01/10/2023]
Abstract
High-resolution cryo-EM has revolutionized how we look at ABC transporters and membrane proteins in general. An ever-increasing number of software tools and faster processing now allow dissecting the molecular details of nanomachines at atomic precision. Considering the further benefits of significantly reduced sample demands and increased speed, cryo-EM will dominate the structure determination of membrane proteins in the near future without compromising on data quality or detail. Moreover, improved and new algorithms make it now possible to resolve the conformational spectrum of macromolecular machines under turnover conditions and to analyze heterogeneous samples at high resolution. The future of cryo-EM is, therefore, bright, and the growing number of imaging facilities and groups active in this field will amplify this trend even further. Nevertheless, expectations have to be managed, as cryo-EM alone cannot provide an ultimate answer to all scientific questions. In this review, we discuss the capabilities and limitations of cryo-EM together with possible solutions for studies of ABC transporters.
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Affiliation(s)
- Dovile Januliene
- University of Osnabrück, Germany.,Max-Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Arne Moeller
- University of Osnabrück, Germany.,Max-Planck Institute of Biophysics, Frankfurt am Main, Germany
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48
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Abstract
ATP-binding cassette (ABC) transporters constitute one of the largest and most ancient protein superfamilies found in all living organisms. They function as molecular machines by coupling ATP binding, hydrolysis, and phosphate release to translocation of diverse substrates across membranes. The substrates range from vitamins, steroids, lipids, and ions to peptides, proteins, polysaccharides, and xenobiotics. ABC transporters undergo substantial conformational changes during substrate translocation. A comprehensive understanding of their inner workings thus requires linking these structural rearrangements to the different functional state transitions. Recent advances in single-particle cryogenic electron microscopy have not only delivered crucial information on the architecture of several medically relevant ABC transporters and their supramolecular assemblies, including the ATP-sensitive potassium channel and the peptide-loading complex, but also made it possible to explore the entire conformational space of these nanomachines under turnover conditions and thereby gain detailed mechanistic insights into their mode of action.
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Affiliation(s)
- Christoph Thomas
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany; ,
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany; ,
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49
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Rybenkov VV, Zgurskaya HI, Ganguly C, Leus IV, Zhang Z, Moniruzzaman M. The Whole Is Bigger than the Sum of Its Parts: Drug Transport in the Context of Two Membranes with Active Efflux. Chem Rev 2021; 121:5597-5631. [PMID: 33596653 DOI: 10.1021/acs.chemrev.0c01137] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell envelope plays a dual role in the life of bacteria by simultaneously protecting it from a hostile environment and facilitating access to beneficial molecules. At the heart of this ability lie the restrictive properties of the cellular membrane augmented by efflux transporters, which preclude intracellular penetration of most molecules except with the help of specialized uptake mediators. Recently, kinetic properties of the cell envelope came into focus driven on one hand by the urgent need in new antibiotics and, on the other hand, by experimental and theoretical advances in studies of transmembrane transport. A notable result from these studies is the development of a kinetic formalism that integrates the Michaelis-Menten behavior of individual transporters with transmembrane diffusion and offers a quantitative basis for the analysis of intracellular penetration of bioactive compounds. This review surveys key experimental and computational approaches to the investigation of transport by individual translocators and in whole cells, summarizes key findings from these studies and outlines implications for antibiotic discovery. Special emphasis is placed on Gram-negative bacteria, whose envelope contains two separate membranes. This feature sets these organisms apart from Gram-positive bacteria and eukaryotic cells by providing them with full benefits of the synergy between slow transmembrane diffusion and active efflux.
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Affiliation(s)
- Valentin V Rybenkov
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Chhandosee Ganguly
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Inga V Leus
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Zhen Zhang
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Mohammad Moniruzzaman
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
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50
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Alav I, Kobylka J, Kuth MS, Pos KM, Picard M, Blair JMA, Bavro VN. Structure, Assembly, and Function of Tripartite Efflux and Type 1 Secretion Systems in Gram-Negative Bacteria. Chem Rev 2021; 121:5479-5596. [PMID: 33909410 PMCID: PMC8277102 DOI: 10.1021/acs.chemrev.1c00055] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/11/2022]
Abstract
Tripartite efflux pumps and the related type 1 secretion systems (T1SSs) in Gram-negative organisms are diverse in function, energization, and structural organization. They form continuous conduits spanning both the inner and the outer membrane and are composed of three principal components-the energized inner membrane transporters (belonging to ABC, RND, and MFS families), the outer membrane factor channel-like proteins, and linking the two, the periplasmic adaptor proteins (PAPs), also known as the membrane fusion proteins (MFPs). In this review we summarize the recent advances in understanding of structural biology, function, and regulation of these systems, highlighting the previously undescribed role of PAPs in providing a common architectural scaffold across diverse families of transporters. Despite being built from a limited number of basic structural domains, these complexes present a staggering variety of architectures. While key insights have been derived from the RND transporter systems, a closer inspection of the operation and structural organization of different tripartite systems reveals unexpected analogies between them, including those formed around MFS- and ATP-driven transporters, suggesting that they operate around basic common principles. Based on that we are proposing a new integrated model of PAP-mediated communication within the conformational cycling of tripartite systems, which could be expanded to other types of assemblies.
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Affiliation(s)
- Ilyas Alav
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Jessica Kobylka
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Miriam S. Kuth
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Klaas M. Pos
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Martin Picard
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS
UMR 7099, Université de Paris, 75005 Paris, France
- Fondation
Edmond de Rothschild pour le développement de la recherche
Scientifique, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Jessica M. A. Blair
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Vassiliy N. Bavro
- School
of Life Sciences, University of Essex, Colchester, CO4 3SQ United Kingdom
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