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Dai Y, Liu R, Yue Y, Song N, Jia H, Ma Z, Gao X, Zhang M, Yuan X, Liu Q, Liu X, Li B, Wang W. A c-di-GMP binding effector STM0435 modulates flagellar motility and pathogenicity in Salmonella. Virulence 2024; 15:2331265. [PMID: 38532247 PMCID: PMC10978029 DOI: 10.1080/21505594.2024.2331265] [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: 09/14/2023] [Accepted: 03/06/2024] [Indexed: 03/28/2024] Open
Abstract
Flagella play a crucial role in the invasion process of Salmonella and function as a significant antigen that triggers host pyroptosis. Regulation of flagellar biogenesis is essential for both pathogenicity and immune escape of Salmonella. We identified the conserved and unknown function protein STM0435 as a new flagellar regulator. The ∆stm0435 strain exhibited higher pathogenicity in both cellular and animal infection experiments than the wild-type Salmonella. Proteomic and transcriptomic analyses demonstrated dramatic increases in almost all flagellar genes in the ∆stm0435 strain compared to wild-type Salmonella. In a surface plasmon resonance assay, purified STM0435 protein-bound c-di-GMP had an affinity of ~8.383 µM. The crystal structures of apo-STM0435 and STM0435&c-di-GMP complex were determined. Structural analysis revealed that R33, R137, and D138 of STM0435 were essential for c-di-GMP binding. A Salmonella with STM1987 (GGDEF protein) or STM4264 (EAL protein) overexpression exhibits completely different motility behaviours, indicating that the binding of c-di-GMP to STM0435 promotes its inhibitory effect on Salmonella flagellar biogenesis.
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Affiliation(s)
- Yuanji Dai
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Ruirui Liu
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Yingying Yue
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & 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 Clinical and Basic Medical Sciences, Shandong First Medical University & 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 Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Zhongrui Ma
- Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Xueyan Gao
- Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Min Zhang
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Xilu Yuan
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Qing Liu
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Xiaoyu Liu
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & 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 Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
- Key Lab for Biotech-Drugs of National Health Commission, Shandong First Medical University, Jinan, Shandong, China
- Key Lab for Rare & Uncommon Diseases of Shandong Province, Jinan, Shandong, 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 Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
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2
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de Oliveira Silva JV, Meneguello JE, Formagio MD, de Freitas CF, Malacarne LC, Marchiosi R, de Mendonça PDSB, Zanetti Campanerut-Sá PA, Graton Mikcha JM. Multi-targets of antimicrobial photodynamic therapy mediated by erythrosine against Staphylococcus aureus identified by proteomic approach. Photochem Photobiol 2024. [PMID: 38594817 DOI: 10.1111/php.13944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/13/2024] [Accepted: 03/06/2024] [Indexed: 04/11/2024]
Abstract
Staphylococcus aureus is a global challenge to the clinical field and food industry. Therefore, the development of antimicrobial photodynamic therapy (aPDT) has become one of the valuable methods to control this pathogen. The antibacterial activity of photoinactivation by erythrosine (Ery) against S. aureus has been reported, but its modes of action are unclear. This study aimed to employ a proteomic approach to analyze modes of action of Ery-aPDT against S. aureus. We determined the antibacterial effect by Ery-aPDT assays, quantified reactive oxygen species (ROS) and injury to the cell membrane, and determined protein expression using a proteomic approach combined with bioinformatic tools. Ery-aPDT was effective in reducing S. aureus to undetectable levels. In addition, the increment of ROS accompanied the increase in the reduction of cell viability, and damage to cellular membranes was shown by sublethal injury. In proteomic analysis, we found 17 differentially expressed proteins. These proteins revealed changes mainly associated with defense to oxidative stress, energy metabolism, translation, and protein biosynthesis. Thus, these results suggest that the effectiveness of Ery-aPDT is due to multi-targets in the bacterial cell that cause the death of S. aureus.
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Affiliation(s)
| | - Jean Eduardo Meneguello
- Department of Clinical Analysis and Biomedicine, State University of Maringá, Paraná, Brazil
| | - Maíra Dante Formagio
- Department of Clinical Analysis and Biomedicine, State University of Maringá, Paraná, Brazil
| | | | | | - Rogério Marchiosi
- Department of Biochemistry, State University of Maringá, Paraná, Brazil
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3
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Tang J, Hu Z, Zhang J, Daroch M. Genome-scale identification and comparative analysis of transcription factors in thermophilic cyanobacteria. BMC Genomics 2024; 25:44. [PMID: 38195395 PMCID: PMC10775510 DOI: 10.1186/s12864-024-09969-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 01/03/2024] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND The transcription factors (TFs) in thermophilic cyanobacteria might represent a uniquely evolved gene repertoire in light of the strong selective pressure caused by hostile habitats. Understanding the molecular composition of the TF genes in thermophilic cyanobacteria will facilitate further studies regarding verifying their exact biochemical functions and genetic engineering. However, limited information is available on the TFs of thermophilic cyanobacteria. Herein, a thorough investigation and comparative analysis were performed to gain insights into the molecular composition of the TFs in 22 thermophilic cyanobacteria. RESULTS The results suggested a fascinating diversity of the TFs among these thermophiles. The abundance and type of TF genes were diversified in these genomes. The identified TFs are speculated to play various roles in biological regulations. Further comparative and evolutionary genomic analyses revealed that HGT may be associated with the genomic plasticity of TF genes in Thermostichus and Thermosynechococcus strains. Comparative analyses also indicated different pattern of TF composition between thermophiles and corresponding mesophilic reference cyanobacteria. Moreover, the identified unique TFs of thermophiles are putatively involved in various biological regulations, mainly as responses to ambient changes, may facilitating the thermophiles to survive in hot springs. CONCLUSION The findings herein shed light on the TFs of thermophilic cyanobacteria and fundamental knowledge for further research regarding thermophilic cyanobacteria with a broad potential for transcription regulations in responses to environmental fluctuations.
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Affiliation(s)
- Jie Tang
- School of Pharmacy and Bioengineering, Chengdu University, Chengdu, 610106, China
| | - Zhe Hu
- School of Pharmacy and Bioengineering, Chengdu University, Chengdu, 610106, China
| | - Jing Zhang
- Food Safety Detection Key Laboratory of Sichuan, Technical Center of Chengdu Customs, Chengdu, 610041, China.
| | - Maurycy Daroch
- School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.
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4
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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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5
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Ishikawa F, Homma M, Tanabe G, Uchihashi T. [Protein degradation in bacteria: focus on the ClpP protease]. Nihon Saikingaku Zasshi 2024; 79:1-13. [PMID: 38382970 DOI: 10.3412/jsb.79.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Proteins in the cells are born (synthesized), work, and die (decomposed). In the life of a protein, its birth is obviously important, but how it dies is equally important in living organisms. Proteases secreted into the outside of cells are used to decompose the external proteins and the degradation products are taken as the nutrients. On the other hand, there are also proteases that decompose unnecessary or harmful proteins which are generated in the cells. In eukaryotes, a large enzyme complex called the proteasome is primarily responsible for degradation of such proteins. Bacteria, which are prokaryotes, have a similar system as the proteasome. We would like to explain the bacterial degradation system of proteins or the death of proteins, which is performed by ATP-dependent protease Clp, with a particular focus on the ClpXP complex, and with an aspect as a target for antibiotics against bacteria.
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Affiliation(s)
| | - Michio Homma
- Division of Physics, Graduate School of Science, Nagoya University
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López-Yglesias AH, Lu CC, Lai MA, Quarles EK, Zhao X, Hajjar AM, Smith KD. FlgM is required to evade NLRC4-mediated host protection against flagellated Salmonella. Infect Immun 2023; 91:e0025523. [PMID: 37638725 PMCID: PMC10501211 DOI: 10.1128/iai.00255-23] [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: 07/05/2023] [Accepted: 07/07/2023] [Indexed: 08/29/2023] Open
Abstract
Salmonella enterica serovar Typhimurium is a leading cause of gastroenteritis worldwide and a deadly pathogen in children, immunocompromised patients, and the elderly. Salmonella induces innate immune responses through the NLRC4 inflammasome, which has been demonstrated to have distinct roles during systemic and mucosal detections of flagellin and non-flagellin molecules. We hypothesized that NLRC4 recognition of Salmonella flagellin is the dominant protective pathway during infection. To test this hypothesis, we used wild-type, flagellin-deficient, and flagellin-overproducing Salmonella to establish the role of flagellin in mediating NLRC4-dependent host resistance during systemic and mucosal infections in mice. We observed that during the systemic phase of infection, Salmonella efficiently evades NLRC4-mediated innate immunity. During mucosal Salmonella infection, flagellin recognition by the NLRC4 inflammasome pathway is the dominant mediator of protective innate immunity. Deletion of flgM results in constitutive expression of flagellin and severely limits systemic and mucosal Salmonella infections in an NLRC4 inflammasome-dependent manner. These data establish that recognition of Salmonella's flagellin by the NLRC4 inflammasome during mucosal infection is the dominant innate protective pathway for host resistance against the enteric pathogen and that FlgM-mediated evasion of the NLRC4 inflammasome enhances virulence and intestinal tissue destruction.
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Affiliation(s)
| | - Chun-Chi Lu
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Marvin A. Lai
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Ellen K. Quarles
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Xiaodan Zhao
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Adeline M. Hajjar
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Kelly D. Smith
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
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7
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Hou C, Liu L, Ju X, Xiao Y, Li B, You C. Revisiting Fur Regulon Leads to a Comprehensive Understanding of Iron and Fur Regulation. Int J Mol Sci 2023; 24:ijms24109078. [PMID: 37240425 DOI: 10.3390/ijms24109078] [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: 03/20/2023] [Revised: 05/16/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Iron is an essential element because it functions as a cofactor of many enzymes, but excess iron causes cell damage. Iron hemostasis in Escherichia coli was transcriptionally maintained by the ferric uptake regulator (Fur). Despite having been studied extensively, the comprehensive physiological roles and mechanisms of Fur-coordinated iron metabolism still remain obscure. In this work, by integrating a high-resolution transcriptomic study of the Fur wild-type and knockout Escherichia coli K-12 strains in the presence or absence of iron with high-throughput ChIP-seq assay and physiological studies, we revisited the regulatory roles of iron and Fur systematically and discovered several intriguing features of Fur regulation. The size of the Fur regulon was expanded greatly, and significant discrepancies were observed to exist between the regulations of Fur on the genes under its direct repression and activation. Fur showed stronger binding strength to the genes under its repression, and genes that were repressed by Fur were more sensitive to Fur and iron regulation as compared to the genes that were activated by Fur. Finally, we found that Fur linked iron metabolism to many essential processes, and the systemic regulations of Fur on carbon metabolism, respiration, and motility were further validated or discussed. These results highlight how Fur and Fur-controlled iron metabolism affect many cellular processes in a systematic way.
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Affiliation(s)
- Chaofan Hou
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Lin Liu
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Xian Ju
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Yunzhu Xiao
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Bingyu Li
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Conghui You
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
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8
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Derdouri N, Ginet N, Denis Y, Ansaldi M, Battesti A. The prophage-encoded transcriptional regulator AppY has pleiotropic effects on E. coli physiology. PLoS Genet 2023; 19:e1010672. [PMID: 36930675 PMCID: PMC10057817 DOI: 10.1371/journal.pgen.1010672] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/29/2023] [Accepted: 02/18/2023] [Indexed: 03/18/2023] Open
Abstract
Bacterial genome diversity is influenced by prophages, which are viral genomes integrated into the bacterial chromosome. Most prophage genes are silent but those that are expressed can provide unexpected properties to their host. Using as a model E. coli K-12 that carries 9 defective prophages in its genome, we aimed at highlighting the impact of genes encoded by prophages on host physiology. We focused our work on AppY, a transcriptional regulator encoded on the DLP12 prophage. By performing RNA-Seq experiments, we showed that AppY production modulates the expression of more than 200 genes. Among them, 11 were identified by ChIP-Seq as direct AppY targets. AppY directly and positively regulates several genes involved in the acid stress response including the master regulator gene gadE but also nhaR and gadY, two genes important for biofilm formation. Moreover, AppY indirectly and negatively impacts bacterial motility by favoring the degradation of FlhDC, the master regulator of the flagella biosynthesis. As a consequence of these regulatory effects, AppY increases acid stress resistance and biofilm formation while also causing a strong defect in motility. Our research shed light on the importance to consider the genetic interactions occurring between prophages and bacteria to fully understand bacterial physiology. It also highlights how a prophage-encoded transcriptional regulator integrates in a complex manner into the host regulatory network and how it benefits its host, allowing it to cope with changing environmental conditions.
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Affiliation(s)
- Naoual Derdouri
- Aix Marseille Université, Centre National de la Recherche Scientifique, Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - Nicolas Ginet
- Aix Marseille Université, Centre National de la Recherche Scientifique, Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - Yann Denis
- Aix Marseille Université, Centre National de la Recherche Scientifique, Plateforme Transcriptome, Institut de Microbiologie de la Méditerranée-, Marseille, France
| | - Mireille Ansaldi
- Aix Marseille Université, Centre National de la Recherche Scientifique, Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - Aurélia Battesti
- Aix Marseille Université, Centre National de la Recherche Scientifique, Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Marseille, France
- * E-mail:
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9
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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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10
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Wang W, Yue Y, Zhang M, Song N, Jia H, Dai Y, Zhang F, Li C, Li B. Host acid signal controls Salmonella flagella biogenesis through CadC-YdiV axis. Gut Microbes 2022; 14:2146979. [PMID: 36456534 PMCID: PMC9728131 DOI: 10.1080/19490976.2022.2146979] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Upon entering host cells, Salmonella quickly turns off flagella biogenesis to avoid recognition by the host immune system. However, it is not clear which host signal(s) Salmonella senses to initiate flagellum control. Here, we demonstrate that the acid signal can suppress flagella synthesis and motility of Salmonella, and this occurs after the transcription of master flagellar gene flhDC and depends on the anti-FlhDC factor YdiV. YdiV expression is activated after acid treatment. A global screen with ydiV promoter DNA and total protein from acid-treated Salmonella revealed a novel regulator of YdiV, the acid-related transcription factor CadC. Further studies showed that CadCC, the DNA binding domain of CadC, directly binds to a 33 nt region of the ydiV promoter with a 0.2 μM KD affinity. Furthermore, CadC could separate H-NS-ydiV promoter DNA complex to form CadC-DNA complex at a low concentration. Structural simulation and mutagenesis assays revealed that H43 and W106 of CadC are essential for ydiV promoter binding. No acid-induced flagellum control phenotype was observed in cadC mutant or ydiV mutant strains, suggesting that flagellum control during acid adaption is dependent on CadC and YdiV. The intracellular survival ability of cadC mutant strain decreased significantly compared with WT strain while the flagellin expression could not be effectively controlled in the cadC mutant strain when surviving within host cells. Together, our results demonstrated that acid stress acts as an important host signal to trigger Salmonella flagellum control through the CadC-YdiV-FlhDC axis, allowing Salmonella to sense a hostile environment and regulate flagellar synthesis during infection.
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Affiliation(s)
- Weiwei Wang
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yingying Yue
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Min Zhang
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Nannan Song
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Haihong Jia
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yuanji Dai
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Fengyu Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, China
| | - Cuiling Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Bingqing Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China,Shandong First Medical University, Key Lab for Biotech-Drugs of National Health Commission, Jinan, China,KeyLaboratory for Rare & Uncommon Diseases of Shandong Province, Jinan, China,CONTACT Bingqing Li Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan250021Shandong, China
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11
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Aljghami ME, Barghash MM, Majaesic E, Bhandari V, Houry WA. Cellular functions of the ClpP protease impacting bacterial virulence. Front Mol Biosci 2022; 9:1054408. [PMID: 36533084 PMCID: PMC9753991 DOI: 10.3389/fmolb.2022.1054408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 11/15/2022] [Indexed: 09/28/2023] Open
Abstract
Proteostasis mechanisms significantly contribute to the sculpting of the proteomes of all living organisms. ClpXP is a central AAA+ chaperone-protease complex present in both prokaryotes and eukaryotes that facilitates the unfolding and subsequent degradation of target substrates. ClpX is a hexameric unfoldase ATPase, while ClpP is a tetradecameric serine protease. Substrates of ClpXP belong to many cellular pathways such as DNA damage response, metabolism, and transcriptional regulation. Crucially, disruption of this proteolytic complex in microbes has been shown to impact the virulence and infectivity of various human pathogenic bacteria. Loss of ClpXP impacts stress responses, biofilm formation, and virulence effector protein production, leading to decreased pathogenicity in cell and animal infection models. Here, we provide an overview of the multiple critical functions of ClpXP and its substrates that modulate bacterial virulence with examples from several important human pathogens.
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Affiliation(s)
- Mazen E. Aljghami
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Marim M. Barghash
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Emily Majaesic
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
| | - Vaibhav Bhandari
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Walid A. Houry
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
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12
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Schwarz M, Hübner I, Sieber SA. Tailored phenyl esters inhibit ClpXP and attenuate Staphylococcus aureus α-hemolysin secretion. Chembiochem 2022; 23:e202200253. [PMID: 35713329 PMCID: PMC9544270 DOI: 10.1002/cbic.202200253] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/15/2022] [Indexed: 11/14/2022]
Abstract
Novel strategies against multidrug‐resistant bacteria are urgently needed in order to overcome the current silent pandemic. Manipulation of toxin production in pathogenic species serves as a promising approach to attenuate virulence and prevent infections. In many bacteria such as Staphylococcus aureus or Listeria monocyotgenes, serine protease ClpXP is a key contributor to virulence and thus represents a prime target for antimicrobial drug discovery. The limited stability of previous electrophilic warheads has prevented a sustained effect of virulence attenuation in bacterial culture. Here, we systematically tailor the stability and inhibitory potency of phenyl ester ClpXP inhibitors by steric shielding of the ester bond and fine‐tuning the phenol leaving group. Out of 17 derivatives, two (MAS‐19 and MAS‐30) inhibited S. aureus ClpP peptidase and ClpXP protease activities by >60 % at 1 μM. Furthermore, the novel inhibitors did not exhibit pronounced cytotoxicity against human and bacterial cells. Unlike the first generation phenylester AV170, these molecules attenuated S. aureus virulence markedly and displayed increased stability in aqueous buffer compared to the previous benchmark AV170.
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Affiliation(s)
- Markus Schwarz
- Technical University Munich: Technische Universitat Munchen, Chemistry, Ernst-Otto-Fischer-Straße 8, 85748, Garching bei München, GERMANY
| | - Ines Hübner
- Technical University of Munich: Technische Universitat Munchen, Chemistry, GERMANY
| | - Stephan Axel Sieber
- Technische Universitat Munchen, Department of Chemistry, Lichtenbergstr. 4, 85747, Garching, GERMANY
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13
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Wang W, Yue Y, Zhang M, Song N, Jia H, Dai Y, Zhang F, Li C, Li B. Host acid signal controls Salmonella flagella biogenesis through CadC-YdiV axis. Gut Microbes 2022. [PMID: 36456534 DOI: 10.1080/194909762125747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
Upon entering host cells, Salmonella quickly turns off flagella biogenesis to avoid recognition by the host immune system. However, it is not clear which host signal(s) Salmonella senses to initiate flagellum control. Here, we demonstrate that the acid signal can suppress flagella synthesis and motility of Salmonella, and this occurs after the transcription of master flagellar gene flhDC and depends on the anti-FlhDC factor YdiV. YdiV expression is activated after acid treatment. A global screen with ydiV promoter DNA and total protein from acid-treated Salmonella revealed a novel regulator of YdiV, the acid-related transcription factor CadC. Further studies showed that CadCC, the DNA binding domain of CadC, directly binds to a 33 nt region of the ydiV promoter with a 0.2 μM KD affinity. Furthermore, CadC could separate H-NS-ydiV promoter DNA complex to form CadC-DNA complex at a low concentration. Structural simulation and mutagenesis assays revealed that H43 and W106 of CadC are essential for ydiV promoter binding. No acid-induced flagellum control phenotype was observed in cadC mutant or ydiV mutant strains, suggesting that flagellum control during acid adaption is dependent on CadC and YdiV. The intracellular survival ability of cadC mutant strain decreased significantly compared with WT strain while the flagellin expression could not be effectively controlled in the cadC mutant strain when surviving within host cells. Together, our results demonstrated that acid stress acts as an important host signal to trigger Salmonella flagellum control through the CadC-YdiV-FlhDC axis, allowing Salmonella to sense a hostile environment and regulate flagellar synthesis during infection.
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Affiliation(s)
- Weiwei Wang
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yingying Yue
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Min Zhang
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Nannan Song
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Haihong Jia
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yuanji Dai
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Fengyu Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, China
| | - Cuiling Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Bingqing Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
- Shandong First Medical University, Key Lab for Biotech-Drugs of National Health Commission, Jinan, China
- KeyLaboratory for Rare & Uncommon Diseases of Shandong Province, Jinan, China
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14
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Li B, Hou C, Ju X, Feng Y, Ye ZQ, Xiao Y, Gu M, Fu C, Wei C, You C. Gain of Spontaneous clpX Mutations Boosting Motility via Adaption to Environments in Escherichia coli. Front Bioeng Biotechnol 2021; 9:772397. [PMID: 34900963 PMCID: PMC8652233 DOI: 10.3389/fbioe.2021.772397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/25/2021] [Indexed: 11/22/2022] Open
Abstract
Motility is finely regulated and is crucial to bacterial processes including colonization and biofilm formation. There is a trade-off between motility and growth in bacteria with molecular mechanisms not fully understood. Hypermotile Escherichia coli could be isolated by evolving non-motile cells on soft agar plates. Most of the isolates carried mutations located upstream of the flhDC promoter region, which upregulate the transcriptional expression of the master regulator of the flagellum biosynthesis, FlhDC. Here, we identified that spontaneous mutations in clpX boosted the motility of E. coli largely, inducing several folds of changes in swimming speed. Among the mutations identified, we further elucidated the molecular mechanism underlying the ClpXV78F mutation on the regulation of E. coli motility. We found that the V78F mutation affected ATP binding to ClpX, resulting in the inability of the mutated ClpXP protease to degrade FlhD as indicated by both structure modeling and in vitro protein degradation assays. Moreover, our proteomic data indicated that the ClpXV78F mutation elevated the stability of known ClpXP targets to various degrees with FlhD as one of the most affected. In addition, the specific tag at the C-terminus of FlhD being recognized for ClpXP degradation was identified. Finally, our transcriptome data characterized that the enhanced expression of the motility genes in the ClpXV78F mutations was intrinsically accompanied by the reduced expression of stress resistance genes relating to the reduced fitness of the hypermotile strains. A similar pattern was observed for previously isolated hypermotile E. coli strains showing high expression of flhDC at the transcriptional level. Hence, clpX appears to be a hot locus comparable to the upstream of the flhDC promoter region evolved to boost bacterial motility, and our finding provides insight into the reduced fitness of the hypermotile bacteria.
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Affiliation(s)
- Bingyu Li
- Guangdong Key Laboratory for Genome Stability and Disease Prevention, Health Science Center, Shenzhen University, Shenzhen, China.,Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen, China.,Shandong Provincial Key Laboratory of Energy Genetics, Key Laboratory of Biofuels, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Chaofan Hou
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen, China
| | - Xian Ju
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen, China
| | - Yong Feng
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen, China
| | - Zhi-Qiang Ye
- Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Yunzhu Xiao
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen, China
| | - Mingyao Gu
- Guangdong Key Laboratory for Genome Stability and Disease Prevention, Health Science Center, Shenzhen University, Shenzhen, China
| | - Chunxiang Fu
- Shandong Provincial Key Laboratory of Energy Genetics, Key Laboratory of Biofuels, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Chaoliang Wei
- Guangdong Key Laboratory for Genome Stability and Disease Prevention, Health Science Center, Shenzhen University, Shenzhen, China
| | - Conghui You
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen, China
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15
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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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16
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Sun X, Kawata K, Miki A, Wada Y, Nagahama M, Takaya A, Akimitsu N. Exploration of Salmonella effector mutant strains on MTR4 and RRP6 degradation. Biosci Trends 2020; 14:255-262. [PMID: 32350160 DOI: 10.5582/bst.2020.03085] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Salmonella enterica serovar Typhimurium (Salmonella), a pathogenic bacterium, is a major cause of foodborne diseases worldwide. Salmonella injects multiple virulence factors, called effectors, into cells and causes multiple rearrangements of cellular biological reactions that are important for Salmonella proliferation and virulence. Previously, we reported that Salmonella infection causes loss of MTR4 and RRP6, which are nuclear RNA degradation factors, resulting in the stabilization and accumulation of unstable nuclear RNAs. This accumulation is important for the cellular defense for Salmonella infection. In this study, we examined a series of Salmonella mutant strains, most of which are strains with genes related to effectors translocated by T3SSs encoded on Salmonella pathogenic islands, SPI-1 and SPI-2, that have been depleted. Among 42 Salmonella mutants, 6 mutants' infections canceled loss of MTR4 and RRP6. Proliferation assay of Salmonella in the cell revealed that six mutants showed poor proliferation in the host cell, demonstrating that poor proliferation contributed to cancellation of MTR4 and RRP6 loss. This result indicates that certain events associated with Salmonella proliferation in host cells cause loss of MTR4 and RRP6.
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Affiliation(s)
- Xiaoning Sun
- Isotope Science Center, The University of Tokyo, Tokyo, Japan.,Advanced Interdisciplinary Studies, Engineering Department, The University of Tokyo, Tokyo, Japan
| | - Kentaro Kawata
- Isotope Science Center, The University of Tokyo, Tokyo, Japan
| | - Atsuko Miki
- Isotope Science Center, The University of Tokyo, Tokyo, Japan
| | - Youichiro Wada
- Isotope Science Center, The University of Tokyo, Tokyo, Japan.,Advanced Interdisciplinary Studies, Engineering Department, The University of Tokyo, Tokyo, Japan
| | - Masami Nagahama
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
| | - Akiko Takaya
- Department of Natural Products Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.,Medical Mycology Research Center, Chiba University, Chiba, Japan
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17
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Jin L, Li T, Wu B, Yang T, Zou D, Liang X, Hu L, Huang G, Zhang J. Rapid detection of Salmonella in milk by nuclear magnetic resonance based on membrane filtration superparamagnetic nanobiosensor. Food Control 2020. [DOI: 10.1016/j.foodcont.2019.107011] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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18
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Improving Our Understanding of Salmonella enterica Serovar Paratyphi B through the Engineering and Testing of a Live Attenuated Vaccine Strain. mSphere 2018; 3:3/6/e00474-18. [PMID: 30487152 PMCID: PMC6262260 DOI: 10.1128/msphere.00474-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We developed a live attenuated Salmonella enterica serovar Paratyphi B vaccine that conferred protection in mice against challenge with S. Paratyphi B sensu stricto and S. Paratyphi B Java, which are the causes of enteric fever and gastroenteritis, respectively. Currently, the incidence of invasive S. Paratyphi B sensu stricto infections is low; however, the development of new conjugate vaccines against other enteric fever serovars could lead to the emergence of S. Paratyphi B to fill the niche left by these other pathogens. As such, an effective S. Paratyphi B vaccine would be a useful tool in the armamentarium against Salmonella infections. Comparative genomics confirmed the serovar-specific groupings of these isolates and revealed that there are a limited number of genetic differences between the sensu stricto and Java strains, which are mostly hypothetical and phage-encoded proteins. The observed level of genomic similarity likely explains why we observe some cross-protection. Enteric fever is caused by three Salmonella enterica serovars: Typhi, Paratyphi A, and Paratyphi B sensu stricto. Although vaccines against two of these serovars are licensed (Typhi) or in clinical development (Paratyphi A), as yet there are no candidates for S. Paratyphi B. To gain genomic insight into these serovars, we sequenced 38 enteric fever-associated strains from Chile and compared these with reference genomes. Each of the serovars was separated genomically based on the core genome. Genomic comparisons identified loci that were aberrant between serovars Paratyphi B sensu stricto and Paratyphi B Java, which is typically associated with gastroenteritis; however, the majority of these were annotated as hypothetical or phage related and thus were not ideal vaccine candidates. With the genomic information in hand, we engineered a live attenuated S. Paratyphi B sensu stricto vaccine strain, CVD 2005, which was capable of protecting mice from both homologous challenge and heterologous challenge with S. Paratyphi B Java. These findings extend our understanding of S. Paratyphi B and provide a viable vaccine option for inclusion in a trivalent live attenuated enteric fever vaccine formulation. IMPORTANCE We developed a live attenuated Salmonella enterica serovar Paratyphi B vaccine that conferred protection in mice against challenge with S. Paratyphi B sensu stricto and S. Paratyphi B Java, which are the causes of enteric fever and gastroenteritis, respectively. Currently, the incidence of invasive S. Paratyphi B sensu stricto infections is low; however, the development of new conjugate vaccines against other enteric fever serovars could lead to the emergence of S. Paratyphi B to fill the niche left by these other pathogens. As such, an effective S. Paratyphi B vaccine would be a useful tool in the armamentarium against Salmonella infections. Comparative genomics confirmed the serovar-specific groupings of these isolates and revealed that there are a limited number of genetic differences between the sensu stricto and Java strains, which are mostly hypothetical and phage-encoded proteins. The observed level of genomic similarity likely explains why we observe some cross-protection.
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19
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Shih HY, Mickalide H, Fraebel DT, Goldenfeld N, Kuehn S. Biophysical constraints determine the selection of phenotypic fluctuations during directed evolution. Phys Biol 2018; 15:065003. [PMID: 29762139 DOI: 10.1088/1478-3975/aac4e6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Phenotypes of individuals in a population of organisms are not fixed. Phenotypic fluctuations, which describe temporal variation of the phenotype of an individual or individual-to-individual variation across a population, are present in populations from microbes to higher animals. Phenotypic fluctuations can provide a basis for adaptation and be the target of selection. Here we present a theoretical and experimental investigation of the fate of phenotypic fluctuations in directed evolution experiments where phenotypes are subject to constraints. We show that selecting bacterial populations for fast migration through a porous environment drives a reduction in cell-to-cell variation across the population. Using sequencing and genetic engineering we study the genetic basis for this reduction in phenotypic fluctuations. We study the generality of this reduction by developing a simple, abstracted, numerical simulation model of the evolution of phenotypic fluctuations subject to constraints. Using this model we find that strong and weak selection generally lead respectively to increasing or decreasing cell-to-cell variation as a result of a bound on the selected phenotype under a wide range of parameters. However, other behaviors are also possible, and we describe the outcome of selection simulations for different model parameters and suggest future experiments. We analyze the mechanism of the observed reduction of phenotypic fluctuations in our experimental system, discuss the relevance of our abstract model to the experiment and explore its broader implications for evolution.
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Affiliation(s)
- Hong-Yan Shih
- Department of Physics and Center for the Physics of Living Cells, Loomis Laboratory of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, IL 61801, United States of America
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20
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Mitsunaka S, Sudo N, Sekine Y. Lysogenisation of Shiga toxin-encoding bacteriophage represses cell motility. J GEN APPL MICROBIOL 2017; 64:34-41. [PMID: 29225287 DOI: 10.2323/jgam.2017.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Bacteriophages are genetic elements that play key roles in the evolution and diversification of bacterial genomes. The Shiga toxin (Stx)-encoding phage plays an important role in the horizontal transfer of the stx gene. However, the influence of the Stx phage integration on the physiological properties and gene expression pattern of the host have not been clearly resolved. In this study, we constructed the Sp5 lysogen through lysogenisation of E. coli K-12 by Sp5, an Stx2 phage in enterohaemorrhagic E. coli (EHEC) O157:H7 Sakai, and examined the effect of the resulting lysogen on cell motility under various growth conditions. Sp5 lysogenisation decreased cell motility and the expression of fliC, which encodes flagellin, under anaerobic conditions at 37°C. Sp5 also lowered the expression of fliA, which encodes the FliA-sigma factor responsible for the transcription of fliC, and flhD, which facilitates the expression of fliA. Sp5 lysogenisation reduced the amount of FlhD and FlhC expressed from the araBAD promoter, suggesting that one or more genes present in Sp5 represses flhDC at the post-transcriptional level. Flagellin is highly antigenic and triggers an immune response in the host. Thus, Sp5 might enhance its viability by repressing the expression of the flagellar regulon to circumvent the immune response of host cells.
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Affiliation(s)
| | - Naoki Sudo
- Department of Life Science, College of Science, Rikkyo University
| | - Yasuhiko Sekine
- Department of Life Science, College of Science, Rikkyo University
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21
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Lee JH, Zhao Y. ClpXP-Dependent RpoS Degradation Enables Full Activation of Type III Secretion System, Amylovoran Production, and Motility in Erwinia amylovora. PHYTOPATHOLOGY 2017; 107:1346-1352. [PMID: 28691868 DOI: 10.1094/phyto-06-17-0198-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Erwinia amylovora, the causal agent of fire blight disease of apple and pear, employs intracellular proteases, including Lon and ClpXP, for posttranslational regulation of various cellular proteins. It has been shown that Lon plays a critical role in E. amylovora virulence by directly targeting type III secretion system (T3SS) proteins and the Rcs phosphorelay system. In this study, we genetically examined the role of ClpXP and its potential interaction with Lon in E. amylovora. Mutation in clpXP diminished the expression of the T3SS, reduced exopolysaccharide amylovoran production and motility, and resulted in delayed disease progress. Western blot analyses showed highly accumulated RpoS proteins in the clpXP mutant. Moreover, mutation of rpoS in the clpXP mutant background rescued the expression of the T3SS and amylovoran production, suggesting that ClpXP-dependent RpoS degradation positively affects virulence traits. Interestingly, lack of both ClpXP and Lon resulted in significantly reduced virulence but increased expression of the T3SS and amylovoran production. However, this phenomenon was independent of RpoS accumulation, suggesting that ClpXP and Lon are indispensable for full virulence in E. amylovora.
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Affiliation(s)
- Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
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22
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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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23
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Novel genes associated with enhanced motility of Escherichia coli ST131. PLoS One 2017; 12:e0176290. [PMID: 28489862 PMCID: PMC5425062 DOI: 10.1371/journal.pone.0176290] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 04/07/2017] [Indexed: 12/20/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) is the cause of ~75% of all urinary tract infections (UTIs) and is increasingly associated with multidrug resistance. This includes UPEC strains from the recently emerged and globally disseminated sequence type 131 (ST131), which is now the dominant fluoroquinolone-resistant UPEC clone worldwide. Most ST131 strains are motile and produce H4-type flagella. Here, we applied a combination of saturated Tn5 mutagenesis and transposon directed insertion site sequencing (TraDIS) as a high throughput genetic screen and identified 30 genes associated with enhanced motility of the reference ST131 strain EC958. This included 12 genes that repress motility of E. coli K-12, four of which (lrhA, ihfA, ydiV, lrp) were confirmed in EC958. Other genes represented novel factors that impact motility, and we focused our investigation on characterisation of the mprA, hemK and yjeA genes. Mutation of each of these genes in EC958 led to increased transcription of flagellar genes (flhD and fliC), increased expression of the FliC flagellin, enhanced flagella synthesis and a hyper-motile phenotype. Complementation restored all of these properties to wild-type level. We also identified Tn5 insertions in several intergenic regions (IGRs) on the EC958 chromosome that were associated with enhanced motility; this included flhDC and EC958_1546. In both of these cases, the Tn5 insertions were associated with increased transcription of the downstream gene(s), which resulted in enhanced motility. The EC958_1546 gene encodes a phage protein with similarity to esterase/deacetylase enzymes involved in the hydrolysis of sialic acid derivatives found in human mucus. We showed that over-expression of EC958_1546 led to enhanced motility of EC958 as well as the UPEC strains CFT073 and UTI89, demonstrating its activity affects the motility of different UPEC strains. Overall, this study has identified and characterised a number of novel factors associated with enhanced UPEC motility.
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24
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Fraebel DT, Mickalide H, Schnitkey D, Merritt J, Kuhlman TE, Kuehn S. Environment determines evolutionary trajectory in a constrained phenotypic space. eLife 2017; 6. [PMID: 28346136 PMCID: PMC5441876 DOI: 10.7554/elife.24669] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 03/25/2017] [Indexed: 12/18/2022] Open
Abstract
Constraints on phenotypic variation limit the capacity of organisms to adapt to the multiple selection pressures encountered in natural environments. To better understand evolutionary dynamics in this context, we select Escherichia coli for faster migration through a porous environment, a process which depends on both motility and growth. We find that a trade-off between swimming speed and growth rate constrains the evolution of faster migration. Evolving faster migration in rich medium results in slow growth and fast swimming, while evolution in minimal medium results in fast growth and slow swimming. In each condition parallel genomic evolution drives adaptation through different mutations. We show that the trade-off is mediated by antagonistic pleiotropy through mutations that affect negative regulation. A model of the evolutionary process shows that the genetic capacity of an organism to vary traits can qualitatively depend on its environment, which in turn alters its evolutionary trajectory. DOI:http://dx.doi.org/10.7554/eLife.24669.001 In nature organisms face many challenges, and species adapt to their environment by changing heritable traits over the course of many generations. How organisms adapt is often limited by trade-offs, in which improving one trait can only come at the expense of another. In the laboratory, scientists use well-controlled environments to study how populations adapt to specific challenges without interference from their natural habitat. Most experiments, however, only look at simple challenges and do not take into account that organisms in the wild face many pressures at the same time. Fraebel et al. wanted to know what happens when an organism’s performance depends on two traits that are restricted by a trade-off. The experiments used populations of the bacterium Escherichia coli, which can go through hundreds of generations in a week, providing ample opportunity to study mutations and their impact on heritable traits. Through a combination of mathematical modeling and experiments, Fraebel et al. found that the environment is crucial for determining how bacteria adapt when their swimming speed and population growth rate are restricted by a trade-off. When nutrients are plentiful, E. coli populations evolve to spread faster by swimming more quickly despite growing more slowly. Yet, if nutrients are scarcer, the bacteria evolve to spread faster by growing more quickly despite swimming more slowly. In each scenario, the experiments identified single mutations that changed both swimming speed and growth rate by modifying regulatory activity in the cell. A better understanding of how an organism’s genetic architecture, its environment and trade-offs are connected may help identify the traits that are most easily changed by mutations. The ultimate goal would be to be able to predict evolutionary responses to complex selection pressures. DOI:http://dx.doi.org/10.7554/eLife.24669.002
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Affiliation(s)
- David T Fraebel
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, United States.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Harry Mickalide
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, United States.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Diane Schnitkey
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, United States.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Jason Merritt
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, United States.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Thomas E Kuhlman
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, United States.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States.,Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Seppe Kuehn
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, United States.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States.,Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, United States
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25
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Yang X, Sha K, Xu G, Tian H, Wang X, Chen S, Wang Y, Li J, Chen J, Huang N. Subinhibitory Concentrations of Allicin Decrease Uropathogenic Escherichia coli (UPEC) Biofilm Formation, Adhesion Ability, and Swimming Motility. Int J Mol Sci 2016; 17:ijms17070979. [PMID: 27367677 PMCID: PMC4964365 DOI: 10.3390/ijms17070979] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 06/08/2016] [Accepted: 06/15/2016] [Indexed: 11/16/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) biofilm formation enables the organism to avoid the host immune system, resist antibiotics, and provide a reservoir for persistent infection. Once the biofilm is established, eradication of the infection becomes difficult. Therefore, strategies against UPEC biofilm are urgently required. In this study, we investigated the effect of allicin, isolated from garlic essential oil, on UPEC CFT073 and J96 biofilm formation and dispersal, along with its effect on UPEC adhesion ability and swimming motility. Sub-inhibitory concentrations (sub-MICs) of allicin decreased UPEC biofilm formation and affected its architecture. Allicin was also capable of dispersing biofilm. Furthermore, allicin decreased the bacterial adhesion ability and swimming motility, which are important for biofilm formation. Real-time quantitative polymerase chain reaction (RT-qPCR) revealed that allicin decreased the expression of UPEC type 1 fimbriae adhesin gene fimH. Docking studies suggested that allicin was located within the binding pocket of heptyl α-d-mannopyrannoside in FimH and formed hydrogen bonds with Phe1 and Asn135. In addition, allicin decreased the expression of the two-component regulatory systems (TCSs) cognate response regulator gene uvrY and increased the expression of the RNA binding global regulatory protein gene csrA of UPEC CFT073, which is associated with UPEC biofilm. The findings suggest that sub-MICs of allicin are capable of affecting UPEC biofilm formation and dispersal, and decreasing UPEC adhesion ability and swimming motility.
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Affiliation(s)
- Xiaolong Yang
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Kaihui Sha
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Guangya Xu
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Hanwen Tian
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Xiaoying Wang
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Shanze Chen
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Yi Wang
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Jingyu Li
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Junli Chen
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
| | - Ning Huang
- Research Unit of Infection and Immunity, Department of Pathophysiology, West China School of Preclinical & Forensic Medicine, Sichuan University, Chengdu 610000, Sichuan, China.
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26
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Pressler K, Vorkapic D, Lichtenegger S, Malli G, Barilich BP, Cakar F, Zingl FG, Reidl J, Schild S. AAA+ proteases and their role in distinct stages along the Vibrio cholerae lifecycle. Int J Med Microbiol 2016; 306:452-62. [PMID: 27345492 DOI: 10.1016/j.ijmm.2016.05.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/09/2016] [Accepted: 05/24/2016] [Indexed: 12/29/2022] Open
Abstract
The facultative human pathogen Vibrio cholerae has to adapt to different environmental conditions along its lifecycle by means of transcriptional, translational and post-translational regulation. This study provides a first comprehensive analysis regarding the contribution of the cytoplasmic AAA+ proteases Lon, ClpP and HslV to distinct features of V. cholerae behaviour, including biofilm formation, motility, cholera toxin expression and colonization fitness in the mouse model. While absence of HslV did not yield to any altered phenotype compared to wildtype, absence of Lon or ClpP resulted in significantly reduced colonization in vivo. In addition, a Δlon deletion mutant showed altered biofilm formation and increased motility, which could be correlated with higher expression of V. cholerae flagella gene class IV. Concordantly, we could show by immunoblot analysis, that Lon is the main protease responsible for proteolytic control of FliA, which is required for class IV flagella gene transcription, but also downregulates virulence gene expression. FliA becomes highly sensitive to proteolytic degradation in absence of its anti-sigma factor FlgM, a scenario reported to occur during mucosal penetration due to FlgM secretion through the broken flagellum. Our results confirm that the high stability of FliA in the absence of Lon results in less cholera toxin and toxin corgulated pilus production under virulence gene inducing conditions and in the presence of a damaged flagellum. Thus, the data presented herein provide a molecular explanation on how V. cholerae can achieve full expression of virulence genes during early stages of colonization, despite FliA getting liberated from the anti-sigma factor FlgM.
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Affiliation(s)
- Katharina Pressler
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Dina Vorkapic
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Sabine Lichtenegger
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Gerald Malli
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Benjamin P Barilich
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Fatih Cakar
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Franz G Zingl
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Joachim Reidl
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria.
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27
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Molière N, Hoßmann J, Schäfer H, Turgay K. Role of Hsp100/Clp Protease Complexes in Controlling the Regulation of Motility in Bacillus subtilis. Front Microbiol 2016; 7:315. [PMID: 27014237 PMCID: PMC4793158 DOI: 10.3389/fmicb.2016.00315] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/29/2016] [Indexed: 11/16/2022] Open
Abstract
The Hsp100/Clp protease complexes of Bacillus subtilis ClpXP and ClpCP are involved in the control of many interconnected developmental and stress response regulatory networks, including competence, redox stress response, and motility. Here we analyzed the role of regulatory proteolysis by ClpXP and ClpCP in motility development. We have demonstrated that ClpXP acts on the regulation of motility by controlling the levels of the oxidative and heat stress regulator Spx. We obtained evidence that upon oxidative stress Spx not only induces the thiol stress response, but also transiently represses the transcription of flagellar genes. Furthermore, we observed that in addition to the known impact of ClpCP via the ComK/FlgM-dependent pathway, ClpCP also affects flagellar gene expression via modulating the activity and levels of the global regulator DegU-P. This adds another layer to the intricate involvement of Clp mediated regulatory proteolysis in different gene expression programs, which may allow to integrate and coordinate different signals for a better-adjusted response to the changing environment of B. subtilis cells.
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Affiliation(s)
- Noël Molière
- Naturwissenschaftliche Fakultät, Institut für Mikrobiologie, Leibniz Universität HannoverHannover, Germany; Institut für Biologie-Mikrobiologie, Freie Universität BerlinBerlin, Germany
| | - Jörn Hoßmann
- Institut für Biologie-Mikrobiologie, Freie Universität Berlin Berlin, Germany
| | - Heinrich Schäfer
- Naturwissenschaftliche Fakultät, Institut für Mikrobiologie, Leibniz Universität Hannover Hannover, Germany
| | - Kürşad Turgay
- Naturwissenschaftliche Fakultät, Institut für Mikrobiologie, Leibniz Universität HannoverHannover, Germany; Institut für Biologie-Mikrobiologie, Freie Universität BerlinBerlin, Germany
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28
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Refined live attenuated Salmonella enterica serovar Typhimurium and Enteritidis vaccines mediate homologous and heterologous serogroup protection in mice. Infect Immun 2015; 83:4504-12. [PMID: 26351285 DOI: 10.1128/iai.00924-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/02/2015] [Indexed: 01/01/2023] Open
Abstract
Invasive nontyphoidal Salmonella (NTS) infections constitute a major health problem among infants and toddlers in sub-Saharan Africa; these infections also occur in infants and the elderly in developed countries. We genetically engineered a Salmonella enterica serovar Typhimurium strain of multilocus sequence type 313, the predominant genotype circulating in sub-Saharan Africa. We evaluated the capacities of S. Typhimurium and Salmonella enterica serovar Enteritidis ΔguaBA ΔclpX live oral vaccines to protect mice against a highly lethal challenge dose of the homologous serovar and determined protection against other group B and D serovars circulating in sub-Saharan Africa. The vaccines S. Typhimurium CVD 1931 and S. Enteritidis CVD 1944 were immunogenic and protected BALB/c mice against 10,000 50% lethal doses (LD50) of S. Typhimurium or S. Enteritidis, respectively. S. Typhimurium CVD 1931 protected mice against the group B serovar Salmonella enterica serovar Stanleyville (91% vaccine efficacy), and S. Enteritidis CVD 1944 protected mice against the group D serovar Salmonella enterica serovar Dublin (85% vaccine efficacy). High rates of survival were observed when mice were infected 12 weeks postimmunization, indicating that the vaccines elicited long-lived protective immunity. Whereas CVD 1931 did not protect against S. Enteritidis R11, CVD 1944 did mediate protection against S. Typhimurium D65 (81% efficacy). These findings suggest that a bivalent (S. Typhimurium and S. Enteritidis) vaccine would provide broad protection against the majority of invasive NTS infections in sub-Saharan Africa.
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29
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Tennant SM, Levine MM. Live attenuated vaccines for invasive Salmonella infections. Vaccine 2015; 33 Suppl 3:C36-41. [PMID: 25902362 PMCID: PMC4469493 DOI: 10.1016/j.vaccine.2015.04.029] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/06/2015] [Accepted: 04/08/2015] [Indexed: 02/04/2023]
Abstract
Salmonella enterica serovar Typhi produces significant morbidity and mortality worldwide despite the fact that there are licensed Salmonella Typhi vaccines available. This is primarily due to the fact that these vaccines are not used in the countries that most need them. There is growing recognition that an effective invasive Salmonella vaccine formulation must also prevent infection due to other Salmonella serovars. We anticipate that a multivalent vaccine that targets the following serovars will be needed to control invasive Salmonella infections worldwide: Salmonella Typhi, Salmonella Paratyphi A, Salmonella Paratyphi B (currently uncommon but may become dominant again), Salmonella Typhimurium, Salmonella Enteritidis and Salmonella Choleraesuis (as well as other Group C Salmonella). Live attenuated vaccines are an attractive vaccine formulation for use in developing as well as developed countries. Here, we describe the methods of attenuation that have been used to date to create live attenuated Salmonella vaccines and provide an update on the progress that has been made on these vaccines.
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Affiliation(s)
- Sharon M Tennant
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Myron M Levine
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA.
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30
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Flagellin Is Required for Host Cell Invasion and Normal Salmonella Pathogenicity Island 1 Expression by Salmonella enterica Serovar Paratyphi A. Infect Immun 2015; 83:3355-68. [PMID: 26056383 DOI: 10.1128/iai.00468-15] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/03/2015] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Paratyphi A is a human-specific serovar that, together with Salmonella enterica serovar Typhi and Salmonella enterica serovar Sendai, causes enteric fever. Unlike the nontyphoidal Salmonella enterica serovar Typhimurium, the genomes of S. Typhi and S. Paratyphi A are characterized by inactivation of multiple genes, including in the flagellum-chemotaxis pathway. Here, we explored the motility phenotype of S. Paratyphi A and the role of flagellin in key virulence-associated phenotypes. Motility studies established that the human-adapted typhoidal S. Typhi, S. Paratyphi A, and S. Sendai are all noticeably less motile than S. Typhimurium, and comparative transcriptome sequencing (RNA-Seq) showed that in S. Paratyphi A, the entire motility-chemotaxis regulon is expressed at significantly lowers levels than in S. Typhimurium. Nevertheless, S. Paratyphi A, like S. Typhimurium, requires a functional flagellum for epithelial cell invasion and macrophage uptake, probably in a motility-independent mechanism. In contrast, flagella were found to be dispensable for host cell adhesion. Moreover, we demonstrate that in S. Paratyphi A, but not in S. Typhimurium, the lack of flagellin results in increased transcription of the flagellar and the Salmonella pathogenicity island 1 (SPI-1) regulons in a FliZ-dependent manner and in oversecretion of SPI-1 effectors via type three secretion system 1. Collectively, these results suggest a novel regulatory linkage between flagellin and SPI-1 in S. Paratyphi A that does not occur in S. Typhimurium and demonstrate curious distinctions in motility and the expression of the flagellum-chemotaxis regulon between these clinically relevant pathogens.
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31
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Ramachandran G, Perkins DJ, Schmidlein PJ, Tulapurkar ME, Tennant SM. Invasive Salmonella Typhimurium ST313 with naturally attenuated flagellin elicits reduced inflammation and replicates within macrophages. PLoS Negl Trop Dis 2015; 9:e3394. [PMID: 25569606 PMCID: PMC4287482 DOI: 10.1371/journal.pntd.0003394] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 11/04/2014] [Indexed: 01/19/2023] Open
Abstract
Invasive non-typhoidal Salmonella (iNTS) are an important cause of septicemia in children under the age of five years in sub-Saharan Africa. A novel genotype of Salmonella enterica subsp. enterica serovar Typhimurium (multi-locus sequence type [ST] 313) circulating in this geographic region is genetically different to from S. Typhimurium ST19 strains that are common throughout the rest of the world. S. Typhimurium ST313 strains have acquired pseudogenes and genetic deletions and appear to be evolving to become more like the typhoidal serovars S. Typhi and S. Paratyphi A. Epidemiological and clinical data show that S. Typhimurium ST313 strains are clinically associated with invasive systemic disease (bacteremia, septicemia, meningitis) rather than with gastroenteritis. The current work summarizes investigations of the broad hypothesis that S. Typhimurium ST313 isolates from Mali, West Africa, will behave differently from ST19 isolates in various in vitro assays. Here, we show that strains of the ST313 genotype are phagocytosed more efficiently and are highly resistant to killing by macrophage cell lines and primary mouse and human macrophages compared to ST19 strains. S. Typhimurium ST313 strains survived and replicated within different macrophages. Infection of macrophages with S. Typhimurium ST19 strains resulted in increased apoptosis and higher production of proinflammatory cytokines, as measured by gene expression and protein production, compared to S. Typhimurium ST313 strains. This difference in proinflammatory cytokine production and cell death between S. Typhimurium ST19 and ST313 strains could be explained, in part, by an increased production of flagellin by ST19 strains. These observations provide further evidence that S. Typhimurium ST313 strains are phenotypically different to ST19 strains and instead share similar pathogenic characteristics with typhoidal Salmonella serovars.
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Affiliation(s)
- Girish Ramachandran
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Darren J. Perkins
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Patrick J. Schmidlein
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Mohan E. Tulapurkar
- Division of Pulmonary and Critical Care, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Sharon M. Tennant
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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32
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Erhardt M, Mertens ME, Fabiani FD, Hughes KT. ATPase-independent type-III protein secretion in Salmonella enterica. PLoS Genet 2014; 10:e1004800. [PMID: 25393010 PMCID: PMC4230889 DOI: 10.1371/journal.pgen.1004800] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 10/02/2014] [Indexed: 01/06/2023] Open
Abstract
Type-III protein secretion systems are utilized by gram-negative pathogens to secrete building blocks of the bacterial flagellum, virulence effectors from the cytoplasm into host cells, and structural subunits of the needle complex. The flagellar type-III secretion apparatus utilizes both the energy of the proton motive force and ATP hydrolysis to energize substrate unfolding and translocation. We report formation of functional flagella in the absence of type-III ATPase activity by mutations that increased the proton motive force and flagellar substrate levels. We additionally show that increased proton motive force bypassed the requirement of the Salmonella pathogenicity island 1 virulence-associated type-III ATPase for secretion. Our data support a role for type-III ATPases in enhancing secretion efficiency under limited secretion substrate concentrations and reveal the dispensability of ATPase activity in the type-III protein export process.
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Affiliation(s)
- Marc Erhardt
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
- * E-mail:
| | - Max E. Mertens
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Florian D. Fabiani
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Kelly T. Hughes
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
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Sato Y, Takaya A, Mouslim C, Hughes KT, Yamamoto T. FliT selectively enhances proteolysis of FlhC subunit in FlhD4C2 complex by an ATP-dependent protease, ClpXP. J Biol Chem 2014; 289:33001-11. [PMID: 25278020 DOI: 10.1074/jbc.m114.593749] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously reported that the ClpXP ATP-dependent protease specifically recognizes and degrades the flagellar master transcriptional activator complex, FlhD4C2, to negatively control flagellar biogenesis. The flagellum-related protein, FliT, is also a negative regulator of flagellar regulon by inhibiting the binding of FlhD4C2 to the promoter DNA. We have found a novel pathway of FliT inhibition of FlhD4C2 activity connected to ClpXP proteolysis. An in vitro degradation assay using purified proteins shows that FliT selectively increases ClpXP proteolysis of the FlhC subunit in the FlhD4C2 complex. FliT behaves specifically to ClpXP-dependent proteolysis of FlhC. An in vitro interaction assay detects the ternary complex of FliT-FlhD4C2-ClpX. FliT promotes the affinity of ClpX against FlhD4C2 complex, whereas FliT does not directly interact with ClpX. Thus, FliT interacts with the FlhC in FlhD4C2 complex and increases the presentation of the FlhC recognition region to ClpX. The DNA-bound form of FlhD4C2 complex is resistant to ClpXP proteolysis. We suggest that the role of FliT in negatively controlling the flagellar gene expression involves increasing free molecules of FlhD4C2 sensitive to ClpXP proteolysis by inhibiting the binding to the promoter DNA as well as enhancing the selective proteolysis of FlhC subunit by ClpXP.
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Affiliation(s)
- Yoshiharu Sato
- From the Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675 Japan and
| | - Akiko Takaya
- From the Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675 Japan and
| | - Chakib Mouslim
- the Department of Biology, University of Utah, Salt Lake City, Utah 84112
| | - Kelly T Hughes
- the Department of Biology, University of Utah, Salt Lake City, Utah 84112
| | - Tomoko Yamamoto
- From the Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675 Japan and
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Assembling flagella in Salmonella mutant strains producing a type III export apparatus without FliO. J Bacteriol 2014; 196:4001-11. [PMID: 25201947 DOI: 10.1128/jb.02184-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type III export apparatus of the Salmonella flagellum consists of six transmembrane proteins (FlhA, FlhB, FliO, FliP, FliQ, and FliR) and three soluble proteins (FliH, FliI, and FliJ). Deletion of the fliO gene creates a mutant strain that is poorly motile; however, suppressor mutations in the fliP gene can partially rescue motility. To further understand the mechanism of suppression of a fliO deletion mutation, we isolated new suppressor mutant strains with partially rescued motility. Whole-genome sequence analysis of these strains found a missense mutation that localized to the clpP gene [clpP(V20F)], which encodes the ClpP subunit of the ClpXP protease, and a synonymous mutation that localized to the fliA gene [fliA(+36T→C)], which encodes the flagellar sigma factor, σ(28). Combining these suppressor mutations with mutations in the fliP gene additively rescued motility and biosynthesis of the flagella in fliO deletion mutant strains. Motility was also rescued by an flgM deletion mutation or by plasmids carrying either the flhDC or fliA gene. The fliA(+36T→C) mutation increased mRNA translation of a fliA'-lacZ gene fusion, and immunoblot analysis revealed that the mutation increased levels of σ(28). Quantitative real-time reverse transcriptase PCR showed that either the clpP(V20F) or fliA(+36T→C) mutation rescued expression of class 3 flagellar and chemotaxis genes; still, the suppressor mutations in the fliP gene had a greater effect on bypassing the loss of fliO function. This suggests that the function of FliO is closely associated with regulation of FliP during assembly of the flagellum.
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Singer HM, Erhardt M, Hughes KT. Comparative analysis of the secretion capability of early and late flagellar type III secretion substrates. Mol Microbiol 2014; 93:505-20. [PMID: 24946091 DOI: 10.1111/mmi.12675] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2014] [Indexed: 11/28/2022]
Abstract
A remarkable feature of the flagellar-specific type III secretion system (T3SS) is the selective recognition of a few substrate proteins among the many thousand cytoplasmic proteins. Secretion substrates are divided into two specificity classes: early substrates secreted for hook-basal body (HBB) construction and late substrates secreted after HBB completion. Secretion was reported to require a disordered N-terminal secretion signal, mRNA secretion signals within the 5'-untranslated region (5'-UTR) and for late substrates, piloting proteins known as the T3S chaperones. Here, we utilized translational β-lactamase fusions to probe the secretion efficacy of the N-terminal secretion signal of fourteen secreted flagellar substrates in Salmonella enterica. We observed a surprising variety in secretion capability between flagellar proteins of the same secretory class. The peptide secretion signals of the early-type substrates FlgD, FlgF, FlgE and the late-type substrate FlgL were analysed in detail. Analysing the role of the 5'-UTR in secretion of flgB and flgE revealed that the native 5'-UTR substantially enhanced protein translation and secretion. Based on our data, we propose a multicomponent signal that drives secretion via the flagellar T3SS. Both mRNA and peptide signals are recognized by the export apparatus and together with substrate-specific chaperones allowing for targeted secretion of flagellar substrates.
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Affiliation(s)
- Hanna M Singer
- Microbiologie, Département de Médecine, Université de Fribourg, Fribourg, Switzerland
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Mouslim C, Hughes KT. The effect of cell growth phase on the regulatory cross-talk between flagellar and Spi1 virulence gene expression. PLoS Pathog 2014; 10:e1003987. [PMID: 24603858 PMCID: PMC3946378 DOI: 10.1371/journal.ppat.1003987] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 01/25/2014] [Indexed: 12/22/2022] Open
Abstract
The flagellar regulon controls Salmonella biofilm formation, virulence gene expression and the production of the major surface antigen present on the cell surface: flagellin. At the top of a flagellar regulatory hierarchy is the master operon, flhDC, which encodes the FlhD₄C₂ transcriptional complex required for the expression of flagellar, chemotaxis and Salmonella pathogenicity island 1 (Spi1) genes. Of six potential transcriptional start-sites within the flhDC promoter region, only two, P1(flhDC) and P5(flhDC), were functional in a wild-type background, while P6(flhDC) was functional in the absence of CRP. These promoters are transcribed differentially to control either flagellar or Spi1 virulent gene expression at different stages of cell growth. Transcription from P1(flhDC) initiates flagellar assembly and a negative autoregulatory loop through FlhD₄C₂-dependent transcription of the rflM gene, which encodes a repressor of flhDC transcription. Transcription from P1(flhDC) also initiates transcription of the Spi1 regulatory gene, hilD, whose product, in addition to activating Spi1 genes, also activates transcription of the flhDC P5 promoter later in the cell growth phase. The regulators of flhDC transcription (RcsB, LrhA, RflM, HilD, SlyA and RtsB) also exert their control at different stages of the cell growth phase and are also subjected to cell growth phase control. This dynamic of flhDC transcription separates the roles of FlhD₄C₂ transcriptional activation into an early cell growth phase role for flagellar production from a late cell growth phase role in virulence gene expression.
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Affiliation(s)
- Chakib Mouslim
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Kelly T. Hughes
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
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Ricci V, Blair JMA, Piddock LJV. RamA, which controls expression of the MDR efflux pump AcrAB-TolC, is regulated by the Lon protease. J Antimicrob Chemother 2013; 69:643-50. [PMID: 24169580 PMCID: PMC3922155 DOI: 10.1093/jac/dkt432] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES RamA regulates the AcrAB-TolC multidrug efflux system. Using Salmonella Typhimurium, we investigated the stability of RamA and its impact on antibiotic resistance. METHODS To detect RamA, we introduced ramA::3XFLAG::aph into plasmid pACYC184 and transformed this into Salmonella Typhimurium SL1344ramA::cat and lon::aph mutants. An N-terminus-deleted mutant [pACYC184ramA(Δ2-21)::3XFLAG::aph] in which the first 20 amino acids of RamA were deleted was also constructed. To determine the abundance and half-life of FLAG-tagged RamA, we induced RamA with chlorpromazine (50 mg/L) and carried out western blotting using anti-FLAG antibody. Susceptibility to antibiotics and phenotypic characterization of the lon mutant was also carried out. RESULTS We show that on removal of chlorpromazine, a known inducer of ramA, the abundance of RamA decreased to pre-induced levels. However, in cells lacking functional Lon, we found that the RamA protein was not degraded. We also demonstrated that the 21 amino acid residues of the RamA N-terminus are required for recognition by the Lon protease. Antimicrobial susceptibility and phenotypic tests showed that the lon mutant was more susceptible to fluoroquinolone antibiotics, was filamentous when observed by microscopy and grew poorly, but showed no difference in motility or the ability to form a biofilm. There was also no difference in the ability of the lon mutant to invade human intestinal cells (INT-407). CONCLUSIONS In summary, we show that the ATP-dependent Lon protease plays an important role in regulating the expression of RamA and therefore multidrug resistance via AcrAB-TolC in Salmonella Typhimurium.
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Affiliation(s)
- Vito Ricci
- Antimicrobials Research Group, School of Immunity and Infection and Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
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Innate immune detection of flagellin positively and negatively regulates salmonella infection. PLoS One 2013; 8:e72047. [PMID: 23977202 PMCID: PMC3747147 DOI: 10.1371/journal.pone.0072047] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 07/06/2013] [Indexed: 11/19/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is a flagellated bacterium and one of the leading causes of gastroenteritis in humans. Bacterial flagellin is required for motility and also a prime target of the innate immune system. Innate immune recognition of flagellin is mediated by at least two independent pathways, TLR5 and Naip5-Naip6/NlrC4/Caspase-1. The functional significance of each of the two independent flagellin recognition systems for host defense against wild type Salmonella infection is complex, and innate immune detection of flagellin contributes to both protection and susceptibility. We hypothesized that efficient modulation of flagellin expression in vivo permits Salmonella to evade innate immune detection and limit the functional role of flagellin-specific host innate defenses. To test this hypothesis, we used Salmonella deficient in the anti-sigma factor flgM, which overproduce flagella and are attenuated in vivo. In this study we demonstrate that flagellin recognition by the innate immune system is responsible for the attenuation of flgM− S. Typhimurium, and dissect the contribution of each flagellin recognition pathway to bacterial clearance and inflammation. We demonstrate that caspase-1 controls mucosal and systemic infection of flgM− S. Typhimurium, and also limits intestinal inflammation and injury. In contrast, TLR5 paradoxically promotes bacterial colonization in the cecum and systemic infection, but attenuates intestinal inflammation. Our results indicate that Salmonella evasion of caspase-1 dependent flagellin recognition is critical for establishing infection and that evasion of TLR5 and caspase-1 dependent flagellin recognition helps Salmonella induce intestinal inflammation and establish a niche in the inflamed gut.
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ClpP deletion causes attenuation of Salmonella Typhimurium virulence through mis-regulation of RpoS and indirect control of CsrA and the SPI genes. Microbiology (Reading) 2013; 159:1497-1509. [DOI: 10.1099/mic.0.065797-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated with the proteases either encoded within the same polypeptide or on separate subunits. In contrast, substrate recognition by extracellular proteases is less selective and therefore these enzymes are generally expressed as zymogens to prevent premature proteolytic activity that would be detrimental to the cell. These extracellular proteases are activated in complex cascades involving auto-processing and proteolytic maturation. Thus, proteolysis has been adopted by bacterial pathogens at multiple levels to ensure the success of the pathogen in contact with the human host.
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Affiliation(s)
- Dorte Frees
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4, Frederiksberg, C 1870, Denmark
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Yang X, Thornburg T, Suo Z, Jun S, Robison A, Li J, Lim T, Cao L, Hoyt T, Avci R, Pascual DW. Flagella overexpression attenuates Salmonella pathogenesis. PLoS One 2012; 7:e46828. [PMID: 23056473 PMCID: PMC3463563 DOI: 10.1371/journal.pone.0046828] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 09/05/2012] [Indexed: 11/18/2022] Open
Abstract
Flagella are cell surface appendages involved in a number of bacterial behaviors, such as motility, biofilm formation, and chemotaxis. Despite these important functions, flagella can pose a liability to a bacterium when serving as potent immunogens resulting in the stimulation of the innate and adaptive immune systems. Previous work showing appendage overexpression, referred to as attenuating gene expression (AGE), was found to enfeeble wild-type Salmonella. Thus, this approach was adapted to discern whether flagella overexpression could induce similar attenuation. To test its feasibility, flagellar filament subunit FliC and flagellar regulon master regulator FlhDC were overexpressed in Salmonella enterica serovar Typhimurium wild-type strain H71. The results show that the expression of either FliC or FlhDC alone, and co-expression of the two, significantly attenuates Salmonella. The flagellated bacilli were unable to replicate within macrophages and thus were not lethal to mice. In-depth investigation suggests that flagellum-mediated AGE was due to the disruptive effects of flagella on the bacterial membrane, resulting in heightened susceptibilities to hydrogen peroxide and bile. Furthermore, flagellum-attenuated Salmonella elicited elevated immune responses to Salmonella presumably via FliC's adjuvant effect and conferred robust protection against wild-type Salmonella challenge.
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Affiliation(s)
- Xinghong Yang
- Department of Immunology & Infectious Diseases, Montana State University, Bozeman, Montana, United States of America.
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Li B, Li N, Wang F, Guo L, Huang Y, Liu X, Wei T, Zhu D, Liu C, Pan H, Xu S, Wang HW, Gu L. Structural insight of a concentration-dependent mechanism by which YdiV inhibits Escherichia coli flagellum biogenesis and motility. Nucleic Acids Res 2012; 40:11073-85. [PMID: 23002140 PMCID: PMC3510510 DOI: 10.1093/nar/gks869] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
YdiV is a negative regulator of cell motility. It interacts with FlhD4C2 complex, a product of flagellar master operon, which works as the transcription activator of all other flagellar operons. Here, we report the crystal structures of YdiV and YdiV2–FlhD2 complex at 1.9 Å and 2.9 Å resolutions, respectively. Interestingly, YdiV formed multiple types of complexes with FlhD4C2. YdiV1–FlhD4C2 and YdiV2–FlhD4C2 still bound to DNA, while YdiV3–FlhD4C2 and YdiV4–FlhD4C2 did not. DNA bound FlhD4C2 through wrapping around the FlhC subunit rather than the FlhD subunit. Structural analysis showed that only two peripheral FlhD subunits were accessible for YdiV binding, forming the YdiV2–FlhD4C2 complex without affecting the integrity of ring-like structure. YdiV2–FlhD2 structure and the negative staining electron microscopy reconstruction of YdiV4–FlhD4C2 suggested that the third and fourth YdiV molecule bound to the FlhD4C2 complex through squeezing into the ring-like structure of FlhD4C2 between the two internal D subunits. Consequently, the ring-like structure opened up, and the complex lost DNA-binding ability. Thus, YdiV inhibits FlhD4C2 only at relatively high concentrations.
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Affiliation(s)
- Bingqing Li
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
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Hung CC, Haines L, Altier C. The flagellar regulator fliT represses Salmonella pathogenicity island 1 through flhDC and fliZ. PLoS One 2012; 7:e34220. [PMID: 22479568 PMCID: PMC3313986 DOI: 10.1371/journal.pone.0034220] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 02/24/2012] [Indexed: 12/22/2022] Open
Abstract
Salmonella pathogenicity island 1 (SPI1), comprising a type III section system that translocates effector proteins into host cells, is essential for the enteric pathogen Salmonella to penetrate the intestinal epithelium and subsequently to cause disease. Using random transposon mutagenesis, we found that a Tn10 disruption in the flagellar fliDST operon induced SPI1 expression when the strain was grown under conditions designed to repress SPI1, by mimicking the environment of the large intestine through the use of the intestinal fatty acid butyrate. Our genetic studies showed that only fliT within this operon was required for this effect, and that exogenous over-expression of fliT alone significantly reduced the expression of SPI1 genes, including the invasion regulator hilA and the sipBCDA operon, encoding type III section system effector proteins, and Salmonella invasion of cultured epithelial cells. fliT has been known to inhibit the flagellar machinery through repression of the flagellar master regulator flhDC. We found that the repressive effect of fliT on invasion genes was completely abolished in the absence of flhDC or fliZ, the latter previously shown to induce SPI1, indicating that this regulatory pathway is required for invasion control by fliT. Although this flhDC-fliZ pathway was necessary for fliT to negatively control invasion genes, fliZ was not essential for the repressive effect of fliT on motility, placing fliT high in the regulatory cascade for both invasion and motility.
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Affiliation(s)
| | | | - Craig Altier
- Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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Takaya A, Erhardt M, Karata K, Winterberg K, Yamamoto T, Hughes KT. YdiV: a dual function protein that targets FlhDC for ClpXP-dependent degradation by promoting release of DNA-bound FlhDC complex. Mol Microbiol 2012; 83:1268-84. [PMID: 22380597 DOI: 10.1111/j.1365-2958.2012.08007.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
YdiV is an EAL-like protein that acts as a post-transcriptional, negative regulator of the flagellar master transcriptional activator complex, FlhD(4)C(2), in Salmonella enterica to couple flagellar gene expression to nutrient availability. Mutants defective in ClpXP protease no longer exhibit YdiV-dependent inhibition of FlhD(4)C(2)-dependent transcription under moderate YdiV expression conditions. ClpXP protease degrades FlhD(4)C(2), and this degradation is accelerated in the presence of YdiV. YdiV complexed with both free and DNA-bound FlhD(4)C(2); and stripped FlhD(4)C(2) from DNA. A L22H substitution in FlhD was isolated as insensitive to YdiV inhibition. The FlhD L22H substitution prevented the interaction of YdiV with free FlhD(4)C(2) and the ability of YdiV to release FlhD(4)C(2) bound to DNA. These results demonstrate that YdiV prevents FlhD(4)C(2)-dependent flagellar gene transcription and acts as a putative adaptor to target FlhD(4)C(2) for ClpXP-dependent proteolysis. Our results suggest that YdiV is an EAL-like protein that has evolved from a dicyclic-GMP phosphodiesterase into a dual-function regulatory protein that connects flagellar gene expression to nutrient starvation.
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Affiliation(s)
- Akiko Takaya
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675 Japan
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Yamamoto T. [Regulatory mechanisms for stress response and pathogenesis of facultative intracellular bacteria]. Nihon Saikingaku Zasshi 2012; 66:517-29. [PMID: 22214748 DOI: 10.3412/jsb.66.517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Tomoko Yamamoto
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana, Chuo-ku, Chiba 260-8675, Japan
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Regulation of phenotypic heterogeneity permits Salmonella evasion of the host caspase-1 inflammatory response. Proc Natl Acad Sci U S A 2011; 108:20742-7. [PMID: 22143773 DOI: 10.1073/pnas.1108963108] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sensing and adapting to the environment is one strategy by which bacteria attempt to maximize fitness in an unpredictable world; another is the stochastic generation of phenotypically distinct subgroups within a genetically clonal population. In culture, Salmonella Typhimurium populations are bistable for the expression of flagellin. We report that YdiV controls this expression pattern by preventing transcription of the sigma factor that recruits RNA polymerase to the flagellin promoter. Bistability ensues when the sigma factor is repressed in a subpopulation of cells, resulting in two phenotypes: flagellin expressors and flagellin nonexpressors. Although the ability to swim is presumably a critical survival trait, flagellin activates eukaryotic defense pathways, and Salmonella restrict the production of flagellin during systemic infection. Salmonella mutants lacking YdiV are unable to fully repress flagellin at systemic sites, rendering them vulnerable to caspase-1 mediated colonization restriction. Thus, a regulatory mechanism producing bistability also impacts Salmonella virulence.
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Abstract
In their stressful natural environments, bacteria often are in stationary phase and use their limited resources for maintenance and stress survival. Underlying this activity is the general stress response, which in Escherichia coli depends on the σS (RpoS) subunit of RNA polymerase. σS is closely related to the vegetative sigma factor σ70 (RpoD), and these two sigmas recognize similar but not identical promoter sequences. During the postexponential phase and entry into stationary phase, σS is induced by a fine-tuned combination of transcriptional, translational, and proteolytic control. In addition, regulatory "short-cuts" to high cellular σS levels, which mainly rely on the rapid inhibition of σS proteolysis, are triggered by sudden starvation for various nutrients and other stressful shift conditons. σS directly or indirectly activates more than 500 genes. Additional signal input is integrated by σS cooperating with various transcription factors in complex cascades and feedforward loops. Target gene products have stress-protective functions, redirect metabolism, affect cell envelope and cell shape, are involved in biofilm formation or pathogenesis, or can increased stationary phase and stress-induced mutagenesis. This review summarizes these diverse functions and the amazingly complex regulation of σS. At the molecular level, these processes are integrated with the partitioning of global transcription space by sigma factor competition for RNA polymerase core enzyme and signaling by nucleotide second messengers that include cAMP, (p)ppGpp, and c-di-GMP. Physiologically, σS is the key player in choosing between a lifestyle associated with postexponential growth based on nutrient scavenging and motility and a lifestyle focused on maintenance, strong stress resistance, and increased adhesiveness. Finally, research with other proteobacteria is beginning to reveal how evolution has further adapted function and regulation of σS to specific environmental niches.
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Gat O, Galen JE, Tennant S, Simon R, Blackwelder WC, Silverman DJ, Pasetti MF, Levine MM. Cell-associated flagella enhance the protection conferred by mucosally-administered attenuated Salmonella Paratyphi A vaccines. PLoS Negl Trop Dis 2011; 5:e1373. [PMID: 22069504 PMCID: PMC3206010 DOI: 10.1371/journal.pntd.0001373] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 09/08/2011] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Antibiotic-resistant Salmonella enterica serovar Paratyphi A, the agent of paratyphoid A fever, poses an emerging public health dilemma in endemic areas of Asia and among travelers, as there is no licensed vaccine. Integral to our efforts to develop a S. Paratyphi A vaccine, we addressed the role of flagella as a potential protective antigen by comparing cell-associated flagella with exported flagellin subunits expressed by attenuated strains. METHODOLOGY S. Paratyphi A strain ATCC 9150 was first deleted for the chromosomal guaBA locus, creating CVD 1901. Further chromosomal deletions in fliD (CVD 1901D) or flgK (CVD 1901K) were then engineered, resulting in the export of unpolymerized FliC, without impairing its overall expression. The virulence of the resulting isogenic strains was examined using a novel mouse LD(50) model to accommodate the human-host restricted S. Paratyphi A. The immunogenicity of the attenuated strains was then tested using a mouse intranasal model, followed by intraperitoneal challenge with wildtype ATCC 9150. RESULTS Mucosal (intranasal) immunization of mice with strain CVD 1901 expressing cell-associated flagella conferred superior protection (vaccine efficacy [VE], 90%) against a lethal intraperitoneal challenge, compared with the flagellin monomer-exporting mutants CVD 1901K (30% VE) or CVD 1901D (47% VE). The superior protection induced by CVD 1901 with its cell-attached flagella was associated with an increased IgG2a:IgG1 ratio of FliC-specific antibodies with enhanced opsonophagocytic capacity. CONCLUSIONS Our results clearly suggest that enhanced anti-FliC antibody-mediated clearance of S. Paratyphi A by phagocytic cells, induced by vaccines expressing cell-associated rather than exported FliC, might be contributing to the vaccine-induced protection from S. Paratyphi A challenge in vivo. We speculate that an excess of IgG1 anti-FliC antibodies induced by the exported FliC may compete with the IgG2a subtype and block binding to specific phagocyte Fc receptors that are critical for clearing an S. Paratyphi A infection.
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Affiliation(s)
- Orit Gat
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James E. Galen
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Sharon Tennant
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Raphael Simon
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - William C. Blackwelder
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - David J. Silverman
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Marcela F. Pasetti
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Myron M. Levine
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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Kitagawa R, Takaya A, Yamamoto T. Dual regulatory pathways of flagellar gene expression by ClpXP protease in enterohaemorrhagic Escherichia coli. MICROBIOLOGY-SGM 2011; 157:3094-3103. [PMID: 21903756 DOI: 10.1099/mic.0.051151-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In enterobacteria such as Escherichia coli and Salmonella species, flagellar biogenesis is strictly dependent upon the master regulator flhDC. Here, we demonstrate that in enterohaemorrhagic E. coli (EHEC), the flagellar regulon is controlled by ClpXP, a member of the ATP-dependent protease family, through two pathways: (i) post-translational control of the FlhD/FlhC master regulator and (ii) transcriptional control of the flhDC operon. Both FlhD and FlhC proteins accumulated markedly following ClpXP depletion, and their half-lives were significantly longer in the mutant cells, suggesting that ClpXP is responsible for degrading FlhD and FlhC proteins, leading to downregulation of flagellar expression. ClpXP was involved in regulating the transcription of the flhD promoter only when the cells had entered stationary phase in a culture medium that markedly induced expression of the locus of enterocyte effacement (LEE). Comparative analyses of transcription from the flhD promoter in EHEC cells with different genetic backgrounds suggested that the downregulation of flhDC expression by ClpXP is dependent on the LEE-encoded GrlR-GrlA system. We have also shown that the degradation of FlhD and FlhC by ClpXP is responsible for downregulating flagellar expression even when LEE expression is induced.
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Affiliation(s)
- Ryo Kitagawa
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Akiko Takaya
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Tomoko Yamamoto
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
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50
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Engineering and preclinical evaluation of attenuated nontyphoidal Salmonella strains serving as live oral vaccines and as reagent strains. Infect Immun 2011; 79:4175-85. [PMID: 21807911 DOI: 10.1128/iai.05278-11] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
While nontyphoidal Salmonella (NTS) has long been recognized as a cause of self-limited gastroenteritis, it is becoming increasingly evident that multiple-antibiotic-resistant strains are also emerging as important causes of invasive bacteremia and focal infections, resulting in hospitalizations and deaths. We have constructed attenuated Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis strains that can serve as live oral vaccines and as "reagent strains" for subunit vaccine production in a safe and economical manner. Prototype attenuated vaccine strains CVD 1921 and CVD 1941, derived from the invasive wild-type strains S. Typhimurium I77 and S. Enteritidis R11, respectively, were constructed by deleting guaBA, encoding guanine biosynthesis, and clpP, encoding a master protease regulator. The clpP mutation resulted in a hyperflagellation phenotype. An additional deletion in fliD yielded reagent strains CVD 1923 and CVD 1943, respectively, which export flagellin monomers. Oral 50% lethal dose (LD₅₀) analyses showed that the NTS vaccine strains were all highly attenuated in mice. Oral immunization with CVD 1921 or CVD 1923 protected mice against lethal challenge with wild-type S. Typhimurium I77. Immunization with CVD 1941 but not CVD 1943 protected mice against lethal infection with S. Enteritidis R11. Immune responses induced by these strains included high levels of serum IgG anti-lipopolysaccharide (LPS) and anti-flagellum antibodies, with titers increasing progressively during the immunization schedule. Since S. Typhimurium and S. Enteritidis are the most common NTS serovars associated with invasive disease, these findings can pave the way for development of a highly effective, broad-spectrum vaccine against invasive NTS.
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