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Wang F, Sun H, Kang C, Yan J, Chen J, Feng X, Yang B. Genomic island-encoded regulatory proteins in enterohemorrhagic Escherichia coli O157:H7. Virulence 2024; 15:2313407. [PMID: 38357901 PMCID: PMC10877973 DOI: 10.1080/21505594.2024.2313407] [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: 10/24/2023] [Accepted: 01/23/2024] [Indexed: 02/16/2024] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is an important zoonotic pathogen that is a major cause of foodborne diseases in most developed and developing countries and can cause uncomplicated diarrhoea, haemorrhagic colitis, and haemolytic uraemic syndrome. O islands (OIs), which are unique genomic islands in EHEC O157:H7, are composed of 177 isolated genomic features and harbour 26% of the total genes that are absent in the non-pathogenic E. coli K-12 genome. In the last twenty years, many OI-encoded proteins have been characterized, including proteins regulating virulence, motility, and acid resistance. Given the critical role of regulatory proteins in the systematic and hierarchical regulation of bacterial biological processes, this review summarizes the OI-encoded regulatory proteins in EHEC O157:H7 characterized to date, emphasizing OI-encoded regulatory proteins for bacterial virulence, motility, and acid resistance. This summary will be significant for further exploration and understanding of the virulence and pathogenesis of EHEC O157:H7.
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Affiliation(s)
- Fang Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
- Intensive Care Unit, Shenzhen Institute of Translational Medicine, Health Science Center, The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Hongmin Sun
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Chenbo Kang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Jun Yan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Jingnan Chen
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Xuequan Feng
- Tianjin First Central Hospital, Nankai University, Tianjin, China
| | - Bin Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
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Schumacher K, Braun D, Kleigrewe K, Jung K. Motility-activating mutations upstream of flhDC reduce acid shock survival of Escherichia coli. Microbiol Spectr 2024; 12:e0054424. [PMID: 38651876 DOI: 10.1128/spectrum.00544-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024] Open
Abstract
Many neutralophilic bacterial species try to evade acid stress with an escape strategy, which is reflected in the increased expression of genes coding for flagellar components. Extremely acid-tolerant bacteria, such as Escherichia coli, survive the strong acid stress, e.g., in the stomach of vertebrates. Recently, we were able to show that the induction of motility genes in E. coli is strictly dependent on the degree of acid stress, i.e., they are induced under mild acid stress but not under severe acid stress. However, it was not known to what extent fine-tuned expression of motility genes is related to fitness and the ability to survive periods of acid shock. In this study, we demonstrate that the expression of FlhDC, the master regulator of flagellation, is inversely correlated with the acid shock survival of E. coli. We encountered this phenomenon when analyzing mutants from the Keio collection, in which the expression of flhDC was altered by an insertion sequence element. These results suggest a fitness trade-off between acid tolerance and motility.IMPORTANCEEscherichia coli is extremely acid-resistant, which is crucial for survival in the gastrointestinal tract of vertebrates. Recently, we systematically studied the response of E. coli to mild and severe acidic conditions using Ribo-Seq and RNA-Seq. We found that motility genes are induced at pH 5.8 but not at pH 4.4, indicating stress-dependent synthesis of flagellar components. In this study, we demonstrate that motility-activating mutations upstream of flhDC, encoding the master regulator of flagella genes, reduce the ability of E. coli to survive periods of acid shock. Furthermore, we show an inverse correlation between motility and acid survival using a chromosomal isopropyl β-D-thio-galactopyranoside (IPTG)-inducible flhDC promoter and by sampling differentially motile subpopulations from swim agar plates. These results reveal a previously undiscovered trade-off between motility and acid tolerance and suggest a differentiation of E. coli into motile and acid-tolerant subpopulations, driven by the integration of insertion sequence elements.
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Affiliation(s)
- Kilian Schumacher
- Faculty of Biology, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Djanna Braun
- Faculty of Biology, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Karin Kleigrewe
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), Technical University of Munich, Freising, Germany
| | - Kirsten Jung
- Faculty of Biology, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
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Chakkour M, Hammoud Z, Farhat S, El Roz A, Ezzeddine Z, Ghssein G. Overview of Proteus mirabilis pathogenicity and virulence. Insights into the role of metals. Front Microbiol 2024; 15:1383618. [PMID: 38646633 PMCID: PMC11026637 DOI: 10.3389/fmicb.2024.1383618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 03/15/2024] [Indexed: 04/23/2024] Open
Abstract
Proteus mirabilis is a Gram-negative bacterium with exclusive molecular and biological features. It is a versatile pathogen acclaimed for its distinct urease production, swarming behavior, and rapid multicellular activity. Clinically, P. mirabilis is a frequent pathogen of the human urinary system where it causes urinary tract infections (UTIs) and catheter-associated urinary tract infections (CAUTIs). This review explores the epidemiology, risk factors, clinical manifestations, and treatment of P. mirabilis infections, emphasizing its association with UTIs. The bacterium's genome analysis revealed the presence of resistance genes against commonly used antibiotics, an antibiotic-resistant phenotype that poses a serious clinical challenge. Particularly, the emergence of extended-spectrum β-lactamases (ESBLs) and carbapenemases resistant P. mirabilis strains. On a molecular level, P. mirabilis possesses a wide array of virulence factors including the production of fimbriae, urease, hemolysins, metallophores, and biofilm formation. This review thoroughly tackles a substantial gap in understanding the role of metallophores in shaping the virulence factors of P. mirabilis virulence. Siderophores, iron metal chelating and transporting metallophores, particularly contribute to the complex pathogenic strategies, displaying a potential target for therapeutic intervention.
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Affiliation(s)
- Mohamed Chakkour
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Zeinab Hammoud
- Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Solay Farhat
- Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Ali El Roz
- Laboratory Sciences Department, Faculty of Public Health, Islamic University of Lebanon (IUL), Khalde, Lebanon
| | - Zeinab Ezzeddine
- Laboratory Sciences Department, Faculty of Public Health, Islamic University of Lebanon (IUL), Khalde, Lebanon
| | - Ghassan Ghssein
- Laboratory Sciences Department, Faculty of Public Health, Islamic University of Lebanon (IUL), Khalde, Lebanon
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Murata T, Gotoh Y, Hayashi T. A comprehensive list of genes required for the efficient conjugation of plasmid Rts1 was determined by systematic deletion analysis. DNA Res 2024; 31:dsae002. [PMID: 38300630 PMCID: PMC10838148 DOI: 10.1093/dnares/dsae002] [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: 11/27/2023] [Revised: 01/08/2024] [Accepted: 01/31/2024] [Indexed: 02/02/2024] Open
Abstract
While conjugation-related genes have been identified in many plasmids by genome sequencing, functional analyses have not yet been performed in most cases, and a full set of conjugation genes has been identified for only a few plasmids. Rts1, a prototype IncT plasmid, is a conjugative plasmid that was originally isolated from Proteus vulgaris. Here, we conducted a systematic deletion analysis of Rts1 to fully understand its conjugation system. Through this analysis along with complementation assays, we identified 32 genes that are required for the efficient conjugation of Rts1 from Escherichia coli to E. coli. In addition, the functions of the 28 genes were determined or predicted; 21 were involved in mating-pair formation, three were involved in DNA transfer and replication, including a relaxase gene belonging to the MOBH12 family, one was involved in coupling, and three were involved in transcriptional regulation. Among the functionally well-analysed conjugation systems, most of the 28 genes showed the highest similarity to those of the SXT element, which is an integrative conjugative element of Vibrio cholerae. The Rts1 conjugation gene set included all 23 genes required for the SXT system. Two groups of plasmids with conjugation systems nearly identical or very similar to that of Rts1 were also identified.
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Affiliation(s)
- Takahiro Murata
- Department of Pediatrics, Teikyo University School of Medicine, Mizonokuchi Hospital, Takatsu-ku, Kawasaki, Kanagawa 213-8507, Japan
| | - Yasuhiro Gotoh
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
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Han S, Byun JW, Lee M. Comparative Transcriptomic Analysis of Flagellar-Associated Genes in Salmonella Typhimurium and Its rnc Mutant. J Microbiol 2024; 62:33-48. [PMID: 38182942 DOI: 10.1007/s12275-023-00099-5] [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: 09/27/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 01/07/2024]
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is a globally recognized foodborne pathogen that affects both animals and humans. Endoribonucleases mediate RNA processing and degradation in the adaptation of bacteria to environmental changes and have been linked to the pathogenicity of S. Typhimurium. Not much is known about the specific regulatory mechanisms of these enzymes in S. Typhimurium, particularly in the context of environmental adaptation. Thus, this study carried out a comparative transcriptomic analysis of wild-type S. Typhimurium SL1344 and its mutant (∆rnc), which lacks the rnc gene encoding RNase III, thereby elucidating the detailed regulatory characteristics that can be attributed to the rnc gene. Global gene expression analysis revealed that the ∆rnc strain exhibited 410 upregulated and 301 downregulated genes (fold-change > 1.5 and p < 0.05), as compared to the wild-type strain. Subsequent bioinformatics analysis indicated that these differentially expressed genes are involved in various physiological functions, in both the wild-type and ∆rnc strains. This study provides evidence for the critical role of RNase III as a general positive regulator of flagellar-associated genes and its involvement in the pathogenicity of S. Typhimurium.
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Affiliation(s)
- Seungmok Han
- Department of Microbiology, College of Medicine, Hallym University, Chuncheon, 24252, Republic of Korea
| | - Ji-Won Byun
- Department of Microbiology, College of Medicine, Hallym University, Chuncheon, 24252, Republic of Korea
| | - Minho Lee
- Department of Microbiology, College of Medicine, Hallym University, Chuncheon, 24252, Republic of Korea.
- Institute of Medical Science, College of Medicine, Hallym University, Chuncheon, 24252, Republic of Korea.
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Huang S, Li Y, Hong C, Jin Y, Li S, Xu X, Xia Y, Zhang L, Lou Y, Guan W. Whole-genome sequencing-based analysis of antimicrobial resistance, virulence factors, and genetic diversity in Yersinia isolated in Wenzhou, China 2020. Mol Phylogenet Evol 2023; 188:107903. [PMID: 37574177 DOI: 10.1016/j.ympev.2023.107903] [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: 03/30/2023] [Revised: 07/20/2023] [Accepted: 08/10/2023] [Indexed: 08/15/2023]
Abstract
Yersinia spp. vary significantly in their ability to cause diseases that threaten public health. Their pathogenicity is frequently associated with increasing antimicrobial resistance (AMR) and various virulence factors. The aim of the study was to investigate the AMR genes, virulence factors, and genetic diversity of Yersinia strains isolated from meats and fish in Wenzhou in 2020 by using whole-genome sequencing (WGS). A total of 50 isolates were collected. The phylogenetic relationships among the Yersinia species were also analyzed using multilocus sequence typing (MLST), core genome multi-locus sequence typing (cgMLST), and single nucleotide polymorphism (SNP) analysis. According to the results, all the strains could be classified into five species, with most isolated from beef, followed by poultry, pork, and fish. AMR genes were identified in 23 strains. And the qnrD1 genes were all located in the Col3M plasmid. Virulence genes, such as yaxA, ystB, pla, and yplA, were also found in the 15 Y. enterocolitica strains. And this study also found the presence of icm/dot type IVB-related genes in one Yersinia massiliensis isolate. MLST analysis identified 43 sequence types (STs), 19 of which were newly detected in Yersinia. Moreover, cgMLST analysis revealed that no dense genotype clusters were formed (cgMLST 5341, 5344, 5346-5350, 5353-5390). Instead, the strains appeared to be dispersed over large distances, except when multiple isolates shared the same ST. Isolates Y4 and Y26 were closely related to strains originating from South Korea and Denmark. This study showed considerable diversity in Yersinia spp. isolated from local areas (Wenzhou City). The data generated in our study may enrich the molecular traceability database of Yersinia and provide a basis for the development of more effective antipathogen control strategies.
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Affiliation(s)
- Shaojie Huang
- Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
| | - Yi Li
- Wenzhou Center for Disease Control and Prevention, Wenzhou, China.
| | - Chengji Hong
- Wenzhou Center for Disease Control and Prevention, Wenzhou, China.
| | - Yafang Jin
- Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
| | - Shengkai Li
- Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
| | - Xuelian Xu
- Yuhang Center for Disease Control and Prevention, Yuhang, China.
| | - Yanmei Xia
- Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
| | - Leyi Zhang
- Wenzhou Center for Disease Control and Prevention, Wenzhou, China.
| | - Yongliang Lou
- Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
| | - Wanchun Guan
- Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.
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Maldonado J, Czarnecka B, Harmon DE, Ruiz C. The multidrug efflux pump regulator AcrR directly represses motility in Escherichia coli. mSphere 2023; 8:e0043023. [PMID: 37787551 PMCID: PMC10597343 DOI: 10.1128/msphere.00430-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 08/18/2023] [Indexed: 10/04/2023] Open
Abstract
Efflux and motility are two key biological functions in bacteria. Recent findings have shown that efflux impacts flagellum biosynthesis and motility in Escherichia coli and other bacteria. AcrR is known to be the major transcriptional repressor of AcrAB-TolC, the main multidrug efflux pump in E. coli and other Enterobacteriaceae. However, the underlying molecular mechanisms of how efflux and motility are co-regulated remain poorly understood. Here, we have studied the role of AcrR in direct regulation of motility in E. coli. By combining bioinformatics, electrophoretic mobility shift assays (EMSAs), gene expression, and motility experiments, we have found that AcrR represses motility in E. coli by directly repressing transcription of the flhDC operon, but not the other flagellum genes/operons tested. flhDC encodes the master regulator of flagellum biosynthesis and motility genes. We found that such regulation primarily occurs by direct binding of AcrR to the flhDC promoter region containing the first of the two predicted AcrR-binding sites identified in this promoter. This is the first report of direct regulation by AcrR of genes unrelated to efflux or detoxification. Moreover, we report that overexpression of AcrR restores to parental levels the increased swimming motility previously observed in E. coli strains without a functional AcrAB-TolC pump, and that such effect by AcrR is prevented by the AcrR ligand and AcrAB-TolC substrate ethidium bromide. Based on these and prior findings, we provide a novel model in which AcrR senses efflux and then co-regulates efflux and motility in E. coli to maintain homeostasis and escape hazards. IMPORTANCE Efflux and motility play a major role in bacterial growth, colonization, and survival. In Escherichia coli, the transcriptional repressor AcrR is known to directly repress efflux and was later found to also repress flagellum biosynthesis and motility by Kim et al. (J Microbiol Biotechnol 26:1824-1828, 2016, doi: 10.4014/jmb.1607.07058). However, it remained unknown whether AcrR represses flagellum biosynthesis and motility directly and through which target genes, or indirectly because of altering the amount of efflux. This study reveals that AcrR represses flagellum biosynthesis and motility by directly repressing the expression of the flhDC master regulator of flagellum biosynthesis and motility genes, but not the other flagellum genes tested. We also show that the antimicrobial, efflux pump substrate, and AcrR ligand ethidium bromide regulates motility via AcrR. Overall, these findings support a novel model of direct co-regulation of efflux and motility mediated by AcrR in response to stress in E. coli.
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Affiliation(s)
- Jessica Maldonado
- Department of Biology, California State University Northridge, Northridge, California, USA
| | - Barbara Czarnecka
- Department of Biology, California State University Northridge, Northridge, California, USA
| | - Dana E. Harmon
- Department of Biology, California State University Northridge, Northridge, California, USA
| | - Cristian Ruiz
- Department of Biology, California State University Northridge, Northridge, California, USA
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Mishra A, Hughes AC, Amon JD, Rudner DZ, Wang X, Kearns DB. SwrA extends DegU over an UP element to activate flagellar gene expression in Bacillus subtilis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.552067. [PMID: 37577504 PMCID: PMC10418190 DOI: 10.1101/2023.08.04.552067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
SwrA activates flagellar gene expression in Bacillus subtilis to increase the frequency of motile cells in liquid and elevate flagellar density to enable swarming over solid surfaces. Here we use ChIP-seq to show that SwrA interacts with many sites on the chromosome in a manner that depends on the response regulator DegU. We identify a DegU-specific inverted repeat DNA sequence and show that SwrA synergizes with phosphorylation to increase DegU DNA binding affinity. We further show that SwrA increases the size of the DegU footprint expanding the region bound by DegU towards the promoter. The location of the DegU inverted repeat was critical and moving the binding site closer to the promoter impaired transcription more that could be explained by deactivation. We conclude that SwrA/DegU forms a heteromeric complex that enables both remote binding and interaction between the activator and RNA polymerase in the context of an interceding UP element. We speculate that multimeric activators that resolve cis-element spatial conflicts are common in bacteria and likely act on flagellar biosynthesis loci and other long operons of other multi-subunit complexes. IMPORTANCE In Bacteria, the sigma subunit of RNA polymerase recognizes specific DNA sequences called promoters that determine where gene transcription begins. Some promoters also have sequences immediately upstream called an UP element that is bound by the alpha subunit of RNA polymerase and is often necessary for transcription. Finally, promoters may be activated by transcription factors that bind DNA specific sequences and help recruit RNA polymerase to weak promoter elements. Here we show that the promoter for the 32 gene long flagellar operon in Bacillus subtilis requires an UP element and is activated by a heteromeric transcription factor of DegU and SwrA. Our evidence suggests that SwrA oligomerizes DegU over the DNA to allow RNA polymerase to interact with DegU and the UP element simultaneously. Heteromeric activator complexes are known but poorly-understood in bacteria and we speculate they may be needed to resolve spatial conflicts in the DNA sequence.
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Saleh DO, Horstmann JA, Giralt-Zúñiga M, Weber W, Kaganovitch E, Durairaj AC, Klotzsch E, Strowig T, Erhardt M. SPI-1 virulence gene expression modulates motility of Salmonella Typhimurium in a proton motive force- and adhesins-dependent manner. PLoS Pathog 2023; 19:e1011451. [PMID: 37315106 DOI: 10.1371/journal.ppat.1011451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/01/2023] [Indexed: 06/16/2023] Open
Abstract
Both the bacterial flagellum and the evolutionary related injectisome encoded on the Salmonella pathogenicity island 1 (SPI-1) play crucial roles during the infection cycle of Salmonella species. The interplay of both is highlighted by the complex cross-regulation that includes transcriptional control of the flagellar master regulatory operon flhDC by HilD, the master regulator of SPI-1 gene expression. Contrary to the HilD-dependent activation of flagellar gene expression, we report here that activation of HilD resulted in a dramatic loss of motility, which was dependent on the presence of SPI-1. Single cell analyses revealed that HilD-activation triggers a SPI-1-dependent induction of the stringent response and a substantial decrease in proton motive force (PMF), while flagellation remains unaffected. We further found that HilD activation enhances the adhesion of Salmonella to epithelial cells. A transcriptome analysis revealed a simultaneous upregulation of several adhesin systems, which, when overproduced, phenocopied the HilD-induced motility defect. We propose a model where the SPI-1-dependent depletion of the PMF and the upregulation of adhesins upon HilD-activation enable flagellated Salmonella to rapidly modulate their motility during infection, thereby enabling efficient adhesion to host cells and delivery of effector proteins.
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Affiliation(s)
- Doaa Osama Saleh
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Julia A Horstmann
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - María Giralt-Zúñiga
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Willi Weber
- Institute for Biology, Experimental Biophysics/Mechanobiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Eugen Kaganovitch
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Abilash Chakravarthy Durairaj
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Department of Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Enrico Klotzsch
- Institute for Biology, Experimental Biophysics/Mechanobiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Till Strowig
- Department of Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Marc Erhardt
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
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Cho SY, Oh HB, Yoon SI. Hexameric structure of the flagellar master regulator FlhDC from Cupriavidus necator and its interaction with flagellar promoter DNA. Biochem Biophys Res Commun 2023; 672:97-102. [PMID: 37343320 DOI: 10.1016/j.bbrc.2023.06.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 06/09/2023] [Indexed: 06/23/2023]
Abstract
Bacterial flagella are assembled with ∼30 different proteins in a defined order via diverse regulatory systems. In gram-negative bacteria from the Gammaproteobacteria and Betaproteobacteria classes, the transcription of flagellar genes is strictly controlled by the master regulator FlhDC. In Gammaproteobacteria species, the FlhDC complex has been shown to activate flagellar expression by directly interacting with the promoter region in flagellar genes. To obtain the DNA-binding mechanism of FlhDC and determine the conserved and distinct structural features of Betaproteobacteria and Gammaproteobacteria FlhDCs that are necessary for their functions, we determined the crystal structure of Betaproteobacteria Cupriavidus necator FlhDC (cnFlhDC) and biochemically analyzed its DNA-binding capacity. cnFlhDC specifically recognized the promoter DNA of the class II flagellar genes flgB and flhB. cnFlhDC adopts a ring-like heterohexameric structure (cnFlhD4C2) and harbors two Zn-Cys clusters, as observed for Gammaproteobacteria Escherichia coli FlhDC (ecFlhDC). The cnFlhDC structure exhibits positively charged surfaces across two FlhDC subunits as a putative DNA-binding site. Noticeably, the positive patch of cnFlhDC is continuous, in contrast to the separated patches of ecFlhDC. Moreover, the ternary intersection of cnFlhD4C2 behind the Zn-Cys cluster forms a unique protruding neutral structure, which is replaced with a charged cavity in the ecFlhDC structure.
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Affiliation(s)
- So Yeon Cho
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Han Byeol Oh
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Sung-Il Yoon
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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Yue Y, Wang W, Ma Y, Song N, Jia H, Li C, Wang Q, Li H, Li B. Cooperative Regulation of Flagellar Synthesis by Two EAL-Like Proteins upon Salmonella Entry into Host Cells. Microbiol Spectr 2023; 11:e0285922. [PMID: 36749049 PMCID: PMC10100727 DOI: 10.1128/spectrum.02859-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 01/12/2023] [Indexed: 02/08/2023] Open
Abstract
When Salmonella enters host cells, the synthesis of flagella is quickly turned off to escape the host immune system. In this study, we investigated the cooperative regulatory mechanism of flagellar synthesis by two EAL-like proteins, STM1344 and STM1697, in Salmonella. We found that Salmonella upregulated the expression of both STM1344 and STM1697 to various degrees upon invading host cells. Importantly, deletion of STM1697 or STM1344 led to failure of Salmonella flagellar control within host cells, suggesting that the two factors are not redundant but indispensable. STM1697 was shown to modulate Salmonella flagellar biogenesis by preventing the flagellar master protein FlhDC from recruiting RNA polymerase. However, STM1344 was identified as a bifunctional factor that inhibits RNA polymerase recruitment of FlhDC at low molar concentrations and the DNA binding activity of FlhDC at high molar concentrations. Structural analysis demonstrated that STM1344-FlhD binds more tightly than STM1697-FlhD, and size exclusion chromatography (SEC) experiments showed that STM1344 could replace STM1697 in a STM1697-FlhDC complex. Our data suggest that STM1697 might be a temporary flagellar control factor upon Salmonella entry into the host cell, while STM1344 plays a more critical role in persistent flagellar control when Salmonella organisms survive and colonize host cells for a long period of time. Our study provides a more comprehensive understanding of the complex flagellar regulatory mechanism of Salmonella based on regulation at the protein level of FlhDC. IMPORTANCE Salmonella infection kills more than 300,000 people every year. After infection, Salmonella mainly parasitizes host cells, as it prevents host cell pyroptosis by turning off the synthesis of flagellar antigen. Previous studies have determined that there are two EAL-like proteins, STM1344 and STM1697, encoded in the Salmonella genome, both of which inhibit flagellar synthesis by interacting with the flagellar master protein FlhDC. However, the expression order and simultaneous mechanism of STM1344 and STM1697 are not clear. In this study, we determined the expression profiles of the two proteins after Salmonella infection and demonstrated the cooperative mechanism of STM1344 and STM1697 interaction with FlhDC. We found that STM1344 might play a more lasting regulatory role than STM1697. Our results reveal a comprehensive flagellar control process after Salmonella entry into host cells.
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Affiliation(s)
- Yingying Yue
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Weiwei Wang
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Yue Ma
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Nannan Song
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Haihong Jia
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Cuiling Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Qi Wang
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Hui Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Bingqing Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
- Key Lab for Biotech-Drugs of National Health Commission, Jinan, Shandong, China
- Key Lab for Rare and Uncommon Diseases of Shandong Province, Jinan, Shandong, China
- Institute of Clinical Microbiology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
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12
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Calvopina-Chavez DG, Howarth RE, Memmott AK, Pech Gonzalez OH, Hafen CB, Jensen KT, Benedict AB, Altman JD, Burnside BS, Childs JS, Dallon SW, DeMarco AC, Flindt KC, Grover SA, Heninger E, Iverson CS, Johnson AK, Lopez JB, Meinzer MA, Moulder BA, Moulton RI, Russell HS, Scott TM, Shiobara Y, Taylor MD, Tippets KE, Vainerere KM, Von Wallwitz IC, Wagley M, Wiley MS, Young NJ, Griffitts JS. A large-scale genetic screen identifies genes essential for motility in Agrobacterium fabrum. PLoS One 2023; 18:e0279936. [PMID: 36598925 PMCID: PMC9812332 DOI: 10.1371/journal.pone.0279936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 12/17/2022] [Indexed: 01/05/2023] Open
Abstract
The genetic and molecular basis of flagellar motility has been investigated for several decades, with innovative research strategies propelling advances at a steady pace. Furthermore, as the phenomenon is examined in diverse bacteria, new taxon-specific regulatory and structural features are being elucidated. Motility is also a straightforward bacterial phenotype that can allow undergraduate researchers to explore the palette of molecular genetic tools available to microbiologists. This study, driven primarily by undergraduate researchers, evaluated hundreds of flagellar motility mutants in the Gram-negative plant-associated bacterium Agrobacterium fabrum. The nearly saturating screen implicates a total of 37 genes in flagellar biosynthesis, including genes of previously unknown function.
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Affiliation(s)
- Diana G. Calvopina-Chavez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Robyn E. Howarth
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Audrey K. Memmott
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Oscar H. Pech Gonzalez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Caleb B. Hafen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kyson T. Jensen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Alex B. Benedict
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jessica D. Altman
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Brittany S. Burnside
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Justin S. Childs
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Samuel W. Dallon
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Alexa C. DeMarco
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kirsten C. Flindt
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Sarah A. Grover
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Elizabeth Heninger
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Christina S. Iverson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Abigail K. Johnson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jack B. Lopez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - McKay A. Meinzer
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Brook A. Moulder
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Rebecca I. Moulton
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Hyrum S. Russell
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Tiana M. Scott
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Yuka Shiobara
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Mason D. Taylor
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kathryn E. Tippets
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kayla M. Vainerere
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Isabella C. Von Wallwitz
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Madison Wagley
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Megumi S. Wiley
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Naomi J. Young
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Joel S. Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
- * E-mail:
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13
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Tan A, Alsenani Q, Lanz M, Birchall C, Drage LKL, Picton D, Mowbray C, Ali A, Harding C, Pickard RS, Hall J, Aldridge PD. Evasion of toll-like receptor recognition by Escherichia coli is mediated via population level regulation of flagellin production. Front Microbiol 2023; 14:1093922. [PMID: 37032848 PMCID: PMC10078357 DOI: 10.3389/fmicb.2023.1093922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 03/03/2023] [Indexed: 04/11/2023] Open
Abstract
Uropathogenic Escherichia coli is a major cause of urinary tract infections. Analysis of the innate immune response in immortalized urothelial cells suggests that the bacterial flagellar subunit, flagellin, is key in inducing host defenses. A panel of 48 clinical uro-associated E. coli isolates recovered from either cystitis, pyelonephritis asymptomatic bacteriuria (ABU) or UTI-associated bacteraemia infections were characterized for motility and their ability to induce an innate response in urothelial cells stably transfected with a NF-κB luciferase reporter. Thirty-two isolates (67%) were identified as motile with strains recovered from cystitis patients exhibiting an uneven motility distribution pattern; seven of the cystitis isolates were associated with a > 5-fold increase in NF-κB signaling. To explore whether the NF-κB signaling response reflected antigenic variation, flagellin was purified from 14 different isolates. Purified flagellin filaments generated comparable NF-κB signaling responses, irrespective of either the source of the isolate or H-serotype. These data argued against any variability between isolates being related to flagellin itself. Investigations also argued that neither TLR4 dependent recognition of bacterial lipopolysaccharide nor growth fitness of the isolates played key roles in leading to the variable host response. To determine the roles, if any, of flagellar abundance in inducing these variable responses, flagellar hook numbers of a range of cystitis and ABU isolates were quantified. Images suggested that up to 60% of the isolate population exhibited flagella with the numbers averaging between 1 and 2 flagella per bacterial cell. These data suggest that selective pressures exist in the urinary tract that allow uro-associated E. coli strains to maintain motility, but exploit population heterogeneity, which together function to prevent host TLR5 recognition and bacterial killing.
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Affiliation(s)
- Aaron Tan
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Qusai Alsenani
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Marcello Lanz
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Christopher Birchall
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Lauren K. L. Drage
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David Picton
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Catherine Mowbray
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ased Ali
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Christopher Harding
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- Urology Department, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Robert S. Pickard
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- Urology Department, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Judith Hall
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- *Correspondence: Judith Hall,
| | - Phillip D. Aldridge
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- Phillip D. Aldridge,
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14
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Hwang YJ, Jo J, Kim E, Yoon H, Hong H, Kim MS, Myung H. Motility increase of adherent invasive Escherichia coli (AIEC) induced by a sub-inhibitory concentration of recombinant endolysin LysPA90. Front Microbiol 2022; 13:1093670. [PMID: 36619993 PMCID: PMC9814724 DOI: 10.3389/fmicb.2022.1093670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Endolysins are bacteriophage enzymes required for the eruption of phages from inside host bacteria via the degradation of the peptidoglycan cell wall. Recombinant endolysins are increasingly being seen as potential antibacterial candidates, with a number currently undergoing clinical trials. Bacteriophage PBPA90 infecting Pseudomonas aeruginosa harbors a gene encoding an endolysin, lysPA90. Herein, recombinant LysPA90 demonstrated an intrinsic antibacterial activity against Escherichia coli in vitro. It was observed that a sub-inhibitory concentration of the recombinant protein induced the upregulation of genes related to flagella biosynthesis in a commensal E. coli strain. Increases in the number of bacterial flagella, and in motility, were experimentally substantiated. The treatment caused membrane stress, leading to the upregulation of genes rpoE, rpoH, dnaK, dnaJ, and flhC, which are upstream regulators of flagella biosynthesis. When adherent invasive Escherichia coli (AIEC) strains were treated with subinhibitory concentrations of the endolysin, bacterial adhesion and invasion into intestinal epithelial Caco-2 cells was seen to visibly increase under microscopic examination. Bacterial counting further corroborated this adhesion and invasion of AIEC strains into Caco-2 cells, with a resultant slight decrease in the viability of Caco-2 cells then being observed. Additionally, genes related to flagella expression were also upregulated in the AIEC strains. Finally, the enhanced expression of the proinflammatory cytokine genes TNF-α, IL-6, IL-8, and MCP1 in Caco-2 cells was noted after the increased invasion of the AIEC strains. While novel treatments involving endolysins offer great promise, these results highlight the need for the further exploration of possible unanticipated and unintended effects.
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Affiliation(s)
- Yoon Jung Hwang
- Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yong-In, Gyung-Gi Do, South Korea
- LyseNTech Co. Ltd., Seongnam, Gyung-Gi Do, South Korea
| | - Jaehak Jo
- Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yong-In, Gyung-Gi Do, South Korea
| | - Eunsuk Kim
- Department of Molecular Science and Technology, Ajou University, Suwon, Gyung-Gi Do, South Korea
| | - Hyunjin Yoon
- Department of Molecular Science and Technology, Ajou University, Suwon, Gyung-Gi Do, South Korea
| | - Hyewon Hong
- LyseNTech Co. Ltd., Seongnam, Gyung-Gi Do, South Korea
| | - Min Soo Kim
- LyseNTech Co. Ltd., Seongnam, Gyung-Gi Do, South Korea
| | - Heejoon Myung
- Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yong-In, Gyung-Gi Do, South Korea
- LyseNTech Co. Ltd., Seongnam, Gyung-Gi Do, South Korea
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15
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Yao R, Mao X, Xu Y, Qiu X, Zhou L, Wang Y, Pang B, Chen M, Cao S, Bao L, Bao Y, Guo S, Hu L, Zhang H, Cui X. Polysaccharides from Vaccaria segetalis seeds reduce urinary tract infections by inhibiting the adhesion and invasion abilities of uropathogenic Escherichia coli. Front Cell Infect Microbiol 2022; 12:1004751. [PMID: 36506014 PMCID: PMC9727262 DOI: 10.3389/fcimb.2022.1004751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/01/2022] [Indexed: 11/24/2022] Open
Abstract
The seeds of Vaccaria segetalis (Neck.) are from a traditional medicinal plant Garcke, also called Wang-Bu-Liu-Xing in China. According to the Chinese Pharmacopoeia, the seeds of V. segetalis can be used for treating urinary system diseases. This study was designed to investigate the underlying mechanism of VSP (polysaccharides from Vaccaria segetalis) against urinary tract infections caused by uropathogenic Escherichia coli (UPEC). Here, both in vitro and in vivo infection models were established with the UPEC strain CFT073. Bacterial adhesion and invasion into bladder epithelial cells were analyzed. We found that VSP reduced the adhesion of UPEC to the host by inhibiting the expression of bacterial hair follicle adhesion genes. VSP also reduced the invasion of UPEC by regulating the uroplakins and Toll-like receptors of host epithelial cells. In addition, the swarming motility and flagella-mediated motility genes flhC, flhD and Flic of UPEC were diminished after VSP intervention. Taken together, our findings reveal a possible mechanism by which VSP interferes with the adhesion and invasion of UPEC.
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Affiliation(s)
- Rongmei Yao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China,Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Xin Mao
- Guangzhou Baiyunshan Xingqun Pharmaceutical Co., Ltd, Guangzhou, China
| | - Yingli Xu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xue Qiu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Lirun Zhou
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yaxin Wang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Bo Pang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Mengping Chen
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Shan Cao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Lei Bao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yanyan Bao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Shanshan Guo
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Limin Hu
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Haijiang Zhang
- Jiangsu Key Laboratory of Regional Resource Exploitation and Medicinal Research, Huaiyin Institute of Technology, Huai’an, China,*Correspondence: Haijiang Zhang, ; Xiaolan Cui,
| | - Xiaolan Cui
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China,*Correspondence: Haijiang Zhang, ; Xiaolan Cui,
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16
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Yuan X, Eldred LI, Sundin GW. Exopolysaccharides amylovoran and levan contribute to sliding motility in the fire blight pathogen Erwinia amylovora. Environ Microbiol 2022; 24:4738-4754. [PMID: 36054324 PMCID: PMC9826367 DOI: 10.1111/1462-2920.16193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/31/2022] [Indexed: 01/11/2023]
Abstract
Erwinia amylovora, the causative agent of fire blight, uses flagella-based motilities to translocate to host plant natural openings; however, little is known about how this bacterium migrates systemically in the apoplast. Here, we reveal a novel surface motility mechanism, defined as sliding, in E. amylovora. Deletion of flagella assembly genes did not affect this movement, whereas deletion of biosynthesis genes for the exopolysaccharides (EPSs) amylovoran and levan resulted in non-sliding phenotypes. Since EPS production generates osmotic pressure that potentially powers sliding, we validated this mechanism by demonstrating that water potential positively contributes to sliding. In addition, no sliding was observed when the water potential of the surface was lower than -0.5 MPa. Sliding is a passive motility mechanism. We further show that the force of gravity plays a critical role in directing E. amylovora sliding on unconfined surfaces but has a negligible effect when cells are sliding in confined microcapillaries, in which EPS-dependent osmotic pressure acts as the main force. Although amylovoran and levan are both required for sliding, we demonstrate that they exhibit different roles in bacterial communities. In summary, our study provides fundamental knowledge for a better understanding of mechanisms that drive bacterial sliding motility.
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Affiliation(s)
- Xiaochen Yuan
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast LansingMichiganUSA
| | - Lauren I. Eldred
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast LansingMichiganUSA
| | - George W. Sundin
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast LansingMichiganUSA
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17
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Regulatory Interplay between RNase III and Antisense RNAs in E. coli: the Case of AsflhD and FlhD, Component of the Master Regulator of Motility. mBio 2022; 13:e0098122. [PMID: 36000733 PMCID: PMC9600491 DOI: 10.1128/mbio.00981-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to respond to ever-changing environmental cues, bacteria display resilient regulatory mechanisms controlling gene expression. At the post-transcriptional level, this is achieved by a combination of RNA-binding proteins, such as ribonucleases (RNases), and regulatory RNAs, including antisense RNAs (asRNAs). Bound to their complementary mRNA, asRNAs are primary targets for the double-strand-specific endoribonuclease, RNase III. Taking advantage of our own and previously published transcriptomic data sets obtained in strains inactivated for RNase III, we selected several candidate asRNAs and confirmed the existence of RNase III-sensitive asRNAs for crp, ompR, phoP, and flhD genes, all encoding global regulators of gene expression in Escherichia coli. Using FlhD, a component of the master regulator of motility (FlhD4C2), as our model, we demonstrate that the asRNA AsflhD, transcribed from the coding sequence of flhD, is involved in the fine-tuning of flhD expression and thus participates in the control of motility.
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18
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Qu D, Jiang M, Duffin C, Hughes KT, Chevance FFV. Targeting early proximal-rod component substrate FlgB to FlhB for flagellar-type III secretion in Salmonella. PLoS Genet 2022; 18:e1010313. [PMID: 35819991 PMCID: PMC9307174 DOI: 10.1371/journal.pgen.1010313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/22/2022] [Accepted: 06/24/2022] [Indexed: 11/18/2022] Open
Abstract
The Salmonella flagellar secretion apparatus is a member of the type III secretion (T3S) family of export systems in bacteria. After completion of the flagellar motor structure, the hook-basal body (HBB), the flagellar T3S system undergoes a switch from early to late substrate secretion, which results in the expression and assembly of the external, filament propeller-like structure. In order to characterize early substrate secretion-signals in the flagellar T3S system, the FlgB, and FlgC components of the flagellar rod, which acts as the drive-shaft within the HBB, were subject to deletion mutagenesis to identify regions of these proteins that were important for secretion. The β-lactamase protein lacking its Sec-dependent secretion signal (Bla) was fused to the C-terminus of FlgB and FlgC and used as a reporter to select for and quantify the secretion of FlgB and FlgC into the periplasm. Secretion of Bla into the periplasm confers resistance to ampicillin. In-frame deletions of amino acids 9 through 18 and amino acids 39 through 58 of FlgB decreased FlgB secretion levels while deleting amino acid 6 through 14 diminished FlgC secretion levels. Further PCR-directed mutagenesis indicated that amino acid F45 of FlgB was critical for secretion. Single amino acid mutagenesis revealed that all amino acid substitutions at F45 of FlgB position impaired rod assembly, which was due to a defect of FlgB secretion. An equivalent F49 position in FlgC was essential for assembly but not for secretion. This study also revealed that a hydrophobic patch in the cleaved C-terminal domain of FlhB is critical for recognition of FlgB at F45. Type III secretion (T3S) is the means by which proteins are secreted from the bacterial cytoplasm to build flagella for motility and injectisome structures that facilitate pathogenesis. T3S is the only secretion system known to date that undergoes a secretion-specificity switch. For the assembly of the bacterial flagellum, the T3S system initially secretes early substrates to build the hook-basal body (HBB), which is the main component that makes up the flagellar motor. Upon HBB completion, the flagellar T3S system becomes specific for late substrates, which make up the long external filament that acts as the propeller of the motility organelle. This work identifies important sites of interaction between an early substrate, FlgB and a target site at the cytoplasmic base of T3S apparatus. A second early substrate, FlgC, lacks the targeting interaction found for FlgB suggesting a mechanism that distinguishes early substrates, and may indicate an order to early substrate secretion to facilitate the order of protein subunit assembly for the flagellum.
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Affiliation(s)
- Daofeng Qu
- Key Laboratory of Food Quality and Safety, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Mengxue Jiang
- Key Laboratory of Food Quality and Safety, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Calder Duffin
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Kelly T. Hughes
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Fabienne F. V. Chevance
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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19
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Switching off Bacterial Flagellar Biogenesis by YdiU-Mediated UMPylation of FlhDC. mBio 2022; 13:e0024922. [PMID: 35532215 PMCID: PMC9239255 DOI: 10.1128/mbio.00249-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bacterial flagellin activates the host immune system and triggers pyroptosis. Salmonella reduces flagellin expression when it survives within host cells. Here, we found that the UMPylator YdiU significantly altered the Salmonella flagellar biogenesis process upon host cell entry. The expression levels of class II and class III flagellar genes, but not the class I flagellar genes flhDC, were dramatically increased in a ΔydiU strain compared to wild-type (WT) Salmonella in a host-simulating environment. A direct interaction between YdiU and FlhDC was detected by bacterial two-hybrid assay. Furthermore, YdiU efficiently catalyzed the UMPylation of FlhC but not FlhD, FliA, or FliC. UMPylation of FlhC completely eliminated its DNA-binding activity. In vivo experiments showed that YdiU was required and sufficient for Salmonella flagellar control within host cells. Mice infected with the ΔydiU strain died much earlier than WT strain-infected mice and developed much more severe inflammation and injury in organs and much higher levels of cytokines in blood, demonstrating that early host death induced by the ΔydiU strain is probably due to excessive inflammation. Our results indicate that YdiU acts as an essential factor of Salmonella to mediate host immune escape.
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20
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Riborg A, Colquhoun DJ, Gulla S. Biotyping reveals loss of motility in two distinct Yersinia ruckeri lineages exclusive to Norwegian aquaculture. JOURNAL OF FISH DISEASES 2022; 45:641-653. [PMID: 35180320 PMCID: PMC9304254 DOI: 10.1111/jfd.13590] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 05/26/2023]
Abstract
Non-motile strains of Yersinia ruckeri, known as Y. ruckeri biotype 2, now dominate amongst clinical isolates retrieved from rainbow trout internationally. Due to an acute increase in the number of yersiniosis cases in Norway in recent years, followed by introduction of widespread intraperitoneal vaccination against the disease, an investigation on the prevalence of Y. ruckeri biotype 2 in Norwegian aquaculture was conducted. We biotyped 263 Y. ruckeri isolates recovered from diseased salmonids in Norway between 1985 and 2020. A total of seven biotype 2 isolates were identified, four of which were collected between 1985 and 1987, and three of which belong to the current epizootic clone, isolated from two different sea-farms in 2017. Whole-genome sequencing revealed single non-synonymous nucleotide polymorphisms in the flagellar genes flhC in isolates from the 1980s, and in fliP in isolates from 2017. In both variants, motility was restored both by complementation with wild-type alleles in trans and via spontaneous mutation-driven reversion following prolonged incubation on motility agar. While biotype 2 strains do not yet seem to have become broadly established in Norwegian aquaculture, the seven isolates described here serve to document a further two independent cases of Y. ruckeri biotype 2 emergence in salmonid aquaculture.
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Affiliation(s)
- Andreas Riborg
- Norwegian Veterinary InstituteÅsNorway
- Vaxxinova Norway ASBergenNorway
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21
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Identification of Key Factors for Anoxic Survival of B. cenocepacia H111. Int J Mol Sci 2022; 23:ijms23094560. [PMID: 35562951 PMCID: PMC9104464 DOI: 10.3390/ijms23094560] [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: 03/07/2022] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 11/21/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen that can lead to severe infections in patients suffering from cystic fibrosis (CF) and chronic granulomatous disease. Being an obligate aerobe, B. cenocepacia is unable to grow in the absence of oxygen. In this study, we show that the CF isolate B. cenocepacia H111 can survive in the absence of oxygen. Using a transposon sequencing (Tn-seq) approach, we identified 71 fitness determinants involved in anoxic survival, including a Crp-Fnr family transcriptional regulatory gene (anr2), genes coding for the sensor kinase RoxS and its response regulator RoxR, the sigma factor for flagella biosynthesis (FliA) and subunits of a cytochrome bd oxidase (CydA, CydB and the potentially novel subunit CydP). Individual knockouts of these fitness determinants significantly reduced anoxic survival, and inactivation of both anr copies is shown to be lethal under anoxic conditions. We also show that the two-component system RoxS/RoxR and FliA are important for virulence and swarming/swimming, respectively.
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22
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Hu J, Lv X, Niu X, Yu F, Zuo J, Bao Y, Yin H, Huang C, Nawaz S, Zhou W, Jiang W, Chen Z, Tu J, Qi K, Han X. Effect of nutritional and environmental conditions on biofilm formation of avian pathogenic Escherichia coli. J Appl Microbiol 2022; 132:4236-4251. [PMID: 35343028 DOI: 10.1111/jam.15543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/19/2022] [Accepted: 03/21/2022] [Indexed: 11/30/2022]
Abstract
AIMS To study the effects of environmental stress and nutrient conditions on biofilm formation of avian pathogenic Escherichia coli (APEC). METHODS AND RESULTS The APEC strain DE17 was used to study biofilm formation under various conditions of environmental stress (including different temperatures, pH, metal ions, and antibiotics) and nutrient conditions (LB and M9 media, with the addition of different carbohydrates, if necessary). The DE17 biofilm formation ability was strongest at 25°C in LB medium. Compared to incubation at 37°C, three biofilm-related genes (csgD, dgcC, and pfs) were significantly upregulated and two genes (flhC and flhD) were downregulated at 25°C, which resulted in decreased motility. However, biofilm formation was strongest in M9 medium supplemented with glucose at 37°C, and the number of live bacteria was the highest as determined by confocal laser scanning microscopy (CLSM). The bacteria in the biofilm were surrounded by a thick extracellular matrix, and honeycomb-like or rough surfaces were observed by scanning electron microscopy (SEM). Moreover, biofilm formation of the DE17 strain was remarkably inhibited under acidic conditions, whereas neutral and alkaline conditions were more suitable for biofilm formation. Biofilm formation was also inhibited at specific concentrations of cations (Na+ , K+ , Ca2+ , and Mg2+ ) and antibiotics (ampicillin, chloramphenicol, kanamycin, and spectinomycin). The qRT-PCR showed that the transcription levels of biofilm-related genes change under different environmental conditions. CONCLUSIONS Nutritional and environmental factors played an important role in DE17 biofilm development. The transcription levels of biofilm-related genes changed under different environmental and nutrient conditions. SIGNIFICANCE AND IMPACT OF THE STUDY The findings suggest that nutritional and environmental factors play an important role in APEC biofilm development. Depending on the different conditions involved in this study, it can serve as a guide to treating biofilm-related infections and to eliminating biofilms from the environment.
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Affiliation(s)
- Jiangang Hu
- Engineering Research Center for the Prevention and Control of Animal Original Zoonosis, Fujian Province, College of Life Science, Longyan University, Longyan, Fujian, China.,Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China.,Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui, China
| | - Xiaolong Lv
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China.,Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui, China
| | - Xiangpeng Niu
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China.,Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui, China
| | - Fangheng Yu
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China.,Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui, China
| | - Jiakun Zuo
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China
| | - Yinli Bao
- Engineering Research Center for the Prevention and Control of Animal Original Zoonosis, Fujian Province, College of Life Science, Longyan University, Longyan, Fujian, China
| | - Huifang Yin
- Engineering Research Center for the Prevention and Control of Animal Original Zoonosis, Fujian Province, College of Life Science, Longyan University, Longyan, Fujian, China
| | - Cuiqin Huang
- Engineering Research Center for the Prevention and Control of Animal Original Zoonosis, Fujian Province, College of Life Science, Longyan University, Longyan, Fujian, China
| | - Saqib Nawaz
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China
| | - Wen Zhou
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China
| | - Wei Jiang
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China
| | - Zhaoguo Chen
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China
| | - Jian Tu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui, China
| | - Kezong Qi
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui, China
| | - Xiangan Han
- Engineering Research Center for the Prevention and Control of Animal Original Zoonosis, Fujian Province, College of Life Science, Longyan University, Longyan, Fujian, China.,Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, China
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23
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Seco EM, Fernández LÁ. Efficient markerless integration of genes in the chromosome of probiotic E. coli Nissle 1917 by bacterial conjugation. Microb Biotechnol 2021; 15:1374-1391. [PMID: 34755474 PMCID: PMC9049610 DOI: 10.1111/1751-7915.13967] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 10/22/2021] [Accepted: 10/23/2021] [Indexed: 01/30/2023] Open
Abstract
The probiotic strain Escherichia coli Nissle 1917 (EcN) is a common bacterial chassis in synthetic biology developments for therapeutic applications given its long track record of safe administration in humans. Chromosomal integration of the genes of interest (GOIs) in the engineered bacterium offers significant advantages in genetic stability and to control gene dose, but common methodologies relying on the transformation of EcN are inefficient. In this work, we implement in EcN the use of bacterial conjugation in combination with markerless genome engineering to efficiently insert multiple GOIs at different loci of EcN chromosome, leaving no antibiotic resistance genes, vector sequences or scars in the modified bacterium. The resolution of cointegrants that leads to markerless insertion of the GOIs requires expression of I-SceI endonuclease and its efficiency is enhanced by λ Red proteins. We show the potential of this strategy by integrating different genes encoding fluorescent and bioluminescent reporters (i.e. GFP, mKate2, luxCDABE) both individually and sequentially. We also demonstrate its application for gene deletions in EcN (ΔflhDC) and to replace the endogenous regulation of chromosomal locus (i.e. flhDC) by heterologous regulatory elements (e.g. tetR-Ptet) in order to have an ectopic control of gene expression in EcN with an external inducer to alter bacterial behaviour (e.g. flagellar motility). Whole-genome sequencing confirmed the introduction of the designed modifications without off-target alterations in the genome. This straightforward approach accelerates the generation of multiple modifications in EcN chromosome for the generation of living bacterial therapeutics.
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Affiliation(s)
- Elena M Seco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, Campus UAM Cantoblanco, Madrid, 28049, Spain
| | - Luis Ángel Fernández
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, Campus UAM Cantoblanco, Madrid, 28049, Spain
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24
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Multiple Copies of flhDC in Paraburkholderia unamae Regulate Flagellar Gene Expression, Motility, and Biofilm Formation. J Bacteriol 2021; 203:e0029321. [PMID: 34543106 DOI: 10.1128/jb.00293-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
FlhDC is a heterohexameric complex that acts as a master regulator of flagellar biosynthesis genes in numerous bacteria. Previous studies have identified a single flhDC operon encoding this complex. However, we found that two flhDC loci are present throughout Paraburkholderia, and two additional flhC copies are also present in Paraburkholderia unamae. Systematic deletion analysis in P. unamae of the different flhDC copies showed that one of the operons, flhDC1, plays the predominant role, with deletion of its genes resulting in a severe inhibition of motility and biofilm formation. Expression analysis using promoter-lacZ fusions and real-time quantitative PCR support the primary role of flhDC1 in flagellar gene regulation, with flhDC2 a secondary contributor. Phylogenetic analysis shows the presence of the flhDC1 and flhDC2 operons throughout Paraburkholderia. In contrast, Burkholderia and other bacteria only carry the copy syntenous with flhDC2. The variations in impact each copy of flhDC has on downstream processes indicate that regulation of FlhDC in P. unamae, and likely other Paraburkholderia species, is regulated at least in part by the presence of multiple copies of these genes. IMPORTANCE Motility is important in the colonization of plant roots by beneficial and pathogenic bacteria, with flagella playing essential roles in host cell adhesion, entrance, and biofilm formation. Flagellar biosynthesis is energetically expensive. Its complex regulation by the FlhDC master regulator is well studied in peritrichous flagella expressing enterics. We report the unique presence throughout Paraburkholderia of multiple copies of flhDC. In P. unamae, the flhDC1 copy showed higher expression and a greater effect on swim motility, flagellar development, and regulation of downstream genes, than the flhDC2 copy that is syntenous to flhDC in Escherichia coli and pathogenic Burkholderia spp. The flhDC genes have evolved differently in these plant-growth-promoting bacteria, giving an additional layer of complexity in gene regulation by FlhDC.
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25
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Raman V, Van Dessel N, Hall CL, Wetherby VE, Whitney SA, Kolewe EL, Bloom SMK, Sharma A, Hardy JA, Bollen M, Van Eynde A, Forbes NS. Intracellular delivery of protein drugs with an autonomously lysing bacterial system reduces tumor growth and metastases. Nat Commun 2021; 12:6116. [PMID: 34675204 PMCID: PMC8531320 DOI: 10.1038/s41467-021-26367-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/01/2021] [Indexed: 12/25/2022] Open
Abstract
Critical cancer pathways often cannot be targeted because of limited efficiency crossing cell membranes. Here we report the development of a Salmonella-based intracellular delivery system to address this challenge. We engineer genetic circuits that (1) activate the regulator flhDC to drive invasion and (2) induce lysis to release proteins into tumor cells. Released protein drugs diffuse from Salmonella containing vacuoles into the cellular cytoplasm where they interact with their therapeutic targets. Control of invasion with flhDC increases delivery over 500 times. The autonomous triggering of lysis after invasion makes the platform self-limiting and prevents drug release in healthy organs. Bacterial delivery of constitutively active caspase-3 blocks the growth of hepatocellular carcinoma and lung metastases, and increases survival in mice. This success in targeted killing of cancer cells provides critical evidence that this approach will be applicable to a wide range of protein drugs for the treatment of solid tumors.
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Affiliation(s)
- Vishnu Raman
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
- Ernest Pharmaceuticals, LLC, Hadley, MA, USA
| | - Nele Van Dessel
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
- Ernest Pharmaceuticals, LLC, Hadley, MA, USA
| | - Christopher L Hall
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
- Ernest Pharmaceuticals, LLC, Hadley, MA, USA
| | | | - Samantha A Whitney
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
| | - Emily L Kolewe
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
| | - Shoshana M K Bloom
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
| | - Abhinav Sharma
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA
| | - Jeanne A Hardy
- Department of Chemistry, University of Massachusetts, Amherst, Amherst, MA, USA
- Molecular and Cell Biology Program, University of Massachusetts, Amherst, Amherst, MA, USA
- Institute for Applied Life Science, University of Massachusetts, Amherst, Amherst, MA, USA
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Neil S Forbes
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, MA, USA.
- Ernest Pharmaceuticals, LLC, Hadley, MA, USA.
- Molecular and Cell Biology Program, University of Massachusetts, Amherst, Amherst, MA, USA.
- Institute for Applied Life Science, University of Massachusetts, Amherst, Amherst, MA, USA.
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26
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Durand R, Huguet KT, Rivard N, Carraro N, Rodrigue S, Burrus V. Crucial role of Salmonella genomic island 1 master activator in the parasitism of IncC plasmids. Nucleic Acids Res 2021; 49:7807-7824. [PMID: 33834206 PMCID: PMC8373056 DOI: 10.1093/nar/gkab204] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 03/09/2021] [Accepted: 03/15/2021] [Indexed: 12/26/2022] Open
Abstract
IncC conjugative plasmids and the multiple variants of Salmonella Genomic Island 1 (SGI1) are two functionally interacting families of mobile genetic elements commonly associated with multidrug resistance in the Gammaproteobacteria. SGI1 and its siblings are specifically mobilised in trans by IncC conjugative plasmids. Conjugative transfer of IncC plasmids is activated by the plasmid-encoded master activator AcaCD. SGI1 carries five AcaCD-responsive promoters that drive the expression of genes involved in its excision, replication, and mobilisation. SGI1 encodes an AcaCD homologue, the transcriptional activator complex SgaCD (also known as FlhDCSGI1) that seems to recognise and activate the same SGI1 promoters. Here, we investigated the relevance of SgaCD in SGI1's lifecycle. Mating assays revealed the requirement for SgaCD and its IncC-encoded counterpart AcaCD in the mobilisation of SGI1. An integrative approach combining ChIP-exo, Cappable-seq, and RNA-seq confirmed that SgaCD activates each of the 18 AcaCD-responsive promoters driving the expression of the plasmid transfer functions. A comprehensive analysis of the activity of the complete set of AcaCD-responsive promoters of SGI1 and the helper IncC plasmid was performed through reporter assays. qPCR and flow cytometry assays revealed that SgaCD is essential to elicit the excision and replication of SGI1 and destabilise the helper IncC plasmid.
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Affiliation(s)
- Romain Durand
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Kévin T Huguet
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Nicolas Rivard
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Nicolas Carraro
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Sébastien Rodrigue
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Vincent Burrus
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
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27
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Medina Munoz M, Brenner C, Richmond D, Spencer N, Rio RVM. The holobiont transcriptome of teneral tsetse fly species of varying vector competence. BMC Genomics 2021; 22:400. [PMID: 34058984 PMCID: PMC8166097 DOI: 10.1186/s12864-021-07729-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 05/21/2021] [Indexed: 12/13/2022] Open
Abstract
Background Tsetse flies are the obligate vectors of African trypanosomes, which cause Human and Animal African Trypanosomiasis. Teneral flies (newly eclosed adults) are especially susceptible to parasite establishment and development, yet our understanding of why remains fragmentary. The tsetse gut microbiome is dominated by two Gammaproteobacteria, an essential and ancient mutualist Wigglesworthia glossinidia and a commensal Sodalis glossinidius. Here, we characterize and compare the metatranscriptome of teneral Glossina morsitans to that of G. brevipalpis and describe unique immunological, physiological, and metabolic landscapes that may impact vector competence differences between these two species. Results An active expression profile was observed for Wigglesworthia immediately following host adult metamorphosis. Specifically, ‘translation, ribosomal structure and biogenesis’ followed by ‘coenzyme transport and metabolism’ were the most enriched clusters of orthologous genes (COGs), highlighting the importance of nutrient transport and metabolism even following host species diversification. Despite the significantly smaller Wigglesworthia genome more differentially expressed genes (DEGs) were identified between interspecific isolates (n = 326, ~ 55% of protein coding genes) than between the corresponding Sodalis isolates (n = 235, ~ 5% of protein coding genes) likely reflecting distinctions in host co-evolution and adaptation. DEGs between Sodalis isolates included genes involved in chitin degradation that may contribute towards trypanosome susceptibility by compromising the immunological protection provided by the peritrophic matrix. Lastly, G. brevipalpis tenerals demonstrate a more immunologically robust background with significant upregulation of IMD and melanization pathways. Conclusions These transcriptomic differences may collectively contribute to vector competence differences between tsetse species and offers translational relevance towards the design of novel vector control strategies. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07729-5.
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Affiliation(s)
- Miguel Medina Munoz
- Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, WV, 26505, USA
| | - Caitlyn Brenner
- Department of Biology, Washington and Jefferson College, Washington, PA, 15301, USA
| | - Dylan Richmond
- Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, WV, 26505, USA
| | - Noah Spencer
- Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, WV, 26505, USA
| | - Rita V M Rio
- Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, WV, 26505, USA.
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28
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Huang WC, Hashimoto M, Shih YL, Wu CC, Lee MF, Chen YL, Wu JJ, Wang MC, Lin WH, Hong MY, Teng CH. Peptidoglycan Endopeptidase Spr of Uropathogenic Escherichia coli Contributes to Kidney Infections and Competitive Fitness During Bladder Colonization. Front Microbiol 2021; 11:586214. [PMID: 33391204 PMCID: PMC7774453 DOI: 10.3389/fmicb.2020.586214] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/25/2020] [Indexed: 11/27/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) is the most common pathogen of urinary tract infections (UTIs). Antibiotic therapy is the conventional measure to manage such infections. However, the rapid emergence of antibiotic resistance has reduced the efficacy of antibiotic treatment. Given that the bacterial factors required for the full virulence of the pathogens are potential therapeutic targets, identifying such factors may facilitate the development of novel therapeutic strategies against UPEC UTIs. The peptidoglycan (PG) endopeptidase Spr (also named MepS) is required for PG biogenesis in E. coli. In the present study, we found that Spr deficiency attenuated the ability of UPEC to infect kidneys and induced a fitness defect during bladder colonization in a mouse model of UTI. Based on the liquid chromatography (LC)/mass spectrometry (MS)/MS analysis of the bacterial envelope, spr deletion changed the levels of some envelope-associated proteins, suggesting that Spr deficiency interfere with the components of the bacterial structure. Among the proteins, FliC was significantly downregulated in the spr mutant, which is resulted in reduced motility. Lack of Spr might hinder the function of the flagellar transcriptional factor FlhDC to decrease FliC expression. The motility downregulation contributed to the reduced fitness in urinary tract colonization. Additionally, spr deletion compromised the ability of UPEC to evade complement-mediated attack and to resist intracellular killing of phagocytes, consequently decreasing UPEC bloodstream survival. Spr deficiency also interfered with the UPEC morphological switch from bacillary to filamentous shapes during UTI. It is known that bacterial filamentation protects UPEC from phagocytosis by phagocytes. In conclusion, Spr deficiency was shown to compromise multiple virulence properties of UPEC, leading to attenuation of the pathogen in urinary tract colonization and bloodstream survival. These findings indicate that Spr is a potential antimicrobial target for further studies attempting to develop novel strategies in managing UPEC UTIs.
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Affiliation(s)
- Wen-Chun Huang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Masayuki Hashimoto
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Ling Shih
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chia-Ching Wu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Mei-Feng Lee
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
| | - Ya-Lei Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
| | - Jiunn-Jong Wu
- Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang Ming University, Taipei, Taiwan
| | - Ming-Cheng Wang
- Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Hung Lin
- Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ming-Yuan Hong
- Department of Emergency Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Hao Teng
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
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29
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Yuan X, Yu M, Yang CH. Innovation and Application of the Type III Secretion System Inhibitors in Plant Pathogenic Bacteria. Microorganisms 2020; 8:microorganisms8121956. [PMID: 33317075 PMCID: PMC7764658 DOI: 10.3390/microorganisms8121956] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/05/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022] Open
Abstract
Many Gram-negative pathogenic bacteria rely on a functional type III secretion system (T3SS), which injects multiple effector proteins into eukaryotic host cells, for their pathogenicity. Genetic studies conducted in different host-microbe pathosystems often revealed a sophisticated regulatory mechanism of their T3SSs, suggesting that the expression of T3SS is tightly controlled and constantly monitored by bacteria in response to the ever-changing host environment. Therefore, it is critical to understand the regulation of T3SS in pathogenic bacteria for successful disease management. This review focuses on a model plant pathogen, Dickeyadadantii, and summarizes the current knowledge of its T3SS regulation. We highlight the roles of several T3SS regulators that were recently discovered, including the transcriptional regulators: FlhDC, RpoS, and SlyA; the post-transcriptional regulators: PNPase, Hfq with its dependent sRNA ArcZ, and the RsmA/B system; and the bacterial second messenger cyclic-di-GMP (c-di-GMP). Homologs of these regulatory components have also been characterized in almost all major bacterial plant pathogens like Erwiniaamylovora, Pseudomonassyringae, Pectobacterium spp., Xanthomonas spp., and Ralstonia spp. The second half of this review shifts focus to an in-depth discussion of the innovation and development of T3SS inhibitors, small molecules that inhibit T3SSs, in the field of plant pathology. This includes T3SS inhibitors that are derived from plant phenolic compounds, plant coumarins, and salicylidene acylhydrazides. We also discuss their modes of action in bacteria and application for controlling plant diseases.
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Affiliation(s)
- Xiaochen Yuan
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA;
| | - Manda Yu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- Correspondence: (M.Y.); (C.-H.Y.)
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- Correspondence: (M.Y.); (C.-H.Y.)
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Wang L, Wu Y, Cai P, Huang Q. The attachment process and physiological properties of Escherichia coli O157:H7 on quartz. BMC Microbiol 2020; 20:355. [PMID: 33213384 PMCID: PMC7677791 DOI: 10.1186/s12866-020-02043-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/09/2020] [Indexed: 01/24/2023] Open
Abstract
Background Manure application and sewage irrigation release many intestinal pathogens into the soil. After being introduced into the soil matrix, pathogens are commonly found to attach to soil minerals. Although the survival of mineral-associated Escherichia coli O157:H7 has been studied, a comprehensive understanding of the attachment process and physiological properties after attachment is still lacking. Results In this study, planktonic and attached Escherichia coli O157:H7 cells on quartz were investigated using RNA sequencing (RNA-seq) and the isobaric tagging for relative and absolute quantitation (iTRAQ) proteomic method. Based on the transcriptomic and proteomic analyses and gene knockouts, functional two-component system pathways were required for efficient attachment; chemotaxis and the Rcs system were identified to play determinant roles in E. coli O157:H7 attachment on quartz. After attachment, the pyruvate catabolic pathway shifted from the tricarboxylic acid (TCA) cycle toward the fermentative route. The survival rate of attached E. coli O157:H7 increased more than 10-fold under penicillin and vancomycin stress and doubled under alkaline pH and ferric iron stress. Conclusions These results contribute to the understanding of the roles of chemotaxis and the Rcs system in the attachment process of pathogens and indicate that the attachment of pathogens to minerals significantly elevates their resistance to antibiotics and environmental stress, which may pose a potential threat to public health. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-020-02043-8.
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Affiliation(s)
- Liliang Wang
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yichao Wu
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Peng Cai
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
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Utsey K, Keener JP. A mathematical model of flagellar gene regulation and construction in Salmonella enterica. PLoS Comput Biol 2020; 16:e1007689. [PMID: 33090999 PMCID: PMC7608950 DOI: 10.1371/journal.pcbi.1007689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 11/03/2020] [Accepted: 08/16/2020] [Indexed: 11/19/2022] Open
Abstract
Millions of people worldwide develop foodborne illnesses caused by Salmonella enterica (S. enterica) every year. The pathogenesis of S. enterica depends on flagella, which are appendages that the bacteria use to move through the environment. Interestingly, populations of genetically identical bacteria exhibit heterogeneity in the number of flagella. To understand this heterogeneity and the regulation of flagella quantity, we propose a mathematical model that connects the flagellar gene regulatory network to flagellar construction. A regulatory network involving more than 60 genes controls flagellar assembly. The most important member of the network is the master operon, flhDC, which encodes the FlhD4C2 protein. FlhD4C2 controls the construction of flagella by initiating the production of hook basal bodies (HBBs), protein structures that anchor the flagella to the bacterium. By connecting a model of FlhD4C2 regulation to a model of HBB construction, we investigate the roles of various feedback mechanisms. Analysis of our model suggests that a combination of regulatory mechanisms at the protein and transcriptional levels induce bistable FlhD4C2 levels and heterogeneous numbers of flagella. Also, the balance of regulatory mechanisms that become active following HBB construction is sufficient to provide a counting mechanism for controlling the total number of flagella produced. Salmonella causes foodborne illnesses in millions of people worldwide each year. Flagella, which are appendages that the bacteria use to move through the environment, are a key factor in the infection process. Populations of genetically identical bacteria have been observed to contain both motile cells, generally with 6–10 flagella, and nonmotile cells, with no flagella. In this paper, we use mathematical models of the gene network that regulates flagellar construction to explore how the bacteria controls the number of flagella produced. We suggest that a bacterium must accumulate a threshold amount of a master regulator protein to initiate flagella production and failure to reach the threshold results in no flagella. Downstream mechanisms that impact the amount of master regulator protein are sufficient to determine how many flagella are produced.
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Affiliation(s)
- Kiersten Utsey
- Department of Mathematics, University of Utah, Salt Lake City, Utah, United States of America
| | - James P. Keener
- Departments of Mathematics and Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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Khan F, Tabassum N, Pham DTN, Oloketuyi SF, Kim YM. Molecules involved in motility regulation in Escherichia coli cells: a review. BIOFOULING 2020; 36:889-908. [PMID: 33028083 DOI: 10.1080/08927014.2020.1826939] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 06/11/2023]
Abstract
The initial colonization of the host organism by commensal, probiotic, and pathogenic Escherichia coli strains is an important step in the development of infections and biofilms. Sensing and colonization of host cell surfaces are governed by flagellar and fimbriae/pili appendages, respectively. Biofilm formation confers great advantages on pathogenic E. coli cells such as protection against the host immune system, antimicrobial agents, and several environmental stress factors. The transition from planktonic to sessile physiological states involves several signaling cascades and factors responsible for the regulation of flagellar motility in E. coli cells. These regulatory factors have thus become important targets to control pathogenicity. Hence, attenuation of flagellar motility is considered a potential therapy against pathogenic E. coli. The present review describes signaling pathways and proteins involved in direct or indirect regulation of flagellar motility. Furthermore, application strategies for antimotility natural or synthetic compounds are discussed also.
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Affiliation(s)
- Fazlurrahman Khan
- Institute of Food Science, Pukyong National University, Busan, Republic of Korea
| | - Nazia Tabassum
- Industrial Convergence Bionix Engineering, Pukyong National University, Busan, Republic of Korea
| | - Dung Thuy Nguyen Pham
- Department of Food Science and Technology, Pukyong National University, Busan, Republic of Korea
| | | | - Young-Mog Kim
- Institute of Food Science, Pukyong National University, Busan, Republic of Korea
- Department of Food Science and Technology, Pukyong National University, Busan, Republic of Korea
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Two Tandem Mechanisms Control Bimodal Expression of the Flagellar Genes in Salmonella enterica. J Bacteriol 2020; 202:JB.00787-19. [PMID: 32312744 DOI: 10.1128/jb.00787-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/13/2020] [Indexed: 12/23/2022] Open
Abstract
Flagellar gene expression is bimodal in Salmonella enterica Under certain growth conditions, some cells express the flagellar genes whereas others do not. This results in mixed populations of motile and nonmotile cells. In the present study, we found that two independent mechanisms control bimodal expression of the flagellar genes. One was previously found to result from a double negative-feedback loop involving the flagellar regulators RflP and FliZ. This feedback loop governs bimodal expression of class 2 genes. In this work, a second mechanism was found to govern bimodal expression of class 3 genes. In particular, class 3 gene expression is still bimodal, even when class 2 gene expression is not. Using a combination of experimental and modeling approaches, we found that class 3 bimodality results from the σ28-FlgM developmental checkpoint.IMPORTANCE Many bacterial use flagella to swim in liquids and swarm over surface. In Salmonella enterica, over 50 genes are required to assemble flagella. The expression of these genes is tightly regulated. Previous studies have found that flagellar gene expression is bimodal in S. enterica, which means that only a fraction of cells express flagellar genes and are motile. In the present study, we found that two separate mechanisms induce this bimodal response. One mechanism, which was previously identified, tunes the fraction of motile cells in response to nutrients. The other results from a developmental checkpoint that couples flagellar gene expression to flagellar assembly. Collectively, these results further our understanding of how flagellar gene expression is regulated in S. enterica.
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Non-lethal exposure to H2O2 boosts bacterial survival and evolvability against oxidative stress. PLoS Genet 2020; 16:e1008649. [PMID: 32163413 PMCID: PMC7093028 DOI: 10.1371/journal.pgen.1008649] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 03/24/2020] [Accepted: 02/04/2020] [Indexed: 11/19/2022] Open
Abstract
Unicellular organisms have the prevalent challenge to survive under oxidative stress of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). ROS are present as by-products of photosynthesis and aerobic respiration. These reactive species are even employed by multicellular organisms as potent weapons against microbes. Although bacterial defences against lethal and sub-lethal oxidative stress have been studied in model bacteria, the role of fluctuating H2O2 concentrations remains unexplored. It is known that sub-lethal exposure of Escherichia coli to H2O2 results in enhanced survival upon subsequent exposure. Here we investigate the priming response to H2O2 at physiological concentrations. The basis and the duration of the response (memory) were also determined by time-lapse quantitative proteomics. We found that a low level of H2O2 induced several scavenging enzymes showing a long half-life, subsequently protecting cells from future exposure. We then asked if the phenotypic resistance against H2O2 alters the evolution of resistance against oxygen stress. Experimental evolution of H2O2 resistance revealed faster evolution and higher levels of resistance in primed cells. Several mutations were found to be associated with resistance in evolved populations affecting different loci but, counterintuitively, none of them was directly associated with scavenging systems. Our results have important implications for host colonisation and infections where microbes often encounter reactive oxygen species in gradients. Throughout evolution, bacteria were exposed to reactive oxygen species and evolved the ability to scavenge toxic oxygen radicals. Furthermore, multicellular organisms evolved the ability to produce such oxygen species directed against pathogens. Recent studies also suggest that ROS such as H2O2 play an important role during host gut colonisation by its microbiota. Traditionally, experiments with different antimicrobials have been carried out using fixed concentrations while in nature, including in intra-host environments, microbes are more likely to experience this type of stress in steps or gradients. Here we show that bacteria treated with sub-lethal concentrations of H2O2 (priming) survive far better than non-treated cells when they subsequently encounter a higher concentration. We also found that the 'priming' response has a protective role from lethal mutagenesis. This protection is provided by long-lived proteins that, upon priming, remain at a high level for several generations as determined by time-lapse LC-mass spectrometry. Bacteria that were primed evolved H2O2 resistance faster and to a higher level. Moreover, mutations that increase resistance to H2O2, as determined by whole-genome sequencing (WGS), do not occur in known scavenger encoding genes but in loci coding for other functions, at least in E. coli.
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Romilly C, Hoekzema M, Holmqvist E, Wagner EGH. Small RNAs OmrA and OmrB promote class III flagellar gene expression by inhibiting the synthesis of anti-Sigma factor FlgM. RNA Biol 2020; 17:872-880. [PMID: 32133913 PMCID: PMC7549644 DOI: 10.1080/15476286.2020.1733801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Bacteria can move by a variety of mechanisms, the best understood being flagella-mediated motility. Flagellar genes are organized in a three-tiered cascade allowing for temporally regulated expression that involves both transcriptional and post-transcriptional control. The class I operon encodes the master regulator FlhDC that drives class II gene transcription. Class II genes include fliA and flgM, which encode the Sigma factor σ28, required for class III transcription, and the anti-Sigma factor FlgM, which inhibits σ28 activity, respectively. The flhDC mRNA is regulated by several small regulatory RNAs (sRNAs). Two of these, the sequence-related OmrA and OmrB RNAs, inhibit FlhD synthesis. Here, we report on a second layer of sRNA-mediated control downstream of FhlDC in the flagella pathway. By mutational analysis, we confirm that a predicted interaction between the conserved 5ʹ seed sequences of OmrA/B and the early coding sequence in flgM mRNA reduces FlgM expression. Regulation is dependent on the global RNA-binding protein Hfq. In vitro experiments support a canonical mechanism: binding of OmrA/B prevents ribosome loading and decreases FlgM protein synthesis. Simultaneous inhibition of both FlhD and FlgM synthesis by OmrA/B complicated an assessment of how regulation of FlgM alone impacts class III gene transcription. Using a combinatorial mutation strategy, we were able to uncouple these two targets and demonstrate that OmrA/B-dependent inhibition of FlgM synthesis liberates σ28 to ultimately promote higher expression of the class III flagellin gene fliC.
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Affiliation(s)
- Cédric Romilly
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University , Uppsala, Sweden
| | - Mirthe Hoekzema
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University , Uppsala, Sweden
| | - Erik Holmqvist
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University , Uppsala, Sweden
| | - E Gerhart H Wagner
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University , Uppsala, Sweden
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A Polar Flagellar Transcriptional Program Mediated by Diverse Two-Component Signal Transduction Systems and Basal Flagellar Proteins Is Broadly Conserved in Polar Flagellates. mBio 2020; 11:mBio.03107-19. [PMID: 32127455 PMCID: PMC7064773 DOI: 10.1128/mbio.03107-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Relative to peritrichous bacteria, polar flagellates possess regulatory systems that order flagellar gene transcription differently and produce flagella in specific numbers only at poles. How transcriptional and flagellar biogenesis regulatory systems are interlinked to promote the correct synthesis of polar flagella in diverse species has largely been unexplored. We found evidence for many Gram-negative polar flagellates encoding two-component signal transduction systems with activity linked to the formation of flagellar type III secretion systems to enable production of flagellar rod and hook proteins at a discrete, subsequent stage during flagellar assembly. This polar flagellar transcriptional program assists, in some manner, the FlhF/FlhG flagellar biogenesis regulatory system, which forms specific flagellation patterns in polar flagellates in maintaining flagellation and motility when activity of FlhF or FlhG might be altered. Our work provides insight into the multiple regulatory processes required for polar flagellation. Bacterial flagella are rotating nanomachines required for motility. Flagellar gene expression and protein secretion are coordinated for efficient flagellar biogenesis. Polar flagellates, unlike peritrichous bacteria, commonly order flagellar rod and hook gene transcription as a separate step after production of the MS ring, C ring, and flagellar type III secretion system (fT3SS) core proteins that form a competent fT3SS. Conserved regulatory mechanisms in diverse polar flagellates to create this polar flagellar transcriptional program have not been thoroughly assimilated. Using in silico and genetic analyses and our previous findings in Campylobacter jejuni as a foundation, we observed a large subset of Gram-negative bacteria with the FlhF/FlhG regulatory system for polar flagellation to possess flagellum-associated two-component signal transduction systems (TCSs). We present data supporting a general theme in polar flagellates whereby MS ring, rotor, and fT3SS proteins contribute to a regulatory checkpoint during polar flagellar biogenesis. We demonstrate that Vibrio cholerae and Pseudomonas aeruginosa require the formation of this regulatory checkpoint for the TCSs to directly activate subsequent rod and hook gene transcription, which are hallmarks of the polar flagellar transcriptional program. By reprogramming transcription in V. cholerae to more closely follow the peritrichous flagellar transcriptional program, we discovered a link between the polar flagellar transcription program and the activity of FlhF/FlhG flagellar biogenesis regulators in which the transcriptional program allows polar flagellates to continue to produce flagella for motility when FlhF or FlhG activity may be altered. Our findings integrate flagellar transcriptional and biogenesis regulatory processes involved in polar flagellation in many species.
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Huang WC, Lin CY, Hashimoto M, Wu JJ, Wang MC, Lin WH, Chen CS, Teng CH. The role of the bacterial protease Prc in the uropathogenesis of extraintestinal pathogenic Escherichia coli. J Biomed Sci 2020; 27:14. [PMID: 31900139 PMCID: PMC6941253 DOI: 10.1186/s12929-019-0605-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 12/19/2019] [Indexed: 02/07/2023] Open
Abstract
Background Extraintestinal pathogenic E. coli (ExPEC) remains one of the most prevalent bacterial pathogens that cause extraintestinal infections, including neonatal meningitis, septicemia, and urinary tract (UT) infections (UTIs). Antibiotic therapy has been the conventional treatment for such infections, but its efficacy has decreased due to the emergence of antibiotic-resistant bacteria. Identification and characterization of bacterial factors that contribute to the severity of infection would facilitate the development of novel therapeutic strategies. The ExPEC periplasmic protease Prc contributes to the pathogen’s ability to evade complement-mediated killing in the serum. Here, we further investigated the role of the Prc protease in ExPEC-induced UTIs and the underlying mechanism. Methods The uropathogenic role of Prc was determined in a mouse model of UTIs. Using global quantitative proteomic analyses, we revealed that the expression of FliC and other outer membrane-associated proteins was altered by Prc deficiency. Comparative transcriptome analyses identified that Prc deficiency affected expression of the flagellar regulon and genes that are regulated by five extracytoplasmic signaling systems. Results A mutant ExPEC with a prc deletion was attenuated in bladder and kidney colonization. Global quantitative proteomic analyses of the prc mutant and wild-type ExPEC strains revealed significantly reduced flagellum expression in the absence of Prc, consequently impairing bacterial motility. The prc deletion triggered downregulation of the flhDC operon encoding the master transcriptional regulator of flagellum biogenesis. Overexpressing flhDC restored the prc mutant’s motility and ability to colonize the UT, suggesting that the impaired motility is responsible for attenuated UT colonization of the mutant. Further comparative transcriptome analyses revealed that Prc deficiency activated the σE and RcsCDB signaling pathways. These pathways were responsible for the diminished flhDC expression. Finally, the activation of the RcsCDB system was attributed to the intracellular accumulation of a known Prc substrate Spr in the prc mutant. Spr is a peptidoglycan hydrolase and its accumulation destabilizes the bacterial envelope. Conclusions We demonstrated for the first time that Prc is essential for full ExPEC virulence in UTIs. Our results collectively support the idea that Prc is essential for bacterial envelope integrity, thus explaining how Prc deficiency results in an attenuated ExPEC.
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Affiliation(s)
- Wen-Chun Huang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chung-Yen Lin
- Institute of Information Science, Academia Sinica, Taipei, Taiwan
| | - Masayuki Hashimoto
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
| | - Jiunn-Jong Wu
- Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang Ming University, Taipei, Taiwan
| | - Ming-Cheng Wang
- Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Hung Lin
- Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chang-Shi Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Hao Teng
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. .,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. .,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan.
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Rapid Accumulation of Motility-Activating Mutations in Resting Liquid Culture of Escherichia coli. J Bacteriol 2019; 201:JB.00259-19. [PMID: 31285239 DOI: 10.1128/jb.00259-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
Expression of motility genes is a potentially beneficial but costly process in bacteria. Interestingly, many isolate strains of Escherichia coli possess motility genes but have lost the ability to activate them under conditions in which motility is advantageous, raising the question of how they respond to these situations. Through transcriptome profiling of strains in the E. coli single-gene knockout Keio collection, we noticed drastic upregulation of motility genes in many of the deletion strains compared to levels in their weakly motile parent strain (BW25113). We show that this switch to a motile phenotype is not a direct consequence of the genes deleted but is instead due to a variety of secondary mutations that increase the expression of the major motility regulator, FlhDC. Importantly, we find that this switch can be reproduced by growing poorly motile E. coli strains in nonshaking liquid medium overnight but not in shaking liquid medium. Individual isolates after the nonshaking overnight incubations acquired distinct mutations upstream of the flhDC operon, including different insertion sequence (IS) elements and, to a lesser extent, point mutations. The rapidity with which genetic changes sweep through the populations grown without shaking shows that poorly motile strains can quickly adapt to a motile lifestyle by genetic rewiring.IMPORTANCE The ability to tune gene expression in times of need outside preordained regulatory networks is an essential evolutionary process that allows organisms to survive and compete. Here, we show that upon overnight incubation in liquid medium without shaking, populations of largely nonmotile Escherichia coli bacteria can rapidly accumulate mutants that have constitutive motility. This effect contributes to widespread secondary mutations in the single-gene knockout library, the Keio collection. As a result, 49/71 (69%) of the Keio strains tested exhibited various degrees of motility, whereas their parental strain is poorly motile. These observations highlight the plasticity of gene expression even in the absence of preexisting regulatory programs and should raise awareness of procedures for handling laboratory strains of E. coli.
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Yang CL, Chen XK, Wang R, Lin JQ, Liu XM, Pang X, Zhang CJ, Lin JQ, Chen LX. Essential Role of σ Factor RpoF in Flagellar Biosynthesis and Flagella-Mediated Motility of Acidithiobacillus caldus. Front Microbiol 2019; 10:1130. [PMID: 31178842 PMCID: PMC6543871 DOI: 10.3389/fmicb.2019.01130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/03/2019] [Indexed: 12/04/2022] Open
Abstract
Acidithiobacillaceae, an important family of acidophilic and chemoautotrophic sulfur or iron oxidizers, participate in geobiochemical circulation of the elements and drive the release of heavy metals in mining associated habitats. Because of their environmental adaptability and energy metabolic systems, Acidithiobacillus spp. have become the dominant bacteria used in bioleaching for heavy metal recovery. Flagella-driven motility is associated with bacterial chemotaxis and bacterial responses to environmental stimuli. However, little is known about how the flagellum of Acidithiobacillus spp. is regulated and how the flagellum affects the growth of these chemoautotrophic bacteria. In this study, we analyzed the flagellar gene clusters in Acidithiobacillus strains and uncovered the close relationship between flagella and the sulfur-oxidizing systems (Sox system). The σ28 gene (rpoF) knockout and overexpression strains of Acidithiobacillus caldus were constructed. Scanning electron microscopy shows that A. caldus ΔrpoF cells lacked flagella, indicating the essential role of RpoF in regulating flagella synthesis in these chemoautotrophic bacteria. Motility analysis suggests that the deletion of rpoF resulted in the reduction of swarming capability, while this capability was enhanced in the rpoF overexpression strain. Both static cultivation and low concentration of energy substrates (elemental sulfur or tetrathionate) led to weak growth of A. caldus ΔrpoF cells. The deletion of rpoF promoted bacterial attachment to the surface of elemental sulfur in static cultivation. The absence of RpoF caused an obvious change in transcription profile, including genes in flagellar cluster and those involved in biofilm formation. These results provide an understanding on the regulation of flagellar hierarchy and the flagellar function in these sulfur or iron oxidizers.
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Affiliation(s)
- Chun-Long Yang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xian-Ke Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Rui Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jian-Qiang Lin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xiang-Mei Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xin Pang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Cheng-Jia Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jian-Qun Lin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Lin-Xu Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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Salgado H, Martínez-Flores I, Bustamante VH, Alquicira-Hernández K, García-Sotelo JS, García-Alonso D, Collado-Vides J. Using RegulonDB, the Escherichia coli K-12 Gene Regulatory Transcriptional Network Database. ACTA ACUST UNITED AC 2019; 61:1.32.1-1.32.30. [PMID: 30040192 DOI: 10.1002/cpbi.43] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In RegulonDB, for over 25 years, we have been gathering knowledge by manual curation from original scientific literature on the regulation of transcription initiation and genome organization in transcription units of the Escherichia coli K-12 genome. This unit describes six basic protocols that can serve as a guiding introduction to the main content of the current version (v9.4) of this electronic resource. These protocols include general navigation as well as searching for specific objects such as genes, gene products, transcription units, promoters, transcription factors, coexpression, and genetic sensory response units or GENSOR Units. In these protocols, the user will find an initial introduction to the concepts pertinent to the protocol, the content obtained when performing the given navigation, and the necessary resources for carrying out the protocol. This easy-to-follow presentation should help anyone interested in quickly seeing all that is currently offered in RegulonDB, including position weight matrices of transcription factors, coexpression values based on published microarrays, and the GENSOR Units unique to RegulonDB that offer regulatory mechanisms in the context of their signals and metabolic consequences. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Heladia Salgado
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Irma Martínez-Flores
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Víctor H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Kevin Alquicira-Hernández
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Jair S García-Sotelo
- Laboratorio Internacional de Investigación sobre el Genoma Humano, Universidad Nacional Autónoma de México, Santiago de Querétaro, Querétaro, México
| | - Delfino García-Alonso
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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Abstract
Proteus mirabilis, a Gram-negative rod-shaped bacterium most noted for its swarming motility and urease activity, frequently causes catheter-associated urinary tract infections (CAUTIs) that are often polymicrobial. These infections may be accompanied by urolithiasis, the development of bladder or kidney stones due to alkalinization of urine from urease-catalyzed urea hydrolysis. Adherence of the bacterium to epithelial and catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae. Repressors of motility are often encoded by these fimbrial operons. Motility is mediated by flagella encoded on a single contiguous 54-kb chromosomal sequence. On agar plates, P. mirabilis undergoes a morphological conversion to a filamentous swarmer cell expressing hundreds of flagella. When swarms from different strains meet, a line of demarcation, a "Dienes line," develops due to the killing action of each strain's type VI secretion system. During infection, histological damage is caused by cytotoxins including hemolysin and a variety of proteases, some autotransported. The pathogenesis of infection, including assessment of individual genes or global screens for virulence or fitness factors has been assessed in murine models of ascending urinary tract infections or CAUTIs using both single-species and polymicrobial models. Global gene expression studies performed in culture and in the murine model have revealed the unique metabolism of this bacterium. Vaccines, using MR/P fimbria and its adhesin, MrpH, have been shown to be efficacious in the murine model. A comprehensive review of factors associated with urinary tract infection is presented, encompassing both historical perspectives and current advances.
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Clostridium indicum sp. nov., a novel anaerobic bacterium isolated from the sludge of an industrial effluent. Int J Syst Evol Microbiol 2019; 69:672-678. [DOI: 10.1099/ijsem.0.003199] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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43
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Driving the expression of the Salmonella enterica sv Typhimurium flagellum using flhDC from Escherichia coli results in key regulatory and cellular differences. Sci Rep 2018; 8:16705. [PMID: 30420601 PMCID: PMC6232118 DOI: 10.1038/s41598-018-35005-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/28/2018] [Indexed: 11/09/2022] Open
Abstract
The flagellar systems of Escherichia coli and Salmonella enterica exhibit a significant level of genetic and functional synteny. Both systems are controlled by the flagellar specific master regulator FlhD4C2. Since the early days of genetic analyses of flagellar systems it has been known that E. coli flhDC can complement a ∆flhDC mutant in S. enterica. The genomic revolution has identified how genetic changes to transcription factors and/or DNA binding sites can impact the phenotypic outcome across related species. We were therefore interested in asking: using modern tools to interrogate flagellar gene expression and assembly, what would the impact be of replacing the flhDC coding sequences in S. enterica for the E. coli genes at the flhDC S. entercia chromosomal locus? We show that even though all strains created are motile, flagellar gene expression is measurably lower when flhDCEC are present. These changes can be attributed to the impact of FlhD4C2 DNA recognition and the protein-protein interactions required to generate a stable FlhD4C2 complex. Furthermore, our data suggests that in E. coli the internal flagellar FliT regulatory feedback loop has a marked difference with respect to output of the flagellar systems. We argue due diligence is required in making assumptions based on heterologous expression of regulators and that even systems showing significant synteny may not behave in exactly the same manner.
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Novel Role of VisP and the Wzz System during O-Antigen Assembly in Salmonella enterica Serovar Typhimurium Pathogenesis. Infect Immun 2018; 86:IAI.00319-18. [PMID: 29866904 DOI: 10.1128/iai.00319-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/14/2018] [Indexed: 01/18/2023] Open
Abstract
Salmonella enterica serovars are associated with diarrhea and gastroenteritis and are a helpful model for understanding host-pathogen mechanisms. Salmonella enterica serovar Typhimurium regulates the distribution of O antigen (OAg) and presents a trimodal distribution based on Wzy polymerase and the WzzST (long-chain-length OAg [L-OAg]) and WzzfepE (very-long-chain-length OAg [VL-OAg]) copolymerases; however, several mechanisms regulating this process remain unclear. Here, we report that LPS modifications modulate the infectious process and that OAg chain length determination plays an essential role during infection. An increase in VL-OAg is dependent on Wzy polymerase, which is promoted by a growth condition resembling the environment of Salmonella-containing vacuoles (SCVs). The virulence- and stress-related periplasmic protein (VisP) participates in OAg synthesis, as a ΔvisP mutant presents a semirough OAg phenotype. The ΔvisP mutant has greatly decreased motility and J774 macrophage survival in a colitis model of infection. Interestingly, the phenotype is restored after mutation of the wzzST or wzzfepE gene in a ΔvisP background. Loss of both the visP and wzzST genes promotes an imbalance in flagellin secretion. L-OAg may function as a shield against host immune systems in the beginning of an infectious process, and VL-OAg protects bacteria during SCV maturation and facilitates intramacrophage replication. Taken together, these data highlight the roles of OAg length in generating phenotypes during S Typhimurium pathogenesis and show the periplasmic protein VisP as a novel protein in the OAg biosynthesis pathway.
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Fitzgerald DM, Smith C, Lapierre P, Wade JT. The evolutionary impact of intragenic FliA promoters in proteobacteria. Mol Microbiol 2018; 108:361-378. [PMID: 29476659 PMCID: PMC5943157 DOI: 10.1111/mmi.13941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2018] [Indexed: 12/12/2022]
Abstract
In Escherichia coli, one sigma factor recognizes the majority of promoters, and six 'alternative' sigma factors recognize specific subsets of promoters. The alternative sigma factor FliA (σ28 ) recognizes promoters upstream of many flagellar genes. We previously showed that most E. coli FliA binding sites are located inside genes. However, it was unclear whether these intragenic binding sites represent active promoters. Here, we construct and assay transcriptional promoter-lacZ fusions for all 52 putative FliA promoters previously identified by ChIP-seq. These experiments, coupled with integrative analysis of published genome-scale transcriptional datasets, strongly suggest that most intragenic FliA binding sites are active promoters that transcribe highly unstable RNAs. Additionally, we show that widespread intragenic FliA-dependent transcription may be a conserved phenomenon, but that specific promoters are not themselves conserved. We conclude that intragenic FliA-dependent promoters and the resulting RNAs are unlikely to have important regulatory functions. Nonetheless, one intragenic FliA promoter is broadly conserved and constrains evolution of the overlapping protein-coding gene. Thus, our data indicate that intragenic regulatory elements can influence bacterial protein evolution and suggest that the impact of intragenic regulatory sequences on genome evolution should be considered more broadly.
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Affiliation(s)
- Devon M. Fitzgerald
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, USA
| | - Carol Smith
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Pascal Lapierre
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Joseph T. Wade
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, USA
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
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Ammendola S, D'Amico Y, Chirullo B, Drumo R, Ciavardelli D, Pasquali P, Battistoni A. Zinc is required to ensure the expression of flagella and the ability to form biofilms in Salmonella enterica sv Typhimurium. Metallomics 2017; 8:1131-1140. [PMID: 27730246 DOI: 10.1039/c6mt00108d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Zinc is known to play a central role in bacterial physiology and pathogenesis. Here, we report that the accumulation of FliC, the structural subunit of Salmonella phase 1 flagella, is sharply reduced in a znuABC Salmonella enterica sv. Typhimurium strain grown in zinc-poor media. Consequently, this mutant strain lacks motility, unless it grows in zinc-replete environments. This phenotype is the consequence of a general downregulation of all the genes involved in the biosynthesis of flagella, suggesting that zinc is the cofactor of proteins involved in the initiation of the transcriptional regulatory cascade leading to flagella assembly. Competition experiments in mice demonstrated that aflagellated (fliBfljC) and znuABC strains are outcompeted by the wild type strain in the gastrointestinal tract. The fliBfljC strain overgrows a fliCfljBznuABC mutant strain, but the difference in gut colonization between these two strains is less striking than that between the wild type and the znuABC strains, suggesting that the downregulation of flagella contributes to the loss of virulence of Salmonella znuABC. The absence of either flagella or ZnuABC also impairs the ability of S. Typhimurium to produce biofilms. Zinc suppresses this defect in the znuABC mutant but not in the aflagellated strains, highlighting the role of flagella in biofilm organization. We have also observed an increased production of the quorum sensing signal AI-2 in the znuABC strain sensing zinc deprivation, that may further contribute to the reduced ability to form biofilms. On the whole, our study reveals novel roles of zinc in Salmonella motility and intercellular communication.
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Affiliation(s)
- Serena Ammendola
- Dipartimento di Biologia, Università di Roma "Tor Vergata", Via della Ricerca Scientifica, 00133 Rome, Italy.
| | - Ylenia D'Amico
- Dipartimento di Biologia, Università di Roma "Tor Vergata", Via della Ricerca Scientifica, 00133 Rome, Italy.
| | - Barbara Chirullo
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Rosanna Drumo
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | | | - Paolo Pasquali
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Andrea Battistoni
- Dipartimento di Biologia, Università di Roma "Tor Vergata", Via della Ricerca Scientifica, 00133 Rome, Italy. and Interuniversity Consortium, National Institute Biostructures and Biosystems (INBB), Rome, Italy
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Li B, Yue Y, Yuan Z, Zhang F, Li P, Song N, Lin W, Liu Y, Yang Y, Li Z, Gu L. Salmonella STM1697 coordinates flagella biogenesis and virulence by restricting flagellar master protein FlhD4C2 from recruiting RNA polymerase. Nucleic Acids Res 2017; 45:9976-9989. [PMID: 28973452 PMCID: PMC5622320 DOI: 10.1093/nar/gkx656] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/17/2017] [Indexed: 01/04/2023] Open
Abstract
Salmonella reduces flagella biogenesis to avoid detection within host cells by a largely unknown mechanism. We identified an EAL-like protein STM1697 as required and sufficient for this process. STM1697 surges to a high level after Salmonella enters host cells and restrains the expression of flagellar genes by regulating the function of flagellar switch protein FlhD4C2, the transcription activator of all other flagellar genes. Unlike other anti-FlhD4C2 factors, STM1697 does not prevent FlhD4C2 from binding to target DNA. A 2.0 Å resolution STM1697–FlhD structure reveals that STM1697 binds the same region of FlhD as STM1344, but with weaker affinity. Further experiments show that STM1697 regulates flagella biogenesis by restricting FlhD4C2 from recruiting RNA polymerase and the regulatory effect of STM1697 on flagellar biogenesis and virulence are all achieved by interaction with FlhD. Finally, we describe a novel mechanism mediated by STM1697 in which Salmonella can inhibit the production of flagella antigen and escape from the host immune system.
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Affiliation(s)
- Bingqing Li
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Yingying Yue
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Zenglin Yuan
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Fengyu Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Peng Li
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Nannan Song
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Wei Lin
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Yan Liu
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Yinlong Yang
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China
| | - Zhihui Li
- Key Laboratory of Rare and Uncommon Diseases, Department of Microbiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan 250062, China.,Clinical Laboratory, Liaocheng People's Hospital of Taishan Medical University, Shandong 252000, China
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, China
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Jozwick AKS, Graf J, Welch TJ. The flagellar master operon flhDC is a pleiotropic regulator involved in motility and virulence of the fish pathogen Yersinia ruckeri. J Appl Microbiol 2017; 122:578-588. [PMID: 27981729 DOI: 10.1111/jam.13374] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/14/2016] [Accepted: 11/26/2016] [Indexed: 11/28/2022]
Abstract
AIMS To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of a constructed flhD mutation to a naturally occurring fliR mutation causing loss-of-motility in emergent biotype 2 (BT2) strains. METHODS AND RESULTS Yersinia ruckeri flhD and fliR mutants were constructed in a motile strain. Both mutations caused loss-of-motility, ablation of flagellin synthesis and phospholipase secretion, similar to naturally occurring BT2 strains. Transcriptome analysis confirmed flhDC regulation of flagellar, chemotaxis and phospholipase loci as well as other genes of diverse function. The flhD mutation confers a competitive advantage within the fish host when compared with its parent strain, while this advantage was not seen with the naturally occurring fliR mutation. CONCLUSIONS An intact flhD is necessary for expression of the flagellar secretion system as well as other diverse loci, consistent with a role for flhD as a pleiotropic regulator. The maintenance of the flhD locus in Y. ruckeri strains suggests its importance for aspects of Y. ruckeri biology other than virulence, since the flhD mutation conferred a competitive advantage during experimental challenge of rainbow trout. SIGNIFICANCE AND IMPACT OF THE STUDY Yersinia ruckeri is the causative agent of enteric red mouth disease, an invasive septicaemia that affects farmed salmonid fish species. Disease outbreaks can cause severe economic losses in aquaculture. BT2 variants, which have independently emerged worldwide, are an increasing threat to farmed fish production. Knowledge of mechanisms involved in virulence, conserved functions and gene regulation among strains may be exploited for the development of novel disease control strategies to prevent pathogen growth or virulence phenotypes within aquaculture.
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Affiliation(s)
- A K S Jozwick
- Agricultural Research Service/U.S. Department of Agriculture, National Center for Cool and Cold Water Aquaculture, Kearneysville, WV, USA
| | - J Graf
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA.,Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
| | - T J Welch
- Agricultural Research Service/U.S. Department of Agriculture, National Center for Cool and Cold Water Aquaculture, Kearneysville, WV, USA
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49
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Growth rate control of flagellar assembly in Escherichia coli strain RP437. Sci Rep 2017; 7:41189. [PMID: 28117390 PMCID: PMC5259725 DOI: 10.1038/srep41189] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 12/12/2016] [Indexed: 01/10/2023] Open
Abstract
The flagellum is a rotary motor that enables bacteria to swim in liquids and swarm over surfaces. Numerous global regulators control flagellar assembly in response to cellular and environmental factors. Previous studies have also shown that flagellar assembly is affected by the growth-rate of the cell. However, a systematic study has not yet been described under controlled growth conditions. Here, we investigated the effect of growth rate on flagellar assembly in Escherichia coli using steady-state chemostat cultures where we could precisely control the cell growth-rate. Our results demonstrate that flagellar abundance correlates with growth rate, where faster growing cells produce more flagella. They also demonstrate that this growth-rate dependent control occurs through the expression of the flagellar master regulator, FlhD4C2. Collectively, our results demonstrate that motility is intimately coupled to the growth-rate of the cell.
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50
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Osterman IA, Dikhtyar YY, Bogdanov AA, Dontsova OA, Sergiev PV. Regulation of Flagellar Gene Expression in Bacteria. BIOCHEMISTRY (MOSCOW) 2016; 80:1447-56. [PMID: 26615435 DOI: 10.1134/s000629791511005x] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The flagellum of a bacterium is a supramolecular structure of extreme complexity comprising simultaneously both a unique system of protein transport and a molecular machine that enables the bacterial cell movement. The cascade of expression of genes encoding flagellar components is closely coordinated with the steps of molecular machine assembly, constituting an amazing regulatory system. Data on structure, assembly, and regulation of flagellar gene expression are summarized in this review. The regulatory mechanisms and correlation of the process of regulation of gene expression and flagellum assembly known from the literature are described.
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Affiliation(s)
- I A Osterman
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991, Russia.
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