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Ye D, Nguyen PT, Bourgault S, Couture M. The heme binding protein ChuX is a regulator of heme degradation by the ChuS protein in Escherichia coli O157:H7. J Inorg Biochem 2024; 256:112575. [PMID: 38678912 DOI: 10.1016/j.jinorgbio.2024.112575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/01/2024]
Abstract
Escherichia coli O157:H7 possesses an 8-gene cluster (chu genes) that contains genes involved in heme transport and processing from the human host. Among the chu genes, four encode cytoplasmic proteins (ChuS, ChuX, ChuY and ChuW). ChuX was previously shown to be a heme binding protein and to assist ChuW in heme degradation under anaerobic conditions. The purpose of this work was to investigate if ChuX works in concert with ChuS, which is a protein able to degrade heme by a non-canonical mechanism and release the iron from the porphyrin under aerobic conditions using hydrogen peroxide as the oxidant. We showed that when the heme-bound ChuX and apo-ChuS protein are mixed, heme is efficiently transferred from ChuX to ChuS. Heme-bound ChuX displayed a peroxidase activity with ABTS and H2O2 but not heme-bound ChuS, which is an efficient test to determine the protein to which heme is bound in the ChuS-ChuX complex. We found that ChuX protects heme from chemical oxidation and that it has no heme degradation activity by itself. Unexpectedly, we found that ChuX inhibits heme degradation by ChuS and stops the reaction at an early intermediate. We determined using surface plasmon resonance that ChuX interacts with ChuS and that it forms a relatively stable complex. These results indicate that ChuX in addition to its heme transfer activity is a regulator of ChuS activity, a function that was not described before for any of the heme carrier protein that delivers heme to heme degradation enzymes.
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Affiliation(s)
- Danrong Ye
- Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec City, QC, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS) and PROTEO, Université Laval, Quebec city, QC, Canada; Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada
| | - Phuong Trang Nguyen
- Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada; Departement of Chemistry, Université du Québec à Montréal, Montreal, QC, Canada
| | - Steve Bourgault
- Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada; Departement of Chemistry, Université du Québec à Montréal, Montreal, QC, Canada
| | - Manon Couture
- Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec City, QC, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS) and PROTEO, Université Laval, Quebec city, QC, Canada; Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada.
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2
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Liu N, Gonzalez TA, Fischer J, Hong C, Johnson M, Mawhorter R, Mugnatto F, Soh R, Somji S, Wirth JS, Libeskind-Hadas R, Bush EC. xenoGI 3: using the DTLOR model to reconstruct the evolution of gene families in clades of microbes. BMC Bioinformatics 2023; 24:295. [PMID: 37480009 PMCID: PMC10362622 DOI: 10.1186/s12859-023-05410-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 07/11/2023] [Indexed: 07/23/2023] Open
Abstract
To understand genome evolution in a group of microbes, we need to know the timing of events such as duplications, deletions and horizontal transfers. A common approach is to perform a gene-tree / species-tree reconciliation. While a number of software packages perform this type of analysis, none are geared toward a complete reconstruction for all families in an entire clade. Here we describe an update to the xenoGI software package which allows users to perform such an analysis using the newly developed DTLOR (duplication-transfer-loss-origin-rearrangement) reconciliation model starting from genome sequences as input.
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Affiliation(s)
- Nuo Liu
- Department of Biology, Harvey Mudd College, Claremont, CA, USA
| | | | - Jacob Fischer
- Department of Computer Science, Harvey Mudd College, Claremont, CA, USA
| | - Chan Hong
- Department of Biology, Harvey Mudd College, Claremont, CA, USA
| | | | - Ross Mawhorter
- Department of Computer Science and Engineering, University of California Santa Cruz, Santa Cruz, CA, USA
| | | | - Rachael Soh
- Department of Biology, Harvey Mudd College, Claremont, CA, USA
| | - Shifa Somji
- Department of Computer Science, Harvey Mudd College, Claremont, CA, USA
| | - Joseph S Wirth
- Department of Biology, Harvey Mudd College, Claremont, CA, USA
- Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Ran Libeskind-Hadas
- Department of Integrated Sciences, Claremont McKenna College, Claremont, CA, USA
| | - Eliot C Bush
- Department of Biology, Harvey Mudd College, Claremont, CA, USA.
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3
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Sy BM, Tree JJ. The Small RNA CyaR Activates Translation of the Outer Membrane Haem Receptor chuA in Enterohemorrhagic Escherichia coli. Front Microbiol 2022; 13:821196. [PMID: 35422774 PMCID: PMC9002310 DOI: 10.3389/fmicb.2022.821196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/10/2022] [Indexed: 12/22/2022] Open
Abstract
To sense the transition from environment to host, bacteria use a range of environmental cues to control expression of virulence genes. Iron is tightly sequestered in host tissues and in the human pathogen enterohemorrhagic Escherichia coli (EHEC) iron-limitation induces transcription of the outer membrane haem transporter encoded by chuAS. ChuA expression is post-transcriptionally activated at 37°C by a FourU RNA thermometer ensuring that the haem receptor is only expressed under low iron, high temperature conditions that indicate the host. Here we demonstrate that expression of chuA is also independently regulated by the cAMP-responsive small RNA (sRNA) CyaR and transcriptional terminator Rho. These results indicate that chuAS expression is regulated at the transcription initiation, transcript elongation, and translational level. We speculate that additional sensing of the gluconeogenic environment allows further precision in determining when EHEC is at the gastrointestinal epithelium of the host. With previous studies, it appears that the chuAS transcript is controlled by eight regulatory inputs that control expression through six different transcriptional and post-transcriptional mechanisms. The results highlight the ability of regulatory sRNAs to integrate multiple environmental signals into a layered hierarchy of signal input.
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Affiliation(s)
- Brandon M Sy
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Jai J Tree
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
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4
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Abstract
Iron is an essential element for Escherichia, Salmonella, and Shigella species. The acquisition of sufficient amounts of iron is difficult in many environments, including the intestinal tract, where these bacteria usually reside. Members of these genera have multiple iron transport systems to transport both ferrous and ferric iron. These include transporters for free ferrous iron, ferric iron associated with chelators, and heme. The numbers and types of transport systems in any species reflect the diversity of niches that it can inhabit. Many of the iron transport genes are found on mobile genetic elements or pathogenicity islands, and there is evidence of the spread of the genes among different species and pathotypes. This is notable among the pathogenic members of the genera in which iron transport systems acquired by horizontal gene transfer allow the bacteria to overcome host innate defenses that act to restrict the availability of iron to the pathogen. The need for iron is balanced by the need to avoid iron overload since excess iron is toxic to the cell. Genes for iron transport and metabolism are tightly regulated and respond to environmental cues, including iron availability, oxygen, and temperature. Master regulators, the iron sensor Fur and the Fur-regulated small RNA (sRNA) RyhB, coordinate the expression of iron transport and cellular metabolism genes in response to the availability of iron.
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5
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Pasquali F, Schinzari M, Lucchi A, Mandrioli M, Toschi TG, De Cesare A, Manfreda G. Preliminary data on the antimicrobial effect of Cannabis sativa L. variety Futura 75 against food-borne pathogens in vitro as well as against naturally occurring microbial populations on minced meat during storage. Ital J Food Saf 2020; 9:8581. [PMID: 32913724 PMCID: PMC7459756 DOI: 10.4081/ijfs.2020.8581] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023] Open
Abstract
In the present study, the antimicrobial effect of Cannabis sativa Futura 75 was evaluated both in vitro against foodborne bacterial pathogens, and on food against naturally occurring microbial groups of minced meat stored for 8 days at 4°C. Ethanol extraction was performed on the grind of the inflorescence. After extraction, ethanol was completely evaporated and substituted by water. Serial dilutions of the extract, the grind and cannabidiol 99% were added to Nutrient Agar and spotted with Listeria monocytogenes, Salmonella Typhimurium, Escherichia coli and Staphylococcus spp. Regarding the evaluation on food, 50 mL of extract, characterised by CBD at concentration of 322,70 μg/mL, were added to 2.5 kg of minced beef meat. Meat was divided into aliquots and stored for 8 days at 4°C. At 0, 1, 2, 3, 4, 7, and 8 days, aerobic bacteria, enterobacteria, coliforms and E. coli were enumerated. All tested products were efficient against Gram +. In particular, extract corresponding to CBD concentration of 0.017 and 0.3 mg/mL were effective against L. monocytogenes and Staphylococcus spp. respectively. After 8 days of storage at 4°C, treated minced meat showed a bright red colour in comparison to a brownish control meat. Moreover, Enterobacteriaceae and coliforms were significantly reduced of 2.3 log CFU/g and 1.6 log CFU/g respectively in treated meat in comparison to the control. Although preliminary, the present study suggests the antimicrobial properties of the extract of Cannabis sativa both in vitro and in minced meat.
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Affiliation(s)
| | - Marco Schinzari
- Department of Agricultural and Food Sciences, University of Bologna, Italy
| | - Alex Lucchi
- Department of Agricultural and Food Sciences, University of Bologna, Italy
| | - Mara Mandrioli
- Department of Agricultural and Food Sciences, University of Bologna, Italy
| | | | | | - Gerardo Manfreda
- Department of Agricultural and Food Sciences, University of Bologna, Italy
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6
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The role of major virulence factors and pathogenicity of adherent-invasive Escherichia coli in patients with Crohn's disease. GASTROENTEROLOGY REVIEW 2020; 15:279-288. [PMID: 33777266 PMCID: PMC7988836 DOI: 10.5114/pg.2020.93235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 11/04/2019] [Indexed: 12/12/2022]
Abstract
Inflammatory bowel disease (IBD) is a term that describes Crohn's disease (CD) and ulcerative colitis (UC), and these two conditions are characterised by chronic inflammation of the gastrointestinal tract. Dysbiosis of intestinal microbiota has been consistently linked to patients with IBD. In the last two decades, the progressive implication of adherent-invasive Escherichia coli (AIEC) pathogenesis in patients with CD has been increasing. Here we discuss recent findings that indicate the role and mechanisms of AIEC in IBD. We also highlight AIEC virulence factor genes and mechanisms that suggest an important role in the severity of inflammation in CD patients. Finally, we emphasise data on the prevalence of AIEC in CD patients.
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7
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Jin WB, Wu S, Xu YF, Yuan H, Tang GL. Recent advances in HemN-like radical S-adenosyl-l-methionine enzyme-catalyzed reactions. Nat Prod Rep 2020; 37:17-28. [DOI: 10.1039/c9np00032a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
HemN-like radical S-adenosyl-l-methionine (SAM) enzymes have been recently disclosed to catalyze diverse chemically challenging reactions from primary to secondary metabolic pathways.
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Affiliation(s)
- Wen-Bing Jin
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Sheng Wu
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Yi-Fan Xu
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Hua Yuan
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Gong-Li Tang
- State Key Laboratory of Bio-organic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
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8
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Brons JK, Vink SN, de Vos MGJ, Reuter S, Dobrindt U, van Elsas JD. Fast identification of Escherichia coli in urinary tract infections using a virulence gene based PCR approach in a novel thermal cycler. J Microbiol Methods 2019; 169:105799. [PMID: 31790780 DOI: 10.1016/j.mimet.2019.105799] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/29/2019] [Accepted: 11/29/2019] [Indexed: 01/20/2023]
Abstract
Uropathogenic Escherichia coli (UPEC) is the most common causal agent of urinary tract infections (UTIs) in humans. Currently, clinical detection methods take hours (dipsticks) to days (culturing methods), limiting rapid intervention. As an alternative, the use of molecular methods could improve speed and accuracy, but their applicability is complicated by high genomic variability within UPEC strains. Here, we describe a novel PCR-based method for the identification of E. coli in urine. Based on in silico screening of UPEC genomes, we selected three UPEC-specific genes predicted to be involved in pathogenesis (c3509, c3686 (yrbH) and chuA), and one E. coli-specific marker gene (uidA). We validated the method on 128 clinical (UTI) strains. Despite differential occurrences of these genes in uropathogenic E. coli, the method, when using multi-gene combinations, specifically detected the target organism across all samples. The lower detection limit, assessed with model UPEC strains, was approximately 104 CFU/ml. Additionally, the use of this method in a novel ultrafast PCR thermal cycler (Nextgen PCR) allowed a detection time from urine sampling to identification of only 52 min. This is the first study that uses such defined sets of marker genes for the detection of E. coli in UTIs. In addition, we are the first to demonstrate the potential of the Nextgen thermal cycler. Our E. coli identification method has the potential to be a rapid, reliable and inexpensive alternative for traditional methods.
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Affiliation(s)
- Jolanda K Brons
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
| | - Stefanie N Vink
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Marjon G J de Vos
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Stefan Reuter
- Department of Medicine D, Division of General Internal Medicine, Nephrology and Rheumatology, University Hospital of Münster, Münster, Germany
| | - Ulrich Dobrindt
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Jan Dirk van Elsas
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
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9
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Shi YJ, Fang QJ, Huang HQ, Gong CG, Hu YH. HutZ is required for biofilm formation and contributes to the pathogenicity of Edwardsiella piscicida. Vet Res 2019; 50:76. [PMID: 31578154 PMCID: PMC6775658 DOI: 10.1186/s13567-019-0693-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/19/2019] [Indexed: 12/13/2022] Open
Abstract
Edwardsiella piscicida is a severe fish pathogen. Haem utilization systems play an important role in bacterial adversity adaptation and pathogenicity. In this study, a speculative haem utilization protein, HutZEp, was characterized in E. piscicida. hutZEp is encoded with two other genes, hutW and hutX, in an operon that is similar to the haem utilization operon hutWXZ identified in V. cholerae. However, protein activity analysis showed that HutZEp is probably not related to hemin utilization. To explore the biological role of HutZEp, a markerless hutZEp in-frame mutant strain, TX01ΔhutZ, was constructed. Deletion of hutZEp did not significantly affect bacterial growth in normal medium, in iron-deficient conditions, or in the presence of haem but significantly retarded bacterial biofilm growth. The expression of known genes related to biofilm growth was not affected by hutZEp deletion, which indicated that HutZEp was probably a novel factor promoting biofilm formation in E. piscicida. Compared to the wild-type TX01, TX01ΔhutZ exhibited markedly compromised tolerance to acid stress and host serum stress. Pathogenicity analysis showed that inactivation of hutZEp significantly impaired the ability of E. piscicida to invade and reproduce in host cells and to infect host tissue. In contrast to TX01, TX01ΔhutZ was defective in blocking host macrophage activation. The expression of hutZEp was directly regulated by the ferric uptake regulator Fur. This study is the first functional characterization of HutZ in a fish pathogen, and these findings suggested that HutZEp is essential for E. piscicida biofilm formation and contributes to host infection.
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Affiliation(s)
- Yan-Jie Shi
- Ocean College of Hebei Agricultural University, Qinhuangdao, 066000, China.,Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Qing-Jian Fang
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Hui-Qin Huang
- Ocean College of Hebei Agricultural University, Qinhuangdao, 066000, China.,Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China.,Hainan Provincial Key Laboratory for Functional Components Research and Utilization of Marine Bio-resources, Haikou, 571101, China
| | - Chun-Guang Gong
- Ocean College of Hebei Agricultural University, Qinhuangdao, 066000, China.
| | - Yong-Hua Hu
- Ocean College of Hebei Agricultural University, Qinhuangdao, 066000, China. .,Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China. .,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China. .,Hainan Provincial Key Laboratory for Functional Components Research and Utilization of Marine Bio-resources, Haikou, 571101, China.
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10
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Pasquali F, Palma F, Trevisani M, Parisi A, Lucchi A, Cesare AD, Manfreda G. Whole genome sequencing based typing and characterisation of Shiga-toxin producing Escherichia coli strains belonging to O157 and O26 serotypes and isolated in dairy farms. Ital J Food Saf 2018; 7:7673. [PMID: 30854339 PMCID: PMC6379698 DOI: 10.4081/ijfs.2018.7673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 10/22/2018] [Indexed: 01/16/2023] Open
Abstract
In the present study, the genetic relationships as well as the virulome and resistome of newly sequenced O26 and O157 Shiga-toxin producing E. coli (STEC) isolates, collected from dairy farms in Italy, were investigated in comparison to publicly available genomes collected worldwide. The whole genome of Italian isolates was sequenced on Illumina MiSeq Platform. Reads quality control, de novo draft genome assembly, species confirmation and the 7- loci Multi-Locus Sequence Type assignment were performed using INNUca pipeline. Reference-based SNPs calling was performed on O157 and O26 genomes, separately, mapping contigs to high-quality finished genomes. Virulence and antimicrobial resistance determinants were detected in silico using the tool ABRicate. Phylogenetic reconstructions revealed that genomes clustered mainly based on their 7-loci MLST type. The virulome of tested genomes included 190 determinants. O157 genomes carried chu genes associated to heme mediated iron uptake, whereas O26 genomes harboured genes ybt associated to siderophore mediated iron uptake. Resistome analysis showed the presence of tet(34) on all but one O157 genomes and on only one O26 genomes. Only 4 genomes carried genes associated to multiresistance. In the present study, the genes chu and ybt were identified as potential biomarker for the differentiation of O157 and O26 serotypes.
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Affiliation(s)
- Frederique Pasquali
- Department of Agricultural and Food Sciences, Alma Mater Studiorum – University of Bologna
| | - Federica Palma
- Department of Agricultural and Food Sciences, Alma Mater Studiorum – University of Bologna
| | - Marcello Trevisani
- Department of Veterinary Medical Sciences, Alma Mater Studiorum – University of Bologna
| | - Antonio Parisi
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Bari, Italy
| | - Alex Lucchi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum – University of Bologna
| | - Alessandra De Cesare
- Department of Agricultural and Food Sciences, Alma Mater Studiorum – University of Bologna
| | - Gerardo Manfreda
- Department of Agricultural and Food Sciences, Alma Mater Studiorum – University of Bologna
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11
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Franco M, D'haeseleer PM, Branda SS, Liou MJ, Haider Y, Segelke BW, El-Etr SH. Proteomic Profiling of Burkholderia thailandensis During Host Infection Using Bio-Orthogonal Noncanonical Amino Acid Tagging (BONCAT). Front Cell Infect Microbiol 2018; 8:370. [PMID: 30406044 PMCID: PMC6206043 DOI: 10.3389/fcimb.2018.00370] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/03/2018] [Indexed: 01/01/2023] Open
Abstract
Burkholderia pseudomallei and B. mallei are the causative agents of melioidosis and glanders, respectively, and are often fatal to humans and animals. Owing to the high fatality rate, potential for spread by aerosolization, and the lack of efficacious therapeutics, B. pseudomallei and B. mallei are considered biothreat agents of concern. In this study, we investigate the proteome of Burkholderia thailandensis, a closely related surrogate for the two more virulent Burkholderia species, during infection of host cells, and compare to that of B. thailandensis in culture. Studying the proteome of Burkholderia spp. during infection is expected to reveal molecular mechanisms of intracellular survival and host immune evasion; but proteomic profiling of Burkholderia during host infection is challenging. Proteomic analyses of host-associated bacteria are typically hindered by the overwhelming host protein content recovered from infected cultures. To address this problem, we have applied bio-orthogonal noncanonical amino acid tagging (BONCAT) to B. thailandensis, enabling the enrichment of newly expressed bacterial proteins from virtually any growth condition, including host cell infection. In this study, we show that B. thailandensis proteins were selectively labeled and efficiently enriched from infected host cells using BONCAT. We also demonstrate that this method can be used to label bacteria in situ by fluorescent tagging. Finally, we present a global proteomic profile of B. thailandensis as it infects host cells and a list of proteins that are differentially regulated in infection conditions as compared to bacterial monoculture. Among the identified proteins are quorum sensing regulated genes as well as homologs to previously identified virulence factors. This method provides a powerful tool to study the molecular processes during Burkholderia infection, a much-needed addition to the Burkholderia molecular toolbox.
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Affiliation(s)
- Magdalena Franco
- Lawrence Livermore National Laboratory, Livermore, CA, United States
| | | | | | - Megan J Liou
- Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Yasmeen Haider
- Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Brent W Segelke
- Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Sahar H El-Etr
- Lawrence Livermore National Laboratory, Livermore, CA, United States
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12
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Jaworska K, Nieckarz M, Ludwiczak M, Raczkowska A, Brzostek K. OmpR-Mediated Transcriptional Regulation and Function of Two Heme Receptor Proteins of Yersinia enterocolitica Bio-Serotype 2/O:9. Front Cell Infect Microbiol 2018; 8:333. [PMID: 30294593 PMCID: PMC6158557 DOI: 10.3389/fcimb.2018.00333] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 08/29/2018] [Indexed: 12/26/2022] Open
Abstract
We show that Yersinia enterocolitica strain Ye9 (bio-serotype 2/O:9) utilizes heme-containing molecules as an iron source. The Ye9 genome contains two multigenic clusters, hemPRSTUV-1 and hemPRST-2, encoding putative heme receptors HemR1 and HemR2, that share 62% amino acid identity. Expression of these proteins in an Escherichia coli mutant defective in heme biosynthesis allowed this strain to use hemin and hemoglobin as a source of porphyrin. The hemPRSTUV-1 and hemPRST-2 clusters are organized as operons, expressed from the phem−1 and weaker phem−2 promoters, respectively. Expression of both operons is negatively regulated by iron and the iron-responsive transcriptional repressor Fur. In addition, OmpR, the response regulator of two component system (TCSs) EnvZ/OmpR, represses transcription of both operons through interaction with binding sequences overlapping the −35 region of their promoters. Western blot analysis of the level of HemR1 in ompR, fur, and ompRfur mutants, showed an additive effect of these mutations, indicating that OmpR may regulate HemR expression independently of Fur. However, the effect of OmpR on the activity of the phem−1 promoter and on HemR1 production was observed in both iron-depleted and iron-replete conditions, i.e., when Fur represses the iron-regulated promoter. In addition, a hairpin RNA thermometer, composed of four uracil residues (FourU) that pair with the ribosome-binding site in the 5′-untranslated region (5′-UTR) of hemR1 was predicted by in silico analysis. However, thermoregulated expression of HemR1 could not be demonstrated. Taken together, these data suggest that Fur and OmpR control iron/heme acquisition via a complex mechanism based on negative regulation of hemR1 and hemR2 at the transcriptional level. This interplay could fine-tune the level of heme receptor proteins to allow Y. enterocolitica to fulfill its iron/heme requirements without over-accumulation, which might be important for pathogenic growth within human hosts.
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Affiliation(s)
- Karolina Jaworska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Marta Nieckarz
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Marta Ludwiczak
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Adrianna Raczkowska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Katarzyna Brzostek
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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13
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Robinson AE, Heffernan JR, Henderson JP. The iron hand of uropathogenic Escherichia coli: the role of transition metal control in virulence. Future Microbiol 2018; 13:745-756. [PMID: 29870278 DOI: 10.2217/fmb-2017-0295] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The role of iron as a critical nutrient in pathogenic bacteria is widely regarded as having driven selection for iron acquisition systems among uropathogenic Escherichia coli (UPEC) isolates. Carriage of multiple transition metal acquisition systems in UPEC suggests that the human urinary tract manipulates metal-ion availability in many ways to resist infection. For siderophore systems in particular, recent studies have identified new roles for siderophore copper binding as well as production of siderophore-like inhibitors of iron uptake by other, competing bacterial species. Among these is a process of nutritional passivation of metal ions, in which uropathogens access these vital nutrients while simultaneously protecting themselves from their toxic potential. Here, we review these new findings within the current understanding of UPEC transition metal acquisition.
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Affiliation(s)
- Anne E Robinson
- Division of Infectious Diseases, Department of Medicine, Department of Molecular Microbiology, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - James R Heffernan
- Division of Infectious Diseases, Department of Medicine, Department of Molecular Microbiology, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jeffrey P Henderson
- Division of Infectious Diseases, Department of Medicine, Department of Molecular Microbiology, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
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14
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Abduljalil JM. Bacterial riboswitches and RNA thermometers: Nature and contributions to pathogenesis. Noncoding RNA Res 2018; 3:54-63. [PMID: 30159440 PMCID: PMC6096418 DOI: 10.1016/j.ncrna.2018.04.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/10/2018] [Accepted: 04/10/2018] [Indexed: 12/31/2022] Open
Abstract
Bacterial pathogens are always challenged by fluctuations of chemical and physical parameters that pose serious threats to cellular integrity and metabolic status. Sudden deprivation of nutrients or key metabolites, changes in surrounding pH, and temperature shifts are the most important examples of such parameters. To elicit a proper response to such fluctuations, bacterial cells coordinate the expression of parameter-relevant genes. Although protein-mediated control of gene expression is well appreciated since many decades, RNA-based regulation has been discovered in early 2000s as a parallel level of regulation. Small regulatory RNAs have emerged as one of the most widespread and important gene regulatory systems in bacteria with rare representatives found in Archaea and Eukarya. Riboswitches and thermosensors are cis-encoded RNA regulatory elements that employ different mechanisms to regulate the expression of related genes controlling key metabolic pathways and genes of temperature relevant proteins including virulence factors. The extent of RNA contributions to gene regulation is not completely known even in well-studied models such E. coli and B. subtilis. In depth understanding of riboswitches is promising for opportunity to discover a narrow spectrum antibacterial drugs that target riboswitches of essential metabolic pathways.
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Key Words
- 5ʹ-UTRs, 5ʹ-untranslated region
- AdoCbl, adenosylcobalamine
- Aptamer
- Bacterial pathogenicity
- CSPs, Cold Shock Proteins
- FMN, Flavin mononucleotide
- Gene expression
- ORFs, open reading frames
- RBS, Ribosomal Binding Site
- RNA thermometer
- RNAP, RNA polymerase
- RNAT, RNA thermometer
- Riboswitches
- SAH, S-adenosylhomocysteine
- SAM, S-adenosylmethionine
- SD, Shine-Dalgarno
- TPP, Thiamine pyrophosphate
- Transcription termination
- Virulence
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15
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Bush EC, Clark AE, DeRanek CA, Eng A, Forman J, Heath K, Lee AB, Stoebel DM, Wang Z, Wilber M, Wu H. xenoGI: reconstructing the history of genomic island insertions in clades of closely related bacteria. BMC Bioinformatics 2018; 19:32. [PMID: 29402213 PMCID: PMC5799925 DOI: 10.1186/s12859-018-2038-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
Background Genomic islands play an important role in microbial genome evolution, providing a mechanism for strains to adapt to new ecological conditions. A variety of computational methods, both genome-composition based and comparative, have been developed to identify them. Some of these methods are explicitly designed to work in single strains, while others make use of multiple strains. In general, existing methods do not identify islands in the context of the phylogeny in which they evolved. Even multiple strain approaches are best suited to identifying genomic islands that are present in one strain but absent in others. They do not automatically recognize islands which are shared between some strains in the clade or determine the branch on which these islands inserted within the phylogenetic tree. Results We have developed a software package, xenoGI, that identifies genomic islands and maps their origin within a clade of closely related bacteria, determining which branch they inserted on. It takes as input a set of sequenced genomes and a tree specifying their phylogenetic relationships. Making heavy use of synteny information, the package builds gene families in a species-tree-aware way, and then attempts to combine into islands those families whose members are adjacent and whose most recent common ancestor is shared. The package provides a variety of text-based analysis functions, as well as the ability to export genomic islands into formats suitable for viewing in a genome browser. We demonstrate the capabilities of the package with several examples from enteric bacteria, including an examination of the evolution of the acid fitness island in the genus Escherichia. In addition we use output from simulations and a set of known genomic islands from the literature to show that xenoGI can accurately identify genomic islands and place them on a phylogenetic tree. Conclusions xenoGI is an effective tool for studying the history of genomic island insertions in a clade of microbes. It identifies genomic islands, and determines which branch they inserted on within the phylogenetic tree for the clade. Such information is valuable because it helps us understand the adaptive path that has produced living species. Electronic supplementary material The online version of this article (10.1186/s12859-018-2038-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eliot C Bush
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA.
| | - Anne E Clark
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA.,Current address: Department of Genome Sciences, University of Washington, 3720 15th Ave NE, Seattle, 98195-5065, WA, USA
| | - Carissa A DeRanek
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA
| | - Alexander Eng
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA.,Current address: Department of Genome Sciences, University of Washington, 3720 15th Ave NE, Seattle, 98195-5065, WA, USA
| | - Juliet Forman
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA
| | - Kevin Heath
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA.,Current address: Department of Biology and Biotechnology, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, 01609, MA, USA
| | - Alexander B Lee
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA.,Current address: Quantitative Biosciences Program, Georgia Institute of Technology, 837 State Street, Atlanta, 30332-0430, GA, USA
| | - Daniel M Stoebel
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA
| | - Zunyan Wang
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA
| | - Matthew Wilber
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA
| | - Helen Wu
- Department of Biology, Harvey Mudd College, 301 Platt Blvd., Claremont, 91711, CA, USA
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16
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Abstract
Iron is an essential micronutrient for both microbes and humans alike. For well over half a century we have known that this element, in particular, plays a pivotal role in health and disease and, most especially, in shaping host-pathogen interactions. Intracellular iron concentrations serve as a critical signal in regulating the expression not only of high-affinity iron acquisition systems in bacteria, but also of toxins and other noted virulence factors produced by some major human pathogens. While we now are aware of many strategies that the host has devised to sequester iron from invading microbes, there are as many if not more sophisticated mechanisms by which successful pathogens overcome nutritional immunity imposed by the host. This review discusses some of the essential components of iron sequestration and scavenging mechanisms of the host, as well as representative Gram-negative and Gram-positive pathogens, and highlights recent advances in the field. Last, we address how the iron acquisition strategies of pathogenic bacteria may be exploited for the development of novel prophylactics or antimicrobials.
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17
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Wei Y, Kouse AB, Murphy ER. Transcriptional and posttranscriptional regulation of Shigella shuT in response to host-associated iron availability and temperature. Microbiologyopen 2017; 6. [PMID: 28127899 PMCID: PMC5458455 DOI: 10.1002/mbo3.442] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 11/29/2016] [Accepted: 12/12/2016] [Indexed: 12/17/2022] Open
Abstract
Like most bacteria, Shigella must maintain a precise balance between the necessity and toxicity of iron; a balance that is achieved, at least in part, by regulating the production of bacterial iron acquisition systems in response to specific environmental signals. Using the Shigella heme utilization (Shu) system, S. dysenteriae is able to acquire iron from heme, a potentially rich source of nutritional iron within the otherwise iron-limited environment of the human host. Investigations presented within reveal two distinct molecular mechanisms underlying previously uncharacterized transcriptional and translational regulation of shuT, a gene encoding the periplasmic-binding component of the Shu system. While shuT transcription is regulated in response to iron availability via a process dependent upon the global regulator Fur and a Fur-binding site located immediately downstream of the promoter, shuT translation is regulated in response to environmental temperature via the activity of an RNA thermometer located within the 5' untranslated region of the gene. Such complex regulation likely increases the fitness of S. dysenteriae by ensuring maximal ShuT production when the pathogen is within the iron-limited and relatively warm environment of the infected host, the only environment in which heme will be encountered as a potential source of essential iron.
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Affiliation(s)
- Yahan Wei
- Department of Biological Sciences, Ohio University, Athens, OH, USA
| | - Andrew B Kouse
- Cell Biology and Metabolism Program, NICHD, NIH, Bethesda, MD, USA
| | - Erin R Murphy
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, OH, USA
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18
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Kim H, Chaurasia AK, Kim T, Choi J, Ha SC, Kim D, Kim KK. Structural and functional study of ChuY from Escherichia coli strain CFT073. Biochem Biophys Res Commun 2016; 482:1176-1182. [PMID: 27919686 DOI: 10.1016/j.bbrc.2016.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 12/02/2016] [Indexed: 10/20/2022]
Abstract
The uropathogenic Escherichia coli strain CFT073 contains multiple iron and heme transport systems, which facilitate infection of the host urinary tract. To elucidate the molecular and cellular function of ChuY, a hypothetical gene in the heme degradation/utilization pathway, we solved the crystal structure of ChuY at 2.4 Å resolution. ChuY has high structural homology with human biliverdin and flavin reductase. We confirmed that ChuY has flavin mononucleotide (FMN) reductase activity, using NAD(P)H as a cofactor, and shows porphyrin ring binding affinity. A chuY deletion-insertion strain showed reduced survival potential compared to wild-type and complemented strains in mammalian cells. Current results suggest ChuY acts as a reductase in heme homeostasis to maintain the virulence potential of E. coli CFT073.
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Affiliation(s)
- Hun Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi 16419, South Korea
| | - Akhilesh Kumar Chaurasia
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi 16419, South Korea
| | - Truc Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi 16419, South Korea
| | - Jongkeun Choi
- Department of Cosmetic Science, Chungwoon University, Hongseong, Chungnam 32244, South Korea
| | - Sung Chul Ha
- Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Doyoun Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi 16419, South Korea
| | - Kyeong Kyu Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi 16419, South Korea.
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19
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Maharshak N, Ryu HS, Fan TJ, Onyiah JC, Schulz S, Otterbein SL, Wong R, Hansen JJ, Otterbein LE, Carroll IM, Plevy SE. Escherichia coli heme oxygenase modulates host innate immune responses. Microbiol Immunol 2016; 59:452-65. [PMID: 26146866 DOI: 10.1111/1348-0421.12282] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 06/24/2015] [Accepted: 06/28/2015] [Indexed: 12/13/2022]
Abstract
Induction of mammalian heme oxygenase (HO)-1 and exposure of animals to carbon monoxide (CO) ameliorates experimental colitis. When enteric bacteria, including Escherichia coli, are exposed to low iron conditions, they express an HO-like enzyme, chuS, and metabolize heme into iron, biliverdin and CO. Given the abundance of enteric bacteria residing in the intestinal lumen, our postulate was that commensal intestinal bacteria may be a significant source of CO and those that express chuS and other Ho-like molecules suppress inflammatory immune responses through release of CO. According to real-time PCR, exposure of mice to CO results in changes in enteric bacterial composition and increases E. coli 16S and chuS DNA. Moreover, the severity of experimental colitis correlates positively with E. coli chuS expression in IL-10 deficient mice. To explore functional roles, E. coli were genetically modified to overexpress chuS or the chuS gene was deleted. Co-culture of chuS-overexpressing E. coli with bone marrow-derived macrophages resulted in less IL-12p40 and greater IL-10 secretion than in wild-type or chuS-deficient E. coli. Mice infected with chuS-overexpressing E. coli have more hepatic CO and less serum IL-12 p40 than mice infected with chuS-deficient E. coli. Thus, CO alters the composition of the commensal intestinal microbiota and expands populations of E. coli that harbor the chuS gene. These bacteria are capable of attenuating innate immune responses through expression of chuS. Bacterial HO-like molecules and bacteria-derived CO may represent novel targets for therapeutic intervention in inflammatory conditions.
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Affiliation(s)
- Nitsan Maharshak
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599.,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599.,Department of Gastroenterology and Liver Diseases, Tel Aviv Medical Center, Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Hyungjin Sally Ryu
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Ting-Jia Fan
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Joseph C Onyiah
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599.,Division of Gastroenterology and Hepatology, Department of Medicine, University of Colorado, Aurora, CO and Denver VA Medical Center, Denver, Colorado, 80220
| | - Stephanie Schulz
- Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University School of Medicine, Palo Alto, California, 94305
| | - Sherrie L Otterbein
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Ron Wong
- Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University School of Medicine, Palo Alto, California, 94305
| | - Jonathan J Hansen
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599.,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Leo E Otterbein
- Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University School of Medicine, Palo Alto, California, 94305
| | - Ian M Carroll
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Scott E Plevy
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599.,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
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20
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The HC, Thanh DP, Holt KE, Thomson NR, Baker S. The genomic signatures of Shigella evolution, adaptation and geographical spread. Nat Rev Microbiol 2016; 14:235-50. [PMID: 26923111 DOI: 10.1038/nrmicro.2016.10] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Shigella spp. are some of the key pathogens responsible for the global burden of diarrhoeal disease. These facultative intracellular bacteria belong to the family Enterobacteriaceae, together with other intestinal pathogens, such as Escherichia coli and Salmonella spp. The genus Shigella comprises four different species, each consisting of several serogroups, all of which show phenotypic similarity, including invasive pathogenicity. DNA sequencing suggests that this similarity results from the convergent evolution of different Shigella spp. founders. Here, we review the evolutionary relationships between Shigella spp. and E . coli, and we highlight how the genomic plasticity of these bacteria and their acquisition of a distinctive virulence plasmid have enabled the development of such highly specialized pathogens. Furthermore, we discuss the insights that genotyping and whole-genome sequencing have provided into the phylogenetics and intercontinental spread of Shigella spp.
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Affiliation(s)
- Hao Chung The
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 764 Vo Van Kiet, Quan 5, Ho Chi Minh City, Vietnam
| | - Duy Pham Thanh
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 764 Vo Van Kiet, Quan 5, Ho Chi Minh City, Vietnam
| | - Kathryn E Holt
- Centre for Systems Genomics, University of Melbourne.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3052, Australia
| | - Nicholas R Thomson
- Bacterial Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK.,Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK
| | - Stephen Baker
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 764 Vo Van Kiet, Quan 5, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.,Department of Pathogen and Molecular Biology, The London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
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21
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Wei Y, Murphy ER. Shigella Iron Acquisition Systems and their Regulation. Front Cell Infect Microbiol 2016; 6:18. [PMID: 26904516 PMCID: PMC4746246 DOI: 10.3389/fcimb.2016.00018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/25/2016] [Indexed: 11/28/2022] Open
Abstract
Survival of Shigella within the host is strictly dependent on the ability of the pathogen to acquire essential nutrients, such as iron. As an innate immune defense against invading pathogens, the level of bio-available iron within the human host is maintained at exceeding low levels, by sequestration of the element within heme and other host iron-binding compounds. In response to sequestration mediated iron limitation, Shigella produce multiple iron-uptake systems that each function to facilitate the utilization of a specific host-associated source of nutrient iron. As a mechanism to balance the essential need for iron and the toxicity of the element when in excess, the production of bacterial iron acquisition systems is tightly regulated by a variety of molecular mechanisms. This review summarizes the current state of knowledge on the iron-uptake systems produced by Shigella species, their distribution within the genus, and the molecular mechanisms that regulate their production.
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Affiliation(s)
- Yahan Wei
- Department of Biological Sciences, Ohio University Athens, OH, USA
| | - Erin R Murphy
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University Athens, OH, USA
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22
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Fris ME, Murphy ER. Riboregulators: Fine-Tuning Virulence in Shigella. Front Cell Infect Microbiol 2016; 6:2. [PMID: 26858941 PMCID: PMC4728522 DOI: 10.3389/fcimb.2016.00002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/08/2016] [Indexed: 11/13/2022] Open
Abstract
Within the past several years, RNA-mediated regulation (ribo-regulation) has become increasingly recognized for its importance in controlling critical bacterial processes. Regulatory RNA molecules, or riboregulators, are perpetually responsive to changes within the micro-environment of a bacterium. Notably, several characterized riboregulators control virulence in pathogenic bacteria, as is the case for each riboregulator characterized to date in Shigella. The timing of virulence gene expression and the ability of the pathogen to adapt to rapidly changing environmental conditions is critical to the establishment and progression of infection by Shigella species; ribo-regulators mediate each of these important processes. This mini review will present the current state of knowledge regarding RNA-mediated regulation in Shigella by detailing the characterization and function of each identified riboregulator in these pathogens.
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Affiliation(s)
- Megan E Fris
- Department of Biological Science, Ohio University Athens, OH, USA
| | - Erin R Murphy
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University Athens, OH, USA
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23
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Ouellet YH, Ndiaye CT, Gagné SM, Sebilo A, Suits MD, Jubinville É, Jia Z, Ivancich A, Couture M. An alternative reaction for heme degradation catalyzed by the Escherichia coli O157:H7 ChuS protein: Release of hematinic acid, tripyrrole and Fe(III). J Inorg Biochem 2016; 154:103-13. [DOI: 10.1016/j.jinorgbio.2015.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 10/08/2015] [Accepted: 11/01/2015] [Indexed: 11/24/2022]
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24
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Jung LS, Ahn J. Evaluation of bacteriophage amplification assay for rapid detection of Shigella boydii in food systems. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-015-1178-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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25
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TonB-dependent heme iron acquisition in the tsetse fly symbiont Sodalis glossinidius. Appl Environ Microbiol 2015; 81:2900-9. [PMID: 25681181 DOI: 10.1128/aem.04166-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Sodalis glossinidius is an intra- and extracellular symbiont of the tsetse fly (Glossina sp.), which feeds exclusively on vertebrate blood. S. glossinidius resides in a wide variety of tsetse tissues and may encounter environments that differ dramatically in iron content. The Sodalis chromosome encodes a putative TonB-dependent outer membrane heme transporter (HemR) and a putative periplasmic/inner membrane ABC heme permease system (HemTUV). Because these gene products mediate iron acquisition processes by other enteric bacteria, we characterized their regulation and physiological role in the Sodalis/tsetse system. Our results show that the hemR and tonB genes are expressed by S. glossinidius in the tsetse fly. Furthermore, transcription of hemR in Sodalis is repressed in a high-iron environment by the iron-responsive transcriptional regulator Fur. Expression of the S. glossinidius hemR and hemTUV genes in an Escherichia coli strain unable to use heme as an iron source stimulated growth in the presence of heme or hemoglobin as the sole iron source. This stimulation was dependent on the presence of either the E. coli or Sodalis tonB gene. Sodalis tonB and hemR mutant strains were defective in their ability to colonize the gut of tsetse flies that lacked endogenous symbionts, while wild-type S. glossinidius proliferated in this same environment. Finally, we show that the Sodalis HemR protein is localized to the bacterial membrane and appears to bind hemin. Collectively, this study provides strong evidence that TonB-dependent, HemR-mediated iron acquisition is important for the maintenance of symbiont homeostasis in the tsetse fly, and it provides evidence for the expression of bacterial high-affinity iron acquisition genes in insect symbionts.
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26
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Cj1386, an atypical hemin-binding protein, mediates hemin trafficking to KatA in Campylobacter jejuni. J Bacteriol 2014; 197:1002-11. [PMID: 25548249 DOI: 10.1128/jb.02346-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Catalase enzymes detoxify H2O2 by the dismutation of H2O2 into O2 and H2O through the use of hemin cofactors. While the structure and biochemical properties of catalase enzymes have been well characterized over many decades of research, it remained unclear how catalases acquire hemin. We have previously reported that Cj1386 is essential for ensuring proper hemin content in Campylobacter jejuni catalase (KatA) (A. Flint, Y. Q. Sun, and A. Stintzi, J Bacteriol 194: 334-345, 2012). In this report, an in-depth molecular characterization of Cj1386 was performed to elucidate the mechanistic details of this association. Coimmunoprecipitation assays revealed that KatA-Cj1386 transiently interact in vivo, and UV-visible spectroscopy demonstrated that purified Cj1386 protein binds hemin. Furthermore, hemin titration experiments determined that hemin binds to Cj1386 in a 1:1 ratio with hexacoordinate hemin binding. Mutagenesis of potential hemin-coordinating residues in Cj1386 showed that tyrosine 57 was essential for hemin coordination when Cj1386 was overexpressed in Escherichia coli. The importance of tyrosine 57 in hemin trafficking in vivo was confirmed by introducing the cj1386(Y57A) allele into a C. jejuni Δcj1386 mutant background. The cj1386(Y57A) mutation resulted in increased sensitivity toward H2O2 relative to the wild type, suggesting that KatA was not functional in this strain. In support of this finding, KatA immunoprecipitated from the Δcj1386+cj1386(Y57A) mutant had significantly reduced hemin content compared to that of the cj1386(WT) background. Overall, these findings indicate that Cj1386 is involved in directly trafficking hemin to KatA and that tyrosine 57 plays a key role in this function.
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27
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Krajewski SS, Narberhaus F. Temperature-driven differential gene expression by RNA thermosensors. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:978-988. [PMID: 24657524 DOI: 10.1016/j.bbagrm.2014.03.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/28/2014] [Accepted: 03/14/2014] [Indexed: 12/20/2022]
Abstract
Many prokaryotic genes are organized in operons. Genes organized in such transcription units are co-transcribed into a polycistronic mRNA. Despite being clustered in a single mRNA, individual genes can be subjected to differential regulation, which is mainly achieved at the level of translation depending on initiation and elongation. Efficiency of translation initiation is primarily determined by the structural accessibility of the ribosome binding site (RBS). Structured cis-regulatory elements like RNA thermometers (RNATs) can contribute to differential regulation of individual genes within a polycistronic mRNA. RNATs are riboregulators that mediate temperature-responsive regulation of a downstream gene by modulating the accessibility of its RBS. At low temperature, the RBS is trapped by intra-molecular base pairing prohibiting translation initiation. The secondary structure melts with increasing temperature thus liberating the RBS. Here, we present an overview of different RNAT types and specifically highlight recently discovered RNATs. The main focus of this review is on RNAT-based differential control of polycistronic operons. Finally, we discuss the influence of temperature on other riboregulators and the potential of RNATs in synthetic RNA biology. This article is part of a Special Issue entitled: Riboswitches.
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28
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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: 81] [Impact Index Per Article: 7.4] [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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RNA-mediated thermoregulation of iron-acquisition genes in Shigella dysenteriae and pathogenic Escherichia coli. PLoS One 2013; 8:e63781. [PMID: 23704938 PMCID: PMC3660397 DOI: 10.1371/journal.pone.0063781] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/07/2013] [Indexed: 12/29/2022] Open
Abstract
The initiation, progression and transmission of most bacterial infections is dependent upon the ability of the invading pathogen to acquire iron from each of the varied environments encountered during the course of a natural infection. In total, 95% of iron within the human body is complexed within heme, making heme a potentially rich source of host-associated nutrient iron for invading bacteria. As heme is encountered only within the host, pathogenic bacteria often regulate synthesis of heme utilization factors such that production is maximal under host-associated environmental conditions. This study examines the regulated production of ShuA, an outer-membrane receptor required for the utilization of heme as a source of nutrient iron by Shigella dysenteriae, a pathogenic bacterium that causes severe diarrheal diseases in humans. Specifically, the impact of the distinct environmental temperatures encountered during infection within a host (37°C) and transmission between hosts (25°C) on shuA expression is investigated. We show that shuA expression is subject to temperature-dependent post-transcriptional regulation resulting in increased ShuA production at 37°C. The observed thermoregulation is mediated by nucleic acid sequences within the 5' untranslated region. In addition, we have identified similar nucleotide sequences within the 5' untranslated region of the orthologous chuA transcript of enteropathogenic E. coli and have demonstrated that it also functions to confer temperature-dependent post-transcriptional regulation. In both function and predicted structure, the regulatory element within the shuA and chuA 5' untranslated regions closely resembles a FourU RNA thermometer, a zipper-like RNA structure that occludes the Shine-Dalgarno sequence at low temperatures. Increased production of ShuA and ChuA in response to the host body temperature allows for maximal production of these heme acquisition factors within the environment where S. dysenteriae and pathogenic E. coli strains would encounter heme, a host-specific iron source.
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Abstract
The transcription factor Fur regulates the expression of a number of genes in Vibrio cholerae in response to changes in the level of available iron. Fur usually acts as a repressor, but here we show that Fur positively regulates the expression of ompT, which encodes a major outer membrane porin. OmpT levels increased when the bacteria were grown in medium containing relatively high levels of iron, and this effect required Fur. The level of ompT mRNA also is increased in the presence of iron and Fur. The effect of iron on OmpT levels was independent of the known ompT regulators ToxR and Crp, and it did not require RyhB, which has been shown to be responsible for positive regulation by iron of some V. cholerae genes. Electrophoretic mobility shift assays showed that Fur binds upstream of the ompT transcription start site in a region overlapping known binding sites for ToxR and Crp. These data suggest that Fur and iron positively regulate ompT expression through the direct binding of Fur to the ompT promoter.
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Bosilevac JM, Koohmaraie M. Prevalence and characterization of non-O157 shiga toxin-producing Escherichia coli isolates from commercial ground beef in the United States. Appl Environ Microbiol 2011; 77:2103-12. [PMID: 21257806 PMCID: PMC3067332 DOI: 10.1128/aem.02833-10] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O157:H7 is a Shiga toxin (stx)-producing E. coli (STEC) strain that has been classified as an adulterant in U.S. beef. However, numerous other non-O157 STEC strains are associated with diseases of various severities and have become an increasing concern to the beef industry, regulatory officials, and the public. This study reports on the prevalence and characterization of non-O157 STEC in commercial ground beef samples (n = 4,133) obtained from numerous manufacturers across the United States over a period of 24 months. All samples were screened by DNA amplification for the presence of Shiga toxin genes, which were present in 1,006 (24.3%) of the samples. Then, culture isolation of an STEC isolate from all samples that contained stx(1) and/or stx(2) was attempted. Of the 1,006 positive ground beef samples screened for stx, 300 (7.3% of the total of 4,133) were confirmed to have at least one strain of STEC present by culture isolation. In total, 338 unique STEC isolates were recovered from the 300 samples that yielded an STEC isolate. All unique STEC isolates were serotyped and were characterized for the presence of known virulence factors. These included Shiga toxin subtypes, intimin subtypes, and accessory virulence factors related to adherence (saa, iha, lifA), toxicity (cnf, subA, astA), iron acquisition (chuA), and the presence of the large 60-MDa virulence plasmid (espP, etpD, toxB, katP, toxB). The isolates were also characterized by use of a pathogenicity molecular risk assessment (MRA; based on the presence of various O-island nle genes). Results of this characterization identified 10 STEC isolates (0.24% of the 4,133 total) that may be considered a significant food safety threat, defined by the presence of eae, subA, and nle genes.
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Affiliation(s)
- Joseph M Bosilevac
- USDA, ARS, U.S. Meat Animal Research Center, P.O. Box 166, State Spur 18D, Clay Center, NE 68933-0166, USA.
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Regulation of high-affinity iron acquisition homologues in the tsetse fly symbiont Sodalis glossinidius. J Bacteriol 2010; 192:3780-7. [PMID: 20494987 DOI: 10.1128/jb.00161-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sodalis glossinidius is a facultative intracellular bacterium that is a secondary symbiont of the tsetse fly (Diptera: Glossinidae). Since studies with other facultative intracellular bacteria have shown that high-affinity iron acquisition genes are upregulated in vivo, we investigated the regulation of several Sodalis genes that encode putative iron acquisition systems. These genes, SG1538 (hemT) and SG1516 (sitA), are homologous to genes encoding periplasmic heme and iron/manganese transporters, respectively. hemT promoter- and sitA promoter-gfp fusions were constructed, and in both Escherichia coli and Sodalis backgrounds, expression levels of these fusions were higher when the bacteria were grown in iron-limiting media than when the bacteria were grown in iron-replete media. The Sodalis promoters were tested for iron regulation in an E. coli strain that lacks the fur gene, which encodes the iron-responsive transcriptional repressor Fur. Expression of the promoter-gfp fusions in the E. coli fur mutant was constitutively high in both iron-replete and iron-deplete media, and addition of either Shigella flexneri fur or Sodalis fur to a plasmid restored normal regulation. A Sodalis fur mutant was constructed by intron mutagenesis, and semiquantitative reverse transcription-PCR (RT-PCR) showed that iron repression of sitA expression was also abolished in this strain. In vivo expression analysis showed that hemT and sitA are expressed when Sodalis is within tsetse fly hosts, suggesting a biological role for these genes when Sodalis is within the tsetse fly.
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Lewis JP. Metal uptake in host-pathogen interactions: role of iron in Porphyromonas gingivalis interactions with host organisms. Periodontol 2000 2010; 52:94-116. [PMID: 20017798 DOI: 10.1111/j.1600-0757.2009.00329.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Cobessi D, Meksem A, Brillet K. Structure of the heme/hemoglobin outer membrane receptor ShuA fromShigella dysenteriae: Heme binding by an induced fit mechanism. Proteins 2010; 78:286-94. [DOI: 10.1002/prot.22539] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Suits MDL, Lang J, Pal GP, Couture M, Jia Z. Structure and heme binding properties of Escherichia coli O157:H7 ChuX. Protein Sci 2009; 18:825-38. [PMID: 19319934 PMCID: PMC2762594 DOI: 10.1002/pro.84] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
For many pathogenic microorganisms, iron acquisition from host heme sources stimulates growth, multiplication, ultimately enabling successful survival and colonization. In gram-negative Escherichia coli O157:H7, Shigella dysenteriae and Yersinia enterocolitica the genes encoded within the heme utilization operon enable the effective uptake and utilization of heme as an iron source. While the complement of proteins responsible for heme internalization has been determined in these organisms, the fate of heme once it has reached the cytoplasm has only recently begun to be resolved. Here we report the first crystal structure of ChuX, a member of the conserved heme utilization operon from pathogenic E. coli O157:H7 determined at 2.05 A resolution. ChuX forms a dimer which remarkably given low sequence homology, displays a very similar fold to the monomer structure of ChuS and HemS, two other heme utilization proteins. Absorption spectral analysis of heme reconstituted ChuX demonstrates that ChuX binds heme in a 1:1 manner implying that each ChuX homodimer has the potential to coordinate two heme molecules in contrast to ChuS and HemS where only one heme molecule is bound. Resonance Raman spectroscopy indicates that the heme of ferric ChuX is composed of a mixture of coordination states: 5-coordinate and high-spin, 6-coordinate and low-spin, and 6-coordinate and high-spin. In contrast, the reduced ferrous form displays mainly a 5-coordinate and high-spin state with a minor contribution from a 6-coordinate and low-spin state. The nu(Fe-CO) and nu(C-O) frequencies of ChuX-bound CO fall on the correlation line expected for histidine-coordinated hemoproteins indicating that the fifth axial ligand of the ferrous heme is the imidazole ring of a histidine residue. Based on sequence and structural comparisons, we designed a number of site-directed mutations in ChuX to probe the heme binding sites and dimer interface. Spectral analysis of ChuX and mutants suggests involvement of H65 and H98 in heme coordination as mutations of both residues were required to abolish the formation of the hexacoordination state of heme-bound ChuX.
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Affiliation(s)
- Michael D L Suits
- Department of Biochemistry, Queen's UniversityKingston, Ontario, Canada K7L 3N6
| | - Jérôme Lang
- Département de Biochimie et de Microbiologie, Université LavalQuebec City, Quebec, Canada G1K 7P4
| | - Gour P Pal
- Department of Biochemistry, Queen's UniversityKingston, Ontario, Canada K7L 3N6
| | - Manon Couture
- Département de Biochimie et de Microbiologie, Université LavalQuebec City, Quebec, Canada G1K 7P4
| | - Zongchao Jia
- Department of Biochemistry, Queen's UniversityKingston, Ontario, Canada K7L 3N6,*Correspondence to: Zongchao Jia, Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6. E-mail:
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Genetics and virulence association of the Shigella flexneri sit iron transport system. Infect Immun 2009; 77:1992-9. [PMID: 19289511 DOI: 10.1128/iai.00064-09] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The sit-encoded iron transport system is present within pathogenicity islands in all Shigella spp. and some pathogenic Escherichia coli strains. The islands contain numerous insertion elements and sequences with homology to bacteriophage genes. The Shigella flexneri sit genes can be lost as a result of deletion within the island. The formation of deletions was dependent upon RecA and occurred at relatively high frequency. This suggests that the sit region is inherently unstable, yet sit genes are maintained in all of the clinical isolates tested. Characterization of the sitABCD genes in S. flexneri indicates that they encode a ferrous iron transport system, although the genes are induced aerobically. The sit genes provide a competitive advantage to S. flexneri growing within epithelial cells, and a sitA mutant is outcompeted by the wild type in cultured epithelial cells. The Sit system is also required for virulence in a mouse lung model. The sitA mutant was able to infect the mice and induce a protective immune response but was avirulent compared to its wild-type parent strain.
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Genetics and environmental regulation of Shigella iron transport systems. Biometals 2009; 22:43-51. [PMID: 19130265 DOI: 10.1007/s10534-008-9188-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 12/07/2008] [Indexed: 10/21/2022]
Abstract
Shigella spp. have transport systems for both ferric and ferrous iron. The iron can be taken up as free iron or complexed to a variety of carriers. All Shigella species have both the Feo and Sit systems for acquisition of ferrous iron, and all have at least one siderophore-mediated system for transport of ferric iron. Several of the transport systems, including Sit, Iuc/IutA (aerobactin synthesis and transport), Fec (ferric di-citrate uptake), and Shu (heme transport) are encoded within pathogenicity islands. The presence and the genomic locations of these islands vary considerably among the Shigella species, and even between isolates of the same species. The expression of the iron transport systems is influenced by the concentration of iron and by environmental conditions including the level of oxygen. ArcA and FNR regulate iron transport gene expression as a function of oxygen tension, with the sit and iuc promoters being highly expressed in aerobic conditions, while the feo ferrous iron transporter promoter is most active under anaerobic conditions. The effects of oxygen are also seen in infection of cultured cells by Shigella flexneri; the Sit and Iuc systems support plaque formation under aerobic conditions, whereas Feo allows plaque formation anaerobically.
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Sobieszczańska B. Distribution of genes encoding iron uptake systems among enteroaggregative Escherichia coli strains isolated from adults with irritable bowel syndrome. Clin Microbiol Infect 2008; 14:1083-6. [DOI: 10.1111/j.1469-0691.2008.02093.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hagan EC, Mobley HLT. Haem acquisition is facilitated by a novel receptor Hma and required by uropathogenic Escherichia coli for kidney infection. Mol Microbiol 2008; 71:79-91. [PMID: 19019144 DOI: 10.1111/j.1365-2958.2008.06509.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron acquisition, mediated by specific outer membrane receptors, is critical for colonization of the urinary tract by uropathogenic Escherichia coli (UPEC). The role of specific iron sources in vivo, however, remains largely unknown. In this study, we identified a 79 kDa haem receptor, haemacquisition protein Hma, and established that it functions independently of ChuA to mediate haemin uptake by UPEC strain CFT073. We demonstrated that expression of hma promotes TonB-dependent haemin utilization and the Hma protein binds haemin with high affinity (K(d) = 8 microM). Hma, however, lacks conserved His residues shown to mediate haem uptake by other bacterial receptors. In contrast, we identified Tyr-126 as a residue necessary for Hma-mediated haemin utilization. In a murine co-infection model of UTI, an isogenic hma mutant was out-competed by wild-type CFT073 in the kidneys (P < 0.001) and spleens (P < 0.0001) of infected mice, indicating its expression provided a competitive advantage in these organs. Furthermore, a hma chuA double mutant, which is unable to utilize haemin, was unable to colonize the kidneys to wild-type levels during independent infection (P = 0.02). Thus, we demonstrate that UPEC requires haem for kidney colonization and that uptake of this iron source is mediated, in part, by the novel receptor, Hma.
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Affiliation(s)
- Erin C Hagan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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40
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Tong Y, Guo M. Bacterial heme-transport proteins and their heme-coordination modes. Arch Biochem Biophys 2008; 481:1-15. [PMID: 18977196 DOI: 10.1016/j.abb.2008.10.013] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 10/07/2008] [Accepted: 10/07/2008] [Indexed: 12/11/2022]
Abstract
Efficient iron acquisition is critical for an invading microbe's survival and virulence. Most of the iron in mammals is incorporated into heme, which can be plundered by certain bacterial pathogens as a nutritional iron source. Utilization of exogenous heme by bacteria involves the binding of heme or hemoproteins to the cell surface receptors, followed by the transport of heme into cells. Once taken into the cytosol, heme is presented to heme oxygenases where the tetrapyrrole ring is cleaved in order to release the iron. Some Gram-negative bacteria also secrete extracellular heme-binding proteins called hemophores, which function to sequester heme from the environment. The heme-transport genes are often genetically linked as gene clusters under Fur (ferric uptake regulator) regulation. This review discusses the gene clusters and proteins involved in bacterial heme acquisition, transport and processing processes, with special focus on the heme-coordination, protein structures and mechanisms underlying heme-transport.
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Affiliation(s)
- Yong Tong
- Department of Chemistry and Biochemistry, University of Massachusetts, 285 Old Westport Road, Dartmouth, MA 02747-2300, USA
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Cavallaro G, Decaria L, Rosato A. Genome-Based Analysis of Heme Biosynthesis and Uptake in Prokaryotic Systems. J Proteome Res 2008; 7:4946-54. [DOI: 10.1021/pr8004309] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriele Cavallaro
- Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Leonardo Decaria
- Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Antonio Rosato
- Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
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Nairz M, Fritsche G, Brunner P, Talasz H, Hantke K, Weiss G. Interferon-gamma limits the availability of iron for intramacrophage Salmonella typhimurium. Eur J Immunol 2008; 38:1923-36. [PMID: 18581323 DOI: 10.1002/eji.200738056] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In stimulating effector functions of mononuclear phagocytes, IFN-gamma is of pivotal importance in host defense against intramacrophage pathogens including salmonellae. As the activity of IFN-gamma is modulated by iron and since a sufficient availability of iron is essential for the growth of pathogens, we investigated the regulatory effects of IFN-gamma on iron homeostasis and immune function in murine macrophages infected with Salmonella typhimurium. In Salmonella-infected phagocytes, IFN-gamma caused a significant reduction of iron uptake via transferrin receptor 1 and resulted in an increased iron efflux caused by an enhanced expression of the iron exporter ferroportin 1. Moreover, the expression of haem oxygenase 1 and of the siderophore-capturing antimicrobial peptide lipocalin 2 was markedly elevated following bacterial invasion, with IFN-gamma exerting a super-inducing effect. This observed regulatory impact of IFN-gamma reduced the intracellular iron pools within infected phagocytes, thus restricting the acquisition of iron by engulfed Salmonella typhimurium while concomitantly promoting NO and TNF-alpha production. Our data suggest that the modulation of crucial pathways of macrophage iron metabolism in response to IFN-gamma concordantly aims at withdrawing iron from intracellular Salmonella and at strengthening macrophage immune response functions. These regulations are thus consistent with the principles of nutritional immunity.
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Affiliation(s)
- Manfred Nairz
- Department of General Internal Medicine, Clinical Immunology and Infectious Diseases, Medical University Innsbruck, Anichstrasse 35, Innsbruck, Austria
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Escherichia coli O157:H7 survives within human macrophages: global gene expression profile and involvement of the Shiga toxins. Infect Immun 2008; 76:4814-22. [PMID: 18725421 DOI: 10.1128/iai.00446-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O157:H7 is an important food-borne pathogen that specifically binds to the follicle-associated epithelium in the intestine, which rapidly brings this bacterial pathogen in contact with underlying human macrophages. Very little information is available about the interaction between E. coli O157:H7 and human macrophages. We evaluated the uptake and survival of strain EDL933 during infection of human macrophages. Surprisingly, EDL933 survived and multiplied in human macrophages at 24 h postinfection. The global gene expression profile of this pathogen during macrophage infection was determined. Inside human macrophages, upregulation of E. coli O157:H7 genes carried on O islands (such as pagC, the genes for both of the Shiga toxins, and the two iron transport system operons fit and chu) was observed. Genes involved in acid resistance and in the SOS response were upregulated. However, genes of the locus of enterocyte effacement or genes involved in peroxide resistance were not differentially expressed. Many genes with putative or unknown functions were upregulated inside human macrophages and may be newly discovered virulence factors. As the Shiga toxin genes were upregulated in macrophages, survival and cytotoxicity assays were performed with isogenic Shiga toxin mutants. The initial uptake of Shiga toxins mutants was higher than that of the wild type; however, the survival rates were significantly lower at 24 h postinfection. Thus, Shiga toxins are implicated in the interaction between E. coli O157:H7 and human macrophages. Understanding the molecular mechanisms used by E. coli to survive within macrophages may help in the identification of targets for new therapeutic agents.
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Long KZ, Rosado JL, Fawzi W. The Comparative Impact of Iron, the B-Complex Vitamins, Vitamins C and E, and Selenium on Diarrheal Pathogen Outcomes Relative to the Impact Produced by Vitamin A and Zinc. Nutr Rev 2008; 65:218-32. [PMID: 17566548 DOI: 10.1111/j.1753-4887.2007.tb00299.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Micronutrient supplementation offers one of the most cost-effective means of improving the health and survival of children in developing countries. However, the effects of supplementation with single micronutrients on diarrhea are not always consistent, and supplementation with multi-micronutrient supplements can have negative effects. These inconsistencies may result from the failure to consider the diverse etiological agents that cause diarrhea and the unique effects each micronutrient has on the immune response to each of these agents. This review examines the separate effects that supplementation with the B-complex vitamins, vitamin C, vitamin E, selenium, and iron have on diarrheal disease-related outcomes. Supplementation with iron may increase the risk of infection by invasive diarrheal pathogens, while supplementation with the remaining micronutrients may reduce this risk. These differences may be due to distinct regulatory effects each micronutrient has on the pathogen-specific immune response, as well as on the virulence of specific pathogens. The findings of these studies suggest that micronutrient supplementation of children must take into account the pathogens prevalent within communities as reflected by their diarrheal disease burdens. The effectiveness of combining multiple micronutrients into one supplement must also be reconsidered.
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Affiliation(s)
- Kurt Z Long
- Harvard School of Public Health, Department of Nutrition, Harvard School of Public Health, 1663 Tremont Street, Boston, MA 02115, USA.
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Abstract
Vibrio cholerae uses a variety of strategies for obtaining iron in its diverse environments. In this study we report the identification of a novel iron utilization protein in V. cholerae, VciB. The vciB gene and its linked gene, vciA, were isolated in a screen for V. cholerae genes that permitted growth of an Escherichia coli siderophore mutant in low-iron medium. The vciAB operon encodes a predicted TonB-dependent outer membrane receptor, VciA, and a putative inner membrane protein, VciB. VciB, but not VciA, was required for growth stimulation of E. coli and Shigella flexneri strains in low-iron medium. Consistent with these findings, TonB was not needed for VciB-mediated growth. No growth enhancement was seen when vciB was expressed in an E. coli or S. flexneri strain defective for the ferrous iron transporter Feo. Supplying the E. coli feo mutant with a plasmid encoding either E. coli or V. cholerae Feo, or the S. flexneri ferrous iron transport system Sit, restored VciB-mediated growth; however, no stimulation was seen when either of the ferric uptake systems V. cholerae Fbp and Haemophilus influenzae Hit was expressed. These data indicate that VciB functions by promoting iron uptake via a ferrous, but not ferric, iron transport system. VciB-dependent iron accumulation via Feo was demonstrated directly in iron transport assays using radiolabeled iron. A V. cholerae vciB mutant did not exhibit any growth defects in either in vitro or in vivo assays, possibly due to the presence of other systems with overlapping functions in this pathogen.
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46
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Functional differences between heme permeases: Serratia marcescens HemTUV permease exhibits a narrower substrate specificity (restricted to heme) than the Escherichia coli DppABCDF peptide-heme permease. J Bacteriol 2008; 190:1866-70. [PMID: 18178744 DOI: 10.1128/jb.01636-07] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serratia marcescens hemTUV genes encoding a potential heme permease were cloned in Escherichia coli recombinant mutant FB827 dppF::Km(pAM 238-hasR). This strain, which expresses HasR, a foreign heme outer membrane receptor, is potentially capable of using heme as an iron source. However, this process is invalidated due to a dppF::Km mutation which inactivates the Dpp heme/peptide permease responsible for heme, dipeptide, and delta-aminolevulinic (ALA) transport through the E. coli inner membrane. We show here that hemTUV genes complement the Dpp permease for heme utilization as an iron source and thus are functional in E. coli. However, hemTUV genes do not complement the Dpp permease for ALA uptake, indicating that the HemTUV permease does not transport ALA. Peptides do not inhibit heme uptake in vivo, indicating that, unlike Dpp permease, HemTUV permease does not transport peptides. HemT, the periplasmic binding protein, binds heme. Heme binding is saturable and not inhibited by peptides that inhibit heme uptake by the Dpp system. Thus, the S. marcescens HemTUV permease and, most likely, HemTUV orthologs present in many gram-negative pathogens form a class of heme-specific permeases different from the Dpp peptide/heme permease characterized in E. coli.
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Paulley JT, Anderson ES, Roop RM. Brucella abortus requires the heme transporter BhuA for maintenance of chronic infection in BALB/c mice. Infect Immun 2007; 75:5248-54. [PMID: 17709407 PMCID: PMC2168305 DOI: 10.1128/iai.00460-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The gene annotated BAB2_1150 in the Brucella abortus 2308 genome sequence is predicted to encode a homolog of the well-characterized heme transporter ShuA of Shigella dysenteriae and accordingly has been given the designation bhuA (Brucella heme utilization). Phenotypic analysis of an isogenic bhuA mutant derived from B. abortus 2308 verified that there is a link between BhuA and the ability of the parent strain to use heme as an iron source in in vitro assays. Maximum expression of bhuA in B. abortus 2308 is observed during stationary phase when this strain in cultivated in low-iron minimal medium, and a comparison of the growth characteristics of the B. abortus bhuA mutant and 2308 in this medium suggested that heme serves as an important iron source for the parent strain during stationary phase. The B. abortus bhuA mutant HR1703 exhibits significant attenuation in cultured murine macrophages compared to strain 2308, and unlike its parent strain, the B. abortus bhuA mutant is unable to maintain a chronic spleen infection in experimentally infected BALB/c mice. These experimental findings suggest that heme and/or heme-containing proteins represent important iron sources for B. abortus 2308 during its residence in the mammalian host and that BhuA is required for efficient utilization of these iron sources.
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Affiliation(s)
- James T Paulley
- Department of Microbiology and Immunology, East Carolina University School of Medicine, 600 Moye Boulevard, Greenville, NC 27834, USA
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Matte A, Jia Z, Sunita S, Sivaraman J, Cygler M. Insights into the biology of Escherichia coli through structural proteomics. ACTA ACUST UNITED AC 2007; 8:45-55. [PMID: 17668295 DOI: 10.1007/s10969-007-9019-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 06/28/2007] [Indexed: 10/23/2022]
Abstract
Escherichia coli has historically been an important organism for understanding a multitude of biological processes, and represents a model system as we attempt to simulate the workings of living cells. Many E. coli strains are also important human and animal pathogens for which new therapeutic strategies are required. For both reasons, a more complete and comprehensive understanding of the protein structure complement of E. coli is needed at the genome level. Here, we provide examples of insights into the mechanism and function of bacterial proteins that we have gained through the Bacterial Structural Genomics Initiative (BSGI), focused on medium-throughput structure determination of proteins from E. coli. We describe the structural characterization of several enzymes from the histidine biosynthetic pathway, the structures of three pseudouridine synthases, enzymes that synthesize one of the most abundant modified bases in RNA, as well as the combined use of protein structure and focused functional analysis to decipher functions for hypothetical proteins. Together, these results illustrate the power of structural genomics to contribute to a deeper biological understanding of bacterial processes.
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Affiliation(s)
- Allan Matte
- Biotechnology Research Institute, National Research Council Canada, Montreal, QC, Canada.
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Adams MA, Suits MDL, Zheng J, Jia Z. Piecing together the structure–function puzzle: Experiences in structure-based functional annotation of hypothetical proteins. Proteomics 2007; 7:2920-32. [PMID: 17639604 DOI: 10.1002/pmic.200700099] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The combination of genomic sequencing with structural genomics has provided a wealth of new structures for previously uncharacterized ORFs, more commonly referred to as hypothetical proteins. This rapid growth has been the direct result of high-throughput, automated approaches in both the identification of new ORFs and the determination of high-resolution 3-D protein structures. A significant bottleneck is reached, however, at the stage of functional annotation in that the assignment of function is not readily automatable. It is often the case that the initial structural analysis at best indicates a functional family for a given hypothetical protein, but further identification of a relevant ligand or substrate is impeded by the diversity of function in a particular structural classification of proteins family, a highly selective and specific ligand-binding site, or the identification of a novel protein fold. Our approach to the functional annotation of hypothetical proteins relies on the combination of structural information with additional bioinformatics evidence garnered from operon prediction, loose functional information of additional operon members, conservation of catalytic residues, as well as cocrystallization trials and virtual ligand screening. The synthesis of all available information for each protein has permitted the functional annotation of several hypothetical proteins from Escherichia coli and each assignment has been confirmed through generally accepted biochemical methods.
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Affiliation(s)
- Melanie A Adams
- Department of Biochemistry, Queen's University, Kingston, ON, Canada
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Boulette ML, Payne SM. Anaerobic regulation of Shigella flexneri virulence: ArcA regulates Fur and iron acquisition genes. J Bacteriol 2007; 189:6957-67. [PMID: 17660284 PMCID: PMC2045222 DOI: 10.1128/jb.00621-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Invasion and plaque formation in epithelial monolayers are routinely used to assess the virulence of Shigella flexneri, a causative agent of dysentery. A modified plaque assay was developed to identify factors contributing to the virulence of S. flexneri under the anaerobic conditions present in the colon. This assay demonstrated the importance of the ferrous iron transport system Feo, as well as the global transcription factors Fur, ArcA, and Fnr, for Shigella plaque formation in anoxic environments. Transcriptional analyses of S. flexneri iron transport genes indicated that anaerobic conditions activated feoABC while repressing genes encoding two other iron transport systems, the ABC transporter Sit and the Iuc/Iut aerobactin siderophore synthesis and transport system. The anaerobic transcription factors ArcA and Fnr activated expression of feoABC, while ArcA repressed iucABCD iutA. Transcription of fur, encoding the iron-responsive transcriptional repressor of bacterial iron acquisition, was also repressed anaerobically in an ArcA-dependent manner.
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