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Ye D, Nguyen PT, Bourgault S, Couture M. The heme binding protein ChuX is a regulator of heme degradation by the ChuS protein in Escherichia coli O157:H7. J Inorg Biochem 2024; 256:112575. [PMID: 38678912 DOI: 10.1016/j.jinorgbio.2024.112575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/01/2024]
Abstract
Escherichia coli O157:H7 possesses an 8-gene cluster (chu genes) that contains genes involved in heme transport and processing from the human host. Among the chu genes, four encode cytoplasmic proteins (ChuS, ChuX, ChuY and ChuW). ChuX was previously shown to be a heme binding protein and to assist ChuW in heme degradation under anaerobic conditions. The purpose of this work was to investigate if ChuX works in concert with ChuS, which is a protein able to degrade heme by a non-canonical mechanism and release the iron from the porphyrin under aerobic conditions using hydrogen peroxide as the oxidant. We showed that when the heme-bound ChuX and apo-ChuS protein are mixed, heme is efficiently transferred from ChuX to ChuS. Heme-bound ChuX displayed a peroxidase activity with ABTS and H2O2 but not heme-bound ChuS, which is an efficient test to determine the protein to which heme is bound in the ChuS-ChuX complex. We found that ChuX protects heme from chemical oxidation and that it has no heme degradation activity by itself. Unexpectedly, we found that ChuX inhibits heme degradation by ChuS and stops the reaction at an early intermediate. We determined using surface plasmon resonance that ChuX interacts with ChuS and that it forms a relatively stable complex. These results indicate that ChuX in addition to its heme transfer activity is a regulator of ChuS activity, a function that was not described before for any of the heme carrier protein that delivers heme to heme degradation enzymes.
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Affiliation(s)
- Danrong Ye
- Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec City, QC, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS) and PROTEO, Université Laval, Quebec city, QC, Canada; Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada
| | - Phuong Trang Nguyen
- Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada; Departement of Chemistry, Université du Québec à Montréal, Montreal, QC, Canada
| | - Steve Bourgault
- Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada; Departement of Chemistry, Université du Québec à Montréal, Montreal, QC, Canada
| | - Manon Couture
- Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec City, QC, Canada; Institut de Biologie Intégrative et des Systèmes (IBIS) and PROTEO, Université Laval, Quebec city, QC, Canada; Quebec Network for Research on Protein Function, Engineering and Applications (PROTEO), Montreal, QC, Canada.
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2
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Cottam C, White RT, Beck LC, Stewart CJ, Beatson SA, Lowe EC, Grinter R, Connolly JPR. Metabolism of L-arabinose converges with virulence regulation to promote enteric pathogen fitness. Nat Commun 2024; 15:4462. [PMID: 38796512 PMCID: PMC11127945 DOI: 10.1038/s41467-024-48933-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 05/16/2024] [Indexed: 05/28/2024] Open
Abstract
Virulence and metabolism are often interlinked to control the expression of essential colonisation factors in response to host-associated signals. Here, we identified an uncharacterised transporter of the dietary monosaccharide ʟ-arabinose that is widely encoded by the zoonotic pathogen enterohaemorrhagic Escherichia coli (EHEC), required for full competitive fitness in the mouse gut and highly expressed during human infection. Discovery of this transporter suggested that EHEC strains have an enhanced ability to scavenge ʟ-arabinose and therefore prompted us to investigate the impact of this nutrient on pathogenesis. Accordingly, we discovered that ʟ-arabinose enhances expression of the EHEC type 3 secretion system, increasing its ability to colonise host cells, and that the underlying mechanism is dependent on products of its catabolism rather than the sensing of ʟ-arabinose as a signal. Furthermore, using the murine pathogen Citrobacter rodentium, we show that ʟ-arabinose metabolism provides a fitness benefit during infection via virulence factor regulation, as opposed to supporting pathogen growth. Finally, we show that this mechanism is not restricted to ʟ-arabinose and extends to other pentose sugars with a similar metabolic fate. This work highlights the importance integrating central metabolism with virulence regulation in order to maximise competitive fitness of enteric pathogens within the host-niche.
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Affiliation(s)
- Curtis Cottam
- Newcastle University Biosciences Institute, Newcastle University, NE2 4HH, Newcastle-upon-Tyne, UK
| | - Rhys T White
- Institute of Environmental Science and Research, Wellington, New Zealand
- Australian Infectious Diseases Research Centre and School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Lauren C Beck
- Newcastle University Translation and Clinical Research Institute, Newcastle University, NE2 4HH, Newcastle-upon-Tyne, UK
| | - Christopher J Stewart
- Newcastle University Translation and Clinical Research Institute, Newcastle University, NE2 4HH, Newcastle-upon-Tyne, UK
| | - Scott A Beatson
- Australian Infectious Diseases Research Centre and School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Elisabeth C Lowe
- Newcastle University Biosciences Institute, Newcastle University, NE2 4HH, Newcastle-upon-Tyne, UK
| | - Rhys Grinter
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - James P R Connolly
- Newcastle University Biosciences Institute, Newcastle University, NE2 4HH, Newcastle-upon-Tyne, UK.
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3
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Neetu N, Mahto JK, Sharma M, Katiki M, Dhaka P, Roy P, Tomar S, Narayan A, Yernool D, Kumar P. Sulisobenzone is a potent inhibitor of the global transcription factor Cra. J Struct Biol 2023; 215:108034. [PMID: 37805153 DOI: 10.1016/j.jsb.2023.108034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 09/27/2023] [Accepted: 10/04/2023] [Indexed: 10/09/2023]
Abstract
Transcription is carried out by the RNA polymerase and is regulated through a series of interactions with transcription factors. Catabolite activator repressor (Cra), a LacI family transcription factor regulates the virulence gene expression in Enterohaemorrhagic Escherichia coli (EHEC) and thus is a promising drug target for the discovery of antivirulence molecules. Here, we report the crystal structure of the effector molecule binding domain of Cra from E. coli (EcCra) in complex with HEPES molecule. Based on the EcCra-HEPES complex structure, ligand screening was performed that identified sulisobenzone as an potential inhibitor of EcCra. The electrophoretic mobility shift assay (EMSA) and in vitro transcription assay validated the sulisobenzone binding to EcCra. Moreover, the isothermal titration calorimetry (ITC) experiments demonstrated a 40-fold higher binding affinity of sulisobenzone (KD 360 nM) compared to the HEPES molecule. Finally, the sulisobenzone bound EcCra complex crystal structure was determined to elucidate the binding mechanism of sulisobenzone to the effector binding pocket of EcCra. Together, this study suggests that sulisobenzone may be a promising candidate that can be studied and developed as an effective antivirulence agent against EHEC.
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Affiliation(s)
- Neetu Neetu
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Jai Krishna Mahto
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Monica Sharma
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Madhusudhanarao Katiki
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Preeti Dhaka
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Partha Roy
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Shailly Tomar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Anoop Narayan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Dinesh Yernool
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47906, USA
| | - Pravindra Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India.
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4
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Sui X, Yang X, Luo M, Wang H, Liu Q, Sun H, Jin Y, Wu Y, Bai X, Xiong Y. Characteristics of Shiga Toxin-Producing Escherichia coli Circulating in Asymptomatic Food Handlers. Toxins (Basel) 2023; 15:640. [PMID: 37999503 PMCID: PMC10675304 DOI: 10.3390/toxins15110640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/22/2023] [Accepted: 10/31/2023] [Indexed: 11/25/2023] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a foodborne zoonotic pathogen that causes diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS) worldwide. Since the infection can be asymptomatic, the circulation of STEC in some asymptomatic carriers, especially in healthy-food-related professionals, is not yet well understood. In this study, a total of 3987 anal swab samples from asymptomatic food handlers were collected, and ten swabs recovered STEC strains (0.251%). Of the ten STEC isolates, seven serotypes and eight sequence types (ST) were determined using whole genome sequencing (WGS). Two stx1 subtypes (stx1a and stx1c) and four stx2 subtypes (stx2a, stx2b, stx2d, and stx2e) were detected. Seven different insertion sites were found in fourteen Stx prophages, and the dmsB and yfhL were the newly identified insertion sites. The ten strains showed the variable Stx transcription levels after the mitomycin C induction. The whole-genome phylogeny indicated that the strains from the asymptomatic food handlers were genetically distant from the strains of HUS patients. The STEC isolates circulating in asymptomatic carriers might pose a low potential to cause disease.
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Affiliation(s)
- Xinxia Sui
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Xi Yang
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Ming Luo
- Yulin Center for Disease Control and Prevention, Yulin 537000, China
| | - Hua Wang
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Qian Liu
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Hui Sun
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Yujuan Jin
- Longgang Center for Disease Control and Prevention, Shenzhen 518172, China
| | - Yannong Wu
- Yulin Center for Disease Control and Prevention, Yulin 537000, China
| | - Xiangning Bai
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
- Division of Laboratory Medicine, Oslo University Hospital, 0372 Oslo, Norway
| | - Yanwen Xiong
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
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Abstract
Bacteria thrive in environments rich in fluid flow, such as the gastrointestinal tract, bloodstream, aquatic systems, and the urinary tract. Despite the importance of flow, how flow affects bacterial life is underappreciated. In recent years, the combination of approaches from biology, physics, and engineering has led to a deeper understanding of how bacteria interact with flow. Here, we highlight the wide range of bacterial responses to flow, including changes in surface adhesion, motility, surface colonization, quorum sensing, virulence factor production, and gene expression. To emphasize the diversity of flow responses, we focus our review on how flow affects four ecologically distinct bacterial species: Escherichia coli, Staphylococcus aureus, Caulobacter crescentus, and Pseudomonas aeruginosa. Additionally, we present experimental approaches to precisely study bacteria in flow, discuss how only some flow responses are triggered by shear force, and provide perspective on flow-sensitive bacterial signaling.
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Affiliation(s)
- Gilberto C. Padron
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Alexander M. Shuppara
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Jessica-Jae S. Palalay
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Anuradha Sharma
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Joseph E. Sanfilippo
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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6
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Genomic Island-Encoded Histidine Kinase and Response Regulator Coordinate Mannose Utilization with Virulence in Enterohemorrhagic Escherichia coli. mBio 2023; 14:e0315222. [PMID: 36786613 PMCID: PMC10128022 DOI: 10.1128/mbio.03152-22] [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: 02/15/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a highly adaptive pathogen and has acquired diverse genetic elements, such as genomic islands and prophages, via horizontal gene transfer to promote fitness in vivo. Two-component signaling systems (TCSs) allow bacteria to sense, respond to, and adapt to various environments. This study identified a putative two-component signaling system composed of the histidine kinase EDL5436 (renamed LmvK) and the response regulator EDL5428 (renamed LmvR) in EHEC. lmvK and lmvR along with EDL5429 to EDL5434 (EDL5429-5434) between them constitute the OI167 genomic island and are highly associated with the EHEC pathotype. EDL5429-5434 encode transporters and metabolic enzymes that contribute to growth on mannose and are directly upregulated by LmvK/LmvR in the presence of mannose, as revealed by quantitative PCR (qPCR) and DNase I footprint assays. Moreover, LmvR directly activates the expression of the type III secretion system in response to mannose and promotes the formation of attaching and effacing lesions on HeLa cells. Using human colonoid and mouse infection models, we show that lmvK and lmvR contributed greatly to adherence and microcolony (MC) formation ex vivo and colonization in vivo. Finally, RNA sequencing and chromatin immunoprecipitation coupled with sequencing analyses identified additional direct targets of LmvR, most of which are involved in metabolism. Given that mannose is a mucus-derived sugar that induces virulence and is preferentially used by EHEC during infection, our data revealed a previously unknown mechanism by which EHEC recognizes the host metabolic landscape and regulates virulence expression accordingly. Our findings provide insights into how pathogenic bacteria evolve by acquiring genetic elements horizontally to adapt to host environments. IMPORTANCE The gastrointestinal tract represents a complex and challenging environment for enterohemorrhagic Escherichia coli (EHEC). However, EHEC is a highly adaptable pathogen, requiring only 10 to 100 CFUs to cause infection. This ability was achieved partially by acquiring mobile genetic elements, such as genomic islands, that promote overall fitness. Mannose is an intestinal mucus-derived sugar that stimulates virulence and is preferentially used by EHEC during infection. Here, we characterize the OI167 genomic island of EHEC, which encodes a novel two-component signaling system (TCS) and transporters and metabolic enzymes (EDL5429-5434) involved in mannose utilization. The TCS directly upregulates EDL5429-5434 and genes encoding the type III secretion system in the presence of mannose. Moreover, the TCS contributes greatly to EHEC virulence ex vivo and in vivo. Our data demonstrate an elegant example in which EHEC strains evolve by acquiring genetic elements horizontally to recognize the host metabolic landscape and regulate virulence expression accordingly, leading to successful infections.
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7
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Garimano N, Scalise ML, Gómez F, Amaral MM, Ibarra C. Intestinal mucus-derived metabolites modulate virulence of a clade 8 enterohemorrhagic Escherichia coli O157:H7. Front Cell Infect Microbiol 2022; 12:975173. [PMID: 36004327 PMCID: PMC9393340 DOI: 10.3389/fcimb.2022.975173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/20/2022] [Indexed: 11/24/2022] Open
Abstract
The human colonic mucus is mainly composed of mucins, which are highly glycosylated proteins. The normal commensal colonic microbiota has mucolytic activity and is capable of releasing the monosaccharides contained in mucins, which can then be used as carbon sources by pathogens such as Enterohemorrhagic Escherichia coli (EHEC). EHEC can regulate the expression of some of its virulence factors through environmental sensing of mucus-derived sugars, but its implications regarding its main virulence factor, Shiga toxin type 2 (Stx2), among others, remain unknown. In the present work, we have studied the effects of five of the most abundant mucolytic activity-derived sugars, Fucose (L-Fucose), Galactose (D-Galactose), N-Gal (N-acetyl-galactosamine), NANA (N-Acetyl-Neuraminic Acid) and NAG (N-Acetyl-D-Glucosamine) on EHEC growth, adhesion to epithelial colonic cells (HCT-8), and Stx2 production and translocation across a polarized HCT-8 monolayer. We found that bacterial growth was maximum when using NAG and NANA compared to Galactose, Fucose or N-Gal, and that EHEC adhesion was inhibited regardless of the metabolite used. On the other hand, Stx2 production was enhanced when using NAG and inhibited with the rest of the metabolites, whilst Stx2 translocation was only enhanced when using NANA, and this increase occurred only through the transcellular route. Overall, this study provides insights on the influence of the commensal microbiota on the pathogenicity of E. coli O157:H7, helping to identify favorable intestinal environments for the development of severe disease.
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Sy BM, Tree JJ. The Small RNA CyaR Activates Translation of the Outer Membrane Haem Receptor chuA in Enterohemorrhagic Escherichia coli. Front Microbiol 2022; 13:821196. [PMID: 35422774 PMCID: PMC9002310 DOI: 10.3389/fmicb.2022.821196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/10/2022] [Indexed: 12/22/2022] Open
Abstract
To sense the transition from environment to host, bacteria use a range of environmental cues to control expression of virulence genes. Iron is tightly sequestered in host tissues and in the human pathogen enterohemorrhagic Escherichia coli (EHEC) iron-limitation induces transcription of the outer membrane haem transporter encoded by chuAS. ChuA expression is post-transcriptionally activated at 37°C by a FourU RNA thermometer ensuring that the haem receptor is only expressed under low iron, high temperature conditions that indicate the host. Here we demonstrate that expression of chuA is also independently regulated by the cAMP-responsive small RNA (sRNA) CyaR and transcriptional terminator Rho. These results indicate that chuAS expression is regulated at the transcription initiation, transcript elongation, and translational level. We speculate that additional sensing of the gluconeogenic environment allows further precision in determining when EHEC is at the gastrointestinal epithelium of the host. With previous studies, it appears that the chuAS transcript is controlled by eight regulatory inputs that control expression through six different transcriptional and post-transcriptional mechanisms. The results highlight the ability of regulatory sRNAs to integrate multiple environmental signals into a layered hierarchy of signal input.
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Affiliation(s)
- Brandon M Sy
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Jai J Tree
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
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9
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Strain R, Stanton C, Ross RP. Effect of diet on pathogen performance in the microbiome. MICROBIOME RESEARCH REPORTS 2022; 1:13. [PMID: 38045644 PMCID: PMC10688830 DOI: 10.20517/mrr.2021.10] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/17/2022] [Accepted: 02/23/2022] [Indexed: 12/05/2023]
Abstract
Intricate interactions among commensal bacteria, dietary substrates and immune responses are central to defining microbiome community composition, which plays a key role in preventing enteric pathogen infection, a dynamic phenomenon referred to as colonisation resistance. However, the impact of diet on sculpting microbiota membership, and ultimately colonisation resistance has been overlooked. Furthermore, pathogens have evolved strategies to evade colonisation resistance and outcompete commensal microbiota by using unique nutrient utilisation pathways, by exploiting microbial metabolites as nutrient sources or by environmental cues to induce virulence gene expression. In this review, we will discuss the interplay between diet, microbiota and their associated metabolites, and how these can contribute to or preclude pathogen survival.
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Affiliation(s)
- Ronan Strain
- APC Microbiome Ireland, Biosciences Institute, University College Cork, Cork T12 YT20, Ireland
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork P61 C996, Ireland
| | - Catherine Stanton
- APC Microbiome Ireland, Biosciences Institute, University College Cork, Cork T12 YT20, Ireland
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork P61 C996, Ireland
| | - R. Paul Ross
- APC Microbiome Ireland, Biosciences Institute, University College Cork, Cork T12 YT20, Ireland
- School of Microbiology, University College Cork, College Road, Cork T12 K8AF, Ireland
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10
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Shimizu T, Onuki M, Suzuki S, Hirai S, Yokoyama E, Matsumoto A, Hamabata T. Enhanced production of Shiga toxin 1 in enterohaemorrhagic Escherichia coli by oxygen. MICROBIOLOGY (READING, ENGLAND) 2021; 167. [PMID: 34951398 DOI: 10.1099/mic.0.001122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) produces Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2). Although stx1 and stx2 were found within the late operons of the Stx-encoding phages (Stx-phages), stx1 could mainly be transcribed from the stx1 promoter (P Stx1), which represents the functional operator-binding site (Fur box) for the transcriptional regulator Fur (ferric uptake regulator), upstream of stx1. In this study, we found that the production of Stx1 by EHEC was affected by oxygen concentration. Increased Stx1 production in the presence of oxygen is dependent on Fur, which is an Fe2+-responsive transcription factor. The intracellular Fe2+ pool was lower under microaerobic conditions than under anaerobic conditions, suggesting that lower Fe2+ availability drove the formation of less Fe2+-Fur, less DNA binding to the P Stx1 region, and an increase in Stx1 production.
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Affiliation(s)
- Takeshi Shimizu
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan
| | - Manami Onuki
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan
| | - Shin Suzuki
- Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan
| | - Shinichiro Hirai
- Department of Infectious Disease Risk Management Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Eiji Yokoyama
- Division of Bacteriology, Chiba Prefectural Institute of Public Health, 666-2 Nitona, Chuo-ku, Chiba, 260-8715, Japan
| | - Akio Matsumoto
- Department of Aging Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-Nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Takashi Hamabata
- Department of Infectious Disease, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
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11
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Sauder AB, Kendall MM. A pathogen-specific sRNA influences enterohemorrhagic Escherichia coli fitness and virulence in part by direct interaction with the transcript encoding the ethanolamine utilization regulatory factor EutR. Nucleic Acids Res 2021; 49:10988-11004. [PMID: 34591974 PMCID: PMC8565329 DOI: 10.1093/nar/gkab863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 01/07/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 relies on sRNAs to coordinate expression of metabolic and virulence factors to colonize the host. Here, we focus on the sRNA, named MavR (metabolism and virulence regulator), that is conserved among pathogenic Enterobacteriaceae. MavR is constitutively expressed under in vitro conditions that promote EHEC virulence gene expression. Using MS2-affinity purification coupled with RNA sequencing, the eutR transcript was identified as a putative target of MavR. EutR is a transcription factor that promotes expression of genes required for ethanolamine metabolism as well as virulence factors important for host colonization. MavR binds to the eutR coding sequence to protect the eutR transcript from RNase E-mediated degradation. Ultimately, MavR promotes EutR expression and in turn ethanolamine utilization and ethanolamine-dependent growth. RNAseq analyses revealed that MavR also affected expression of genes important for other metabolic pathways, motility, oxidative stress and attaching and effacing lesion formation, which contribute to EHEC colonization of the gastrointestinal tract. In support of the idea that MavR-dependent gene expression affects fitness during infection, deletion of mavR resulted in significant (∼10- to 100-fold) attenuation in colonization of the mammalian intestine. Altogether, these studies reveal an important, extensive, and robust phenotype for a bacterial sRNA in host-pathogen interactions.
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Affiliation(s)
- Amber B Sauder
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Melissa M Kendall
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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12
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Mucolytic bacteria: prevalence in various pathological diseases. World J Microbiol Biotechnol 2021; 37:176. [PMID: 34519941 DOI: 10.1007/s11274-021-03145-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/07/2021] [Indexed: 02/07/2023]
Abstract
All mucins are highly glycosylated and a key constituent of the mucus layer that is vigilant against pathogens in many organ systems of animals and humans. The viscous layer is organized in bilayers, i.e., an outer layer that is loosely arranged, variable in thickness, home to the commensal microbiota that grows in the complex environment, and an innermost layer that is stratified, non-aspirated, firmly adherent to the epithelial cells and devoid of any microorganisms. The O-glycosylation moiety represents the site of adhesion for pathogens and due to the increase of motility, mucolytic activity, and upregulation of virulence factors, some microorganisms can circumvent the component of the mucus layer and cause disruption in organ homeostasis. A dysbiotic microbiome, defective mucus barrier, and altered immune response often result in various diseases. In this review, paramount emphasis is given to the role played by the bacterial species directly or indirectly involved in mucin degradation, alteration in mucus secretion or its composition or mucin gene expression, which instigates many diseases in the digestive, respiratory, and other organ systems. A systematic view can help better understand the etiology of some complex disorders such as cystic fibrosis, ulcerative colitis and expand our knowledge about mucin degraders to develop new therapeutic approaches to correct ill effects caused by these mucin-dwelling pathogens.
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13
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Sauvaitre T, Etienne-Mesmin L, Sivignon A, Mosoni P, Courtin CM, Van de Wiele T, Blanquet-Diot S. Tripartite relationship between gut microbiota, intestinal mucus and dietary fibers: towards preventive strategies against enteric infections. FEMS Microbiol Rev 2021; 45:5918835. [PMID: 33026073 DOI: 10.1093/femsre/fuaa052] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/05/2020] [Indexed: 02/06/2023] Open
Abstract
The human gut is inhabited by a large variety of microorganims involved in many physiological processes and collectively referred as to gut microbiota. Disrupted microbiome has been associated with negative health outcomes and especially could promote the onset of enteric infections. To sustain their growth and persistence within the human digestive tract, gut microbes and enteric pathogens rely on two main polysaccharide compartments, namely dietary fibers and mucus carbohydrates. Several evidences suggest that the three-way relationship between gut microbiota, dietary fibers and mucus layer could unravel the capacity of enteric pathogens to colonise the human digestive tract and ultimately lead to infection. The review starts by shedding light on similarities and differences between dietary fibers and mucus carbohydrates structures and functions. Next, we provide an overview of the interactions of these two components with the third partner, namely, the gut microbiota, under health and disease situations. The review will then provide insights into the relevance of using dietary fibers interventions to prevent enteric infections with a focus on gut microbial imbalance and impaired-mucus integrity. Facing the numerous challenges in studying microbiota-pathogen-dietary fiber-mucus interactions, we lastly describe the characteristics and potentialities of currently available in vitro models of the human gut.
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Affiliation(s)
- Thomas Sauvaitre
- Université Clermont Auvergne, UMR 454 INRAe, Microbiology, Digestive Environment and Health (MEDIS), Clermont-Ferrand, France.,Ghent University, Faculty of Bioscience Engineering, Center for Microbial Ecology and Technology (CMET), Ghent, Belgium
| | - Lucie Etienne-Mesmin
- Université Clermont Auvergne, UMR 454 INRAe, Microbiology, Digestive Environment and Health (MEDIS), Clermont-Ferrand, France
| | - Adeline Sivignon
- Université Clermont Auvergne, UMR 1071 Inserm, USC-INRAe 2018, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte (M2iSH), Clermont-Ferrand, France
| | - Pascale Mosoni
- Université Clermont Auvergne, UMR 454 INRAe, Microbiology, Digestive Environment and Health (MEDIS), Clermont-Ferrand, France
| | - Christophe M Courtin
- KU Leuven, Faculty of Bioscience Engineering, Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe), Leuven, Belgium
| | - Tom Van de Wiele
- Ghent University, Faculty of Bioscience Engineering, Center for Microbial Ecology and Technology (CMET), Ghent, Belgium
| | - Stéphanie Blanquet-Diot
- Université Clermont Auvergne, UMR 454 INRAe, Microbiology, Digestive Environment and Health (MEDIS), Clermont-Ferrand, France
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14
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Wale KR, Cottam C, Connolly JP, Roe AJ. Transcriptional and metabolic regulation of EHEC and Citrobacter rodentium pathogenesis. Curr Opin Microbiol 2021; 63:70-75. [PMID: 34224961 DOI: 10.1016/j.mib.2021.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/04/2021] [Accepted: 06/16/2021] [Indexed: 11/24/2022]
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) is a gastrointestinal pathogen that colonizes the colonic epithelium of humans and ruminants using a Type Three Secretion System (T3SS). This system is indispensable for disease and is regulated in response to a plethora of host and microbiota derived signals. The murine pathogen, Citrobacter rodentium, has become an instrumental tool in studying EHEC infection mechanisms in vivo, given its natural ability to infect mice and reliance on the same colonisation machinery. Here, we provide a review of the most recent advancements in EHEC infection biology, focusing on transcriptional regulation of the T3SS in response to physiologically relevant signals and how colonisation impacts on the metabolic micro-environment of the host niche. We pay particular attention to studies that have employed the C. rodentium model for elucidation of such mechanisms in vivo.
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Affiliation(s)
- Kabo R Wale
- Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Curtis Cottam
- Newcastle University Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
| | - James Pr Connolly
- Newcastle University Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK
| | - Andrew J Roe
- Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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15
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The Canonical Long-Chain Fatty Acid Sensing Machinery Processes Arachidonic Acid To Inhibit Virulence in Enterohemorrhagic Escherichia coli. mBio 2021; 12:mBio.03247-20. [PMID: 33468701 PMCID: PMC7845647 DOI: 10.1128/mbio.03247-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Polyunsaturated fatty acids (PUFAs) play important roles in host immunity. Manipulation of lipid content in host tissues through diet or pharmacological interventions is associated with altered severity of various inflammatory diseases. The mammalian gastrointestinal tract is a complex biochemical organ that generates a diverse milieu of host- and microbe-derived metabolites. In this environment, bacterial pathogens sense and respond to specific stimuli, which are integrated into the regulation of their virulence programs. Previously, we identified the transcription factor FadR, a long-chain fatty acid (LCFA) acyl coenzyme A (acyl-CoA) sensor, as a novel virulence regulator in the human foodborne pathogen enterohemorrhagic Escherichia coli (EHEC). Here, we demonstrate that exogenous LCFAs directly inhibit the locus of enterocyte effacement (LEE) pathogenicity island in EHEC through sensing by FadR. Moreover, in addition to LCFAs that are 18 carbons in length or shorter, we introduce host-derived arachidonic acid (C20:4) as an additional LCFA that is recognized by the FadR system in EHEC. We show that arachidonic acid is processed by the acyl-CoA synthetase FadD, which permits binding to FadR and decreases FadR affinity for its target DNA sequences. This interaction enables the transcriptional regulation of FadR-responsive operons by arachidonic acid in EHEC, including the LEE. Finally, we show that arachidonic acid inhibits hallmarks of EHEC disease in a FadR-dependent manner, including EHEC attachment to epithelial cells and the formation of attaching and effacing lesions. Together, our findings delineate a molecular mechanism demonstrating how LCFAs can directly inhibit the virulence of an enteric bacterial pathogen. More broadly, our findings expand the repertoire of ligands sensed by the canonical LFCA sensing machinery in EHEC to include arachidonic acid, an important bioactive lipid that is ubiquitous within host environments.
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16
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A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression. Appl Environ Microbiol 2020; 86:AEM.00509-20. [PMID: 32358004 DOI: 10.1128/aem.00509-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.
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17
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Ellermann M, Pacheco AR, Jimenez AG, Russell RM, Cuesta S, Kumar A, Zhu W, Vale G, Martin SA, Raj P, McDonald JG, Winter SE, Sperandio V. Endocannabinoids Inhibit the Induction of Virulence in Enteric Pathogens. Cell 2020; 183:650-665.e15. [PMID: 33031742 DOI: 10.1016/j.cell.2020.09.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 06/30/2020] [Accepted: 09/08/2020] [Indexed: 12/12/2022]
Abstract
Endocannabinoids are host-derived lipid hormones that fundamentally impact gastrointestinal (GI) biology. The use of cannabis and other exocannabinoids as anecdotal treatments for various GI disorders inspired the search for mechanisms by which these compounds mediate their effects, which led to the discovery of the mammalian endocannabinoid system. Dysregulated endocannabinoid signaling was linked to inflammation and the gut microbiota. However, the effects of endocannabinoids on host susceptibility to infection has not been explored. Here, we show that mice with elevated levels of the endocannabinoid 2-arachidonoyl glycerol (2-AG) are protected from enteric infection by Enterobacteriaceae pathogens. 2-AG directly modulates pathogen function by inhibiting virulence programs essential for successful infection. Furthermore, 2-AG antagonizes the bacterial receptor QseC, a histidine kinase encoded within the core Enterobacteriaceae genome that promotes the activation of pathogen-associated type three secretion systems. Taken together, our findings establish that endocannabinoids are directly sensed by bacteria and can modulate bacterial function.
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Affiliation(s)
- Melissa Ellermann
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Alline R Pacheco
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Angel G Jimenez
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Regan M Russell
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Santiago Cuesta
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Aman Kumar
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wenhan Zhu
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gonçalo Vale
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sarah A Martin
- Department of Molecular Genetics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Prithvi Raj
- Microbiome Research Lab, Department of Immunology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jeffrey G McDonald
- Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sebastian E Winter
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vanessa Sperandio
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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18
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Abstract
Vibrio cholerae remains a challenge in the developing world and incidence of the disease it causes, cholera, is anticipated to increase with rising global temperatures and with emergent, highly infectious strains. At present, the underlying metabolic processes that support V. cholerae growth during infection are less well understood than specific virulence traits, such as production of a toxin or pilus. In this study, we determined that oxidative metabolism of host substrates such as mucin contribute significantly to V. cholerae population expansion in vivo. Identifying metabolic pathways critical for growth can provide avenues for controlling V. cholerae infection and the knowledge may be translatable to other pathogens of the gastrointestinal tract. Vibrio cholerae replicates to high cell density in the human small intestine, leading to the diarrheal disease cholera. During infection, V. cholerae senses and responds to environmental signals that govern cellular responses. Spatial localization of V. cholerae within the intestine affects nutrient availability and metabolic pathways required for replicative success. Metabolic processes used by V. cholerae to reach such high cell densities are not fully known. We sought to better define the metabolic traits that contribute to high levels of V. cholerae during infection. By disrupting the pyruvate dehydrogenase (PDH) complex and pyruvate formate-lyase (PFL), we could differentiate aerobic and anaerobic metabolic pathway involvement in V. cholerae proliferation. We demonstrate that oxidative metabolism is a key contributor to the replicative success of V. choleraein vivo using an infant mouse model in which PDH mutants were attenuated 100-fold relative to the wild type for colonization. Additionally, metabolism of host substrates, including mucin, was determined to support V. cholerae growth in vitro as a sole carbon source, primarily under aerobic growth conditions. Mucin likely contributes to population expansion during human infection as it is a ubiquitous source of carbohydrates. These data highlight oxidative metabolism as important in the intestinal environment and warrant further investigation of how oxygen and other host substrates shape the intestinal landscape that ultimately influences bacterial disease. We conclude from our results that oxidative metabolism of host substrates is a key driver of V. cholerae proliferation during infection, leading to the substantial bacterial burden exhibited in cholera patients.
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19
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Cadona JS, Burgán J, González J, Bustamante AV, Sanso AM. Differential expression of the virulence gene nleB among Shiga toxin-producing Escherichia coli strains. Heliyon 2020; 6:e04277. [PMID: 32613131 PMCID: PMC7322132 DOI: 10.1016/j.heliyon.2020.e04277] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/08/2020] [Accepted: 06/18/2020] [Indexed: 11/22/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a zoonotic foodborne pathogen associated with hemolytic uremic syndrome (HUS) that vary in their ability to cause disease in humans. STEC represents a serious problem for public health and Argentina is the country with the highest HUS incidence worldwide. Non-LEE effector (nle) genes, present on pathogenicity islands (PAIs), encode translocated substrates of the type III secretion system (T3SS), which could have an important role in STEC virulence. Particularly, nleB is one of the main effector genes proposed as a virulence marker that is involved in the action of T3SS during the STEC infection. NleB inhibits the inflammatory response of the host cell allowing the bacteria to persist in the first stage of the infection. In order to identify the potential risk of STEC strains for public health, the aim of this study was to evaluate and compare basal nleB transcription of 24 STEC strains belonging to 10 serotypes isolated from cattle, food and patients. The results showed differences in nleB transcription among strains. Some non-O157:H7 strains presented transcription levels above the control, an O157:H7 HUS-producing strain. On the other hand, no significant differences were found in basal transcription levels associated with origin or serotype but differences were found between HUS and non-HUS strains. These differences in nleB transcription may be of importance in STEC pathogenesis and could help to differentiate high and low virulence STEC strains.
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20
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Kumar A, Russell RM, Pifer R, Menezes-Garcia Z, Cuesta S, Narayanan S, MacMillan JB, Sperandio V. The Serotonin Neurotransmitter Modulates Virulence of Enteric Pathogens. Cell Host Microbe 2020; 28:41-53.e8. [PMID: 32521224 DOI: 10.1016/j.chom.2020.05.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/30/2020] [Accepted: 05/05/2020] [Indexed: 02/06/2023]
Abstract
The gut-brain axis is crucial to microbial-host interactions. The neurotransmitter serotonin is primarily synthesized in the gastrointestinal (GI) tract, where it is secreted into the lumen and subsequently removed by the serotonin transporter, SERT. Here, we show that serotonin decreases virulence gene expression by enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium, a murine model for EHEC. The membrane-bound histidine sensor kinase, CpxA, is a bacterial serotonin receptor. Serotonin induces dephosphorylation of CpxA, which inactivates the transcriptional factor CpxR controlling expression of virulence genes, notably those within the locus of enterocyte effacement (LEE). Increasing intestinal serotonin by genetically or pharmacologically inhibiting SERT decreases LEE expression and reduces C. rodentium loads. Conversely, inhibiting serotonin synthesis increases pathogenesis and decreases host survival. As other enteric bacteria contain CpxA, this signal exploitation may be engaged by other pathogens. Additionally, repurposing serotonin agonists to inhibit CpxA may represent a potential therapeutic intervention for enteric bacteria.
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Affiliation(s)
- Aman Kumar
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Regan M Russell
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Reed Pifer
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zelia Menezes-Garcia
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Santiago Cuesta
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sanjeev Narayanan
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506, USA
| | - John B MacMillan
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vanessa Sperandio
- Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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21
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l-Arginine sensing regulates virulence gene expression and disease progression in enteric pathogens. Proc Natl Acad Sci U S A 2020; 117:12387-12393. [PMID: 32409599 DOI: 10.1073/pnas.1919683117] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Microbiota, host and dietary metabolites/signals compose the rich gut chemical environment, which profoundly impacts virulence of enteric pathogens. Enterohemorrhagic Escherichia coli (EHEC) engages a syringe-like machinery named type-III secretion system (T3SS) to inject effectors within host cells that lead to intestinal colonization and disease. We previously conducted a high-throughput screen to identify metabolic pathways that affect T3SS expression. Here we show that in the presence of arginine, the arginine sensor ArgR, identified through this screen, directly activates expression of the genes encoding the T3SS. Exogenously added arginine induces EHEC virulence gene expression in vitro. Congruently, a mutant deficient in arginine transport (ΔartP) had decreased virulence gene expression. ArgR also augments murine disease caused by Citrobacter rodentium, which is a murine pathogen extensively employed as a surrogate animal model for EHEC. The source of arginine sensed by C. rodentium is not dietary. At the peak of C. rodentium infection, increased arginine concentration in the colon correlated with down-regulation of the host SLC7A2 transporter. This increase in the concentration of colonic arginine promotes virulence gene expression in C. rodentium Arginine is an important modulator of the host immune response to pathogens. Here we add that arginine also directly impacts bacterial virulence. These findings suggest that a delicate balance between host and pathogen responses to arginine occur during disease progression.
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22
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Jimenez AG, Ellermann M, Abbott W, Sperandio V. Diet-derived galacturonic acid regulates virulence and intestinal colonization in enterohaemorrhagic Escherichia coli and Citrobacter rodentium. Nat Microbiol 2019; 5:368-378. [PMID: 31873206 PMCID: PMC6992478 DOI: 10.1038/s41564-019-0641-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 11/11/2019] [Indexed: 12/21/2022]
Abstract
Enteric pathogens sense the complex chemistry within the gastrointestinal (GI) tract to efficiently compete with the resident microbiota and establish a colonization niche. Here we show that enterohemorrhagic E. coli (EHEC), and its surrogate murine infection model Citrobacter rodentium, sense galacturonic-acid to initiate a multi-layered program towards successful mammalian infection. Galacturonic-acid utilization as a carbon source aids the initial pathogen expansion. The main source of galacturonic-acid is dietary pectin, which is broken into galacturonic-acid by the prominent member of the microbiota, Bacteroides thetaiotamicron (Bt). This regulation occurs through the ExuR transcription factor. However, galacturonic-acid is also sensed as a signal through ExuR to modulate the expression of the genes encoding a molecular syringe known as a type three secretion system (T3SS) leading to infectious colitis and inflammation. Galacturonic-acid moonlights as a nutrient and a signal directing the exquisite microbiota-pathogen relationships within the GI tract. Importantly, this work highlights that differential dietary sugar availability impacts the relationship between the microbiota and enteric pathogens, as well as disease outcomes.
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Affiliation(s)
- Angel G Jimenez
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Melissa Ellermann
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada.,Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Vanessa Sperandio
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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23
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Woodward SE, Krekhno Z, Finlay BB. Here, there, and everywhere: How pathogenicEscherichia colisense and respond to gastrointestinal biogeography. Cell Microbiol 2019; 21:e13107. [DOI: 10.1111/cmi.13107] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Sarah E. Woodward
- Department of Microbiology and ImmunologyUniversity of British Columbia Vancouver British Columbia Canada
- Michael Smith LaboratoriesUniversity of British Columbia Vancouver British Columbia Canada
| | - Zakhar Krekhno
- Department of Microbiology and ImmunologyUniversity of British Columbia Vancouver British Columbia Canada
- Michael Smith LaboratoriesUniversity of British Columbia Vancouver British Columbia Canada
| | - B. Brett Finlay
- Department of Microbiology and ImmunologyUniversity of British Columbia Vancouver British Columbia Canada
- Michael Smith LaboratoriesUniversity of British Columbia Vancouver British Columbia Canada
- Department of Biochemistry and Molecular BiologyUniversity of British Columbia Vancouver British Columbia Canada
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24
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Reply to Wood and Lee, “Precedence for the Role of Indole with Pathogens”. mBio 2019; 10:mBio.01787-19. [PMID: 31363037 PMCID: PMC6667627 DOI: 10.1128/mbio.01787-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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25
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The sRNA DicF integrates oxygen sensing to enhance enterohemorrhagic Escherichia coli virulence via distinctive RNA control mechanisms. Proc Natl Acad Sci U S A 2019; 116:14210-14215. [PMID: 31235565 DOI: 10.1073/pnas.1902725116] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
To establish infection, enteric pathogens integrate environmental cues to navigate the gastrointestinal tract (GIT) and precisely control expression of virulence determinants. During passage through the GIT, pathogens encounter relatively high levels of oxygen in the small intestine before transit to the oxygen-limited environment of the colon. However, how bacterial pathogens sense oxygen availability and coordinate expression of virulence traits is not resolved. Here, we demonstrate that enterohemorrhagic Escherichia coli O157:H7 (EHEC) regulates virulence via the oxygen-responsive small RNA DicF. Under oxygen-limited conditions, DicF enhances global expression of the EHEC type three secretion system, which is a key virulence factor required for host colonization, through the transcriptional activator PchA. Mechanistically, the pchA coding sequence (CDS) base pairs with the 5' untranslated region of the mRNA to sequester the ribosome binding site (RBS) and inhibit translation. DicF disrupts pchA cis-interactions by binding to the pchA CDS, thereby unmasking the pchA RBS and promoting PchA expression. These findings uncover a feed-forward regulatory pathway that involves distinctive mechanisms of RNA-based regulation and that provides spatiotemporal control of EHEC virulence.
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26
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Tovaglieri A, Sontheimer-Phelps A, Geirnaert A, Prantil-Baun R, Camacho DM, Chou DB, Jalili-Firoozinezhad S, de Wouters T, Kasendra M, Super M, Cartwright MJ, Richmond CA, Breault DT, Lacroix C, Ingber DE. Species-specific enhancement of enterohemorrhagic E. coli pathogenesis mediated by microbiome metabolites. MICROBIOME 2019; 7:43. [PMID: 30890187 PMCID: PMC6425591 DOI: 10.1186/s40168-019-0650-5] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 02/21/2019] [Indexed: 05/24/2023]
Abstract
BACKGROUND Species-specific differences in tolerance to infection are exemplified by the high susceptibility of humans to enterohemorrhagic Escherichia coli (EHEC) infection, whereas mice are relatively resistant to this pathogen. This intrinsic species-specific difference in EHEC infection limits the translation of murine research to human. Furthermore, studying the mechanisms underlying this differential susceptibility is a difficult problem due to complex in vivo interactions between the host, pathogen, and disparate commensal microbial communities. RESULTS We utilize organ-on-a-chip (Organ Chip) microfluidic culture technology to model damage of the human colonic epithelium induced by EHEC infection, and show that epithelial injury is greater when exposed to metabolites derived from the human gut microbiome compared to mouse. Using a multi-omics approach, we discovered four human microbiome metabolites-4-methyl benzoic acid, 3,4-dimethylbenzoic acid, hexanoic acid, and heptanoic acid-that are sufficient to mediate this effect. The active human microbiome metabolites preferentially induce expression of flagellin, a bacterial protein associated with motility of EHEC and increased epithelial injury. Thus, the decreased tolerance to infection observed in humans versus other species may be due in part to the presence of compounds produced by the human intestinal microbiome that actively promote bacterial pathogenicity. CONCLUSION Organ-on-chip technology allowed the identification of specific human microbiome metabolites modulating EHEC pathogenesis. These identified metabolites are sufficient to increase susceptibility to EHEC in our human Colon Chip model and they contribute to species-specific tolerance. This work suggests that higher concentrations of these metabolites could be the reason for higher susceptibility to EHEC infection in certain human populations, such as children. Furthermore, this research lays the foundation for therapeutic-modulation of microbe products in order to prevent and treat human bacterial infection.
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Affiliation(s)
- Alessio Tovaglieri
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
- Department of Health Sciences and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Alexandra Sontheimer-Phelps
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
- Department of Biology, University of Freiburg, 79085, Freiburg, Germany
| | - Annelies Geirnaert
- Department of Health Sciences and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Rachelle Prantil-Baun
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Diogo M Camacho
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - David B Chou
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, 02115, USA
| | - Sasan Jalili-Firoozinezhad
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
- Department of Bioengineering and iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1649-004, Lisbon, Portugal
| | - Tomás de Wouters
- Department of Health Sciences and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Magdalena Kasendra
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
- Present Address: Emulate Inc., 27 Drydock Avenue, Boston, MA, 02210, USA
| | - Michael Super
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Mark J Cartwright
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Camilla A Richmond
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
- Harvard Stem Cell Institute, Harvard University, Boston, MA, 02139, USA
| | - David T Breault
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
- Harvard Stem Cell Institute, Harvard University, Boston, MA, 02139, USA
- Division of Endocrinology, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Christophe Lacroix
- Department of Health Sciences and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Donald E Ingber
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
- Vascular Biology Program and Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, USA.
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA, 02139, USA.
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Control freaks-signals and cues governing the regulation of virulence in attaching and effacing pathogens. Biochem Soc Trans 2018; 47:229-238. [PMID: 30559275 PMCID: PMC6393859 DOI: 10.1042/bst20180546] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/08/2018] [Accepted: 11/13/2018] [Indexed: 02/07/2023]
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) mediates disease using a type 3 secretion system (T3SS), which is encoded on the locus of enterocyte effacement (LEE) and is tightly controlled by master regulators. This system is further modulated by a number of signals that help to fine-tune virulence, including metabolic, environmental and chemical signals. Since the LEE and its master regulator, Ler, were established, there have been numerous scientific advancements in understanding the regulation and expression of virulence factors in EHEC. This review will discuss the recent advancements in this field since our previous review, with a focus on the transcriptional regulation of the LEE.
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Modulation of Enterohaemorrhagic Escherichia coli Survival and Virulence in the Human Gastrointestinal Tract. Microorganisms 2018; 6:microorganisms6040115. [PMID: 30463258 PMCID: PMC6313751 DOI: 10.3390/microorganisms6040115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/16/2018] [Accepted: 11/18/2018] [Indexed: 01/05/2023] Open
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) is a major foodborne pathogen responsible for human diseases ranging from diarrhoea to life-threatening complications. Survival of the pathogen and modulation of virulence gene expression along the human gastrointestinal tract (GIT) are key features in bacterial pathogenesis, but remain poorly described, due to a paucity of relevant model systems. This review will provide an overview of the in vitro and in vivo studies investigating the effect of abiotic (e.g., gastric acid, bile, low oxygen concentration or fluid shear) and biotic (e.g., gut microbiota, short chain fatty acids or host hormones) parameters of the human gut on EHEC survival and/or virulence (especially in relation with motility, adhesion and toxin production). Despite their relevance, these studies display important limitations considering the complexity of the human digestive environment. These include the evaluation of only one single digestive parameter at a time, lack of dynamic flux and compartmentalization, and the absence of a complex human gut microbiota. In a last part of the review, we will discuss how dynamic multi-compartmental in vitro models of the human gut represent a novel platform for elucidating spatial and temporal modulation of EHEC survival and virulence along the GIT, and provide new insights into EHEC pathogenesis.
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Redox, amino acid, and fatty acid metabolism intersect with bacterial virulence in the gut. Proc Natl Acad Sci U S A 2018; 115:E10712-E10719. [PMID: 30348782 DOI: 10.1073/pnas.1813451115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The gut metabolic landscape is complex and is influenced by the microbiota, host physiology, and enteric pathogens. Pathogens have to exquisitely monitor the biogeography of the gastrointestinal tract to find a suitable niche for colonization. To dissect the important metabolic pathways that influence virulence of enterohemorrhagic Escherichia coli (EHEC), we conducted a high-throughput screen. We generated a dataset of regulatory pathways that control EHEC virulence expression under anaerobic conditions. This unraveled that the cysteine-responsive regulator, CutR, converges with the YhaO serine import pump and the fatty acid metabolism regulator FadR to optimally control virulence expression in EHEC. CutR activates expression of YhaO to increase activity of the YhaJ transcription factor that has been previously shown to directly activate the EHEC virulence genes. CutR enhances FadL, which is a pump for fatty acids that represses inhibition of virulence expression by FadR, unmasking a feedback mechanism responsive to metabolite fluctuations. Moreover, CutR and FadR also augment murine infection by Citrobacter rodentium, which is a murine pathogen extensively employed as a surrogate animal model for EHEC. This high-throughput approach proved to be a powerful tool to map the web of cellular circuits that allows an enteric pathogen to monitor the gut environment and adjust the levels of expression of its virulence repertoire toward successful infection of the host.
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Host-associated niche metabolism controls enteric infection through fine-tuning the regulation of type 3 secretion. Nat Commun 2018; 9:4187. [PMID: 30305622 PMCID: PMC6180029 DOI: 10.1038/s41467-018-06701-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 09/14/2018] [Indexed: 12/31/2022] Open
Abstract
Niche-adaptation of a bacterial pathogen hinges on the ability to recognize the complexity of signals from the environment and integrate that information with the regulation of genes critical for infection. Here we report the transcriptome of the attaching and effacing pathogen Citrobacter rodentium during infection of its natural murine host. Pathogen gene expression in vivo was heavily biased towards the virulence factor repertoire and was found to be co-ordinated uniquely in response to the host. Concordantly, we identified the host-specific induction of a metabolic pathway that overlapped with the regulation of virulence. The essential type 3 secretion system and an associated suite of distinct effectors were found to be modulated co-ordinately through a unique mechanism involving metabolism of microbiota-derived 1,2-propanediol, which dictated the ability to colonize the host effectively. This study provides novel insights into how host-specific metabolic adaptation acts as a cue to fine-tune virulence. Infection of mice with Citrobacter rodentium is a common model of infection with attaching-and-effacing pathogens. Here, Connolly et al. analyse the transcriptome of C. rodentium during mouse infection, showing host-induced coordinated upregulation of virulence factors and 1,2-propanediol metabolism.
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31
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Affiliation(s)
- Vanessa Sperandio
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9048;
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas TX 75390-9048
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32
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The Catabolite Repressor/Activator Cra Is a Bridge Connecting Carbon Metabolism and Host Colonization in the Plant Drought Resistance-Promoting Bacterium Pantoea alhagi LTYR-11Z. Appl Environ Microbiol 2018; 84:AEM.00054-18. [PMID: 29703735 DOI: 10.1128/aem.00054-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/20/2018] [Indexed: 12/22/2022] Open
Abstract
Efficient root colonization is a prerequisite for application of plant growth-promoting (PGP) bacteria in improving health and yield of agricultural crops. We have recently identified an endophytic bacterium, Pantoea alhagi LTYR-11Z, with multiple PGP properties that effectively colonizes the root system of wheat and improves its growth and drought tolerance. To identify novel regulatory genes required for wheat colonization, we screened an LTYR-11Z transposon (Tn) insertion library and found cra to be a colonization-related gene. By using transcriptome (RNA-seq) analysis, we found that transcriptional levels of an eps operon, the ydiV gene encoding an anti-FlhD4C2 factor, and the yedQ gene encoding an enzyme for synthesis of cyclic dimeric GMP (c-di-GMP) were significantly downregulated in the Δcra mutant. Further studies demonstrated that Cra directly binds to the promoters of the eps operon, ydiV, and yedQ and activates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production and biofilm formation. Consistent with previous findings that Cra plays a role in transcriptional regulation in response to carbon source availability, the activating effects of Cra were much more pronounced when LTYR-11Z was grown within a gluconeogenic environment than when it was grown within a glycolytic environment. We further demonstrate that the ability of LTYR-11Z to colonize wheat roots is modulated by the availability of carbon sources. Altogether, these results uncover a novel strategy utilized by LTYR-11Z to achieve host colonization in response to carbon nutrition in the environment, in which Cra bridges a connection between carbon metabolism and colonization capacity of LTYR-11Z.IMPORTANCE Rapid and appropriate response to environmental signals is crucial for bacteria to adapt to competitive environments and to establish interactions with their hosts. Efficient colonization and persistence within the host are controlled by various regulatory factors that respond to specific environmental cues. The most common is nutrient availability. In this work, we unraveled the pivotal role of Cra in regulation of colonization ability of Pantoea alhagi LTYR-11Z in response to carbon source availability. Moreover, we identified three novel members of the Cra regulon involved in EPS synthesis, regulation of flagellar biosynthesis, and synthesis of c-di-GMP and propose a working model to explain the Cra-mediated regulatory mechanism that links carbon metabolism to host colonization. This study elucidates the regulatory role of Cra in bacterial attachment and colonization of plants, which raises the possibility of extending our studies to other bacteria associated with plant and human health.
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Kuo CJ, Wang ST, Lin CM, Chiu HC, Huang CR, Lee DY, Chang GD, Chou TC, Chen JW, Chen CS. A multi-omic analysis reveals the role of fumarate in regulating the virulence of enterohemorrhagic Escherichia coli. Cell Death Dis 2018. [PMID: 29515100 PMCID: PMC5841434 DOI: 10.1038/s41419-018-0423-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The enteric pathogen enterohemorrhagic Escherichia coli (EHEC) is responsible for outbreaks of bloody diarrhea and hemolytic uremic syndrome (HUS) worldwide. Several molecular mechanisms have been described for the pathogenicity of EHEC; however, the role of bacterial metabolism in the virulence of EHEC during infection in vivo remains unclear. Here we show that aerobic metabolism plays an important role in the regulation of EHEC virulence in Caenorhabditis elegans. Our functional genomic analyses showed that disruption of the genes encoding the succinate dehydrogenase complex (Sdh) of EHEC, including the sdhA gene, attenuated its toxicity toward C. elegans animals. Sdh converts succinate to fumarate and links the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC) simultaneously. Succinate accumulation and fumarate depletion in the EHEC sdhA mutant cells were also demonstrated to be concomitant by metabolomic analyses. Moreover, fumarate replenishment to the sdhA mutant significantly increased its virulence toward C. elegans. These results suggest that the TCA cycle, ETC, and alteration in metabolome all account for the attenuated toxicity of the sdhA mutant, and Sdh catabolite fumarate in particular plays a critical role in the regulation of EHEC virulence. In addition, we identified the tryptophanase (TnaA) as a downstream virulence determinant of SdhA using a label-free proteomic method. We demonstrated that expression of tnaA is regulated by fumarate in EHEC. Taken together, our multi-omic analyses demonstrate that sdhA is required for the virulence of EHEC, and aerobic metabolism plays important roles in the pathogenicity of EHEC infection in C. elegans. Moreover, our study highlights the potential targeting of SdhA, if druggable, as alternative preventive or therapeutic strategies by which to combat EHEC infection.
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Affiliation(s)
- Cheng-Ju Kuo
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Sin-Tian Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chia-Mei Lin
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Hao-Chieh Chiu
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Cheng-Rung Huang
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Der-Yen Lee
- The Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan.,Graduate Institute of Biochemical Sciences, Technology Commons, Center for Systems Biology, National Taiwan University, Taipei, Taiwan
| | - Geen-Dong Chang
- Graduate Institute of Biochemical Sciences, Technology Commons, Center for Systems Biology, National Taiwan University, Taipei, Taiwan
| | - Ting-Chen Chou
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jenn-Wei Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. .,Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
| | - Chang-Shi Chen
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. .,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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34
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Abstract
Enteric pathogens with low infectious doses rely on the ability to orchestrate the expression of virulence and metabolism-associated genes in response to environmental cues for successful infection. Accordingly, the human pathogen enterohemorrhagic Escherichia coli (EHEC) employs a complex multifaceted regulatory network to link the expression of type III secretion system (T3SS) components to nutrient availability. While phosphorylation of histidine and aspartate residues on two-component system response regulators is recognized as an integral part of bacterial signaling, the involvement of phosphotyrosine-mediated control is minimally explored in Gram-negative pathogens. Our recent phosphotyrosine profiling study of E. coli identified 342 phosphorylated proteins, indicating that phosphotyrosine modifications in bacteria are more prevalent than previously anticipated. The present study demonstrates that tyrosine phosphorylation of a metabolite-responsive LacI/GalR family regulator, Cra, negatively affects T3SS expression under glycolytic conditions that are typical for the colonic lumen environment where production of the T3SS is unnecessary. Our data suggest that Cra phosphorylation affects T3SS expression by modulating the expression of ler, which encodes the major activator of EHEC virulence gene expression. Phosphorylation of the Cra Y47 residue diminishes DNA binding to fine-tune the expression of virulence-associated genes, including those of the locus of enterocyte effacement pathogenicity island that encode the T3SS, and thereby negatively affects the formation of attaching and effacing lesions. Our data indicate that tyrosine phosphorylation provides an additional mechanism to control the DNA binding of Cra and other LacI/GalR family regulators, including LacI and PurR. This study describes an initial effort to unravel the role of global phosphotyrosine signaling in the control of EHEC virulence potential. Enterohemorrhagic Escherichia coli (EHEC) causes outbreaks of hemorrhagic colitis and the potentially fatal hemolytic-uremic syndrome. Successful host colonization by EHEC relies on the ability to coordinate the expression of virulence factors in response to environmental cues. A complex network that integrates environmental signals at multiple regulatory levels tightly controls virulence gene expression. We demonstrate that EHEC utilizes a previously uncharacterized phosphotyrosine signaling pathway through Cra to fine-tune the expression of virulence-associated genes to effectively control T3SS production. This study demonstrates that tyrosine phosphorylation negatively affects the DNA-binding capacity of Cra, which affects the expression of genes related to virulence and metabolism. We demonstrate for the first time that phosphotyrosine-mediated control affects global transcription in EHEC. Our data provide insight into a hitherto unexplored regulatory level of the global network controlling EHEC virulence gene expression.
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Carlson-Banning KM, Sperandio V. Enterohemorrhagic Escherichia coli outwits hosts through sensing small molecules. Curr Opin Microbiol 2018; 41:83-88. [PMID: 29258058 PMCID: PMC5862742 DOI: 10.1016/j.mib.2017.12.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/29/2017] [Accepted: 12/05/2017] [Indexed: 02/07/2023]
Abstract
Small molecules help intestinal pathogens navigate the complex human gastrointestinal tract to exploit favorable microhabitats. These small molecules provide spatial landmarks for pathogens to regulate synthesis of virulence caches and are derived from the host, ingested plant and animal material, and the microbiota. Their concentrations and fluxes vary along the length of the gut and provide molecular signatures that are beginning to be explored through metabolomics and genetics. However, while many small molecules have been identified and are reviewed here, there are undoubtedly others that may also profoundly affect how enteric pathogens infect their hosts.
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Affiliation(s)
- Kimberly M Carlson-Banning
- Departments of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Vanessa Sperandio
- Departments of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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36
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Regulation of the Locus of Enterocyte Effacement in Attaching and Effacing Pathogens. J Bacteriol 2017; 200:JB.00336-17. [PMID: 28760850 DOI: 10.1128/jb.00336-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Attaching and effacing (AE) pathogens colonize the gut mucosa using a type three secretion system (T3SS) and a suite of effector proteins. The locus of enterocyte effacement (LEE) is the defining genetic feature of the AE pathogens, encoding the T3SS and the core effector proteins necessary for pathogenesis. Extensive research has revealed a complex regulatory network that senses and responds to a myriad of host- and microbiota-derived signals in the infected gut to control transcription of the LEE. These signals include microbiota-liberated sugars and metabolites in the gut lumen, molecular oxygen at the gut epithelium, and host hormones. Recent research has revealed that AE pathogens also recognize physical signals, such as attachment to the epithelium, and that the act of effector translocation remodels gene expression in infecting bacteria. In this review, we summarize our knowledge to date and present an integrated view of how chemical, geographical, and physical cues regulate the virulence program of AE pathogens during infection.
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37
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Bacterial Chat: Intestinal Metabolites and Signals in Host-Microbiota-Pathogen Interactions. Infect Immun 2017; 85:IAI.00476-17. [PMID: 28947641 DOI: 10.1128/iai.00476-17] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Intestinal bacteria employ microbial metabolites from the microbiota and chemical signaling during cell-to-cell communication to regulate several cellular functions. Pathogenic bacteria are extremely efficient in orchestrating their response to these signals through complex signaling transduction systems. Precise coordination and interpretation of these multiple chemical cues is important within the gastrointestinal (GI) tract. Enteric foodborne pathogens, such as enterohemorrhagic Escherichia coli (EHEC) and Salmonella enterica serovar Typhimurium, or the surrogate murine infection model for EHEC, Citrobacter rodentium, are all examples of microorganisms that modulate the expression of their virulence repertoire in response to signals from the microbiota or the host, such as autoinducer-3 (AI-3), epinephrine (Epi), and norepinephrine (NE). The QseBC and QseEF two-component systems, shared by these pathogens, are involved in sensing these signals. We review how these signaling systems sense and relay these signals to drive bacterial gene expression; specifically, to modulate virulence. We also review how bacteria chat via chemical signals integrated with metabolite recognition and utilization to promote successful associations among enteric pathogens, the microbiota, and the host.
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38
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Citrobacter rodentium Subverts ATP Flux and Cholesterol Homeostasis in Intestinal Epithelial Cells In Vivo. Cell Metab 2017; 26:738-752.e6. [PMID: 28988824 PMCID: PMC5695859 DOI: 10.1016/j.cmet.2017.09.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/18/2017] [Accepted: 09/06/2017] [Indexed: 01/12/2023]
Abstract
The intestinal epithelial cells (IECs) that line the gut form a robust line of defense against ingested pathogens. We investigated the impact of infection with the enteric pathogen Citrobacter rodentium on mouse IEC metabolism using global proteomic and targeted metabolomics and lipidomics. The major signatures of the infection were upregulation of the sugar transporter Sglt4, aerobic glycolysis, and production of phosphocreatine, which mobilizes cytosolic energy. In contrast, biogenesis of mitochondrial cardiolipins, essential for ATP production, was inhibited, which coincided with increased levels of mucosal O2 and a reduction in colon-associated anaerobic commensals. In addition, IECs responded to infection by activating Srebp2 and the cholesterol biosynthetic pathway. Unexpectedly, infected IECs also upregulated the cholesterol efflux proteins AbcA1, AbcG8, and ApoA1, resulting in higher levels of fecal cholesterol and a bloom of Proteobacteria. These results suggest that C. rodentium manipulates host metabolism to evade innate immune responses and establish a favorable gut ecosystem.
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39
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Sicard JF, Le Bihan G, Vogeleer P, Jacques M, Harel J. Interactions of Intestinal Bacteria with Components of the Intestinal Mucus. Front Cell Infect Microbiol 2017; 7:387. [PMID: 28929087 PMCID: PMC5591952 DOI: 10.3389/fcimb.2017.00387] [Citation(s) in RCA: 279] [Impact Index Per Article: 39.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/18/2017] [Indexed: 12/19/2022] Open
Abstract
The human gut is colonized by a variety of large amounts of microbes that are collectively called intestinal microbiota. Most of these microbial residents will grow within the mucus layer that overlies the gut epithelium and will act as the first line of defense against both commensal and invading microbes. This mucus is essentially formed by mucins, a family of highly glycosylated protein that are secreted by specialize cells in the gut. In this Review, we examine how commensal members of the microbiota and pathogenic bacteria use mucus to their advantage to promote their growth, develop biofilms and colonize the intestine. We also discuss how mucus-derived components act as nutrient and chemical cues for adaptation and pathogenesis of bacteria and how bacteria can influence the composition of the mucus layer.
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Affiliation(s)
- Jean-Félix Sicard
- Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de MontréalSaint-Hyacinthe, QC, Canada
| | - Guillaume Le Bihan
- Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de MontréalSaint-Hyacinthe, QC, Canada
| | - Philippe Vogeleer
- Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de MontréalSaint-Hyacinthe, QC, Canada
| | - Mario Jacques
- Regroupement de Recherche Pour un Lait de Qualité Optimale (Op+Lait), Faculté de Médecine Vétérinaire, Université de MontréalSaint-Hyacinthe, QC, Canada
| | - Josée Harel
- Centre de Recherche en Infectiologie Porcine et Aviaire, Faculté de Médecine Vétérinaire, Université de MontréalSaint-Hyacinthe, QC, Canada
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40
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Genetic and Mechanistic Analyses of the Periplasmic Domain of the Enterohemorrhagic Escherichia coli QseC Histidine Sensor Kinase. J Bacteriol 2017; 199:JB.00861-16. [PMID: 28138098 DOI: 10.1128/jb.00861-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 01/23/2017] [Indexed: 12/23/2022] Open
Abstract
The histidine sensor kinase (HK) QseC senses autoinducer 3 (AI-3) and the adrenergic hormones epinephrine and norepinephrine. Upon sensing these signals, QseC acts through three response regulators (RRs) to regulate the expression of virulence genes in enterohemorrhagic Escherichia coli (EHEC). The QseB, QseF, and KdpE RRs that are phosphorylated by QseC constitute a tripartite signaling cascade having different and overlapping targets, including flagella and motility, the type three secretion system encoded by the locus of enterocyte effacement (LEE), and Shiga toxin. We modeled the tertiary structure of QseC's periplasmic sensing domain and aligned the sequences from 12 different species to identify the most conserved amino acids. We selected eight amino acids conserved in all of these QseC homologues. The corresponding QseC site-directed mutants were expressed and still able to autophosphorylate; however, four mutants demonstrated an increased basal level of phosphorylation. These mutants have differential flagellar, motility, LEE, and Shiga toxin expression phenotypes. We selected four mutants for more in-depth analyses and found that they differed in their ability to phosphorylate QseB, KdpE, and QseF. This suggests that these mutations in the periplasmic sensing domain affected the region downstream of the QseC signaling cascade and therefore can influence which pathway QseC regulates.IMPORTANCE In the foodborne pathogen EHEC, QseC senses AI-3, epinephrine, and norepinephrine, increases its autophosphorylation, and then transfers its phosphate to three RRs: QseB, QseF, and KdpE. QseB controls expression of flagella and motility, KdpE controls expression of the LEE region, and QseF controls the expression of Shiga toxin. This tripartite signaling pathway must be tightly controlled, given that flagella and the type three secretion system (T3SS) are energetically expensive appendages and Shiga toxin expression leads to bacterial cell lysis. Our data suggest that mutations in the periplasmic sensing loop of QseC differentially affect the expression of the three arms of this signaling cascade. This suggests that these point mutations may change QseC's phosphotransfer preferences for its RRs.
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