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Marmion M, Macori G, Barroug S, Soro AB, Bourke P, Tiwari BK, Whyte P, Scannell AGM. Added insult to injury? The response of meat-associated pathogens to proposed antimicrobial interventions. Appl Microbiol Biotechnol 2024; 108:87. [PMID: 38189954 PMCID: PMC10774175 DOI: 10.1007/s00253-023-12849-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 10/20/2023] [Accepted: 10/25/2023] [Indexed: 01/09/2024]
Abstract
Modern requirements for 'green label' meat products have led to the design of novel antimicrobial innovations which prioritise quality, safety and longevity. Plasma-functionalised water (PFW), ultraviolet light and natural antimicrobial compositions have been investigated and optimised for control of foodborne pathogens like Campylobacter jejuni and Salmonella enterica serovar Typhimurium. However, given the adaptive mechanisms present in bacteria under external stresses, it is imperative to understand the effect that sublethal treatment may have on the bacterial transcriptome. In this study, Salmonella Typhimurium and C. jejuni were treated with sublethal doses of ultraviolet light, a citrus juice/essential oil marinade, and 'spark' or 'glow' cold plasma generation system-produced PFW. Immediately after treatment, cells were lysed and RNA was extracted and purified. mRNA was converted to cDNA by reverse transcription-PCR and sequenced by an Illumina MiSeq® system. Sequences were filtered and analysed using the Tuxedo workflow. Sublethal treatment of Campylobacter jejuni and Salmonella Typhimurium led to increased immediate cellular and metabolic activity, as well as diversification in protein and metabolic functioning. There was further expression of pathogenesis and virulence-associated traits associated with spark PFW and marinade treatment of Salmonella Typhimurium. However, similar concerns were not raised with glow PFW or UV-treated samples. This study provides science-based evidence of the efficacy of multi-hurdle antimicrobial system using green-label marinades and PFW or UV to inactivate pathogens without upregulating virulence traits in surviving cells. This study will inform policymakers and food industry stakeholders and reinforces the need to incorporate in-line novel technologies to ensure consumer safety. KEY POINTS: • Salmonella and C. jejuni showed increased cell activity in immediate response to stress. • Virulence genes showed increased expression when treated with natural antimicrobials and sPFW. • Reduced immediate transcriptomic response to gPFW and UV treatment indicates lower risk.
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Affiliation(s)
- Maitiú Marmion
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland.
- UCD Centre for Food Safety, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland.
| | - Guerrino Macori
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
- UCD Centre for Food Safety, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
| | - Soukaina Barroug
- UCD School of Biosystems and Engineering, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
| | - Arturo B Soro
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
- Department of Food Chemistry and Technology, Teagasc Food Research Centre, Ashtown, Dublin 15, D15 KN3K, Ireland
| | - Paula Bourke
- UCD School of Biosystems and Engineering, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
| | - Brijesh K Tiwari
- Department of Food Chemistry and Technology, Teagasc Food Research Centre, Ashtown, Dublin 15, D15 KN3K, Ireland
| | - Paul Whyte
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
| | - Amalia G M Scannell
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
- UCD Centre for Food Safety, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
- UCD Institute of Food and Health, University College Dublin, Belfield, Dublin 4, D04V4W8, Ireland
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Gavriil A, Giannenas I, Skandamis PN. A current insight into Salmonella's inducible acid resistance. Crit Rev Food Sci Nutr 2024:1-21. [PMID: 39014992 DOI: 10.1080/10408398.2024.2373387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Salmonella is a diverse and ubiquitous group of bacteria and a major zoonotic pathogen implicated in several foodborne disease outbreaks worldwide. With more than 2500 distinct serotypes, this pathogen has evolved to survive in a wide spectrum of environments and across multiple hosts. The primary and most common source of transmission is through contaminated food or water. Although the main sources have been primarily linked to animal-related food products, outbreaks due to the consumption of contaminated plant-related food products have increased in the last few years. The perceived ability of Salmonella to trigger defensive mechanisms following pre-exposure to sublethal acid conditions, namely acid adaptation, has renewed a decade-long attention. The impact of acid adaptation on the subsequent resistance against lethal factors of the same or multiple stresses has been underscored by multiple studies. Α plethora of studies have been published, aiming to outline the factors that- alone or in combination- can impact this phenomenon and to unravel the complex networking mechanisms underlying its induction. This review aims to provide a current and updated insight into the factors and mechanisms that rule this phenomenon.
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Affiliation(s)
- Alkmini Gavriil
- Department of Natural Resources Management and Agricultural Engineering, Agricultural University of Athens, Athens, Greece
- Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Ilias Giannenas
- School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Panagiotis N Skandamis
- Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
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Zhang C, Liu J, Liu X, Xu Y, Gan Q, Cheng Q, Liu W, Gao X, Wu S. Glutamine enhances pneumococcal growth under methionine semi-starvation by elevating intracellular pH. Front Microbiol 2024; 15:1430038. [PMID: 39044959 PMCID: PMC11263215 DOI: 10.3389/fmicb.2024.1430038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 06/28/2024] [Indexed: 07/25/2024] Open
Abstract
Introduction Bacteria frequently encounter nutrient limitation in nature. The ability of living in this nutrient shortage environment is vital for bacteria to preserve their population and important for some pathogenic bacteria to cause infectious diseases. Usually, we study how bacteria survive after nutrient depletion, a total starvation condition when bacteria almost cease growth and try to survive. However, nutrient limitation may not always lead to total starvation. Methods Bacterial adaptation to nutrient shortage was studied by determining bacterial growth curves, intracellular pH, intracellular amino acid contents, gene transcription, protein expression, enzyme activity, and translation and replication activities. Results No exogenous supply of methionine results in growth attenuation of Streptococcus pneumoniae, a human pathogen. In this paper, we refer to this inhibited growth state between ceased growth under total starvation and full-speed growth with full nutrients as semi-starvation. Similar to total starvation, methionine semi-starvation also leads to intracellular acidification. Surprisingly, it is intracellular acidification but not insufficient methionine synthesis that causes growth attenuation under methionine semi-starvation. With excessive glutamine supply in the medium, intracellular methionine level was not changed, while bacterial intracellular pH was elevated to ~ 7.6 (the optimal intracellular pH for pneumococcal growth) by glutamine deamination, and bacterial growth under semi-starvation was restored fully. Our data suggest that intracellular acidification decreases translation level and glutamine supply increases intracellular pH to restore translation level, thus restoring bacterial growth. Discussion This growth with intracellular pH adjustment by glutamine is a novel strategy we found for bacterial adaptation to nutrient shortage, which may provide new drug targets to inhibit growth of pathogenic bacteria under semi-starvation.
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Affiliation(s)
- Chengwang Zhang
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Juncheng Liu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Xiaohui Liu
- National Protein Science Facility, Tsinghua University, Beijing, China
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Yueyu Xu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Qingxiu Gan
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Qinqian Cheng
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Weiping Liu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Xiangmin Gao
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
| | - Songquan Wu
- Department of Basic Medical Science, School of Medicine, Lishui University, Lishui, Zhejiang, China
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Kenney LJ. Peeling the onion: additional layers of regulation in the acid stress response. J Bacteriol 2024; 206:e0006924. [PMID: 38488356 PMCID: PMC11025319 DOI: 10.1128/jb.00069-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024] Open
Abstract
Bacteria are capable of withstanding large changes in osmolality and cytoplasmic pH, unlike eukaryotes that tightly regulate their pH and cellular composition. Previous studies on the bacterial acid stress response described a rapid, brief acidification, followed by immediate recovery. More recent experiments with better pH probes have imaged single living cells, and we now appreciate that following acid stress, bacteria maintain an acidic cytoplasm for as long as the stress remains. This acidification enables pathogens to sense a host environment and turn on their virulence programs, for example, enabling survival and replication within acidic vacuoles. Single-cell analysis identified an intracellular pH threshold of ~6.5. Acid stress reduces the internal pH below this threshold, triggering the assembly of a type III secretion system in Salmonella and the secretion of virulence factors in the host. These pathways are significant because preventing intracellular acidification of Salmonella renders it avirulent, suggesting that acid stress pathways represent a potential therapeutic target. Although we refer to the acid stress response as singular, it is actually a complex response that involves numerous two-component signaling systems, several amino acid decarboxylation systems, as well as cellular buffering systems and electron transport chain components, among others. In a recent paper in the Journal of Bacteriology, M. G. Gorelik, H. Yakhnin, A. Pannuri, A. C. Walker, C. Pourciau, D. Czyz, T. Romeo, and P. Babitzke (J Bacteriol 206:e00354-23, 2024, https://doi.org/10.1128/jb.00354-23) describe a new connection linking the carbon storage regulator CsrA to the acid stress response, highlighting new additional layers of complexity.
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Affiliation(s)
- Linda J. Kenney
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch Galveston, Galveston, Texas, USA
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Ghoshal M, Bechtel TD, Gibbons JG, McLandsborough L. Transcriptomic analysis using RNA sequencing and phenotypic analysis of Salmonella enterica after acid exposure for different time durations using adaptive laboratory evolution. Front Microbiol 2024; 15:1348063. [PMID: 38476938 PMCID: PMC10929716 DOI: 10.3389/fmicb.2024.1348063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/30/2024] [Indexed: 03/14/2024] Open
Abstract
Introduction This study is the final part of a two-part series that delves into the molecular mechanisms driving adaptive laboratory evolution (ALE) of Salmonella enterica in acid stress. The phenotypic and transcriptomic alterations in the acid-evolved lineages (EL) of Salmonella enterica serovar Enteritidis after 70 days of acid stress exposure were analyzed. Materials and methods The stability of phenotypic changes observed after 70 days in acetic acid was explored after stress removal using a newly developed evolutionary lineage EL5. Additionally, the impact of short-term acid stress on the previously adapted lineage EL4 was also examined. Results The results indicate that the elevated antibiotic minimum inhibitory concentration (MIC) observed after exposure to acetic acid for 70 days was lost when acid stress was removed. This phenomenon was observed against human antibiotics such as meropenem, ciprofloxacin, gentamicin, and streptomycin. The MIC of meropenem in EL4 on day 70 was 0.094 mM, which dropped to 0.032 mM when removed from acetic acid stress after day 70. However, after stress reintroduction, the MIC swiftly elevated, and within 4 days, it returned to 0.094 mM. After 20 more days of adaptation in acetic acid, the meropenem MIC increased to 0.125 mM. The other human antibiotics that were tested exhibited a similar trend. The MIC of acetic acid in EL4 on day 70 was observed to be 35 mM, which remained constant even after the removal of acetic acid stress. Readaptation of EL4 in acetic acid for 20 more days caused the acetic acid MIC to increase to 37 mM. Bacterial whole genome sequencing of EL5 revealed base substitutions in several genes involved in pathogenesis, such as the phoQ and wzc genes. Transcriptomic analysis of EL5 revealed upregulation of virulence, drug resistance, toxin-antitoxin, and iron metabolism genes. Unstable Salmonella small colony variants (SSCV) of S. Enteritidis were also observed in EL5 as compared to the wild-type unevolved S. Enteritidis. Discussion This study presents a comprehensive understanding of the evolution of the phenotypic, genomic, and transcriptomic changes in S. Enteritidis due to prolonged acid exposure through ALE.
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Affiliation(s)
- Mrinalini Ghoshal
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
- Department of Food Science, University of Massachusetts, Amherst, MA, United States
| | - Tyler D. Bechtel
- Department of Food Science, University of Massachusetts, Amherst, MA, United States
| | - John G. Gibbons
- Department of Food Science, University of Massachusetts, Amherst, MA, United States
| | - Lynne McLandsborough
- Department of Food Science, University of Massachusetts, Amherst, MA, United States
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Singh MK, Kenney LJ. Visualizing the invisible: novel approaches to visualizing bacterial proteins and host-pathogen interactions. Front Bioeng Biotechnol 2024; 12:1334503. [PMID: 38415188 PMCID: PMC10898356 DOI: 10.3389/fbioe.2024.1334503] [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: 11/07/2023] [Accepted: 01/19/2024] [Indexed: 02/29/2024] Open
Abstract
Host-pathogen interactions play a critical role in infectious diseases, and understanding the underlying mechanisms is vital for developing effective therapeutic strategies. The visualization and characterization of bacterial proteins within host cells is key to unraveling the dynamics of these interactions. Various protein labeling strategies have emerged as powerful tools for studying host-pathogen interactions, enabling the tracking, localization, and functional analysis of bacterial proteins in real-time. However, the labeling and localization of Salmonella secreted type III secretion system (T3SS) effectors in host cells poses technical challenges. Conventional methods disrupt effector stoichiometry and often result in non-specific staining. Bulky fluorescent protein fusions interfere with effector secretion, while other tagging systems such as 4Cys-FLaSH/Split-GFP suffer from low labeling specificity and a poor signal-to-noise ratio. Recent advances in state-of-the-art techniques have augmented the existing toolkit for monitoring the translocation and dynamics of bacterial effectors. This comprehensive review delves into the bacterial protein labeling strategies and their application in imaging host-pathogen interactions. Lastly, we explore the obstacles faced and potential pathways forward in the realm of protein labeling strategies for visualizing interactions between hosts and pathogens.
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Affiliation(s)
- Moirangthem Kiran Singh
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
| | - Linda J. Kenney
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, United States
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Chen X, Alakavuklar MA, Fiebig A, Crosson S. Cross-regulation in a three-component cell envelope stress signaling system of Brucella. mBio 2023; 14:e0238723. [PMID: 38032291 PMCID: PMC10746171 DOI: 10.1128/mbio.02387-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
IMPORTANCE As intracellular pathogens, Brucella must contend with a variety of host-derived stressors when infecting a host cell. The inner membrane, cell wall, and outer membrane, i.e. the cell envelope, of Brucella provide a critical barrier to host assault. A conserved regulatory mechanism known as two-component signaling (TCS) commonly controls transcription of genes that determine the structure and biochemical composition of the cell envelope during stress. We report the identification of previously uncharacterized TCS genes that determine Brucella ovis fitness in the presence of cell envelope disruptors and within infected mammalian host cells. Our study reveals a new molecular mechanism of TCS-dependent gene regulation, and thereby advances fundamental understanding of transcriptional regulatory processes in bacteria.
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Affiliation(s)
- Xingru Chen
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Melene A. Alakavuklar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Aretha Fiebig
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Sean Crosson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
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Wagner GE, Stanjek TFP, Albrecht D, Lipp M, Dunachie SJ, Föderl-Höbenreich E, Riedel K, Kohler A, Steinmetz I, Kohler C. Deciphering the human antibody response against Burkholderia pseudomallei during melioidosis using a comprehensive immunoproteome approach. Front Immunol 2023; 14:1294113. [PMID: 38146371 PMCID: PMC10749318 DOI: 10.3389/fimmu.2023.1294113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/22/2023] [Indexed: 12/27/2023] Open
Abstract
Introduction The environmental bacterium Burkholderia pseudomallei causes the often fatal and massively underreported infectious disease melioidosis. Antigens inducing protective immunity in experimental models have recently been identified and serodiagnostic tools have been improved. However, further elucidation of the antigenic repertoire of B. pseudomallei during human infection for diagnostic and vaccine purposes is required. The adaptation of B. pseudomallei to very different habitats is reflected by a huge genome and a selective transcriptional response to a variety of conditions. We, therefore, hypothesized that exposure of B. pseudomallei to culture conditions mimicking habitats encountered in the human host might unravel novel antigens that are recognized by melioidosis patients. Methods and results In this study, B. pseudomallei was exposed to various stress and growth conditions, including anaerobiosis, acid stress, oxidative stress, iron starvation and osmotic stress. Immunogenic proteins were identified by probing two-dimensional Western blots of B. pseudomallei intracellular and extracellular protein extracts with sera from melioidosis patients and controls and subsequent MALDI-TOF MS. Among B. pseudomallei specific immunogenic signals, 90 % (55/61) of extracellular immunogenic proteins were identified by acid, osmotic or oxidative stress. A total of 84 % (44/52) of intracellular antigens originated from the stationary growth phase, acidic, oxidative and anaerobic conditions. The majority of the extracellular and intracellular protein antigens were identified in only one of the various stress conditions. Sixty-three immunoreactive proteins and an additional 38 candidates from a literature screening were heterologously expressed and subjected to dot blot analysis using melioidosis sera and controls. Our experiments confirmed melioidosis-specific signals in 58 of our immunoproteome candidates. These include 15 antigens with average signal ratios (melioidosis:controls) greater than 10 and another 26 with average ratios greater than 5, including new promising serodiagnostic candidates with a very high signal-to-noise ratio. Conclusion Our study shows that a comprehensive B. pseudomallei immunoproteomics approach, using conditions which are likely to be encountered during infection, can identify novel antibody targets previously unrecognized in human melioidosis.
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Affiliation(s)
- Gabriel E. Wagner
- Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
| | | | - Dirk Albrecht
- Institute of Microbiology, Department of Microbial Physiology and Molecular Biology, University of Greifswald, Greifswald, Germany
| | - Michaela Lipp
- Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Susanna J. Dunachie
- Nuffield Department of Medicine (NDM) Centre for Global Health Research, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- National Institute for Health and Care Research (NIHR) Oxford Biomedical Centre, Oxford University Hospitals National Health Service (NHS) Foundation Trust, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Esther Föderl-Höbenreich
- Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
- Diagnostic & Research Institute of Pathology, Medical University Graz, Graz, Austria
| | - Katharina Riedel
- Institute of Microbiology, Department of Microbial Physiology and Molecular Biology, University of Greifswald, Greifswald, Germany
| | - Anne Kohler
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine, Greifswald, Germany
| | - Ivo Steinmetz
- Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine, Greifswald, Germany
| | - Christian Kohler
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine, Greifswald, Germany
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Li W, Ren Q, Ni T, Zhao Y, Sang Z, Luo R, Li Z, Li S. Strategies adopted by Salmonella to survive in host: a review. Arch Microbiol 2023; 205:362. [PMID: 37904066 DOI: 10.1007/s00203-023-03702-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 09/30/2023] [Accepted: 10/05/2023] [Indexed: 11/01/2023]
Abstract
Salmonella, a Gram-negative bacterium that infects humans and animals, causes diseases ranging from gastroenteritis to severe systemic infections. Here, we discuss various strategies used by Salmonella against host cell defenses. Epithelial cell invasion largely depends on a Salmonella pathogenicity island (SPI)-1-encoded type 3 secretion system, a molecular syringe for injecting effector proteins directly into host cells. The internalization of Salmonella into macrophages is primarily driven by phagocytosis. After entering the host cell cytoplasm, Salmonella releases many effectors to achieve intracellular survival and replication using several secretion systems, primarily an SPI-2-encoded type 3 secretion system. Salmonella-containing vacuoles protect Salmonella from contacting bactericidal substances in epithelial cells and macrophages. Salmonella modulates the immunity, metabolism, cell cycle, and viability of host cells to expand its survival in the host, and the intracellular environment of Salmonella-infected cells promotes its virulence. This review provides insights into how Salmonella subverts host cell defenses for survival.
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Affiliation(s)
- Wanwu Li
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
| | - Qili Ren
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
| | - Ting Ni
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
| | - Yifei Zhao
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
| | - Zichun Sang
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
| | - Renli Luo
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
| | - Zhongjie Li
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China.
| | - Sanqiang Li
- College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China.
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10
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Chen X, Alakavuklar MA, Fiebig A, Crosson S. Cross regulation in a three-component cell envelope stress signaling system of Brucella. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.15.536747. [PMID: 37873345 PMCID: PMC10592609 DOI: 10.1101/2023.04.15.536747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
A multi-layered structure known as the cell envelope separates the controlled interior of bacterial cells from a fluctuating physical and chemical environment. The transcription of genes that determine cell envelope structure and function is commonly regulated by two-component signaling systems (TCS), comprising a sensor histidine kinase and a cognate response regulator. To identify TCS genes that contribute to cell envelope function in the intracellular mammalian pathogen, Brucella ovis, we subjected a collection of non-essential TCS deletion mutants to compounds that disrupt cell membranes and the peptidoglycan cell wall. Our screen led to the discovery of three TCS proteins that coordinately function to confer resistance to cell envelope stressors and to support B. ovis replication in the intracellular niche. This tripartite regulatory system includes the known cell envelope regulator, CenR, and a previously uncharacterized TCS, EssR-EssS, which is widely conserved in Alphaproteobacteria. The CenR and EssR response regulators bind a shared set of sites on the B. ovis chromosomes to control transcription of an overlapping set of genes with cell envelope functions. CenR directly interacts with EssR and functions to stimulate phosphoryl transfer from the EssS kinase to EssR, while CenR and EssR control the cellular levels of each other via a post-transcriptional mechanism. Our data provide evidence for a new mode of TCS cross-regulation in which a non-cognate response regulator affects both the activity and protein levels of a cognate TCS protein pair.
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Affiliation(s)
- Xingru Chen
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
| | - Melene A Alakavuklar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
| | - Aretha Fiebig
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
| | - Sean Crosson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan USA
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11
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Pokorzynski ND, Groisman EA. How Bacterial Pathogens Coordinate Appetite with Virulence. Microbiol Mol Biol Rev 2023; 87:e0019822. [PMID: 37358444 PMCID: PMC10521370 DOI: 10.1128/mmbr.00198-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023] Open
Abstract
Cells adjust growth and metabolism to nutrient availability. Having access to a variety of carbon sources during infection of their animal hosts, facultative intracellular pathogens must efficiently prioritize carbon utilization. Here, we discuss how carbon source controls bacterial virulence, with an emphasis on Salmonella enterica serovar Typhimurium, which causes gastroenteritis in immunocompetent humans and a typhoid-like disease in mice, and propose that virulence factors can regulate carbon source prioritization by modifying cellular physiology. On the one hand, bacterial regulators of carbon metabolism control virulence programs, indicating that pathogenic traits appear in response to carbon source availability. On the other hand, signals controlling virulence regulators may impact carbon source utilization, suggesting that stimuli that bacterial pathogens experience within the host can directly impinge on carbon source prioritization. In addition, pathogen-triggered intestinal inflammation can disrupt the gut microbiota and thus the availability of carbon sources. By coordinating virulence factors with carbon utilization determinants, pathogens adopt metabolic pathways that may not be the most energy efficient because such pathways promote resistance to antimicrobial agents and also because host-imposed deprivation of specific nutrients may hinder the operation of certain pathways. We propose that metabolic prioritization by bacteria underlies the pathogenic outcome of an infection.
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Affiliation(s)
- Nick D. Pokorzynski
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
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12
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Shetty D, Kenney LJ. A pH-sensitive switch activates virulence in Salmonella. eLife 2023; 12:e85690. [PMID: 37706506 PMCID: PMC10519707 DOI: 10.7554/elife.85690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 09/13/2023] [Indexed: 09/15/2023] Open
Abstract
The transcriptional regulator SsrB acts as a switch between virulent and biofilm lifestyles of non-typhoidal Salmonella enterica serovar Typhimurium. During infection, phosphorylated SsrB activates genes on Salmonella Pathogenicity Island-2 (SPI-2) essential for survival and replication within the macrophage. Low pH inside the vacuole is a key inducer of expression and SsrB activation. Previous studies demonstrated an increase in SsrB protein levels and DNA-binding affinity at low pH; the molecular basis was unknown (Liew et al., 2019). This study elucidates its underlying mechanism and in vivo significance. Employing single-molecule and transcriptional assays, we report that the SsrB DNA-binding domain alone (SsrBc) is insufficient to induce acid pH-sensitivity. Instead, His12, a conserved residue in the receiver domain confers pH sensitivity to SsrB allosterically. Acid-dependent DNA binding was highly cooperative, suggesting a new configuration of SsrB oligomers at SPI-2-dependent promoters. His12 also plays a role in SsrB phosphorylation; substituting His12 reduced phosphorylation at neutral pH and abolished pH-dependent differences. Failure to flip the switch in SsrB renders Salmonella avirulent and represents a potential means of controlling virulence.
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Affiliation(s)
- Dasvit Shetty
- Mechanobiology Institute, National University of SingaporeSingaporeSingapore
| | - Linda J Kenney
- Mechanobiology Institute, National University of SingaporeSingaporeSingapore
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at GalvestonGalvestonUnited States
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch at GalvestonGalvestonUnited States
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13
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Li A, Fan J, Jia Y, Tang X, Chen J, Shen C. Phenotype and metabolism alterations in PCB-degrading Rhodococcus biphenylivorans TG9 T under acid stress. J Environ Sci (China) 2023; 127:441-452. [PMID: 36522076 DOI: 10.1016/j.jes.2022.05.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/11/2022] [Accepted: 05/12/2022] [Indexed: 06/17/2023]
Abstract
Environmental acidification impairs microorganism diversity and their functions on substance transformation. Rhodococcus is a ubiquitously distributed genus for contaminant detoxification in the environment, and it can also adapt a certain range of pH. This work interpreted the acid responses from both phenotype and metabolism in strain Rhodococcus biphenylivorans TG9T (TG9) induced at pH 3. The phenotype alterations were described with the number of culturable and viable cells, intracellular ATP concentrations, cell shape and entocyte, degradation efficiency of polychlorinated biphenyl (PCB) 31 and biphenyl. The number of culturable cells maintained rather stable within the first 10 days, even though the other phenotypes had noticeable alterations, indicating that TG9 possesses certain capacities to survive under acid stress. The metabolism responses were interpreted based on transcription analyses with four treatments including log phase (LP), acid-induced (PER), early recovery after removing acid (RE) and later recovery (REL). With the overview on the expression regulations among the 4 treatments, the RE sample presented more upregulated and less downregulated genes, suggesting that its metabolism was somehow more active after recovering from acid stress. In addition, the response mechanism was interpreted on 10 individual metabolism pathways mainly covering protein modification, antioxidation, antipermeability, H+ consumption, neutralization and extrusion. Furthermore, the transcription variations were verified with RT-qPCR on 8 genes with 24-hr, 48-hr and 72-hr acid treatment. Taken together, TG9 possesses comprehensive metabolism strategies defending against acid stress. Consequently, a model was built to provide an integrate insight to understand the acid resistance/tolerance metabolisms in microorganisms.
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Affiliation(s)
- Aili Li
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jiahui Fan
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yangyang Jia
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xianjin Tang
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jingwen Chen
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Chaofeng Shen
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
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14
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Gebremichael Y, Crandall J, Mukhopadhyay R, Xu F. Salmonella Subpopulations Identified from Human Specimens Express Heterogenous Phenotypes That Are Relevant to Clinical Diagnosis. Microbiol Spectr 2023; 11:e0167922. [PMID: 36507668 PMCID: PMC9927314 DOI: 10.1128/spectrum.01679-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 11/08/2022] [Indexed: 12/15/2022] Open
Abstract
Clonal bacterial cells can give rise to functionally heterogeneous subpopulations. This diversification is considered an adaptation strategy that has been demonstrated for several bacterial species, including Salmonella enterica serovar Typhimurium. In previous studies on mouse models infected orally with pure Salmonella cultures, derived bacterial cells collected from animal tissues were found to express heterogenous phenotypes. Here, we show mixed Salmonella populations, apparently derived from the same progenitor, present in human specimens collected at a single disease time point, and in a long-term-infected patient, these Salmonella were no longer expressing surface-exposed antigen epitopes by isolates collected at earlier days of the disease. The subpopulations express different phenotypes related to cell surface antigen expression, motility, biofilm formation, biochemical metabolism, and antibiotic resistance, which can all contribute to pathogenicity. Some of the phenotypes correlate with single nucleotide polymorphisms or other sequence changes in bacterial genomes. These genetic variations can alter synthesis of cell membrane-associated molecules such as lipopolysaccharides and lipoproteins, leading to changes in bacterial surface structure and function. This study demonstrates the limitation of Salmonella diagnostic methods that are based on a single-cell population which may not represent the heterogenous bacterial community in infected humans. IMPORTANCE In animal model systems, heterogenous Salmonella phenotypes were found previously to regulate bacterial infections. We describe in this communication that different Salmonella phenotypes also exist in infected humans at a single disease time point and that their phenotypic and molecular traits are associated with different aspects of pathogenicity. Notably, variation in genes encoding antibiotic resistance and two-component systems were observed from the subpopulations of a patient suffering from persistent salmonellosis. Therefore, clinical and public health interventions of the disease that are based on diagnosis of a single-cell population may miss other subpopulations that can cause residual human infections.
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Affiliation(s)
- Yismashoa Gebremichael
- Microbial Diseases Laboratory, California Department of Public Health, Richmond, California, USA
| | - John Crandall
- Microbial Diseases Laboratory, California Department of Public Health, Richmond, California, USA
| | - Rituparna Mukhopadhyay
- Microbial Diseases Laboratory, California Department of Public Health, Richmond, California, USA
| | - Fengfeng Xu
- Microbial Diseases Laboratory, California Department of Public Health, Richmond, California, USA
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15
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Schwarz J, Schumacher K, Brameyer S, Jung K. Bacterial battle against acidity. FEMS Microbiol Rev 2022; 46:6652135. [PMID: 35906711 DOI: 10.1093/femsre/fuac037] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 01/09/2023] Open
Abstract
The Earth is home to environments characterized by low pH, including the gastrointestinal tract of vertebrates and large areas of acidic soil. Most bacteria are neutralophiles, but can survive fluctuations in pH. Herein, we review how Escherichia, Salmonella, Helicobacter, Brucella, and other acid-resistant Gram-negative bacteria adapt to acidic environments. We discuss the constitutive and inducible defense mechanisms that promote survival, including proton-consuming or ammonia-producing processes, cellular remodeling affecting membranes and chaperones, and chemotaxis. We provide insights into how Gram-negative bacteria sense environmental acidity using membrane-integrated and cytosolic pH sensors. Finally, we address in more detail the powerful proton-consuming decarboxylase systems by examining the phylogeny of their regulatory components and their collective functionality in a population.
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Affiliation(s)
- Julia Schwarz
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kilian Schumacher
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Sophie Brameyer
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kirsten Jung
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
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16
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López‐Escarpa D, Castanheira S, García‐del Portillo F. OmpR and Prc contribute to switch the Salmonella morphogenetic program in response to phagosome cues. Mol Microbiol 2022; 118:477-493. [PMID: 36115022 PMCID: PMC9827838 DOI: 10.1111/mmi.14982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 01/12/2023]
Abstract
Salmonella enterica serovar Typhimurium infects eukaryotic cells residing within membrane-bound phagosomes. In this compartment, the pathogen replaces the morphogenetic penicillin-binding proteins 2 and 3 (PBP2/PBP3) with PBP2SAL /PBP3SAL , two proteins absent in Escherichia coli. The basis for this switch is unknown. Here, we show that PBP3 protein levels drop drastically when S. Typhimurium senses acidity, high osmolarity and nutrient scarcity, cues that activate virulence functions required for intra-phagosomal survival and proliferation. The protease Prc and the transcriptional regulator OmpR contribute to lower PBP3 levels whereas OmpR stimulates PBP2SAL /PBP3SAL production. Surprisingly, despite being essential for division in E. coli, PBP3 levels also drop in non-pathogenic and pathogenic E. coli exposed to phagosome cues. Such exposure alters E. coli morphology resulting in very long bent and twisted filaments indicative of failure in the cell division and elongation machineries. None of these aberrant shapes are detected in S. Typhimurium. Expression of PBP3SAL restores cell division in E. coli exposed to phagosome cues although the cells retain elongation defects in the longitudinal axis. By switching the morphogenetic program, OmpR and Prc allow S. Typhimurium to properly divide and elongate inside acidic phagosomes maintaining its cellular dimensions and the rod shape.
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Affiliation(s)
- David López‐Escarpa
- Laboratory of Intracellular Bacterial PathogensNational Centre for Biotechnology (CNB‐CSIC)MadridSpain
| | - Sónia Castanheira
- Laboratory of Intracellular Bacterial PathogensNational Centre for Biotechnology (CNB‐CSIC)MadridSpain
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17
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Xiao G, Zheng X, Li J, Yang Y, Yang J, Xiao N, Liu J, Sun Z. Contribution of the EnvZ/OmpR two-component system to growth, virulence and stress tolerance of colistin-resistant Aeromonas hydrophila. Front Microbiol 2022; 13:1032969. [PMID: 36312957 PMCID: PMC9597241 DOI: 10.3389/fmicb.2022.1032969] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/26/2022] [Indexed: 01/07/2024] Open
Abstract
Aeromonas hydrophila is an important zoonotic pathogen responsible for septicemia, diarrhea and gastroenteritis, and has attracted considerable attention. The EnvZ/OmpR two-component system (TCS) mediates environmental stress responses in gram-negative bacteria. We investigated the role of the TCS in A. hydrophila by comparing the characteristics of the parental (23-C-23), EnvZ/OmpR knockout (23-C-23:ΔEnvZ/OmpR), and complemented strains (23-C-23:CΔEnvZ/OmpR). Under non-stress conditions, the 23-C-23:ΔEnvZ/OmpR strain showed a significant decrease in growth rate compared to that of 23-C-23. Transcriptome and metabonomic analysis indicated that many metabolic pathways were remarkably affected in the ΔEnvZ/OmpR strain, including the TCA cycle and arginine biosynthesis. In addition, the virulence of the ΔEnvZ/OmpR strain was attenuated in a Kunming mouse model. The ΔEnvZ/OmpR strain exhibited notably reduced tolerance to environmental stresses, including high temperature, different pH conditions, oxidative stress, and high osmotic stress. The downregulated expression of genes related to cell metabolism, motility, and virulence in the ΔEnvZ/OmpR mutant strain was further validated by real-time quantitative PCR. Consequently, our data suggest that the EnvZ/OmpR TCS is required for growth, motility, virulence, and stress response in A. hydrophila, which has significant implications in the development of novel antibacterial and vaccine therapies targeting EnvZ/OmpR against A. hydrophila.
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Affiliation(s)
- Gang Xiao
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha, China
| | - Xiaofeng Zheng
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha, China
| | - Jiyun Li
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha, China
| | - Yang Yang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
| | - Jie Yang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha, China
| | - Ning Xiao
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha, China
| | - Junqi Liu
- Veterinary Drug Laboratory, Hunan Institute of Animal and Veterinary Science, Changsha, China
| | - Zhiliang Sun
- College of Veterinary Medicine, Hunan Agricultural University, Changsha, China
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha, China
- National Research Center of Engineering and Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha, China
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18
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Nitrate Utilization Promotes Systemic Infection of Salmonella Typhimurium in Mice. Int J Mol Sci 2022; 23:ijms23137220. [PMID: 35806223 PMCID: PMC9266322 DOI: 10.3390/ijms23137220] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 06/24/2022] [Accepted: 06/27/2022] [Indexed: 02/07/2023] Open
Abstract
Salmonella Typhimurium is an invasive enteric pathogen that causes gastroenteritis in humans and life-threatening systemic infections in mice. During infection of the intestine, S. Typhimurium can exploit nitrate as an electron acceptor to enhance its growth. However, the roles of nitrate on S. Typhimurium systemic infection are unknown. In this study, nitrate levels were found to be significantly increased in the liver and spleen of mice systemically infected by S. Typhimurium. Mutations in genes encoding nitrate transmembrane transporter (narK) or nitrate-producing flavohemoprotein (hmpA) decreased the replication of S. Typhimurium in macrophages and reduced systemic infection in vivo, suggesting that nitrate utilization promotes S. Typhimurium systemic virulence. Moreover, nitrate utilization contributes to the acidification of the S. Typhimurium cytoplasm, which can sustain the virulence of S. Typhimurium by increasing the transcription of virulence genes encoding on Salmonella pathogenicity island 2 (SPI-2). Furthermore, the growth advantage of S. Typhimurium conferred by nitrate utilization occurred only under low-oxygen conditions, and the nitrate utilization was activated by both the global regulator Fnr and the nitrate-sensing two-component system NarX-NarL. Collectively, this study revealed a novel mechanism adopted by Salmonella to interact with its host and increase its virulence.
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Sobota M, Rodilla Ramirez PN, Cambré A, Rocker A, Mortier J, Gervais T, Haas T, Cornillet D, Chauvin D, Hug I, Julou T, Aertsen A, Diard M. The expression of virulence genes increases membrane permeability and sensitivity to envelope stress in Salmonella Typhimurium. PLoS Biol 2022; 20:e3001608. [PMID: 35389980 PMCID: PMC9017878 DOI: 10.1371/journal.pbio.3001608] [Citation(s) in RCA: 1] [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: 08/20/2021] [Revised: 04/19/2022] [Accepted: 03/17/2022] [Indexed: 11/19/2022] Open
Abstract
Virulence gene expression can represent a substantial fitness cost to pathogenic bacteria. In the model entero-pathogen Salmonella Typhimurium (S.Tm), such cost favors emergence of attenuated variants during infections that harbor mutations in transcriptional activators of virulence genes (e.g., hilD and hilC). Therefore, understanding the cost of virulence and how it relates to virulence regulation could allow the identification and modulation of ecological factors to drive the evolution of S.Tm toward attenuation. In this study, investigations of membrane status and stress resistance demonstrate that the wild-type (WT) expression level of virulence factors embedded in the envelope increases membrane permeability and sensitizes S.Tm to membrane stress. This is independent from a previously described growth defect associated with virulence gene expression in S.Tm. Pretreating the bacteria with sublethal stress inhibited virulence expression and increased stress resistance. This trade-off between virulence and stress resistance could explain the repression of virulence expression in response to harsh environments in S.Tm. Moreover, we show that virulence-associated stress sensitivity is a burden during infection in mice, contributing to the inherent instability of S.Tm virulence. As most bacterial pathogens critically rely on deploying virulence factors in their membrane, our findings could have a broad impact toward the development of antivirulence strategies.
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Affiliation(s)
| | | | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | | | - Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Théo Gervais
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | | | | | - Dany Chauvin
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Isabelle Hug
- Biozentrum, University of Basel, Basel, Switzerland
| | - Thomas Julou
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
- * E-mail: (AA); (MD)
| | - Médéric Diard
- Biozentrum, University of Basel, Basel, Switzerland
- * E-mail: (AA); (MD)
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20
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Ma Z, Li NA, Ning C, Liu Y, Guo Y, Ji C, Zhu X, Meng Q, Xia X, Zhang X, Cai X, Cai K, Jun Q. A Novel LysR Family Factor STM0859 is Associated with The Responses of Salmonella Typhimurium to Environmental Stress and Biofilm Formation. Pol J Microbiol 2022; 70:479-487. [PMID: 35003279 PMCID: PMC8702606 DOI: 10.33073/pjm-2021-045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/04/2021] [Indexed: 12/01/2022] Open
Abstract
Salmonella enterica subsp. enterica serovar Typhimurium (ST) is an intracellularly parasitic bacterium. This zoonotic pathogen causes food poisoning and thus imposes a severe threat to food safety. Here, to understand the regulatory roles of the novel transcription factor STM0859 on the response of ST to environmental stress and biofilm formation, the STM0859 gene-deficient strain and the complementation strain ΔSTM0859/STM0859 were generated, respectively. Then, its capacity of responding to environmental stresses and biofilm (BF) formation ability under different stresses, including acid, alkali, high salt, cholate, and oxidative stresses was tested. We further analyzed the interaction between the STM0859 protein and the promoter of the acid stress response-related gene rcsB by performing an electrophoresis mobility shift assay (EMSA). The results showed that acid resistance and BF formation capacities of ST-ΔSTM0859 strain were significantly weaker, as compared with those of Salmonella Typhimurium SL1344 (ST-SL1344) wild strain (p < 0.01). Quantitative qRT-PCR analysis showed that the expression levels of acid stress and BF formation-related genes, rcsB and rpoS, of ST-ΔSTM0859 strain were significantly reduced at the transcription levels, while the transcription levels of these genes were fully restored in complementation strain ST-ΔSTM0859/STM0859. The results of EMSA showed that STM0859 was capable of binding the promoter DNA fragments of the rcsB gene, suggesting that STM0859 can promote the transcription of the rcsB gene through interaction with its promoter, thereby exerting an indirectly regulatory role on the adaptive responses to acid stress and BF formation of ST. This study provided new insights into the regulatory mechanisms of the LysR family factors on the tolerances of ST under adverse environmental stresses.
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Affiliation(s)
- Zhongmei Ma
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - N A Li
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Chengcheng Ning
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Yucheng Liu
- Institute of Animal Science and Veterinary Research, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi, China
| | - Yun Guo
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Chunhui Ji
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Xiaozhen Zhu
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Qingling Meng
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Xianzhu Xia
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Xingxing Zhang
- Institute of Animal Science and Veterinary Research, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi, China
| | - Xuepeng Cai
- State Key Lab of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Kuojun Cai
- Center for Animal Disease Prevention and Control, Urumqi, China
| | - Qiao Jun
- College of Animal Science and Technology, Shihezi University, Shihezi, China
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21
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Peptidoglycan editing in non-proliferating intracellular Salmonella as source of interference with immune signaling. PLoS Pathog 2022; 18:e1010241. [PMID: 35077524 PMCID: PMC8815878 DOI: 10.1371/journal.ppat.1010241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/04/2022] [Accepted: 01/01/2022] [Indexed: 02/07/2023] Open
Abstract
Salmonella enterica causes intracellular infections that can be limited to the intestine or spread to deeper tissues. In most cases, intracellular bacteria show moderate growth. How these bacteria face host defenses that recognize peptidoglycan, is poorly understood. Here, we report a high-resolution structural analysis of the minute amounts of peptidoglycan purified from S. enterica serovar Typhimurium (S. Typhimurium) infecting fibroblasts, a cell type in which this pathogen undergoes moderate growth and persists for days intracellularly. The peptidoglycan of these non-proliferating bacteria contains atypical crosslinked muropeptides with stem peptides trimmed at the L-alanine-D-glutamic acid-(γ) or D-glutamic acid-(γ)-meso-diaminopimelic acid motifs, both sensed by intracellular immune receptors. This peptidoglycan has a reduced glycan chain average length and ~30% increase in the L,D-crosslink, a type of bridge shared by all the atypical crosslinked muropeptides identified. The L,D-transpeptidases LdtD (YcbB) and LdtE (YnhG) are responsible for the formation of these L,D-bridges in the peptidoglycan of intracellular bacteria. We also identified in a fraction of muropeptides an unprecedented modification in the peptidoglycan of intracellular S. Typhimurium consisting of the amino alcohol alaninol replacing the terminal (fourth) D-alanine. Alaninol was still detectable in the peptidoglycan of a double mutant lacking LdtD and LdtE, thereby ruling out the contribution of these enzymes to this chemical modification. Remarkably, all multiple mutants tested lacking candidate enzymes that either trim stem peptides or form the L,D-bridges retain the capacity to modify the terminal D-alanine to alaninol and all attenuate NF-κB nuclear translocation. These data inferred a potential role of alaninol-containing muropeptides in attenuating pro-inflammatory signaling, which was confirmed with a synthetic tetrapeptide bearing such amino alcohol. We suggest that the modification of D-alanine to alaninol in the peptidoglycan of non-proliferating intracellular S. Typhimurium is an editing process exploited by this pathogen to evade immune recognition inside host cells. The peptidoglycan, built as a giant polymer of glycan chains crosslinked with short peptides, is essential for cell shape and survival in most bacteria. Its unique chemistry is recognized by innate immune receptors, thereby enabling neutralization of invading microbes. A striking feature of the peptidoglycan is its constant remodeling by a plethora of endogenous enzymes. In addition, some bacterial pathogens introduce structural modifications that interfere with immune recognition. These modifications have been characterized in pathogens mostly in laboratory nutrient media. Whether facultative intracellular pathogens modify peptidoglycan structure inside host cells, was unknown. The work presented here shows that non-proliferating Salmonella enterica serovar Typhimurium remodels the peptidoglycan structure in response to intracellular cues and that some of these modifications involve unprecedented changes as the presence of an amino alcohol that hampers activation of the master immune regulator NF-κB. Peptidoglycan editing might therefore empower persistence of bacterial pathogens in the intracellular niche.
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22
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Vaughn B, Abu Kwaik Y. Idiosyncratic Biogenesis of Intracellular Pathogens-Containing Vacuoles. Front Cell Infect Microbiol 2021; 11:722433. [PMID: 34858868 PMCID: PMC8632064 DOI: 10.3389/fcimb.2021.722433] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/25/2021] [Indexed: 12/12/2022] Open
Abstract
While most bacterial species taken up by macrophages are degraded through processing of the bacteria-containing vacuole through the endosomal-lysosomal degradation pathway, intravacuolar pathogens have evolved to evade degradation through the endosomal-lysosomal pathway. All intra-vacuolar pathogens possess specialized secretion systems (T3SS-T7SS) that inject effector proteins into the host cell cytosol to modulate myriad of host cell processes and remodel their vacuoles into proliferative niches. Although intravacuolar pathogens utilize similar secretion systems to interfere with their vacuole biogenesis, each pathogen has evolved a unique toolbox of protein effectors injected into the host cell to interact with, and modulate, distinct host cell targets. Thus, intravacuolar pathogens have evolved clear idiosyncrasies in their interference with their vacuole biogenesis to generate a unique intravacuolar niche suitable for their own proliferation. While there has been a quantum leap in our knowledge of modulation of phagosome biogenesis by intravacuolar pathogens, the detailed biochemical and cellular processes affected remain to be deciphered. Here we discuss how the intravacuolar bacterial pathogens Salmonella, Chlamydia, Mycobacteria, Legionella, Brucella, Coxiella, and Anaplasma utilize their unique set of effectors injected into the host cell to interfere with endocytic, exocytic, and ER-to-Golgi vesicle traffic. However, Coxiella is the main exception for a bacterial pathogen that proliferates within the hydrolytic lysosomal compartment, but its T4SS is essential for adaptation and proliferation within the lysosomal-like vacuole.
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Affiliation(s)
- Bethany Vaughn
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, United States
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, United States.,Center for Predictive Medicine, College of Medicine, University of Louisville, Louisville, KY, United States
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23
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Singh MK, Kenney LJ. Super-resolution imaging of bacterial pathogens and visualization of their secreted effectors. FEMS Microbiol Rev 2021; 45:5911101. [PMID: 32970796 DOI: 10.1093/femsre/fuaa050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 09/17/2020] [Indexed: 12/13/2022] Open
Abstract
Recent advances in super-resolution imaging techniques, together with new fluorescent probes have enhanced our understanding of bacterial pathogenesis and their interplay within the host. In this review, we provide an overview of what these techniques have taught us about the bacterial lifestyle, the nucleoid organization, its complex protein secretion systems, as well as the secreted virulence factors.
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Affiliation(s)
- Moirangthem Kiran Singh
- Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Linda J Kenney
- Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
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Kenney LJ. How Can a Histidine Kinase Respond to Mechanical Stress? Front Microbiol 2021; 12:655942. [PMID: 34335491 PMCID: PMC8320348 DOI: 10.3389/fmicb.2021.655942] [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: 01/19/2021] [Accepted: 06/08/2021] [Indexed: 11/30/2022] Open
Abstract
Bacteria respond to physical forces perceived as mechanical stress as part of their comprehensive environmental sensing strategy. Histidine kinases can then funnel diverse environmental stimuli into changes in gene expression through a series of phosphorelay reactions. Because histidine kinases are most often embedded in the inner membrane, they can be sensitive to changes in membrane tension that occurs, for example, in response to osmotic stress, or when deformation of the cell body occurs upon encountering a surface before forming biofilms, or inside the host in response to shear stress in the kidney, intestine, lungs, or blood stream. A summary of our recent work that links the histidine kinase EnvZ to mechanical changes in the inner membrane is provided and placed in a context of other bacterial systems that respond to mechanical stress.
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Affiliation(s)
- Linda J Kenney
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
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Hussain S, Ouyang P, Zhu Y, Khalique A, He C, Liang X, Shu G, Yin L. Type 3 secretion system 1 of Salmonella typhimurium and its inhibitors: a novel strategy to combat salmonellosis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:34154-34166. [PMID: 33966165 DOI: 10.1007/s11356-021-13986-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Unsuccessful vaccination against Salmonella due to a large number of serovars, and antibiotic resistance, necessitates the development of novel therapeutics to treat salmonellosis. The development of anti-virulence agents against multi-drug-resistant bacteria is a novel strategy because of its non-bacterial feature. Hence, a thorough study of the type three secretion system (T3SS) of Salmonella would help us better understand its role in bacterial pathogenesis and development of anti-virulence agents. However, T3SS can be inhibited by different chemicals at different stages of infection and sequenced delivery of effectors can be blocked to restrict the progression of disease. This review highlights the role of T3SS-1 in the internalization, survival, and replication of Salmonella within the intestinal epithelium and T3SS inhibitors. We concluded that the better we understand the structures and functions of T3SS, the more we have chances to develop anti-virulence agents. Furthermore, greater insights into the T3SS inhibitors of Salmonella would help in the mitigation of the antibiotic resistance problem and would lead us to the era of new therapeutics against salmonellosis.
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Affiliation(s)
- Sajjad Hussain
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Ping Ouyang
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Yingkun Zhu
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Abdul Khalique
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Changliang He
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Xiaoxia Liang
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Gang Shu
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China
| | - Lizi Yin
- College of Veterinary Medicine, Sichuan Agriculture University, Huimin Road 211, Wenjiang, Chengdu, China.
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Wójcicki M, Świder O, Daniluk KJ, Średnicka P, Akimowicz M, Roszko MŁ, Sokołowska B, Juszczuk-Kubiak E. Transcriptional Regulation of the Multiple Resistance Mechanisms in Salmonella-A Review. Pathogens 2021; 10:pathogens10070801. [PMID: 34202800 PMCID: PMC8308502 DOI: 10.3390/pathogens10070801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 02/07/2023] Open
Abstract
The widespread use of antibiotics, especially those with a broad spectrum of activity, has resulted in the development of multidrug resistance in many strains of bacteria, including Salmonella. Salmonella is among the most prevalent causes of intoxication due to the consumption of contaminated food and water. Salmonellosis caused by this pathogen is pharmacologically treated using antibiotics such as fluoroquinolones, ceftriaxone, and azithromycin. This foodborne pathogen developed several molecular mechanisms of resistance both on the level of global and local transcription modulators. The increasing rate of antibiotic resistance in Salmonella poses a significant global concern, and an improved understanding of the multidrug resistance mechanisms in Salmonella is essential for choosing the suitable antibiotic for the treatment of infections. In this review, we summarized the current knowledge of molecular mechanisms that control gene expression related to antibiotic resistance of Salmonella strains. We characterized regulators acting as transcription activators and repressors, as well as two-component signal transduction systems. We also discuss the background of the molecular mechanisms of the resistance to metals, regulators of multidrug resistance to antibiotics, global regulators of the LysR family, as well as regulators of histone-like proteins.
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Affiliation(s)
- Michał Wójcicki
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
| | - Olga Świder
- Department of Food Safety and Chemical Analysis, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (O.Ś.); (M.Ł.R.)
| | - Kamila J. Daniluk
- Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (K.J.D.); (B.S.)
| | - Paulina Średnicka
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
| | - Monika Akimowicz
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
| | - Marek Ł. Roszko
- Department of Food Safety and Chemical Analysis, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (O.Ś.); (M.Ł.R.)
| | - Barbara Sokołowska
- Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (K.J.D.); (B.S.)
| | - Edyta Juszczuk-Kubiak
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
- Correspondence: ; Tel.: +48-22-6063605
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Singh MK, Zangoui P, Yamanaka Y, Kenney LJ. Genetic code expansion enables visualization of Salmonella type three secretion system components and secreted effectors. eLife 2021; 10:67789. [PMID: 34061032 PMCID: PMC8192122 DOI: 10.7554/elife.67789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/22/2021] [Indexed: 12/14/2022] Open
Abstract
Type three secretion systems enable bacterial pathogens to inject effectors into the cytosol of eukaryotic hosts to reprogram cellular functions. It is technically challenging to label effectors and the secretion machinery without disrupting their structure/function. Herein, we present a new approach for labeling and visualization of previously intractable targets. Using genetic code expansion, we site-specifically labeled SsaP, the substrate specificity switch, and SifA, a here-to-fore unlabeled secreted effector. SsaP was secreted at later infection times; SsaP labeling demonstrated the stochasticity of injectisome and effector expression. SifA was labeled after secretion into host cells via fluorescent unnatural amino acids or non-fluorescent labels and a subsequent click reaction. We demonstrate the superiority of imaging after genetic code expansion compared to small molecule tags. It provides an alternative for labeling proteins that do not tolerate N- or C-terminal tags or fluorophores and thus is widely applicable to other secreted effectors and small proteins.
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Affiliation(s)
- Moirangthem Kiran Singh
- Mechanobiology Institute, T-Lab, 5A Engineering Drive 1, National University of Singapore, Singapore, Singapore.,Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, United States
| | - Parisa Zangoui
- Mechanobiology Institute, T-Lab, 5A Engineering Drive 1, National University of Singapore, Singapore, Singapore.,Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, United States
| | - Yuki Yamanaka
- Mechanobiology Institute, T-Lab, 5A Engineering Drive 1, National University of Singapore, Singapore, Singapore
| | - Linda J Kenney
- Mechanobiology Institute, T-Lab, 5A Engineering Drive 1, National University of Singapore, Singapore, Singapore.,Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, United States
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28
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Gomez-Arrebola C, Solano C, Lasa I. Regulation of gene expression by non-phosphorylated response regulators. Int Microbiol 2021; 24:521-529. [PMID: 33987704 DOI: 10.1007/s10123-021-00180-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 12/26/2022]
Abstract
Two-component systems (TCSs) are a prominent sensory system in bacteria. A prototypical TCS comprises a membrane-bound sensor histidine kinase (HK) responsible for sensing the signal and a cytoplasmic response regulator (RR) that controls target gene expression. Signal binding activates a phosphotransfer cascade from the HK to the RR. As a result, the phosphorylated RR undergoes a conformational change that leads to activation of the response. Growing experimental evidence indicates that unphosphorylated RRs may also have regulatory functions, and thus, the classical view that the RR is only active when it is phosphorylated needs to be revisited. In this review, we highlight the most recent findings showing that RRs in the non-phosphorylated state control critical bacterial processes that range from secretion of factors to the host, antibiotic resistance, iron transport, stress response, and cell-wall metabolism to biofilm development.
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Affiliation(s)
- Carmen Gomez-Arrebola
- Laboratory of Microbial Pathogenesis, Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IdiSNA, Irunlarrea 3, 31008, Pamplona, Navarra, Spain
| | - Cristina Solano
- Laboratory of Microbial Pathogenesis, Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IdiSNA, Irunlarrea 3, 31008, Pamplona, Navarra, Spain
| | - Iñigo Lasa
- Laboratory of Microbial Pathogenesis, Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IdiSNA, Irunlarrea 3, 31008, Pamplona, Navarra, Spain.
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29
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Mendoza-Mejía BD, Medina-Aparicio L, Serrano-Fujarte I, Vázquez A, Calva E, Hernández-Lucas I. Salmonella enterica serovar Typhi genomic regions involved in low pH resistance and in invasion and replication in human macrophages. ANN MICROBIOL 2021. [DOI: 10.1186/s13213-021-01629-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Purpose
Salmonella enterica serovar Typhi, the etiological agent of typhoid fever, causes a systemic life-threatening disease. To carry out a successful infection process, this bacterium needs to survive alkaline and acid pH conditions presented in the mouth, stomach, small intestine, and gallbladder. Therefore, in this work, a genetic screening to identify S. Typhi genes involved in acid and circumneutral pH resistance was performed.
Methods
A collection of S. Typhi mutants deleted of fragments ranging from 6 to 80 kb were obtained by the Datsenko and Wanner method. Bacterial growth rate assays of each mutant were performed to identify S. Typhi genes involved in circumneutral and acid pH resistance. S. Typhi mutants deficient to growth at specific pH were evaluated in their capacity to invade and replicate in phagocytic cells.
Results
In this work, it is reported that S. Typhi ∆F4 (pH 4.5), S. Typhi ∆F44 (pH 4.5, 5.5, and 6.5), and S. Typhi ∆F73 (pH 4.5, 5.5, 6.5, and 7.5) were deficient to grow in the pH indicated. These three mutant strains were also affected in their ability to invade and replicate in human macrophages.
Conclusions
S. Typhi contains defined genomic regions that influence the survival at specific pH values, as well as the invasion and replication inside human cells. Thus, this genetic information probably allows the bacteria to survive in different human compartments for an efficient infection cycle.
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30
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Gu D, Xue H, Yuan X, Yu J, Xu X, Huang Y, Li M, Zhai X, Pan Z, Zhang Y, Jiao X. Genome-Wide Identification of Genes Involved in Acid Stress Resistance of Salmonella Derby. Genes (Basel) 2021; 12:genes12040476. [PMID: 33806186 PMCID: PMC8065570 DOI: 10.3390/genes12040476] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/23/2021] [Accepted: 03/23/2021] [Indexed: 02/05/2023] Open
Abstract
Resistance to and survival under acidic conditions are critical for Salmonella to infect the host. As one of the most prevalent serotypes identified in pigs and humans, how S. Derby overcomes acid stress remains unclear. Here, we de novo sequenced the genome of a representative S. Derby strain 14T from our S. Derby strain stock and identified its acid resistance-associated genes using Tn-seq analysis. A total of 35 genes, including those belonging to two-component systems (TCS) (cpxAR), the CRISPR-Cas system (casCE), and other systems, were identified as essential for 14T to survive under acid stress. The results demonstrated that the growth curve and survival ability of ΔcpxA and ΔcpxR were decreased under acid stress, and the adhesion and invasion abilities to the mouse colon cancer epithelial cells (MC38) of ΔcpxR were also decreased compared with the wild type strain, suggesting that the TCS CpxAR plays an essential role in the acid resistance and virulence of S. Derby. Also, CasC and CasE were found to be responsible for acid resistance in S. Derby. Our results indicate that acid stress induces multiple genes’ expression to mediate the acid resistance of S. Derby and enhance its pathogenesis during an infection.
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Affiliation(s)
- Dan Gu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Han Xue
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Xiaohui Yuan
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Jinyan Yu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Xiaomeng Xu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Yu Huang
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Mingzhu Li
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Xianyue Zhai
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Zhiming Pan
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
| | - Yunzeng Zhang
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
- Correspondence:
| | - Xinan Jiao
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; (D.G.); (H.X.); (X.Y.); (J.Y.); (X.X.); (Y.H.); (M.L.); (X.Z.); (Z.P.); (X.J.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou 225009, China
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Abundant Monovalent Ions as Environmental Signposts for Pathogens during Host Colonization. Infect Immun 2021; 89:IAI.00641-20. [PMID: 33526568 DOI: 10.1128/iai.00641-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Host colonization by a pathogen requires proper sensing and response to local environmental cues, to ensure adaptation and continued survival within the host. The ionic milieu represents a critical potential source of environmental cues, and indeed, there has been extensive study of the interplay between host and pathogen in the context of metals such as iron, zinc, and manganese, vital ions that are actively sequestered by the host. The inherent non-uniformity of the ionic milieu also extends, however, to "abundant" ions such as chloride and potassium, whose concentrations vary greatly between tissue and cellular locations, and with the immune response. Despite this, the concept of abundant ions as environmental cues and key players in host-pathogen interactions is only just emerging. Focusing on chloride and potassium, this review brings together studies across multiple bacterial and parasitic species that have begun to define both how these abundant ions are exploited as cues during host infection, and how they can be actively manipulated by pathogens during host colonization. The close links between ion homeostasis and sensing/response to different ionic signals, and the importance of studying pathogen response to cues in combination, are also discussed, while considering the fundamental insight still to be uncovered from further studies in this nascent area of inquiry.
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Ji X, Lu P, Xue J, Zhao N, Zhang Y, Dong L, Zhang X, Li P, Hu Y, Wang J, Zhang B, Liu J, Lv H, Wang S. The lipoprotein NlpD in Cronobacter sakazakii responds to acid stress and regulates macrophage resistance and virulence by maintaining membrane integrity. Virulence 2021; 12:415-429. [PMID: 33459158 PMCID: PMC7834084 DOI: 10.1080/21505594.2020.1870336] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cronobacter sakazakii, an emerging opportunistic pathogen, is implicated in severe foodborne outbreak infections in premature and full-term infants. Generally, acid tolerance is vital for the pathogenesis of foodborne pathogens; however, its role in C. sakazakii virulence remains largely unknown. To screen out acid-tolerance determinants from transposon mutants, anovel counterselection method using gentamicin and acid was developed. Using the counterselection method and growth assay, we screened several acid-sensitive mutants and found that nlpD encodes an acid-resistance factor in C. sakazakii. Compared to the wild-type strain, the nlpD mutant exhibited attenuated virulence in a rat model. Using macrophage THP-1 cells and a pH probe, we verified that nlpD enables bacteria to resist macrophages by resisting acidification. Finally, we confirmed that nlpD maintains C. sakazakii membrane integrity in acid using propidium iodide permeabilization assays via flow cytometry. Our results confirm that nlpD is a novel virulence factor that permits C. sakazakii to survive under acid stress conditions. Considering that NlpD is a conserved lipoprotein located in the bacterial outer membrane, NlpD could be used as a target for drug development.
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Affiliation(s)
- Xuemeng Ji
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Ping Lu
- Institute of Radiation Medicine, Chinese Academy of Medical Science and Peking Union Medical Collage , Tianjin, China
| | - Juan Xue
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine , Shiyan, China
| | - Ning Zhao
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Yan Zhang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Lu Dong
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Xuejiao Zhang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Ping Li
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology , Tianjin, China
| | - Yaozhong Hu
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Jin Wang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Bowei Zhang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Jingmin Liu
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Huan Lv
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
| | - Shuo Wang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University , Tianjin, China
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Xia K, Han C, Xu J, Liang X. Transcriptome response of Acetobacter pasteurianus Ab3 to high acetic acid stress during vinegar production. Appl Microbiol Biotechnol 2020; 104:10585-10599. [PMID: 33156446 DOI: 10.1007/s00253-020-10995-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 10/01/2020] [Accepted: 10/31/2020] [Indexed: 12/12/2022]
Abstract
Acetic acid accumulation is a universal limiting factor to the vinegar manufacture because of the toxic effect of acetic acid on the acid producing strain, such as Acetobacter pasteurianus. In this study, we aimed to investigate the genome-wide transcriptional response of A. pasteurianus Ab3 to high acid stress during vinegar production. By comparing the transcriptional landscape of cells harvested from a long-term cultivation with high acidity (70 ± 3 g/L) to that of low acidity (10 ± 2 g/L), we demonstrated that 1005 genes were differentially expressed. By functional enrichment analysis, we found that the expression of genes related to the two-component systems (TCS) and toxin-antitoxin systems (TAS) was significantly regulated under high acid stress. Cells increased the genome stability to withstand the intracellular toxicity caused by the acetic acid accumulation by repressing the expression of transposases and integrases. Moreover, high acid stress induced the expression of genes involved in the pathways of peptidoglycan, ceramide, and phosphatidylcholine biosynthesis as well as the Tol-Pal and TonB-ExbB systems. In addition, we observed that cells increased and diversified the ATP production to resist high acid stress. Transcriptional upregulation in the pathways of pyrroloquinoline quinone (PQQ) synthesis and thiamine metabolism suggested that cells may increase the production of prosthetic groups to ensure the enzyme activity upon high acid stress. Collectively, the results of this study increase our current understanding of the acetic acid resistance (AAR) mechanisms in A. pasteurianus and provide opportunities for strain improvement and scaled-up vinegar production.Key Points• TCS and TAS are responsive to the acid stress and constitute the regulating networks.• Adaptive expression changes of cell envelope elements help cell resist acid stress.• Cells promote genome stability and diversify ATP production to withstand acid stress.
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Affiliation(s)
- Kai Xia
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Chengcheng Han
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Jun Xu
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Xinle Liang
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China.
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China.
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Lund PA, De Biase D, Liran O, Scheler O, Mira NP, Cetecioglu Z, Fernández EN, Bover-Cid S, Hall R, Sauer M, O'Byrne C. Understanding How Microorganisms Respond to Acid pH Is Central to Their Control and Successful Exploitation. Front Microbiol 2020; 11:556140. [PMID: 33117305 PMCID: PMC7553086 DOI: 10.3389/fmicb.2020.556140] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/21/2020] [Indexed: 12/20/2022] Open
Abstract
Microbes from the three domains of life, Bacteria, Archaea, and Eukarya, share the need to sense and respond to changes in the external and internal concentrations of protons. When the proton concentration is high, acidic conditions prevail and cells must respond appropriately to ensure that macromolecules and metabolic processes are sufficiently protected to sustain life. While, we have learned much in recent decades about the mechanisms that microbes use to cope with acid, including the unique challenges presented by organic acids, there is still much to be gained from developing a deeper understanding of the effects and responses to acid in microbes. In this perspective article, we survey the key molecular mechanisms known to be important for microbial survival during acid stress and discuss how this knowledge might be relevant to microbe-based applications and processes that are consequential for humans. We discuss the research approaches that have been taken to investigate the problem and highlight promising new avenues. We discuss the influence of acid on pathogens during the course of infections and highlight the potential of using organic acids in treatments for some types of infection. We explore the influence of acid stress on photosynthetic microbes, and on biotechnological and industrial processes, including those needed to produce organic acids. We highlight the importance of understanding acid stress in controlling spoilage and pathogenic microbes in the food chain. Finally, we invite colleagues with an interest in microbial responses to low pH to participate in the EU-funded COST Action network called EuroMicropH and contribute to a comprehensive database of literature on this topic that we are making publicly available.
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Affiliation(s)
- Peter A Lund
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Daniela De Biase
- Department of Medico-Surgical Sciences and Biotechnologies, Laboratory affiliated to the Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Sapienza University of Rome, Latina, Italy
| | - Oded Liran
- Department of Plant Sciences, MIGAL - Galilee Research Institute, Kiryat-Shemona, Israel
| | - Ott Scheler
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Nuno Pereira Mira
- Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Zeynep Cetecioglu
- Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
| | | | - Sara Bover-Cid
- IRTA, Food Safety Programme, Finca Camps i Armet, Monells, Spain
| | - Rebecca Hall
- School of Biosciences, Kent Fungal Group, University of Kent, Canterbury, United Kingdom
| | - Michael Sauer
- Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Conor O'Byrne
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, NUI Galway, Galway, Ireland
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Antony L, Fenske G, Kaushik RS, Nagaraja TG, Thomas M, Scaria J. Population structure of Salmonella enterica serotype Mbandaka reveals similar virulence potential irrespective of source and phylogenomic stratification. F1000Res 2020; 9:1142. [PMID: 33214877 PMCID: PMC7653644 DOI: 10.12688/f1000research.25540.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/08/2020] [Indexed: 11/22/2022] Open
Abstract
Background: Salmonella enterica serotype Mbandaka ( Salmonella ser. Mbandaka) is a multi-host adapted Non-typhoidal Salmonella (NTS) that can cause foodborne illnesses in human. Outbreaks of Salmonella ser. Mbandaka contributed to the economic stress caused by NTS due to hospitalizations. Whole genome sequencing (WGS)-based phylogenomic analysis facilitates better understanding of the genomic features that may expedite the foodborne spread of Salmonella ser. Mbandaka. Methods: In the present study, we define the population structure, antimicrobial resistance (AMR), and virulence profile of Salmonella ser. Mbandaka using WGS data of more than 400 isolates collected from different parts of the world. We validated the genotypic prediction of AMR and virulence phenotypically using an available set of representative isolates. Results: Phylogenetic analysis of Salmonella ser. Mbandaka using Bayesian approaches revealed clustering of the population into two major groups; however, clustering of these groups and their subgroups showed no pattern based on the host or geographical origin. Instead, we found a uniform virulence gene repertoire in all isolates. Phenotypic analysis on a representative set of isolates showed a similar trend in cell invasion behavior and adaptation to a low pH environment. Both genotypic and phenotypic analysis revealed the carriage of multidrug resistance (MDR) genes in Salmonella ser. Mbandaka. Conclusions: Overall, our results show that the presence of multidrug resistance along with adaptation to broad range of hosts and uniformity in the virulence potential, isolates of Salmonella ser. Mbandaka from any source could have the potential to cause foodborne outbreaks as well as AMR dissemination.
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Affiliation(s)
- Linto Antony
- Department of Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
- South Dakota Center for Biologics Research and Commercialization, Brookings, SD, USA
| | - Gavin Fenske
- Department of Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
- South Dakota Center for Biologics Research and Commercialization, Brookings, SD, USA
| | - Radhey S Kaushik
- Department of Biology & Microbiology, South Dakota State University, Brookings, SD, 57007, USA
| | - Tiruvoor G Nagaraja
- Department of Diagnostic Medicine & Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, 66506, USA
| | - Milton Thomas
- Department of Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
| | - Joy Scaria
- Department of Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
- South Dakota Center for Biologics Research and Commercialization, Brookings, SD, USA
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The pneumococcal two-component system SirRH is linked to enhanced intracellular survival of Streptococcus pneumoniae in influenza-infected pulmonary cells. PLoS Pathog 2020; 16:e1008761. [PMID: 32790758 PMCID: PMC7447016 DOI: 10.1371/journal.ppat.1008761] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 08/25/2020] [Accepted: 06/29/2020] [Indexed: 12/18/2022] Open
Abstract
The virus-bacterial synergism implicated in secondary bacterial infections caused by Streptococcus pneumoniae following infection with epidemic or pandemic influenza A virus (IAV) is well documented. However, the molecular mechanisms behind such synergism remain largely ill-defined. In pneumocytes infected with influenza A virus, subsequent infection with S. pneumoniae leads to enhanced pneumococcal intracellular survival. The pneumococcal two-component system SirRH appears essential for such enhanced survival. Through comparative transcriptomic analysis between the ΔsirR and wt strains, a list of 179 differentially expressed genes was defined. Among those, the clpL protein chaperone gene and the psaB Mn+2 transporter gene, which are involved in the stress response, are important in enhancing S. pneumoniae survival in influenza-infected cells. The ΔsirR, ΔclpL and ΔpsaB deletion mutants display increased susceptibility to acidic and oxidative stress and no enhancement of intracellular survival in IAV-infected pneumocyte cells. These results suggest that the SirRH two-component system senses IAV-induced stress conditions and controls adaptive responses that allow survival of S. pneumoniae in IAV-infected pneumocytes.
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Kehl A, Noster J, Hensel M. Eat in or Take out? Metabolism of Intracellular Salmonella enterica. Trends Microbiol 2020; 28:644-654. [DOI: 10.1016/j.tim.2020.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 03/15/2020] [Accepted: 03/25/2020] [Indexed: 02/07/2023]
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Luiz de Freitas L, Aparecida Dos Santos CI, Carneiro DG, Dantas Vanetti MC. Nisin and acid resistance in Salmonella is enhanced by N-dodecanoyl-homoserine lactone. Microb Pathog 2020; 147:104320. [PMID: 32534181 DOI: 10.1016/j.micpath.2020.104320] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 01/22/2023]
Abstract
Salmonella is a foodborne pathogen that can develop resistance to different stresses, which is essential for successful infection of the host. Some genes directly related to acid resistance are also involved in cationic peptide resistance in Gram-negative bacteria and could be under the control of quorum sensing (QS) mediated by autoinducer 1, known as acyl-homoserine lactone. Here, we investigated the influence of autoinducer 1, N-dodecanoyl-homoserine lactone (C12-HSL) on the resistance of Salmonella enterica subspecies enterica serovar Enteritidis to nisin and acid stress. Salmonella cells growing in anaerobic tryptic soy agar (TSB) at a pH of 7.0 for 7 h were submitted to acid stress at a pH of 4.5 in the presence and absence of nisin and were either supplemented or not with C12-HSL. Viable cell counts, gene expression, membrane charge alterations, fatty acid composition, and intracellular content leakage were observed. The autoinducer C12-HSL increased nisin resistance and survival at a pH of 4.5 in Salmonella. Also, C12-HSL increased the expression of the genes, phoP, phoQ, pmrA, and pmrB, which are involved with antimicrobial and acid resistance. The positive charge on the cell surface and concentration of cyclopropane fatty acid of the cellular membrane were increased in the presence of C12-HSL under acidic conditions, whereas membrane fluidity decreased. The loss of K+ and NADPH, promoted by nisin, was reduced in the presence of C12-HSL at a pH of 4.5. Taken together, these findings suggest that quorum sensing plays an important role in enhanced nisin and acid resistance in Salmonella.
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Affiliation(s)
- Leonardo Luiz de Freitas
- Department of Microbiology, Universidade Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, MG, Brazil
| | | | - Deisy Guimarães Carneiro
- Department of Microbiology, Universidade Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, MG, Brazil
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The role of bacterial cell envelope structures in acid stress resistance in E. coli. Appl Microbiol Biotechnol 2020; 104:2911-2921. [PMID: 32067056 DOI: 10.1007/s00253-020-10453-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/29/2020] [Accepted: 02/07/2020] [Indexed: 12/14/2022]
Abstract
Acid resistance (AR) is an indispensable mechanism for the survival of neutralophilic bacteria, such as Escherichia coli (E. coli) strains that survive in the gastrointestinal tract. E. coli acid tolerance has been extensively studied during past decades, with most studies focused on gene regulation and mechanisms. However, the role of cell membrane structure in the context of acid stress resistance has not been discussed in depth. Here, we provide a comprehensive review of the roles and mechanisms of the E. coli cell envelope from different membrane components, such as membrane proteins, fatty acids, chaperones, and proton-consuming systems, and particularly focus on the innovative effects revealed by recent studies. We hope that the information guides us to understand the bacterial survival strategies under acid stress and to further explore the AR regulatory mechanisms to prevent or treat E. coli and other related Gram-negative bacteria infection, or to enhance the AR of engineering E. coli.
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40
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Azimi T, Zamirnasta M, Sani MA, Soltan Dallal MM, Nasser A. Molecular Mechanisms of Salmonella Effector Proteins: A Comprehensive Review. Infect Drug Resist 2020; 13:11-26. [PMID: 32021316 PMCID: PMC6954085 DOI: 10.2147/idr.s230604] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/20/2019] [Indexed: 12/27/2022] Open
Abstract
Salmonella can be categorized into many serotypes, which are specific to known hosts or broadhosts. It makes no difference which one of the serotypes would penetrate the gastrointestinal tract because they all face similar obstacles such as mucus and microbiome. However, following their penetration, some species remain in the gastrointestinal tract; yet, others spread to another organ like gallbladder. Salmonella is required to alter the immune response to sustain its intracellular life. Changing the host response requires particular effector proteins and vehicles to translocate them. To this end, a categorized gene called Salmonella pathogenicity island (SPI) was developed; genes like Salmonella pathogenicity island encode aggressive or modulating proteins. Initially, Salmonella needs to be attached and stabilized via adhesin factor, without which no further steps can be taken. In this review, an attempt has been made to elaborate on each factor attached to the host cell or to modulating and aggressive proteins that evade immune systems. This review includes four sections: (A) attachment factors or T3SS- independent entrance, (B) effector proteins or T3SS-dependent entrance, (c) regulation of invasive genes, and (D) regulation of immune responses.
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Affiliation(s)
- Taher Azimi
- Pediatric Infections Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Students Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Zamirnasta
- Clinical Microbiology Research Center, Ilam University of Medical Science, Ilam, Iran
| | - Mahmood Alizadeh Sani
- Food Safety and Hygiene Division, Environmental health Department, School of Public Health, Tehran University of medical sciences, Tehran, Iran
- Students Research Committee, Department of Food Sciences and Technology, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Ahmad Nasser
- Clinical Microbiology Research Center, Ilam University of Medical Science, Ilam, Iran
- Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Department of Medical Microbiology, School of Medicine, Ilam University of Medical Science, Ilam, Iran
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Desai SK, Kenney LJ. Switching Lifestyles Is an in vivo Adaptive Strategy of Bacterial Pathogens. Front Cell Infect Microbiol 2019; 9:421. [PMID: 31921700 PMCID: PMC6917575 DOI: 10.3389/fcimb.2019.00421] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/28/2019] [Indexed: 01/05/2023] Open
Abstract
Gram-positive and Gram-negative pathogens exist as planktonic cells only at limited times during their life cycle. In response to environmental signals such as temperature, pH, osmolality, and nutrient availability, pathogenic bacteria can adopt varied cellular fates, which involves the activation of virulence gene programs and/or the induction of a sessile lifestyle to form multicellular surface-attached communities. In Salmonella, SsrB is the response regulator which governs the lifestyle switch from an intracellular virulent state to form dormant biofilms in chronically infected hosts. Using the Salmonella lifestyle switch as a paradigm, we herein compare how other pathogens alter their lifestyles to enable survival, colonization and persistence in response to different environmental cues. It is evident that lifestyle switching often involves transcriptional regulators and their modification as highlighted here. Phenotypic heterogeneity resulting from stochastic cellular processes can also drive lifestyle variation among members of a population, although this subject is not considered in the present review.
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Affiliation(s)
- Stuti K. Desai
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Linda J. Kenney
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
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42
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Staes I, Passaris I, Cambré A, Aertsen A. Population heterogeneity tactics as driving force in Salmonella virulence and survival. Food Res Int 2019; 125:108560. [DOI: 10.1016/j.foodres.2019.108560] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 01/28/2023]
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43
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Petersen E, Miller SI. The cellular microbiology of Salmonellae interactions with macrophages. Cell Microbiol 2019; 21:e13116. [PMID: 31509644 DOI: 10.1111/cmi.13116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 09/06/2019] [Accepted: 09/10/2019] [Indexed: 12/27/2022]
Abstract
Salmonellae are important enteric pathogens that cause gastroenteritis and systemic illnesses. Macrophages are important components of both the innate and acquired immune system, acting as phagocytes with significant antimicrobial killing activities that present antigen to the adaptive immune system. Macrophages can also be cultured from a variety of sites as primary cells, and the study of the survival and interactions of Salmonellae with these cells is a very early model of infection and cellular microbiology. This review traces the history of discoveries made using Salmonellae infection of macrophages and addresses the possibility of future research in this area, in particular with regards to understanding the complexity of individual bacteria and macrophage cell variability and how such heterogeneity may alter the outcome of infection.
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Affiliation(s)
- Erik Petersen
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Samuel I Miller
- Department of Microbiology, University of Washington, Seattle, WA, USA.,Department of Immunology, University of Washington, Seattle, WA, USA.,Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Department of Medicine, University of Washington, Seattle, WA, USA
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Metabolic adaptability shifts of cell membrane fatty acids of Komagataeibacter hansenii HDM1-3 improve acid stress resistance and survival in acidic environments. J Ind Microbiol Biotechnol 2019; 46:1491-1503. [PMID: 31512094 DOI: 10.1007/s10295-019-02225-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 08/07/2019] [Indexed: 12/17/2022]
Abstract
Komagataeibacter hansenii HDM1-3 (K. hansenii HDM1-3) has been widely applied for producing bacterial cellulose (BC). The yield of BC has been frequently limited by the acidification during sugar metabolism, due to the generation of organic acids such as acetic acid. In this study, the acid resistance mechanism of K. hansenii HDM1-3 has been investigated from the aspect of metabolic adaptability of cell membrane fatty acids. Firstly, we observed that the survival rate of K. hansenii HDM1-3 was decreased with lowered pH values (adjusted with acetic acids), accompanied by increased leakage rate. Secondly, the cell membrane adaptability in response to acid stress was evaluated, including the variations of cell membrane fluidity and fatty acid composition. The proportion of unsaturated fatty acids was increased (especially, C18-1w9c and C19-Cyc), unsaturation degree and chain length of fatty acids were also increased. Thirdly, the potential molecular regulation mechanism was further elucidated. Under acid stress, the fatty acid synthesis pathway was involved in the structure and composition variations of fatty acids, which was proved by the activation of both fatty acid dehydrogenase (des) and cyclopropane fatty acid synthase (cfa) genes, as well as the addition of exogenous fatty acids. The fatty acid synthesis of K. hansenii HDM1-3 may be mediated by the activation of two-component sensor signaling pathways in response to the acid stress. The acid resistance mechanism of K. hansenii HDM1-3 adds to our knowledge of the acid stress adaptation, which may facilitate the development of new strategies for improving the industrial performance of this species under acid stress.
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Liew ATF, Foo YH, Gao Y, Zangoui P, Singh MK, Gulvady R, Kenney LJ. Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2. eLife 2019; 8:e45311. [PMID: 31033442 PMCID: PMC6557628 DOI: 10.7554/elife.45311] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/28/2019] [Indexed: 12/29/2022] Open
Abstract
After Salmonella is phagocytosed, it resides in an acidic vacuole. Its cytoplasm acidifies to pH 5.6; acidification activates pathogenicity island 2 (SPI-2). SPI-2 encodes a type three secretion system whose effectors modify the vacuole, driving endosomal tubulation. Using super-resolution imaging in single bacterial cells, we show that low pH induces expression of the SPI-2 SsrA/B signaling system. Single particle tracking, atomic force microscopy, and single molecule unzipping assays identified pH-dependent stimulation of DNA binding by SsrB. A so-called phosphomimetic form (D56E) was unable to bind to DNA in live cells. Acid-dependent DNA binding was not intrinsic to regulators, as PhoP and OmpR binding was not pH-sensitive. The low level of SPI-2 injectisomes observed in single cells is not due to fluctuating SsrB levels. This work highlights the surprising role that acid pH plays in virulence and intracellular lifestyles of Salmonella; modifying acid survival pathways represents a target for inhibiting Salmonella.
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Affiliation(s)
- Andrew Tze Fui Liew
- Mechanobiology Institute, T-LabNational University of SingaporeSingaporeSingapore
| | - Yong Hwee Foo
- Mechanobiology Institute, T-LabNational University of SingaporeSingaporeSingapore
| | - Yunfeng Gao
- Mechanobiology Institute, T-LabNational University of SingaporeSingaporeSingapore
| | - Parisa Zangoui
- Mechanobiology Institute, T-LabNational University of SingaporeSingaporeSingapore
| | | | - Ranjit Gulvady
- Mechanobiology Institute, T-LabNational University of SingaporeSingaporeSingapore
| | - Linda J Kenney
- Mechanobiology Institute, T-LabNational University of SingaporeSingaporeSingapore
- Biochemistry and Molecular BiologyUniversity of Texas Medical BranchGalvestonUnited States
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Koutsoumanis K, Allende A, Alvarez-Ordóñez A, Bolton D, Bover-Cid S, Chemaly M, De Cesare A, Herman L, Hilbert F, Lindqvist R, Nauta M, Peixe L, Ru G, Simmons M, Skandamis P, Suffredini E, Dewulf J, Hald T, Michel V, Niskanen T, Ricci A, Snary E, Boelaert F, Messens W, Davies R. Salmonella control in poultry flocks and its public health impact. EFSA J 2019; 17:e05596. [PMID: 32626222 PMCID: PMC7009056 DOI: 10.2903/j.efsa.2019.5596] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
An increase in confirmed human salmonellosis cases in the EU after 2014 triggered investigation of contributory factors and control options in poultry production. Reconsideration of the five current target serovars for breeding hens showed that there is justification for retaining Salmonella Enteritidis, Salmonella Typhimurium (including monophasic variants) and Salmonella Infantis, while Salmonella Virchow and Salmonella Hadar could be replaced by Salmonella Kentucky and either Salmonella Heidelberg, Salmonella Thompson or a variable serovar in national prevalence targets. However, a target that incorporates all serovars is expected to be more effective as the most relevant serovars in breeding flocks vary between Member State (MS) and over time. Achievement of a 1% target for the current target serovars in laying hen flocks is estimated to be reduced by 254,400 CrI95[98,540; 602,700] compared to the situation in 2016. This translates to a reduction of 53.4% CrI95[39.1; 65.7] considering the layer-associated human salmonellosis true cases and 6.2% considering the overall human salmonellosis true cases in the 23 MSs included in attribution modelling. A review of risk factors for Salmonella in laying hens revealed that overall evidence points to a lower occurrence in non-cage compared to cage systems. A conclusion on the effect of outdoor access or impact of the shift from conventional to enriched cages could not be reached. A similar review for broiler chickens concluded that the evidence that outdoor access affects the occurrence of Salmonella is inconclusive. There is conclusive evidence that an increased stocking density, larger farms and stress result in increased occurrence, persistence and spread of Salmonella in laying hen flocks. Based on scientific evidence, an impact of Salmonella control programmes, apart from general hygiene procedures, on the prevalence of Campylobacter in broiler flocks at the holding and on broiler meat at the end of the slaughter process is not expected.
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47
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De Silva PM, Kumar A. Signal Transduction Proteins in Acinetobacter baumannii: Role in Antibiotic Resistance, Virulence, and Potential as Drug Targets. Front Microbiol 2019; 10:49. [PMID: 30761101 PMCID: PMC6363711 DOI: 10.3389/fmicb.2019.00049] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/14/2019] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a notorious pathogen in health care settings around the world, primarily due to high resistance to antibiotics. A. baumannii also shows an impressive capability to adapt to harsh conditions in clinical settings, which contributes to its persistence in such conditions. Following their traditional role, the Two Component Systems (TCSs) present in A. baumannii play a crucial role in sensing and adapting to the changing environmental conditions. This provides A. baumannii with a greater chance of survival even in unfavorable conditions. Since all the TCSs characterized to date in A. baumannii play a role in its antibiotic resistance and virulence, understanding the underlying molecular mechanisms behind TCSs can help with a better understanding of the pathways that regulate these phenotypes. This can also guide efforts to target TCSs as novel drug targets. In this review, we discuss the roles of TCSs in A. baumannii, their molecular mechanisms, and most importantly, the potential of using small molecule inhibitors of TCSs as potential novel drug targets.
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Affiliation(s)
- P Malaka De Silva
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada.,Manitoba Chemosensory Biology Group, University of Manitoba, Winnipeg, MB, Canada
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