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Khare G, Nangpal P, Tyagi AK. Differential Roles of Iron Storage Proteins in Maintaining the Iron Homeostasis in Mycobacterium tuberculosis. PLoS One 2017; 12:e0169545. [PMID: 28060867 PMCID: PMC5218490 DOI: 10.1371/journal.pone.0169545] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 12/19/2016] [Indexed: 02/01/2023] Open
Abstract
Ferritins and bacterioferritins are iron storage proteins that represent key players in iron homeostasis. Several organisms possess both forms of ferritins, however, their relative physiological roles are less understood. Mycobacterium tuberculosis possesses both ferritin (BfrB) and bacterioferritin (BfrA), playing an essential role in its pathogenesis as reported by us earlier. This study provides insights into the role of these two proteins in iron homeostasis by employing M. tuberculosis bfr mutants. Our data suggests that BfrA is required for efficient utilization of stored iron under low iron conditions while BfrB plays a crucial role as the major defense protein under excessive iron conditions. We show that these two proteins provide protection against oxidative stress and hypoxia. Iron incorporation study showed that BfrB has higher capacity for storing iron than BfrA, which augurs well for efficient iron quenching under iron excess conditions. Moreover, iron release assay demonstrated that BfrA has 3 times superior ability to release stored iron emphasizing its requirement for efficient iron release under low iron conditions, facilitated by the presence of heme. Thus, for the first time, our observations suggest that the importance of BfrA or BfrB separately might vary depending upon the iron situation faced by the cell.
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Affiliation(s)
- Garima Khare
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi, India
| | - Prachi Nangpal
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi, India
| | - Anil K. Tyagi
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi, India
- Vice Chancellor, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka New Delhi, India
- * E-mail:
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52
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Bradley JM, Svistunenko DA, Moore GR, Le Brun NE. Tyr25, Tyr58 and Trp133 ofEscherichia colibacterioferritin transfer electrons between iron in the central cavity and the ferroxidase centre. Metallomics 2017; 9:1421-1428. [DOI: 10.1039/c7mt00187h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tyr58 and Trp133 play key roles in the formation and decay of the Tyr25 radical species ofE. coliBFR.
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Affiliation(s)
- Justin M. Bradley
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | | | - Geoffrey R. Moore
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
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Eid R, Arab NTT, Greenwood MT. Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:399-430. [PMID: 27939167 DOI: 10.1016/j.bbamcr.2016.12.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/08/2016] [Accepted: 12/04/2016] [Indexed: 12/11/2022]
Abstract
Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe2+) and ferric (Fe3+) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.
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Affiliation(s)
- Rawan Eid
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Nagla T T Arab
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Michael T Greenwood
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada.
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Potentiation of hydrogen peroxide toxicity: From catalase inhibition to stable DNA-iron complexes. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2016; 773:274-281. [PMID: 28927535 DOI: 10.1016/j.mrrev.2016.08.006] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 08/29/2016] [Indexed: 12/15/2022]
Abstract
Hydrogen peroxide (H2O2) is unique among general toxins, because it is stable in abiotic environments at ambient temperature and neutral pH, yet rapidly kills any type of cells by producing highly-reactive hydroxyl radicals. This life-specific reactivity follows the distribution of soluble iron, Fe(II) (which combines with H2O2 to form the famous Fenton's reagent),Fe(II) is concentrated inside cells, but is virtually absent outside them. Because of the immediate danger of H2O2, all cells have powerful H2O2 scavengers, the equally famous catalases, which enable cells to survive thousand-fold higher concentrations of H2O2 and, in combination with adequate movement of H2O2 across membranes, make the killing H2O2 concentrations virtually impractical to generate in vivo. And yet, low concentrations of H2O2 are somehow used as an efficient biological weapon. Here we review several examples of how cells potentiate H2O2 toxicity with other chemicals. At first, these potentiators were thought to simply inhibit catalases, but recent findings with cyanide suggest that potentiators mostly promote the other side of Fenton's reaction, recruiting iron from cell depots into stable DNA-iron complexes that, in the presence of elevated H2O2, efficiently break duplex DNA, pulverizing the chromosome. This multifaceted potentiation of H2O2 toxicity results in robust and efficient killing.
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Meneely KM, Sundlov JA, Gulick AM, Moran GR, Lamb AL. An Open and Shut Case: The Interaction of Magnesium with MST Enzymes. J Am Chem Soc 2016; 138:9277-93. [PMID: 27373320 PMCID: PMC5029964 DOI: 10.1021/jacs.6b05134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
The shikimate pathway of bacteria,
fungi, and plants generates
chorismate, which is drawn into biosynthetic pathways that form aromatic
amino acids and other important metabolites, including folates, menaquinone,
and siderophores. Many of the pathways initiated at this branch point
transform chorismate using an MST enzyme. The MST enzymes (menaquinone, siderophore, and tryptophan biosynthetic enzymes) are structurally homologous and magnesium-dependent,
and all perform similar chemical permutations to chorismate by nucleophilic
addition (hydroxyl or amine) at the 2-position of the ring, inducing
displacement of the 4-hydroxyl. The isomerase enzymes release isochorismate
or aminodeoxychorismate as the product, while the synthase enzymes
also have lyase activity that displaces pyruvate to form either salicylate
or anthranilate. This has led to the hypothesis that the isomerase
and lyase activities performed by the MST enzymes are functionally
conserved. Here we have developed tailored pre-steady-state approaches
to establish the kinetic mechanisms of the isochorismate and salicylate
synthase enzymes of siderophore biosynthesis. Our data are centered
on the role of magnesium ions, which inhibit the isochorismate synthase
enzymes but not the salicylate synthase enzymes. Prior structural
data have suggested that binding of the metal ion occludes access
or egress of substrates. Our kinetic data indicate that for the production
of isochorismate, a high magnesium ion concentration suppresses the
rate of release of product, accounting for the observed inhibition
and establishing the basis of the ordered-addition kinetic mechanism.
Moreover, we show that isochorismate is channeled through the synthase
reaction as an intermediate that is retained in the active site by
the magnesium ion. Indeed, the lyase-active enzyme has 3 orders of
magnitude higher affinity for the isochorismate complex relative to
the chorismate complex. Apparent negative-feedback inhibition by ferrous
ions is documented at nanomolar concentrations, which is a potentially
physiologically relevant mode of regulation for siderophore biosynthesis
in vivo.
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Affiliation(s)
- Kathleen M Meneely
- Department of Molecular Biosciences, University of Kansas , Lawrence, Kansas 66045, United States
| | - Jesse A Sundlov
- Hauptman-Woodward Medical Research Institute , 700 Ellicott Street, Buffalo, New York 14203, United States
| | - Andrew M Gulick
- Hauptman-Woodward Medical Research Institute , 700 Ellicott Street, Buffalo, New York 14203, United States
| | - Graham R Moran
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Audrey L Lamb
- Department of Molecular Biosciences, University of Kansas , Lawrence, Kansas 66045, United States
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Synthetic Lethality of the bfr and mbfA Genes Reveals a Functional Relationship between Iron Storage and Iron Export in Managing Stress Responses in Bradyrhizobium japonicum. PLoS One 2016; 11:e0157250. [PMID: 27285822 PMCID: PMC4902296 DOI: 10.1371/journal.pone.0157250] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 05/26/2016] [Indexed: 11/19/2022] Open
Abstract
An mbfA mutant of Bradyrhizobium japonicum defective in iron export is sensitive to short term exposure to high levels iron or H2O2. Here, we found that the mbfA strain grown in elevated iron media (100 μM) became resistant to those treatments, suggesting a stress response adaptation. The bfr gene encodes the iron storage protein bacterioferritin, and its expression is derepressed by iron. An mbfA bfr double mutant showed a loss of stress adaptation, and had a severe growth phenotype in high iron media. Moreover, a bfrup allele in which bfr is constitutively derepressed conferred stress tolerance on an mbfA mutant without elevating the iron content in the growth media. The intracellular iron content of the mbfA bfr double mutant was substantially higher than that found in the wild type, even when grown in relatively low iron media (5 μM). Under that condition, iron-responsive gene expression was aberrant in the mbfA bfr strain. Moreover, the double mutant was sensitive to the iron-activated antibiotic streptonigrin. We conclude that MbfA and Bfr work in concert to manage iron and oxidative stresses. In addition, the need for iron detoxification is not limited to extreme environments, but is also required for normal cellular function.
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Krzyżanowska DM, Ossowicki A, Rajewska M, Maciąg T, Jabłońska M, Obuchowski M, Heeb S, Jafra S. When Genome-Based Approach Meets the "Old but Good": Revealing Genes Involved in the Antibacterial Activity of Pseudomonas sp. P482 against Soft Rot Pathogens. Front Microbiol 2016; 7:782. [PMID: 27303376 PMCID: PMC4880745 DOI: 10.3389/fmicb.2016.00782] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/09/2016] [Indexed: 11/13/2022] Open
Abstract
Dickeya solani and Pectobacterium carotovorum subsp. brasiliense are recently established species of bacterial plant pathogens causing black leg and soft rot of many vegetables and ornamental plants. Pseudomonas sp. strain P482 inhibits the growth of these pathogens, a desired trait considering the limited measures to combat these diseases. In this study, we determined the genetic background of the antibacterial activity of P482, and established the phylogenetic position of this strain. Pseudomonas sp. P482 was classified as Pseudomonas donghuensis. Genome mining revealed that the P482 genome does not contain genes determining the synthesis of known antimicrobials. However, the ClusterFinder algorithm, designed to detect atypical or novel classes of secondary metabolite gene clusters, predicted 18 such clusters in the genome. Screening of a Tn5 mutant library yielded an antimicrobial negative transposon mutant. The transposon insertion was located in a gene encoding an HpcH/HpaI aldolase/citrate lyase family protein. This gene is located in a hypothetical cluster predicted by the ClusterFinder, together with the downstream homologs of four nfs genes, that confer production of a non-fluorescent siderophore by P. donghuensis HYST. Site-directed inactivation of the HpcH/HpaI aldolase gene, the adjacent short chain dehydrogenase gene, as well as a homolog of an essential nfs cluster gene, all abolished the antimicrobial activity of the P482, suggesting their involvement in a common biosynthesis pathway. However, none of the mutants showed a decreased siderophore yield, neither was the antimicrobial activity of the wild type P482 compromised by high iron bioavailability. A genomic region comprising the nfs cluster and three upstream genes is involved in the antibacterial activity of P. donghuensis P482 against D. solani and P. carotovorum subsp. brasiliense. The genes studied are unique to the two known P. donghuensis strains. This study illustrates that mining of microbial genomes is a powerful approach for predictingthe presence of novel secondary-metabolite encoding genes especially when coupled with transposon mutagenesis.
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Affiliation(s)
- Dorota M Krzyżanowska
- Laboratory of Biological Plant Protection, Department of Biotechnology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Adam Ossowicki
- Laboratory of Biological Plant Protection, Department of Biotechnology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Magdalena Rajewska
- Laboratory of Biological Plant Protection, Department of Biotechnology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Tomasz Maciąg
- Laboratory of Biological Plant Protection, Department of Biotechnology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Magdalena Jabłońska
- Laboratory of Biological Plant Protection, Department of Biotechnology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Michał Obuchowski
- Laboratory of Molecular Bacteriology, Department of Medical Biotechnology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Medical University of Gdansk Gdansk, Poland
| | - Stephan Heeb
- School of Life Sciences, Faculty of Medicine and Health Sciences, University of Nottingham Nottingham, UK
| | - Sylwia Jafra
- Laboratory of Biological Plant Protection, Department of Biotechnology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
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58
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Fujino Y, Tanoue R, Yokoyama T, Doi K. A tightly regulated expression system for E. coli using supersaturated silicic acid. Biotechnol Lett 2016; 38:1381-7. [PMID: 27146211 DOI: 10.1007/s10529-016-2118-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Accepted: 04/30/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To develop a new expression system regulated by a ferric uptake regulator in which silicic acid is used as an inducer. RESULTS Fur box (binding site for Fur) was substituted for the lac operator to regulate the expression of GFP with the lac promoter. Since the addition of supersaturated silicic acid invokes iron deficiency, supersaturated silicic acids were used as an inducer. GFP expression was dependent on silica concentration, and the expression level without silica was negligible. Basal expression level of this lac-Fur system was extremely low and, hence, lytic enzyme gene E from bacteriophage ϕX174 could be retained in this system. Furthermore, the expression of genes of interest was spontaneously initiated as the cell density increased and the costs of the inducer are considerably less than IPTG. CONCLUSION The combination of lac promoter and Ferric uptake repressor allowed the protein expression by supersaturated silicic acid as an inducer in an easy and cost-effective way.
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Affiliation(s)
- Yasuhiro Fujino
- Faculty of Art and Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Ryo Tanoue
- Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Takushi Yokoyama
- Department of Chemistry, Faculty of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Katsumi Doi
- Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
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59
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Nguyen MP, Park J, Cho MH, Lee SW. Role of DetR in defence is critical for virulence of Xanthomonas oryzae pv. oryzae. MOLECULAR PLANT PATHOLOGY 2016; 17:601-13. [PMID: 26315668 PMCID: PMC6638461 DOI: 10.1111/mpp.12305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Like other bacteria, Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial leaf blight disease in rice, possesses intracellular signalling systems, known as two-component regulatory systems (TCSs), which regulate pathogenesis and biological processes. Completion of the genome sequences of three Xoo strains has facilitated the functional study of genes, including those of TCSs, but the biological functions of most Xoo TCSs have not yet been uncovered. To identify TCSs involved in Xoo pathogenesis, we generated knockout strains lacking response regulators (RRs, a cytoplasmic signalling component of the TCS) and examined the virulence of the RR knockout strains. This study presents a knockout strain (detR(-) ) lacking the PXO_04659 gene which shows dramatically reduced virulence relative to the wild-type. Our studies to elucidate detR function in Xoo pathogenesis revealed a reduction in extracellular polysaccharide (EPS), intolerance to reactive oxygen species (ROS) and deregulation of iron homeostasis in the detR(-) strain. Moreover, gene expression of regulatory factors, including other RRs and transcription factors (TFs), was altered in the absence of DetR protein, as determined by reverse transcription-polymerase chain reaction (RT-PCR) and/or real-time quantitative RT-PCR analyses. All evidence leads to the conclusion that DetR is essential for Xoo virulence through the regulation of the Xoo defence system including EPS synthesis, ROS detoxification and iron homeostasis, solely or cooperatively with other regulatory factors.
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Affiliation(s)
- Minh-Phuong Nguyen
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
- Institute of Crop Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
| | - Jongchan Park
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
- Institute of Crop Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
| | - Man-Ho Cho
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
| | - Sang-Won Lee
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
- Institute of Crop Biotechnology, Kyung Hee University, Yongin, 446-701, South Korea
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60
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Arbel-Goren R, Tal A, Parasar B, Dym A, Costantino N, Muñoz-García J, Court DL, Stavans J. Transcript degradation and noise of small RNA-controlled genes in a switch activated network in Escherichia coli. Nucleic Acids Res 2016; 44:6707-20. [PMID: 27085802 PMCID: PMC5001584 DOI: 10.1093/nar/gkw273] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 04/05/2016] [Indexed: 12/20/2022] Open
Abstract
Post-transcriptional regulatory processes may change transcript levels and affect cell-to-cell variability or noise. We study small-RNA downregulation to elucidate its effects on noise in the iron homeostasis network of Escherichia coli. In this network, the small-RNA RyhB undergoes stoichiometric degradation with the transcripts of target genes in response to iron stress. Using single-molecule fluorescence in situ hybridization, we measured transcript numbers of the RyhB-regulated genes sodB and fumA in individual cells as a function of iron deprivation. We observed a monotonic increase of noise with iron stress but no evidence of theoretically predicted, enhanced stoichiometric fluctuations in transcript numbers, nor of bistable behavior in transcript distributions. Direct detection of RyhB in individual cells shows that its noise is much smaller than that of these two targets, when RyhB production is significant. A generalized two-state model of bursty transcription that neglects RyhB fluctuations describes quantitatively the dependence of noise and transcript distributions on iron deprivation, enabling extraction of in vivo RyhB-mediated transcript degradation rates. The transcripts’ threshold-linear behavior indicates that the effective in vivo interaction strength between RyhB and its two target transcripts is comparable. Strikingly, the bacterial cell response exhibits Fur-dependent, switch-like activation instead of a graded response to iron deprivation.
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Affiliation(s)
- Rinat Arbel-Goren
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Asaf Tal
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Bibudha Parasar
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alvah Dym
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Nina Costantino
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Javier Muñoz-García
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel Departamento de Matemáticas and GISC, Universidad Carlos III de Madrid, Av. de la Universidad 30, 28911 Leganés, Madrid, Spain
| | - Donald L Court
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Joel Stavans
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
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de Paiva JB, da Silva LPM, Casas MRT, Conceição RA, Nakazato G, de Pace F, Sperandio V, da Silveira WD. In vivoinfluence ofin vitroup-regulated genes in the virulence of an APEC strain associated with swollen head syndrome. Avian Pathol 2016; 45:94-105. [DOI: 10.1080/03079457.2015.1125995] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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62
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Payne SM, Mey AR, Wyckoff EE. Vibrio Iron Transport: Evolutionary Adaptation to Life in Multiple Environments. Microbiol Mol Biol Rev 2016; 80:69-90. [PMID: 26658001 PMCID: PMC4711184 DOI: 10.1128/mmbr.00046-15] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Iron is an essential element for Vibrio spp., but the acquisition of iron is complicated by its tendency to form insoluble ferric complexes in nature and its association with high-affinity iron-binding proteins in the host. Vibrios occupy a variety of different niches, and each of these niches presents particular challenges for acquiring sufficient iron. Vibrio species have evolved a wide array of iron transport systems that allow the bacteria to compete for this essential element in each of its habitats. These systems include the secretion and uptake of high-affinity iron-binding compounds (siderophores) as well as transport systems for iron bound to host complexes. Transporters for ferric and ferrous iron not complexed to siderophores are also common to Vibrio species. Some of the genes encoding these systems show evidence of horizontal transmission, and the ability to acquire and incorporate additional iron transport systems may have allowed Vibrio species to more rapidly adapt to new environmental niches. While too little iron prevents growth of the bacteria, too much can be lethal. The appropriate balance is maintained in vibrios through complex regulatory networks involving transcriptional repressors and activators and small RNAs (sRNAs) that act posttranscriptionally. Examination of the number and variety of iron transport systems found in Vibrio spp. offers insights into how this group of bacteria has adapted to such a wide range of habitats.
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Affiliation(s)
- Shelley M Payne
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Alexandra R Mey
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Elizabeth E Wyckoff
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
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63
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Eid R, Boucher E, Gharib N, Khoury C, Arab NTT, Murray A, Young PG, Mandato CA, Greenwood MT. Identification of human ferritin, heavy polypeptide 1 (FTH1) and yeast RGI1 (YER067W) as pro-survival sequences that counteract the effects of Bax and copper in Saccharomyces cerevisiae. Exp Cell Res 2016; 342:52-61. [PMID: 26886577 DOI: 10.1016/j.yexcr.2016.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/09/2016] [Accepted: 02/12/2016] [Indexed: 02/06/2023]
Abstract
Ferritin is a sub-family of iron binding proteins that form multi-subunit nanotype iron storage structures and prevent oxidative stress induced apoptosis. Here we describe the identification and characterization of human ferritin, heavy polypeptide 1 (FTH1) as a suppressor of the pro-apoptotic murine Bax sequence in yeast. In addition we demonstrate that FTH1 is a general pro-survival sequence since it also prevents the cell death inducing effects of copper when heterologously expressed in yeast. Although ferritins are phylogenetically widely distributed and are present in most species of Bacteria, Archaea and Eukarya, ferritin is conspicuously absent in most fungal species including Saccharomyces cerevisiae. An in silico analysis of the yeast proteome lead to the identification of the 161 residue RGI1 (YER067W) encoded protein as a candidate for being a yeast ferritin. In addition to sharing 20% sequence identity with the 183 residue FTH1, RGI1 also has similar pro-survival properties as ferritin when overexpressed in yeast. Analysis of recombinant protein by SDS-PAGE and by electron microscopy revealed the expected formation of higher-order structures for FTH1 that was not observed with Rgi1p. Further analysis revealed that cells overexpressing RGI1 do not show increased resistance to iron toxicity and do not have enhanced capacity to store iron. In contrast, cells lacking RGI1 were found to be hypersensitive to the toxic effects of iron. Overall, our results suggest that Rgi1p is a novel pro-survival protein whose function is not related to ferritin but nevertheless it may have a role in regulating yeast sensitivity to iron stress.
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Affiliation(s)
- Rawan Eid
- Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada; Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Eric Boucher
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Nada Gharib
- Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada
| | - Chamel Khoury
- Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada; Department of Biology, Queen's University, Kingston, Ontario, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Nagla T T Arab
- Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada; Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Alistair Murray
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Paul G Young
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Craig A Mandato
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Michael T Greenwood
- Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada.
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Bradley JM, Le Brun NE, Moore GR. Ferritins: furnishing proteins with iron. J Biol Inorg Chem 2016; 21:13-28. [PMID: 26825805 PMCID: PMC4771812 DOI: 10.1007/s00775-016-1336-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/06/2016] [Indexed: 12/04/2022]
Abstract
Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores, consider how iron might be released from ferritins, and examine in detail how three selected ferritins oxidise Fe2+ to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins.
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Affiliation(s)
- Justin M Bradley
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Geoffrey R Moore
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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65
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Snoussi S, El May A, Coquet L, Chan P, Jouenne T, Dé E, Landoulsi A. Unraveling the effects of static magnetic field stress on cytosolic proteins of Salmonella by using a proteomic approach. Can J Microbiol 2015; 62:338-48. [PMID: 26928316 DOI: 10.1139/cjm-2015-0532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study investigated the adaptation of Salmonella enterica subsp. enterica serovar Hadar to static magnetic field (SMF) exposure (200 mT, 9 h). The proteomic analysis provides an overview of potentially important cytosolic proteins that Salmonella needs to regulate to survive and adapt to magnetic stress. Via 2-dimensional electrophoresis and liquid chromatography tandem mass spectrometry, we compared cytosolic proteomes before and after exposure to magnetic field. A total of 35 proteins displaying more than a 2-fold change were differentially expressed in exposed cells, among which 25 were upregulated and 10 were downregulated. These proteins can be classified mainly into 6 categories: (i) proteins involved in metabolic pathways of carbohydrates, (ii) chaperones and proteins produced in response to oxidative stress, (iii) proteins involved in energy homeostasis, (iv) elongation factors (EF-Tu and EF-Ts), (v) proteins involved in motility, and (vi) proteins involved in molecules transport. Many of the presented observations could be explained, while some represent still-unknown mechanisms. In addition, this study reveals 5 hypothetical proteins. It seems that the stress response to SMF (200 mT) is essentially set up to avoid oxidative damages, with the overexpression of proteins directly involved in oxidative stress response and metabolic switches to counteract oxidative stress. Interestingly, several proteins induced under SMF exposure are found to overlap with those induced by other stresses, such as heat shock and starvation.
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Affiliation(s)
- Sarra Snoussi
- a Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisie.,b UMR 6270 CNRS, Faculté des sciences, Université de Rouen, 76821 Mont Saint Aignan Cedex, France
| | - Alya El May
- a Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisie
| | - Laurent Coquet
- b UMR 6270 CNRS, Faculté des sciences, Université de Rouen, 76821 Mont Saint Aignan Cedex, France
| | - Philippe Chan
- b UMR 6270 CNRS, Faculté des sciences, Université de Rouen, 76821 Mont Saint Aignan Cedex, France
| | - Thierry Jouenne
- b UMR 6270 CNRS, Faculté des sciences, Université de Rouen, 76821 Mont Saint Aignan Cedex, France
| | - Emmanuelle Dé
- b UMR 6270 CNRS, Faculté des sciences, Université de Rouen, 76821 Mont Saint Aignan Cedex, France
| | - Ahmed Landoulsi
- a Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisie
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66
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Rodríguez-Rojas A, Makarova O, Müller U, Rolff J. Cationic Peptides Facilitate Iron-induced Mutagenesis in Bacteria. PLoS Genet 2015; 11:e1005546. [PMID: 26430769 PMCID: PMC4592263 DOI: 10.1371/journal.pgen.1005546] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/01/2015] [Indexed: 11/19/2022] Open
Abstract
Pseudomonas aeruginosa is the causative agent of chronic respiratory infections and is an important pathogen of cystic fibrosis patients. Adaptive mutations play an essential role for antimicrobial resistance and persistence. The factors that contribute to bacterial mutagenesis in this environment are not clear. Recently it has been proposed that cationic antimicrobial peptides such as LL-37 could act as mutagens in P. aeruginosa. Here we provide experimental evidence that mutagenesis is the product of a joint action of LL-37 and free iron. By estimating mutation rate, mutant frequencies and assessing mutational spectra in P. aeruginosa treated either with LL-37, iron or a combination of both we demonstrate that mutation rate and mutant frequency were increased only when free iron and LL-37 were present simultaneously. Colistin had the same effect. The addition of an iron chelator completely abolished this mutagenic effect, suggesting that LL-37 enables iron to enter the cells resulting in DNA damage by Fenton reactions. This was also supported by the observation that the mutational spectrum of the bacteria under LL-37-iron regime showed one of the characteristic Fenton reaction fingerprints: C to T transitions. Free iron concentration in nature and within hosts is kept at a very low level, but the situation in infected lungs of cystic fibrosis patients is different. Intermittent bleeding and damage to the epithelial cells in lungs may contribute to the release of free iron that in turn leads to generation of reactive oxygen species and deterioration of the respiratory tract, making it more susceptible to the infection.
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Affiliation(s)
- Alexandro Rodríguez-Rojas
- Evolutionary Biology, Institute for Biology, Free University Berlin, Berlin, Germany
- * E-mail: (ARR); (JR)
| | - Olga Makarova
- Evolutionary Biology, Institute for Biology, Free University Berlin, Berlin, Germany
| | - Uta Müller
- Evolutionary Biology, Institute for Biology, Free University Berlin, Berlin, Germany
| | - Jens Rolff
- Evolutionary Biology, Institute for Biology, Free University Berlin, Berlin, Germany
- * E-mail: (ARR); (JR)
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Folsom JP, Carlson RP. Physiological, biomass elemental composition and proteomic analyses of Escherichia coli ammonium-limited chemostat growth, and comparison with iron- and glucose-limited chemostat growth. MICROBIOLOGY (READING, ENGLAND) 2015; 161:1659-1670. [PMID: 26018546 PMCID: PMC4681042 DOI: 10.1099/mic.0.000118] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/22/2015] [Indexed: 01/02/2023]
Abstract
Escherichia coli physiological, biomass elemental composition and proteome acclimations to ammonium-limited chemostat growth were measured at four levels of nutrient scarcity controlled via chemostat dilution rate. These data were compared with published iron- and glucose-limited growth data collected from the same strain and at the same dilution rates to quantify general and nutrient-specific responses. Severe nutrient scarcity resulted in an overflow metabolism with differing organic byproduct profiles based on limiting nutrient and dilution rate. Ammonium-limited cultures secreted up to 35% of the metabolized glucose carbon as organic byproducts with acetate representing the largest fraction; in comparison, iron-limited cultures secreted up to 70 % of the metabolized glucose carbon as lactate, and glucose-limited cultures secreted up to 4% of the metabolized glucose carbon as formate. Biomass elemental composition differed with nutrient limitation; biomass from ammonium-limited cultures had a lower nitrogen content than biomass from either iron- or glucose-limited cultures. Proteomic analysis of central metabolism enzymes revealed that ammonium- and iron-limited cultures had a lower abundance of key tricarboxylic acid (TCA) cycle enzymes and higher abundance of key glycolysis enzymes compared with glucose-limited cultures. The overall results are largely consistent with cellular economics concepts, including metabolic tradeoff theory where the limiting nutrient is invested into essential pathways such as glycolysis instead of higher ATP-yielding, but non-essential, pathways such as the TCA cycle. The data provide a detailed insight into ecologically competitive metabolic strategies selected by evolution, templates for controlling metabolism for bioprocesses and a comprehensive dataset for validating in silico representations of metabolism.
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Affiliation(s)
- James Patrick Folsom
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | - Ross P. Carlson
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
- Thermal Biology Institute, Montana State University, Bozeman, MT, USA
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68
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The DNA-Binding Protein from Starved Cells (Dps) Utilizes Dual Functions To Defend Cells against Multiple Stresses. J Bacteriol 2015. [PMID: 26216848 DOI: 10.1128/jb.00475-15] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Bacteria deficient in the DNA-binding protein from starved cells (Dps) are viable under controlled conditions but show dramatically increased mortality rates when exposed to any of a wide range of stresses, including starvation, oxidative stress, metal toxicity, or thermal stress. It remains unclear whether the protective action of Dps against specific stresses derives from its DNA-binding activity, which may exclude destructive agents from the chromosomal region, or its ferroxidase activity, which neutralizes and sequesters potentially damaging chemical species. To resolve this question, we have identified the critical residues of Escherichia coli Dps that bind to DNA and modulate iron oxidation. We uncoupled the biochemical activities of Dps, creating Dps variants and mutant E. coli strains that are defective in either DNA-binding or ferroxidase activity. Quantification of the contribution of each activity to the protection of DNA integrity and cellular viability revealed that both activities of Dps are required in order to counteract many differing stresses. These findings demonstrate that Dps plays a multipurpose role in stress protection via its dual activities, explaining how Dps can be of vital importance to bacterial viability over a wide range of stresses. IMPORTANCE The DNA-binding protein from starved cells (Dps) protects bacterial cells against many different types of stressors. We find that DNA binding and iron oxidation by Dps are performed completely independently of each other. Both biochemical activities are required to protect E. coli against stressors, as well as to protect DNA from oxidative damage in vitro. These results suggest that many stressors may cause both oxidative stress and direct DNA damage.
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69
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Shi M, Wan F, Mao Y, Gao H. Unraveling the Mechanism for the Viability Deficiency of Shewanella oneidensis oxyR Null Mutant. J Bacteriol 2015; 197:2179-2189. [PMID: 25897035 PMCID: PMC4455265 DOI: 10.1128/jb.00154-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 04/16/2015] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Oxidative stresses triggered by reactive oxygen species (ROS) that damage various cellular components are unavoidable for virtually all living organisms. In defense, microorganisms have evolved sophisticated mechanisms to sense, respond to, and battle against ROS. Shewanella oneidensis, an important research model for applied and environmental microbes, employs OxyR to mediate the response to H2O2 by derepressing the production of the major H2O2 scavenger KatB as a major means toward these goals. Surprisingly, despite enhanced H2O2 degradation, the oxyR mutant carries a viability deficiency phenotype (plating defect), which can be suppressed by the addition of exogenous iron species. Experiments showed that the defect was not due to iron starvation. Rather, multiple lines of evidence suggested that H2O2 generated abiotically in lysogeny broth (LB) is responsible for the defect by quickly killing mutant cells. We then showed that the iron species suppressed the plating defect by two distinct mechanisms, either as an H2O2 scavenger without involving living cells or as an environmental cue to stimulate an OxyR-independent response to help cells cope with oxidative stress. Based on the suppression of the plating defect by overproduction of H2O2 scavengers in vivo, we propose that cellular components that are vulnerable to H2O2 and responsible for the defect may reside outside the cytoplasm. IMPORTANCE In bacteria, OxyR is the major regulator controlling the cellular response to H2O2. The loss of OxyR results in reduced viability in many species, but the underlying mechanism is unknown. We showed in S. oneidensis that this defect was due to H2O2 generated abiotically in LB. We then showed that this defect could be corrected by the addition of Fe(2+) or catalase to the LB or increased intracellular production of catalase. Further analyses revealed that Fe(2+) was able not only to decompose H2O2 directly but also to stimulate the activity of OxyR-independent H2O2-scavenging enzymes. Our data indicate that iron species play a previously underappreciated role in protecting cells from H2O2 in environments.
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Affiliation(s)
- Miaomiao Shi
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
| | - Fen Wan
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
| | - Yinting Mao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
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Eckelt E, Meißner T, Meens J, Laarmann K, Nerlich A, Jarek M, Weiss S, Gerlach GF, Goethe R. FurA contributes to the oxidative stress response regulation of Mycobacterium avium ssp. paratuberculosis. Front Microbiol 2015; 6:16. [PMID: 25705205 PMCID: PMC4319475 DOI: 10.3389/fmicb.2015.00016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/07/2015] [Indexed: 11/13/2022] Open
Abstract
The ferric uptake regulator A (FurA) is known to be involved in iron homeostasis and stress response in many bacteria. In mycobacteria the precise role of FurA is still unclear. In the presented study, we addressed the functional role of FurA in the ruminant pathogen Mycobacterium avium ssp. paratuberculosis (MAP) by construction of a furA deletion strain (MAPΔfurA). RNA deep sequencing revealed that the FurA regulon consists of repressed and activated genes associated to stress response or intracellular survival. Not a single gene related to metal homeostasis was affected by furA deletion. A decisive role of FurA during intracellular survival in macrophages was shown by significantly enhanced survival of MAPΔfurA compared to the wildtype, indicating that a principal task of mycobacterial FurA is oxidative stress response regulation in macrophages. This resistance was not associated with altered survival of mice after long term infection with MAP. Our results demonstrate for the first time, that mycobacterial FurA is not involved in the regulation of iron homeostasis. However, they provide strong evidence that FurA contributes to intracellular survival as an oxidative stress sensing regulator.
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Affiliation(s)
- Elke Eckelt
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
| | - Thorsten Meißner
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
| | - Jochen Meens
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
| | - Kristin Laarmann
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
| | - Andreas Nerlich
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
| | - Michael Jarek
- Genome Analytics, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Siegfried Weiss
- Molecular Immunology, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Gerald-F Gerlach
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
| | - Ralph Goethe
- Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover Hannover, Germany
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Mashruwala AA, Pang YY, Rosario-Cruz Z, Chahal HK, Benson MA, Anzaldi-Mike LL, Skaar EP, Torres VJ, Nauseef WM, Boyd JM. Nfu facilitates the maturation of iron-sulfur proteins and participates in virulence in Staphylococcus aureus. Mol Microbiol 2015; 95:383-409. [PMID: 25388433 PMCID: PMC4428306 DOI: 10.1111/mmi.12860] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2014] [Indexed: 01/21/2023]
Abstract
The acquisition and metabolism of iron (Fe) by the human pathogen Staphylococcus aureus is critical for disease progression. S. aureus requires Fe to synthesize inorganic cofactors called iron-sulfur (Fe-S) clusters, which are required for functional Fe-S proteins. In this study we investigated the mechanisms utilized by S. aureus to metabolize Fe-S clusters. We identified that S. aureus utilizes the Suf biosynthetic system to synthesize Fe-S clusters and we provide genetic evidence suggesting that the sufU and sufB gene products are essential. Additional biochemical and genetic analyses identified Nfu as an Fe-S cluster carrier, which aids in the maturation of Fe-S proteins. We find that deletion of the nfu gene negatively impacts staphylococcal physiology and pathogenicity. A nfu mutant accumulates both increased intracellular non-incorporated Fe and endogenous reactive oxygen species (ROS) resulting in DNA damage. In addition, a strain lacking Nfu is sensitive to exogenously supplied ROS and reactive nitrogen species. Congruous with ex vivo findings, a nfu mutant strain is more susceptible to oxidative killing by human polymorphonuclear leukocytes and displays decreased tissue colonization in a murine model of infection. We conclude that Nfu is necessary for staphylococcal pathogenesis and establish Fe-S cluster metabolism as an attractive antimicrobial target.
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Affiliation(s)
- Ameya A. Mashruwala
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
| | - Yun Y. Pang
- Inflammation Program and Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, IA 52240
| | - Zuelay Rosario-Cruz
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
| | - Harsimranjit K. Chahal
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
| | - Meredith A. Benson
- Department of Microbiology, NYU Langone Medical Center, New York, NY 10016
| | - Laura L. Anzaldi-Mike
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Victor J. Torres
- Department of Microbiology, NYU Langone Medical Center, New York, NY 10016
| | - William M. Nauseef
- Inflammation Program and Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, IA 52240
| | - Jeffrey M. Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
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Roche B, Huguenot A, Barras F, Py B. The iron-binding CyaY and IscX proteins assist the ISC-catalyzed Fe-S biogenesis in Escherichia coli. Mol Microbiol 2015; 95:605-23. [PMID: 25430730 DOI: 10.1111/mmi.12888] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2014] [Indexed: 01/18/2023]
Abstract
In eukaryotes, frataxin deficiency (FXN) causes severe phenotypes including loss of iron-sulfur (Fe-S) cluster protein activity, accumulation of mitochondrial iron and leads to the neurodegenerative disease Friedreich's ataxia. In contrast, in prokaryotes, deficiency in the FXN homolog, CyaY, was reported not to cause any significant phenotype, questioning both its importance and its actual contribution to Fe-S cluster biogenesis. Because FXN is conserved between eukaryotes and prokaryotes, this surprising discrepancy prompted us to reinvestigate the role of CyaY in Escherichia coli. We report that CyaY (i) potentiates E. coli fitness, (ii) belongs to the ISC pathway catalyzing the maturation of Fe-S cluster-containing proteins and (iii) requires iron-rich conditions for its contribution to be significant. A genetic interaction was discovered between cyaY and iscX, the last gene of the isc operon. Deletion of both genes showed an additive effect on Fe-S cluster protein maturation, which led, among others, to increased resistance to aminoglycosides and increased sensitivity to lambda phage infection. Together, these in vivo results establish the importance of CyaY as a member of the ISC-mediated Fe-S cluster biogenesis pathway in E. coli, like it does in eukaryotes, and validate IscX as a new bona fide Fe-S cluster biogenesis factor.
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Affiliation(s)
- Béatrice Roche
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13009, Marseille, France
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Hitchings MD, Townsend P, Pohl E, Facey PD, Jones DH, Dyson PJ, Del Sol R. A tale of tails: deciphering the contribution of terminal tails to the biochemical properties of two Dps proteins from Streptomyces coelicolor. Cell Mol Life Sci 2014; 71:4911-26. [PMID: 24915944 PMCID: PMC11113173 DOI: 10.1007/s00018-014-1658-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/07/2014] [Accepted: 05/23/2014] [Indexed: 10/25/2022]
Abstract
Dps proteins are members of an extensive family of proteins that oxidise and deposit iron in the form of ferric oxide, and are also able to bind DNA. Ferroxidation centres are formed at the interface of anti-parallel dimers, which further assemble into dodecameric nanocages with a hollow core where ferric oxide is deposited. Streptomyces coelicolor encodes three Dps-like proteins (DpsA, B and C). Despite sharing the conserved four-helix bundle organisation observed in members of the Dps family, they display significant differences in the length of terminal extensions, or tails. DpsA possess both N- and C-terminal tails of different lengths, and their removal affects quaternary structure assembly to varying degrees. DpsC quaternary structure, on the other hand, is heavily dependent on its N-terminal tail as its removal abolishes correct protein folding. Analysis of the crystal structure of dodecamers from both proteins revealed remarkable differences in the position of tails and interface surface area; and provides insight to explain the differences in biochemical behaviour observed while comparing DpsA and DpsC.
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Affiliation(s)
| | - Philip Townsend
- Department of Chemistry, School of Biological and Biomedical Sciences, University Science Laboratories, Durham University, South Road, Durham, DH1 3LE UK
| | - Ehmke Pohl
- Department of Chemistry, School of Biological and Biomedical Sciences, University Science Laboratories, Durham University, South Road, Durham, DH1 3LE UK
| | - Paul D. Facey
- College of Medicine, Swansea University, Singleton Park, Swansea, SA2 8PP UK
| | - D. Hugh Jones
- College of Medicine, Swansea University, Singleton Park, Swansea, SA2 8PP UK
| | - Paul J. Dyson
- College of Medicine, Swansea University, Singleton Park, Swansea, SA2 8PP UK
| | - Ricardo Del Sol
- College of Medicine, Swansea University, Singleton Park, Swansea, SA2 8PP UK
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Butler CA, Dashper SG, Zhang L, Seers CA, Mitchell HL, Catmull DV, Glew MD, Heath JE, Tan Y, Khan HSG, Reynolds EC. The Porphyromonas gingivalis ferric uptake regulator orthologue binds hemin and regulates hemin-responsive biofilm development. PLoS One 2014; 9:e111168. [PMID: 25375181 PMCID: PMC4222909 DOI: 10.1371/journal.pone.0111168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/26/2014] [Indexed: 12/27/2022] Open
Abstract
Porphyromonas gingivalis is a Gram-negative pathogen associated with the biofilm-mediated disease chronic periodontitis. P. gingivalis biofilm formation is dependent on environmental heme for which P. gingivalis has an obligate requirement as it is unable to synthesize protoporphyrin IX de novo, hence P. gingivalis transports iron and heme liberated from the human host. Homeostasis of a variety of transition metal ions is often mediated in Gram-negative bacteria at the transcriptional level by members of the Ferric Uptake Regulator (Fur) superfamily. P. gingivalis has a single predicted Fur superfamily orthologue which we have designated Har (heme associated regulator). Recombinant Har formed dimers in the presence of Zn2+ and bound one hemin molecule per monomer with high affinity (Kd of 0.23 µM). The binding of hemin resulted in conformational changes of Zn(II)Har and residue 97Cys was involved in hemin binding as part of a predicted -97C-98P-99L- hemin binding motif. The expression of 35 genes was down-regulated and 9 up-regulated in a Har mutant (ECR455) relative to wild-type. Twenty six of the down-regulated genes were previously found to be up-regulated in P. gingivalis grown as a biofilm and 11 were up-regulated under hemin limitation. A truncated Zn(II)Har bound the promoter region of dnaA (PGN_0001), one of the up-regulated genes in the ECR455 mutant. This binding decreased as hemin concentration increased which was consistent with gene expression being regulated by hemin availability. ECR455 formed significantly less biofilm than the wild-type and unlike wild-type biofilm formation was independent of hemin availability. P. gingivalis possesses a hemin-binding Fur orthologue that regulates hemin-dependent biofilm formation.
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Affiliation(s)
- Catherine A. Butler
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Stuart G. Dashper
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Lianyi Zhang
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Christine A. Seers
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Helen L. Mitchell
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Deanne V. Catmull
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Michelle D. Glew
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Jacqueline E. Heath
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Yan Tan
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Hasnah S. G. Khan
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
| | - Eric C. Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Victoria, Australia
- * E-mail:
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Becerra G, Merchán F, Blasco R, Igeño MI. Characterization of a ferric uptake regulator (Fur)-mutant of the cyanotrophic bacterium Pseudomonas pseudoalcaligenes CECT5344. J Biotechnol 2014; 190:2-10. [DOI: 10.1016/j.jbiotec.2014.03.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/17/2014] [Accepted: 03/25/2014] [Indexed: 11/25/2022]
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76
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Brennan CM, Mazzucca NQ, Mezoian T, Hunt TM, Keane ML, Leonard JN, Scola SE, Beer EN, Perdue S, Pellock BJ. Reduced heme levels underlie the exponential growth defect of the Shewanella oneidensis hfq mutant. PLoS One 2014; 9:e109879. [PMID: 25356668 PMCID: PMC4214671 DOI: 10.1371/journal.pone.0109879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/03/2014] [Indexed: 11/18/2022] Open
Abstract
The RNA chaperone Hfq fulfills important roles in small regulatory RNA (sRNA) function in many bacteria. Loss of Hfq in the dissimilatory metal reducing bacterium Shewanella oneidensis strain MR-1 results in slow exponential phase growth and a reduced terminal cell density at stationary phase. We have found that the exponential phase growth defect of the hfq mutant in LB is the result of reduced heme levels. Both heme levels and exponential phase growth of the hfq mutant can be completely restored by supplementing LB medium with 5-aminolevulinic acid (5-ALA), the first committed intermediate synthesized during heme synthesis. Increasing expression of gtrA, which encodes the enzyme that catalyzes the first step in heme biosynthesis, also restores heme levels and exponential phase growth of the hfq mutant. Taken together, our data indicate that reduced heme levels are responsible for the exponential growth defect of the S. oneidensis hfq mutant in LB medium and suggest that the S. oneidensis hfq mutant is deficient in heme production at the 5-ALA synthesis step.
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Affiliation(s)
- Christopher M. Brennan
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Nicholas Q. Mazzucca
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Taylor Mezoian
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Taylor M. Hunt
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Meaghan L. Keane
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Jessica N. Leonard
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Shelby E. Scola
- Department of Chemistry and Biochemistry, Providence College, Providence, Rhode Island, United States of America
| | - Emma N. Beer
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Sarah Perdue
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
| | - Brett J. Pellock
- Department of Biology, Providence College, Providence, Rhode Island, United States of America
- * E-mail:
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77
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Méhi O, Bogos B, Csörgő B, Pál F, Nyerges A, Papp B, Pál C. Perturbation of iron homeostasis promotes the evolution of antibiotic resistance. Mol Biol Evol 2014; 31:2793-804. [PMID: 25063442 PMCID: PMC4166929 DOI: 10.1093/molbev/msu223] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Evolution of antibiotic resistance in microbes is frequently achieved by acquisition of spontaneous mutations during antimicrobial therapy. Here, we demonstrate that inactivation of a central transcriptional regulator of iron homeostasis (Fur) facilitates laboratory evolution of ciprofloxacin resistance in Escherichia coli. To decipher the underlying molecular mechanisms, we first performed a global transcriptome analysis and demonstrated that the set of genes regulated by Fur changes substantially in response to antibiotic treatment. We hypothesized that the impact of Fur on evolvability under antibiotic pressure is due to the elevated intracellular concentration of free iron and the consequent enhancement of oxidative damage-induced mutagenesis. In agreement with expectations, overexpression of iron storage proteins, inhibition of iron transport, or anaerobic conditions drastically suppressed the evolution of resistance, whereas inhibition of the SOS response-mediated mutagenesis had only a minor effect. Finally, we provide evidence that a cell permeable iron chelator inhibits the evolution of resistance. In sum, our work revealed the central role of iron metabolism in the de novo evolution of antibiotic resistance, a pattern that could influence the development of novel antimicrobial strategies.
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Affiliation(s)
- Orsolya Méhi
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Balázs Bogos
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Bálint Csörgő
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Ferenc Pál
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Akos Nyerges
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Csaba Pál
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
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78
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Alenkina I, Oshtrakh M, Tugarova A, Biró B, Semionkin V, Kamnev A. Study of the rhizobacterium Azospirillum brasilense Sp245 using Mössbauer spectroscopy with a high velocity resolution: Implication for the analysis of ferritin-like iron cores. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.04.084] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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79
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Bertrand RL. Lag phase-associated iron accumulation is likely a microbial counter-strategy to host iron sequestration: role of the ferric uptake regulator (fur). J Theor Biol 2014; 359:72-9. [PMID: 24929040 DOI: 10.1016/j.jtbi.2014.05.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 05/19/2014] [Accepted: 05/27/2014] [Indexed: 01/26/2023]
Abstract
Iron is an essential metal for almost all forms of life, but potentiates oxidative stress via Fenton catalysis. During microbial lag phase there is a rapid influx of iron with concomitant oxidative hypersensitivity. How and why iron accumulation occurs remains to be elucidated. Iron homeostasis in prokaryotes is mediated by the ferric uptake regulator (Fur), an iron-activated global regulator that controls intracellular iron levels by feedback inhibition with the metal. Herein it is postulated, based on the expression profiles of antioxidant enzymes within the Fur regulon as observed in wild type and Δfur mutants, that iron accumulation is mediated by a transitively low concentration of the Fur protein during lag phase. Vertebrate hosts sequester iron upon 'sensing' an infection in order to retard microbial proliferation through a process known as 'nutritional immunity'. It is herein argued that the purpose of iron accumulation is not principally a preparative step for the replicative phase, as suggested elsewhere, but an evolved behavior that counteracts host iron sequestration. This interpretation is supported by multiple clinical and animal studies that demonstrate that iron surplus in hosts advances progression and susceptibility to infection, and vice versa. Contextualizing iron accumulation as a counter-immune behavior adds impetus to the development of antibiotics targeting pathogenic modes of iron acquisition.
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Affiliation(s)
- Robert L Bertrand
- Department of Chemistry, University of Winnipeg, Winnipeg, MB, Canada R3B 2E9.
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80
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Physiological and proteomic analysis of Escherichia coli iron-limited chemostat growth. J Bacteriol 2014; 196:2748-61. [PMID: 24837288 DOI: 10.1128/jb.01606-14] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Iron bioavailability is a major limiter of bacterial growth in mammalian host tissue and thus represents an important area of study. Escherichia coli K-12 metabolism was studied at four levels of iron limitation in chemostats using physiological and proteomic analyses. The data documented an E. coli acclimation gradient where progressively more severe iron scarcity resulted in a larger percentage of substrate carbon being directed into an overflow metabolism accompanied by a decrease in biomass yield on glucose. Acetate was the primary secreted organic by-product for moderate levels of iron limitation, but as stress increased, the metabolism shifted to secrete primarily lactate (∼70% of catabolized glucose carbon). Proteomic analysis reinforced the physiological data and quantified relative increases in glycolysis enzyme abundance and decreases in tricarboxylic acid (TCA) cycle enzyme abundance with increasing iron limitation stress. The combined data indicated that E. coli responds to limiting iron by investing the scarce resource in essential enzymes, at the cost of catabolic efficiency (i.e., downregulating high-ATP-yielding pathways containing enzymes with large iron requirements, like the TCA cycle). Acclimation to iron-limited growth was contrasted experimentally with acclimation to glucose-limited growth to identify both general and nutrient-specific acclimation strategies. While the iron-limited cultures maximized biomass yields on iron and increased expression of iron acquisition strategies, the glucose-limited cultures maximized biomass yields on glucose and increased expression of carbon acquisition strategies. This study quantified ecologically competitive acclimations to nutrient limitations, yielding knowledge essential for understanding medically relevant bacterial responses to host and to developing intervention strategies.
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81
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Bradley JM, Moore GR, Le Brun NE. Mechanisms of iron mineralization in ferritins: one size does not fit all. J Biol Inorg Chem 2014; 19:775-85. [PMID: 24748222 DOI: 10.1007/s00775-014-1136-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 04/07/2014] [Indexed: 12/23/2022]
Abstract
Significant progress has been made in recent years toward understanding the processes by which an iron mineral is deposited within members of the ferritin family of 24mer iron storage proteins, enabled by high-resolution structures together with spectroscopic and kinetic studies. These suggest common characteristics that are shared between ferritins, namely, a highly symmetric arrangement of subunits that provides a protein coat around a central cavity in which the mineral is formed, channels through the coat that facilitate ingress and egress of ions, and catalytic sites, called ferroxidase centers, that drive Fe(2+) oxidation. They also reveal significant variations in both structure and mechanism amongst ferritins. Here, we describe three general types of structurally distinct ferroxidase center and the mechanisms of mineralization that they are associated with. The highlighted variation leads us to conclude that there is no universal mechanism by which ferritins function, but instead there exists several distinct mechanisms of ferritin iron mineralization.
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Affiliation(s)
- Justin M Bradley
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, NR4 7TJ, UK
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82
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Adler C, Corbalan NS, Peralta DR, Pomares MF, de Cristóbal RE, Vincent PA. The alternative role of enterobactin as an oxidative stress protector allows Escherichia coli colony development. PLoS One 2014; 9:e84734. [PMID: 24392154 PMCID: PMC3879343 DOI: 10.1371/journal.pone.0084734] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 11/18/2013] [Indexed: 12/18/2022] Open
Abstract
Numerous bacteria have evolved different iron uptake systems with the ability to make use of their own and heterologous siderophores. However, there is growing evidence attributing alternative roles for siderophores that might explain the potential adaptive advantages of microorganisms having multiple siderophore systems. In this work, we show the requirement of the siderophore enterobactin for Escherichia coli colony development in minimal media. We observed that a strain impaired in enterobactin production (entE mutant) was unable to form colonies on M9 agar medium meanwhile its growth was normal on LB agar medium. Given that, neither iron nor citrate supplementation restored colony growth, the role of enterobactin as an iron uptake-facilitator would not explain its requirement for colony development. The absence of colony development was reverted either by addition of enterobactin, the reducing agent ascorbic acid or by incubating in anaerobic culture conditions with no additives. Then, we associated the enterobactin requirement for colony development with its ability to reduce oxidative stress, which we found to be higher in media where the colony development was impaired (M9) compared with media where the strain was able to form colonies (LB). Since oxyR and soxS mutants (two major stress response regulators) formed colonies in M9 agar medium, we hypothesize that enterobactin could be an important piece in the oxidative stress response repertoire, particularly required in the context of colony formation. In addition, we show that enterobactin has to be hydrolyzed after reaching the cell cytoplasm in order to enable colony development. By favoring iron release, hydrolysis of the enterobactin-iron complex, not only would assure covering iron needs, but would also provide the cell with a molecule with exposed hydroxyl groups (hydrolyzed enterobactin). This molecule would be able to scavenge radicals and therefore reduce oxidative stress.
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Affiliation(s)
- Conrado Adler
- Departamento de Bioquímica de la Nutrición, INSIBIO (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán) San Miguel de Tucumán, Tucumán, Argentina
| | - Natalia S. Corbalan
- Departamento de Bioquímica de la Nutrición, INSIBIO (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán) San Miguel de Tucumán, Tucumán, Argentina
| | - Daiana R. Peralta
- Departamento de Bioquímica de la Nutrición, INSIBIO (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán) San Miguel de Tucumán, Tucumán, Argentina
| | - María Fernanda Pomares
- Departamento de Bioquímica de la Nutrición, INSIBIO (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán) San Miguel de Tucumán, Tucumán, Argentina
| | - Ricardo E. de Cristóbal
- Departamento de Bioquímica de la Nutrición, INSIBIO (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán) San Miguel de Tucumán, Tucumán, Argentina
| | - Paula A. Vincent
- Departamento de Bioquímica de la Nutrición, INSIBIO (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán) San Miguel de Tucumán, Tucumán, Argentina
- * E-mail:
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83
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Calderón IL, Morales EH, Collao B, Calderón PF, Chahuán CA, Acuña LG, Gil F, Saavedra CP. Role of Salmonella Typhimurium small RNAs RyhB-1 and RyhB-2 in the oxidative stress response. Res Microbiol 2013; 165:30-40. [PMID: 24239962 DOI: 10.1016/j.resmic.2013.10.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 10/04/2013] [Indexed: 11/26/2022]
Abstract
As part of the response to specific stress conditions, bacteria express small molecules of non-coding RNA which maintain cellular homeostasis by regulating gene expression, commonly at the post-transcriptional level. Among these, in Salmonella enterica sv. Typhimurium, the paralog small non-coding RNAs RyhB-1 and RyhB-2 play an important role in iron homeostasis. In addition, in the present work, we show that RyhB-1 and RyhB-2 also participate in the response to hydrogen peroxide (H2O2). Deletion of RyhB-1 and/or RyhB-2 resulted in increased levels of intracellular reactive oxygen species, protein carbonylation and an altered NADH/NAD(+) ratio. Analyses of the transcriptional profiles of ryhB-1 and ryhB-2 by northern blot and qRT-PCR showed that they are induced in response to H2O2 in an OxyR-dependent manner. By using lacZ-fusions and electrophoretic mobility shift assays, we confirmed the requirement of OxyR for inducing expression of both ryhB-1 and ryhB-2. Taken together, our results support a model in which, in response to peroxide treatment, ryhB-1 and ryhB-2 are upregulated by OxyR through direct interaction with their promoter region.
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Affiliation(s)
- Iván L Calderón
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
| | - Eduardo H Morales
- Great Lakes Bioenergy Research Center and Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
| | - Bernardo Collao
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
| | - Paulina F Calderón
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
| | - Catalina A Chahuán
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
| | - Lillian G Acuña
- Laboratorio de Ecofisiología Microbiana, Fundación Ciencia & Vida, Santiago, Chile.
| | - Fernando Gil
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
| | - Claudia P Saavedra
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
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84
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Abstract
The activities of DNA methyltransferases are important for a variety of cellular functions in bacteria. In this study, we developed a modified high-throughput technique called methyl homopolymer tail mediated sequencing (methyl HTM-seq) to identify the undermethylated sites in the Vibrio cholerae genome for the two DNA methyltransferases, Dam, an adenine methyltransferase, and VchM, a cytosine methyltransferase, during growth in rich medium in vitro. Many of the undermethylated sites occurred in intergenic regions, and for most of these sites, we identified the transcription factors responsible for undermethylation. This confirmed the presence of previously hypothesized DNA-protein interactions for these transcription factors and provided insight into the biological state of these cells during growth in vitro. DNA adenine methylation has previously been shown to mediate heritable epigenetic switches in gene regulation. However, none of the undermethylated Dam sites tested showed evidence of regulation by this mechanism. This study is the first to identify undermethylated adenines and cytosines genomewide in a bacterium using second-generation sequencing technology.
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85
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Andrews S, Norton I, Salunkhe AS, Goodluck H, Aly WSM, Mourad-Agha H, Cornelis P. Control of iron metabolism in bacteria. Met Ions Life Sci 2013; 12:203-39. [PMID: 23595674 DOI: 10.1007/978-94-007-5561-1_7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bacteria depend upon iron as a vital cofactor that enables a wide range of key metabolic activities. Bacteria must therefore ensure a balanced supply of this essential metal. To do so, they invest considerable resourse into its acquisition and employ elaborate control mechanisms to eleviate both iron-induced toxitiy as well as iron deficiency. This chapter describes the processes that bacteria engage in maintaining iron homeostasis. The focus is Escherichia coli, as this bacterium provides a well studied example. A summary of the current status of understanding of iron management at the 'omics' level is also presented.
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Affiliation(s)
- Simon Andrews
- The School of Biological Sciences, The University of Reading, Whiteknights, Reading, RG6 6AJ, UK,
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86
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Zhang L, Xie J, Patel M, Bakhtyar A, Ehrlich GD, Ahmed A, Earl J, Marrs CF, Clemans D, Murphy TF, Gilsdorf JR. Nontypeable Haemophilus influenzae genetic islands associated with chronic pulmonary infection. PLoS One 2012; 7:e44730. [PMID: 22970300 PMCID: PMC3435294 DOI: 10.1371/journal.pone.0044730] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/07/2012] [Indexed: 11/19/2022] Open
Abstract
Background Haemophilus influenzae (Hi) colonizes the human respiratory tract and is an important pathogen associated with chronic obstructive pulmonary disease (COPD). Bacterial factors that interact with the human host may be important in the pathogenesis of COPD. These factors, however, have not been well defined. The overall goal of this study was to identify bacterial genetic elements with increased prevalence among H. influenzae strains isolated from patients with COPD compared to those isolated from the pharynges of healthy individuals. Methodology/Principal Findings Four nontypeable H. influenzae (NTHi) strains, two isolated from the airways of patients with COPD and two from a healthy individual, were subjected to whole genome sequencing using 454 FLX Titanium technology. COPD strain-specific genetic islands greater than 500 bp in size were identified by in silico subtraction. Open reading frames residing within these islands include known Hi virulence genes such as lic2b, hgbA, iga, hmw1 and hmw2, as well as genes encoding urease and other enzymes involving metabolic pathways. The distributions of seven selected genetic islands were assessed among a panel of 421 NTHi strains of both disease and commensal origins using a Library-on-a-Slide high throughput dot blot DNA hybridization procedure. Four of the seven islands screened, containing genes that encode a methyltransferase, a dehydrogenase, a urease synthesis enzyme, and a set of unknown short ORFs, respectively, were more prevalent in COPD strains than in colonizing strains with prevalence ratios ranging from 1.21 to 2.85 (p≤0.0002). Surprisingly, none of these sequences show increased prevalence among NTHi isolated from the airways of patients with cystic fibrosis. Conclusions/Significance Our data suggest that specific bacterial genes, many involved in metabolic functions, are associated with the ability of NTHi strains to survive in the lower airways of patients with COPD.
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Affiliation(s)
- Lixin Zhang
- Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, Michigan, United States of America.
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87
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OxyR activation in Porphyromonas gingivalis in response to a hemin-limited environment. Infect Immun 2012; 80:3471-80. [PMID: 22825453 DOI: 10.1128/iai.00680-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis is a Gram-negative obligately anaerobic bacterium associated with several forms of periodontal disease, most closely with chronic periodontitis. Previous studies demonstrated that OxyR plays an important role in the aerotolerance of P. gingivalis by upregulating the expression of oxidative-stress genes. Increases in oxygen tension and in H(2)O(2) both induce activation of OxyR. It is also known that P. gingivalis requires hemin as an iron source for its growth. In this study, we found that a hemin-limited growth environment significantly enhanced OxyR activity in P. gingivalis. As a result, expression of sod, dps, and ahpC was also upregulated. Using a chromatin immunoprecipitation quantitative PCR (qPCR) analysis, DNA binding of activated OxyR to the promoter of the sod gene was enhanced in P. gingivalis grown under hemin-limited conditions compared to excess-hemin conditions. Cellular tolerance of H(2)O(2) was also enhanced when hemin was limited in the growth medium of P. gingivalis. Our work supports a model in which hemin serves as a signal for the regulation of OxyR activity and indicates that P. gingivalis coordinately regulates expression of oxidative-stress-related genes by this hemin concentration-dependent pathway.
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88
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A ferritin mutant of Mycobacterium tuberculosis is highly susceptible to killing by antibiotics and is unable to establish a chronic infection in mice. Infect Immun 2012; 80:3650-9. [PMID: 22802345 DOI: 10.1128/iai.00229-12] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Iron is an essential, elusive, and potentially toxic nutrient for most pathogens, including Mycobacterium tuberculosis. Due to the poor solubility of ferric iron under aerobic conditions, free iron is not found in the host. M. tuberculosis requires specialized iron acquisition systems to replicate and cause disease. It also depends on a strict control of iron metabolism and intracellular iron levels to prevent iron-mediated toxicity. Under conditions of iron sufficiency, M. tuberculosis represses iron acquisition and induces iron storage, suggesting an important role for iron storage proteins in iron homeostasis. M. tuberculosis synthesizes two iron storage proteins, a ferritin (BfrB) and a bacterioferritin (BfrA). The individual contributions of these proteins to the adaptive response of M. tuberculosis to changes in iron availability are not clear. By generating individual knockout strains of bfrA and bfrB, the contribution of each one of these proteins to the maintenance of iron homeostasis was determined. The effect of altered iron homeostasis, resulting from impaired iron storage, on the resistance of M. tuberculosis to in vitro and in vivo stresses was examined. The results show that ferritin is required to maintain iron homeostasis, whereas bacterioferritin seems to be dispensable for this function. M. tuberculosis lacking ferritin suffers from iron-mediated toxicity, is unable to persist in mice, and, most importantly, is highly susceptible to killing by antibiotics, showing that endogenous oxidative stress can enhance the antibiotic killing of this important pathogen. These results are relevant for the design of new therapeutic strategies against M. tuberculosis.
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89
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Abstract
Dps proteins are the structural relatives of bacterioferritins and ferritins ubiquitously present in the bacterial and archaeal kingdoms. The ball-shaped enzymes play important roles in the detoxification of ROS (reactive oxygen species), in iron scavenging to prevent Fenton reactions and in the mechanical protection of DNA. Detoxification of ROS and iron chaperoning represent the most archetypical functions of dodecameric Dps enzymes. Recent crystallographic studies of these dodecameric complexes have unravelled species-dependent mechanisms of iron uptake into the hollow spheres. Subsequent functions in iron oxidation at ferroxidase centres are highly conserved among bacteria. Final nucleation of iron as iron oxide nanoparticles has been demonstrated to originate at acidic residues located on the inner surface. Some Dps enzymes are also implicated in newly observed catalytic functions related to the formation of molecules playing roles in bacterium–host cell communication. Most recently, Dps complexes are attracting attention in semiconductor science as biomimetic tools for the technical production of the smallest metal-based quantum nanodots used in nanotechnological approaches, such as memory storage or solar cell development.
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90
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Iron regulates expression of Bacillus cereus hemolysin II via global regulator Fur. J Bacteriol 2012; 194:3327-35. [PMID: 22522892 DOI: 10.1128/jb.00199-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The capacity of pathogens to respond to environmental signals, such as iron concentration, is key to bacterial survival and establishment of a successful infection. Bacillus cereus is a widely distributed bacterium with distinct pathogenic properties. Hemolysin II (HlyII) is one of its pore-forming cytotoxins and has been shown to be involved in bacterial pathogenicity in a number of cell and animal models. Unlike many other B. cereus pathogenicity factors, HlyII is not regulated by pleiotropic transcriptional regulator PlcR but is controlled by its own regulator, HlyIIR. Using a combination of in vivo and in vitro techniques, we show that hlyII expression is also negatively regulated by iron by the global regulator Fur via direct interaction with the hlyII promoter. DNase I footprinting and in vitro transcription experiments indicate that Fur prevents RNA polymerase binding to the hlyII promoter. HlyII expression profiles demonstrate that both HlyIIR and Fur regulate HlyII expression in a concerted fashion, with the effect of Fur being maximal in the early stages of bacterial growth. In sum, these results show that Fur serves as a transcriptional repressor for hlyII expression.
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91
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The FsrA sRNA and FbpB protein mediate the iron-dependent induction of the Bacillus subtilis lutABC iron-sulfur-containing oxidases. J Bacteriol 2012; 194:2586-93. [PMID: 22427629 DOI: 10.1128/jb.05567-11] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Bacillus subtilis ferric uptake regulator (Fur) protein regulates iron homeostasis and directly represses more than 20 operons. Fur indirectly regulates many more genes, including those controlled by the small, noncoding RNA FsrA. FsrA translationally represses numerous target genes and, for at least some targets, appears to function in conjunction with one or more of three small, basic proteins, known as FbpA, FbpB, and FbpC. The lactate-inducible lutABC operon encodes iron sulfur-containing enzymes required for growth on lactate. We here demonstrate that a fur mutant strain grows poorly on lactate due to FsrA-dependent repression of LutABC synthesis. Growth is restored in an fsrA mutant and also partially restored by mutation of the fbpAB operon. Genetic studies indicate that the 48-amino-acid FbpB protein but not FbpA contributes to regulation of lutABC. FbpB may function, at least in part, by increasing the efficiency of FsrA targeting to the lutABC mRNA, since the role of FbpB can be bypassed by modest upregulation of FsrA. These results provide support for a model in which FbpB, and perhaps other Fbp proteins, contributes along with FsrA to the translational regulation of gene expression.
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92
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Holden KM, Browning GF, Noormohammadi AH, Markham PF, Marenda MS. TonB is essential for virulence in avian pathogenic Escherichia coli. Comp Immunol Microbiol Infect Dis 2012; 35:129-38. [DOI: 10.1016/j.cimid.2011.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 11/25/2022]
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93
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Ruangkiattikul N, Bhubhanil S, Chamsing J, Niamyim P, Sukchawalit R, Mongkolsuk S. Agrobacterium tumefaciens membrane-bound ferritin plays a role in protection against hydrogen peroxide toxicity and is negatively regulated by the iron response regulator. FEMS Microbiol Lett 2012; 329:87-92. [PMID: 22268462 DOI: 10.1111/j.1574-6968.2012.02509.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Revised: 01/12/2012] [Accepted: 01/12/2012] [Indexed: 11/29/2022] Open
Abstract
An Agrobacterium tumefaciens membrane-bound ferritin (mbfA) mutant was generated to assess the physiological functions of mbfA in response to iron and hydrogen peroxide (H(2) O(2) ) stresses. Wild-type and the mbfA mutant strains showed similar growth under high- and low-iron conditions. The mbfA mutant was more sensitive to H(2) O(2) than wild-type strain. Expression of a functional mbfA gene could complement the H(2) O(2) -hypersensitive phenotype of the mbfA mutant and a rhizobial iron regulator (rirA) mutant, suggesting that MbfA protects cells from H(2) O(2) toxicity by sequestering intracellular free iron, thus preventing the Fenton reaction. The expression of mbfA could be induced in response to iron and to H(2) O(2) treatment. The iron response regulator (irr) also acted as a repressor of mbfA expression. An irr mutant had high constitutive expression of mbfA, which partly contributed to the H(2) O(2) -hyperresistant phenotype of the irr mutant. The data reported here demonstrate an important role of A. tumefaciens MbfA in the cellular defence against iron and H(2) O(2) stresses.
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94
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Miller MC, DeMoll E. Extraction, purification, and identification of yersiniabactin, the siderophore of Yersinia pestis. ACTA ACUST UNITED AC 2012; Chapter 5:Unit5B.3. [PMID: 22045585 DOI: 10.1002/9780471729259.mc05b03s23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This unit describes in detail the extraction, purification, and identification of Yersiniabactin the siderophore of Yersinia pestis. Iron is essential for bacterial growth. Although relatively abundant, access to iron is limited in nature by low solubility. This problem is exacerbated for pathogenic bacteria, which must also defeat the host organism's innate defenses, including mechanisms to sequester iron. One solution to these problems is production of water soluble, small molecules with high affinities for iron called siderophores. This protocol has been fine tuned for Yersiniabactin purification but may be easily modified for use in isolating other siderophores or similar molecules.
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Affiliation(s)
- M Clarke Miller
- James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, USA
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95
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Merchant SS, Helmann JD. Elemental economy: microbial strategies for optimizing growth in the face of nutrient limitation. Adv Microb Physiol 2012; 60:91-210. [PMID: 22633059 PMCID: PMC4100946 DOI: 10.1016/b978-0-12-398264-3.00002-4] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility for fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Despite their prodigious capacity for molecular transformations, microorganisms are powerless in the face of the immutability of the elements. Limitations for specific elements, either fleeting or persisting over eons, have left an indelible trace on microbial genomes, physiology, and their very atomic composition. We here review the impact of elemental limitation on microbes, with a focus on selected genetic model systems and representative microbes from the ocean ecosystem. Evolutionary adaptations that enhance growth in the face of persistent or recurrent elemental limitations are evident from genome and proteome analyses. These range from the extreme (such as dispensing with a requirement for a hard to obtain element) to the extremely subtle (changes in protein amino acid sequences that slightly, but significantly, reduce cellular carbon, nitrogen, or sulfur demand). One near-universal adaptation is the development of sophisticated acclimation programs by which cells adjust their chemical composition in response to a changing environment. When specific elements become limiting, acclimation typically begins with an increased commitment to acquisition and a concomitant mobilization of stored resources. If elemental limitation persists, the cell implements austerity measures including elemental sparing and elemental recycling. Insights into these fundamental cellular properties have emerged from studies at many different levels, including ecology, biological oceanography, biogeochemistry, molecular genetics, genomics, and microbial physiology. Here, we present a synthesis of these diverse studies and attempt to discern some overarching themes.
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Affiliation(s)
- Sabeeha S. Merchant
- Institute for Genomics and Proteomics and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, NY, 14853-8101
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96
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Iron storage proteins are essential for the survival and pathogenesis of Mycobacterium tuberculosis in THP-1 macrophages and the guinea pig model of infection. J Bacteriol 2011; 194:567-75. [PMID: 22101841 DOI: 10.1128/jb.05553-11] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Iron is one of the crucial elements required for the growth of Mycobacterium tuberculosis. However, excess free iron becomes toxic for the cells because it catalyzes the production of reactive oxygen radicals, leading to oxidative damage. Hence, it is essential for the pathogen to have the ability to store intracellular iron in an iron-rich environment and utilize it under iron depletion. M. tuberculosis has two iron storage proteins, namely BfrA (Rv1876; a bacterioferritin) and BfrB (Rv3841; a ferritin-like protein). However, the demonstration of biological significance requires the disruption of relevant genes and the evaluation of the resulting mutant for its ability to survive in the host and cause disease. In this study, we have disrupted bfrA and bfrB of M. tuberculosis and demonstrated that these genes are crucial for the storage and supply of iron for the growth of bacteria and to withstand oxidative stress in vitro. In addition, the bfrA bfrB double mutant (H37Rv ΔbfrA ΔbfrB) exhibited a marked reduction in its ability to survive inside human macrophages. Guinea pigs infected with H37Rv ΔbfrA ΔbfrB exhibited a marked diminution in the dissemination of the bacilli to spleen compared to that of the parental strain. Moreover, guinea pigs infected with H37Rv ΔbfrA ΔbfrB exhibited significantly reduced pathological damage in spleen and lungs compared to that of animals infected with the parental strain. Our study clearly demonstrates the importance of these iron storage proteins in the survival and pathogenesis of M. tuberculosis in the host and establishes them as attractive targets for the development of new inhibitors against mycobacterial infections.
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97
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Cornelis P, Wei Q, Andrews SC, Vinckx T. Iron homeostasis and management of oxidative stress response in bacteria. Metallomics 2011; 3:540-9. [PMID: 21566833 DOI: 10.1039/c1mt00022e] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Iron is both an essential nutrient for the growth of microorganisms, as well as a dangerous metal due to its capacity to generate reactive oxygen species (ROS) via the Fenton reaction. For these reasons, bacteria must tightly control the uptake and storage of iron in a manner that restricts the build-up of ROS. Therefore, it is not surprising to find that the control of iron homeostasis and responses to oxidative stress are coordinated. The mechanisms concerned with these processes, and the interactions involved, are the subject of this review.
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Affiliation(s)
- Pierre Cornelis
- Microbial Interactions, Department of Molecular and Cellular Interactions, VIB and Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
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98
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Gilbreath JJ, Cody WL, Merrell DS, Hendrixson DR. Change is good: variations in common biological mechanisms in the epsilonproteobacterial genera Campylobacter and Helicobacter. Microbiol Mol Biol Rev 2011; 75:84-132. [PMID: 21372321 PMCID: PMC3063351 DOI: 10.1128/mmbr.00035-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Microbial evolution and subsequent species diversification enable bacterial organisms to perform common biological processes by a variety of means. The epsilonproteobacteria are a diverse class of prokaryotes that thrive in diverse habitats. Many of these environmental niches are labeled as extreme, whereas other niches include various sites within human, animal, and insect hosts. Some epsilonproteobacteria, such as Campylobacter jejuni and Helicobacter pylori, are common pathogens of humans that inhabit specific regions of the gastrointestinal tract. As such, the biological processes of pathogenic Campylobacter and Helicobacter spp. are often modeled after those of common enteric pathogens such as Salmonella spp. and Escherichia coli. While many exquisite biological mechanisms involving biochemical processes, genetic regulatory pathways, and pathogenesis of disease have been elucidated from studies of Salmonella spp. and E. coli, these paradigms often do not apply to the same processes in the epsilonproteobacteria. Instead, these bacteria often display extensive variation in common biological mechanisms relative to those of other prototypical bacteria. In this review, five biological processes of commonly studied model bacterial species are compared to those of the epsilonproteobacteria C. jejuni and H. pylori. Distinct differences in the processes of flagellar biosynthesis, DNA uptake and recombination, iron homeostasis, interaction with epithelial cells, and protein glycosylation are highlighted. Collectively, these studies support a broader view of the vast repertoire of biological mechanisms employed by bacteria and suggest that future studies of the epsilonproteobacteria will continue to provide novel and interesting information regarding prokaryotic cellular biology.
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Affiliation(s)
- Jeremy J. Gilbreath
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - William L. Cody
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - D. Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - David R. Hendrixson
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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Vajrala N, Sayavedra-Soto LA, Bottomley PJ, Arp DJ. Role of a Fur homolog in iron metabolism in Nitrosomonas europaea. BMC Microbiol 2011; 11:37. [PMID: 21338516 PMCID: PMC3050691 DOI: 10.1186/1471-2180-11-37] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 02/21/2011] [Indexed: 11/24/2022] Open
Abstract
Background In response to environmental iron concentrations, many bacteria coordinately regulate transcription of genes involved in iron acquisition via the ferric uptake regulation (Fur) system. The genome of Nitrosomonas europaea, an ammonia-oxidizing bacterium, carries three genes (NE0616, NE0730 and NE1722) encoding proteins belonging to Fur family. Results Of the three N. europaea fur homologs, only the Fur homolog encoded by gene NE0616 complemented the Escherichia coli H1780 fur mutant. A N. europaea fur:kanP mutant strain was created by insertion of kanamycin-resistance cassette in the promoter region of NE0616 fur homolog. The total cellular iron contents of the fur:kanP mutant strain increased by 1.5-fold compared to wild type when grown in Fe-replete media. Relative to the wild type, the fur:kanP mutant exhibited increased sensitivity to iron at or above 500 μM concentrations. Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability. Conclusions Our studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene. Additional studies are required to fully delineate role of this fur homolog.
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Affiliation(s)
- Neeraja Vajrala
- Department of Botany and Plant Pathology, 2082 Cordley, Oregon State University, Corvallis, OR 97331, USA
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100
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A Ferritin-Based Label for Cellular Electron Cryotomography. Structure 2011; 19:147-54. [DOI: 10.1016/j.str.2010.12.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 12/06/2010] [Accepted: 12/10/2010] [Indexed: 11/17/2022]
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