1
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Rana R, Jaiswal G, Bansal K, Patil PB. Comparative genomics reveals the emergence of copper resistance in a non-pigmented Xanthomonas pathogen of grapevine. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023; 15:716-726. [PMID: 37254648 PMCID: PMC10667641 DOI: 10.1111/1758-2229.13164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 05/05/2023] [Indexed: 06/01/2023]
Abstract
Xanthomonas citri pv. viticola (Xcv) is the causal agent of bacterial canker in grapevine. The pathogen is restricted to India, where it was first reported in the 1970s, and Brazil. In the present study, we report the first complete genome sequence of Xcv LMG965, which is a reference pathotype strain. We also report genome sequences of additional isolates from India and comparative genome-based studies of isolates from Brazil. Apart from revealing the monophyletic origin of the pathovar, we could also confirm a common frameshift mutation in a gene that is part of the Xanthomonadin pigment biosynthetic gene cluster in all the isolates. The comparative study also revealed multiple intrinsic copper resistance-related genes in Brazilian isolates, suggesting intense selection, possibly because of heavy and indiscriminate usage of copper as an antimicrobial agent in the orchards. There is also the association of a Tn3-like transposase in the vicinity of the copper resistance genes, indicating a potential for rapid diversification through horizontal gene transfer events. The findings, along with genomic resources, will allow for systematic genetic and functional studies of Xcv.
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Affiliation(s)
- Rekha Rana
- Bacterial Genomics and Evolution LaboratoryCSIR‐Institute of Microbial TechnologyChandigarhIndia
- The Academy of Scientific and Innovative ResearchGhaziabadIndia
| | - Gagandeep Jaiswal
- Bacterial Genomics and Evolution LaboratoryCSIR‐Institute of Microbial TechnologyChandigarhIndia
- The Academy of Scientific and Innovative ResearchGhaziabadIndia
| | - Kanika Bansal
- Bacterial Genomics and Evolution LaboratoryCSIR‐Institute of Microbial TechnologyChandigarhIndia
| | - Prabhu B. Patil
- Bacterial Genomics and Evolution LaboratoryCSIR‐Institute of Microbial TechnologyChandigarhIndia
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2
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Zheng M, Lupoli TJ. Counteracting antibiotic resistance enzymes and efflux pumps. Curr Opin Microbiol 2023; 75:102334. [PMID: 37329679 DOI: 10.1016/j.mib.2023.102334] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/02/2023] [Accepted: 05/17/2023] [Indexed: 06/19/2023]
Abstract
Bacterial pathogens are constantly evolving new resistance mechanisms against antibiotics; hence, strategies to potentiate existing antibiotics or combat mechanisms of resistance using adjuvants are always in demand. Recently, inhibitors have been identified that counteract enzymatic modification of the drugs isoniazid and rifampin, which have implications in the study of multi-drug-resistant mycobacteria. A wealth of structural studies on efflux pumps from diverse bacteria has also fueled the design of new small-molecule and peptide-based agents to prevent the active transport of antibiotics. We envision that these findings will inspire microbiologists to apply existing adjuvants to clinically relevant resistant strains, or to use described platforms to discover novel antibiotic adjuvant scaffolds.
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Affiliation(s)
- Meng Zheng
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Tania J Lupoli
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY 10003, USA.
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3
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Kuo K, Liu J, Pavlova A, Gumbart JC. Drug Binding to BamA Targets Its Lateral Gate. J Phys Chem B 2023; 127:7509-7517. [PMID: 37587651 PMCID: PMC10476194 DOI: 10.1021/acs.jpcb.3c04501] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/30/2023] [Indexed: 08/18/2023]
Abstract
BamA, the core component of the β-barrel assembly machinery (BAM) complex, is an outer-membrane protein (OMP) in Gram-negative bacteria. Its function is to insert and fold substrate OMPs into the outer membrane (OM). Evidence suggests that BamA follows the asymmetric hybrid-barrel model where the first and last strands of BamA separate, a process known as lateral gate opening, to allow nascent substrate OMP β-strands to sequentially insert and fold through β-augmentation. Recently, multiple lead compounds that interfere with BamA's function have been identified. We modeled and then docked one of these compounds into either the extracellular loops of BamA or the open lateral gate. With the compound docked in the loops, we found that the lateral gate remains closed during 5 μs molecular dynamics simulations. The same compound when docked in the open lateral gate stays bound to the β16 strand of BamA during the simulation, which would prevent substrate OMP folding. In addition, we simulated mutants of BamA that are resistant to one or more of the identified lead compounds. In these simulations, we observed a differing degree and/or frequency of opening of BamA's lateral gate compared to BamA-apo, suggesting that the mutations grant resistance by altering the dynamics at the gate. We conclude that the compounds act by inhibiting BamA lateral gate opening and/or binding of substrate, thus preventing subsequent OMP folding and insertion.
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Affiliation(s)
- Katie
M. Kuo
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
| | - Jinchan Liu
- Department
of Molecular Biophysics and Biochemistry (MB&B), Yale University, New Haven, Connecticut 06510, United States
| | - Anna Pavlova
- School
of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - James C. Gumbart
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- School
of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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4
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D'Angelo EM. Diversity of virulence and antibiotic resistance genes expressed in Class A biosolids and biosolids-amended soil as revealed by metatranscriptomic analysis. Lett Appl Microbiol 2023; 76:ovad097. [PMID: 37596067 DOI: 10.1093/lambio/ovad097] [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: 05/26/2023] [Revised: 07/18/2023] [Accepted: 08/17/2023] [Indexed: 08/20/2023]
Abstract
Class A biosolids is a treated sewage sludge, commonly applied to agricultural fields, home lawns/gardens, golf courses, forests, and remediation sites around the world. This practice is of public and agricultural concern due to the possibility that biosolids contain antibiotic-resistant bacteria and fungal pathogens that could persist for extended periods in soil. This possibility was determined by metatranscriptomic analysis of virulence, antibiotic resistance, and plasmid conjugation genes, a Class A biosolids, organically managed soil, and biosolids-amended soil under realistic conditions. Biosolids harbored numerous transcriptionally active pathogens, antibiotic resistance genes, and conjugative genes that annotated mostly to Gram-positive pathogens of animal hosts. Biosolids amendment to soil significantly increased the expression of virulence genes by numerous pathogens and antibiotic-resistant genes that were strongly associated with biosolids. Biosolids amendment also significantly increased the expression of virulence genes by native soil fungal pathogens of plant hosts, which suggests higher risks of crop damage by soil fungal pathogens in biosolids-amended soil. Although results are likely to be different in other soils, biosolids, and microbial growth conditions, they provide a more holistic, accurate view of potential health risks associated with biosolids and biosolids-amended soils than has been achievable with more selective cultivation and PCR-based techniques.
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Affiliation(s)
- Elisa Marie D'Angelo
- Plant and Soil Sciences Department, University of Kentucky, N-122 Agricultural Science Center North, Lexington, KY 40546, United States
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5
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Lin Y, Shi J, Feng W, Yue J, Luo Y, Chen S, Yang B, Jiang Y, Hu H, Zhou C, Shi F, Prominski A, Talapin DV, Xiong W, Gao X, Tian B. Periplasmic biomineralization for semi-artificial photosynthesis. SCIENCE ADVANCES 2023; 9:eadg5858. [PMID: 37478187 PMCID: PMC10361601 DOI: 10.1126/sciadv.adg5858] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Accepted: 06/21/2023] [Indexed: 07/23/2023]
Abstract
Semiconductor-based biointerfaces are typically established either on the surface of the plasma membrane or within the cytoplasm. In Gram-negative bacteria, the periplasmic space, characterized by its confinement and the presence of numerous enzymes and peptidoglycans, offers additional opportunities for biomineralization, allowing for nongenetic modulation interfaces. We demonstrate semiconductor nanocluster precipitation containing single- and multiple-metal elements within the periplasm, as observed through various electron- and x-ray-based imaging techniques. The periplasmic semiconductors are metastable and display defect-dominant fluorescent properties. Unexpectedly, the defect-rich (i.e., the low-grade) semiconductor nanoclusters produced in situ can still increase adenosine triphosphate levels and malate production when coupled with photosensitization. We expand the sustainability levels of the biohybrid system to include reducing heavy metals at the primary level, building living bioreactors at the secondary level, and creating semi-artificial photosynthesis at the tertiary level. The biomineralization-enabled periplasmic biohybrids have the potential to serve as defect-tolerant platforms for diverse sustainable applications.
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Affiliation(s)
- Yiliang Lin
- The James Franck Institute, University of Chicago, Chicago, IL 60637, USA
| | - Jiuyun Shi
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Wei Feng
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, and Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518000, China
| | - Jiping Yue
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Yanqi Luo
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Si Chen
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Bin Yang
- Bioscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Yuanwen Jiang
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Huicheng Hu
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Chenkun Zhou
- The James Franck Institute, University of Chicago, Chicago, IL 60637, USA
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Fengyuan Shi
- Electron Microscopy Core, University of Illinois Chicago, Chicago, IL 60607, USA
| | | | - Dmitri V. Talapin
- The James Franck Institute, University of Chicago, Chicago, IL 60637, USA
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - Wei Xiong
- Bioscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Xiang Gao
- The James Franck Institute, University of Chicago, Chicago, IL 60637, USA
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, and Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518000, China
| | - Bozhi Tian
- The James Franck Institute, University of Chicago, Chicago, IL 60637, USA
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
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6
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Bonn CM, Rafiqullah IM, Crawford JA, Qian YM, Guthrie JL, Matuszewska M, Robinson DA, McGavin MJ. Repeated Emergence of Variant TetR Family Regulator, FarR, and Increased Resistance to Antimicrobial Unsaturated Fatty Acid among Clonal Complex 5 Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2023; 67:e0074922. [PMID: 36744906 PMCID: PMC10019231 DOI: 10.1128/aac.00749-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Resistance-nodulation-division (RND) superfamily efflux pumps promote antibiotic resistance in Gram-negative pathogens, but their role in Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) is undocumented. However, recent in vitro selections for resistance of S. aureus to an antimicrobial fatty acid, linoleic acid, and an antibiotic, rhodomyrtone, identified H121Y and C116R substitution variants, respectively, in a TetR family regulator, FarR, promoting increased expression of the RND pump FarE. Hypothesizing that in vivo selection pressures have also promoted the emergence of FarR variants, we searched available genome data and found that strains with FarRH121Y from human and bovine hosts have emerged sporadically in clonal complexes (CCs) CC1, CC30, CC8, CC22, and CC97, whereas multiple FarR variants have occurred within CC5 hospital-associated (HA)-MRSA. Of these, FarRE160G and FarRE93EE were exclusive to CC5, while FarRC116Y, FarRP165L, and FarRG166D also occurred in nonrelated CCs, primarily from bovine hosts. Within CC5, FarRC116Y and FarRG166D strains were polyphyletic, each exhibiting two emergence events. FarRC116Y and FarRE160G were individually sufficient to confer increased expression of FarE and enhanced resistance to linoleic acid (LA). Isolates with FarRE93EE were most closely related to S. aureus N315 MRSA and exhibited increased resistance independently of FarRE93EE. Accumulation of pseudogenes and additional polymorphisms in FarRE93EE strains contributed to a multiresistance phenotype which included fosfomycin and fusidic acid resistance in addition to increased linoleic acid resistance. These findings underscore the remarkable adaptive capacity of CC5 MRSA, which includes the polyphyletic USA100 lineage of HA-MRSA that is endemic in the Western hemisphere and known for the acquisition of multiple resistance phenotypes.
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Affiliation(s)
- Camryn M. Bonn
- Department of Microbiology, University of Western Ontario, London, Ontario, Canada
| | - Iftekhar M. Rafiqullah
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - John A. Crawford
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Yi Meng Qian
- Department of Microbiology, University of Western Ontario, London, Ontario, Canada
| | - Jennifer L. Guthrie
- Department of Microbiology, University of Western Ontario, London, Ontario, Canada
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Marta Matuszewska
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - D. Ashley Robinson
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi, USA
- Center for Immunology and Microbial Research, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Martin J. McGavin
- Department of Microbiology, University of Western Ontario, London, Ontario, Canada
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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7
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Guardia AE, Wagner A, Busalmen JP, Di Capua C, Cortéz N, Beligni MV. The draft genome of Andean Rhodopseudomonas sp. strain AZUL predicts genome plasticity and adaptation to chemical homeostasis. BMC Microbiol 2022; 22:297. [PMID: 36494611 PMCID: PMC9733117 DOI: 10.1186/s12866-022-02685-w] [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: 07/07/2021] [Accepted: 10/29/2022] [Indexed: 12/13/2022] Open
Abstract
The genus Rhodopseudomonas comprises purple non-sulfur bacteria with extremely versatile metabolisms. Characterization of several strains revealed that each is a distinct ecotype highly adapted to its specific micro-habitat. Here we present the sequencing, genomic comparison and functional annotation of AZUL, a Rhodopseudomonas strain isolated from a high altitude Andean lagoon dominated by extreme conditions and fluctuating levels of chemicals. Average nucleotide identity (ANI) analysis of 39 strains of this genus showed that the genome of AZUL is 96.2% identical to that of strain AAP120, which suggests that they belong to the same species. ANI values also show clear separation at the species level with the rest of the strains, being more closely related to R. palustris. Pangenomic analyses revealed that the genus Rhodopseudomonas has an open pangenome and that its core genome represents roughly 5 to 12% of the total gene repertoire of the genus. Functional annotation showed that AZUL has genes that participate in conferring genome plasticity and that, in addition to sharing the basal metabolic complexity of the genus, it is also specialized in metal and multidrug resistance and in responding to nutrient limitation. Our results also indicate that AZUL might have evolved to use some of the mechanisms involved in resistance as redox reactions for bioenergetic purposes. Most of those features are shared with strain AAP120, and mainly involve the presence of additional orthologs responsible for the mentioned processes. Altogether, our results suggest that AZUL, one of the few bacteria from its habitat with a sequenced genome, is highly adapted to the extreme and changing conditions that constitute its niche.
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Affiliation(s)
- Aisha E. Guardia
- grid.473319.b0000 0004 0461 9871Ingeniería de Interfases y Bioprocesos, Instituto de Tecnología de Materiales (INTEMA-CONICET-UNMdP), Mar del Plata, Argentina
| | - Agustín Wagner
- grid.10814.3c0000 0001 2097 3211Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Juan P. Busalmen
- grid.473319.b0000 0004 0461 9871Ingeniería de Interfases y Bioprocesos, Instituto de Tecnología de Materiales (INTEMA-CONICET-UNMdP), Mar del Plata, Argentina
| | - Cecilia Di Capua
- grid.501777.30000 0004 0638 1836Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET-UNR), Universidad Nacional de Rosario, Rosario, Argentina
| | - Néstor Cortéz
- grid.501777.30000 0004 0638 1836Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET-UNR), Universidad Nacional de Rosario, Rosario, Argentina
| | - María V. Beligni
- grid.412221.60000 0000 9969 0902Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
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8
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Dey S, Shahrear S, Afroj Zinnia M, Tajwar A, Islam ABMMK. Functional Annotation of Hypothetical Proteins From the Enterobacter cloacae B13 Strain and Its Association With Pathogenicity. Bioinform Biol Insights 2022; 16:11779322221115535. [PMID: 35958299 PMCID: PMC9358594 DOI: 10.1177/11779322221115535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/11/2022] [Indexed: 11/25/2022] Open
Abstract
Enterobacter cloacae B13 strain is a rod-shaped gram-negative bacterium that belongs to the Enterobacteriaceae family. It can cause respiratory and urinary tract infections, and is responsible for several outbreaks in hospitals. E. cloacae has become an important pathogen and an emerging global threat because of its opportunistic and multidrug resistant ability. However, little knowledge is present about a large portion of its proteins and functions. Therefore, functional annotation of the hypothetical proteins (HPs) can provide an improved understanding of this organism and its virulence activity. The workflow in the study included several bioinformatic tools which were utilized to characterize functions, family and domains, subcellular localization, physiochemical properties, and protein-protein interactions. The E. cloacae B13 strain has overall 604 HPs, among which 78 were functionally annotated with high confidence. Several proteins were identified as enzymes, regulatory, binding, and transmembrane proteins with essential functions. Furthermore, 23 HPs were predicted to be virulent factors. These virulent proteins are linked to pathogenesis with their contribution to biofilm formation, quorum sensing, 2-component signal transduction or secretion. Better knowledge about the HPs’ characteristics and functions will provide a greater overview of the proteome. Moreover, it will help against E. cloacae in neonatal intensive care unit (NICU) outbreaks and nosocomial infections.
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Affiliation(s)
- Supantha Dey
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Sazzad Shahrear
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | | | - Ahnaf Tajwar
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
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Wan X, Li Q, Olsen RH, Meng H, Zhang Z, Wang J, Zheng H, Li L, Shi L. Engineering a CRISPR interference system targeting AcrAB-TolC efflux pump to prevent multidrug resistance development in Escherichia coli. J Antimicrob Chemother 2022; 77:2158-2166. [PMID: 35642356 DOI: 10.1093/jac/dkac166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/06/2022] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVES We engineered a CRISPR interference (CRISPRi) system targeting the AcrAB-TolC efflux pump to prevent MDR development in Escherichia coli. METHODS Nine specific single-guide RNAs (sgRNAs) were designed to target the components of the AcrAB-TolC efflux pump, namely AcrA, AcrB and TolC. A total of thirteen CRISPRi recombinant plasmids were constructed with single or clustered sgRNAs. The transcriptional levels of the target genes, MICs of multiple antibiotics and biofilm formation in each CRISPRi strain were tested. RESULTS The CRISPRi system expressing sgRNA clusters targeting acrB and tolC simultaneously exhibited the highest inhibitory effect on AcrAB-TolC efflux pump activity in E. coli HB101, with 78.3%, 90.0% and 65.4% inhibition rates on the transcriptional levels of acrA, acrB and tolC, respectively. The CRISPRi system resulted in ∼2-, ∼8- and 16-fold increased susceptibility to rifampicin, erythromycin and tetracycline, respectively. In addition, the constructed CRISPRi system reduced biofilm formation with inhibition rates in the range of 11.2% to 58.2%. CONCLUSIONS To the best of our knowledge, this is the first report on the construction of an inducible CRISPRi system targeting the AcrAB-TolC efflux pump to prevent MDR development in E. coli. This study provides insights for future regulation and manipulation of AcrAB-TolC activity and bacterial MDR by a CRISPRi system.
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Affiliation(s)
- Xiulin Wan
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China
| | - Qingyang Li
- College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Rikke Heidemann Olsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Hecheng Meng
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong, China
| | - Zhigang Zhang
- State Key Laboratory of Food Safety Technology for Meat Products, Xiamen Yinxiang Group, Xiamen, China
| | - Junlin Wang
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China
| | - Hanyu Zheng
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China
| | - Lili Li
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China
| | - Lei Shi
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China.,State Key Laboratory of Food Safety Technology for Meat Products, Xiamen Yinxiang Group, Xiamen, China
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10
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Antimicrobial resistance in Campylobacter coli and Campylobacter jejuni from human campylobacteriosis in Taiwan, 2016-2019. Antimicrob Agents Chemother 2021; 66:e0173621. [PMID: 34748382 DOI: 10.1128/aac.01736-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Campylobacter coli and C. jejuni are highly resistant to most therapeutic antimicrobials in Taiwan, rapid diagnostics of resistance in bacterial isolates is crucial for the treatment of campylobacteriosis. We characterized 219 (40 C. coli and 179 C. jejuni) isolates recovered from humans between 2016 and 2019 using whole-genome sequencing to investigate the genetic diversity among isolates and the genetic resistance determinants associated with antimicrobial resistance. Susceptibility testing with 8 antimicrobials was conducted to assess the concordance between phenotypic resistance and genetic determinants. The conventional and core genome multilocus sequence typing analysis revealed diverse clonality among the isolates. Mutations in gyrA (T86I, D90N), rpsL (K43R, K88R), and 23S rRNA (A2075G) were found in 91.8%, 3.2%, and 6.4% of the isolates, respectively. Horizontally transferable resistance genes ant(6)-I, aad9, aph(3')-IIIa, aph(2"), blaOXA, catA/fexA, cfr(C), erm(B), lnu, sat4, and tet were identified in 24.2%, 21.5%, 33.3%, 11.9%, 96.3%, 10.0%, 0.9%, 6.8%, 3.2%, 13.2%, and 96.3%, respectively. High-level resistance to 8 antimicrobials in isolates was 100% predictable by the known resistance determinants, whereas low-level resistance to azithromycin, clindamycin, nalidixic acid, ciprofloxacin, and florfenicol in isolates was associated with sequence variations in CmeA and CmeB of the CmeABC efflux pump. Resistance-enhancing CmeB variants were identified in 62.1% (136/219) of isolates. In conclusion, an extremely high proportion of C. coli (100%) and C. jejuni (88.3%) were multidrug-resistant and a high proportion (62.5%) of C. coli isolates had been resistant to azithromycin, erythromycin, and clindamycin that would complicate the treatment of invasive campylobacteriosis in this country.
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11
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Gumbart JC, Ferreira JL, Hwang H, Hazel AJ, Cooper CJ, Parks JM, Smith JC, Zgurskaya HI, Beeby M. Lpp positions peptidoglycan at the AcrA-TolC interface in the AcrAB-TolC multidrug efflux pump. Biophys J 2021; 120:3973-3982. [PMID: 34411576 DOI: 10.1016/j.bpj.2021.08.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 07/02/2021] [Accepted: 08/11/2021] [Indexed: 01/07/2023] Open
Abstract
The multidrug efflux pumps of Gram-negative bacteria are a class of complexes that span the periplasm, coupling both the inner and outer membranes to expel toxic molecules. The best-characterized example of these tripartite pumps is the AcrAB-TolC complex of Escherichia coli. However, how the complex interacts with the peptidoglycan (PG) cell wall, which is anchored to the outer membrane (OM) by Braun's lipoprotein (Lpp), is still largely unknown. In this work, we present molecular dynamics simulations of a complete, atomistic model of the AcrAB-TolC complex with the inner membrane, OM, and PG layers all present. We find that the PG localizes to the junction of AcrA and TolC, in agreement with recent cryo-tomography data. Free-energy calculations reveal that the positioning of PG is determined by the length and conformation of multiple Lpp copies anchoring it to the OM. The distance between the PG and OM measured in cryo-electron microscopy images of wild-type E. coli also agrees with the simulation-derived spacing. Sequence analysis of AcrA suggests a conserved role for interactions with PG in the assembly and stabilization of efflux pumps, one that may extend to other trans-envelope complexes as well.
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Affiliation(s)
- James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia.
| | - Josie L Ferreira
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Hyea Hwang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Anthony J Hazel
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia
| | - Connor J Cooper
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Jerry M Parks
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Jeremy C Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma
| | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, United Kingdom
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12
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Islam MT, Nasreen T, Kirchberger PC, Liang KYH, Orata FD, Johura FT, Hussain NAS, Im MS, Tarr CL, Alam M, Boucher YF. Population Analysis of Vibrio cholerae in Aquatic Reservoirs Reveals a Novel Sister Species ( Vibrio paracholerae sp. nov.) with a History of Association with Humans. Appl Environ Microbiol 2021; 87:e0042221. [PMID: 34132593 PMCID: PMC8357300 DOI: 10.1128/aem.00422-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/04/2021] [Indexed: 12/12/2022] Open
Abstract
Most efforts to understand the biology of Vibrio cholerae have focused on a single group, the pandemic-generating lineage harboring the strains responsible for all known cholera pandemics. Consequently, little is known about the diversity of this species in its native aquatic environment. To understand the differences in the V. cholerae populations inhabiting regions with a history of cholera cases and those lacking such a history, a comparative analysis of population composition was performed. Little overlap was found in lineage compositions between those in Dhaka, Bangladesh (where cholera is endemic), located in the Ganges Delta, and those in Falmouth, MA (no known history of cholera), a small coastal town on the United States east coast. The most striking difference was the presence of a group of related lineages at high abundance in Dhaka, which was completely absent from Falmouth. Phylogenomic analysis revealed that these lineages form a cluster at the base of the phylogeny for the V. cholerae species and were sufficiently differentiated genetically and phenotypically to form a novel species. A retrospective search revealed that strains from this species have been anecdotally found from around the world and were isolated as early as 1916 from a British soldier in Egypt suffering from choleraic diarrhea. In 1935, Gardner and Venkatraman unofficially referred to a member of this group as Vibrio paracholerae. In recognition of this earlier designation, we propose the name Vibrio paracholerae sp. nov. for this bacterium. Genomic analysis suggests a link with human populations for this novel species and substantial interaction with its better-known sister species. IMPORTANCE Cholera continues to remain a major public health threat around the globe. Understanding the ecology, evolution, and environmental adaptation of the causative agent (Vibrio cholerae) and tracking the emergence of novel lineages with pathogenic potential are essential to combat the problem. In this study, we investigated the population dynamics of Vibrio cholerae in an inland locality, which is known as endemic for cholera, and compared them with those of a cholera-free coastal location. We found the consistent presence of the pandemic-generating lineage of V. cholerae in Dhaka, where cholera is endemic, and an exclusive presence of a lineage phylogenetically distinct from other V. cholerae lineages. Our study suggests that this lineage represents a novel species that has pathogenic potential and a human link to its environmental abundance. The possible association with human populations and coexistence and interaction with toxigenic V. cholerae in the natural environment make this potential human pathogen an important subject for future studies.
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Affiliation(s)
| | - Tania Nasreen
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Paul C. Kirchberger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
| | - Kevin Y. H. Liang
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Fabini D. Orata
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Fatema-Tuz Johura
- Infectious Diseases Division, International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Nora A. S. Hussain
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Monica S. Im
- National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Cheryl L. Tarr
- National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Munirul Alam
- Infectious Diseases Division, International Centre for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Yann F. Boucher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore
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13
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Xu Q, Hu X, Wang Y. Alternatives to Conventional Antibiotic Therapy: Potential Therapeutic Strategies of Combating Antimicrobial-Resistance and Biofilm-Related Infections. Mol Biotechnol 2021; 63:1103-1124. [PMID: 34309796 DOI: 10.1007/s12033-021-00371-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/08/2021] [Indexed: 12/14/2022]
Abstract
Antibiotics have been denoted as the orthodox therapeutic agents for fighting bacteria-related infections in clinical practices for decades. Nevertheless, overuse of antibiotics has led to the upsurge of species with antimicrobial resistance (AMR) or multi-drug resistance. Bacteria can also grow into the biofilm, which accounts for at least two-thirds of infections. Distinct gene expression and self-produced heterogeneous hydrated extracellular polymeric substance matrix architecture of biofilm contribute to their tolerance and externally manifest as antibiotic resistance. In this review, the difficulties in combating biofilm formation and AMR are introduced, and novel alternatives to antibiotics such as metal nanoparticles and quaternary ammonium compounds, chitosan and its derivatives, antimicrobial peptides, stimuli-responsive materials, phage therapy and other therapeutic strategies, from compounds to hydrogel, from inorganic to biological, are discussed. We expect to provide useful information for the readers who are seeking for solutions to the problem of AMR and biofilm-related infections.
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Affiliation(s)
- Qian Xu
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, Sichuan, People's Republic of China
| | - Xuefeng Hu
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, Sichuan, People's Republic of China.
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, Sichuan, People's Republic of China.
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14
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Luo YH, Lai YS, Zheng C, Ilhan ZE, Ontiveros-Valencia A, Long X, Krajmalnik-Brown R, Rittmann BE. Increased expression of antibiotic-resistance genes in biofilm communities upon exposure to cetyltrimethylammonium bromide (CTAB) and other stress conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 765:144264. [PMID: 33418325 DOI: 10.1016/j.scitotenv.2020.144264] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/12/2020] [Accepted: 11/28/2020] [Indexed: 06/12/2023]
Abstract
Quaternary ammonium compounds (QAC, e.g., cetyltrimethylammonium bromide, (CTAB)) are widely used as surfactants and disinfectants. QAC already are commonly found in wastewaters, and their concentration could increase, since QAC are recommended to inactivate the SARS-CoV-2 (COVID-19) virus. Exposure of bacteria to QAC can lead to proliferation of antibiotic resistance genes (ARG). In particular, O2-based membrane biofilm reactors (O2-MBfRs) achieved excellent CTAB biodegradation, but ARG increased in their biofilms. Here, we applied meta-transcriptomic analyses to assess the impacts of CTAB exposure and operating conditions on microbial community's composition and ARG expression in the O2-MBfRs. Two opportunistic pathogens, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, dominated the microbial communities and were associated with the presence of ARG. Operating conditions that imposed stress on the biofilms, i.e., limited supplies of O2 and nitrogen or a high loading of CTAB, led to large increases in ARG expression, particularly for genes conferring antibiotic-target protection. Important within the efflux pumps was the Resistance-Nodulation-Division (RND) family, which may have been active in exporting CTAB from cells. Oxidative stress appeared to be the key factor that triggered ARG proliferation by selecting intrinsically resistant species and accentuating the expression of ARG. Our findings suggest that means to mitigate the spread of ARG, such as shown here in a O2-based membrane biofilm reactor, need to consider the impacts of stressors, including QAC exposure and stressful operating conditions.
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Affiliation(s)
- Yi-Hao Luo
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA
| | - YenJung Sean Lai
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA.
| | - Chenwei Zheng
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA
| | - Zehra Esra Ilhan
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA; INRAE, Micalis Institute, Université Paris-Saclay, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Aura Ontiveros-Valencia
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA; Division de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa de San José 2055, ZC 78216 San Luis Potosí, Mexico
| | - Xiangxing Long
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-5306, USA
| | - Rosa Krajmalnik-Brown
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA
| | - Bruce E Rittmann
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA
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15
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Yadav S, Singh AK, Agrahari AK, Pandey AK, Gupta MK, Chakravortty D, Tiwari VK, Prakash P. Galactose-Clicked Curcumin-Mediated Reversal of Meropenem Resistance among Klebsiella pneumoniae by Targeting Its Carbapenemases and the AcrAB-TolC Efflux System. Antibiotics (Basel) 2021; 10:388. [PMID: 33916608 PMCID: PMC8066637 DOI: 10.3390/antibiotics10040388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 03/30/2021] [Accepted: 04/02/2021] [Indexed: 11/16/2022] Open
Abstract
In over eighty years, despite successive antibiotics discoveries, the rapid advent of multidrug resistance among bacterial pathogens has jolted our misapprehension of success over them. Resistance is spreading faster than the discovery of new antibiotics/antimicrobials. Therefore, the search for better antimicrobials/additives becomes prudent. A water-soluble curcumin derivative (Curaq) was synthesised, employing a Cu (I) catalysed 1, 3-cyclo addition reaction; it has been evaluated as a potential treatment for multidrug-resistant isolates and as an antibiotic adjuvant for meropenem against hypervirulent multidrug-resistant Klebsiella pneumoniae isolates. We also investigated its solubility and effect over carbapenemase activity. Additionally, we investigated its impact on the AcrAB-TolC system. We found that Curaq inhibited bacterial growth at a minimal concentration of 16 µg/mL; at a 32 µg/mL concentration, it killed bacterial growth completely. Only nine (9.4%) Klebsiella isolates were sensitive to meropenem; however, after synergising with Curaq (8 µg/mL), 85 (88.54%) hvKP isolates became sensitive to the drug. The Curaq also inhibited the AcrAB-TolC efflux system at 1 µg/mL concentration by disrupting the membrane potential and causing depolarisation. The kinetic parameters obtained also indicated its promise as a carbapenemase inhibitor. These results suggest that Curaq can be an excellent drug candidate as a broad-spectrum antibacterial and anti-efflux agent.
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Affiliation(s)
- Shivangi Yadav
- Bacterial Biofilm and Drug Resistance Research Laboratory, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India; (S.Y.); (A.K.S.); (M.K.G.)
| | - Ashish Kumar Singh
- Bacterial Biofilm and Drug Resistance Research Laboratory, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India; (S.Y.); (A.K.S.); (M.K.G.)
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru 560012, India;
| | - Anand K. Agrahari
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India;
| | - Akhilesh Kumar Pandey
- Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India;
| | - Munesh Kumar Gupta
- Bacterial Biofilm and Drug Resistance Research Laboratory, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India; (S.Y.); (A.K.S.); (M.K.G.)
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru 560012, India;
- Center for Biosystem Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Vinod Kumar Tiwari
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India;
| | - Pradyot Prakash
- Bacterial Biofilm and Drug Resistance Research Laboratory, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India; (S.Y.); (A.K.S.); (M.K.G.)
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16
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Gaeta NC, Bean E, Miles AM, de Carvalho DUOG, Alemán MAR, Carvalho JS, Gregory L, Ganda E. A Cross-Sectional Study of Dairy Cattle Metagenomes Reveals Increased Antimicrobial Resistance in Animals Farmed in a Heavy Metal Contaminated Environment. Front Microbiol 2020; 11:590325. [PMID: 33304338 PMCID: PMC7701293 DOI: 10.3389/fmicb.2020.590325] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 10/16/2020] [Indexed: 12/17/2022] Open
Abstract
The use of heavy metals in economic and social development can create an accumulation of toxic waste in the environment. High concentrations of heavy metals can damage human and animal health, lead to the development of antibiotic resistance, and possibly change in bovine microbiota. It is important to investigate the influence of heavy metals in food systems to determine potential harmful effects environmental heavy metal contamination on human health. Because of a mining dam rupture, 43 million cubic meters of iron ore waste flowed into the Doce river basin surrounding Mariana City, Brazil, in 2015. Following this environmental disaster, we investigated the consequences of long-term exposure to contaminated drinking water on the microbiome and resistome of dairy cattle. We identified bacterial antimicrobial resistance (AMR) genes in the feces, rumen fluid, and nasopharynx of 16 dairy cattle 4 years after the environmental disaster. Cattle had been continuously exposed to heavy metal contaminated water until sample collection (A) and compared them to analogous samples from 16 dairy cattle in an unaffected farm, 356 km away (B). The microbiome and resistome of farm A and farm B differed in many aspects. The distribution of genes present in the cattle's nasopharynx, rumen, and feces conferring AMR was highly heterogeneous, and most genes were present in only a few samples. The relative abundance and prevalence (presence/absence) of AMR genes were higher in farm A than in farm B. Samples from farm A had a higher prevalence (presence) of genes conferring resistance to multiple drugs, metals, biocides, and multi-compound resistance. Fecal samples had a higher relative abundance of AMR genes, followed by rumen fluid samples, and the nasopharynx had the lowest relative abundance of AMR genes detected. Metagenome functional annotation suggested that selective pressures of heavy metal exposure potentially skewed pathway diversity toward fewer, more specialized functions. This is the first study that evaluates the consequences of a Brazilian environmental accident with mining ore dam failure in the microbiome of dairy cows. Our findings suggest that the long-term persistence of heavy metals in the environment may result in differences in the microbiota and enrichment of antimicrobial-resistant bacteria. Our results also suggest that AMR genes are most readily detected in fecal samples compared to rumen and nasopharyngeal samples which had relatively lower bacterial read counts. Since heavy metal contamination has an effect on the animal microbiome, environmental management is warranted to protect the food system from hazardous consequences.
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Affiliation(s)
- Natalia Carrillo Gaeta
- Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Emily Bean
- Department of Animal Science, College of Agricultural Sciences, Pennsylvania State University, State College, PA, United States
- Intercollege Graduate Degree Program in Integrative and Biomedical Physiology, Pennsylvania State University, State College, PA, United States
| | - Asha Marie Miles
- Department of Animal Science, College of Agricultural Sciences, Pennsylvania State University, State College, PA, United States
| | | | - Mario Augusto Reyes Alemán
- Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Jeferson Silva Carvalho
- Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Lilian Gregory
- Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Erika Ganda
- Department of Animal Science, College of Agricultural Sciences, Pennsylvania State University, State College, PA, United States
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17
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Duggal Y, Fontaine BM, Dailey DM, Ning G, Weinert EE. RNase I Modulates Escherichia coli Motility, Metabolism, and Resistance. ACS Chem Biol 2020; 15:1996-2004. [PMID: 32551492 DOI: 10.1021/acschembio.0c00390] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacteria are constantly adapting to their environment by sensing extracellular factors that trigger production of intracellular signaling molecules, known as second messengers. Recently, 2',3'-cyclic nucleotide monophosphates (2',3'-cNMPs) were identified in Escherichia coli and have emerged as possible novel signaling molecules. 2',3'-cNMPs are produced through endonucleolytic cleavage of short RNAs by the T2 endoribonuclease, RNase I; however, the physiological roles of RNase I remain unclear. Our transcriptomic analysis suggests that RNase I is involved in modulating numerous cellular processes, including nucleotide metabolism, motility, acid sensitivity, metal homeostasis, and outer membrane morphology. Through a combination of deletion strain and inhibitor studies, we demonstrate that RNase I plays a previously unknown role in E. coli stress resistance by affecting pathways that are part of the defense mechanisms employed by bacteria when introduced to external threats, including antibiotics. Thus, this work provides insight into the emerging roles of RNase I in bacterial signaling and physiology and highlights the potential of RNase I as a target for antibacterial adjuvants.
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Affiliation(s)
- Yashasvika Duggal
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Benjamin M. Fontaine
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Deanna M. Dailey
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Gang Ning
- Microscopy Facility, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Emily E. Weinert
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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18
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Mechanical stress compromises multicomponent efflux complexes in bacteria. Proc Natl Acad Sci U S A 2019; 116:25462-25467. [PMID: 31772020 DOI: 10.1073/pnas.1909562116] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Physical forces have a profound effect on growth, morphology, locomotion, and survival of organisms. At the level of individual cells, the role of mechanical forces is well recognized in eukaryotic physiology, but much less is known about prokaryotic organisms. Recent findings suggest an effect of physical forces on bacterial shape, cell division, motility, virulence, and biofilm initiation, but it remains unclear how mechanical forces applied to a bacterium are translated at the molecular level. In Gram-negative bacteria, multicomponent protein complexes can form rigid links across the cell envelope and are therefore subject to physical forces experienced by the cell. Here we manipulate tensile and shear mechanical stress in the bacterial cell envelope and use single-molecule tracking to show that octahedral shear (but not hydrostatic) stress within the cell envelope promotes disassembly of the tripartite efflux complex CusCBA, a system used by Escherichia coli to resist copper and silver toxicity. By promoting disassembly of this protein complex, mechanical forces within the cell envelope make the bacteria more susceptible to metal toxicity. These findings demonstrate that mechanical forces can inhibit the function of cell envelope protein assemblies in bacteria and suggest the possibility that other multicomponent, transenvelope efflux complexes may be sensitive to mechanical forces including complexes involved in antibiotic resistance, cell division, and translocation of outer membrane components. By modulating the function of proteins within the cell envelope, mechanical stress has the potential to regulate multiple processes required for bacterial survival and growth.
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19
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Hazel AJ, Abdali N, Leus IV, Parks JM, Smith JC, Zgurskaya HI, Gumbart JC. Conformational Dynamics of AcrA Govern Multidrug Efflux Pump Assembly. ACS Infect Dis 2019; 5:1926-1935. [PMID: 31517484 DOI: 10.1021/acsinfecdis.9b00273] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Multidrug efflux pumps of pathogenic, Gram-negative bacteria comprise an innate resistance mechanism and are key contributors to the emerging global pandemic of antibiotic resistance. Several increasingly detailed cryo-electron microscopy maps have been resolved of an entire efflux pump complex, AcrAB-TolC, resulting in atomistic structural models. Using a recent model, we have carried out nearly 40 μs of molecular dynamics simulations to study one of the key components of the protein complex AcrA, the membrane fusion protein that connects the inner-membrane-bound AcrB to the outer-membrane-bound TolC. We determined a three-dimensional potential of mean force (PMF) for AcrA, which displays two main conformational basins representing assembly competent and incompetent states. Corresponding experiments show that stabilizing mutations at an interdomain interface shift the dynamic equilibrium between these states to the incompetent one, disrupting pump assembly and function and resensitizing bacteria to existing antibiotics. The modulation of AcrA dynamics through pharmacological intervention therefore presents a promising route for the development of new antibiotics.
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Affiliation(s)
- Anthony J. Hazel
- School of Physics, Georgia Institute of Technology, 837 State Street NW, Atlanta, Georgia 30332, United States
| | - Narges Abdali
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Inga V. Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Jerry M. Parks
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Jeremy C. Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, 1311 Cumberland Avenue, Knoxville, Tennessee 37996, United States
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - James C. Gumbart
- School of Physics, Georgia Institute of Technology, 837 State Street NW, Atlanta, Georgia 30332, United States
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20
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Suay-García B, Pérez-Gracia MT. Present and Future of Carbapenem-resistant Enterobacteriaceae (CRE) Infections. Antibiotics (Basel) 2019; 8:E122. [PMID: 31430964 PMCID: PMC6784177 DOI: 10.3390/antibiotics8030122] [Citation(s) in RCA: 167] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/15/2019] [Accepted: 08/16/2019] [Indexed: 12/18/2022] Open
Abstract
Carbapenem-resistant Enterobacteriaceae (CRE) have become a public health threat worldwide. There are three major mechanisms by which Enterobacteriaceae become resistant to carbapenems: enzyme production, efflux pumps and porin mutations. Of these, enzyme production is the main resistance mechanism. There are three main groups of enzymes responsible for most of the carbapenem resistance: KPC (Klebsiella pneumoniae carbapenemase) (Ambler class A), MBLs (Metallo-ß-Lactamases) (Ambler class B) and OXA-48-like (Ambler class D). KPC-producing Enterobacteriaceae are endemic in the United States, Colombia, Argentina, Greece and Italy. On the other hand, the MBL NDM-1 is the main carbapenemase-producing resistance in India, Pakistan and Sri Lanka, while OXA-48-like enzyme-producers are endemic in Turkey, Malta, the Middle-East and North Africa. All three groups of enzymes are plasmid-mediated, which implies an easier horizontal transfer and, thus, faster spread of carbapenem resistance worldwide. As a result, there is an urgent need to develop new therapeutic guidelines to treat CRE infections. Bearing in mind the different mechanisms by which Enterobacteriaceae can become resistant to carbapenems, there are different approaches to treat infections caused by these bacteria, which include the repurposing of already existing antibiotics, dual therapies with these antibiotics, and the development of new ß-lactamase inhibitors and antibiotics.
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Affiliation(s)
- Beatriz Suay-García
- Área de Microbiología, Departamento de Farmacia, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Cardenal Herrera-CEU, C/ Santiago Ramón y Cajal, 46115 Alfara del Patriarca, Valencia, Spain
| | - María Teresa Pérez-Gracia
- Área de Microbiología, Departamento de Farmacia, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Cardenal Herrera-CEU, C/ Santiago Ramón y Cajal, 46115 Alfara del Patriarca, Valencia, Spain.
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21
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Abstract
Iron is essential for the survival of most bacteria but presents a significant challenge given its limited bioavailability. Furthermore, the toxicity of iron combined with the need to maintain physiological iron levels within a narrow concentration range requires sophisticated systems to sense, regulate, and transport iron. Most bacteria have evolved mechanisms to chelate and transport ferric iron (Fe3+) via siderophore receptor systems, and pathogenic bacteria have further lowered this barrier by employing mechanisms to utilize the host's hemoproteins. Once internalized, heme is cleaved by both oxidative and nonoxidative mechanisms to release iron. Heme, itself a lipophilic and toxic molecule, presents a significant challenge for transport into the cell. As such, pathogenic bacteria have evolved sophisticated cell surface signaling and transport systems to obtain heme from the host. In this review, we summarize the structure and function of the heme-sensing and transport systems of pathogenic bacteria and the potential of these systems as antimicrobial targets.
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Affiliation(s)
- Weiliang Huang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201;
| | - Angela Wilks
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201;
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22
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Richard D, Ravigné V, Rieux A, Facon B, Boyer C, Boyer K, Grygiel P, Javegny S, Terville M, Canteros BI, Robène I, Vernière C, Chabirand A, Pruvost O, Lefeuvre P. Adaptation of genetically monomorphic bacteria: evolution of copper resistance through multiple horizontal gene transfers of complex and versatile mobile genetic elements. Mol Ecol 2017; 26:2131-2149. [PMID: 28101896 DOI: 10.1111/mec.14007] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 11/28/2016] [Accepted: 12/08/2016] [Indexed: 12/17/2022]
Abstract
Copper-based antimicrobial compounds are widely used to control plant bacterial pathogens. Pathogens have adapted in response to this selective pressure. Xanthomonas citri pv. citri, a major citrus pathogen causing Asiatic citrus canker, was first reported to carry plasmid-encoded copper resistance in Argentina. This phenotype was conferred by the copLAB gene system. The emergence of resistant strains has since been reported in Réunion and Martinique. Using microsatellite-based genotyping and copLAB PCR, we demonstrated that the genetic structure of the copper-resistant strains from these three regions was made up of two distant clusters and varied for the detection of copLAB amplicons. In order to investigate this pattern more closely, we sequenced six copper-resistant X. citri pv. citri strains from Argentina, Martinique and Réunion, together with reference copper-resistant Xanthomonas and Stenotrophomonas strains using long-read sequencing technology. Genes involved in copper resistance were found to be strain dependent with the novel identification in X. citri pv. citri of copABCD and a cus heavy metal efflux resistance-nodulation-division system. The genes providing the adaptive trait were part of a mobile genetic element similar to Tn3-like transposons and included in a conjugative plasmid. This indicates the system's great versatility. The mining of all available bacterial genomes suggested that, within the bacterial community, the spread of copper resistance associated with mobile elements and their plasmid environments was primarily restricted to the Xanthomonadaceae family.
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Affiliation(s)
- D Richard
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France.,Plant Health Laboratory, ANSES, F-97410, St Pierre, Réunion, France.,Université de la Réunion, UMR PVBMT, F-97490, St Denis, Réunion, France
| | - V Ravigné
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - A Rieux
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - B Facon
- INRA, UMR PVBMT, F-97410, St Pierre, Réunion, France.,INRA, UMR CBGP, F-34090, Montpellier, France
| | - C Boyer
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - K Boyer
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - P Grygiel
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - S Javegny
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - M Terville
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - B I Canteros
- INTA, Estación Experimental Agropecuaria Bella Vista, Bella Vista, Argentina
| | - I Robène
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - C Vernière
- CIRAD, UMR BGPI, F-34398, Montpellier, France
| | - A Chabirand
- Plant Health Laboratory, ANSES, F-97410, St Pierre, Réunion, France
| | - O Pruvost
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
| | - P Lefeuvre
- UMR PVBMT, CIRAD, F-97410, St Pierre, Réunion, France
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23
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Tipton KA, Farokhyfar M, Rather PN. Multiple roles for a novel RND-type efflux system in Acinetobacter baumannii AB5075. Microbiologyopen 2016; 6. [PMID: 27762102 PMCID: PMC5387308 DOI: 10.1002/mbo3.418] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/09/2016] [Accepted: 09/20/2016] [Indexed: 01/26/2023] Open
Abstract
Colony opacity phase variation in Acinetobacter baumannii strain AB5075 is regulated by a reversible high‐frequency switch. Transposon mutagenesis was used to generate mutations that decreased the opaque to translucent switch and a gene encoding a predicted periplasmic membrane fusion component of a resistance–nodulation–cell division (RND)‐type efflux system was isolated. This gene was designated arpA and immediately downstream was a gene designated arpB that encodes a predicted membrane transporter of RND‐type systems. A nonpolar, in‐frame deletion in arpA resulted in a 70‐fold decrease in the opaque to translucent switch. An arpB::Tc mutant exhibited a 769‐fold decrease in the opaque to translucent switch. However, the translucent to opaque switch was largely unchanged in both the arpA and arpB mutants. The arpA and arpB mutants also exhibited increased surface motility in the opaque form and the arpB mutant exhibited increased susceptibility to aminoglycosides. The arpA and arpB mutants were both attenuated in a Galleria mellonella model of virulence. A divergently transcribed TetR‐type regulator ArpR was capable of repressing the arpAB operon when this TetR regulator was overexpressed. The arpR gene was also involved in regulating the opaque to translucent switch as an in‐frame arpR mutation decreased this switch by 1,916‐fold.
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Affiliation(s)
- Kyle A Tipton
- Department of Microbiology and Immunology, Emory University School of Medicine Atlanta, Atlanta, GA, USA
| | | | - Philip N Rather
- Department of Microbiology and Immunology, Emory University School of Medicine Atlanta, Atlanta, GA, USA.,Research Service, Atlanta VA Medical Center, Decatur, GA, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
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24
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Van Acker H, Coenye T. The Role of Efflux and Physiological Adaptation in Biofilm Tolerance and Resistance. J Biol Chem 2016; 291:12565-12572. [PMID: 27129224 DOI: 10.1074/jbc.r115.707257] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Microbial biofilms demonstrate a decreased susceptibility to antimicrobial agents. Various mechanisms have been proposed to be involved in this recalcitrance. We focus on two of these factors. Firstly, the ability of sessile cells to actively mediate efflux of antimicrobial compounds has a profound impact on resistance and tolerance, and several studies point to the existence of biofilm-specific efflux systems. Secondly, biofilm-specific stress responses have a marked influence on cellular physiology, and contribute to the occurrence of persister cells. We provide an overview of the data that demonstrate that both processes are important for survival following exposure to antimicrobial agents.
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Affiliation(s)
- Heleen Van Acker
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, B-9000 Gent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, B-9000 Gent, Belgium.
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25
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Ansell BRE, McConville MJ, Baker L, Korhonen PK, Young ND, Hall RS, Rojas CAA, Svärd SG, Gasser RB, Jex AR. Time-Dependent Transcriptional Changes in Axenic Giardia duodenalis Trophozoites. PLoS Negl Trop Dis 2015; 9:e0004261. [PMID: 26636323 PMCID: PMC4670223 DOI: 10.1371/journal.pntd.0004261] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/03/2015] [Indexed: 12/27/2022] Open
Abstract
Giardia duodenalis is the most common gastrointestinal protozoan parasite of humans and a significant contributor to the global burden of both diarrheal disease and post-infectious chronic disorders. Although G. duodenalis can be cultured axenically, significant gaps exist in our understanding of the molecular biology and metabolism of this pathogen. The present study employed RNA sequencing to characterize the mRNA transcriptome of G. duodenalis trophozoites in axenic culture, at log (48 h of growth), stationary (60 h), and declining (96 h) growth phases. Using ~400-times coverage of the transcriptome, we identified 754 differentially transcribed genes (DTGs), mainly representing two large DTG groups: 438 that were down-regulated in the declining phase relative to log and stationary phases, and 281 that were up-regulated. Differential transcription of prominent antioxidant and glycolytic enzymes implicated oxygen tension as a key factor influencing the transcriptional program of axenic trophozoites. Systematic bioinformatic characterization of numerous DTGs encoding hypothetical proteins of unknown function was achieved using structural homology searching. This powerful approach greatly informed the differential transcription analysis and revealed putative novel antioxidant-coding genes, and the presence of a near-complete two-component-like signaling system that may link cytosolic redox or metabolite sensing to the observed transcriptional changes. Motif searching applied to promoter regions of the two large DTG groups identified different putative transcription factor-binding motifs that may underpin global transcriptional regulation. This study provides new insights into the drivers and potential mediators of transcriptional variation in axenic G. duodenalis and provides context for static transcriptional studies.
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Affiliation(s)
- Brendan R. E. Ansell
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Malcolm J. McConville
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Louise Baker
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Pasi K. Korhonen
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Neil D. Young
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Ross S. Hall
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Cristian A. A. Rojas
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Staffan G. Svärd
- Department of Cell & Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Robin B. Gasser
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Aaron R. Jex
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
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26
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Delmar JA, Su CC, Yu EW. Heavy metal transport by the CusCFBA efflux system. Protein Sci 2015; 24:1720-36. [PMID: 26258953 DOI: 10.1002/pro.2764] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 08/03/2015] [Indexed: 01/11/2023]
Abstract
It is widely accepted that the increased use of antibiotics has resulted in bacteria with developed resistance to such treatments. These organisms are capable of forming multi-protein structures that bridge both the inner and outer membrane to expel diverse toxic compounds directly from the cell. Proteins of the resistance nodulation cell division (RND) superfamily typically assemble as tripartite efflux pumps, composed of an inner membrane transporter, a periplasmic membrane fusion protein, and an outer membrane factor channel protein. These machines are the most powerful antimicrobial efflux machinery available to bacteria. In Escherichia coli, the CusCFBA complex is the only known RND transporter with a specificity for heavy metals, detoxifying both Cu(+) and Ag(+) ions. In this review, we discuss the known structural information for the CusCFBA proteins, with an emphasis on their assembly, interaction, and the relationship between structure and function.
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Affiliation(s)
- Jared A Delmar
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011
| | - Chih-Chia Su
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011
| | - Edward W Yu
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011
- Department of Chemistry, Iowa State University, Ames, Iowa, 50011
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27
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Iyer R, Erwin AL. Direct measurement of efflux in Pseudomonas aeruginosa using an environment-sensitive fluorescent dye. Res Microbiol 2015; 166:516-24. [PMID: 26117599 DOI: 10.1016/j.resmic.2015.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 06/17/2015] [Accepted: 06/18/2015] [Indexed: 11/16/2022]
Abstract
Resistance-Nodulation-Division (RND) family pumps AcrB and MexB are the major efflux routes in Escherichia coli and Pseudomonas aeruginosa respectively. Fluorescent environment-sensitive dyes provide a means to study efflux pump function in live bacterial cells in real-time. Recently, we demonstrated the utility of this approach using the dye Nile Red to quantify AcrB-mediated efflux and measured the ability of antibiotics and other efflux pump substrates to compete with efflux of Nile Red, independent of antibacterial activity. Here, we extend this method to P. aeruginosa and describe a novel application that permits the comparison and rank-ordering of bacterial strains by their inherent efflux potential. We show that glucose and l-malate re-energize Nile Red efflux in P. aeruginosa, and we highlight differences in the glucose dependence and kinetics of efflux between P. aeruginosa and E. coli. We quantify the differences in efflux among a set of P. aeruginosa laboratory strains, which include PAO1, the hyper-sensitive strain ATCC 35151 and its parent, ATCC 12055. Efflux of Nile Red in P. aeruginosa is mediated by MexAB-OprM and is slower than in E. coli. In conclusion, we describe an efflux measurement tool for use in antibacterial drug discovery and basic research on P. aeruginosa efflux pumps.
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Affiliation(s)
- Ramkumar Iyer
- Infectious Diseases Department, Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, MA, USA.
| | - Alice L Erwin
- Infectious Diseases Department, Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, MA, USA
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28
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Abstract
Infections caused by bacteria are a leading cause of death worldwide. Although antibiotics remain a key clinical therapy, their effectiveness has been severely compromised by the development of drug resistance in bacterial pathogens. Multidrug efflux transporters--a common and powerful resistance mechanism--are capable of extruding a number of structurally unrelated antimicrobials from the bacterial cell, including antibiotics and toxic heavy metal ions, facilitating their survival in noxious environments. Transporters of the resistance-nodulation-cell division (RND) superfamily typically assemble as tripartite efflux complexes spanning the inner and outer membranes of the cell envelope. In Escherichia coli, the CusCFBA complex, which mediates resistance to copper(I) and silver(I) ions, is the only known RND transporter specific to heavy metals. Here, we describe the current knowledge of individual pump components of the Cus system, a paradigm for efflux machinery, and speculate on how RND pumps assemble to fight diverse antimicrobials.
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29
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Inhibitors of TonB function identified by a high-throughput screen for inhibitors of iron acquisition in uropathogenic Escherichia coli CFT073. mBio 2014; 5:e01089-13. [PMID: 24570372 PMCID: PMC3940036 DOI: 10.1128/mbio.01089-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The urinary tract is one of the most common sites of infection in humans, and uropathogenic Escherichia coli (UPEC) is the main causative agent of urinary tract infections. Bacteria colonizing the urinary tract face extremely low iron availability. To counteract this, UPEC expresses a wide variety of iron acquisition systems. To exploit iron acquisition in UPEC as a global target for small-molecule inhibition, we developed and carried out a whole-cell growth-based high throughput screen of 149,243 compounds. Our primary assay was carried out under iron-limiting conditions. Hits in the primary screen were assayed using two counterscreens that ruled out iron chelators and compounds that inhibit growth by means other than inhibition of iron acquisition. We determined dose-response curves under two different iron conditions and purchased fresh compounds for selected hits. After retesting dose-response relationships, we identified 16 compounds that arrest growth of UPEC only under iron-limiting conditions. All compounds are bacteriostatic and do not inhibit proton motive force. A loss-of-target strategy was employed to identify the cellular target of these inhibitors. Two compounds lost inhibitory activity against a strain lacking TonB and were shown to inhibit irreversible adsorption of a TonB-dependent bacteriophage. Our results validate iron acquisition as a target for antibacterial strategies against UPEC and identify TonB as one of the cellular targets. Half of women will suffer at least one episode of urinary tract infection (UTI) during their lifetime. The current treatment for UTI involves antibiotic therapy. Resistance to currently used antibiotics has steadily increased over the last decade, generating a pressing need for the development of new therapeutic agents. Since iron is essential for colonization and scarce in the urinary tract, targeting iron acquisition would seem to be an attractive strategy. However, the multiplicity and redundancy of iron acquisition systems in uropathogenic Escherichia coli (UPEC) make it difficult to pinpoint a specific cellular target. Here, we identified 16 iron acquisition inhibitors through a whole-cell high-throughput screen, validating iron acquisition as a target for antibacterial strategies against UPEC. We also identified the cellular target of two of the inhibitors as the TonB system.
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30
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Valade E, Davin-Regli A, Bolla JM, Pagès JM. Bacterial Membrane, a Key for Controlling Drug Influx and Efflux. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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31
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Abstract
Hedgehog (Hh) proteins regulate the development of a wide range of metazoan embryonic and adult structures, and disruption of Hh signaling pathways results in various human diseases. Here, we provide a comprehensive review of the signaling pathways regulated by Hh, consolidating data from a diverse array of organisms in a variety of scientific disciplines. Similar to the elucidation of many other signaling pathways, our knowledge of Hh signaling developed in a sequential manner centered on its earliest discoveries. Thus, our knowledge of Hh signaling has for the most part focused on elucidating the mechanism by which Hh regulates the Gli family of transcription factors, the so-called "canonical" Hh signaling pathway. However, in the past few years, numerous studies have shown that Hh proteins can also signal through Gli-independent mechanisms collectively referred to as "noncanonical" signaling pathways. Noncanonical Hh signaling is itself subdivided into two distinct signaling modules: (i) those not requiring Smoothened (Smo) and (ii) those downstream of Smo that do not require Gli transcription factors. Thus, Hh signaling is now proposed to occur through a variety of distinct context-dependent signaling modules that have the ability to crosstalk with one another to form an interacting, dynamic Hh signaling network.
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Affiliation(s)
- David J Robbins
- Molecular Oncology Program, Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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32
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Why thioridazine in combination with antibiotics cures extensively drug-resistant Mycobacterium tuberculosis infections. Int J Antimicrob Agents 2012; 39:376-80. [PMID: 22445204 DOI: 10.1016/j.ijantimicag.2012.01.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 01/18/2012] [Indexed: 11/22/2022]
Abstract
Thioridazine (TDZ) in combination with antibiotics to which extensively drug-resistant Mycobacterium tuberculosis (XDR-TB) is initially resistant yields a cure. This is due to the fact that TDZ enhances the killing of intracellular M. tuberculosis by non-killing macrophages, inhibits the genetic expression of efflux pumps of M. tuberculosis that extrude antibiotics prior to reaching their intended targets, and inhibits the activity of existing efflux pumps that contribute to the multidrug-resistant phenotype of M. tuberculosis. The combination of these effects of TDZ probably contributes to the successful recent cures of XDR-TB cases when the phenothiazine TDZ is used in combination with antibiotics to which the patient with XDR-TB was initially unresponsive.
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33
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Smith AD, Wilks A. Extracellular heme uptake and the challenges of bacterial cell membranes. CURRENT TOPICS IN MEMBRANES 2012; 69:359-92. [PMID: 23046657 PMCID: PMC3731948 DOI: 10.1016/b978-0-12-394390-3.00013-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In bacteria, the fine balance of maintaining adequate iron levels while preventing the deleterious effects of excess iron has led to the evolution of sophisticated cellular mechanisms to obtain, store, and regulate iron. Iron uptake provides a significant challenge given its limited bioavailability and need to be transported across the bacterial cell wall and membranes. Pathogenic bacteria have circumvented the iron-availability issue by utilizing the hosts' heme-containing proteins as a source of iron. Once internalized, iron is liberated from the porphyrin enzymatically for cellular processes within the bacterial cell. Heme, a lipophilic and toxic molecule, poses a significant challenge in terms of transport given its chemical reactivity. As such, pathogenic bacteria have evolved sophisticated membrane transporters to coordinate, sequester, and transport heme. Recent advances in the biochemical and structural characterization of the membrane-bound heme transport proteins are discussed in the context of ligand coordination, protein-protein interaction, and heme transfer.
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Affiliation(s)
- Aaron D. Smith
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, USA
| | - Angela Wilks
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, USA
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