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Alternative σ Factors Regulate Overlapping as Well as Distinct Stress Response and Metabolic Functions in Listeria monocytogenes under Stationary Phase Stress Condition. Pathogens 2021; 10:pathogens10040411. [PMID: 33915780 PMCID: PMC8066629 DOI: 10.3390/pathogens10040411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 12/13/2022] Open
Abstract
Listeria monocytogenes can regulate and fine-tune gene expression, to adapt to diverse stress conditions encountered during foodborne transmission. To further understand the contributions of alternative sigma (σ) factors to the regulation of L. monocytogenes gene expression, RNA-Seq was performed on L. monocytogenes strain 10403S and five isogenic mutants (four strains bearing in-frame null mutations in three out of four alternative σ factor genes, ΔCHL, ΔBHL, ΔBCL, and ΔBCH, and one strain bearing null mutations in all four genes, ΔBCHL), grown to stationary phase. Our data showed that 184, 35, 34, and 20 genes were positively regulated by σB, σL, σH, and σC (posterior probability > 0.9 and Fold Change (FC) > 5.0), respectively. Moreover, σB-dependent genes showed the highest FC (based on comparisons between the ΔCHL and the ΔBCHL strain), with 44 genes showing an FC > 100; only four σL-dependent, and no σH- or σC-dependent genes showed FC >100. While σB-regulated genes identified in this study are involved in stress-associated functions and metabolic pathways, σL appears to largely regulate genes involved in a few specific metabolic pathways, including positive regulation of operons encoding phosphoenolpyruvate (PEP)-dependent phosphotransferase systems (PTSs). Overall, our data show that (i) σB and σL directly and indirectly regulate genes involved in several energy metabolism-related functions; (ii) alternative σ factors are involved in complex regulatory networks and appear to have epistatic effects in stationary phase cells; and (iii) σB regulates multiple stress response pathways, while σL and σH positively regulate a smaller number of specific pathways.
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Kang S, Meng Y, Cheng X, Tu J, Guo D, Xu Y, Liang S, Xia X, Shi C. Effects of 405-nm LED Treatment on the Resistance of Listeria monocytogenes to Subsequent Environmental Stresses. Front Microbiol 2019; 10:1907. [PMID: 31474971 PMCID: PMC6706791 DOI: 10.3389/fmicb.2019.01907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 08/05/2019] [Indexed: 11/13/2022] Open
Abstract
Listeria monocytogenes can persist under a wide range of stress conditions, contributing to its ubiquitous distribution and unique pathogenic traits. Light from light-emitting diodes (LEDs) has recently been shown to inactivate various pathogens. Thus, the aim of the present study was to evaluate the effects of light treatment using a 405-nm LED on the subsequent resistance of L. monocytogenes to environmental stresses, including oxidative stress, ultraviolet (UV) irradiation, low temperature, osmotic pressure, simulated gastric fluid (SGF), and bile salts. Following 405-nm LED illumination at 4°C for 150 min, the survival of L. monocytogenes was examined after exposure to oxidative stress (0.04% H2O2), UV irradiation (253.7 nm), low temperature (4°C), osmotic pressure (10, 15, or 20% NaCl), SGF (pH 2.5), or bile salts (2%). The mechanisms responsible for changes in stress tolerance were identified by assessing the transcriptional responses and membrane integrity of L. monocytogenes. The 405-nm LED treatment reduced the resistance of L. monocytogenes to all the stresses tested. Reverse transcription quantitative real-time polymerase chain reaction analysis indicated that the transcription of multiple genes associated with stress resistance, including betL, gbuA, oppA, fri, bsh, and arcA, was reduced by 405-nm LED. Confocal laser scanning microscopy revealed that 405-nm LED treatment disrupted the integrity of the L. monocytogenes cell membrane compared with untreated bacteria. Therefore, 405-nm LED illumination appears to reduce the resistance of L. monocytogenes to various stress conditions. These findings suggest that 405-nm LED treatment could be used to effectively prevent and/or control with L. monocytogenes contamination along the entire food-processing chain, from production to consumption.
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Affiliation(s)
- Shenmin Kang
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Yujie Meng
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Xiaomeng Cheng
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Junhong Tu
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Du Guo
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Yunfeng Xu
- College of Food and Bioengineering, Henan University of Science and Technology, Luoyang, China
| | - Sen Liang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China
| | - Xiaodong Xia
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Chao Shi
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
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Cufaoglu G, Ayaz ND. Listeria monocytogenesrisk associated with chicken at slaughter and biocontrol with three new bacteriophages. J Food Saf 2019. [DOI: 10.1111/jfs.12621] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gizem Cufaoglu
- Department of Food Hygiene and TechnologyKirikkale University Faculty of Veterinary Medicine Yahsihan Kirikkale Turkey
| | - Naim Deniz Ayaz
- Department of Food Hygiene and TechnologyKirikkale University Faculty of Veterinary Medicine Yahsihan Kirikkale Turkey
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Dos Santos PT, Larsen PT, Menendez-Gil P, Lillebæk EMS, Kallipolitis BH. Listeria monocytogenes Relies on the Heme-Regulated Transporter hrtAB to Resist Heme Toxicity and Uses Heme as a Signal to Induce Transcription of lmo1634, Encoding Listeria Adhesion Protein. Front Microbiol 2018; 9:3090. [PMID: 30619169 PMCID: PMC6305404 DOI: 10.3389/fmicb.2018.03090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/29/2018] [Indexed: 01/29/2023] Open
Abstract
For pathogenic bacteria, host-derived heme represents an important metabolic cofactor and a source for iron. However, high levels of heme are toxic to bacteria. We have previously shown that excess heme has a growth-inhibitory effect on the Gram-positive foodborne pathogen Listeria monocytogenes, and we have learned that the LhrC1-5 family of small RNAs, together with the two-component system (TCS) LisRK, play a role in the adaptation of L. monocytogenes to heme stress conditions. However, a broader knowledge on how this pathogen responds to heme toxicity is still lacking. Here, we analyzed the global transcriptomic response of L. monocytogenes to heme stress. We found that the response of L. monocytogenes to excess heme is multifaceted, involving various strategies acting to minimize the toxic effects of heme. For example, heme exposure triggers the SOS response that deals with DNA damage. In parallel, L. monocytogenes shuts down the transcription of genes involved in heme/iron uptake and utilization. Furthermore, heme stress resulted in a massive increase in the transcription of a putative heme detoxification system, hrtAB, which is highly conserved in Gram-positive bacteria. As expected, we found that the TCS HssRS is required for heme-mediated induction of hrtAB and that a functional heme efflux system is essential for L. monocytogenes to resist heme toxicity. Curiously, the most highly up-regulated gene upon heme stress was lmo1634, encoding the Listeria adhesion protein, LAP, which acts to promote the translocation of L. monocytogenes across the intestinal barrier. Additionally, LAP is predicted to act as a bifunctional acetaldehyde-CoA/alcohol dehydrogenase. Surprisingly, a mutant lacking lmo1634 grows well under heme stress conditions, showing that LAP is not required for L. monocytogenes to resist heme toxicity. Likewise, a functional ResDE TCS, which contributes to heme-mediated expression of lmo1634, is not required for the adaptation of L. monocytogenes to heme stress conditions. Collectively, this study provides novel insights into the strategies employed by L. monocytogenes to resist heme toxicity. Our findings indicate that L. monocytogenes is using heme as a host-derived signaling molecule to control the expression of its virulence genes, as exemplified by lmo1634.
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Affiliation(s)
| | - Pernille Tholund Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Pilar Menendez-Gil
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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Ayaz ND, Onaran B, Cufaoglu G, Goncuoglu M, Ormanci FS, Erol I. Prevalence and Characterization of Listeria monocytogenes Isolated from Beef and Sheep Carcasses in Turkey with Characterization of Locally Isolated Listeriophages as a Control Measure. J Food Prot 2018; 81:2045-2053. [PMID: 30485766 DOI: 10.4315/0362-028x.jfp-18-310] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Swab samples from cattle and sheep carcasses (120 of each) were tested for Listeria monocytogenes, and 120 slaughterhouse wastewater samples were tested for listeriophages over 12 months (10 samples per month) to note the seasonal distribution. L. monocytogenes and bacteriophage isolates were characterized, and the biocontrol of L. monocytogenes was investigated in meatballs with a phage cocktail. L. monocytogenes was found in 3.4 and 2.5% of cattle and sheep carcasses, respectively. All the isolates were found to harbor hlyA, actA, inlA, inlB, inlC, inlJ, plcA, plcB, fbpA, and fri genes with varied mRNA expression levels by real-time reverse transcriptase PCR analysis. Five isolates did not harbor the vip gene. According to enterobacterial repetitive intergenic consensus PCR, L. monocytogenes isolates were classified into four different groups based on their DNA patterns. The L. monocytogenes isolates were characterized for antibiotic susceptibility; one strain was found to be resistant to five different antibiotic classes. Of 11 lytic listeriophages, two were selected for the cocktail based on their DNA restriction profiles, efficiency of plating, transmission electron microscopy, and in vitro and in vivo analyses. In the biocontrol study, we used a food model that consisted of a novel bacteriophage cocktail in raw meatballs. The highest reduction of L. monocytogenes was recorded as 2.2 log CFU/g at a multiplicity of cellular infection of 4.7 at the end of 1 h. In conclusion, the new bacteriophage cocktail in this study can be considered an efficient biocontrol agent of L. monocytogenes in meatballs.
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Affiliation(s)
- Naim Deniz Ayaz
- 1 Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Kirikkale University, 71450 Yahsihan, Kirikkale, Turkey
| | - Bahar Onaran
- 2 Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ankara University, 06110 Diskapi, Ankara, Turkey
| | - Gizem Cufaoglu
- 1 Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Kirikkale University, 71450 Yahsihan, Kirikkale, Turkey
| | - Muammer Goncuoglu
- 2 Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ankara University, 06110 Diskapi, Ankara, Turkey
| | - Fatma Seda Ormanci
- 2 Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ankara University, 06110 Diskapi, Ankara, Turkey
| | - Irfan Erol
- 3 General Directorate of Food and Control, Republic of Turkey Ministry of Food Agriculture and Livestock, 06400 Lodumlu, Ankara, Turkey
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Sarvan S, Butcher J, Stintzi A, Couture JF. Variation on a theme: investigating the structural repertoires used by ferric uptake regulators to control gene expression. Biometals 2018; 31:681-704. [DOI: 10.1007/s10534-018-0120-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 11/29/2022]
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Majou D, Christieans S. Mechanisms of the bactericidal effects of nitrate and nitrite in cured meats. Meat Sci 2018; 145:273-284. [PMID: 30005374 DOI: 10.1016/j.meatsci.2018.06.013] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 06/12/2018] [Accepted: 06/12/2018] [Indexed: 12/20/2022]
Abstract
For cured meat products, nitrite is recognized for its antimicrobial effects against pathogenic bacteria, even though the specific inhibitory mechanisms are not well known. Nitrite contributes to oxidative stress by being the precursor of peroxynitrite (ONOO-), which is the major strong oxidant. Thus, bacterial stress (highly pH-very low partial pressure of oxygen-dependent) is enhanced by the nitrate-nitrite-peroxynitrite system which is also highly pH- and low partial pressure of oxygen-dependent. Nitrite is a hurdle technology which effectiveness depends on several other hurdle technologies including sodium chloride (accelerating the autoxidation of oxymyoglobin and promote peroxynitrite formation), ascorbate (increasing ONOO- synthesis), and Aw. In this environment, certain species are more resistant than others to acidic, oxidative, and nitrative stresses. The most resistant are gram-negative aerobic/facultative anaerobic bacteria (Escherichia coli, Salmonella), and the most fragile are gram-positive anaerobic bacteria (Clostridium botulinum). This position review highlights the major chemical mechanisms involved, the active molecules and their actions on bacterial metabolisms in the meat ecosystem.
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Affiliation(s)
- Didier Majou
- Association pour la Coordination Technique pour l'Industrie Agro-Alimentaire (ACTIA), 16, rue Claude Bernard, 75005 Paris 05, France
| | - Souad Christieans
- Association pour le Développement de l'Industrie de la Viande (ADIV), 10, rue Jacqueline Auriol, 63039 Clermont-Ferrand, France..
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Comparison of oxidative stress response and biofilm formation of Listeria monocytogenes serotypes 4b and 1/2a. Food Control 2018. [DOI: 10.1016/j.foodcont.2017.10.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Pieta L, Escudero FLG, Jacobus AP, Cheiran KP, Gross J, Moya MLE, Soares GLG, Margis R, Frazzon APG, Frazzon J. Comparative transcriptomic analysis of Listeria monocytogenes reveals upregulation of stress genes and downregulation of virulence genes in response to essential oil extracted from Baccharis psiadioides. ANN MICROBIOL 2017. [DOI: 10.1007/s13213-017-1277-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Botello-Morte L, Pellicer S, Sein-Echaluce VC, Contreras LM, Neira JL, Abián O, Velázquez-Campoy A, Peleato ML, Fillat MF, Bes MT. Cysteine Mutational Studies Provide Insight into a Thiol-Based Redox Switch Mechanism of Metal and DNA Binding in FurA from Anabaena sp. PCC 7120. Antioxid Redox Signal 2016; 24:173-185. [PMID: 26414804 PMCID: PMC4744886 DOI: 10.1089/ars.2014.6175] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AIMS The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron homeostasis in most prokaryotes. FurA from Anabaena sp. PCC 7120 contains five cysteine residues, four of them arranged in two redox-active CXXC motifs. The protein needs not only metal but also reducing conditions to remain fully active in vitro. Through a mutational study of the cysteine residues present in FurA, we have investigated their involvement in metal and DNA binding. RESULTS Residue C101 that belongs to a conserved CXXC motif plays an essential role in both metal and DNA binding activities in vitro. Substitution of C101 by serine impairs DNA and metal binding abilities of FurA. Isothermal titration calorimetry measurements show that the redox state of C101 is responsible for the protein ability to coordinate the metal corepressor. Moreover, the redox state of C101 varies with the presence or absence of C104 or C133, suggesting that the environments of these cysteines are mutually interdependent. INNOVATION We propose that C101 is part of a thiol/disulfide redox switch that determines FurA ability to bind the metal corepressor. CONCLUSION This mechanism supports a novel feature of a Fur protein that emerges as a regulator, which connects the response to changes in the intracellular redox state and iron management in cyanobacteria. Antioxid. Redox Signal. 00, 000-000.
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Affiliation(s)
- Laura Botello-Morte
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain
| | - Silvia Pellicer
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain
| | - Violeta C Sein-Echaluce
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain
| | - Lellys M Contreras
- 3 Institut of Molecular and Cellular Biology, Miguel Hernández University of Elche , Elche, Spain
| | - José Luis Neira
- 2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .,3 Institut of Molecular and Cellular Biology, Miguel Hernández University of Elche , Elche, Spain
| | - Olga Abián
- 2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .,4 IIS Aragon-Aragon Health Science Institute (IACS) and Networked Biomedical Research Center of Hepatic and Digestive Diseases (CIBERehd) , Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .,5 ARAID Foundation , Government of Aragón, Zaragoza, Spain
| | - María Luisa Peleato
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain
| | - María F Fillat
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain
| | - María Teresa Bes
- 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .,2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain
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Nowak J, Cruz CD, Palmer J, Fletcher GC, Flint S. Biofilm formation of the L. monocytogenes strain 15G01 is influenced by changes in environmental conditions. J Microbiol Methods 2015; 119:189-95. [PMID: 26524221 DOI: 10.1016/j.mimet.2015.10.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/27/2015] [Accepted: 10/28/2015] [Indexed: 02/06/2023]
Abstract
Listeria monocytogenes 15G01, a strain belonging to the persistent pulsotype 5132, was isolated from a seafood processing plant in New Zealand. Simple monoculture assays using crystal violet staining showed good biofilm formation for this strain and it was therefore chosen to be further investigated in regard to its biofilm forming ability. To evaluate its behaviour in different conditions commonly encountered in food processing environments, biofilm assays and growth studies were performed using common laboratory media under a range of temperatures (20 °C, 30 °C and 37 °C). Furthermore, the effects of incubation time and different environmental conditions including static, dynamic and anaerobic incubation on biofilm formation were investigated. Changes in the environmental conditions resulted in different biofilm phenotypes of L. monocytogenes 15G01. We demonstrated that increasing temperature and incubation time led to a higher biofilm mass and that dynamic incubation has little effect on biofilm formation at 37 °C but encourages biofilm formation at 30 °C. Biofilm production at 20 °C was minimal regardless of the medium used. We furthermore observed that anaerobic environment led to reduced biofilm mass at 30 °C for all tested media but not at 37 °C. Biofilm formation could not be narrowed down to one factor but was rather dependent on multiple factors with temperature and medium having the biggest effects.
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Affiliation(s)
- Jessika Nowak
- The New Zealand Institute for Plant & Food Research Limited, Mt Albert, Auckland, New Zealand; Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand.
| | - Cristina D Cruz
- The New Zealand Institute for Plant & Food Research Limited, Mt Albert, Auckland, New Zealand
| | - Jon Palmer
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Graham C Fletcher
- The New Zealand Institute for Plant & Food Research Limited, Mt Albert, Auckland, New Zealand
| | - Steve Flint
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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Mata MM, da Silva WP, Wilson R, Lowe E, Bowman JP. Attached and planktonic Listeria monocytogenes global proteomic responses and associated influence of strain genetics and temperature. J Proteome Res 2015; 14:1161-73. [PMID: 25516393 DOI: 10.1021/pr501114e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Contamination of industrial and domestic food usage environments by the attachement of bacterial food-borne pathogen Listeria monocytogenes has public health and economic implications. Comprehensive proteomics experiments using label-free liquid chromatography/tandem mass spectrometry were used to compare the proteomes of two different L. monocytogenes strains (Siliken_1/2c and F2365_4b), which show very different capacities to attach to surfaces. Growth temperature and strain type were highly influential on the proteomes in both attached and planktonic cells. On the basis of the proteomic data, it is highly unlikely that specific surface proteins play a direct role in adherence to inanimate surfaces. Instead, strain-dependent responses related to cell envelope polymer biosynthesis and stress response regulation likely contribute to a different ability to attach and also to survive external stressors. Collectively, the divergent proteome-level responses observed define strain- and growth-temperature-dependent differences relevant to attachment efficacy, highlight relevant proteins involved in stress protection in attached cells, and suggest that strain differences and growth conditions are important in relation to environmental persistence.
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Affiliation(s)
- Marcia M Mata
- Science and Agroindustrial Technology Department, Federal University of Pelotas , Pelotas 96160-000, Brazil
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14
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Botello-Morte L, Bes MT, Heras B, Fernández-Otal Á, Peleato ML, Fillat MF. Unraveling the redox properties of the global regulator FurA from Anabaena sp. PCC 7120: disulfide reductase activity based on its CXXC motifs. Antioxid Redox Signal 2014; 20:1396-406. [PMID: 24093463 PMCID: PMC3936511 DOI: 10.1089/ars.2013.5376] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
UNLABELLED Cyanobacterial FurA works as a global regulator linking iron homeostasis to photosynthetic metabolism and the responses to different environmental stresses. Additionally, FurA modulates several genes involved in redox homeostasis and fulfills the characteristics of a heme-sensor protein whose interaction with this cofactor negatively affects its DNA binding ability. FurA from Anabaena PCC 7120 contains five cysteine residues, four of them arranged in two redox CXXC motifs. AIMS Our goals were to analyze in depth the putative contribution of these CXXC motifs in the redox properties of FurA and to identify potential interacting partners of this regulator. RESULTS Insulin reduction assays unravel that FurA exhibits disulfide reductase activity. Simultaneous presence of both CXXC signatures greatly enhances the reduction rate, although the redox motif containing Cys(101) and Cys(104) seems a major contributor to this activity. Disulfide reductase activity was not detected in other ferric uptake regulator (Fur) proteins isolated from heterotrophic bacteria. In vivo, FurA presents different redox states involving intramolecular disulfide bonds when is partially oxidized. Redox potential values for CXXC motifs, -235 and -238 mV, are consistent with those reported for other proteins displaying disulfide reductase activity. Pull-down and two-hybrid assays unveil potential FurA interacting partners, namely phosphoribulokinase Alr4123, the hypothetical amidase-containing domain All1140 and the DNA-binding protein HU. INNOVATION A novel biochemical activity of cyanobacterial FurA based on its cysteine arrangements and the identification of novel interacting partners are reported. CONCLUSION The present study discloses a putative connection of FurA with the cyanobacterial redox-signaling pathway.
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Affiliation(s)
- Laura Botello-Morte
- 1 Department of Biochemistry and Molecular and Cell Biology, Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza , Zaragoza, Spain
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Krawczyk-Balska A, Lipiak M. Critical role of a ferritin-like protein in the control of Listeria monocytogenes cell envelope structure and stability under β-lactam pressure. PLoS One 2013; 8:e77808. [PMID: 24204978 PMCID: PMC3812014 DOI: 10.1371/journal.pone.0077808] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 09/05/2013] [Indexed: 02/08/2023] Open
Abstract
The human pathogen Listeria monocytogenes is susceptible to the β-lactam antibiotics penicillin G and ampicillin, and these are the drugs of choice for the treatment of listerial infections. However, these antibiotics exert only a bacteriostatic effect on this bacterium and consequently, L. monocytogenes is regarded as β-lactam tolerant. It is widely accepted that the phenomenon of bacterial tolerance to β-lactams is due to the lack of adequate autolysin activity, but the mechanisms of L. monocytogenes tolerance to this class of antibiotics are poorly characterized. A ferritin-like protein (Fri) was recently identified as a mediator of β-lactam tolerance in L. monocytogenes, but its function in this process remains unknown. The present study was undertaken to improve our understanding of L. monocytogenes tolerance to β-lactams and to characterize the role of Fri in this phenomenon. A comparative physiological analysis of wild-type L. monocytogenes and a fri deletion mutant provided evidence of a multilevel mechanism controlling autolysin activity in cells grown under β-lactam pressure, which leads to a reduction in the level and/or activity of cell wall-associated autolysins. This is accompanied by increases in the amount of teichoic acids, cell wall thickness and cell envelope integrity of L. monocytogenes grown in the presence of penicillin G, and provides the basis for the innate β-lactam tolerance of this bacterium. Furthermore, this study revealed the inability of the L. monocytogenes Δ fri mutant to deplete autolysins from the cell wall, to adjust the content of teichoic acids and to maintain their D-alanylation at the correct level when treated with penicillin G, thus providing further evidence that Fri is involved in the control of L. monocytogenes cell envelope structure and stability under β-lactam pressure.
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Affiliation(s)
- Agata Krawczyk-Balska
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Magdalena Lipiak
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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Machado H, Lourenço A, Carvalho F, Cabanes D, Kallipolitis BH, Brito L. The Tat pathway is prevalent in Listeria monocytogenes lineage II and is not required for infection and spread in host cells. J Mol Microbiol Biotechnol 2013; 23:209-18. [PMID: 23595063 DOI: 10.1159/000348245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Listeria monocytogenes, a foodborne pathogenic bacterium, remains a serious public health concern due to its frequent occurrence in food products coupled with a high mortality rate. Bacterial pathogenicity depends greatly on the ability to secrete virulence factors to or beyond the bacterial cell surface. The Tat pathway, one of the secretion systems present in L. monocytogenes, was until now only investigated in silico. In L. monocytogenes strain EGDe two genes constitute this pathway, tatC(lmo0361) and tatA(lmo0362). Here we show that tatC and tatA are cotranscribed in a bicistronic- and growth-phase-dependent manner, being downregulated in the stationary phase. An EGDe tatAC mutant strain (EGDe ΔtatAC) was constructed, confirming that the Tat pathway is not essential for L.monocytogenes survival or biofilm-forming ability. When compared to the wild-type EGDe, deletion of tatAC did not decrease the virulence potential of EGDe ΔtatAC in HT-29 human epithelial cell line and even increased (p < 0.05) the virulence potential for mice. Moreover, we show that tat genes are prevalent in L. monocytogenes strains belonging to genetic lineage II and are generally absent from lineage I, which is more associated with human cases, thus excluding the possibility of using the Tat system as a target for novel antimicrobial compounds targeting L.monocytogenes.
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Affiliation(s)
- Henrique Machado
- CBAA/DRAT, Laboratório de Microbiologia, Instituto Superior de Agronomia, Technical University of Lisbon, Lisbon, Portugal
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17
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Ardini M, Fiorillo A, Fittipaldi M, Stefanini S, Gatteschi D, Ilari A, Chiancone E. Kineococcus radiotolerans Dps forms a heteronuclear Mn-Fe ferroxidase center that may explain the Mn-dependent protection against oxidative stress. Biochim Biophys Acta Gen Subj 2013; 1830:3745-55. [PMID: 23396000 DOI: 10.1016/j.bbagen.2013.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 01/14/2013] [Accepted: 02/04/2013] [Indexed: 01/30/2023]
Abstract
BACKGROUND The ferroxidase center of DNA-binding protein from starved cells (Dps) is a major player in the iron oxidation/detoxification process that leads to a decreased reactive oxygen species production. The possible Mn(II) participation in this process has been studied in Dps from Kineococcus radiotolerans, a radiation-resistant bacterium with a high cytosolic Mn/Fe ratio and a high capacity to survive ionizing and stress conditions. METHODS The X-ray structure of recombinant K. radiotolerans Dps loaded with Mn(II) has been solved at 2.0Å resolution. Mn(II) binding to K. radiotolerans Dps and its effect on Fe(II) oxidation have been characterized in spectroscopic measurements. RESULTS In K. radiotolerans Dps, the Fe-Fe ferroxidase center can have a Mn-Fe composition. Mn(II) binds only at the high affinity, so-called A site, whereas Fe(II) binds also at the low affinity, so-called B site. The Mn-Fe and Fe-Fe centers behave distinctly upon iron oxidation by O2. A site-bound Mn(II) or Fe(II) plays a catalytic role, while B site-bound Fe(II) behaves like a substrate and can be replaced by another Fe(II) after oxidation. When H2O2 is the Fe(II) oxidant, single electrons are transferred to aromatic residues near the ferroxidase center and give rise to intra-protein radicals thereby limiting OH release in solution. The presence of the Mn-Fe center results in significant differences in the development of such intra-protein radicals. CONCLUSIONS Mn(II) bound at the Dps ferroxidase center A site undergoes redox cycling provided the B site contains Fe. GENERAL SIGNIFICANCE The results provide a likely molecular mechanism for the protective role of Mn(II) under oxidative stress conditions as it participates in redox cycling in the hetero-binuclear ferroxidase center.
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Affiliation(s)
- Matteo Ardini
- Department of Biochemical Sciences A. Rossi Fanelli, Sapienza University of Rome, Italy
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18
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Mu W, Guan L, Yan Y, Liu Q, Zhang Y. A novel in vivo inducible expression system in Edwardsiella tarda for potential application in bacterial polyvalence vaccine. FISH & SHELLFISH IMMUNOLOGY 2011; 31:1097-1105. [PMID: 21964456 DOI: 10.1016/j.fsi.2011.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 08/20/2011] [Accepted: 09/19/2011] [Indexed: 05/31/2023]
Abstract
Recombinant bacterial vector vaccine is an attractive vaccination strategy to induce the immune response to a carried protective antigen, and the main concern of bacterial vector vaccine is to establish a stable antigen expression system in vector bacteria. Edwardsiella tarda is an important facultative intracellular pathogen of both animals and humans, and its attenuated derivates are excellent bacterial vectors for use in recombinant vaccine design. In this study, we design an in vivo inducible expression system in E. tarda and establish potential recombinant E. tarda vector vaccines. With wild type strain E. tarda EIB202 as a vector, 53 different bacteria-originated promoters were examined for iron-responsive transcription in vitro, and the promoters P(dps) and P(yncE) showed high transcription activity. The transcription profiles in vivo of two promoters were further assayed, and P(dps) revealed an enhanced in vivo inducible transcription in macrophage, larvae and adult zebra fish. The gapA34 gene, encoding the protective antigen GAPDH from the fish pathogen Aeromonas hydrophila LSA34, was introduced into the P(dps)-based protein expression system, and transformed into attenuated E. tarda strains. The resultant recombinant vector vaccine WED/pUTDgap was evaluated in turbot (Scophtalmus maximus). Over 60% of the vaccinated fish survived under the challenge with A. hydrophila LSA34 and E. tarda EIB202, suggesting that the P(dps)-based antigen delivery system had great potential in bacterial vector vaccine application.
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Affiliation(s)
- Wei Mu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
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19
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Mapping the regulon of Vibrio cholerae ferric uptake regulator expands its known network of gene regulation. Proc Natl Acad Sci U S A 2011; 108:12467-72. [PMID: 21750152 DOI: 10.1073/pnas.1107894108] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
ChIP coupled with next-generation sequencing (ChIP-seq) has revolutionized whole-genome mapping of DNA-binding protein sites. Although ChIP-seq rapidly gained support in eukaryotic systems, it remains underused in the mapping of bacterial transcriptional regulator-binding sites. Using the virulence-required iron-responsive ferric uptake regulator (Fur), we report a simple, broadly applicable ChIP-seq method in the pathogen Vibrio cholerae. Combining our ChIP-seq results with available microarray data, we clarify direct and indirect Fur regulation of known iron-responsive genes. We validate a subset of Fur-binding sites in vivo and show a common motif present in all Fur ChIP-seq peaks that has enhanced binding affinity for purified V. cholerae Fur. Further analysis shows that V. cholerae Fur directly regulates several additional genes associated with Fur-binding sites, expanding the role of this transcription factor into the regulation of ribosome formation, additional transport functions, and unique sRNAs.
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20
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Listeria monocytogenes PrsA2 is required for virulence factor secretion and bacterial viability within the host cell cytosol. Infect Immun 2010; 78:4944-57. [PMID: 20823208 DOI: 10.1128/iai.00532-10] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the course of establishing its replication niche within the cytosol of infected host cells, the facultative intracellular bacterial pathogen Listeria monocytogenes must efficiently regulate the secretion and activity of multiple virulence factors. L. monocytogenes encodes two predicted posttranslocation secretion chaperones, PrsA1 and PrsA2, and evidence suggests that PrsA2 has been specifically adapted for bacterial pathogenesis. PrsA-like chaperones have been identified in a number of Gram-positive bacteria, where they are reported to function at the bacterial membrane-cell wall interface to assist in the folding of proteins translocated across the membrane; in some cases, these proteins have been found to be essential for bacterial viability. In this study, the contributions of PrsA2 and PrsA1 to L. monocytogenes growth and protein secretion were investigated in vitro and in vivo. Neither PrsA2 nor PrsA1 was found to be essential for L. monocytogenes growth in broth culture; however, optimal bacterial viability was found to be dependent upon PrsA2 for L. monocytogenes located within the cytosol of host cells. Proteomic analyses of prsA2 mutant strains in the presence of a mutationally activated allele of the virulence regulator PrfA revealed a critical requirement for PrsA2 activity under conditions of PrfA activation, an event which normally takes place within the host cell cytosol. Despite a high degree of amino acid similarity, no detectable degree of functional overlap was observed between PrsA2 and PrsA1. Our results indicate a critical requirement for PrsA2 under conditions relevant to host cell infection.
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21
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Mohamed W, Sethi S, Darji A, Mraheil MA, Hain T, Chakraborty T. Antibody targeting the ferritin-like protein controls Listeria infection. Infect Immun 2010; 78:3306-14. [PMID: 20439472 PMCID: PMC2897390 DOI: 10.1128/iai.00210-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 04/02/2010] [Accepted: 04/25/2010] [Indexed: 11/20/2022] Open
Abstract
The acquisition of iron during the infection process is essential for the growth of pathogenic microorganisms (S. C. Andrews, Adv. Microb. Physiol. 40:281-351, 1998; H. M. Baker, B. F. Anderson, and E. N. Baker, Proc. Natl. Acad. Sci. U. S. A. 100:3579-3583, 2003). Since the solubility of iron is low and it is toxic at low concentrations, following uptake, iron is stored in subcellular microenvironments in the iron storage protein ferritin (C. Cheers and M. Ho, J. Reticuloendothel. Soc. 34:299-309, 1983). Here, we show that ferritin-like proteins (Frl) are highly conserved in the genus Listeria and demonstrate that these proteins are present in both the cytoplasm and cell wall fractions of these bacteria. Even though Frl is expressed under different growth conditions, transcriptional mapping revealed that its regulation is complex. When bacteria are grown in brain heart infusion medium, extracellular expression involves both sigma A (SigA)- and sigma B (SigB)-dependent promoters; however, during intracellular growth, initiation of transcription is additionally SigB dependent. The expression of Frl is greatly enhanced in bacteria grown in the presence of blood, and a mutant strain lacking the frl gene was defective for growth in this medium. Using the monoclonal antibody (MAb) specific for Frl, we demonstrate that administration of anti-Frl MAb prior to infection confers antilisterial resistance in vivo, evidenced in reduced bacterial load and increased survival rates, thereby demonstrating the in vivo significance of upregulated cell surface-associated Frl expression. In vitro studies revealed that the antilisterial resistance is due to increased listerial phagocytosis.
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Affiliation(s)
- Walid Mohamed
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Shneh Sethi
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Ayub Darji
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Mobarak A. Mraheil
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Torsten Hain
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Trinad Chakraborty
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
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22
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Miles S, Carpenter BM, Gancz H, Merrell DS. Helicobacter pylori apo-Fur regulation appears unconserved across species. J Microbiol 2010; 48:378-86. [PMID: 20571957 DOI: 10.1007/s12275-010-0022-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 02/08/2010] [Indexed: 11/30/2022]
Abstract
The Ferric Uptake Regulator (Fur) is a transcriptional regulator that is conserved across a broad number of bacterial species and has been shown to regulate expression of iron uptake and storage genes. Additionally, Fur has been shown to be an important colonization factor of the gastric pathogen Helicobacter pylori. In H. pylori, Fur-dependent regulation appears to be unique in that Fur is able to act as a transcriptional repressor when bound to iron as well as in its iron free (apo) form. To date, apo-regulation has not been identified in any other bacterium. To determine whether Fur from other species has the capacity for apo-regulation, we investigated the ability of Fur from Escherichia coli, Campylobacter jejuni, Desulfovibrio vulgaris Hildenborough, Pseudomonas aeruginosa, and Vibrio cholerae to complement both iron-bound and apo-Fur regulation within the context of a H. pylori fur mutant. We found that while some Fur species (E. coli, C. jejuni, and V. cholerae) complemented iron-bound regulation, apo-regulation was unable to be complemented by any of the examined species. These data suggest that despite the conservation among bacterial Fur proteins, H. pylori Fur contains unique structure/function features that make it novel in comparison to Fur from other species.
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Affiliation(s)
- Shana Miles
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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23
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Transcriptomic response of Listeria monocytogenes to iron limitation and Fur mutation. Appl Environ Microbiol 2009; 76:406-16. [PMID: 19933349 DOI: 10.1128/aem.01389-09] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Iron is required by almost all bacteria, but concentrations above physiological levels are toxic. In bacteria, intracellular iron is regulated mostly by the ferric uptake regulator, Fur, or a similar functional protein. Iron limitation results in the regulation of a number of genes, especially those involved in iron uptake. A subset of these genes is the Fur regulon under the control of Fur. In the present study, we have identified Fur- and iron-regulated genes in Listeria monocytogenes by DNA microarray analysis using a fur mutant and its isogenic parent. To identify genes regulated exclusively in response to iron limitation, the whole-genome transcriptional responses to the iron limitation of a fur mutant and its isogenic parent were compared. Fur-regulated genes were identified by comparing the transcriptional profile of the parent with the transcriptional profile of the isogenic fur mutant. Our studies have identified genes regulated exclusively in response to iron and those that are negatively regulated by Fur. We have identified at least 14 genes that were negatively regulated directly by Fur. Under iron-limited conditions, these genes were upregulated, while the expression of fur was found to be downregulated. To further investigate the regulation of fur in response to iron, an ectopic fur promoter-lacZ transcriptional fusion strain was constructed, and its isogenic fur and perR mutant derivatives were generated in L. monocytogenes 10403S. Analysis of the iron limitation of the perR mutant indicated that the regulation of genes under the negative control of Fur was significantly inhibited. Our results indicate that Fur and PerR proteins negatively regulate fur and that under iron-limited conditions, PerR is required for the negative regulation of genes controlled by Fur.
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24
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Tsou CC, Chiang-Ni C, Lin YS, Chuang WJ, Lin MT, Liu CC, Wu JJ. Oxidative stress and metal ions regulate a ferritin-like gene, dpr, in Streptococcus pyogenes. Int J Med Microbiol 2009; 300:259-64. [PMID: 19879189 DOI: 10.1016/j.ijmm.2009.09.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 09/27/2009] [Accepted: 09/29/2009] [Indexed: 11/28/2022] Open
Abstract
Bacteria encounter oxidative stress by exposure to reactive oxygen species (ROS) present in the aerobic environment and during immune responses. In Streptococcus pyogenes, Dpr has been identified as a stress protein conferring resistance to hydrogen peroxide and multiple other stresses. The expression of Dpr is under perR (peroxide stress response regulator) control. However, the exact molecular mechanism of PerR regulation of Dpr is not clear. In this study, a perR deletion mutant was constructed by double cross-over mutagenesis. The profile of Dpr expression, performed by Western blot assay, revealed growth-phase dependency under normal culture conditions. Dpr expression decreased under iron-restricted conditions, whereas iron, zinc, nickel, and hydrogen peroxide induced its expression. The perR mutant does not induce Dpr as well when exposed to environmental signals. PerR binds the promoter region of dpr. Increased iron and hydrogen peroxide concentrations decreased PerR binding to the promoter region of dpr, suggesting that regulation of Dpr by environmental signals is mediated by PerR directly.
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Affiliation(s)
- Chih-Cheng Tsou
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan, Taiwan
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25
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Yu MJ, Ren J, Zeng YL, Zhou SN, Lu YJ. The Legionella pneumophila Dps homolog is regulated by iron and involved in multiple stress tolerance. J Basic Microbiol 2009; 49 Suppl 1:S79-86. [PMID: 19455515 DOI: 10.1002/jobm.200800357] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Iron homeostasis is essential to almost all organisms. In this study, we identified the putative homolog of the iron-storage protein-encoding gene, dpsL, in the intracellular pathogen Legionella pneumophila and demonstrated its expression under iron-limited conditions and its responses to multiple stresses. Quantitative real-time PCR analysis indicated that the expression of dpsL was enhanced under iron limitation regardless of the growth phase. Compared with the wild-type cells, the cells devoid of dpsL were heat and H(2)O(2)-sensitive. In contrast to the dps mutants of other bacteria, the growth of the dpsL mutant in an iron-deprived medium was delayed but finally reached the same cell density as wild-type cells during the stationary phase of growth. The finding that the dpsL mutant is salt resistant suggested the involvement of DpsL in virulence.
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Affiliation(s)
- Ming-Jia Yu
- Department of Biochemistry, Sun Yat-sen University Guangzhou, China
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26
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This is not your mother's repressor: the complex role of fur in pathogenesis. Infect Immun 2009; 77:2590-601. [PMID: 19364842 DOI: 10.1128/iai.00116-09] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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