1
|
Raabis SM, Westerman TL, Cruz E, Deblois CL, Suen G, Elfenbein JR. Sensitivity of dairy calf Salmonella enterica serotype Cerro isolates to infection-relevant stressors. Microbiol Spectr 2024:e0021224. [PMID: 39145636 DOI: 10.1128/spectrum.00212-24] [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: 01/22/2024] [Accepted: 06/16/2024] [Indexed: 08/16/2024] Open
Abstract
Salmonella enterica serotype Cerro (S. Cerro) is an emerging Salmonella serotype isolated from cattle, but the association of S. Cerro with disease is not well understood. While comparative genomic analyses of bovine S. Cerro isolates have indicated mutations in elements associated with virulence, the correlation of S. Cerro fecal shedding with clinical disease in cattle varies between epidemiologic studies. The primary objective of this study was to characterize the infection-relevant phenotypes of S. Cerro fecal isolates obtained from neonatal calves born on a dairy farm in Wisconsin, USA. The S. Cerro isolates varied in biofilm production and sensitivity to the bile salt deoxycholate. All S. Cerro isolates were sensitive to sodium hypochlorite, hydrogen peroxide, and acidic shock. However, S. Cerro isolates were resistant to nitric oxide stress. Two S. Cerro isolates were unable to compete with S. Typhimurium during infection of calf ligated intestinal loops, indicating decreased fitness in vivo. Together, our data suggest that S. Cerro is sensitive to some innate antimicrobial defenses present in the gut, many of which are also used to control Salmonella in the environment. The observed phenotypic variation in S. Cerro isolates from a single farm suggest phenotypic plasticity that could impact infectious potential, transmission, and persistence on a farm.IMPORTANCESalmonella enterica is a zoonotic pathogen that threatens both human and animal health. Salmonella enterica serotype Cerro is being isolated from cattle at increasing frequency over the past two decades; however, its association with clinical disease is unclear. The goal of this study was to characterize infection-relevant phenotypes of S. Cerro isolates obtained from dairy calves from a single farm. Our work shows that there can be variation among temporally related S. Cerro isolates and that these isolates are sensitive to killing by toxic compounds of the innate immune system and those used for environmental control of Salmonella. This work contributes to our understanding of the pathogenic potential of the emerging pathogen S. Cerro.
Collapse
Affiliation(s)
- Sarah M Raabis
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Trina L Westerman
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Eddy Cruz
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Courtney L Deblois
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Bacteriology, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Garret Suen
- Department of Bacteriology, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Johanna R Elfenbein
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Food Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA
| |
Collapse
|
2
|
Saposnik L, Coria LM, Bruno L, Guaimas FF, Pandolfi J, Pol M, Urga ME, Sabbione F, McClelland M, Trevani A, Pasquevich KA, Cassataro J. Ecotin protects Salmonella Typhimurium against the microbicidal activity of host proteases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.15.594389. [PMID: 38798423 PMCID: PMC11118277 DOI: 10.1101/2024.05.15.594389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Salmonella enterica serovar Typhimurium causes acute diarrhea upon oral infection in humans. The harsh and proteolytic environment found in the gastrointestinal tract is the first obstacle that these bacteria face after infection. However, the mechanisms that allow Salmonella to survive the hostile conditions of the gut are poorly understood. The ecotin gene is found in an extensive range of known phyla of bacteria and it encodes a protein that has been shown to inhibit serine proteases. Thus, in the present work we studied the role of ecotin of Salmonella Typhimurium in host-pathogen interactions. We found that Salmonella Typhimurium Δ ecotin strain exhibited lower inflammation in a murine model of Salmonella induced colitis. The Δ ecotin mutant was more susceptible to the action of pancreatin and purified pancreatic elastase. In addition, the lack of ecotin led to impaired adhesion to Caco-2 and HT-29 cell lines, related to the proteolytic activity of brush border enzymes. Besides, Δ ecotin showed higher susceptibility to lysosomal proteolytic content and intracellular replication defects in macrophages. In addition, we found Ecotin to have a crucial role in Salmonella against the microbicide action of granules released and neutrophil extracellular traps from human polymorphonuclear leukocytes. Thus, the work presented here highlights the importance of ecotin in Salmonella as countermeasures against the host proteolytic defense system. IMPORTANCE The gastrointestinal tract is a very complex and harsh environment. Salmonella is a successful food borne pathogen, but little is known about its capacity to survive against the proteolysis of the gut lumen and intracellular proteases. Here, we show that Ecotin, a serine protease inhibitor, plays an important role in protecting Salmonella against proteases present at different sites encountered during oral infection. Our results indicate that Ecotin is an important virulence factor in Salmonella , adding another tool to the wide range of features this pathogen uses during oral infection.
Collapse
|
3
|
Seo B, Lee D, Jeon H, Ha J, Suh S. MotGen: a closed-loop bacterial motility control framework using generative adversarial networks. Bioinformatics 2024; 40:btae170. [PMID: 38552318 PMCID: PMC11031359 DOI: 10.1093/bioinformatics/btae170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/02/2024] [Accepted: 03/27/2024] [Indexed: 04/21/2024] Open
Abstract
MOTIVATION Many organisms' survival and behavior hinge on their responses to environmental signals. While research on bacteria-directed therapeutic agents has increased, systematic exploration of real-time modulation of bacterial motility remains limited. Current studies often focus on permanent motility changes through genetic alterations, restricting the ability to modulate bacterial motility dynamically on a large scale. To address this gap, we propose a novel real-time control framework for systematically modulating bacterial motility dynamics. RESULTS We introduce MotGen, a deep learning approach leveraging Generative Adversarial Networks to analyze swimming performance statistics of motile bacteria based on live cell imaging data. By tracking objects and optimizing cell trajectory mapping under environmentally altered conditions, we trained MotGen on a comprehensive statistical dataset derived from real image data. Our experimental results demonstrate MotGen's ability to capture motility dynamics from real bacterial populations with low mean absolute error in both simulated and real datasets. MotGen allows us to approach optimal swimming conditions for desired motility statistics in real-time. MotGen's potential extends to practical biomedical applications, including immune response prediction, by providing imputation of bacterial motility patterns based on external environmental conditions. Our short-term, in-situ interventions for controlling motility behavior offer a promising foundation for the development of bacteria-based biomedical applications. AVAILABILITY AND IMPLEMENTATION MotGen is presented as a combination of Matlab image analysis code and a machine learning workflow in Python. Codes are available at https://github.com/bgmseo/MotGen, for cell tracking and implementation of trained models to generate bacterial motility statistics.
Collapse
Affiliation(s)
- BoGeum Seo
- Department of Mechanical Engineering, Seoul National University, 08826 Seoul, Republic of Korea
| | - DoHee Lee
- Center for Healthcare Robotics, Korea Institute of Science & Technology, 02792 Seoul, Republic of Korea
| | - Heungjin Jeon
- Infection Control Convergence Research Center, Chungnam National University, 34134 Daejeon, Republic of Korea
| | - Junhyoung Ha
- Center for Healthcare Robotics, Korea Institute of Science & Technology, 02792 Seoul, Republic of Korea
| | - SeungBeum Suh
- Center for Healthcare Robotics, Korea Institute of Science & Technology, 02792 Seoul, Republic of Korea
| |
Collapse
|
4
|
Lamichhane B, Mawad AMM, Saleh M, Kelley WG, Harrington PJ, Lovestad CW, Amezcua J, Sarhan MM, El Zowalaty ME, Ramadan H, Morgan M, Helmy YA. Salmonellosis: An Overview of Epidemiology, Pathogenesis, and Innovative Approaches to Mitigate the Antimicrobial Resistant Infections. Antibiotics (Basel) 2024; 13:76. [PMID: 38247636 PMCID: PMC10812683 DOI: 10.3390/antibiotics13010076] [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: 11/21/2023] [Revised: 12/24/2023] [Accepted: 01/10/2024] [Indexed: 01/23/2024] Open
Abstract
Salmonella is a major foodborne pathogen and a leading cause of gastroenteritis in humans and animals. Salmonella is highly pathogenic and encompasses more than 2600 characterized serovars. The transmission of Salmonella to humans occurs through the farm-to-fork continuum and is commonly linked to the consumption of animal-derived food products. Among these sources, poultry and poultry products are primary contributors, followed by beef, pork, fish, and non-animal-derived food such as fruits and vegetables. While antibiotics constitute the primary treatment for salmonellosis, the emergence of antibiotic resistance and the rise of multidrug-resistant (MDR) Salmonella strains have highlighted the urgency of developing antibiotic alternatives. Effective infection management necessitates a comprehensive understanding of the pathogen's epidemiology and transmission dynamics. Therefore, this comprehensive review focuses on the epidemiology, sources of infection, risk factors, transmission dynamics, and the host range of Salmonella serotypes. This review also investigates the disease characteristics observed in both humans and animals, antibiotic resistance, pathogenesis, and potential strategies for treatment and control of salmonellosis, emphasizing the most recent antibiotic-alternative approaches for infection control.
Collapse
Affiliation(s)
- Bibek Lamichhane
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Asmaa M. M. Mawad
- Botany and Microbiology Department, Faculty of Science, Assiut University, Assiut 71516, Egypt
| | - Mohamed Saleh
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - William G. Kelley
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Patrick J. Harrington
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Cayenne W. Lovestad
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Jessica Amezcua
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Mohamed M. Sarhan
- Faculty of Pharmacy, King Salman International University (KSIU), Ras Sudr 8744304, Egypt
| | - Mohamed E. El Zowalaty
- Veterinary Medicine and Food Security Research Group, Medical Laboratory Sciences Program, Faculty of Health Sciences, Abu Dhabi Women’s Campus, Higher Colleges of Technology, Abu Dhabi 41012, United Arab Emirates
| | - Hazem Ramadan
- Hygiene and Zoonoses Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Melissa Morgan
- Department of Animal and Food Sciences, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Yosra A. Helmy
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| |
Collapse
|
5
|
Minamino T, Kinoshita M. Structure, Assembly, and Function of Flagella Responsible for Bacterial Locomotion. EcoSal Plus 2023; 11:eesp00112023. [PMID: 37260402 PMCID: PMC10729930 DOI: 10.1128/ecosalplus.esp-0011-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/14/2023] [Indexed: 01/28/2024]
Abstract
Many motile bacteria use flagella for locomotion under a variety of environmental conditions. Because bacterial flagella are under the control of sensory signal transduction pathways, each cell is able to autonomously control its flagellum-driven locomotion and move to an environment favorable for survival. The flagellum of Salmonella enterica serovar Typhimurium is a supramolecular assembly consisting of at least three distinct functional parts: a basal body that acts as a bidirectional rotary motor together with multiple force generators, each of which serves as a transmembrane proton channel to couple the proton flow through the channel with torque generation; a filament that functions as a helical propeller that produces propulsion; and a hook that works as a universal joint that transmits the torque produced by the rotary motor to the helical propeller. At the base of the flagellum is a type III secretion system that transports flagellar structural subunits from the cytoplasm to the distal end of the growing flagellar structure, where assembly takes place. In recent years, high-resolution cryo-electron microscopy (cryoEM) image analysis has revealed the overall structure of the flagellum, and this structural information has made it possible to discuss flagellar assembly and function at the atomic level. In this article, we describe what is known about the structure, assembly, and function of Salmonella flagella.
Collapse
Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Miki Kinoshita
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| |
Collapse
|
6
|
Leesombun A, Sungpradit S, Sariya L, Taowan J, Boonmasawai S. Transcriptional Profiling of the Effect of Coleus amboinicus L. Essential Oil against Salmonella Typhimurium Biofilm Formation. Antibiotics (Basel) 2023; 12:1598. [PMID: 37998800 PMCID: PMC10668763 DOI: 10.3390/antibiotics12111598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023] Open
Abstract
Salmonella enterica serovar Typhimurium cause infections primarily through foodborne transmission and remains a significant public health concern. The biofilm formation of this bacteria also contributes to their multidrug-resistant nature. Essential oils from medicinal plants are considered potential alternatives to conventional antibiotics. Therefore, this study assessed the antimicrobial and antibiofilm activities of Coleus amboinicus essential oil (EO-CA) against S. Typhimurium ATCC 14028. Seventeen chemical compounds of EO-CA were identified, and carvacrol (38.26%) was found to be the main constituent. The minimum inhibitory concentration (MIC) of EO-CA for S. Typhimurium planktonic growth was 1024 µg/mL while the minimum bactericidal concentration was 1024 µg/mL. EO-CA at sub-MIC (≥1/16× MIC) exhibited antibiofilm activity against the prebiofilm formation of S. Typhimurium at 24 h. Furthermore, EO-CA (≥1/4× MIC) inhibited postbiofilm formation at 24 and 48 h (p < 0.05). Transcriptional profiling revealed that the EO-CA-treated group at 1/2× MIC had 375 differentially expressed genes (DEGs), 106 of which were upregulated and 269 were downregulated. Five significantly downregulated virulent DEGs responsible for motility (flhD, fljB, and fimD), curli fimbriae (csgD), and invasion (hilA) were screened via quantitative reverse transcription PCR (qRT-PCR). This study suggests the potential of EO-CA as an effective antimicrobial agent for combating planktonic and biofilm formation of Salmonella.
Collapse
Affiliation(s)
- Arpron Leesombun
- Department of Pre-Clinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand; (A.L.); (S.S.)
| | - Sivapong Sungpradit
- Department of Pre-Clinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand; (A.L.); (S.S.)
| | - Ladawan Sariya
- The Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic Animals (MoZWE), Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand; (L.S.); (J.T.)
| | - Jarupha Taowan
- The Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic Animals (MoZWE), Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand; (L.S.); (J.T.)
| | - Sookruetai Boonmasawai
- Department of Pre-Clinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand; (A.L.); (S.S.)
| |
Collapse
|
7
|
Burciaga S, Trachsel JM, Sockett D, Aulik N, Monson MS, Anderson CL, Bearson SMD. Genomic and phenotypic comparison of two variants of multidrug-resistant Salmonella enterica serovar Heidelberg isolated during the 2015-2017 multi-state outbreak in cattle. Front Microbiol 2023; 14:1282832. [PMID: 37928690 PMCID: PMC10623430 DOI: 10.3389/fmicb.2023.1282832] [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: 08/24/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023] Open
Abstract
Salmonella enterica subspecies enterica serovar Heidelberg (Salmonella Heidelberg) has caused several multistate foodborne outbreaks in the United States, largely associated with the consumption of poultry. However, a 2015-2017 multidrug-resistant (MDR) Salmonella Heidelberg outbreak was linked to contact with dairy beef calves. Traceback investigations revealed calves infected with outbreak strains of Salmonella Heidelberg exhibited symptoms of disease frequently followed by death from septicemia. To investigate virulence characteristics of Salmonella Heidelberg as a pathogen in bovine, two variants with distinct pulse-field gel electrophoresis (PFGE) patterns that differed in morbidity and mortality during the multistate outbreak were genotypically and phenotypically characterized and compared. Strain SX 245 with PFGE pattern JF6X01.0523 was identified as a dominant and highly pathogenic variant causing high morbidity and mortality in affected calves, whereas strain SX 244 with PFGE pattern JF6X01.0590 was classified as a low pathogenic variant causing less morbidity and mortality. Comparison of whole-genome sequences determined that SX 245 lacked ~200 genes present in SX 244, including genes associated with the IncI1 plasmid and phages; SX 244 lacked eight genes present in SX 245 including a second YdiV Anti-FlhC(2)FlhD(4) factor, a lysin motif domain containing protein, and a pentapeptide repeat protein. RNA-sequencing revealed fimbriae-related, flagella-related, and chemotaxis genes had increased expression in SX 245 compared to SX 244. Furthermore, SX 245 displayed higher invasion of human and bovine epithelial cells than SX 244. These data suggest that the presence and up-regulation of genes involved in type 1 fimbriae production, flagellar regulation and biogenesis, and chemotaxis may play a role in the increased pathogenicity and host range expansion of the Salmonella Heidelberg isolates involved in the bovine-related outbreak.
Collapse
Affiliation(s)
- Selma Burciaga
- United States Department of Agriculture, Agriculture Research Services, National Animal Disease Center, Ames, IA, United States
- Oak Ridge Institute for Science and Education (ORISE), ARS Research Participation Program, Oak Ridge, TN, United States
| | - Julian M. Trachsel
- United States Department of Agriculture, Agriculture Research Services, National Animal Disease Center, Ames, IA, United States
| | - Donald Sockett
- Wisconsin Veterinary Diagnostic Laboratory, University of Wisconsin, Madison, WI, United States
| | - Nicole Aulik
- Wisconsin Veterinary Diagnostic Laboratory, University of Wisconsin, Madison, WI, United States
| | - Melissa S. Monson
- United States Department of Agriculture, Agriculture Research Services, National Animal Disease Center, Ames, IA, United States
| | - Christopher L. Anderson
- United States Department of Agriculture, Agriculture Research Services, National Animal Disease Center, Ames, IA, United States
| | - Shawn M. D. Bearson
- United States Department of Agriculture, Agriculture Research Services, National Animal Disease Center, Ames, IA, United States
| |
Collapse
|
8
|
Sultan M, Arya R, Chaurasia AK, Kim KK. Sensor histidine kinases kdpD and aauS regulate biofilm and virulence in Pseudomonas aeruginosa PA14. Front Cell Infect Microbiol 2023; 13:1270667. [PMID: 37881370 PMCID: PMC10595159 DOI: 10.3389/fcimb.2023.1270667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/25/2023] [Indexed: 10/27/2023] Open
Abstract
Pseudomonas aeruginosa is a multidrug-resistant opportunistic human pathogen that utilizes two-component systems (TCSs) to sense pathophysiological signals and coordinate virulence. P. aeruginosa contains 64 sensor histidine kinases (HKs) and 72 response regulators (RRs) that play important roles in metabolism, bacterial physiology, and virulence. However, the role of some TCSs in virulence remains uncharacterized. In this study, we evaluated the virulence potential of some uncharacterized sensor HK and RR knockouts in P. aeruginosa using a Galleria mellonella infection model. Furthermore, we demonstrated that KdpD and AauS HKs regulate virulence by affecting P. aeruginosa biofilm formation and motility. Both ΔkdpD and ΔaauS showed reduced biofilm and motility which were confirmed by restored phenotypes upon complementation. Moreover, ΔkdpD and ΔaauS exhibited increased survival of HeLa cells and G. mellonella during in vivo infection. Altered expression of the transcriptional regulators anR and lasR, along with the virulence genes lasA, pelA, cupA, pqsA, pqsB, pqsC, and pqsD in the mutant strains elucidated the mechanism by which ΔkdpD and ΔaauS affect virulence. These findings confirm that kdpD and aauS play important roles in P. aeruginosa pathogenesis by regulating biofilm formation and motility.
Collapse
Affiliation(s)
- Maria Sultan
- Department of Precision Medicine, Graduate School of Basic Medical Science, Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Rekha Arya
- Department of Precision Medicine, Graduate School of Basic Medical Science, Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Department of Orthopedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Akhilesh Kumar Chaurasia
- Department of Precision Medicine, Graduate School of Basic Medical Science, Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science, Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| |
Collapse
|
9
|
Saleh DO, Horstmann JA, Giralt-Zúñiga M, Weber W, Kaganovitch E, Durairaj AC, Klotzsch E, Strowig T, Erhardt M. SPI-1 virulence gene expression modulates motility of Salmonella Typhimurium in a proton motive force- and adhesins-dependent manner. PLoS Pathog 2023; 19:e1011451. [PMID: 37315106 DOI: 10.1371/journal.ppat.1011451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/01/2023] [Indexed: 06/16/2023] Open
Abstract
Both the bacterial flagellum and the evolutionary related injectisome encoded on the Salmonella pathogenicity island 1 (SPI-1) play crucial roles during the infection cycle of Salmonella species. The interplay of both is highlighted by the complex cross-regulation that includes transcriptional control of the flagellar master regulatory operon flhDC by HilD, the master regulator of SPI-1 gene expression. Contrary to the HilD-dependent activation of flagellar gene expression, we report here that activation of HilD resulted in a dramatic loss of motility, which was dependent on the presence of SPI-1. Single cell analyses revealed that HilD-activation triggers a SPI-1-dependent induction of the stringent response and a substantial decrease in proton motive force (PMF), while flagellation remains unaffected. We further found that HilD activation enhances the adhesion of Salmonella to epithelial cells. A transcriptome analysis revealed a simultaneous upregulation of several adhesin systems, which, when overproduced, phenocopied the HilD-induced motility defect. We propose a model where the SPI-1-dependent depletion of the PMF and the upregulation of adhesins upon HilD-activation enable flagellated Salmonella to rapidly modulate their motility during infection, thereby enabling efficient adhesion to host cells and delivery of effector proteins.
Collapse
Affiliation(s)
- Doaa Osama Saleh
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Julia A Horstmann
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - María Giralt-Zúñiga
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Willi Weber
- Institute for Biology, Experimental Biophysics/Mechanobiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Eugen Kaganovitch
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Abilash Chakravarthy Durairaj
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Department of Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Enrico Klotzsch
- Institute for Biology, Experimental Biophysics/Mechanobiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Till Strowig
- Department of Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Marc Erhardt
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| |
Collapse
|
10
|
Flagellar Phenotypes Impact on Bacterial Transport and Deposition Behavior in Porous Media: Case of Salmonella enterica Serovar Typhimurium. Int J Mol Sci 2022; 23:ijms232214460. [PMID: 36430938 PMCID: PMC9698738 DOI: 10.3390/ijms232214460] [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: 10/06/2022] [Revised: 11/11/2022] [Accepted: 11/16/2022] [Indexed: 11/23/2022] Open
Abstract
Bacterial contamination of groundwater has always been an ecological problem worthy of attention. In this study, Salmonella enterica serovar Typhimurium with different flagellar phenotypes mainly characterized during host-pathogen interaction were analyzed for their transport and deposition behavior in porous media. Column transport experiments and a modified mobile-immobile model were applicated on different strains with flagellar motility (wild-type) or without motility (ΔmotAB), without flagella (ΔflgKL), methylated and unmethylated flagellin (ΔfliB), and different flagella phases (fliCON, fljBON). Results showed that flagella motility could promote bacterial transport and deposition due to their biological advantages of moving and attaching to surfaces. We also found that the presence of non-motile flagella improved bacterial adhesion according to a higher retention rate of the ΔmotAB strain compared to the ΔflgKL strain. This indicated that bacteria flagella and motility both had promoting effects on bacterial deposition in sandy porous media. Flagella phases influenced the bacterial movement; the fliCON strain went faster through the column than the fljBON strain. Moreover, flagella methylation was found to favor bacterial transport and deposition. Overall, flagellar modifications affect Salmonella enterica serovar Typhimurium transport and deposition behavior in different ways in environmental conditions.
Collapse
|
11
|
Wang H, Tang Z, Xue B, Lu Q, Liu X, Zou Q. Salmonella Regulator STM0347 Mediates Flagellar Phase Variation via Hin Invertase. Int J Mol Sci 2022; 23:ijms23158481. [PMID: 35955615 PMCID: PMC9368917 DOI: 10.3390/ijms23158481] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 12/04/2022] Open
Abstract
Salmonella enterica is one of the most important food-borne pathogens, whose motility and virulence are highly related to flagella. Flagella alternatively express two kinds of surface antigen flagellin, FliC and FljB, in a phenomenon known as flagellar phase variation. The molecular mechanisms by which the switching orientation of the Hin-composed DNA segment mediates the expression of the fljBA promoter have been thoroughly illustrated. However, the precise regulators that control DNA strand exchange are barely understood. In this study, we found that a putative response regulator, STM0347, contributed to the phase variation of flagellin in S. Typhimurium. With quantitative proteomics and secretome profiling, a lack of STM0347 was confirmed to induce the transformation of flagellin from FliC to FljB. Real-time PCR and in vitro incubation of SMT0347 with the hin DNA segment suggested that STM0347 disturbed Hin-catalyzed DNA reversion via hin degradation, and the overexpression of Hin was sufficient to elicit flagellin variation. Subsequently, the Δstm0347 strain was outcompeted by its parental strain in HeLa cell invasion. Collectively, our results reveal the crucial role of STM0347 in Salmonella virulence and flagellar phase variation and highlight the complexity of the regulatory network of Hin-modulated flagellum phase variation in Salmonella.
Collapse
Affiliation(s)
- Hongou Wang
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (H.W.); (Z.T.); (Q.L.)
| | - Zhiheng Tang
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (H.W.); (Z.T.); (Q.L.)
| | - Baoshuai Xue
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130012, China;
| | - Qinghui Lu
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (H.W.); (Z.T.); (Q.L.)
| | - Xiaoyun Liu
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (H.W.); (Z.T.); (Q.L.)
- Correspondence: (X.L.); (Q.Z.); Tel.: +86-10-82805673 (X.L.); +86-10-8280-5070 (Q.Z.)
| | - Qinghua Zou
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (H.W.); (Z.T.); (Q.L.)
- Correspondence: (X.L.); (Q.Z.); Tel.: +86-10-82805673 (X.L.); +86-10-8280-5070 (Q.Z.)
| |
Collapse
|
12
|
Fatty Acid Homeostasis Tunes Flagellar Motility by Activating Phase 2 Flagellin Expression, Contributing to Salmonella Gut Colonization. Infect Immun 2022; 90:e0018422. [PMID: 35652649 DOI: 10.1128/iai.00184-22] [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: 11/20/2022] Open
Abstract
Long-chain-fatty-acid (LCFA) metabolism is a fundamental cellular process in bacteria that is involved in lipid homeostasis, energy production, and infection. However, the role of LCFA metabolism in Salmonella enterica serovar Typhimurium (S. Tm) gut infection remains unclear. Here, using a murine gastroenteritis infection model, we demonstrate involvement of LCFA metabolism in S. Tm gut colonization. The LCFA metabolism-associated transcriptional regulator FadR contributes to S. Tm gut colonization. fadR deletion alters the gene expression profile and leads to aberrant flagellar motility of S. Tm. Colonization defects in the fadR mutant are attributable to altered swimming behavior characterized by less frequently smooth swimming, resulting from reduced expression of the phase 2 flagellin FljB. Notably, changes in lipid LCFA composition by fadR deletion lead to reduced expression of fljB, which is restored by exogenous LCFA. Therefore, LCFA homeostasis may maintain proper flagellar motility by activating fljB expression, contributing to S. Tm gut colonization. Our findings improve the understanding of the effect of luminal LCFA on the virulence of enteric pathogens.
Collapse
|
13
|
Cohen H, Hoede C, Scharte F, Coluzzi C, Cohen E, Shomer I, Mallet L, Holbert S, Serre RF, Schiex T, Virlogeux-Payant I, Grassl GA, Hensel M, Chiapello H, Gal-Mor O. Intracellular Salmonella Paratyphi A is motile and differs in the expression of flagella-chemotaxis, SPI-1 and carbon utilization pathways in comparison to intracellular S. Typhimurium. PLoS Pathog 2022; 18:e1010425. [PMID: 35381053 PMCID: PMC9012535 DOI: 10.1371/journal.ppat.1010425] [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: 10/18/2021] [Revised: 04/15/2022] [Accepted: 03/09/2022] [Indexed: 12/21/2022] Open
Abstract
Although Salmonella Typhimurium (STM) and Salmonella Paratyphi A (SPA) belong to the same phylogenetic species, share large portions of their genome and express many common virulence factors, they differ vastly in their host specificity, the immune response they elicit, and the clinical manifestations they cause. In this work, we compared their intracellular transcriptomic architecture and cellular phenotypes during human epithelial cell infection. While transcription induction of many metal transport systems, purines, biotin, PhoPQ and SPI-2 regulons was similar in both intracellular SPA and STM, we identified 234 differentially expressed genes that showed distinct expression patterns in intracellular SPA vs. STM. Surprisingly, clear expression differences were found in SPI-1, motility and chemotaxis, and carbon (mainly citrate, galactonate and ethanolamine) utilization pathways, indicating that these pathways are regulated differently during their intracellular phase. Concurring, on the cellular level, we show that while the majority of STM are non-motile and reside within Salmonella-Containing Vacuoles (SCV), a significant proportion of intracellular SPA cells are motile and compartmentalized in the cytosol. Moreover, we found that the elevated expression of SPI-1 and motility genes by intracellular SPA results in increased invasiveness of SPA, following exit from host cells. These findings demonstrate unexpected flagellum-dependent intracellular motility of a typhoidal Salmonella serovar and intriguing differences in intracellular localization between typhoidal and non-typhoidal salmonellae. We propose that these differences facilitate new cycles of host cell infection by SPA and may contribute to the ability of SPA to disseminate beyond the intestinal lamina propria of the human host during enteric fever. Salmonella enterica is a ubiquitous, facultative intracellular animal and human pathogen. Although non-typhoidal Salmonella (NTS) and typhoidal Salmonella serovars belong to the same phylogenetic species and share many virulence factors, the disease they cause in humans is very different. While the underlying mechanisms for these differences are not fully understood, one possible reason expected to contribute to their different pathogenicity is a distinct expression pattern of genes involved in host-pathogen interactions. Here, we compared the global gene expression and intracellular phenotypes, during human epithelial cell infection of S. Paratyphi A (SPA) and S. Typhimurium (STM), as prototypical serovars of typhoidal and NTS, respectively. Interestingly, we identified different expression patterns in key virulence and metabolic pathways, cytosolic motility and increased reinvasion of SPA, following exit from infected cells. We hypothesize that these differences contribute to the invasive and systemic disease developed following SPA infection in humans.
Collapse
Affiliation(s)
- Helit Cohen
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
| | - Claire Hoede
- Université Fédérale de Toulouse, INRAE, BioinfOmics, UR MIAT, GenoToul Bioinformatics facility, 31326, Castanet-Tolosan, France
| | - Felix Scharte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Charles Coluzzi
- INRAE, Université Paris-Saclay, MaIAGE, Jouy-en-Josas, France
| | - Emiliano Cohen
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
| | - Inna Shomer
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
| | - Ludovic Mallet
- Université Fédérale de Toulouse, INRAE, BioinfOmics, UR MIAT, GenoToul Bioinformatics facility, 31326, Castanet-Tolosan, France
| | | | | | - Thomas Schiex
- Université Fédérale de Toulouse, ANITI, INRAE, Toulouse, France
| | | | - Guntram A. Grassl
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School and German Center for Infection Research (DZIF), Hanover, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs–Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Osnabrück, Germany
- * E-mail: (MH); (HC); (OG-M)
| | - Hélène Chiapello
- Université Fédérale de Toulouse, INRAE, BioinfOmics, UR MIAT, GenoToul Bioinformatics facility, 31326, Castanet-Tolosan, France
- INRAE, Université Paris-Saclay, MaIAGE, Jouy-en-Josas, France
- * E-mail: (MH); (HC); (OG-M)
| | - Ohad Gal-Mor
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- * E-mail: (MH); (HC); (OG-M)
| |
Collapse
|
14
|
Ek V, Fattinger SA, Florbrant A, Hardt WD, Di Martino ML, Eriksson J, Sellin ME. A Motile Doublet Form of Salmonella Typhimurium Diversifies Target Search Behaviour at the Epithelial Surface. Mol Microbiol 2022; 117:1156-1172. [PMID: 35332598 PMCID: PMC9325389 DOI: 10.1111/mmi.14898] [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: 11/04/2021] [Revised: 02/24/2022] [Accepted: 03/21/2022] [Indexed: 12/01/2022]
Abstract
The behaviors of infectious bacteria are commonly studied in bulk. This is effective to define the general properties of a given isolate, but insufficient to resolve subpopulations and unique single‐microbe behaviors within the bacterial pool. We here employ microscopy to study single‐bacterium characteristics among Salmonella enterica serovar Typhimurium (S.Tm), as they prepare for and launch invasion of epithelial host cells. We find that during the bacterial growth cycle, S.Tm populations switch gradually from fast planktonic growth to a host cell‐invasive phenotype, characterized by flagellar motility and expression of the Type‐three‐secretion‐system‐1. The indistinct nature of this shift leads to the establishment of a transient subpopulation of S.Tm “doublets”—waist‐bearing bacteria anticipating cell division—which simultaneously express host cell invasion machinery. In epithelial cell culture infections, these S.Tm doublets outperform their “singlet” brethren and represent a hyperinvasive subpopulation. Atop both glass and enteroid‐derived monolayers, doublets swim along markedly straighter trajectories than singlets, thereby diversifying search patterns and improving the surface exploration capacity of the total bacterial population. The straighter swimming, combined with an enhanced cell‐adhesion propensity, suffices to account for the hyperinvasive doublet phenotype. This work highlights bacterial cell length heterogeneity as a key determinant of target search patterns atop epithelia.
Collapse
Affiliation(s)
- Viktor Ek
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Stefan A Fattinger
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden.,Institute of Microbiology, Department of Biology, ETH, Zurich, Zurich, Switzerland
| | - Alexandra Florbrant
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH, Zurich, Zurich, Switzerland
| | - Maria Letizia Di Martino
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Jens Eriksson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| |
Collapse
|
15
|
The battle for oxygen during bacterial and fungal infections. Trends Microbiol 2022; 30:643-653. [DOI: 10.1016/j.tim.2022.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/07/2022] [Accepted: 01/10/2022] [Indexed: 12/22/2022]
|
16
|
Flagellin lysine methyltransferase FliB catalyzes a [4Fe-4S] mediated methyl transfer reaction. PLoS Pathog 2021; 17:e1010052. [PMID: 34788341 PMCID: PMC8598068 DOI: 10.1371/journal.ppat.1010052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/20/2021] [Indexed: 11/19/2022] Open
Abstract
The methyltransferase FliB posttranslationally modifies surface-exposed ɛ-N-lysine residues of flagellin, the protomer of the flagellar filament in Salmonella enterica (S. enterica). Flagellin methylation, reported originally in 1959, was recently shown to enhance host cell adhesion and invasion by increasing the flagellar hydrophobicity. The role of FliB in this process, however, remained enigmatic. In this study, we investigated the properties and mechanisms of FliB from S. enterica in vivo and in vitro. We show that FliB is an S-adenosylmethionine (SAM) dependent methyltransferase, forming a membrane associated oligomer that modifies flagellin in the bacterial cytosol. Using X-band electron paramagnetic resonance (EPR) spectroscopy, zero-field 57Fe Mössbauer spectroscopy, methylation assays and chromatography coupled mass spectrometry (MS) analysis, we further found that FliB contains an oxygen sensitive [4Fe-4S] cluster that is essential for the methyl transfer reaction and might mediate a radical mechanism. Our data indicate that the [4Fe-4S] cluster is coordinated by a cysteine rich motif in FliB that is highly conserved among multiple genera of the Enterobacteriaceae family.
Collapse
|
17
|
Lang M, Montjarret A, Duteil E, Bedoux G. Cinnamomum cassia and Syzygium aromaticum Essential Oils Reduce the Colonization of Salmonella Typhimurium in an In Vivo Infection Model Using Caenorhabditis elegans. Molecules 2021; 26:5598. [PMID: 34577068 PMCID: PMC8467367 DOI: 10.3390/molecules26185598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
The regulation of intestinal colonization in livestock by means of non-bactericidal additives is an important management lever for zoonotic bacteria such as Salmonella spp. Caenorhabditis elegans is proposed here as a model for the evaluation of five essential oils (EOs) as anti-colonization products against Salmonella Typhimurium. An evaluation of the toxicity of EOs for C. elegans showed LD50 values ranging from 74.5 ± 9.6 µg/mL for Cinnamomum cassia (CEO) to 271.6 ± 14.9 µg/mL for Syzygium aromaticum (SyEO). Both EOs significantly inhibited bacterial colonization in the digestive tract of C. elegans with reductions of 0.88 and 0.70 log CFU/nematode at nontoxic concentrations of 50 µg/mL and 150 µg/mL, respectively. With the minimal bactericidal concentrations of CEO and SyEO against S. Typhimurium being 312.5 µg/mL and 625 µg/mL, respectively, an antibacterial effect can be excluded to explain the inhibition of the bacterial load. The anti-colonizing activity of these two EOs could, however, be related to an inhibition of the swimming motility, which was significantly reduced by 23.47% for CEO at 50 µg/mL and 19.56% for SyEO at 150 µg/mL. This study shows the potential of C. elegans as a predictive in vivo model of anti-colonizing activities that is suitable for the evaluation of essential oils.
Collapse
Affiliation(s)
- Marie Lang
- BioArmor S.A., Z.I de la Gare, F-22940 Plaintel, France; (A.M.); (E.D.)
- Laboratoire de Biotechnologie et Chimie Marines EA 3884, Université Bretagne Sud, F-56100 Lorient, France;
| | - Aude Montjarret
- BioArmor S.A., Z.I de la Gare, F-22940 Plaintel, France; (A.M.); (E.D.)
| | - Emmanuel Duteil
- BioArmor S.A., Z.I de la Gare, F-22940 Plaintel, France; (A.M.); (E.D.)
| | - Gilles Bedoux
- Laboratoire de Biotechnologie et Chimie Marines EA 3884, Université Bretagne Sud, F-56100 Lorient, France;
| |
Collapse
|
18
|
Fattinger SA, Sellin ME, Hardt WD. Salmonella effector driven invasion of the gut epithelium: breaking in and setting the house on fire. Curr Opin Microbiol 2021; 64:9-18. [PMID: 34492596 DOI: 10.1016/j.mib.2021.08.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/10/2021] [Accepted: 08/17/2021] [Indexed: 12/15/2022]
Abstract
Salmonella Typhimurium (S.Tm) is a major cause of diarrheal disease. The invasion into intestinal epithelial cells (IECs) is a central step in the infection cycle. It is associated with gut inflammation and thought to benefit S.Tm proliferation also in the intestinal lumen. Importantly, it is still not entirely clear how inflammation is elicited and to which extent it links to IEC invasion efficiency in vivo. In this review, we summarize recent findings explaining IEC invasion by type-three-secretion-system-1 (TTSS-1) effector proteins and discuss their effects on invasion and gut inflammation. In non-polarized tissue culture cells, the TTSS-1 effectors (mainly SopB/E/E2) elicit large membrane ruffles fueling cooperative invasion, and can directly trigger pro-inflammatory signaling. By contrast, in the murine gut, we observe discreet-invasion (mainly via the TTSS-1 effector SipA) and a prominent pro-inflammatory role of the host?"s epithelial inflammasome(s), which sense pathogen associated molecular patterns (PAMPs). We discuss why it has remained a major challenge to tease apart direct and indirect inflammatory effects of TTSS-1 effectors and explain why further research will be needed to fully determine their inflammation-modulating role(s).
Collapse
Affiliation(s)
- Stefan A Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland; Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
| |
Collapse
|
19
|
Bacterial Flagellar Filament: A Supramolecular Multifunctional Nanostructure. Int J Mol Sci 2021; 22:ijms22147521. [PMID: 34299141 PMCID: PMC8306008 DOI: 10.3390/ijms22147521] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/06/2021] [Accepted: 07/10/2021] [Indexed: 02/07/2023] Open
Abstract
The bacterial flagellum is a complex and dynamic nanomachine that propels bacteria through liquids. It consists of a basal body, a hook, and a long filament. The flagellar filament is composed of thousands of copies of the protein flagellin (FliC) arranged helically and ending with a filament cap composed of an oligomer of the protein FliD. The overall structure of the filament core is preserved across bacterial species, while the outer domains exhibit high variability, and in some cases are even completely absent. Flagellar assembly is a complex and energetically costly process triggered by environmental stimuli and, accordingly, highly regulated on transcriptional, translational and post-translational levels. Apart from its role in locomotion, the filament is critically important in several other aspects of bacterial survival, reproduction and pathogenicity, such as adhesion to surfaces, secretion of virulence factors and formation of biofilms. Additionally, due to its ability to provoke potent immune responses, flagellins have a role as adjuvants in vaccine development. In this review, we summarize the latest knowledge on the structure of flagellins, capping proteins and filaments, as well as their regulation and role during the colonization and infection of the host.
Collapse
|
20
|
High-Definition DIC Imaging Uncovers Transient Stages of Pathogen Infection Cycles on the Surface of Human Adult Stem Cell-Derived Intestinal Epithelium. mBio 2021; 13:e0002222. [PMID: 35100876 PMCID: PMC8805028 DOI: 10.1128/mbio.00022-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Interactions between individual pathogenic microbes and host tissues involve fast and dynamic processes that ultimately impact the outcome of infection. Using live-cell microscopy, these dynamics can be visualized to study, e.g., microbe motility, binding and invasion of host cells, and intrahost-cell survival. Such methodology typically employs confocal imaging of fluorescent tags in tumor-derived cell line infections on glass. This allows high-definition imaging but poorly reflects the host tissue's physiological architecture and may result in artifacts. We developed a method for live-cell imaging of microbial infection dynamics on human adult stem cell-derived intestinal epithelial cell (IEC) layers. These IEC layers are grown in apical imaging chambers, optimized for physiological cell arrangement and fast, but gentle, differential interference contrast (DIC) imaging. This allows subsecond visualization of both microbial and epithelial surface ultrastructure at high resolution without using fluorescent reporters. We employed this technology to probe the behavior of two model pathogens, Salmonella enterica serovar Typhimurium and Giardia intestinalis, at the intestinal epithelial surface. Our results reveal pathogen-specific swimming patterns on the epithelium and show that Salmonella lingers on the IEC surface for prolonged periods before host cell invasion, while Giardia uses circular swimming with intermittent attachments to scout for stable adhesion sites. The method even permits tracking of individual Giardia flagella, demonstrating that active flagellar beating and attachment to the IEC surface are not mutually exclusive. This work describes a generalizable and relatively inexpensive approach to resolving dynamic pathogen-IEC layer interactions, applicable even to genetically nontractable microorganisms. IMPORTANCE Knowledge of dynamic niche-specific interactions between single microbes and host cells is essential to understand infectious disease progression. However, advances in this field have been hampered by the inherent conflict between the technical requirements for high-resolution live-cell imaging on the one hand and conditions that best mimic physiological infection niche parameters on the other. Toward bridging this divide, we present a methodology for differential interference contrast (DIC) imaging of pathogen interactions at the apical surface of enteroid-derived intestinal epithelia, providing both high spatial and temporal resolution. This alleviates the need for fluorescent reporters in live-cell imaging and provides dynamic information about microbe interactions with a nontransformed, confluent, polarized, and microvilliated human gut epithelium. Using this methodology, we uncover previously unrecognized stages of Salmonella and Giardia infection cycles at the epithelial surface.
Collapse
|
21
|
Salmonella enterica Serovar Typhimurium Exploits Cycling through Epithelial Cells To Colonize Human and Murine Enteroids. mBio 2021; 12:mBio.02684-20. [PMID: 33436434 PMCID: PMC7844539 DOI: 10.1128/mbio.02684-20] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Enterobacterial pathogens infect the gut by a multistep process, resulting in colonization of both the lumen and the mucosal epithelium. Due to experimental constraints, it remains challenging to address how luminal and epithelium-lodged pathogen populations cross-feed each other in vivo Enteroids are cultured three-dimensional miniature intestinal organs with a single layer of primary intestinal epithelial cells (IECs) surrounding a central lumen. They offer new opportunities to study enterobacterial infection under near-physiological conditions, at a temporal and spatial resolution not attainable in animal models, but remain poorly explored in this context. We employed microinjection, time-lapse microscopy, bacterial genetics, and barcoded consortium infections to describe the complete infection cycle of Salmonella enterica serovar Typhimurium in both human and murine enteroids. Flagellar motility and type III secretion system 1 (TTSS-1) promoted Salmonella Typhimurium targeting of the intraepithelial compartment and breaching of the epithelial barrier. Strikingly, however, TTSS-1 also potently boosted colonization of the enteroid lumen. By tracing the infection over time, we identified a cycle(s) of TTSS-1-driven IEC invasion, intraepithelial replication, and reemergence through infected IEC expulsion as a key mechanism for Salmonella Typhimurium luminal colonization. These findings suggest a positive feed-forward loop, through which IEC invasion by planktonic bacteria fuels further luminal population expansion, thereby ensuring efficient colonization of both the intraepithelial and luminal niches.IMPORTANCE Pathogenic gut bacteria are common causes of intestinal disease. Enteroids-cultured three-dimensional replicas of the mammalian gut-offer an emerging model system to study disease mechanisms under conditions that recapitulate key features of the intestinal tract. In this study, we describe the full life cycle of the prototype gut pathogen Salmonella enterica serovar Typhimurium within human and mouse enteroids. We map the consecutive steps and define the bacterial virulence factors that drive colonization of luminal and epithelial compartments, as well as breaching of the epithelial barrier. Strikingly, our work reveals how bacterial colonization of the epithelium potently fuels expansion also in the luminal compartment, through a mechanism involving the death and expulsion of bacterium-infected epithelial cells. These findings have repercussions for our understanding of the Salmonella infection cycle. Moreover, our work provides a comprehensive foundation for the use of microinjected enteroids to model gut bacterial diseases.
Collapse
|
22
|
Milne-Davies B, Wimmi S, Diepold A. Adaptivity and dynamics in type III secretion systems. Mol Microbiol 2020; 115:395-411. [PMID: 33251695 DOI: 10.1111/mmi.14658] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/17/2020] [Accepted: 11/23/2020] [Indexed: 01/07/2023]
Abstract
The type III secretion system is the common core of two bacterial molecular machines: the flagellum and the injectisome. The flagellum is the most widely distributed prokaryotic locomotion device, whereas the injectisome is a syringe-like apparatus for inter-kingdom protein translocation, which is essential for virulence in important human pathogens. The successful concept of the type III secretion system has been modified for different bacterial needs. It can be adapted to changing conditions, and was found to be a dynamic complex constantly exchanging components. In this review, we highlight the flexibility, adaptivity, and dynamic nature of the type III secretion system.
Collapse
Affiliation(s)
- Bailey Milne-Davies
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Stephan Wimmi
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Andreas Diepold
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| |
Collapse
|
23
|
Wolfson EB, Elvidge J, Tahoun A, Gillespie T, Mantell J, McAteer SP, Rossez Y, Paxton E, Lane F, Shaw DJ, Gill AC, Stevens J, Verkade P, Blocker A, Mahajan A, Gally DL. The interaction of Escherichia coli O157 :H7 and Salmonella Typhimurium flagella with host cell membranes and cytoskeletal components. MICROBIOLOGY (READING, ENGLAND) 2020; 166:947-965. [PMID: 32886602 PMCID: PMC7660914 DOI: 10.1099/mic.0.000959] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/13/2020] [Indexed: 12/11/2022]
Abstract
Bacterial flagella have many established roles beyond swimming motility. Despite clear evidence of flagella-dependent adherence, the specificity of the ligands and mechanisms of binding are still debated. In this study, the molecular basis of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium flagella binding to epithelial cell cultures was investigated. Flagella interactions with host cell surfaces were intimate and crossed cellular boundaries as demarcated by actin and membrane labelling. Scanning electron microscopy revealed flagella disappearing into cellular surfaces and transmission electron microscopy of S. Typhiumurium indicated host membrane deformation and disruption in proximity to flagella. Motor mutants of E. coli O157:H7 and S. Typhimurium caused reduced haemolysis compared to wild-type, indicating that membrane disruption was in part due to flagella rotation. Flagella from E. coli O157 (H7), EPEC O127 (H6) and S. Typhimurium (P1 and P2 flagella) were shown to bind to purified intracellular components of the actin cytoskeleton and directly increase in vitro actin polymerization rates. We propose that flagella interactions with host cell membranes and cytoskeletal components may help prime intimate attachment and invasion for E. coli O157:H7 and S. Typhimurium, respectively.
Collapse
Affiliation(s)
- Eliza B. Wolfson
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
- Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Johanna Elvidge
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Amin Tahoun
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
- Faculty of Veterinary Medicine, Kafrelsheikh University, 33516 Kafr el-Sheikh, Egypt
| | - Trudi Gillespie
- IMPACT Facility, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Judith Mantell
- Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Sean P. McAteer
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Yannick Rossez
- Génie Enzymatique et Cellulaire, UMR 7025 CNRS, Centre de recherche Royallieu, Sorbonne Universités, Université de Technologie de Compiègne, Compiègne Cedex, France
| | - Edith Paxton
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Fiona Lane
- Division of Neurobiology, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Darren J. Shaw
- Division of Clinical Sciences, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Andrew C. Gill
- Division of Neurobiology, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Jo Stevens
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Paul Verkade
- Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Ariel Blocker
- Department of Cellular and Molecular Medicine, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Arvind Mahajan
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - David L. Gally
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| |
Collapse
|
24
|
Zarkani AA, López-Pagán N, Grimm M, Sánchez-Romero MA, Ruiz-Albert J, Beuzón CR, Schikora A. Salmonella Heterogeneously Expresses Flagellin during Colonization of Plants. Microorganisms 2020; 8:microorganisms8060815. [PMID: 32485895 PMCID: PMC7355505 DOI: 10.3390/microorganisms8060815] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 12/19/2022] Open
Abstract
Minimally processed or fresh fruits and vegetables are unfortunately linked to an increasing number of food-borne diseases, such as salmonellosis. One of the relevant virulence factors during the initial phases of the infection process is the bacterial flagellum. Although its function is well studied in animal systems, contradictory results have been published regarding its role during plant colonization. In this study, we tested the hypothesis that Salmonella's flagellin plays a versatile function during the colonization of tomato plants. We have assessed the persistence in plant tissues of a Salmonella enterica wild type strain, and of a strain lacking the two flagellins, FljB and FliC. We detected no differences between these strains concerning their respective abilities to reach distal, non-inoculated parts of the plant. Analysis of flagellin expression inside the plant, at both the population and single cell levels, shows that the majority of bacteria down-regulate flagellin production, however, a small fraction of the population continues to express flagellin at a very high level inside the plant. This heterogeneous expression of flagellin might be an adaptive strategy to the plant environment. In summary, our study provides new insights on Salmonella adaption to the plant environment through the regulation of flagellin expression.
Collapse
Affiliation(s)
- Azhar A. Zarkani
- Julius Kühn-Institut Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (A.A.Z.); (M.G.)
- Department of Biotechnology, College of Science, University of Baghdad, 10071 Baghdad, Iraq
| | - Nieves López-Pagán
- Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Dpto. Biología Celular, Genética y Fisiología, Campus de Teatinos, 29071 Malaga, Spain; (N.L.-P.); (J.R.-A.); (C.R.B.)
| | - Maja Grimm
- Julius Kühn-Institut Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (A.A.Z.); (M.G.)
| | - María Antonia Sánchez-Romero
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Seville, Spain;
- Current address: Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, Calle Profesor García González 2, 41012 Seville, Spain
| | - Javier Ruiz-Albert
- Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Dpto. Biología Celular, Genética y Fisiología, Campus de Teatinos, 29071 Malaga, Spain; (N.L.-P.); (J.R.-A.); (C.R.B.)
| | - Carmen R. Beuzón
- Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Dpto. Biología Celular, Genética y Fisiología, Campus de Teatinos, 29071 Malaga, Spain; (N.L.-P.); (J.R.-A.); (C.R.B.)
| | - Adam Schikora
- Julius Kühn-Institut Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (A.A.Z.); (M.G.)
- Correspondence:
| |
Collapse
|
25
|
Methylation of Salmonella Typhimurium flagella promotes bacterial adhesion and host cell invasion. Nat Commun 2020; 11:2013. [PMID: 32332720 PMCID: PMC7181671 DOI: 10.1038/s41467-020-15738-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 03/13/2020] [Indexed: 11/09/2022] Open
Abstract
The long external filament of bacterial flagella is composed of several thousand copies of a single protein, flagellin. Here, we explore the role played by lysine methylation of flagellin in Salmonella, which requires the methylase FliB. We show that both flagellins of Salmonella enterica serovar Typhimurium, FliC and FljB, are methylated at surface-exposed lysine residues by FliB. A Salmonella Typhimurium mutant deficient in flagellin methylation is outcompeted for gut colonization in a gastroenteritis mouse model, and methylation of flagellin promotes bacterial invasion of epithelial cells in vitro. Lysine methylation increases the surface hydrophobicity of flagellin, and enhances flagella-dependent adhesion of Salmonella to phosphatidylcholine vesicles and epithelial cells. Therefore, posttranslational methylation of flagellin facilitates adhesion of Salmonella Typhimurium to hydrophobic host cell surfaces, and contributes to efficient gut colonization and host infection. Flagellin proteins of Salmonella flagella are methylated. Here, the authors show that flagellin methylation facilitates adhesion of Salmonella to hydrophobic host-cell surfaces, and contributes to efficient gut colonization and host infection.
Collapse
|
26
|
Structural and Functional Comparison of Salmonella Flagellar Filaments Composed of FljB and FliC. Biomolecules 2020; 10:biom10020246. [PMID: 32041169 PMCID: PMC7072241 DOI: 10.3390/biom10020246] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 01/28/2020] [Accepted: 02/04/2020] [Indexed: 11/23/2022] Open
Abstract
The bacterial flagellum is a motility organelle consisting of a long helical filament as a propeller and a rotary motor that drives rapid filament rotation to produce thrust. Salmonellaenterica serovar Typhimurium has two genes of flagellin, fljB and fliC, for flagellar filament formation and autonomously switches their expression at a frequency of 10−3–10−4 per cell per generation. We report here differences in their structures and motility functions under high-viscosity conditions. A Salmonella strain expressing FljB showed a higher motility than one expressing FliC under high viscosity. To examine the reasons for this motility difference, we carried out structural analyses of the FljB filament by electron cryomicroscopy and found that the structure was nearly identical to that of the FliC filament except for the position and orientation of the outermost domain D3 of flagellin. The density of domain D3 was much lower in FljB than FliC, suggesting that domain D3 of FljB is more flexible and mobile than that of FliC. These differences suggest that domain D3 plays an important role not only in changing antigenicity of the filament but also in optimizing motility function of the filament as a propeller under different conditions.
Collapse
|
27
|
Abstract
S. enterica is a major foodborne pathogen, which can be transmitted via several distinct routes from animals and environmental sources to human hosts. Multiple subspecies and serotypes of S. enterica exhibit considerable differences in virulence, host specificity, and colonization. This study provides detailed insights into the dynamics of recombination and its contributions to S. enterica subspecies evolution. Widespread recombination within the species means that new adaptations arising in one lineage can be rapidly transferred to another lineage. We therefore predict that recombination has been an important factor in the emergence of several major disease-causing strains from diverse genomic backgrounds and their ability to adapt to disparate environments. Salmonella is responsible for many nontyphoidal foodborne infections and enteric (typhoid) fever in humans. Of the two Salmonella species, Salmonella enterica is highly diverse and includes 10 known subspecies and approximately 2,600 serotypes. Understanding the evolutionary processes that generate the tremendous diversity in Salmonella is important in reducing and controlling the incidence of disease outbreaks and the emergence of virulent strains. In this study, we aim to elucidate the impact of homologous recombination in the diversification of S. enterica subspecies. Using a data set of previously published 926 Salmonella genomes representing the 10 S. enterica subspecies and Salmonella bongori, we calculated a genus-wide pan-genome composed of 84,041 genes and the S. enterica pan-genome of 81,371 genes. The size of the accessory genomes varies between 12,429 genes in S. enterica subsp. arizonae (subsp. IIIa) to 33,257 genes in S. enterica subsp. enterica (subsp. I). A total of 12,136 genes in the Salmonella pan-genome show evidence of recombination, representing 14.44% of the pan-genome. We identified genomic hot spots of recombination that include genes associated with flagellin and the synthesis of methionine and thiamine pyrophosphate, which are known to influence host adaptation and virulence. Last, we uncovered within-species heterogeneity in rates of recombination and preferential genetic exchange between certain donor and recipient strains. Frequent but biased recombination within a bacterial species may suggest that lineages vary in their response to environmental selection pressure. Certain lineages, such as the more uncommon non-enterica subspecies (non-S. enterica subsp. enterica), may also act as a major reservoir of genetic diversity for the wider population. IMPORTANCES. enterica is a major foodborne pathogen, which can be transmitted via several distinct routes from animals and environmental sources to human hosts. Multiple subspecies and serotypes of S. enterica exhibit considerable differences in virulence, host specificity, and colonization. This study provides detailed insights into the dynamics of recombination and its contributions to S. enterica subspecies evolution. Widespread recombination within the species means that new adaptations arising in one lineage can be rapidly transferred to another lineage. We therefore predict that recombination has been an important factor in the emergence of several major disease-causing strains from diverse genomic backgrounds and their ability to adapt to disparate environments.
Collapse
|
28
|
Felgner S, Spöring I, Pawar V, Kocijancic D, Preusse M, Falk C, Rohde M, Häussler S, Weiss S, Erhardt M. The immunogenic potential of bacterial flagella for Salmonella-mediated tumor therapy. Int J Cancer 2020; 147:448-460. [PMID: 31755108 DOI: 10.1002/ijc.32807] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 11/07/2019] [Accepted: 11/12/2019] [Indexed: 01/07/2023]
Abstract
Genetically engineered Salmonella Typhimurium are potent vectors for prophylactic and therapeutic measures against pathogens as well as cancer. This is based on the potent adjuvanticity that supports strong immune responses. The physiology of Salmonella is well understood. It simplifies engineering of both enhanced immune-stimulatory properties as well as safety features, thus, resulting in an appropriate balance between attenuation and efficacy for clinical applications. A major virulence factor of Salmonella is the flagellum. It is also a strong pathogen-associated molecular pattern recognized by extracellular and intracellular receptors of immune cells of the host. At the same time, it represents a serious metabolic burden. Accordingly, the bacteria evolved tight regulatory mechanisms that control flagella synthesis in vivo. Here, we systematically investigated the immunogenicity and adjuvant properties of various flagella mutants of Salmonella in vitro and in a mouse cancer model in vivo. We found that mutants lacking the flagellum-specific ATPase FliHIJ or the inner membrane ring FliF displayed the greatest stimulatory capacity and strongest antitumor effects, while remaining safe in vivo. Scanning electron microscopy revealed the presence of outer membrane vesicles in the ΔfliF and ΔfliHIJ mutants. Finally, the combination of the ΔfliF and ΔfliHIJ mutations with our previously described attenuated and immunogenic background strain SF102 displayed strong efficacy against the highly resistant cancer cell line RenCa. We thus conclude that manipulating flagella biosynthesis has great potential for the construction of highly efficacious and versatile Salmonella vector strains.
Collapse
Affiliation(s)
- Sebastian Felgner
- Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Imke Spöring
- Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Vinay Pawar
- Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Central Facilities for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Dino Kocijancic
- Institute of Immunology, Medical School Hannover, Hannover, Germany
| | - Matthias Preusse
- Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Christine Falk
- Institute of Transplant Immunology, Medical School Hannover, Hannover, Germany
| | - Manfred Rohde
- Central Facilities for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Susanne Häussler
- Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Siegfried Weiss
- Institute of Immunology, Medical School Hannover, Hannover, Germany
| | - Marc Erhardt
- Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute for Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| |
Collapse
|
29
|
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]
|
30
|
Antibiofilm activity of coenzyme Q0 against Salmonella Typhimurium and its effect on adhesion-invasion and survival-replication. Appl Microbiol Biotechnol 2019; 103:8545-8557. [PMID: 31468089 DOI: 10.1007/s00253-019-10095-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/22/2019] [Accepted: 08/08/2019] [Indexed: 01/08/2023]
Abstract
Salmonella Typhimurium, a common Gram-negative foodborne pathogen, threatens public health and hinders the development of the food industry. In this study, we evaluated the antibiofilm activity of coenzyme Q0 (CoQ0) against S. Typhimurium. Besides, the inhibition of the S. Typhimurium's adhesion to and invasion of Caco-2 cells and its survival and replication in RAW 264.7 cells by CoQ0 were also explored. The minimum inhibitory concentrations and minimal bactericidal concentrations of CoQ0 against Salmonella were both 100-400 μg/mL. Salmonella Typhimurium biofilm formation was effectively inhibited by subinhibitory concentrations (SICs) of CoQ0. The CoQ0-affected biofilm morphology was observed with light microscopy and field-emission scanning electron microscopy. CoQ0 at SICs reduced the swimming motility and quorum sensing of S. Typhimurium and repressed the transcription of critical virulence-related genes. CoQ0 at SICs also clearly reduced the adhesion of S. Typhimurium to and its invasion of Caco-2 cells and reduced its survival and replication within RAW 264.7 macrophage cells. These findings suggest that CoQ0 has strong antibiofilm activity and can be used as an anti-infectious agent against Salmonella.
Collapse
|
31
|
Acharya D, Sullivan MJ, Duell BL, Eveno T, Schembri MA, Ulett GC. Physical Extraction and Fast Protein Liquid Chromatography for Purifying Flagella Filament From Uropathogenic Escherichia coli for Immune Assay. Front Cell Infect Microbiol 2019; 9:118. [PMID: 31069177 PMCID: PMC6491459 DOI: 10.3389/fcimb.2019.00118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 04/03/2019] [Indexed: 01/17/2023] Open
Abstract
Flagella are expressed on the surface of a wide range of bacteria, conferring motility and contributing to virulence and innate immune stimulation. Host-pathogen interaction studies of the roles of flagella in infection, including due to uropathogenic Escherichia coli (UPEC), have used various methods to purify and examine the biology of the major flagella subunit protein, FliC. These studies have offered insight into the ways in which flagella proteins interact with host cells. However, previous methods used to extract and purify FliC, such as mechanical shearing, ultracentrifugation, heterologous expression in laboratory E. coli strains, and precipitation-inducing chemical treatments have various limitations; as a result, there are few observations based on highly purified, non-denatured FliC in the literature. This is especially relevant to host-pathogen interaction studies such as immune assays that are designed to parallel, as closely as possible, naturally-occurring interactions between host cells and flagella. In this study, we sought to establish a new, carefully optimized method to extract and purify non-denatured, native FliC from the reference UPEC strain CFT073 to be suitable for immune assays. To achieve purification of FliC to homogeneity, we used a mutant CFT073 strain containing deletions in four major chaperone-usher fimbriae operons (type 1, F1C and two P fimbrial gene clusters; CFT073Δ4). A sequential flagella extraction method based on mechanical shearing, ultracentrifugation, size exclusion chromatography, protein concentration and endotoxin removal was applied to CFT073Δ4. Protein purity and integrity was assessed using SDS-PAGE, Western blots with anti-flagellin antisera, and native-PAGE. We also generated a fliC-deficient strain, CFT073Δ4ΔfliC, to enable the concurrent preparation of a suitable carrier control to be applied in downstream assays. Innate immune stimulation was examined by exposing J774A.1 macrophages to 0.05-1 μg of purified FliC for 5 h; the supernatants were analyzed for cytokines known to be induced by flagella, including TNF-α, IL-6, and IL-12; the results were assessed in the context of prior literature. Macrophage responses to purified FliC encompassed significant levels of several cytokines consistent with prior literature reports. The purification method described here establishes a new approach to examine highly purified FliC in the context of host-pathogen interaction model systems.
Collapse
Affiliation(s)
- Dhruba Acharya
- School of Medical Science, Griffith University, Southport, QLD, Australia.,Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| | - Matthew J Sullivan
- School of Medical Science, Griffith University, Southport, QLD, Australia.,Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| | - Benjamin L Duell
- School of Medical Science, Griffith University, Southport, QLD, Australia.,Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| | - Tanguy Eveno
- Institute for Glycomics, Griffith University, Southport, QLD, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, QLD, Australia
| | - Glen C Ulett
- School of Medical Science, Griffith University, Southport, QLD, Australia.,Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| |
Collapse
|
32
|
Cadena M, Froenicke L, Britton M, Settles ML, Durbin-Johnson B, Kumimoto E, Gallardo RA, Ferreiro A, Chylkova T, Zhou H, Pitesky M. Transcriptome Analysis of Salmonella Heidelberg after Exposure to Cetylpyridinium Chloride, Acidified Calcium Hypochlorite, and Peroxyacetic Acid. J Food Prot 2019; 82:109-119. [PMID: 30702951 DOI: 10.4315/0362-028x.jfp-18-235] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The application of RNA sequencing in commercial poultry could facilitate a novel approach toward food safety with respect to identifying conditions in food production that mitigate transcription of genes associated with virulence and survivability. In this study, we evaluated the effects of disinfectant exposure on the transcriptomes of two field isolates of Salmonella Heidelberg (SH) isolated from a commercial broiler processing plant in 1992 and 2014. The isolates were each exposed separately to the following disinfectants commonly used in poultry processing: cetylpyridinium chloride (CPC), acidified calcium hypochlorite (aCH), and peroxyacetic acid (PAA). Exposure times were 8 s with CPC to simulate a poultry processing dipping station or 90 min with aCH and PAA to simulate the chiller tank in a poultry processing plant at 4°C. Based on comparison with a publicly available annotated SH reference genome with 5,088 genes, 90 genes were identified as associated with virulence, pathogenicity, and resistance (VPR). Of these 90 VPR genes, 9 (10.0%), 28 (31.1%), and 1 (1.1%) gene were upregulated in SH 2014 and 21 (23.3%), 26 (28.9%), and 2 (2.2%) genes were upregulated in SH 2014 challenged with CPC, aCH, and PAA, respectively. This information and previously reported MICs for the three disinfectants with both SH isolates allow researchers to make more accurate recommendations regarding control methods of SH and public health considerations related to SH in food production facilities where SH has been isolated. For example, the MICs revealed that aCH is ineffective for SH inhibition at regulatory levels allowed for poultry processing and that aCH was ineffective for inhibiting SH growth and caused an upregulation of VPR genes.
Collapse
Affiliation(s)
- Myrna Cadena
- 1 Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA.,2 Cooperative Extension, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Lutz Froenicke
- 3 Genome Center, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Monica Britton
- 3 Genome Center, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Matthew L Settles
- 3 Genome Center, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Blythe Durbin-Johnson
- 4 Department of Public Health Sciences, School of Medicine, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Emily Kumimoto
- 3 Genome Center, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Rodrigo A Gallardo
- 1 Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Aura Ferreiro
- 1 Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA.,2 Cooperative Extension, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Tereza Chylkova
- 1 Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA.,2 Cooperative Extension, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Huaijun Zhou
- 5 Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, One Shields Avenue, Davis, California 95616, USA
| | - Maurice Pitesky
- 1 Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA.,2 Cooperative Extension, University of California, One Shields Avenue, Davis, California 95616, USA
| |
Collapse
|
33
|
Westerman TL, Bogomolnaya L, Andrews-Polymenis HL, Sheats MK, Elfenbein JR. The Salmonella type-3 secretion system-1 and flagellar motility influence the neutrophil respiratory burst. PLoS One 2018; 13:e0203698. [PMID: 30204776 PMCID: PMC6133356 DOI: 10.1371/journal.pone.0203698] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 08/24/2018] [Indexed: 11/28/2022] Open
Abstract
Neutrophils are innate immune response cells designed to kill invading microorganisms. One of the mechanisms neutrophils use to kill bacteria is generation of damaging reactive oxygen species (ROS) via the respiratory burst. However, during enteric salmonellosis, neutrophil-derived ROS actually facilitates Salmonella expansion and survival in the gut. This seeming paradox led us to hypothesize that Salmonella may possess mechanisms to influence the neutrophil respiratory burst. In this work, we used an in vitro Salmonella-neutrophil co-culture model to examine the impact of enteric infection relevant virulence factors on the respiratory burst of human neutrophils. We report that neutrophils primed with granulocyte-macrophage colony stimulating factor and suspended in serum containing complement produce a robust respiratory burst when stimulated with viable STm. The magnitude of the respiratory burst increases when STm are grown under conditions to induce the expression of the type-3 secretion system-1. STm mutants lacking the type-3 secretion system-1 induce less neutrophil ROS than the virulent WT. In addition, we demonstrate that flagellar motility is a significant agonist of the neutrophil respiratory burst. Together our data demonstrate that both the type-3 secretion system-1 and flagellar motility, which are established virulence factors in enteric salmonellosis, also appear to directly influence the magnitude of the neutrophil respiratory burst in response to STm in vitro.
Collapse
Affiliation(s)
- Trina L. Westerman
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States of America
| | - Lydia Bogomolnaya
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States of America
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | - Helene L. Andrews-Polymenis
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States of America
| | - M. Katherine Sheats
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States of America
| | - Johanna R. Elfenbein
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States of America
| |
Collapse
|
34
|
Dufresne K, Saulnier-Bellemare J, Daigle F. Functional Analysis of the Chaperone-Usher Fimbrial Gene Clusters of Salmonella enterica serovar Typhi. Front Cell Infect Microbiol 2018; 8:26. [PMID: 29473020 PMCID: PMC5809473 DOI: 10.3389/fcimb.2018.00026] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/19/2018] [Indexed: 01/11/2023] Open
Abstract
The human-specific pathogen Salmonella enterica serovar Typhi causes typhoid, a major public health issue in developing countries. Several aspects of its pathogenesis are still poorly understood. S. Typhi possesses 14 fimbrial gene clusters including 12 chaperone-usher fimbriae (stg, sth, bcf, fim, saf, sef, sta, stb, stc, std, ste, and tcf). These fimbriae are weakly expressed in laboratory conditions and only a few are actually characterized. In this study, expression of all S. Typhi chaperone-usher fimbriae and their potential roles in pathogenesis such as interaction with host cells, motility, or biofilm formation were assessed. All S. Typhi fimbriae were better expressed in minimal broth. Each system was overexpressed and only the fimbrial gene clusters without pseudogenes demonstrated a putative major subunits of about 17 kDa on SDS-PAGE. Six of these (Fim, Saf, Sta, Stb, Std, and Tcf) also show extracellular structure by electron microscopy. The impact of fimbrial deletion in a wild-type strain or addition of each individual fimbrial system to an S. Typhi afimbrial strain were tested for interactions with host cells, biofilm formation and motility. Several fimbriae modified bacterial interactions with human cells (THP-1 and INT-407) and biofilm formation. However, only Fim fimbriae had a deleterious effect on motility when overexpressed. Overall, chaperone-usher fimbriae seem to be an important part of the balance between the different steps (motility, adhesion, host invasion and persistence) of S. Typhi pathogenesis.
Collapse
Affiliation(s)
- Karine Dufresne
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC, Canada
| | - Julie Saulnier-Bellemare
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC, Canada
| | - France Daigle
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC, Canada
| |
Collapse
|
35
|
Shippy DC, Bearson BL, Holman DB, Brunelle BW, Allen HK, Bearson SMD. Porcine Response to a Multidrug-Resistant Salmonella enterica serovar I 4,[5],12:i:- Outbreak Isolate. Foodborne Pathog Dis 2018; 15:253-261. [PMID: 29412766 DOI: 10.1089/fpd.2017.2378] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Salmonella enterica serovar I 4,[5],12:i:- has emerged as a common nontyphoidal Salmonella serovar to cause human foodborne illness. An interesting trait of serovar I 4,[5],12:i:- is that it only expresses the fliC gene for bacterial motility (i.e., monophasic), while most Salmonella strains alternately express two flagellin genes (fliC and fljB). The goal of this study was to characterize the porcine response following inoculation with a multidrug-resistant (MDR) serovar I 4,[5],12:i:- isolate associated with a multistate pork outbreak to determine if the increased prevalence of serovar I 4,[5],12:i:- in swine is due to enhanced pathogenicity. Pigs were inoculated and subsequently evaluated for the ability of the isolate to colonize intestinal tissues, cause clinical symptoms, induce an immune response, and alter the fecal microbiota over a 7-day period. Pigs exhibited a significant increase in rectal temperature (fever) (p < 0.01) and fecal moisture content (diarrhea) (p < 0.05) at 2 days postinoculation (d.p.i.) compared with preinoculation (day 0). Serum analyses revealed significantly increased interferon-gamma (IFN-γ) levels at 2 (p ≤ 0.0001) and 3 (p < 0.01) d.p.i. compared with day 0, and antibodies against Salmonella lipopolysaccharide (LPS) were present in all pigs by 7 d.p.i. Serovar I 4,[5],12:i:- colonized porcine intestinal tissues and was shed in the feces throughout the 7-day study. Analysis of the 16S rRNA gene sequences demonstrated that the fecal microbiota was significantly altered following MDR serovar I 4,[5],12:i:- inoculation, with the largest shift observed between 0 and 7 d.p.i. Our data indicate that the pork outbreak-associated MDR serovar I 4,[5],12:i:- isolate induced transient clinical disease in swine and perturbed the gastrointestinal microbial community. The porcine response to MDR serovar I 4,[5],12:i:- is similar to previous studies with virulent biphasic Salmonella enterica serovar Typhimurium, suggesting that the absence of fljB does not substantially alter acute colonization or pathogenesis in pigs.
Collapse
Affiliation(s)
- Daniel C Shippy
- 1 Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center , Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa
| | - Bradley L Bearson
- 2 Agroecosystems Management Research Unit, National Laboratory for Agriculture and the Environment, Agricultural Research Service, U.S. Department of Agriculture , Ames, Iowa
| | - Devin B Holman
- 1 Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center , Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa
| | - Brian W Brunelle
- 1 Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center , Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa
| | - Heather K Allen
- 1 Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center , Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa
| | - Shawn M D Bearson
- 1 Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center , Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa
| |
Collapse
|
36
|
García-Pastor L, Puerta-Fernández E, Casadesús J. Bistability and phase variation in Salmonella enterica. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:752-758. [PMID: 29369799 DOI: 10.1016/j.bbagrm.2018.01.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 01/09/2018] [Indexed: 11/18/2022]
Abstract
Cell-to-cell differences in bacterial gene expression can merely reflect the occurrence of noise. In certain cases, however, heterogeneous gene expression is a programmed event that results in bistable expression. If bistability is heritable, bacterial lineages are formed. When programmed bistability is reversible, the phenomenon is known as phase variation. In certain cases, bistability is controlled by genetic mechanisms (e. g., DNA rearrangement). In other cases, bistability has epigenetic origin. A robust epigenetic mechanism for the formation of bacterial lineages is the formation of heritable DNA methylation patterns. However, bistability can also arise upon propagation of gene expression patterns by feedback loops that are stable upon cell division. This review describes examples of bistability and phase variation in Salmonella enterica and discusses their adaptive value, sometimes in a speculative manner.
Collapse
Affiliation(s)
- Lucía García-Pastor
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain
| | - Elena Puerta-Fernández
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain
| | - Josep Casadesús
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
| |
Collapse
|
37
|
Bacterial Flagellins: Does Size Matter? Trends Microbiol 2017; 26:575-581. [PMID: 29258714 DOI: 10.1016/j.tim.2017.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/20/2017] [Accepted: 11/29/2017] [Indexed: 01/31/2023]
Abstract
The bacterial flagellum is the principal organelle of motility in bacteria. Here, we address the question of size when applied to the chief flagellar protein flagellin and the flagellar filament. Surprisingly, nature furnishes multiple examples of 'giant flagellins' greater than a thousand amino acids in length, with large surface-exposed hypervariable domains. We review the contexts in which these giant flagellins occur, speculate as to their functions, and highlight the potential for biotechnology to build on what nature provides.
Collapse
|
38
|
Miranda-CasoLuengo AA, Kary SC, Erhardt M, Kröger C. Small RNA, Big Effect: Control of Flagellin Production. Trends Microbiol 2017; 25:953-954. [PMID: 29097088 DOI: 10.1016/j.tim.2017.10.003] [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: 10/17/2017] [Accepted: 10/18/2017] [Indexed: 10/18/2022]
Abstract
Many bacteria move in their environment using a remarkable, rotating nanomachine - the flagellum. In a recent publication, Choi et al. report a new addition to the group of flagellar regulators, a trans-acting small RNA (sRNA).
Collapse
Affiliation(s)
- Aleksandra A Miranda-CasoLuengo
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Stefani C Kary
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Marc Erhardt
- Humboldt-Universität zu Berlin, Institute for Biology - Bacterial physiology, Berlin, Germany
| | - Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland.
| |
Collapse
|
39
|
Abstract
Bacteria use flagella to move toward nutrients, find its host, or retract from toxic substances. Because bacterial flagellum is one of the ligands that activate the host innate immune system, its synthesis should be tightly regulated during host infection, which is largely unknown. Here, we report that a bacterial leader mRNA from the mgtCBR virulence operon in the intracellular pathogen Salmonella enterica serovar Typhimurium binds to the fljB coding region of mRNAs in the fljBA operon encoding the FljB phase 2 flagellin, a main component of bacterial flagella and the FljA repressor for the FliC phase 1 flagellin, and degrades fljBA mRNAs in an RNase E-dependent fashion during infection. A nucleotide substitution of the fljB flagellin gene that prevents the mgtC leader RNA-mediated down-regulation increases the fljB-encoded flagellin synthesis, leading to a hypermotile phenotype inside macrophages. Moreover, the fljB nucleotide substitution renders Salmonella hypervirulent, indicating that FljB-based motility must be compromised in the phagosomal compartment where Salmonella resides. This suggests that this pathogen promotes pathogenicity by producing a virulence protein and limits locomotion by a trans-acting leader RNA from the same virulence gene during infection.
Collapse
|