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Degabriel M, Valeva S, Boisset S, Henry T. Pathogenicity and virulence of Francisella tularensis. Virulence 2023; 14:2274638. [PMID: 37941380 PMCID: PMC10653695 DOI: 10.1080/21505594.2023.2274638] [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: 05/16/2023] [Accepted: 10/18/2023] [Indexed: 11/10/2023] Open
Abstract
Tularaemia is a zoonotic disease caused by the Gram-negative bacterium, Francisella tularensis. Depending on its entry route into the organism, F. tularensis causes different diseases, ranging from life-threatening pneumonia to less severe ulceroglandular tularaemia. Various strains with different geographical distributions exhibit different levels of virulence. F. tularensis is an intracellular bacterium that replicates primarily in the cytosol of the phagocytes. The main virulence attribute of F. tularensis is the type 6 secretion system (T6SS) and its effectors that promote escape from the phagosome. In addition, F. tularensis has evolved a peculiar envelope that allows it to escape detection by the immune system. In this review, we cover tularaemia, different Francisella strains, and their pathogenicity. We particularly emphasize the intracellular life cycle, associated virulence factors, and metabolic adaptations. Finally, we present how F. tularensis largely escapes immune detection to be one of the most infectious and lethal bacterial pathogens.
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Affiliation(s)
- Manon Degabriel
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Univ Lyon, LYON, France
| | - Stanimira Valeva
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Univ Lyon, LYON, France
| | - Sandrine Boisset
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Univ Lyon, LYON, France
- Univ. Grenoble Alpes, CHU Grenoble Alpes, CNRS, CEA, UMR5075, Institut de Biologie Structurale, Grenoble, France
| | - Thomas Henry
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Univ Lyon, LYON, France
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Marakasova E, Ii A, Nelson KT, van Hoek ML. Proteome Wide Profiling of N-ε-Lysine Acetylation Reveals a Novel Mechanism of Regulation of the Chitinase Activity in Francisella novicida. J Proteome Res 2020; 19:1409-1422. [PMID: 32056440 DOI: 10.1021/acs.jproteome.9b00512] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Francisella tularensis is a Gram-negative bacterium that causes the zoonotic disease tularemia. The historical development of tularemia as a biological weapon has led to it being characterized by the CDC as a category A biothreat agent. Neither posttranslational modification (PTM) of proteins, in particular lysine acetylation, in Francisella nor its subsequent regulation of the protein activity has been well studied. In this work, we analyze N-ε-lysine acetylation of the F. tularensis ssp. novicida proteome by mass spectrometry for the first time. To create a comprehensive acetylation profile, we enriched protein acetylation using two approaches: (1) the addition of glucose or acetate into the culture medium and (2) direct chemical acetylation of N-ε-lysines with acetyl phosphate. We discovered 280 acetylated proteins with 1178 acetylation sites in the F. tularensis ssp. novicida strain U112. Lysine acetylation is an important PTM that regulates multiple cellular processes in bacteria, including metabolism, transcription, translation, stress response, and protein folding. We discovered that Francisella chitinases A and B are acetylated naturally and when chemically induced by acetyl phosphate. Moreover, chemical overacetylation of chitinases results in silencing of the enzymatic activity. Our findings suggest a novel mechanism of posttranslational regulation of the chitinase activity and that acetylation may play a role in Francisella's regulation of the protein activity.
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Affiliation(s)
- Ekaterina Marakasova
- School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, Virginia 20110, United States
| | - Alexandra Ii
- School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, Virginia 20110, United States
| | - Kristina T Nelson
- Chemical and Proteomic Mass Spectrometry Core Facility, Virginia Commonwealth University, 1001 W. Main Street, Richmond, Virginia 23284, United States
| | - Monique L van Hoek
- School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, Virginia 20110, United States
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Abstract
Over the past decade the number and variety of protein post-translational modifications that have been detected and characterized in bacteria have rapidly increased. Most post-translational protein modifications occur in a relatively low number of bacterial proteins in comparison with eukaryotic proteins, and most of the modified proteins carry low, substoichiometric levels of modification; therefore, their structural and functional analysis is particularly challenging. The number of modifying enzymes differs greatly among bacterial species, and the extent of the modified proteome strongly depends on environmental conditions. Nevertheless, evidence is rapidly accumulating that protein post-translational modifications have vital roles in various cellular processes such as protein synthesis and turnover, nitrogen metabolism, the cell cycle, dormancy, sporulation, spore germination, persistence and virulence. Further research of protein post-translational modifications will fill current gaps in the understanding of bacterial physiology and open new avenues for treatment of infectious diseases.
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Shimizu T, Otonari S, Suzuki J, Uda A, Watanabe K, Watarai M. Expression of Francisella pathogenicity island protein intracellular growth locus E (IglE) in mammalian cells is involved in intracellular trafficking, possibly through microtubule organizing center. Microbiologyopen 2018; 8:e00684. [PMID: 29978561 PMCID: PMC6460260 DOI: 10.1002/mbo3.684] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/07/2018] [Accepted: 06/09/2018] [Indexed: 01/01/2023] Open
Abstract
Francisella tularensis is the causative agent of the infectious disease tularemia and is designated a category A bioterrorism agent. The type VI secretion system encoded by the Francisella pathogenicity island (FPI) is necessary for intracellular growth; however, the functions of FPI proteins are largely unknown. In this study, we found that the FPI protein intracellular growth locus E (IglE) showed a unique localization pattern compared to other FPI proteins. Deleting iglE from Francisella tularensis subsp. novicida (F. novicida) decreased intracellular growth. Immunoprecipitation and pull‐down assays revealed that IglE was associated with β‐tubulin. Additionally, GFP‐fused IglE colocalized with microtubule organizing centers (MTOCs) in 293T cells. The iglE deletion mutant was transferred with dynein toward MTOCs and packed into lysosome‐localizing areas. Conversely, the wild‐type F. novicida exhibited intracellular growth distant from MTOCs. In addition, IglE expressed in 293T cells colocalized with dynein. These results suggest that IglE helps to prevent dynein‐ and MTOC‐mediated intracellular trafficking in host cells to inhibit the transport of F. novicida toward lysosomes.
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Affiliation(s)
- Takashi Shimizu
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Shiho Otonari
- Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Jin Suzuki
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Akihiko Uda
- Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Japan
| | - Kenta Watanabe
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
| | - Masahisa Watarai
- The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.,Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan
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Clemens DL, Lee BY, Horwitz MA. The Francisella Type VI Secretion System. Front Cell Infect Microbiol 2018; 8:121. [PMID: 29740542 PMCID: PMC5924787 DOI: 10.3389/fcimb.2018.00121] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/03/2018] [Indexed: 12/27/2022] Open
Abstract
Francisella tularensisis subsp. tularensis is an intracellular bacterial pathogen and the causative agent of the life-threatening zoonotic disease tularemia. The Francisella Pathogenicity Island encodes a large secretion apparatus, known as a Type VI Secretion System (T6SS), which is essential for Francisella to escape from its phagosome and multiply within host macrophages and to cause disease in animals. The T6SS, found in one-quarter of Gram-negative bacteria including many highly pathogenic ones, is a recently discovered secretion system that is not yet fully understood. Nevertheless, there have been remarkable advances in our understanding of the structure, composition, and function of T6SSs of several bacteria in the past few years. The system operates like an inside-out headless contractile phage that is anchored to the bacterial membrane via a baseplate and membrane complex. The system injects effector molecules across the inner and outer bacterial membrane and into host prokaryotic or eukaryotic targets to kill, intoxicate, or in the case of Francisella, hijack the target cell. Recent advances include an atomic model of the contractile sheath, insights into the mechanics of sheath contraction, the composition of the baseplate and membrane complex, the process of assembly of the apparatus, and identification of numerous effector molecules and activities. While Francisella T6SS appears to be an outlier among T6SSs, with limited or no sequence homology with other systems, its structure and organization are strikingly similar to other systems. Nevertheless, we have only scratched the surface in uncovering the mysteries of the Francisella T6SS, and there are numerous questions that remain to be answered.
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Affiliation(s)
- Daniel L. Clemens
- Division of Infectious Diseases, Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | | | - Marcus A. Horwitz
- Division of Infectious Diseases, Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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Affiliation(s)
- Petra Spidlova
- a Department of Molecular Pathology and Biology , Faculty of Military Health Sciences, University of Defence , Hradec Kralove , Czech Republic
| | - Jiri Stulik
- a Department of Molecular Pathology and Biology , Faculty of Military Health Sciences, University of Defence , Hradec Kralove , Czech Republic
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Bröms JE, Meyer L, Sjöstedt A. A mutagenesis-based approach identifies amino acids in the N-terminal part of Francisella tularensis IglE that critically control Type VI system-mediated secretion. Virulence 2016; 8:821-847. [PMID: 27830989 PMCID: PMC5626337 DOI: 10.1080/21505594.2016.1258507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The Gram-negative bacterium Francisella tularensis is the etiological agent of the zoonotic disease tularemia. Its life cycle is characterized by an ability to survive within phagocytic cells through phagosomal escape and replication in the cytosol, ultimately causing inflammasome activation and host cell death. Required for these processes is the Francisella Pathogenicity Island (FPI), which encodes a Type VI secretion system (T6SS) that is active during intracellular infection. In this study, we analyzed the role of the FPI-component IglE, a lipoprotein which we previously have shown to be secreted in a T6SS-dependent manner. We demonstrate that in F. tularensis LVS, IglE is an outer membrane protein. Upon infection of J774 cells, an ΔiglE mutant failed to escape from phagosomes, and subsequently, to multiply and cause cytopathogenicity. Moreover, ΔiglE was unable to activate the inflammasome, to inhibit LPS-stimulated secretion of TNF-α, and showed marked attenuation in the mouse model. In F. novicida, IglE was required for in vitro secretion of IglC and VgrG. A mutagenesis-based approach involving frameshift mutations and alanine substitution mutations within the first ∼ 38 residues of IglE revealed that drastic changes in the sequence of the extreme N-terminus (residues 2-6) were well tolerated and, intriguingly, caused hyper-secretion of IglE during intracellular infection, while even subtle mutations further downstream lead to impaired protein function. Taken together, this study highlights the importance of IglE in F. tularensis pathogenicity, and the contribution of the N-terminus for all of the above mentioned processes.
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Affiliation(s)
- Jeanette E Bröms
- a Department of Clinical Microbiology , Clinical Bacteriology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University , Umeå , Sweden
| | - Lena Meyer
- a Department of Clinical Microbiology , Clinical Bacteriology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University , Umeå , Sweden
| | - Anders Sjöstedt
- a Department of Clinical Microbiology , Clinical Bacteriology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University , Umeå , Sweden
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Rowe HM, Huntley JF. From the Outside-In: The Francisella tularensis Envelope and Virulence. Front Cell Infect Microbiol 2015; 5:94. [PMID: 26779445 PMCID: PMC4688374 DOI: 10.3389/fcimb.2015.00094] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 12/07/2015] [Indexed: 12/20/2022] Open
Abstract
Francisella tularensis is a highly-infectious bacterium that causes the rapid, and often lethal disease, tularemia. Many studies have been performed to identify and characterize the virulence factors that F. tularensis uses to infect a wide variety of hosts and host cell types, evade immune defenses, and induce severe disease and death. This review focuses on the virulence factors that are present in the F. tularensis envelope, including capsule, LPS, outer membrane, periplasm, inner membrane, secretion systems, and various molecules in each of aforementioned sub-compartments. Whereas, no single bacterial molecule or molecular complex single-handedly controls F. tularensis virulence, we review here how diverse bacterial systems work in conjunction to subvert the immune system, attach to and invade host cells, alter phagosome/lysosome maturation pathways, replicate in host cells without being detected, inhibit apoptosis, and induce host cell death for bacterial release and infection of adjacent cells. Given that the F. tularensis envelope is the outermost layer of the bacterium, we highlight herein how many of these molecules directly interact with the host to promote infection and disease. These and future envelope studies are important to advance our collective understanding of F. tularensis virulence mechanisms and offer targets for future vaccine development efforts.
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Affiliation(s)
- Hannah M Rowe
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences Toledo, OH, USA
| | - Jason F Huntley
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences Toledo, OH, USA
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The Divergent Intracellular Lifestyle of Francisella tularensis in Evolutionarily Distinct Host Cells. PLoS Pathog 2015; 11:e1005208. [PMID: 26633893 PMCID: PMC4669081 DOI: 10.1371/journal.ppat.1005208] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Cunningham AL, Dang KM, Yu JJ, Guentzel MN, Heidner HW, Klose KE, Arulanandam BP. Enhancement of vaccine efficacy by expression of a TLR5 ligand in the defined live attenuated Francisella tularensis subsp. novicida strain U112ΔiglB::fljB. Vaccine 2014; 32:5234-40. [PMID: 25050972 DOI: 10.1016/j.vaccine.2014.07.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 06/11/2014] [Accepted: 07/09/2014] [Indexed: 01/13/2023]
Abstract
Oral vaccination with the defined live attenuated Francisella novicida vaccine strain U112ΔiglB has been demonstrated to induce protective immunity against pulmonary challenge with the highly human virulent Francisella tularensis strain SCHU S4. However, this vaccination regimen requires a booster dose in mice and Exhibits 50% protective efficacy in the Fischer 344 rat model. To enhance the efficacy of this vaccine strain, we engineered U112ΔiglB to express the Salmonella typhimurium FljB flagellin D1 domain, a TLR5 agonist. The U112ΔiglB::fljB strain was highly attenuated for intracellular macrophage replication, and although the FljB protein was expressed within the cytosol, it exhibited TLR5 activation in a TLR5-expressing HEK cell line. Additionally, infection of splenocytes and lymphocytes with U112ΔiglB::fljB induced significantly greater TNF-α production than infection with U112ΔiglB. Oral vaccination with U112ΔiglB::fljB also induced significantly greater protection than U112ΔiglB against pulmonary SCHU S4 challenge in rats. The enhanced protection was accompanied by higher IgG2a production and serum-mediated reduction of Francisella infectivity. Thus, the U112ΔiglB::fljB strain may serve as a potential vaccine candidate against pneumonic tularemia.
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Affiliation(s)
- Aimee L Cunningham
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States; Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, United States
| | - Kim Minh Dang
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Jieh-Juen Yu
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - M Neal Guentzel
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Hans W Heidner
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Karl E Klose
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Bernard P Arulanandam
- South Texas Center for Emerging Infectious Disease and the Center for Excellence in Infection Genomics, University of Texas at San Antonio, San Antonio, TX 78249, United States.
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