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Sato Y, Takita A, Suzue K, Hashimoto Y, Hiramoto S, Murakami M, Tomita H, Hirakawa H. TusDCB, a sulfur transferase complex involved in tRNA modification, contributes to UPEC pathogenicity. Sci Rep 2024; 14:8978. [PMID: 38637685 PMCID: PMC11026471 DOI: 10.1038/s41598-024-59614-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 04/12/2024] [Indexed: 04/20/2024] Open
Abstract
tRNA modifications play a crucial role in ensuring accurate codon recognition and optimizing translation levels. While the significance of these modifications in eukaryotic cells for maintaining cellular homeostasis and physiological functions is well-established, their physiological roles in bacterial cells, particularly in pathogenesis, remain relatively unexplored. The TusDCB protein complex, conserved in γ-proteobacteria like Escherichia coli, is involved in sulfur modification of specific tRNAs. This study focused on the role of TusDCB in the virulence of uropathogenic E. coli (UPEC), a bacterium causing urinary tract infections. The findings indicate that TusDCB is essential for optimal production of UPEC's virulence factors, including type 1 fimbriae and flagellum, impacting the bacterium's ability to aggregate in bladder epithelial cells. Deletion of tusDCB resulted in decreased virulence against urinary tract infection mice. Moreover, mutant TusDCB lacking sulfur transfer activity and tusE- and mnmA mutants revealed the indispensability of TusDCB's sulfur transfer activity for UPEC pathogenicity. The study extends its relevance to highly pathogenic, multidrug-resistant strains, where tusDCB deletion reduced virulence-associated bacterial aggregation. These insights not only deepen our understanding of the interplay between tRNA sulfur modification and bacterial pathogenesis but also highlight TusDCB as a potential therapeutic target against UPEC strains resistant to conventional antimicrobial agents.
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Affiliation(s)
- Yumika Sato
- Department of Bacteriology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Ayako Takita
- Department of Bacteriology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Kazutomo Suzue
- Department of Infectious Diseases and Host Defense, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Yusuke Hashimoto
- Department of Bacteriology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Suguru Hiramoto
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Masami Murakami
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Haruyoshi Tomita
- Department of Bacteriology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
- Laboratory of Bacterial Drug Resistance, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi Maebashi, Gunma, 371-8511, Japan
| | - Hidetada Hirakawa
- Department of Bacteriology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan.
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2
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Mocăniță M, Martz K, D’Costa VM. Bacterial Pathogen-Mediated Suppression of Host Trafficking to Lysosomes: Fluorescence Microscopy-Based DQ-Red BSA Analysis. Bio Protoc 2024; 14:e4951. [PMID: 38464940 PMCID: PMC10917698 DOI: 10.21769/bioprotoc.4951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/04/2023] [Accepted: 02/05/2024] [Indexed: 03/12/2024] Open
Abstract
Intracellular bacterial pathogens have evolved to be adept at manipulating host cellular function for the benefit of the pathogen, often by means of secreted virulence factors that target host pathways for modulation. The lysosomal pathway is an essential cellular response pathway to intracellular pathogens and, as such, represents a common target for bacterial-mediated evasion. Here, we describe a method to quantitatively assess bacterial pathogen-mediated suppression of host cell trafficking to lysosomes, using Salmonella enterica serovar Typhimurium infection of epithelial cells as a model. This live-cell imaging assay involves the use of a BODIPY TR-X conjugate of BSA (DQ-Red BSA) that traffics to and fluoresces in functional lysosomes. This method can be adapted to study infection with a broad array of pathogens in diverse host cell types. It is capable of being applied to identify secreted virulence factors responsible for a phenotype of interest as well as domains within the bacterial protein that are important for mediating the phenotype. Collectively, these tools can provide invaluable insight into the mechanisms of pathogenesis of a diverse array of pathogenic bacteria, with the potential to uncover virulence factors that may be suitable targets for therapeutic intervention. Key features • Infection-based analysis of bacterial-mediated suppression of host trafficking to lysosomes, using Salmonella enterica serovar Typhimurium infection of human epithelial cells as a model. • Live microscopy-based analysis allows for the visualization of individually infected host cells and is amenable to phenotype quantification. • Assay can be adapted to a broad array of pathogens and diverse host cell types. • Assay can identify virulence factors mediating a phenotype and protein domains that mediate a phenotype.
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Affiliation(s)
- Mădălina Mocăniță
- Department of Biochemistry, Microbiology and
Immunology, University of Ottawa, Ottawa, ON, Canada
- Centre for Infection, Immunity and Inflammation,
University of Ottawa, Ottawa, ON, Canada
| | - Kailey Martz
- Department of Biochemistry, Microbiology and
Immunology, University of Ottawa, Ottawa, ON, Canada
- Centre for Infection, Immunity and Inflammation,
University of Ottawa, Ottawa, ON, Canada
| | - Vanessa M. D’Costa
- Department of Biochemistry, Microbiology and
Immunology, University of Ottawa, Ottawa, ON, Canada
- Centre for Infection, Immunity and Inflammation,
University of Ottawa, Ottawa, ON, Canada
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3
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Terlouw D, Boot A, Ducarmon QR, Nooij S, Suerink M, van Leerdam ME, van Egmond D, Tops CM, Zwittink RD, Ruano D, Langers AMJ, Nielsen M, van Wezel T, Morreau H. Enrichment of colibactin-associated mutational signatures in unexplained colorectal polyposis patients. BMC Cancer 2024; 24:104. [PMID: 38238650 PMCID: PMC10797792 DOI: 10.1186/s12885-024-11849-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 01/05/2024] [Indexed: 01/22/2024] Open
Abstract
BACKGROUND Colibactin, a genotoxin produced by polyketide synthase harboring (pks+) bacteria, induces double-strand breaks and chromosome aberrations. Consequently, enrichment of pks+Escherichia coli in colorectal cancer and polyposis suggests a possible carcinogenic effect in the large intestine. Additionally, specific colibactin-associated mutational signatures; SBS88 and ID18 in the Catalogue of Somatic Mutations in Cancer database, are detected in colorectal carcinomas. Previous research showed that a recurrent APC splice variant perfectly fits SBS88. METHODS In this study, we explore the presence of colibactin-associated signatures and fecal pks in an unexplained polyposis cohort. Somatic targeted Next-Generation Sequencing (NGS) was performed for 379 patients. Additionally, for a subset of 29 patients, metagenomics was performed on feces and mutational signature analyses using Whole-Genome Sequencing (WGS) on Formalin-Fixed Paraffin Embedded (FFPE) colorectal tissue blocks. RESULTS NGS showed somatic APC variants fitting SBS88 or ID18 in at least one colorectal adenoma or carcinoma in 29% of patients. Fecal metagenomic analyses revealed enriched presence of pks genes in patients with somatic variants fitting colibactin-associated signatures compared to patients without variants fitting colibactin-associated signatures. Also, mutational signature analyses showed enrichment of SBS88 and ID18 in patients with variants fitting these signatures in NGS compared to patients without. CONCLUSIONS These findings further support colibactins ability to mutagenize colorectal mucosa and contribute to the development of colorectal adenomas and carcinomas explaining a relevant part of patients with unexplained polyposis.
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Affiliation(s)
- Diantha Terlouw
- Department of Pathology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Arnoud Boot
- Department of Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | - Quinten R Ducarmon
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sam Nooij
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Manon Suerink
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Monique E van Leerdam
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Demi van Egmond
- Department of Pathology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands
| | - Carli M Tops
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Romy D Zwittink
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Dina Ruano
- Department of Pathology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands
| | - Alexandra M J Langers
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Maartje Nielsen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Tom van Wezel
- Department of Pathology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands
| | - Hans Morreau
- Department of Pathology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands.
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4
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Nomura K, Imboden LA, Tanaka H, He SY. Multiple host targets of Pseudomonas effector protein HopM1 form a protein complex regulating apoplastic immunity and water homeostasis. bioRxiv 2023:2023.07.31.551310. [PMID: 37577537 PMCID: PMC10418078 DOI: 10.1101/2023.07.31.551310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Bacterial type III effector proteins injected into the host cell play a critical role in mediating bacterial interactions with plant and animal hosts. Notably, some bacterial effectors are reported to target sequence-unrelated host proteins with unknown functional relationships. The Pseudomonas syringae effector HopM1 is such an example; it interacts with and/or degrades several HopM1-interacting (MIN) Arabidopsis proteins, including HopM1-interacting protein 2 (MIN2/RAD23), HopM1-interacting protein 7 (MIN7/BIG5), HopM1-interacting protein 10 (MIN10/14-3-3ĸ), and HopM1-interacting protein 13 (MIN13/BIG2). In this study, we purified the MIN7 complex formed in planta and found that it contains MIN7, MIN10, MIN13, as well as a tetratricopeptide repeat protein named HLB1. Mutational analysis showed that, like MIN7, HLB1 is required for pathogen-associated molecular pattern (PAMP)-, effector-, and benzothiadiazole (BTH)-triggered immunity. HLB1 is recruited to the trans-Golgi network (TGN)/early endosome (EE) in a MIN7-dependent manner. Both min7 and hlb1 mutant leaves contained elevated water content in the leaf apoplast and artificial water infiltration into the leaf apoplast was sufficient to phenocopy immune-suppressing phenotype of HopM1. These results suggest that multiple HopM1-targeted MIN proteins form a protein complex with a dual role in modulating water level and immunity in the apoplast, which provides an explanation for the dual phenotypes of HopM1 during bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
| | - Lori Alice Imboden
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
| | - Hirokazu Tanaka
- Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa 214-0033, Japan
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
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5
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Hisyam Bin Ismail CMK, Raihan Mohammad Shabani N, Chuah C, Hassan Z, Bakar Abdul Majeed A, Herng Leow C, Kaur Banga Singh K, Yee Leow C. Shigella iron-binding proteins: An insight into molecular physiology, pathogenesis, and potential target vaccine development. Vaccine 2022; 40:3991-3998. [PMID: 35660036 DOI: 10.1016/j.vaccine.2022.05.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 11/21/2021] [Accepted: 05/19/2022] [Indexed: 12/01/2022]
Abstract
Shigella is a well-known etiological agent responsible for intestinal infection among children, the elderly, and immunocompromised people ranging from mild to severe cases. Shigellosis remains endemic in Malaysia and yet there is no commercial vaccine available to eradicate the disease. Iron is an essential element for the survival of Shigella within the host. Hence, it is required for regulating metabolic mechanisms and virulence determinants. Alteration of iron status in the extracellular environment directly triggers the signal in enteropathogenic bacterial, providing information that they are in a hostile environment. To survive in an iron-limited environment, molecular regulation of iron-binding proteins plays a vital role in facilitating the transportation and utilization of sufficient iron sources. Given the importance of iron molecules for bacterial survival and pathogenicity, this review summarizes the physiological role of iron-binding proteins in bacterial survival and their potential use in vaccine and therapeutic developments.
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Affiliation(s)
| | - Nor Raihan Mohammad Shabani
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia; Faculty of Health Sciences, Universiti Teknologi MARA, Kampus Bertam, 13200 Kepala Batas, Penang, Malaysia
| | - Candy Chuah
- Department of Medical and Parasitology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia; Faculty of Health Sciences, Universiti Teknologi MARA, Kampus Bertam, 13200 Kepala Batas, Penang, Malaysia
| | - Zurina Hassan
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
| | - Abu Bakar Abdul Majeed
- Faculty of Pharmacy, Universiti Teknologi MARA, Kampus Puncak Alam, 42300 Kuala Selangor, Selangor, Malaysia
| | - Chiuan Herng Leow
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
| | - Kirnpal Kaur Banga Singh
- Department of Medical and Parasitology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - Chiuan Yee Leow
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.
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6
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Yi B, Dalpke AH. Revisiting the intrageneric structure of the genus Pseudomonas with complete whole genome sequence information: Insights into diversity and pathogen-related genetic determinants. Infect Genet Evol 2022; 97:105183. [PMID: 34920102 DOI: 10.1016/j.meegid.2021.105183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 08/09/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
Pseudomonas spp. exhibit considerable differences in host specificity and virulence. Most Pseudomonas species were isolated exclusively from environmental sources, ranging from soil to plants, but some Pseudomonas species have been detected from versatile sources, including both human host and environmental sources. Understanding genome variations that generate the tremendous diversity in Pseudomonas biology is important in controlling the incidence of infections. With a data set of 704 Pseudomonas complete whole genome sequences representing 186 species, Pseudomonas intrageneric structure was investigated by hierarchical clustering based on average nucleotide identity, and by phylogeny analysis based on concatenated core-gene alignment. Further comparative functional analyses indicated that Pseudomonas species only living in natural habitats lack multiple functions that are important in the regulation of bacterial pathogenesis, indicating the possession of these functions might be characteristic of Pseudomonas human pathogens. Moreover, we have performed pan-genome based homogeneity analyses, and detected genes with conserved structures but diversified functions across the Pseudomonas genomes, suggesting these genes play a role in driving diversity. In summary, this study provided insights into the dynamics of genome diversity and pathogen-related genetic determinants in Pseudomonas, which might help the development of more targeted antibiotics for the treatment of Pseudomonas infections.
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Affiliation(s)
- Buqing Yi
- Institute of Medical Microbiology and Virology, Medical Faculty, Technische Universität Dresden, Dresden, Germany.
| | - Alexander H Dalpke
- Institute of Medical Microbiology and Virology, Medical Faculty, Technische Universität Dresden, Dresden, Germany.
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7
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Mouriño S, Wilks A. Extracellular haem utilization by the opportunistic pathogen Pseudomonas aeruginosa and its role in virulence and pathogenesis. Adv Microb Physiol 2021; 79:89-132. [PMID: 34836613 DOI: 10.1016/bs.ampbs.2021.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Iron is an essential micronutrient for all bacteria but presents a significant challenge given its limited bioavailability. Furthermore, iron's toxicity combined with the need to maintain iron levels within a narrow physiological range requires integrated systems to sense, regulate and transport a variety of iron complexes. Most bacteria encode systems to chelate and transport ferric iron (Fe3+) via siderophore receptor mediated uptake or via cytoplasmic energy dependent transport systems. Pathogenic bacteria have further lowered the barrier to iron acquisition by employing systems to utilize haem as a source of iron. Haem, a lipophilic and toxic molecule, presents a significant challenge for transport into the cell. As such pathogenic bacteria have evolved sophisticated cell surface signaling (CSS) and transport systems to sense and obtain haem from the host. Once internalized haem is cleaved by both oxidative and non-oxidative mechanisms to release iron. Herein we summarize our current understanding of the mechanism of haem sensing, uptake and utilization in Pseudomonas aeruginosa, its role in pathogenesis and virulence, and the potential of these systems as antimicrobial targets.
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8
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Barzelighi HM, Esfahani BN, Bakhshi B, Daraei B, Moghim S, Fazeli H. Influence of Heterologously Expressed azurin from Pseudomonas aeruginosa on the Adhesion and Invasion of Pathogenic Bacteria to the Caco-2 Cell Line. Probiotics Antimicrob Proteins 2020; 12:697-704. [PMID: 31364004 DOI: 10.1007/s12602-019-09573-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
This study proposed to investigate the effect of azurin on the major stages of pathogenesis (adhesion and invasion) of intestinal bacterial pathogens (Salmonella spp. and Escherichia coli) and epithelial pathogens (Staphylococcus aureus and Pseudomonas aeruginosa) on the human colorectal adenocarcinoma (Caco-2) cell line. Azurin protein was produced by cloning the azurin gene into pET21a and heterologous expression in E. coli BL21. The protein was purified using affinity chromatography and confirmed by Western blotting. The purified protein was evaluated by three experiments of adhesion and invasion assays, including exclusion, competition, and replacement. Azurin was observed to significantly inhibit the attachment and invasion of S. aureus, Salmonella spp., and E. coli, while no such inhibitory effects were observed on P. aeruginosa. In fact, the protein increased the adhesion of P. aeruginosa to the cell. In conclusion, our study proposes that azurin is a potential prophylactic or preventive helper candidate to inhibit the attachment and invasion of pathogenic bacteria to host cells and reduce the progression of the infection process. Our study also reveals the involvement of azurin in bacteria-host cell interactions, providing novel and important insights toward the elucidation of its biological function in this field. Thus, this study provides new opportunities to use azurin as an adjunct therapy against critical stages of infection by a wide range of pathogenic bacteria.
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9
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Abstract
The role of guanine quadruplexes (G4) in fundamental biological processes like DNA replication, transcription, translation and telomere maintenance is recognized. G4 structure dynamics is regulated by G4 structure binding proteins and is thought to be crucial for the maintenance of genome integrity in both prokaryotic and eukaryotic cells. Growing research over the last decade has expanded the existing knowledge of the functional diversity of G4 (DNA and RNA) structures across the working models. The control of G4 structure dynamics using G4 binding drugs has been suggested as the putative targets in the control of cancer and bacterial pathogenesis. This review has brought forth the collections of recent information that indicate G4 (mostly G4 DNA) roles in microbial pathogenesis, DNA damaging stress response in bacteria and mammalian cells. Studies in mitochondrial gene function regulation by G4s have also been underscored. Finally, the interdependence of G4s and epigenetic modifications and their speculated medical implications through G4 interacting proteins has been discussed.
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Affiliation(s)
- Shruti Mishra
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India.,Life Sciences, Homi Bhabha National Institute (DAE Deemed to be University), Mumbai, India
| | - Swathi Kota
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India.,Life Sciences, Homi Bhabha National Institute (DAE Deemed to be University), Mumbai, India
| | - Reema Chaudhary
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India.,Life Sciences, Homi Bhabha National Institute (DAE Deemed to be University), Mumbai, India
| | - H S Misra
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India.,Life Sciences, Homi Bhabha National Institute (DAE Deemed to be University), Mumbai, India
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10
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Mea HJ, Yong PVC, Wong EH. An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation. Microbiol Res 2021; 247:126722. [PMID: 33618061 DOI: 10.1016/j.micres.2021.126722] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/13/2022]
Abstract
The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.
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Affiliation(s)
- Hing Jian Mea
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Phelim Voon Chen Yong
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Eng Hwa Wong
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia.
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11
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Abstract
The release of extracellular vesicles (EVs) is a process conserved across the three domains of life. Amongst prokaryotes, EVs produced by Gram-negative bacteria, termed outer membrane vesicles (OMVs), were identified more than 50 years ago and a wealth of literature exists regarding their biogenesis, composition and functions. OMVs have been implicated in benefiting numerous metabolic functions of their parent bacterium. Additionally, OMVs produced by pathogenic bacteria have been reported to contribute to pathology within the disease setting. By contrast, the release of EVs from Gram-positive bacteria, known as membrane vesicles (MVs), has only been widely accepted within the last decade. As such, there is a significant disproportion in knowledge regarding MVs compared to OMVs. Here we provide an overview of the literature regarding bacterial membrane vesicles (BMVs) produced by pathogenic and commensal bacteria. We highlight the mechanisms of BMV biogenesis and their roles in assisting bacterial survival, in addition to discussing their functions in promoting disease pathologies and their potential use as novel therapeutic strategies.
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Affiliation(s)
- William J Gilmore
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC, Australia
- Research Centre for Extracellular Vesicles, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Natalie J Bitto
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC, Australia
- Research Centre for Extracellular Vesicles, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Maria Kaparakis-Liaskos
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC, Australia.
- Research Centre for Extracellular Vesicles, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia.
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12
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Rosales-Reyes R, Vargas-Roldán SY, Lezana-Fernández JL, Santos-Preciado JI. Pseudomonas Aeruginosa: Genetic Adaptation, A Strategy for its Persistence in Cystic Fibrosis. Arch Med Res 2020; 52:357-361. [PMID: 33309309 DOI: 10.1016/j.arcmed.2020.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/25/2020] [Accepted: 12/03/2020] [Indexed: 10/22/2022]
Abstract
Cystic fibrosis (CF) is a progressive autosomal recessive genetic disease that principally affects the respiratory and digestive systems. It is a chronic disease that has no cure. Symptoms often include chronic cough, lung infections, and shortness of breath. Children with cystic fibrosis present failure to thrive as manifested by low weight and height for age. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (cftr) gene that codes for a cell membrane protein of epithelial tissues and affects multiple organ systems in the human body. Mutations on the CFTR causes dysfunctional electrolyte regulation affecting intracellular water content. Defective CFTR function in airways produce a dehydrated and sticky mucus that leads the establishment of bacterial chronic infection that ultimate decrease the lung function. During the first decade of life, affected individuals are colonized principally by non typable Haemophilus influenzae and Staphylococcus aureus. During the second decade, Pseudomonas aeruginosa becomes the most dominant pathogen and persists throughout the remainder of their lives. In this work, we describe the mechanisms used by P. aeruginosa to adapt and persist in lungs of individuals with cystic fibrosis.
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Affiliation(s)
- Roberto Rosales-Reyes
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, México.
| | - Silvia Yalid Vargas-Roldán
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - José Luis Lezana-Fernández
- Laboratorio de Fisiología Respiratoria y Clínica de Fibrosis Quística, Hospital Infantil de México Federico Gómez, Ciudad de México, México; Dirección Médica, Asociación Mexicana de Fibrosis Quística, Ciudad de México, México
| | - José Ignacio Santos-Preciado
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, México
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13
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Danilo de Oliveira W, Lopes Barboza MG, Faustino G, Yamanaka Inagaki WT, Sanches MS, Takayama Kobayashi RK, Vespero EC, Dejato Rocha SP. Virulence, resistance and clonality of Proteus mirabilis isolated from patients with community-acquired urinary tract infection (CA-UTI) in Brazil. Microb Pathog 2021; 152:104642. [PMID: 33246088 DOI: 10.1016/j.micpath.2020.104642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022]
Abstract
Urinary tract infections (UTIs) are among the most common human infections, both in hospitals and in communities. Proteus mirabilis is known to cause community-acquired urinary tract infection (CA-UTI) and is an important causative agent of nosocomial UTIs. The pathogenesis of this species is related to its ability to manifest virulence factors, such as biofilms, adhesion molecules, urease, proteases, siderophores, and toxins. In this study, we investigated the virulence, sensitivity to antimicrobials, and clonal relationship of 183 strains isolated from the urine of CA-UTI patients in Londrina, Paraná State, Brazil. A total of 100% of the strains were positive for hpmA, ptA, zapA, mrpA, pmfA, ireA, and atfA virulence genes. The ucaA gene was positive in 81.4% of the cases. The strains showed high rates of sensitivity to the evaluated antimicrobials, and only one was ESBL-positive. All the tested bacteria showed the capacity to form biofilms: 73.2% had a very strong intensity, while 25.7% had a strong intensity, and 1.1% had a moderate intensity. Regarding clonality, 40 clonal clusters were found among the microorganisms tested. Our results showed that strains of P. mirabilis isolated from CA-UTI patients have several virulence factors. Although the urinary clinical isolates studied showed high sensitivity to antimicrobials, the strains showed a strong capacity to form biofilms, making antibiotic therapy difficult. In addition, it was observed that there were clones of P. mirabilis circulating in the city of Londrina. All strains presented a variety of virulence genes. It was observed that there were clones of P. mirabilis circulating. 98.1% of strains produced strong or very strong biofilm.
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Man L, Dale AL, Klare WP, Cain JA, Sumer-Bayraktar Z, Niewold P, Solis N, Cordwell SJ. Proteomics of Campylobacter jejuni Growth in Deoxycholate Reveals Cj0025c as a Cystine Transport Protein Required for Wild-type Human Infection Phenotypes. Mol Cell Proteomics 2020; 19:1263-1280. [PMID: 32376616 PMCID: PMC8015009 DOI: 10.1074/mcp.ra120.002029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/01/2020] [Indexed: 12/12/2022] Open
Abstract
Campylobacter jejuni is a major cause of food-borne gastroenteritis. Proteomics by label-based two-dimensional liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) identified proteins associated with growth in 0.1% sodium deoxycholate (DOC, a component of gut bile salts), and system-wide validation was performed by data-independent acquisition (DIA-SWATH-MS). LC-MS/MS quantified 1326 proteins (∼82% of the predicted C. jejuni proteome), of which 1104 were validated in additional biological replicates by DIA-SWATH-MS. DOC resulted in a profound proteome shift with 512 proteins showing significantly altered abundance. Induced proteins were associated with flagellar motility and antibiotic resistance; and these correlated with increased DOC motility and resistance to polymyxin B and ciprofloxacin. DOC also increased human Caco-2 cell adherence and invasion. Abundances of proteins involved in nutrient transport were altered by DOC and aligned with intracellular changes to their respective carbon sources. DOC increased intracellular levels of sulfur-containing amino acids (cysteine and methionine) and the dipeptide cystine (Cys-Cys), which also correlated with reduced resistance to oxidative stress. A DOC induced transport protein was Cj0025c, which has sequence similarity to bacterial Cys-Cys transporters. Deletion of cj0025c (Δcj0025c) resulted in proteome changes consistent with sulfur starvation, as well as attenuated invasion, reduced motility, atypical morphology, increased antimicrobial susceptibility and poor biofilm formation. Targeted metabolomics showed Δcj0025c could use known C. jejuni amino and organic acid substrates commensurate with wild-type. Medium Cys-Cys levels however, were maintained in Δcj0025c relative to wild-type. A toxic Cys-Cys mimic (selenocystine) inhibited wild-type growth, but not Δcj0025c Provision of an alternate sulfur source (2 mm thiosulfate) restored Δcj0025c motility. Our data confirm that Cj0025c is a Cys-Cys transporter that we have named TcyP consistent with the nomenclature of homologous proteins in other species.
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Affiliation(s)
- Lok Man
- School of Life and Environmental Sciences, The University of Sydney, Australia; Charles Perkins Centre, The University of Sydney, Australia
| | - Ashleigh L Dale
- School of Life and Environmental Sciences, The University of Sydney, Australia; Charles Perkins Centre, The University of Sydney, Australia
| | - William P Klare
- School of Life and Environmental Sciences, The University of Sydney, Australia; Charles Perkins Centre, The University of Sydney, Australia
| | - Joel A Cain
- School of Life and Environmental Sciences, The University of Sydney, Australia; Charles Perkins Centre, The University of Sydney, Australia
| | - Zeynep Sumer-Bayraktar
- School of Life and Environmental Sciences, The University of Sydney, Australia; Charles Perkins Centre, The University of Sydney, Australia
| | - Paula Niewold
- Charles Perkins Centre, The University of Sydney, Australia; Discipline of Pathology, School of Medical Sciences, The University of Sydney, Australia
| | - Nestor Solis
- School of Life and Environmental Sciences, The University of Sydney, Australia
| | - Stuart J Cordwell
- School of Life and Environmental Sciences, The University of Sydney, Australia; Charles Perkins Centre, The University of Sydney, Australia; Discipline of Pathology, School of Medical Sciences, The University of Sydney, Australia; Sydney Mass Spectrometry, The University of Sydney, Australia.
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15
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Novotny LA, Goodman SD, Bakaletz LO. Redirecting the immune response towards immunoprotective domains of a DNABII protein resolves experimental otitis media. NPJ Vaccines 2019; 4:43. [PMID: 31632744 PMCID: PMC6791836 DOI: 10.1038/s41541-019-0137-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/13/2019] [Indexed: 12/18/2022] Open
Abstract
The chronicity and recurrence of many bacterial diseases is largely attributable to the presence of a biofilm, and eradication of these structures is confounded by an extracellular DNA-rich matrix. DNABII proteins, including integration host factor (IHF), are critical components of the matrix formed by all human pathogens tested to date. Whereas the natural adaptive immune response to IHF is against non-protective epitopes within the carboxyl-terminal region, antibodies against the DNA-binding “tips” induce biofilm collapse. We designed a “tip-chimer” immunogen to mimic the DNA-binding regions within the α-subunit and β-subunit of IHF from nontypeable Haemophilus influenzae (IHFNTHi). Re-direction of the natural adaptive immune response toward immunoprotective domains disrupted NTHi biofilms in vitro and in an experimental model of otitis media. Our data support the rational design of a powerful therapeutic approach, and also that of a DNABII-directed vaccine antigen that would avoid augmentation of any pre-existing natural, but nonprotective, immune response. Bacterial biofilms are characterized by the presence of a protective extracellular polymeric substance (EPS) that incorporates both eDNA and members of the DNABII family of bacterial DNA-binding proteins. Antibodies against the “tips” of these DNA binding-domains can cause biofilm collapse, but these epitopes are masked from the host adaptive immune system when bound to eDNA, making biofilm eradication difficult. Here, the team led by Lauren Bakaletz used a chimeric peptide to generate tip-specific antibodies against nontypeable Haemophilus influenzae to treat biofilms in vitro and in vivo. The “tip-chimer” contained the immunoprotective domains from the DNA-binding tips of a DNABII protein, integration host factor (IHF), expressed by nontypeable Haemophilus influenzae. The consequent antibodies disrupted H. influenzae biofilms in vitro and were used to treat a chinchilla model of experimental otitis media when inoculated directly into the middle ear, resulting in reduced bacterial load and clearance of already established mucosal biofilms. These findings suggest that redirecting the host adaptive immune response towards the immunoprotective tips of DNABII proteins could provide a strategy to eradicate biofilms caused by various pathogens that produce these proteins.
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Affiliation(s)
- L A Novotny
- 1Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205 USA
| | - S D Goodman
- 1Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205 USA.,2The Ohio State University College of Medicine, Columbus, OH 43210 USA
| | - L O Bakaletz
- 1Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205 USA.,2The Ohio State University College of Medicine, Columbus, OH 43210 USA
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16
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Cain JA, Dale AL, Niewold P, Klare WP, Man L, White MY, Scott NE, Cordwell SJ. Proteomics Reveals Multiple Phenotypes Associated with N-linked Glycosylation in Campylobacter jejuni. Mol Cell Proteomics 2019; 18:715-734. [PMID: 30617158 PMCID: PMC6442361 DOI: 10.1074/mcp.ra118.001199] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 12/31/2018] [Indexed: 12/11/2022] Open
Abstract
Campylobacter jejuni is a major gastrointestinal pathogen generally acquired via consumption of poorly prepared poultry. N-linked protein glycosylation encoded by the pgl gene cluster targets >80 membrane proteins and is required for both nonsymptomatic chicken colonization and full human virulence. Despite this, the biological functions of N-glycosylation remain unknown. We examined the effects of pgl gene deletion on the C. jejuni proteome using label-based liquid chromatography/tandem mass spectrometry (LC-MS/MS) and validation using data independent acquisition (DIA-SWATH-MS). We quantified 1359 proteins corresponding to ∼84% of the C. jejuni NCTC 11168 genome, and 1080 of these were validated by DIA-SWATH-MS. Deletion of the pglB oligosaccharyltransferase (ΔpglB) resulted in a significant change in abundance of 185 proteins, 137 of which were restored to their wild-type levels by reintroduction of pglB (Δaaz.batpglB::ΔpglB). Deletion of pglB was associated with significantly reduced abundances of pgl targets and increased stress-related proteins, including ClpB, GroEL, GroES, GrpE and DnaK. pglB mutants demonstrated reduced survival following temperature (4 °C and 46 °C) and osmotic (150 mm NaCl) shock and altered biofilm phenotypes compared with wild-type C. jejuni Targeted metabolomics established that pgl negative C. jejuni switched from aspartate (Asp) to proline (Pro) uptake and accumulated intracellular succinate related to proteome changes including elevated PutP/PutA (proline transport and utilization), and reduced DctA/DcuB (aspartate import and succinate export, respectively). ΔpglB chemotaxis to some substrates (Asp, glutamate, succinate and α-ketoglutarate) was reduced and associated with altered abundance of transducer-like (Tlp) proteins. Glycosylation negative C. jejuni were depleted of all respiration-associated proteins that allow the use of alternative electron acceptors under low oxygen. We demonstrate for the first time that N-glycosylation is required for a specific enzyme activity (Nap nitrate reductase) that is associated with reduced abundance of the NapAB glycoproteins. These data indicate a multifactorial role for N-glycosylation in C. jejuni physiology.
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Affiliation(s)
- Joel A Cain
- From the ‡School of Life and Environmental Sciences,; §Charles Perkins Centre
| | - Ashleigh L Dale
- From the ‡School of Life and Environmental Sciences,; §Charles Perkins Centre
| | - Paula Niewold
- §Charles Perkins Centre,; ¶Discipline of Pathology, School of Medical Sciences, The University of Sydney, Australia 2006
| | - William P Klare
- From the ‡School of Life and Environmental Sciences,; §Charles Perkins Centre
| | - Lok Man
- From the ‡School of Life and Environmental Sciences,; §Charles Perkins Centre
| | - Melanie Y White
- §Charles Perkins Centre,; ¶Discipline of Pathology, School of Medical Sciences, The University of Sydney, Australia 2006
| | | | - Stuart J Cordwell
- From the ‡School of Life and Environmental Sciences,; §Charles Perkins Centre,; ¶Discipline of Pathology, School of Medical Sciences, The University of Sydney, Australia 2006;; ‖Sydney Mass Spectrometry, The University of Sydney, Australia 2006.
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17
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Masukagami Y, Nijagal B, Tseng CW, Dayalan S, Tivendale KA, Markham PF, Browning GF, Sansom FM. Metabolite profiling of Mycoplasma gallisepticum mutants, combined with bioinformatic analysis, can reveal the likely functions of virulence-associated genes. Vet Microbiol 2018; 223:160-167. [PMID: 30173742 DOI: 10.1016/j.vetmic.2018.08.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/01/2018] [Accepted: 08/01/2018] [Indexed: 11/18/2022]
Abstract
Mycoplasma gallisepticum is an economically important pathogen of commercial poultry. An improved understanding of M. gallisepticum pathogenesis is required to develop better control methods. We recently identified a number of M. gallisepticum mutants with defects in colonization and persistence in chickens using signature-tagged transposon mutagenesis. Loss of virulence was associated with mutations in a putative oligopeptide/dipeptide (opp/dpp) ATP-binding cassette (ABC) transporter (where the transposon was inserted into the MGA_0220 (oppD1) gene and two hypothetical proteins (encoded by MGA_1102 and MGA_0588), one of which (MGA_1102) contains a putative peptidase motif. To further characterise the function of these proteins, we compared the metabolome of each transposon mutant with that of wild type bacteria. Two independent LC/MS analyses revealed consistent significant decreases in the abundances of several amino acids and the dipeptide alanyl-glycine (Ala-Gly) in the MGA_0220 mutant, consistent with this protein being a peptide transporter. Similarly, lysine and Ala-Gly were significantly decreased in the MGA_1102 mutant, consistent with our bioinformatic analysis suggesting that MGA_1102 encodes a membrane-located peptidase. Few differences were observed in metabolite levels in the MGA_0588 mutant, suggesting that the disrupted protein has a non-metabolic role. Overall, this study indicates that metabolomics is a useful tool in the functional analysis of mutants.
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Affiliation(s)
- Yumiko Masukagami
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Brunda Nijagal
- Metabolomics Australia, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Victoria, Australia
| | - Chi-Wen Tseng
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Saravanan Dayalan
- Metabolomics Australia, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Victoria, Australia
| | - Kelly A Tivendale
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Philip F Markham
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Glenn F Browning
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Fiona M Sansom
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia.
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18
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Kobayashi SD, Malachowa N, DeLeo FR. Neutrophils and Bacterial Immune Evasion. J Innate Immun 2018; 10:432-441. [PMID: 29642066 DOI: 10.1159/000487756] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 02/14/2018] [Indexed: 12/31/2022] Open
Abstract
Neutrophils are an important component of the innate immune system and provide a front line of defense against bacterial infection. Although most bacteria are killed readily by neutrophils, some bacterial pathogens have the capacity to circumvent destruction by these host leukocytes. The ability of bacterial pathogens to avoid killing by neutrophils often involves multiple attributes or characteristics, including the production of virulence molecules. These molecules are diverse in composition and function, and collectively have the potential to alter or inhibit neutrophil recruitment, phagocytosis, bactericidal activity, and/or apoptosis. Here, we review the ability of bacteria to target these processes.
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19
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Chamoun MN, Blumenthal A, Sullivan MJ, Schembri MA, Ulett GC. Bacterial pathogenesis and interleukin-17: interconnecting mechanisms of immune regulation, host genetics, and microbial virulence that influence severity of infection. Crit Rev Microbiol 2018; 44:465-486. [PMID: 29345518 DOI: 10.1080/1040841x.2018.1426556] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Interleukin-17 (IL-17) is a pro-inflammatory cytokine involved in the control of many different disorders, including autoimmune, oncogenic, and diverse infectious diseases. In the context of infectious diseases, IL-17 protects the host against various classes of microorganisms but, intriguingly, can also exacerbate the severity of some infections. The regulation of IL-17 expression stems, in part, from the activity of Interleukin-23 (IL-23), which drives the maturation of different classes of IL-17-producing cells that can alter the course of infection. In this review, we analyze IL-17/IL-23 signalling in bacterial infection, and examine the interconnecting mechanisms that link immune regulation, host genetics, and microbial virulence in the context of bacterial pathogenesis. We consider the roles of IL-17 in both acute and chronic bacterial infections, with a focus on mouse models of human bacterial disease that involve infection of mucosal surfaces in the lungs, urogenital, and gastrointestinal tracts. Polymorphisms in IL-17-encoding genes in humans, which have been associated with heightened host susceptibility to some bacterial pathogens, are discussed. Finally, we examine the implications of IL-17 biology in infectious diseases for the development of novel therapeutic strategies targeted at preventing bacterial infection.
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Affiliation(s)
- Michelle N Chamoun
- a School of Medical Science, and Menzies Health Institute Queensland , Griffith University , Southport , Australia
| | - Antje Blumenthal
- b The University of Queensland Diamantina Institute, Translational Research Institute , Brisbane , Australia
| | - Matthew J Sullivan
- a School of Medical Science, and Menzies Health Institute Queensland , Griffith University , Southport , Australia
| | - Mark A Schembri
- c School of Chemistry and Molecular Biosciences, and Australian Infectious Disease Research Centre , The University of Queensland , Brisbane , Australia
| | - Glen C Ulett
- a School of Medical Science, and Menzies Health Institute Queensland , Griffith University , Southport , Australia
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20
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El Qaidi S, Wu M, Zhu C, Hardwidge PR. Salmonella, E. coli, and Citrobacter Type III Secretion System Effector Proteins that Alter Host Innate Immunity. Adv Exp Med Biol 2018; 1111:205-218. [PMID: 30411307 DOI: 10.1007/5584_2018_289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bacteria deliver virulence proteins termed 'effectors' to counteract host innate immunity. Protein-protein interactions within the host cell ultimately subvert the generation of an inflammatory response to the infecting pathogen. Here we briefly describe a subset of T3SS effectors produced by enterohemorrhagic Escherichia coli (EHEC), enteropathogenic E. coli (EPEC), Citrobacter rodentium, and Salmonella enterica that inhibit innate immune pathways. These effectors are interesting for structural and mechanistic reasons, as well as for their potential utility in being engineered to treat human autoimmune disorders associated with perturbations in NF-κB signaling.
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Affiliation(s)
- Samir El Qaidi
- College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Miaomiao Wu
- College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Congrui Zhu
- College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Philip R Hardwidge
- College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
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21
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Abstract
Bacterial luminescence allows for noninvasive continuous monitoring of promoter activity in a wide range of model systems. This chapter details various examples of use of the lux reporter system to measure promoter activity in bacteria using the vector pUC18T-mini-Tn7T-lux-Tp. Here, we describe the construction of promoter fusions with bacterial luciferase, and how to quantify promoter activity in real time in vitro and in vivo in plant, insect, and murine infection models.
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22
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Garcia M, Morello E, Garnier J, Barrault C, Garnier M, Burucoa C, Lecron JC, Si-Tahar M, Bernard FX, Bodet C. Pseudomonas aeruginosa flagellum is critical for invasion, cutaneous persistence and induction of inflammatory response of skin epidermis. Virulence 2018; 9:1163-1175. [PMID: 30070169 PMCID: PMC6086312 DOI: 10.1080/21505594.2018.1480830] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 05/21/2018] [Indexed: 12/22/2022] Open
Abstract
Pseudomonas aeruginosa, an opportunistic pathogen involved in skin and lung diseases, possesses numerous virulence factors, including type 2 and 3 secretion systems (T2SS and T3SS) and its flagellum, whose functions remain poorly known during cutaneous infection. Using isogenic mutants deleted from genes encoding each or all of these three virulence factors, we investigated their role in induction of inflammatory response and in tissue invasiveness in human primary keratinocytes and reconstructed epidermis. Our results showed that flagellum, but not T2SS and T3SS, is involved in induction of a large panel of cytokine, chemokine, and antimicrobial peptide (AMP) mRNA in the infected keratinocytes. Chemokine secretion and AMP tissular production were also dependent on the presence of the bacterial flagellum. This pro-inflammatory effect was significantly reduced in keratinocytes infected in presence of anti-toll-like receptor 5 (TLR5) neutralizing antibody. Bacterial invasion of human epidermis and persistence in a mouse model of sub-cutaneous infection were dependent on the P. aeruginosa flagellum. We demonstrated that flagellum constitutes the main virulence factor of P. aeruginosa involved not only in early induction of the epidermis inflammatory response but also in bacterial invasion and cutaneous persistence. P. aeruginosa is mainly sensed by TLR5 during the early innate immune response of human primary keratinocytes.
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Affiliation(s)
- Magali Garcia
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Laboratoire Inflammation Tissus Epithéliaux et Cytokines EA 4331, Université de Poitiers
, Poitiers, France
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Laboratoire de Virologie et Mycobactériologie, CHU de Poitiers
, Poitiers, France
| | - Eric Morello
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Centre d'Etude des Pathologies Respiratoires, INSERM UMR 1100, Université de Tours
, Tours, France
| | | | | | - Martine Garnier
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Laboratoire Inflammation Tissus Epithéliaux et Cytokines EA 4331, Université de Poitiers
, Poitiers, France
| | - Christophe Burucoa
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Laboratoire Inflammation Tissus Epithéliaux et Cytokines EA 4331, Université de Poitiers
, Poitiers, France
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Laboratoire de Bactériologie et Hygiène, CHU de Poitiers
, Poitiers, France
| | - Jean-Claude Lecron
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Laboratoire Inflammation Tissus Epithéliaux et Cytokines EA 4331, Université de Poitiers
, Poitiers, France
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Laboratoire d’Immunologie et Inflammation, CHU de Poitiers
, Poitiers, France
| | - Mustapha Si-Tahar
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Centre d'Etude des Pathologies Respiratoires, INSERM UMR 1100, Université de Tours
, Tours, France
| | | | - Charles Bodet
-
Laboratoire Inflammation Tissus Epithéliaux et Cytokines EA 4331, Université de Poitiers
, Poitiers, France
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23
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Abstract
Animal and plant pathogenic bacteria use type III secretion systems to translocate proteinaceous effectors to subvert innate immunity of their host organisms. Type III secretion/effector systems are a crucial pathogenicity factor in many bacterial pathogens of plants and animals. Pseudomonas syringae pv. tomato (Pst) DC3000 injects a total of 36 protein effectors that target a variety of host proteins. Studies of a subset of Pst DC3000 effectors demonstrated that bacterial effectors, once inside the host cell, are localized to different subcellular compartments, including plasma membrane, cytoplasm, mitochondria, chloroplast, and Trans-Golgi network, to carry out their virulence functions. Identifying the subcellular localization of bacterial effector proteins in host cells could provide substantial clues to understanding the molecular and cellular basis of the virulence activities of effector proteins. In this chapter, we present methods for transient or stable expression of bacterial effector proteins in tobacco and/or Arabidopsis thaliana for live cell imaging as well as confirming the subcellular localization in plants using fluorescent organelle markers or chemical treatment.
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Affiliation(s)
- Kyaw Aung
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Xiufang Xin
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Christy Mecey
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Sheng Yang He
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48824, USA.
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24
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Abstract
Rhomboid proteins are considered to be the most widespread membrane proteins across all forms of life. This superfamily comprises both active intramembrane serine proteases that catalyze the release of factors from the membrane, and a eukaryotic subset of non-catalytic members in which rhomboid architecture supports deviating functions. Although rhomboid was discovered in genetic studies of insect development, rhomboid research has broadened dramatically over the past 15 years; rhomboid enzymes are now the best biophysically understood of all intramembrane proteases, and are considered promising therapeutic targets for diseases ranging from parasitic infections to Parkinsonian neurodegeneration. Perhaps the most rapid progress has come with the catalytically inert rhomboid proteins, some of which regulate protein trafficking and/or function, and their prominence is underscored by clinical mutations. Such a diverse collection of advances mark an excellent point to review the state of this vibrant area of research, not because central questions have been answered, but instead because a firm grip in key areas has been established, and the field is now poised for breakthroughs.
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Affiliation(s)
- Siniša Urban
- Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Room 507 PCTB, 725 North Wolfe Street, Baltimore, MD, 21205, USA.
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25
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Jaworski DC, Cheng C, Nair ADS, Ganta RR. Amblyomma americanum ticks infected with in vitro cultured wild-type and mutants of Ehrlichia chaffeensis are competent to produce infection in naïve deer and dogs. Ticks Tick Borne Dis 2016; 8:60-64. [PMID: 27729288 DOI: 10.1016/j.ttbdis.2016.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 09/25/2016] [Accepted: 09/25/2016] [Indexed: 11/30/2022]
Abstract
Monocytic ehrlichiosis in people caused by the intracellular bacterium, Ehrlichia chaffeensis, is an emerging infectious disease transmitted by the lone star tick, Amblyomma americanum. Tick transmission disease models for ehrlichiosis require at least two hosts and two tick blood feeding episodes to recapitulate the natural transmission cycle. One blood feeding is necessary for the tick to acquire the infection from an infected host and the next feeding is needed to transmit the bacterium to a naïve host. We have developed a model for E. chaffeensis transmission that eliminates the entire tick acquisition stage while still producing high numbers of infected ticks that are also able to transmit infections to naïve hosts. Fully engorged A. americanum nymphs were ventrally needle-infected, possibly into the midgut, and following molting, the unfed adult ticks were used to infect naive deer and dogs. We have also described using the ticks infected by this method the transmission of both wild-type and transposon mutants of E. chaffeensis to its primary reservoir host, white tailed deer and to another known host, dog. The infection progression and IgG antibody responses in deer were similar to those observed with transmission feeding of ticks acquiring infection by natural blood feeding. The pathogen infections acquired by natural tick transmission and by feeding needle-infected ticks on animals were also similar to intravenous infections in causing persistent infections. Needle-infected ticks having the ability to transmit pathogens will be a valuable resource to substantially simplify the process of generating infected ticks and to study infection systems in vertebrate hosts where interference of other pathogens could be avoided.
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Affiliation(s)
- Deborah C Jaworski
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, United States; Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States.
| | - Chuanmin Cheng
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, United States
| | - Arathy D S Nair
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, United States
| | - Roman R Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, United States
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Fozo EM, Rucks EA. The Making and Taking of Lipids: The Role of Bacterial Lipid Synthesis and the Harnessing of Host Lipids in Bacterial Pathogenesis. Adv Microb Physiol 2016; 69:51-155. [PMID: 27720012 DOI: 10.1016/bs.ampbs.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to many stressful stimuli. A resulting adaptation is for pathogens to scavenge the host environment for readily available lipid sources. The pathogen takes advantage of these host-derived lipids to increase or decrease the rigidity of their own membranes, to provide themselves with valuable precursors to feed central metabolic pathways, or to impact host signalling and processes. Within, we review the diverse mechanisms that both extracellular and intracellular pathogens employ to alter their own membranes as well as their use of host-derived lipids in membrane synthesis and modification, in order to increase survival and perpetuate disease within the human host. Furthermore, we discuss how pathogen employed mechanistic utilization of host-derived lipids allows for their persistence, survival and potentiation of disease. A more thorough understanding of all of these mechanisms will have direct consequences for the development of new therapeutics, and specifically, therapeutics that target pathogens, while preserving normal flora.
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Affiliation(s)
- E M Fozo
- University of Tennessee, Knoxville, TN, United States.
| | - E A Rucks
- Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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Ebeling J, Knispel H, Hertlein G, Fünfhaus A, Genersch E. Biology of Paenibacillus larvae, a deadly pathogen of honey bee larvae. Appl Microbiol Biotechnol 2016; 100:7387-95. [PMID: 27394713 DOI: 10.1007/s00253-016-7716-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/28/2016] [Accepted: 06/30/2016] [Indexed: 01/23/2023]
Abstract
The gram-positive bacterium Paenibacillus larvae is the etiological agent of American Foulbrood of honey bees, a notifiable disease in many countries. Hence, P. larvae can be considered as an entomopathogen of considerable relevance in veterinary medicine. P. larvae is a highly specialized pathogen with only one established host, the honey bee larva. No other natural environment supporting germination and proliferation of P. larvae is known. Over the last decade, tremendous progress in the understanding of P. larvae and its interactions with honey bee larvae at a molecular level has been made. In this review, we will present the recent highlights and developments in P. larvae research and discuss the impact of some of the findings in a broader context to demonstrate what we can learn from studying "exotic" pathogens.
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Cott C, Thuenauer R, Landi A, Kühn K, Juillot S, Imberty A, Madl J, Eierhoff T, Römer W. Pseudomonas aeruginosa lectin LecB inhibits tissue repair processes by triggering β-catenin degradation. Biochim Biophys Acta 2016; 1863:1106-18. [PMID: 26862060 PMCID: PMC4859328 DOI: 10.1016/j.bbamcr.2016.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 01/31/2016] [Accepted: 02/05/2016] [Indexed: 01/08/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that induces severe lung infections such as ventilator-associated pneumonia and acute lung injury. Under these conditions, the bacterium diminishes epithelial integrity and inhibits tissue repair mechanisms, leading to persistent infections. Understanding the involved bacterial virulence factors and their mode of action is essential for the development of new therapeutic approaches. In our study we discovered a so far unknown effect of the P. aeruginosa lectin LecB on host cell physiology. LecB alone was sufficient to attenuate migration and proliferation of human lung epithelial cells and to induce transcriptional activity of NF-κB. These effects are characteristic of impaired tissue repair. Moreover, we found a strong degradation of β-catenin, which was partially recovered by the proteasome inhibitor lactacystin. In addition, LecB induced loss of cell-cell contacts and reduced expression of the β-catenin targets c-myc and cyclin D1. Blocking of LecB binding to host cell plasma membrane receptors by soluble l-fucose prevented these changes in host cell behavior and signaling, and thereby provides a powerful strategy to suppress LecB function. Our findings suggest that P. aeruginosa employs LecB as a virulence factor to induce β-catenin degradation, which then represses processes that are directly linked to tissue recovery.
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Affiliation(s)
- Catherine Cott
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Roland Thuenauer
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Alessia Landi
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Katja Kühn
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Samuel Juillot
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, Albertstraße 19, 79104 Freiburg, Germany
| | - Anne Imberty
- Centre de Recherches sur les Macromolécules Végétales, UPR5301 CNRS and University of Grenoble Alpes, BP53, 38041 Grenoble cédex 09, France
| | - Josef Madl
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Thorsten Eierhoff
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Winfried Römer
- Faculty of Biology, Schänzlestraße 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraße 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, Albertstraße 19, 79104 Freiburg, Germany.
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Suraju MO, Lalinde-Barnes S, Sanamvenkata S, Esmaeili M, Shishodia S, Rosenzweig JA. The effects of indoor and outdoor dust exposure on the growth, sensitivity to oxidative-stress, and biofilm production of three opportunistic bacterial pathogens. Sci Total Environ 2015; 538:949-958. [PMID: 26363607 DOI: 10.1016/j.scitotenv.2015.08.063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 08/09/2015] [Accepted: 08/12/2015] [Indexed: 06/05/2023]
Abstract
Within the last decade, many studies have highlighted the radical changes in the components of indoor and outdoor dust. For example, agents like automobile emitted platinum group elements and different kinds of organic phthalates and esters have been reported to be accumulating in the biosphere. Humans consistently face dermal, respiratory, and dietary exposures to these particles while indoors and outdoors. In fact, dust particulate matter has been associated with close to 500,000 deaths per year in Europe and about 200,000 deaths per year in the United States. To date, there has been limited examination of the physiological impact of indoor and outdoor dust exposure on normal flora microbes. In this study, the effect of indoor- and outdoor-dust exposure on three opportunistic bacterial species (Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa) was assessed. Specifically, bacterial growth, oxidative stress resistance, and biofilm production were measured following indoor- and outdoor-dust exposures. Studies were conducted in nutritionally-rich and -poor environments typically encountered by bacteria. Surprisingly, indoor-dust (200μg/mL), enhanced the growth of all three bacterial species in nutrient-poor conditions, but slowed growth in nutrient-rich conditions. In nutrient-rich medium, 100μg/mL exposure of either indoor- or outdoor-dust resulted in significantly reduced oxidative stress resistance in E. coli. Most interestingly, dust (indoor and outdoor), either in nutrient-rich or -poor conditions, significantly increased biofilm production in all three bacterial species. These data suggest that indoor and outdoor dust, can modify opportunistic bacteria through altering growth, sensitivity to oxidative stress, and their virulence potential through enhanced biofilm formation.
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Affiliation(s)
- Mohammed O Suraju
- Department of Biology, Texas Southern University, 3100, Cleburne St, Houston, TX 77099, United States
| | - Sloan Lalinde-Barnes
- DeBakey High School for Health Professions, 3100 Shenandoah St, Houston, TX 77021, United States
| | - Sachindra Sanamvenkata
- DeBakey High School for Health Professions, 3100 Shenandoah St, Houston, TX 77021, United States
| | - Mahsa Esmaeili
- Department of Environmental and Interdisciplinary Sciences, Texas Southern University, Houston, TX 77099, United States
| | - Shishir Shishodia
- Department of Biology, Texas Southern University, 3100, Cleburne St, Houston, TX 77099, United States
| | - Jason A Rosenzweig
- Department of Biology, Texas Southern University, 3100, Cleburne St, Houston, TX 77099, United States; Department of Environmental and Interdisciplinary Sciences, Texas Southern University, Houston, TX 77099, United States.
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Mocca B, Yin D, Gao Y, Wang W. Moraxella catarrhalis-produced nitric oxide has dual roles in pathogenicity and clearance of infection in bacterial-host cell co-cultures. Nitric Oxide 2015; 51:52-62. [PMID: 26537639 DOI: 10.1016/j.niox.2015.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 09/30/2015] [Accepted: 10/26/2015] [Indexed: 11/26/2022]
Abstract
In humans, the free radical nitric oxide (NO) is a concentration-dependent multifunctional signaling or toxic molecule that modulates various physiological and pathological processes, and innate immunity against bacterial infections. Because the expression of bacterial genes encoding nitrite reductase (AniA) and NO reductase (NorB) is highly upregulated in biofilms in vitro, it is important to investigate whether bacterial NO-metabolism might subvert host NO signaling and play pathogenic roles during infection. The Moraxella catarrhalis AniA and NorB directly function in production and reduction of NO. Using M. catarrhalis-human bronchial epithelial cell (HBEC) co-cultures, we recently reported AniA/nitrite-dependent cytotoxic effects on HBECs, including altered protein profiles of HBECs and induced HBEC apoptosis, suggesting bacterial nitrite reduction likely dysregulates host cell gene expression. To further clarify whether nitrite reduction-derived NO or nitrite-dependent stimulation of bacterial growth was responsible for adverse effects on HBECs, we monitored bacterial nitrite reduction, levels of NO in co-cultures and resulted dynamic effects on HBEC proliferation and bacterial viability. This study demonstrated that M. catarrhalis nitrite reduction-derived NO was responsible for observed adverse effects on HBECs at mid-to-late stages of infection. More importantly, our data showed that while nitrite promoted bacterial growth and biofilm formation at early hours of infection, nitrite reduction-derived NO was toxic towards M. catarrhalis in maturing biofilms, suggesting nitrite reduction-derived NO might be a possible dualistic mechanism by which M. catarrhalis promotes diseases and spontaneous resolutions.
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Affiliation(s)
- Brian Mocca
- Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993-0002, USA
| | - Dandan Yin
- Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993-0002, USA
| | - Yamei Gao
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993-0002, USA
| | - Wei Wang
- Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993-0002, USA.
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Teramoto H, Kumeda Y, Yokoigawa K, Hosomi K, Kozaki S, Mukamoto M, Kohda T. Genotyping and characterisation of the secretory lipolytic enzymes of Malassezia pachydermatis isolates collected from dogs. Vet Rec Open 2015; 2:e000124. [PMID: 26392911 PMCID: PMC4567167 DOI: 10.1136/vetreco-2015-000124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 06/20/2015] [Accepted: 07/16/2015] [Indexed: 11/12/2022] Open
Abstract
Introduction Malassezia species are commensals of normal skin microbial flora of humans and animals. These may become pathogenic under certain conditions such as those associated with atopic dermatitis or otitis externa in dogs. Material and methods Isolates of Malassezia pachydermatis were obtained from 27 dogs with healthy external ears and 32 dogs with otitis externa. Isolates were characterised on the basis of their first internal transcribed spacer (ITS) and internal spacer 1 (IGS1) sequences. Their extracellular lipase and phospholipase activity were also analysed. Three types of phospholipase inhibitor were used to identify the subclasses of phospholipase associated with otitis externa. Results The clinical isolates were classified into three ITS and three IGS1 sequence types. No significant differences in pathogenicity were detected among the ITS or IGS1 genotypes, and all of the isolates exhibited similar levels of lipase activity. The isolates derived from the dogs with otitis externa showed significantly higher phospholipase activity than those obtained from the dogs with healthy external ears. A phospholipase D inhibitor reduced the phospholipase activity of the isolates obtained from the dogs with otitis externa. Conclusions This study did not show any significant differences in pathogenicity among the ITS or IGS1 genotypes but does suggest that phospholipase D might be one of the virulence factors involved in the inflammation of the external ear caused by M. pachydermatis.
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Affiliation(s)
- Hideshi Teramoto
- Shinchitose Animal Clinic , Hokkaido , Japan ; Department of Veterinary Science , Graduate School of Life and Environmental Sciences, Osaka Prefecture University , Osaka , Japan
| | - Yuko Kumeda
- Osaka Prefectural Institute of Public Health , Osaka , Japan
| | - Kumio Yokoigawa
- Faculty of Integrated Arts and Sciences, Department of Civil and Environmental Studies , University of Tokushima , Tokushima , Japan
| | - Koji Hosomi
- Department of Veterinary Science , Graduate School of Life and Environmental Sciences, Osaka Prefecture University , Osaka , Japan
| | - Shunji Kozaki
- Department of Veterinary Science , Graduate School of Life and Environmental Sciences, Osaka Prefecture University , Osaka , Japan
| | - Masafumi Mukamoto
- Department of Veterinary Science , Graduate School of Life and Environmental Sciences, Osaka Prefecture University , Osaka , Japan
| | - Tomoko Kohda
- Department of Veterinary Science , Graduate School of Life and Environmental Sciences, Osaka Prefecture University , Osaka , Japan
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Bárcena-Uribarri I, Benz R, Winterhalter M, Zakharian E, Balashova N. Pore forming activity of the potent RTX-toxin produced by pediatric pathogen Kingella kingae: Characterization and comparison to other RTX-family members. Biochim Biophys Acta 2015; 1848:1536-44. [PMID: 25858109 DOI: 10.1016/j.bbamem.2015.03.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 03/25/2015] [Accepted: 03/30/2015] [Indexed: 12/18/2022]
Abstract
Pediatric septic arthritis in patients under age of four is frequently caused by the oral Gram-negative bacterium Kingella kingae. This organism may be responsible for a severe form of infective endocarditis in otherwise healthy children and adults. A major virulence factor of K. kingae is RtxA, a toxin that belongs to the RTX (Repeats-in-ToXin) group of secreted pore forming toxins. To understand the RtxA effects on host cell membranes, the toxin activity was studied using planar lipid bilayers. K. kingae strain PYKK081 and its isogenic RtxA-deficient strain, KKNB100, were tested for their ability to form pores in artificial membranes of asolectin/n-decane. RtxA, purified from PYKK081, was able to rapidly form pores with an apparent diameter of 1.9nm as measured by the partition of nonelectrolytes in the pores. The RtxA channels are cation-selective and showed strong voltage-dependent gating. In contrast to supernatants of PYKK081, those of KKNB100 did not show any pore forming activity. We concluded that RtxA toxin is the only secreted protein from K. kingae forming large channels in host cell membranes where it induces cation flux leading to programmed cell death. Furthermore, our findings suggested that the planar lipid bilayer technique can effectively be used to test possible inhibitors of RTX toxin activity and to investigate the mechanism of the toxin binding to the membrane.
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Affiliation(s)
| | - Roland Benz
- Department of Life Science and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Mathias Winterhalter
- Department of Life Science and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Eleonora Zakharian
- Department of Cancer Biology & Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA
| | - Nataliya Balashova
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Abstract
During the infectious process, bacterial pathogens are subject to changes in environmental conditions such as nutrient availability, immune response challenges, bacterial density and physical contacts with targeted host cells. These conditions occur in the colonized organs, in diverse regions within infected tissues or even at the subcellular level for intracellular pathogens. Integration of environmental cues leads to measurable biological responses in the bacterium required for adaptation. Recent progress in technology enabled the study of bacterial adaptation in situ using genetically encoded reporters that allow single cell analysis or whole body imaging based on fluorescent proteins, alternative fluorescent assays or luciferases. This review presents a historical perspective and technical details on the methods used to develop transcriptional reporters, protein-protein interaction assays and secretion detection assays to study pathogenic bacteria adaptation in situ. Finally, studies published in the last 5 years on gram positive and gram negative bacterial adaptation to the host during infection are discussed. However, the methods described here could easily be extended to study complex microbial communities within host tissue and in the environment.
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Affiliation(s)
- F-X Campbell-Valois
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 25-28 rue du Docteur-Roux, 75724 Paris, France; INSERM, U786, 75015 Paris, France
| | - Philippe J Sansonetti
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 25-28 rue du Docteur-Roux, 75724 Paris, France; INSERM, U786, 75015 Paris, France; Collège de France, Chaire de Microbiologie et Maladies infectieuses, 11 Place Marcelin Berthelot, 75005 Paris, France.
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Li X, Zhou X, Li Y, Li J, Privratsky B, Ye Y, Wu E, Gao H, Huang C, Wu M. Lyn regulates inflammatory responses in Klebsiella pneumoniae infection via the p38/NF-κB pathway. Eur J Immunol 2014; 44:763-73. [PMID: 24338528 PMCID: PMC4103995 DOI: 10.1002/eji.201343972] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/07/2013] [Accepted: 11/11/2013] [Indexed: 02/05/2023]
Abstract
Klebsiella pneumoniae (Kp) is one of the most common pathogens in nosocomial infections and is becoming increasingly multidrug resistant. However, the underlying molecular pathogenesis of this bacterium remains elusive, limiting the therapeutic options. Understanding the mechanism of its pathogenesis may facilitate the development of anti-bacterial therapeutics. Here, we show that Lyn, a pleiotropic Src tyrosine kinase, is involved in host defense against Kp by regulating phagocytosis process and simultaneously downregulating inflammatory responses. Using acute infection mouse models, we observed that lyn(-/-) mice were more susceptible to Kp with increased mortality and severe lung injury compared with WT mice. Kp infected-lyn(-/-) mice exhibited elevated inflammatory cytokines (IL-6 and TNF-α), and increased superoxide in the lung and other organs. In addition, the phosphorylation of p38 and NF-κB p65 subunit increased markedly in response to Kp infection in lyn(-/-) mice. We also demonstrated that the translocation of p65 from cytoplasm to nuclei increased in cultured murine lung epithelial cells by Lyn siRNA knockdown. Furthermore, lipid rafts clustered with activated Lyn and accumulated in the site of Kp invasion. Taken together, these findings revealed that Lyn may participate in host defense against Kp infection through the negative modulation of inflammatory cytokines.
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Affiliation(s)
- Xuefeng Li
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, P. R. China
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
| | - Xikun Zhou
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, P. R. China
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
| | - Yi Li
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, P. R. China
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
| | - Jiaxin Li
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
| | - Breanna Privratsky
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
| | - Yan Ye
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
| | - Erxi Wu
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, USA
| | - Hongwei Gao
- Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative & Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Canhua Huang
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, P. R. China
| | - Min Wu
- Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, North Dakota 58203-9037, USA
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Burkinshaw BJ, Strynadka NCJ. Assembly and structure of the T3SS. Biochim Biophys Acta 2014; 1843:1649-63. [PMID: 24512838 DOI: 10.1016/j.bbamcr.2014.01.035] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/27/2014] [Accepted: 01/29/2014] [Indexed: 02/06/2023]
Abstract
The Type III Secretion System (T3SS) is a multi-mega Dalton apparatus assembled from more than twenty components and is found in many species of animal and plant bacterial pathogens. The T3SS creates a contiguous channel through the bacterial and host membranes, allowing injection of specialized bacterial effector proteins directly to the host cell. In this review, we discuss our current understanding of T3SS assembly and structure, as well as highlight structurally characterized Salmonella effectors. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Brianne J Burkinshaw
- Department of Biochemistry and Molecular Biology, Center for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology, Center for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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Santos AJM, Meinecke M, Fessler MB, Holden DW, Boucrot E. Preferential invasion of mitotic cells by Salmonella reveals that cell surface cholesterol is maximal during metaphase. J Cell Sci 2013; 126:2990-6. [PMID: 23687374 DOI: 10.1242/jcs.115253] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell surface-exposed cholesterol is crucial for cell attachment and invasion of many viruses and bacteria, including the bacterium Salmonella, which causes typhoid fever and gastroenteritis. Using flow cytometry and 3D confocal fluorescence microscopy, we found that mitotic cells, although representing only 1-4% of an exponentially growing population, were much more efficiently targeted for invasion by Salmonella. This targeting was not dependent on the spherical shape of mitotic cells, but was instead SipB and cholesterol dependent. Thus, we measured the levels of plasma membrane and cell surface cholesterol throughout the cell cycle using, respectively, brief staining with filipin and a fluorescent ester of polyethylene glycol-cholesterol that cannot flip through the plasma membrane, and found that both were maximal during mitosis. This increase was due not only to the rise in global cell cholesterol levels along the cell cycle but also to a transient loss in cholesterol asymmetry at the plasma membrane during mitosis. We measured that cholesterol, but not phosphatidylserine, changed from a ∼2080 outerinner leaflet repartition during interphase to ∼5050 during metaphase, suggesting this was specific to cholesterol and not due to a broad change of lipid asymmetry during metaphase. This explains the increase in outer surface levels that make dividing cells more susceptible to Salmonella invasion and perhaps to other viruses and bacteria entering cells in a cholesterol-dependent manner. The change in cholesterol partitioning also favoured the recruitment of activated ERM (Ezrin, Radixin, Moesin) proteins at the plasma membrane and thus supported mitotic cell rounding.
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Affiliation(s)
- António J M Santos
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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Leiba J, Syson K, Baronian G, Zanella-Cléon I, Kalscheuer R, Kremer L, Bornemann S, Molle V. Mycobacterium tuberculosis maltosyltransferase GlgE, a genetically validated antituberculosis target, is negatively regulated by Ser/Thr phosphorylation. J Biol Chem 2013; 288:16546-16556. [PMID: 23609448 DOI: 10.1074/jbc.m112.398503] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GlgE is a maltosyltransferase involved in the biosynthesis of α-glucans that has been genetically validated as a potential therapeutic target against Mycobacterium tuberculosis. Despite also making α-glucan, the GlgC/GlgA glycogen pathway is distinct and allosterically regulated. We have used a combination of genetics and biochemistry to establish how the GlgE pathway is regulated. M. tuberculosis GlgE was phosphorylated specifically by the Ser/Thr protein kinase PknB in vitro on one serine and six threonine residues. Furthermore, GlgE was phosphorylated in vivo when expressed in Mycobacterium bovis bacillus Calmette-Guérin (BCG) but not when all seven phosphorylation sites were replaced by Ala residues. The GlgE orthologues from Mycobacterium smegmatis and Streptomyces coelicolor were phosphorylated by the corresponding PknB orthologues in vitro, implying that the phosphorylation of GlgE is widespread among actinomycetes. PknB-dependent phosphorylation of GlgE led to a 2 orders of magnitude reduction in catalytic efficiency in vitro. The activities of phosphoablative and phosphomimetic GlgE derivatives, where each phosphorylation site was substituted with either Ala or Asp residues, respectively, correlated with negative phosphoregulation. Complementation studies of a M. smegmatis glgE mutant strain with these GlgE derivatives, together with both classical and chemical forward genetics, were consistent with flux through the GlgE pathway being correlated with GlgE activity. We conclude that the GlgE pathway appears to be negatively regulated in actinomycetes through the phosphorylation of GlgE by PknB, a mechanism distinct from that known in the classical glycogen pathway. Thus, these findings open new opportunities to target the GlgE pathway therapeutically.
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Affiliation(s)
- Jade Leiba
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier II et I, CNRS, UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Karl Syson
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Grégory Baronian
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier II et I, CNRS, UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Isabelle Zanella-Cléon
- Institut de Biologie et Chimie des Protéines (IBCP UMR 5086), CNRS, Université Lyon1, IFR128 BioSciences, Lyon Gerland, 7 passage du Vercors, 69367 Lyon Cedex 07, France
| | - Rainer Kalscheuer
- Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Laurent Kremer
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier II et I, CNRS, UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France; INSERM, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Stephen Bornemann
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
| | - Virginie Molle
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier II et I, CNRS, UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France.
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Annapoorani A, Jabbar AKKA, Musthafa SKS, Pandian SK, Ravi AV. Inhibition of Quorum Sensing Mediated Virulence Factors Production in Urinary Pathogen Serratia marcescens PS1 by Marine Sponges. Indian J Microbiol 2012; 52:160-6. [PMID: 23729876 DOI: 10.1007/s12088-012-0272-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 04/27/2012] [Indexed: 10/28/2022] Open
Abstract
The focal intent of this study was to find out an alternative strategy for the antibiotic usage against bacterial infections. The quorum sensing inhibitory (QSI) activity of marine sponges collected from Palk Bay, India was evaluated against acyl homoserine lactone (AHL) mediated violacein production in Chromobacterium violaceum (ATCC 12472), CV026 and virulence gene expressions in clinical isolate Serratia marcescens PS1. Out of 29 marine sponges tested, the methanol extracts of Aphrocallistes bocagei (TS 8), Haliclona (Gellius) megastoma (TS 25) and Clathria atrasanguinea (TS 27) inhibited the AHL mediated violacein production in C. violaceum (ATCC 12472) and CV026. Further, these sponge extracts inhibited the AHL dependent prodigiosin pigment, virulence enzymes such as protease, hemolysin production and biofilm formation in S. marcescens PS1. However, these sponge extracts were not inhibitory to bacterial growth, which reveals the fact that the QSI activity of these extracts was not related to static or killing effects on bacteria. Based on the obtained results, it is envisaged that the marine sponges could pave the way to prevent quorum sensing (QS) mediated bacterial infections.
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Affiliation(s)
- Angusamy Annapoorani
- Department of Biotechnology, Alagappa University, Karaikudi, 630 003 Tamil Nadu India
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Lei B. Benfang Lei’s research on heme acquisition in Gram-positive pathogens and bacterial pathogenesis. World J Biol Chem 2010; 1:286-90. [PMID: 21537486 PMCID: PMC3083973 DOI: 10.4331/wjbc.v1.i9.286] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 08/20/2010] [Accepted: 08/27/2010] [Indexed: 02/05/2023] Open
Abstract
Benfang Lei’s laboratory conducts research on pathogenesis of human pathogen Group A Streptococcus (GAS) and horse pathogen Streptococcus equi (S. equi). His current research focuses on heme acquisition in Gram-positive pathogens and molecular mechanism of GAS and S. equi pathogenesis. Heme is an important source of essential iron for bacterial pathogens. Benfang Lei and colleagues identified the first cell surface heme-binding protein in Gram-positive pathogens and the heme acquisition system in GAS, demonstrated direct heme transfer from one protein to another, demonstrated an experimental pathway of heme acquisition by the Staphylococcus aureus Isd system, elucidated the activated heme transfer mechanism, and obtained evidence for a chemical mechanism of direct axial ligand displacement during the Shp-to-HtsA heme transfer reaction. These findings have considerably contributed to the progress that has been made over recent years in understanding the heme acquisition process in Gram-positive pathogens. Pathogenesis of GAS is mediated by an abundance of extracellular proteins, and pathogenic role and functional mechanism are not known for many of these virulence factors. Lei laboratory identified a secreted protein of GAS as a CovRS-regulated virulence factor that is a protective antigen and is critical for GAS spreading in the skin and systemic dissemination. These studies may lead to development of novel strategies to prevent and treat GAS infections.
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Affiliation(s)
- Benfang Lei
- Benfang Lei, Department of Veterinary Molecular Biology, Montana State University, 960 Technology Blvd, Bozeman, MT 59717, United States
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