1
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Cao D, Subhadra B, Lee YJ, Thoresen M, Cornejo S, Olivier A, Woolums A, Inzana TJ. Contribution of Hfq to gene regulation and virulence in Histophilus somni. Infect Immun 2024; 92:e0003824. [PMID: 38391206 PMCID: PMC10929436 DOI: 10.1128/iai.00038-24] [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: 01/26/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Histophilus somni is one of the predominant bacterial pathogens responsible for bovine respiratory and systemic diseases in cattle. Despite the identification of numerous H. somni virulence factors, little is known about the regulation of such factors. The post-transcriptional regulatory protein Hfq may play a crucial role in regulation of components that affect bacterial virulence. The contribution of Hfq to H. somni phenotype and virulence was investigated following creation of an hfq deletion mutant of H. somni strain 2336 (designated H. somni 2336Δhfq). A comparative analysis of the mutant to the wild-type strain was carried out by examining protein and carbohydrate phenotype, RNA sequence, intracellular survival in bovine monocytes, serum susceptibility, and virulence studies in mouse and calf models. H. somni 2336Δhfq exhibited a truncated lipooligosaccharide (LOS) structure, with loss of sialylation. The mutant demonstrated increased susceptibility to intracellular and serum-mediated killing compared to the wild-type strain. Transcriptomic analysis displayed significant differential expression of 832 upregulated genes and 809 downregulated genes in H. somni 2336Δhfq compared to H. somni strain 2336, including significant downregulation of lsgB and licA, which contribute to LOS oligosaccharide synthesis and sialylation. A substantial number of differentially expressed genes were associated with polysaccharide synthesis and other proteins that could influence virulence. The H. somni 2336Δhfq mutant strain was attenuated in a mouse septicemia model and somewhat attenuated in a calf intrabronchial challenge model. H. somni was recovered less frequently from nasopharyngeal swabs, endotracheal aspirates, and lung tissues of calves challenged with H. somni 2336Δhfq compared to the wild-type strain, and the percentage of abnormal lung tissue in calves challenged with H. somni 2336Δhfq was lower than in calves challenged with the wild-type strain. In conclusion, our results support that Hfq accounts for the regulation of H. somni virulence factors.
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Affiliation(s)
- Dianjun Cao
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
| | - Bindu Subhadra
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
| | - Yue-Jia Lee
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
| | - Merrilee Thoresen
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Santiago Cornejo
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Alicia Olivier
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Amelia Woolums
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Thomas J. Inzana
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
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2
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Ganio K, Nasreen M, Yang Z, Maunders EA, Luo Z, Hossain SI, Ngu DHY, Ellis D, Gu J, Neville SL, Wilksch J, Gunn AP, Whittall JJ, Kobe B, Deplazes E, Kappler U, McDevitt CA. Hfe Permease and Haemophilus influenzae Manganese Homeostasis. ACS Infect Dis 2024; 10:436-452. [PMID: 38240689 PMCID: PMC10863617 DOI: 10.1021/acsinfecdis.3c00407] [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: 08/13/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 02/10/2024]
Abstract
Haemophilus influenzae is a commensal of the human upper respiratory tract that can infect diverse host niches due, at least in part, to its ability to withstand both endogenous and host-mediated oxidative stresses. Here, we show that hfeA, a gene previously linked to iron import, is essential for H. influenzae manganese recruitment via the HfeBCD transporter. Structural analyses show that metal binding in HfeA uses a unique mechanism that involves substantial rotation of the C-terminal lobe of the protein. Disruption of hfeA reduced H. influenzae manganese acquisition and was associated with decreased growth under aerobic conditions, impaired manganese-superoxide dismutase activity, reduced survival in macrophages, and changes in biofilm production in the presence of superoxide. Collectively, this work shows that HfeA contributes to H. influenzae manganese acquisition and virulence attributes. High conservation of the hfeABCD permease in Haemophilus species suggests that it may serve similar roles in other pathogenic Pasteurellaceae.
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Affiliation(s)
- Katherine Ganio
- Department
of Microbiology and Immunology, the Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Marufa Nasreen
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
| | - Zihao Yang
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
| | - Eve A. Maunders
- Department
of Microbiology and Immunology, the Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Zhenyao Luo
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
- Institute
for Molecular Bioscience, The University
of Queensland, St Lucia, Queensland 4072, Australia
| | - Sheikh Imamul Hossain
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- School
of Life Sciences, University of Technology
Sydney, Ultimo, New South Wales 2007, Australia
| | - Dalton H. Y. Ngu
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
- Institute
for Molecular Bioscience, The University
of Queensland, St Lucia, Queensland 4072, Australia
| | - Daniel Ellis
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
| | - Jin Gu
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
| | - Stephanie L. Neville
- Department
of Microbiology and Immunology, the Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Jonathan Wilksch
- Department
of Microbiology and Immunology, the Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Adam P. Gunn
- Department
of Microbiology and Immunology, the Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Jonathan J. Whittall
- School of
Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Boštjan Kobe
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
- Institute
for Molecular Bioscience, The University
of Queensland, St Lucia, Queensland 4072, Australia
| | - Evelyne Deplazes
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- School
of Life Sciences, University of Technology
Sydney, Ultimo, New South Wales 2007, Australia
| | - Ulrike Kappler
- School
of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- Australian
Infectious Diseases Research Centre, The
University of Queensland, St Lucia, Queensland 4072, Australia
| | - Christopher A. McDevitt
- Department
of Microbiology and Immunology, the Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3000, Australia
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3
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Zhang YQ, Song XY, Liu F. XanFur, a novel Fur protein induced by H 2O 2, positively regulated by the global transcriptional regulator Clp and required for the full virulence of Xanthomonas oryzae pv. oryzae in rice. Microbiol Spectr 2023; 11:e0118723. [PMID: 37831462 PMCID: PMC10714925 DOI: 10.1128/spectrum.01187-23] [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: 03/22/2023] [Accepted: 08/07/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Although Xanthomonas oryzae pv. oryzae (Xoo) has been found to be a bacterial pathogen causing bacterial leaf blight in rice for many years, the molecular mechanisms of the rice-Xoo interaction has not been fully understood. In this study, we found that XanFur of Xoo is a novel ferric uptake regulator (Fur) protein conserved among major pathogenic Xanthomonas species. XanFur is required for the virulence of Xoo in rice, and likely involved in regulating the virulence determinants of Xoo. The expression of xanfur is induced by H2O2, and positively regulated by the global transcriptional regulator Clp. Our results reveal the function and regulation of the novel virulence-related Fur protein XanFur in Xoo, providing new insights into the interaction mechanisms of rice-Xoo.
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Affiliation(s)
- Yu-Qiang Zhang
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong, China
| | - Xiao-Yan Song
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
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4
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Trouillon J, Attrée I, Elsen S. The regulation of bacterial two-partner secretion systems. Mol Microbiol 2023; 120:159-177. [PMID: 37340956 DOI: 10.1111/mmi.15112] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 06/01/2023] [Accepted: 06/07/2023] [Indexed: 06/22/2023]
Abstract
Two-partner secretion (TPS) systems, also known as Type Vb secretion systems, allow the translocation of effector proteins across the outer membrane of Gram-negative bacteria. By secreting different classes of effectors, including cytolysins and adhesins, TPS systems play important roles in bacterial pathogenesis and host interactions. Here, we review the current knowledge on TPS systems regulation and highlight specific and common regulatory mechanisms across TPS functional classes. We discuss in detail the specific regulatory networks identified in various bacterial species and emphasize the importance of understanding the context-dependent regulation of TPS systems. Several regulatory cues reflecting host environment during infection, such as temperature and iron availability, are common determinants of expression for TPS systems, even across relatively distant species. These common regulatory pathways often affect TPS systems across subfamilies with different effector functions, representing conserved global infection-related regulatory mechanisms.
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Affiliation(s)
- Julian Trouillon
- Université Grenoble Alpes, CNRS, CEA, IBS UMR 5075, Team Bacterial Pathogenesis and Cellular Responses, Grenoble, France
| | - Ina Attrée
- Université Grenoble Alpes, CNRS, CEA, IBS UMR 5075, Team Bacterial Pathogenesis and Cellular Responses, Grenoble, France
| | - Sylvie Elsen
- Université Grenoble Alpes, CNRS, CEA, IBS UMR 5075, Team Bacterial Pathogenesis and Cellular Responses, Grenoble, France
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5
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Huang M, Liu M, Liu J, Wang M, Jia R, Zhu D, Chen S, Zhao X, Yang Q, Wu Y, Zhang S, Gao Q, Huang J, Ou X, Mao S, Tian B, Sun D, Cheng A. Evaluation of the immunoprotection efficacy of Riemerella anatipestifer fur-deficient mutant as an attenuated vaccine. Poult Sci 2022; 102:102450. [PMID: 36621099 PMCID: PMC9841290 DOI: 10.1016/j.psj.2022.102450] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/10/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Riemerella anatipestifer (R. anatipestifer, RA) is an infectious pathogen that causes septicemia and polyserositis in ducks. Our previous studies showed that RA CH-1 ∆fur was significantly attenuated in ducklings, which highlights the potential of this strain as a live attenuated vaccine. In this study, it was shown that infection with 109 CFU of the fur mutant did not cause any clinical symptoms or significant histological lesions in 3-day-old ducklings and that the bacteria were readily cleared by the host within 3 d. Compared with the nonvaccinated group, the group inoculated with the mutant strain RA CH-1 ∆fur exhibited protection of ducklings against a high-dose (2.28 × 1010 CFU) challenge with the wild-type strain RA CH-1. Moreover, the average body weights and body weight gains of the Δfur-inoculated group were not significantly affected by the challenge. Further analysis revealed that RA CH-1 ∆fur elicited higher IgY titers and that the serum antibody levels persisted for at least 49 d after immunization. Overall, our study showed that RA CH-1 ∆fur is a safe and effective vaccine candidate that is expected to play an important role in RA CH-1 infection prevention in the duck industry.
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Affiliation(s)
- Mi Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Jiajun Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Dekang Zhu
- Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Qun Gao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Juan Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Xumin Ou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Bin Tian
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China.
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6
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Janoušková M, Straw ML, Su YC, Riesbeck K. Gene Expression Regulation in Airway Pathogens: Importance for Otitis Media. Front Cell Infect Microbiol 2022; 12:826018. [PMID: 35252035 PMCID: PMC8895709 DOI: 10.3389/fcimb.2022.826018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Otitis media (OM) is an inflammatory disorder in the middle ear. It is mainly caused by viruses or bacteria associated with the airways. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are the three main pathogens in infection-related OM, especially in younger children. In this review, we will focus upon the multifaceted gene regulation mechanisms that are well-orchestrated in S. pneumoniae, H. influenzae, and M. catarrhalis during the course of infection in the middle ear either in experimental OM or in clinical settings. The sophisticated findings from the past 10 years on how the othopathogens govern their virulence phenotypes for survival and host adaptation via phase variation- and quorum sensing-dependent gene regulation, will be systematically discussed. Comprehensive understanding of gene expression regulation mechanisms employed by pathogens during the onset of OM may provide new insights for the design of a new generation of antimicrobial agents in the fight against bacterial pathogens while combating the serious emergence of antimicrobial resistance.
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7
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Atto B, Gell D, Tristram S. Exploiting the struggle for haem: a novel therapeutic approach against Haemophilus influenzae. MICROBIOLOGY AUSTRALIA 2021. [DOI: 10.1071/ma21032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Over the past decade, nontypeable Haemophilus influenzae (NTHi) has gained recognition as a major opportunistic pathogen of the respiratory tract that imposes a substantial global burden of disease, owing to a high rate of morbidity and ensuing complications. Further amplifying the global impact of NTHi infections is the increasing spectrum and prevalence of antibiotic resistance, leading to higher rates of treatment failure with first- and second-line antibiotics regimes. The threat of antibiotic resistance was recognised by the World Health Organization in 2017, listing NTHi as a priority pathogen for which new therapies are urgently needed. Despite significant efforts, there are currently no effective vaccine strategies available that can slow the growing burden of NTHi disease. Consequently, alternative preventative or therapeutic approaches that do not rely on antibiotic susceptibility or stable vaccine targets are becoming more attractive. The nutritional dependency for haem at all stages of NTHi pathogenesis exposes a vulnerability that may be exploited for the development of such therapies. This article will discuss the therapeutic potential of strategies that limit NTHi access to this vital nutrient, with particular focus on a novel bacteriotherapeutic approach under development.
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8
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Staunton PM, Miranda-CasoLuengo AA, Loftus BJ, Gormley IC. BINDER: computationally inferring a gene regulatory network for Mycobacterium abscessus. BMC Bioinformatics 2019; 20:466. [PMID: 31500560 PMCID: PMC6734328 DOI: 10.1186/s12859-019-3042-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/21/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Although many of the genic features in Mycobacterium abscessus have been fully validated, a comprehensive understanding of the regulatory elements remains lacking. Moreover, there is little understanding of how the organism regulates its transcriptomic profile, enabling cells to survive in hostile environments. Here, to computationally infer the gene regulatory network for Mycobacterium abscessus we propose a novel statistical computational modelling approach: BayesIan gene regulatory Networks inferreD via gene coExpression and compaRative genomics (BINDER). In tandem with derived experimental coexpression data, the property of genomic conservation is exploited to probabilistically infer a gene regulatory network in Mycobacterium abscessus.Inference on regulatory interactions is conducted by combining 'primary' and 'auxiliary' data strata. The data forming the primary and auxiliary strata are derived from RNA-seq experiments and sequence information in the primary organism Mycobacterium abscessus as well as ChIP-seq data extracted from a related proxy organism Mycobacterium tuberculosis. The primary and auxiliary data are combined in a hierarchical Bayesian framework, informing the apposite bivariate likelihood function and prior distributions respectively. The inferred relationships provide insight to regulon groupings in Mycobacterium abscessus. RESULTS We implement BINDER on data relating to a collection of 167,280 regulator-target pairs resulting in the identification of 54 regulator-target pairs, across 5 transcription factors, for which there is strong probability of regulatory interaction. CONCLUSIONS The inferred regulatory interactions provide insight to, and a valuable resource for further studies of, transcriptional control in Mycobacterium abscessus, and in the family of Mycobacteriaceae more generally. Further, the developed BINDER framework has broad applicability, useable in settings where computational inference of a gene regulatory network requires integration of data sources derived from both the primary organism of interest and from related proxy organisms.
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Affiliation(s)
- Patrick M. Staunton
- School of Medicine, Conway Institute, University College Dublin, Dublin, Ireland
| | | | - Brendan J. Loftus
- School of Medicine, Conway Institute, University College Dublin, Dublin, Ireland
| | - Isobel Claire Gormley
- School of Mathematics and Statistics, Insight Centre for Data Analytics, University College Dublin, Dublin, Ireland
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9
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Khajanchi BK, Xu J, Grim CJ, Ottesen AR, Ramachandran P, Foley SL. Global transcriptomic analyses of Salmonella enterica in Iron-depleted and Iron-rich growth conditions. BMC Genomics 2019; 20:490. [PMID: 31195964 PMCID: PMC6567447 DOI: 10.1186/s12864-019-5768-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 05/03/2019] [Indexed: 02/06/2023] Open
Abstract
Background Salmonella enterica possess several iron acquisition systems, encoded on the chromosome and plasmids. Recently, we demonstrated that incompatibility group (Inc) FIB plasmid-encoded iron acquisition systems (Sit and aerobactin) likely play an important role in persistence of Salmonella in human intestinal epithelial cells (Caco-2). In this study, we sought to determine global transcriptome analyses of S. enterica in iron-rich (IR) and iron-depleted (ID) growth conditions. Results The number of differentially-expressed genes were substantially higher for recipient (SE819) (n = 966) and transconjugant (TC) (n = 945) compared to the wild type (WT) (SE163A) (n = 110) strain in ID as compared to IR growth conditions. Several virulence-associated factors including T3SS, flagellin, cold-shock protein (cspE), and regulatory genes were upregulated in TC in ID compared to IR conditions. Whereas, IS1 and acrR/tetR transposases located on the IncFIB plasmid, ferritin and several regulatory genes were downregulated in TC in ID conditions. Enterobactin transporter (entS), iron ABC transporter (fepCD), colicin transporter, IncFIB-encoded enolase, cyclic di-GMP regulator (cdgR) and other regulatory genes of the WT strain were upregulated in ID compared to IR conditions. Conversely, ferritin, ferrous iron transport protein A (feoA), IncFIB-encoded IS1 and acrR/tetR transposases and ArtA toxin of WT were downregulated in ID conditions. SDS-PAGE coupled with LC-MS/MS analyses revealed that siderophore receptor proteins such as chromosomally-encoded IroN and, IncFIB-encoded IutA were upregulated in WT and TC in ID growth conditions. Both chromosome and IncFIB plasmid-encoded SitA was overexpressed in WT, but not in TC or recipient in ID conditions. Increased expression of flagellin was detected in recipient and TC, but not in WT in ID conditions. Conclusion Iron concentrations in growth media influenced differential gene expressions both at transcriptional and translational levels, including genes encoded on the IncFIB plasmid. Limited iron availability within the host may promote pathogenic Salmonella to differentially express subsets of genes encoded by chromosome and/or plasmids, facilitating establishment of successful infection. Electronic supplementary material The online version of this article (10.1186/s12864-019-5768-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bijay K Khajanchi
- National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA.
| | - Joshua Xu
- National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA
| | - Christopher J Grim
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, Laurel, MD, USA
| | - Andrea R Ottesen
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, College Park, MD, USA
| | - Padmini Ramachandran
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, College Park, MD, USA
| | - Steven L Foley
- National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA.
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10
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Microevolution in response to transient heme-iron restriction enhances intracellular bacterial community development and persistence. PLoS Pathog 2018; 14:e1007355. [PMID: 30332468 PMCID: PMC6205647 DOI: 10.1371/journal.ppat.1007355] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 10/29/2018] [Accepted: 09/24/2018] [Indexed: 11/19/2022] Open
Abstract
Bacterial pathogens must sense, respond and adapt to a myriad of dynamic microenvironmental stressors to survive. Adaptation is key for colonization and long-term ability to endure fluctuations in nutrient availability and inflammatory processes. We hypothesize that strains adapted to survive nutrient deprivation are more adept for colonization and establishment of chronic infection. In this study, we detected microevolution in response to transient nutrient limitation through mutation of icc. The mutation results in decreased 3',5'-cyclic adenosine monophosphate phosphodiesterase activity in nontypeable Haemophilus influenzae (NTHI). In a preclinical model of NTHI-induced otitis media (OM), we observed a significant decrease in the recovery of effusion from ears infected with the icc mutant strain. Clinically, resolution of OM coincides with the clearance of middle ear fluid. In contrast to this clinical paradigm, we observed that the icc mutant strain formed significantly more intracellular bacterial communities (IBCs) than the parental strain early during experimental OM. Although the number of IBCs formed by the parental strain was low at early stages of OM, we observed a significant increase at later stages that coincided with absence of recoverable effusion, suggesting the presence of a mucosal reservoir following resolution of clinical disease. These data provide the first insight into NTHI microevolution during nutritional limitation and provide the first demonstration of IBCs in a preclinical model of chronic OM. Nontypeable Haemophilus influenzae (NTHI) inhabits diverse niches in the host. The ability to adapt to new microenvironments is consistent with the predominance of NTHI as a causative agent of otitis media (OM) in children. We evaluated the microevolution of NTHI associated with adaptation and persistence in response to nutrient limitation. We identified a naturally occurring mutation that enhances NTHI persistence and formation of intracellular bacterial communities (IBCs) in a pre-clinical model of OM. The presence of IBCs during OM provides the first opportunity to evaluate the role of intracellular populations in chronicity and quiescence as a new paradigm for recurrent OM. This model provides a new platform to identify novel therapeutics for this highly prevalent and costly infectious disease.
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11
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Hardison RL, Heimlich DR, Harrison A, Beatty WL, Rains S, Moseley MA, Thompson JW, Justice SS, Mason KM. Transient Nutrient Deprivation Promotes Macropinocytosis-Dependent Intracellular Bacterial Community Development. mSphere 2018; 3:3/5/e00286-18. [PMID: 30209128 PMCID: PMC6135960 DOI: 10.1128/msphere.00286-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Nutrient limitation restricts bacterial growth in privileged sites such as the middle ear. Transient heme-iron restriction of nontypeable Haemophilus influenzae (NTHI), the major causative agent of chronic and recurrent otitis media (OM), promotes new and diverse phenotypes that can influence planktonic, biofilm, and intracellular lifestyles of NTHI. However, the bacterial responses to nutrient restriction that impact intracellular fate and survival of NTHI are unknown. In this work, we provide evidence for the role of transient heme-iron restriction in promoting the formation of intracellular bacterial communities (IBCs) of NTHI both in vitro and in vivo in a preclinical model of OM. We show that transient heme-iron restriction of NTHI results in significantly increased invasion and intracellular populations that escape or evade the endolysosomal pathway for increased intracellular survival. In contrast, NTHI continuously exposed to heme-iron traffics through the endolysosomal pathway for degradation. The use of pharmacological inhibitors revealed that prior heme-iron status does not appear to influence NTHI internalization through endocytic pathways. However, inhibition of macropinocytosis altered the intracellular fate of transiently restricted NTHI for degradation in the endolysosomal pathway. Furthermore, prevention of macropinocytosis significantly reduced the number of IBCs in cultured middle ear epithelial cells, providing evidence for the feasibility of this approach to reduce OM persistence. These results reveal that microenvironmental cues can influence the intracellular fate of NTHI, leading to new mechanisms for survival during disease progression.IMPORTANCE Otitis media is the most common bacterial infection in childhood. Current therapies are limited in the prevention of chronic or recurrent otitis media which leads to increased antibiotic exposure and represents a significant socioeconomic burden. In this study, we delineate the effect of nutritional limitation on the intracellular trafficking pathways used by nontypeable Haemophilus influenzae (NTHI). Moreover, transient limitation of heme-iron led to the development of intracellular bacterial communities that are known to contribute to persistence and recurrence in other diseases. New approaches for therapeutic interventions that reduce the production of intracellular bacterial communities and promote trafficking through the endolysosomal pathway were revealed through the use of pharmacological inhibition of macropinocytosis. This work demonstrates the importance of an intracellular niche for NTHI and provides new approaches for intervention for acute, chronic, and recurring episodes of otitis media.
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Affiliation(s)
- Rachael L Hardison
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
- The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Derek R Heimlich
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Alistair Harrison
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Wandy L Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sarah Rains
- Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Durham, North Carolina, USA
| | - M Arthur Moseley
- Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Durham, North Carolina, USA
| | - J Will Thompson
- Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Durham, North Carolina, USA
| | - Sheryl S Justice
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Kevin M Mason
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
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12
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Novotny LA, Brockman KL, Mokrzan EM, Jurcisek JA, Bakaletz LO. Biofilm biology and vaccine strategies for otitis media due to nontypeable Haemophilus influenzae. J PEDIAT INF DIS-GER 2018; 14:69-77. [PMID: 30853830 DOI: 10.1055/s-0038-1660818] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Otitis media (OM) is one of the most common diseases of childhood, and nontypeable Haemophilus influenzae (NTHI) is the predominant causative agent of chronic and recurrent OM, as well as OM for which treatment has failed. Moreover, NTHI is now as important a causative agent of acute OM as the pneumococcus. NTHI colonizes the human nasopharynx asymptomatically. However, upon perturbation of the innate and physical defenses of the airway by upper respiratory tract viral infection, NTHI can replicate, ascend the Eustachian tube, gain access to the normally sterile middle ear space, and cause disease. Bacterial biofilms within the middle ear, including those formed by NTHI, contribute to the chronic and recurrent nature of this disease. These multicomponent structures are highly resistant to clearance by host defenses and elimination by traditional antimicrobial therapies. Herein, we review several strategies utilized by NTHI in order to persist within the human host and interventions currently under investigation to prevent and/or resolve NTHI-induced diseases of the middle ear and uppermost airway.
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Affiliation(s)
- Laura A Novotny
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - Kenneth L Brockman
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - Elaine M Mokrzan
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - Joseph A Jurcisek
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
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13
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Ahearn CP, Gallo MC, Murphy TF. Insights on persistent airway infection by non-typeable Haemophilus influenzae in chronic obstructive pulmonary disease. Pathog Dis 2017; 75:3753446. [PMID: 28449098 PMCID: PMC5437125 DOI: 10.1093/femspd/ftx042] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/28/2017] [Indexed: 12/21/2022] Open
Abstract
Non-typeable Haemophilus influenzae (NTHi) is the most common bacterial cause of infection of the lower airways in adults with chronic obstructive pulmonary disease (COPD). Infection of the COPD airways causes acute exacerbations, resulting in substantial morbidity and mortality. NTHi has evolved multiple mechanisms to establish infection in the hostile environment of the COPD airways, allowing the pathogen to persist in the airways for months to years. Persistent infection of the COPD airways contributes to chronic airway inflammation that increases symptoms and accelerates the progressive loss of pulmonary function, which is a hallmark of the disease. Persistence mechanisms of NTHi include the expression of multiple redundant adhesins that mediate binding to host cellular and extracellular matrix components. NTHi evades host immune recognition and clearance by invading host epithelial cells, forming biofilms, altering gene expression and displaying surface antigenic variation. NTHi also binds host serum factors that confer serum resistance. Here we discuss the burden of COPD and the role of NTHi infections in the course of the disease. We provide an overview of NTHi mechanisms of persistence that allow the pathogen to establish a niche in the hostile COPD airways.
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Affiliation(s)
- Christian P. Ahearn
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Mary C. Gallo
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Timothy F. Murphy
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Division of Infectious Disease, Department of Medicine, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
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14
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Lin J, Hafrén H, Kerschner J, Jian-Dong L, Brown S, Zheng QY, Preciado D, Nakamura Y, Huang Q, Zhang Y. Panel 3: Genetics and Precision Medicine of Otitis Media. Otolaryngol Head Neck Surg 2017; 156:S41-S50. [PMID: 28372532 PMCID: PMC6211190 DOI: 10.1177/0194599816685559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 12/01/2016] [Indexed: 12/31/2022]
Abstract
Objective The objective is to perform a comprehensive review of the literature up to 2015 on the genetics and precision medicine relevant to otitis media. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels were formed comprising experts in the genetics and precision medicine of otitis media. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a merged draft was created. The entire panel met at the 18th International Symposium on Recent Advances in Otitis Media in June 2015 and discussed the review and refined the content. A final draft was made, circulated, and approved by the panel members. Conclusion Many genes relevant to otitis media have been identified in the last 4 years in advancing our knowledge regarding the predisposition of the middle ear mucosa to commensals and pathogens. Advances include mutant animal models and clinical studies. Many signaling pathways are involved in the predisposition of otitis media. Implications for Practice New knowledge on the genetic background relevant to otitis media forms a basis of novel potential interventions, including potential new ways to treat otitis media.
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Affiliation(s)
- Jizhen Lin
- Department of Otolaryngology–Head and Neck Surgery, University of Minnesota, Minneapolis, Minnesota, USA
| | - Hena Hafrén
- Departments of Otorhinolaryngology–Head and Neck Surgery, Helsinki University Hospital, Helsinki, Finland
| | - Joseph Kerschner
- Department of Otorhinolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Li Jian-Dong
- Center for Inflammation, Immunity and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia, USA
| | - Steve Brown
- Medical Research Council Harwell Institute, Oxfordshire, UK
| | - Qing Y. Zheng
- Department of Otolaryngology–Head and Neck Surgery, Case Western University, Cleveland, Ohio, USA
| | - Diego Preciado
- Shiekh Zayed Institute for Pediatric Surgical Innovation, Pediatric Otolaryngology, Children’s National Health System, Washington, DC, USA
| | | | - Qiuhong Huang
- Department of Otolaryngology, Sun Yat-sen University, Guangzhou, China
| | - Yan Zhang
- Department of Otolaryngology, Second Affiliated Hospital, Xi’an Jiaotong University, Xi’an, China
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15
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Barenkamp SJ, Chonmaitree T, Hakansson AP, Heikkinen T, King S, Nokso-Koivisto J, Novotny LA, Patel JA, Pettigrew M, Swords WE. Panel 4: Report of the Microbiology Panel. Otolaryngol Head Neck Surg 2017; 156:S51-S62. [PMID: 28372529 PMCID: PMC5490388 DOI: 10.1177/0194599816639028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 02/24/2016] [Indexed: 12/12/2022]
Abstract
Objective To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.
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Affiliation(s)
- Stephen J. Barenkamp
- Department of Pediatrics, St Louis University School of Medicine, St Louis, Missouri, USA
| | - Tasnee Chonmaitree
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Terho Heikkinen
- Department of Pediatrics, University of Turku and Turku University Hospital, Turku, Finland
| | - Samantha King
- The Research Institute at Nationwide Children’s Hospital and Ohio State University, Columbus, Ohio, USA
| | - Johanna Nokso-Koivisto
- Department of Otorhinolaryngology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Laura A. Novotny
- The Research Institute at Nationwide Children’s Hospital and Ohio State University, Columbus, Ohio, USA
| | - Janak A. Patel
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Melinda Pettigrew
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, USA
| | - W. Edward Swords
- Department of Microbiology and Immunology, Wake Forest University, Winston-Salem, North Carolina, USA
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16
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Cephalosporin-3'-Diazeniumdiolate NO Donor Prodrug PYRRO-C3D Enhances Azithromycin Susceptibility of Nontypeable Haemophilus influenzae Biofilms. Antimicrob Agents Chemother 2017; 61:AAC.02086-16. [PMID: 27919896 DOI: 10.1128/aac.02086-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/26/2016] [Indexed: 01/12/2023] Open
Abstract
PYRRO-C3D is a cephalosporin-3-diazeniumdiolate nitric oxide (NO) donor prodrug designed to selectively deliver NO to bacterial infection sites. The objective of this study was to assess the activity of PYRRO-C3D against nontypeable Haemophilus influenzae (NTHi) biofilms and examine the role of NO in reducing biofilm-associated antibiotic tolerance. The activity of PYRRO-C3D on in vitro NTHi biofilms was assessed through CFU enumeration and confocal microscopy. NO release measurements were performed using an ISO-NO probe. NTHi biofilms grown on primary ciliated respiratory epithelia at an air-liquid interface were used to investigate the effects of PYRRO-C3D in the presence of host tissue. Label-free liquid chromatography-mass spectrometry (LC/MS) proteomic analyses were performed to identify differentially expressed proteins following NO treatment. PYRRO-C3D specifically released NO in the presence of NTHi, while no evidence of spontaneous NO release was observed when the compound was exposed to primary epithelial cells. NTHi lacking β-lactamase activity failed to trigger NO release. Treatment significantly increased the susceptibility of in vitro NTHi biofilms to azithromycin, causing a log fold reduction (10-fold reduction or 1-log-unit reduction) in viability (P < 0.05) relative to azithromycin alone. The response was more pronounced for biofilms grown on primary respiratory epithelia, where a 2-log-unit reduction was observed (P < 0.01). Label-free proteomics showed that NO increased expression of 16 proteins involved in metabolic and transcriptional/translational functions. NO release from PYRRO-C3D enhances the efficacy of azithromycin against NTHi biofilms, putatively via modulation of NTHi metabolic activity. Adjunctive therapy with NO mediated through PYRRO-C3D represents a promising approach for reducing biofilm-associated antibiotic tolerance.
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17
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Duell BL, Su YC, Riesbeck K. Host-pathogen interactions of nontypeable Haemophilus influenzae: from commensal to pathogen. FEBS Lett 2016; 590:3840-3853. [PMID: 27508518 DOI: 10.1002/1873-3468.12351] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/01/2016] [Accepted: 08/05/2016] [Indexed: 11/09/2022]
Abstract
Nontypeable Haemophilus influenzae (NTHi) is a commensal microbe often isolated from the upper and lower respiratory tract. This bacterial species can cause sinusitis, acute otitis media in preschool children, exacerbations in patients suffering from chronic obstructive pulmonary disease, as well as conjunctivitis and bacteremia. Since the introduction of a vaccine against H. influenzae serotype b in the 1990s, the burden of H. influenzae-related infections has been increasingly dominated by NTHi. Understanding the ability of NTHi to cause infection is currently an expanding area of study. NTHi is able to exert differential binding to the host tissue through the use of a broad range of adhesins. NTHi survival in the host is multifaceted, that is, using virulence factors involved in complement resistance, biofilm, modified immunoglobulin responses, and, finally, formation and utilization of host proteins as a secondary strategy of increasing the adhesive ability.
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Affiliation(s)
- Benjamin Luke Duell
- Clinical Microbiology, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Yu-Ching Su
- Clinical Microbiology, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Kristian Riesbeck
- Clinical Microbiology, Department of Translational Medicine, Lund University, Malmö, Sweden
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18
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Sun D, Crowell SA, Harding CM, De Silva PM, Harrison A, Fernando DM, Mason KM, Santana E, Loewen PC, Kumar A, Liu Y. KatG and KatE confer Acinetobacter resistance to hydrogen peroxide but sensitize bacteria to killing by phagocytic respiratory burst. Life Sci 2016; 148:31-40. [PMID: 26860891 DOI: 10.1016/j.lfs.2016.02.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 01/28/2016] [Accepted: 02/05/2016] [Indexed: 02/05/2023]
Abstract
AIMS Catalase catalyzes the degradation of H2O2. Acinetobacter species have four predicted catalase genes, katA, katE, katG, and katX. The aims of the present study seek to determine which catalase(s) plays a predominant role in determining the resistance to H2O2, and to assess the role of catalase in Acinetobacter virulence. MAIN METHODS Mutants of Acinetobacter baumannii and Acinetobacter nosocomialis with deficiencies in katA, katE, katG, and katX were tested for sensitivity to H2O2, either by halo assays or by liquid culture assays. Respiratory burst of neutrophils, in response to A. nosocomialis, was assessed by chemiluminescence to examine the effects of catalase on the production of reactive oxygen species (ROS) in neutrophils. Bacterial virulence was assessed using a Galleria mellonella larva infection model. KEY FINDINGS The capacities of A. baumannii and A. nosocomialis to degrade H2O2 are largely dependent on katE. The resistance of both A. baumannii and A. nosocomialis to H2O2 is primarily determined by the katG gene, although katE also plays a minor role in H2O2 resistance. Bacteria lacking both the katG and katE genes exhibit the highest sensitivity to H2O2. While A. nosocomialis bacteria with katE and/or katG were able to decrease ROS production by neutrophils, these cells also induced a more robust respiratory burst in neutrophils than did cells deficient in both katE and katG. We also found that A. nosocomialis deficient in both katE and katG was more virulent than the wildtype A. nosocomialis strain. SIGNIFICANCE Our findings suggest that inhibition of Acinetobacter catalase may help to overcome the resistance of Acinetobacter species to microbicidal H2O2 and facilitate bacterial disinfection.
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Affiliation(s)
- Daqing Sun
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Surgery, The Second Hospital of Shandong University, Jinan, Shandong, China
| | - Sara A Crowell
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Christian M Harding
- Center of Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - P Malaka De Silva
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Alistair Harrison
- Center of Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Dinesh M Fernando
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Kevin M Mason
- Center of Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Estevan Santana
- Center of Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Peter C Loewen
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Ayush Kumar
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Medical Microbiology, College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Yusen Liu
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.
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19
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A novel mechanism for the biogenesis of outer membrane vesicles in Gram-negative bacteria. Nat Commun 2016; 7:10515. [PMID: 26806181 PMCID: PMC4737802 DOI: 10.1038/ncomms10515] [Citation(s) in RCA: 287] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/15/2015] [Indexed: 12/20/2022] Open
Abstract
Bacterial outer membrane vesicles (OMVs) have important biological roles in pathogenesis and intercellular interactions, but a general mechanism of OMV formation is lacking. Here we show that the VacJ/Yrb ABC (ATP-binding cassette) transport system, a proposed phospholipid transporter, is involved in OMV formation. Deletion or repression of VacJ/Yrb increases OMV production in two distantly related Gram-negative bacteria, Haemophilus influenzae and Vibrio cholerae. Lipidome analyses demonstrate that OMVs from VacJ/Yrb-defective mutants in H. influenzae are enriched in phospholipids and certain fatty acids. Furthermore, we demonstrate that OMV production and regulation of the VacJ/Yrb ABC transport system respond to iron starvation. Our results suggest a new general mechanism of OMV biogenesis based on phospholipid accumulation in the outer leaflet of the outer membrane. This mechanism is highly conserved among Gram-negative bacteria, provides a means for regulation, can account for OMV formation under all growth conditions, and might have important pathophysiological roles in vivo. Bacteria release outer membrane vesicles (OMVs) that play important roles in pathogenesis and intercellular interactions. Here, Roier et al. provide evidence supporting that phospholipid accumulation in the outer leaflet of the outer membrane participates in OMV formation in Gram-negative bacteria.
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20
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Harrison A, Dubois LG, St John-Williams L, Moseley MA, Hardison RL, Heimlich DR, Stoddard A, Kerschner JE, Justice SS, Thompson JW, Mason KM. Comprehensive Proteomic and Metabolomic Signatures of Nontypeable Haemophilus influenzae-Induced Acute Otitis Media Reveal Bacterial Aerobic Respiration in an Immunosuppressed Environment. Mol Cell Proteomics 2015; 15:1117-38. [PMID: 26711468 DOI: 10.1074/mcp.m115.052498] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Indexed: 12/31/2022] Open
Abstract
A thorough understanding of the molecular details of the interactions between bacteria and host are critical to ultimately prevent disease. Recent technological advances allow simultaneous analysis of host and bacterial protein and metabolic profiles from a single small tissue sample to provide insight into pathogenesis. We used the chinchilla model of human otitis media to determine, for the first time, the most expansive delineation of global changes in protein and metabolite profiles during an experimentally induced disease. After 48 h of infection with nontypeable Haemophilus influenzae, middle ear tissue lysates were analyzed by high-resolution quantitative two-dimensional liquid chromatography-tandem mass spectrometry. Dynamic changes in 105 chinchilla proteins and 66 metabolites define the early proteomic and metabolomic signature of otitis media. Our studies indicate that establishment of disease coincides with actin morphogenesis, suppression of inflammatory mediators, and bacterial aerobic respiration. We validated the observed increase in the actin-remodeling complex, Arp2/3, and experimentally showed a role for Arp2/3 in nontypeable Haemophilus influenzae invasion. Direct inhibition of actin branch morphology altered bacterial invasion into host epithelial cells, and is supportive of our efforts to use the information gathered to modify outcomes of disease. The twenty-eight nontypeable Haemophilus influenzae proteins identified participate in carbohydrate and amino acid metabolism, redox homeostasis, and include cell wall-associated metabolic proteins. Quantitative characterization of the molecular signatures of infection will redefine our understanding of host response driven developmental changes during pathogenesis. These data represent the first comprehensive study of host protein and metabolite profiles in vivo in response to infection and show the feasibility of extensive characterization of host protein profiles during disease. Identification of novel protein targets and metabolic biomarkers will advance development of therapeutic and diagnostic options for treatment of disease.
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Affiliation(s)
- Alistair Harrison
- From the ‡The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205
| | - Laura G Dubois
- ‡‡Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Medical Center, Durham, North Carolina 27710
| | - Lisa St John-Williams
- ‡‡Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Medical Center, Durham, North Carolina 27710
| | - M Arthur Moseley
- ‡‡Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Medical Center, Durham, North Carolina 27710
| | - Rachael L Hardison
- From the ‡The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205
| | - Derek R Heimlich
- From the ‡The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205
| | | | - Joseph E Kerschner
- ‖Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin 53226; **Division of Pediatric Otolaryngology, Children's Hospital of Wisconsin, Milwaukee, Wisconsin 53226
| | - Sheryl S Justice
- From the ‡The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205; §The Center for Microbial Interface Biology and Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210
| | - J Will Thompson
- ‡‡Duke Proteomics and Metabolomics Core Facility, Duke Center for Genomic and Computational Biology, Duke University, Medical Center, Durham, North Carolina 27710
| | - Kevin M Mason
- From the ‡The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio 43205; §The Center for Microbial Interface Biology and Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210;
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Jiang D, Tikhomirova A, Kidd SP. Haemophilus influenzae strains possess variations in the global transcriptional profile in response to oxygen levels and this influences sensitivity to environmental stresses. Res Microbiol 2015; 167:13-9. [PMID: 26362945 DOI: 10.1016/j.resmic.2015.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 08/05/2015] [Accepted: 08/27/2015] [Indexed: 01/22/2023]
Abstract
An alcohol dehydrogenase, AdhC, is required for Haemophilus influenzae Rd KW20 growth with high oxygen. AdhC protects against both exogenous and metabolically generated, endogenous reactive aldehydes. However, adhC in the strain 86-028NP is a pseudogene. Unlike the Rd KW20 adhC mutant, 86-028NP does grow with high oxygen. This suggests the differences between Rd KW20 and 86-028NP include broader pathways, such as for the maintenance of redox and metabolism that avoids the toxicity related to oxygen. We hypothesized that these differences affect their resistance to relevant toxic chemicals, including reactive aldehydes. Across a range of oxygen concentrations, despite the growth profiles of Rd KW20 and 86-028NP being similar, there was a significant variation in their sensitivity to reactive aldehydes. 86-028NP is more sensitive to methylglyoxal, formaldehyde and glycolaldehyde under high oxygen than low oxygen as well as compared to Rd KW20. Also, as oxygen levels changed the whole genome gene expression profiles of Rd KW20 and 86-028NP revealed distinctions in their transcriptomes (the iron, FNR and ArcAB regulons). These were indicative of a difference in their intracellular redox properties and we show it is this that underpins their survival against reactive aldehydes.
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Affiliation(s)
- Donald Jiang
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Sciences, The University of Adelaide, North Terrace Campus, Adelaide, South Australia, 5005, Australia
| | - Alexandra Tikhomirova
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Sciences, The University of Adelaide, North Terrace Campus, Adelaide, South Australia, 5005, Australia
| | - Stephen P Kidd
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Sciences, The University of Adelaide, North Terrace Campus, Adelaide, South Australia, 5005, Australia.
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Liu L, Chi H, Sun L. Pseudomonas fluorescens: identification of Fur-regulated proteins and evaluation of their contribution to pathogenesis. DISEASES OF AQUATIC ORGANISMS 2015; 115:67-80. [PMID: 26119301 DOI: 10.3354/dao02874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Pseudomonas fluorescens is a Gram-negative bacterium and a common pathogen to a wide range of farmed fish. In a previous study, we found that the ferric uptake regulator gene (fur) is essential to the infectivity of a pathogenic fish isolate of P. fluorescens (wild-type strain TSS). In the present work, we conducted comparative proteomic analysis to examine the global protein profiles of TSS and the P. fluorescens fur knockout mutant TFM. Twenty-eight differentially produced proteins were identified, which belong to different functional categories. Four of these proteins, viz. TssP (a type VI secretion protein), PspA (a serine protease), OprF (an outer membrane porin), and ClpP (the proteolytic subunit of an ATP-dependent Clp protease), were assessed for virulence participation in a model of turbot Scophthalmus maximus. The results showed that the oprF and clpP knockouts exhibited significantly reduced capacities in (1) resistance against the bactericidal effect of host serum, (2) dissemination into and colonization of host tissues, and (3) inducing host mortality. In contrast, mutation of tssP and pspA had no apparent effect on the pathogenicity of TSS. Purified recombinant OprF, when used as a subunit vaccine, induced production of specific serum antibodies in immunized fish and elicited significant protection against lethal TSS challenge. Antibody blocking of the OprF in TSS significantly impaired the ability of the bacteria to invade host tissues. Taken together, these results indicate for the first time that in pathogenic P. fluorescens, Fur regulates the expression of diverse proteins, some of which are required for optimal infection.
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Affiliation(s)
- Li Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, PR China
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Osgood R, Salamone F, Diaz A, Casey JR, Bajorski P, Pichichero ME. Effect of pH and oxygen on biofilm formation in acute otitis media associated NTHi clinical isolates. Laryngoscope 2015; 125:2204-8. [PMID: 25970856 DOI: 10.1002/lary.25102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2014] [Indexed: 01/09/2023]
Abstract
OBJECTIVES/HYPOTHESIS Biofilms occur in animal models of acute otitis media (AOM) and in children with recurrent AOM (rAOM) and chronic otitis media with effusion (OME). We therefore studied the ability of nontypeable Haemophilus influenzae (NTHi) strains from children to form biofilms in vitro under conditions we presumed occurred in the middle ear during AOM, rAOM, and OME. STUDY DESIGN Evaluate NTHi isolates for biofilm formation across a pH range under aerobic, microaerophilic, and anaerobic conditions. METHODS Using a crystal violet biofilm assay we studied 12 NTHi pediatric clinical isolates to investigate biofilm formation over a pH range of 4.5 to 10 under aerobic, microaerophilic, and anaerobic conditions. RESULTS Our findings included: 1) not all clinical NTHi strains form biofilms (75% did); 2) the pH of middle ear fluid collected from AOM (n = 170; age range, 4-36 months), rAOM (n = 54; age range, 7-36 months), and OME (n = 30; age range, 9-60 months) subjects tested immediately after withdrawal was similar (mean = 8.0;range 7.0-9.0); 3) biofilms formed optimally at pH 8.0, a finding that is consistent with previous studies by other investigators; 4) biofilms did not form under aerobic conditions as likely occurs in AOM, whereas under microaerophilic and anaerobic conditions biofilm formation was observed as likely occurs during rAOM and OME. CONCLUSIONS We concluded that biofilm formation by NTHi does not occur in all strains, occurs best where the pH = 8.0 and in anaerobic conditions as likely occurs in children during rAOM and OME. However, biofilm formation is limited or absent under aerobic conditions as likely occurs during AOM. LEVEL OF EVIDENCE NA.
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Affiliation(s)
- Robert Osgood
- Rochester Institute of Technology, Rochester, New York
| | | | - Alexis Diaz
- Rochester Institute of Technology, Rochester, New York
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Interplay between iron homeostasis and virulence: Fur and RyhB as major regulators of bacterial pathogenicity. Vet Microbiol 2015; 179:2-14. [PMID: 25888312 DOI: 10.1016/j.vetmic.2015.03.024] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/23/2015] [Accepted: 03/25/2015] [Indexed: 11/21/2022]
Abstract
In bacteria-host interactions, competition for iron is critical for the outcome of the infection. As a result of its redox properties, this metal is essential for the growth and proliferation of most living organisms, including pathogenic bacteria. This metal is also potentially toxic, making the precise maintenance of iron homeostasis necessary for survival. Iron acquisition and storage control is mediated in most bacteria by the global ferric uptake regulator (Fur) and iron-responsive small regulatory non-coding RNAs (RyhB in the model organism Escherichia coli). While the role of these regulators in iron homeostasis is well documented in both pathogenic and non-pathogenic bacteria, many recent studies also demonstrate that these regulators are involved in the virulence of pathogenic bacteria. By sensing iron availability in the environment, Fur and RyhB are able to regulate, either directly or indirectly via other transcriptional regulators or modulation of intracellular iron concentration, many virulence determinants of pathogenic bacteria. Iron is thus both a nutritional and regulatory element, allowing bacteria to adapt to various host environments by adjusting expression of virulence factors. In this review, we present evidences that Fur and RyhB are the major regulators of this adaptation, as they are involved in diverse functions ranging from iron homeostasis to regulation of virulence by mediating key pathogen responses such as invasion of eukaryotic cells, toxin production, motility, quorum sensing, stress resistance or biofilm formation. Therefore, Fur and RyhB play a major role in regulating an adaptative response during bacterial infections, making them important targets in the fight against pathogenic bacteria.
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Haemophilus influenzae: recent advances in the understanding of molecular pathogenesis and polymicrobial infections. Curr Opin Infect Dis 2015; 27:268-74. [PMID: 24699388 DOI: 10.1097/qco.0000000000000056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Non-typeable Haemophilus influenzae (NTHi) is a human-specific mucosal pathogen and one of the most common causes of bacterial infections in children and patients with chronic obstructive pulmonary disease. It is also frequently found in polymicrobial superinfections. Great strides have recently been made in the understanding of the molecular mechanisms underlying NTHi pathogenesis. RECENT FINDINGS By using new methodology, such as experimental human colonization models and whole-genome approaches, investigators have shed light upon the various strategies of NTHi that are involved in pathogenesis. These include the escape of the mucociliary elevator, evasion of host immunity, survival in environments with scarce nutrients, and finally participation in polymicrobial infections. Lipooligosaccharide branching, proteinous adhesins, metabolic adaption to nutrient availability and many scavenging systems are implicated in these processes. Interestingly, genome-based studies comparing virulent and commensal strains have identified many hypothetical proteins as virulence determinants, suggesting that much regarding the molecular pathogenesis of NTHi remains to be solved. SUMMARY NTHi is an opportunistic pathogen and highly specialized colonizer of the human respiratory tract that has developed intricate mechanisms to establish growth and survival in the human host. Continued research is needed to further elucidate NTHi host-pathogen and pathogen-pathogen interactions.
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Malhotra R, Olsson H. Immunology, genetics and microbiota in the COPD pathophysiology: potential scope for patient stratification. Expert Rev Respir Med 2015; 9:153-9. [DOI: 10.1586/17476348.2015.1000865] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Overlapping and complementary oxidative stress defense mechanisms in nontypeable Haemophilus influenzae. J Bacteriol 2014; 197:277-85. [PMID: 25368297 DOI: 10.1128/jb.01973-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Gram-negative commensal bacterium nontypeable Haemophilus influenzae (NTHI) can cause respiratory tract diseases that include otitis media, sinusitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. During colonization and infection, NTHI withstands oxidative stress generated by reactive oxygen species produced endogenously, by the host, and by other copathogens and flora. These reactive oxygen species include superoxide, hydrogen peroxide (H2O2), and hydroxyl radicals, whose killing is amplified by iron via the Fenton reaction. We previously identified genes that encode proteins with putative roles in protection of the NTHI isolate strain 86-028NP against oxidative stress. These include catalase (HktE), peroxiredoxin/glutaredoxin (PgdX), and a ferritin-like protein (Dps). Strains were generated with mutations in hktE, pgdX, and dps. The hktE mutant and a pgdX hktE double mutant were more sensitive than the parent to killing by H2O2. Conversely, the pgdX mutant was more resistant to H2O2 due to increased catalase activity. Supporting the role of killing via the Fenton reaction, binding of iron by Dps significantly mitigated the effect of H2O2-mediated killing. NTHI thus utilizes several effectors to resist oxidative stress, and regulation of free iron is critical to this protection. These mechanisms will be important for successful colonization and infection by this opportunistic human pathogen.
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Haemophilus ducreyi RpoE and CpxRA appear to play distinct yet complementary roles in regulation of envelope-related functions. J Bacteriol 2014; 196:4012-25. [PMID: 25201944 DOI: 10.1128/jb.02034-14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Haemophilus ducreyi causes the sexually transmitted disease chancroid and a chronic limb ulceration syndrome in children. In humans, H. ducreyi is found in an abscess and overcomes a hostile environment to establish infection. To sense and respond to membrane stress, bacteria utilize two-component systems (TCSs) and extracytoplasmic function (ECF) sigma factors. We previously showed that activation of CpxRA, the only intact TCS in H. ducreyi, does not regulate homologues of envelope protein folding factors but does downregulate genes encoding envelope-localized proteins, including many virulence determinants. H. ducreyi also harbors a homologue of RpoE, which is the only ECF sigma factor in the organism. To potentially understand how H. ducreyi responds to membrane stress, here we defined RpoE-dependent genes using transcriptome sequencing (RNA-Seq). We identified 180 RpoE-dependent genes, of which 98% were upregulated; a major set of these genes encodes homologues of envelope maintenance and repair factors. We also identified and validated a putative RpoE promoter consensus sequence, which was enriched in the majority of RpoE-dependent targets. Comparison of RpoE-dependent genes to those controlled by CpxR showed that each transcription factor regulated a distinct set of genes. Given that RpoE activated a large number of genes encoding envelope maintenance and repair factors and that CpxRA represses genes encoding envelope-localized proteins, these data suggest that RpoE and CpxRA appear to play distinct yet complementary roles in regulating envelope homeostasis in H. ducreyi.
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HrrF is the Fur-regulated small RNA in nontypeable Haemophilus influenzae. PLoS One 2014; 9:e105644. [PMID: 25157846 PMCID: PMC4144887 DOI: 10.1371/journal.pone.0105644] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/21/2014] [Indexed: 02/06/2023] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) are Gram-negative commensal bacteria that reside in the nasopharynx. NTHi can also cause multiple upper and lower respiratory tract diseases that include sinusitis, conjunctivitis, bronchitis, and otitis media. In numerous bacterial species the ferric uptake regulator (Fur) acts as a global regulator of iron homeostasis by negatively regulating the expression of iron uptake systems. However in NTHi strain 86-028NP and numerous other bacterial species there are multiple instances where Fur positively affects gene expression. It is known that many instances of positive regulation by Fur occur indirectly through a small RNA intermediate. However, no examples of small RNAs have been described in NTHi. Therefore we used RNA-Seq analysis to analyze the transcriptome of NTHi strain 86-028NPrpsL and an isogenic 86-028NPrpsLΔfur strain to identify Fur-regulated intergenic transcripts. From this analysis we identified HrrF, the first small RNA described in any Haemophilus species. Orthologues of this small RNA exist only among other Pasteurellaceae. Our analysis showed that HrrF is maximally expressed when iron levels are low. Additionally, Fur was shown to bind upstream of the hrrF promoter. RNA-Seq analysis was used to identify targets of HrrF which include genes whose products are involved in molybdate uptake, deoxyribonucleotide synthesis, and amino acid biosynthesis. The stability of HrrF is not dependent on the RNA chaperone Hfq. This study is the first step in an effort to investigate the role small RNAs play in altering gene expression in response to iron limitation in NTHi.
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Bertrand RL. Lag phase-associated iron accumulation is likely a microbial counter-strategy to host iron sequestration: role of the ferric uptake regulator (fur). J Theor Biol 2014; 359:72-9. [PMID: 24929040 DOI: 10.1016/j.jtbi.2014.05.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 05/19/2014] [Accepted: 05/27/2014] [Indexed: 01/26/2023]
Abstract
Iron is an essential metal for almost all forms of life, but potentiates oxidative stress via Fenton catalysis. During microbial lag phase there is a rapid influx of iron with concomitant oxidative hypersensitivity. How and why iron accumulation occurs remains to be elucidated. Iron homeostasis in prokaryotes is mediated by the ferric uptake regulator (Fur), an iron-activated global regulator that controls intracellular iron levels by feedback inhibition with the metal. Herein it is postulated, based on the expression profiles of antioxidant enzymes within the Fur regulon as observed in wild type and Δfur mutants, that iron accumulation is mediated by a transitively low concentration of the Fur protein during lag phase. Vertebrate hosts sequester iron upon 'sensing' an infection in order to retard microbial proliferation through a process known as 'nutritional immunity'. It is herein argued that the purpose of iron accumulation is not principally a preparative step for the replicative phase, as suggested elsewhere, but an evolved behavior that counteracts host iron sequestration. This interpretation is supported by multiple clinical and animal studies that demonstrate that iron surplus in hosts advances progression and susceptibility to infection, and vice versa. Contextualizing iron accumulation as a counter-immune behavior adds impetus to the development of antibiotics targeting pathogenic modes of iron acquisition.
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Affiliation(s)
- Robert L Bertrand
- Department of Chemistry, University of Winnipeg, Winnipeg, MB, Canada R3B 2E9.
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Ishak N, Tikhomirova A, Bent SJ, Ehrlich GD, Hu FZ, Kidd SP. There is a specific response to pH by isolates of Haemophilus influenzae and this has a direct influence on biofilm formation. BMC Microbiol 2014; 14:47. [PMID: 24555828 PMCID: PMC3938079 DOI: 10.1186/1471-2180-14-47] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 02/19/2014] [Indexed: 12/22/2022] Open
Abstract
Background Haemophilus influenzae colonizes the nasopharynx as a commensal. Strain-specific factors allow some strains to migrate to particular anatomical niches, such as the middle ear, bronchi or blood, and induce disease by surviving within the conditions present at these sites in the body. It is established that H. influenzae colonization and in some cases survival is highly dependent on their ability to form a biofilm. Biofilm formation is a key trait in the development of chronic infection by certain isolates. This is exemplified by the contrast between the biofilm-forming strains found in middle ear infections and those isolates that survive within the blood and are rarely associated with biofilm development. Results Screening a group of H. influenzae strains revealed only slight variations in their growth across a range of pH conditions. However, some isolates responded to a pH of 8.0 by the formation of a biofilm. While the type b capsular blood isolate Eagan did not form a biofilm and grew at the same rate regardless of pH 6.8-8.0, transcriptomic analyses demonstrated that at pH 8.0 it uniquely induced a gluconate-uptake and metabolism pathway, which concurrently imports H+. A non-typeable H. influenzae, isolated from the middle ear, induced biofilm formation at pH 8.0, and at this pH it induced a series of iron acquisition genes, consistent with previous studies linking iron homeostasis to biofilm lifestyle. Conclusions Different strains of H. influenzae cope with changes in environmental factors using strain-specific mechanisms. These pathways define the scope and mode of niche-survival for an isolate. The pH is a property that is different from the middle ear (at least pH 8.0) compared to other sites that H. influenzae can colonize and infect. The transcriptional response to increasing pH by H. influenzae varies between strains, and pH is linked to pathways that allow strains to either continue free-living growth or induction of a biofilm. We showed that a biofilm-forming isolate induced iron metabolism pathways, whereas a strain that does not form biofilm at increasing pH induced mechanisms for growth and pH homeostasis based on sugar acid transport.
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Affiliation(s)
| | | | | | | | | | - Stephen P Kidd
- Research Centre for Infectious Diseases, The University of Adelaide, North Terrace Campus, Adelaide, South Australia 5005, Australia.
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Haemophilus responses to nutritional immunity: epigenetic and morphological contribution to biofilm architecture, invasion, persistence and disease severity. PLoS Pathog 2013; 9:e1003709. [PMID: 24130500 PMCID: PMC3795038 DOI: 10.1371/journal.ppat.1003709] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 08/30/2013] [Indexed: 12/18/2022] Open
Abstract
In an effort to suppress microbial outgrowth, the host sequesters essential nutrients in a process termed nutritional immunity. However, inflammatory responses to bacterial insult can restore nutritional resources. Given that nutrient availability modulates virulence factor production and biofilm formation by other bacterial species, we hypothesized that fluctuations in heme-iron availability, particularly at privileged sites, would similarly influence Haemophilus biofilm formation and pathogenesis. Thus, we cultured Haemophilus through sequential heme-iron deplete and heme-iron replete media to determine the effect of transient depletion of internal stores of heme-iron on multiple pathogenic phenotypes. We observed that prior heme-iron restriction potentiates biofilm changes for at least 72 hours that include increased peak height and architectural complexity as compared to biofilms initiated from heme-iron replete bacteria, suggesting a mechanism for epigenetic responses that participate in the changes observed. Additionally, in a co-infection model for human otitis media, heme-iron restricted Haemophilus, although accounting for only 10% of the inoculum (90% heme-iron replete), represented up to 99% of the organisms recovered at 4 days. These data indicate that fluctuations in heme-iron availability promote a survival advantage during disease. Filamentation mediated by a SulA-related ortholog was required for optimal biofilm peak height and persistence during experimental otitis media. Moreover, severity of disease in response to heme-iron restricted Haemophilus was reduced as evidenced by lack of mucosal destruction, decreased erythema, hemorrhagic foci and vasodilatation. Transient restriction of heme-iron also promoted productive invasion events leading to the development of intracellular bacterial communities. Taken together, these data suggest that nutritional immunity, may, in fact, foster long-term phenotypic changes that better equip bacteria for survival at infectious sites. Clinical management of upper and lower respiratory tract diseases caused by nontypeable Haemophilus influenzae (NTHI) is a significant socioeconomic burden. Therapies targeting the pathogenic lifestyle of NTHI remain non-existent due to a lack of understanding of host microenvironmental cues and bacterial responses that dictate NTHI persistence. Iron availability influences bacterial virulence traits and biofilm formation; yet, host sequestration of iron serves to restrict bacterial growth. We predicted that fluctuations in availability of iron-containing compounds, typically associated with infection, would impact NTHI pathogenesis. We demonstrated that transient restriction of heme-iron triggered an epigenetic developmental program that enhanced NTHI biofilm architecture, directly influenced by induced morphological changes in bacterial length. Heme-iron restricted bacteria were primed for survival in the mammalian middle ear, due in part to an observed reduction in host inflammation coinciding with a striking reduction in host mucosal epithelial damage, compared to that observed in response to heme-iron replete NTHI. Moreover, transiently restricted NTHI were more invasive of epithelial cells resulting in formation of intracellular bacterial communities. Our findings significantly advance our understanding of how host immune pressure and nutrient availability influence pathogenic behaviors that impact disease severity.
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Runyen-Janecky LJ. Role and regulation of heme iron acquisition in gram-negative pathogens. Front Cell Infect Microbiol 2013; 3:55. [PMID: 24116354 PMCID: PMC3792355 DOI: 10.3389/fcimb.2013.00055] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/10/2013] [Indexed: 12/14/2022] Open
Abstract
Bacteria that reside in animal tissues and/or cells must acquire iron from their host. However, almost all of the host iron is sequestered in iron-containing compounds and proteins, the majority of which is found within heme molecules. Thus, likely iron sources for bacterial pathogens (and non-pathogenic symbionts) are free heme and heme-containing proteins. Furthermore, the cellular location of the bacterial within the host (intra or extracellular) influences the amount and nature of the iron containing compounds available for transport. The low level of free iron in the host, coupled with the presence of numerous different heme sources, has resulted in a wide range of high-affinity iron acquisition strategies within bacteria. However, since excess iron and heme are toxic to bacteria, expression of these acquisition systems is highly regulated. Precise expression in the correct host environment at the appropriate times enables heme iron acquisitions systems to contribute to the growth of bacterial pathogens within the host. This mini-review will highlight some of the recent findings in these areas for gram-negative pathogens.
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Troxell B, Hassan HM. Transcriptional regulation by Ferric Uptake Regulator (Fur) in pathogenic bacteria. Front Cell Infect Microbiol 2013; 3:59. [PMID: 24106689 PMCID: PMC3788343 DOI: 10.3389/fcimb.2013.00059] [Citation(s) in RCA: 290] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 09/18/2013] [Indexed: 12/16/2022] Open
Abstract
In the ancient anaerobic environment, ferrous iron (Fe2+) was one of the first metal cofactors. Oxygenation of the ancient world challenged bacteria to acquire the insoluble ferric iron (Fe3+) and later to defend against reactive oxygen species (ROS) generated by the Fenton chemistry. To acquire Fe3+, bacteria produce low-molecular weight compounds, known as siderophores, which have extremely high affinity for Fe3+. However, during infection the host restricts iron from pathogens by producing iron- and siderophore-chelating proteins, by exporting iron from intracellular pathogen-containing compartments, and by limiting absorption of dietary iron. Ferric Uptake Regulator (Fur) is a transcription factor which utilizes Fe2+ as a corepressor and represses siderophore synthesis in pathogens. Fur, directly or indirectly, controls expression of enzymes that protect against ROS damage. Thus, the challenges of iron homeostasis and defense against ROS are addressed via Fur. Although the role of Fur as a repressor is well-documented, emerging evidence demonstrates that Fur can function as an activator. Fur activation can occur through three distinct mechanisms (1) indirectly via small RNAs, (2) binding at cis regulatory elements that enhance recruitment of the RNA polymerase holoenzyme (RNAP), and (3) functioning as an antirepressor by removing or blocking DNA binding of a repressor of transcription. In addition, Fur homologs control defense against peroxide stress (PerR) and control uptake of other metals such as zinc (Zur) and manganese (Mur) in pathogenic bacteria. Fur family members are important for virulence within bacterial pathogens since mutants of fur, perR, or zur exhibit reduced virulence within numerous animal and plant models of infection. This review focuses on the breadth of Fur regulation in pathogenic bacteria.
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Affiliation(s)
- Bryan Troxell
- Department of Immunology and Microbiology, Indiana University School of Medicine Indianapolis, IN, USA
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