1
|
Lucidi M, Visaggio D, Migliaccio A, Capecchi G, Visca P, Imperi F, Zarrilli R. Pathogenicity and virulence of Acinetobacter baumannii: Factors contributing to the fitness in healthcare settings and the infected host. Virulence 2024; 15:2289769. [PMID: 38054753 PMCID: PMC10732645 DOI: 10.1080/21505594.2023.2289769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 11/27/2023] [Indexed: 12/07/2023] Open
Abstract
Acinetobacter baumannii is a common cause of healthcare-associated infections and hospital outbreaks, particularly in intensive care units. Much of the success of A. baumannii relies on its genomic plasticity, which allows rapid adaptation to adversity and stress. The capacity to acquire novel antibiotic resistance determinants and the tolerance to stresses encountered in the hospital environment promote A. baumannii spread among patients and long-term contamination of the healthcare setting. This review explores virulence factors and physiological traits contributing to A. baumannii infection and adaptation to the hospital environment. Several cell-associated and secreted virulence factors involved in A. baumannii biofilm formation, cell adhesion, invasion, and persistence in the host, as well as resistance to xeric stress imposed by the healthcare settings, are illustrated to give reasons for the success of A. baumannii as a hospital pathogen.
Collapse
Affiliation(s)
- Massimiliano Lucidi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | | | | | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, Naples, Italy
| |
Collapse
|
2
|
Han ML, Alsaadi Y, Zhao J, Zhu Y, Lu J, Jiang X, Ma W, Patil NA, Dunstan RA, Le Brun AP, Wickremasinghe H, Hu X, Wu Y, Yu HH, Wang J, Barlow CK, Bergen PJ, Shen HH, Lithgow T, Creek DJ, Velkov T, Li J. Arginine catabolism is essential to polymyxin dependence in Acinetobacter baumannii. Cell Rep 2024; 43:114410. [PMID: 38923457 DOI: 10.1016/j.celrep.2024.114410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 02/03/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
Polymyxins are often the only effective antibiotics against the "Critical" pathogen Acinetobacter baumannii. Worryingly, highly polymyxin-resistant A. baumannii displaying dependence on polymyxins has emerged in the clinic, leading to diagnosis and treatment failures. Here, we report that arginine metabolism is essential for polymyxin-dependent A. baumannii. Specifically, the arginine degradation pathway was significantly altered in polymyxin-dependent strains compared to wild-type strains, with critical metabolites (e.g., L-arginine and L-glutamate) severely depleted and expression of the astABCDE operon significantly increased. Supplementation of arginine increased bacterial metabolic activity and suppressed polymyxin dependence. Deletion of astA, the first gene in the arginine degradation pathway, decreased phosphatidylglycerol and increased phosphatidylethanolamine levels in the outer membrane, thereby reducing the interaction with polymyxins. This study elucidates the molecular mechanism by which arginine metabolism impacts polymyxin dependence in A. baumannii, underscoring its critical role in improving diagnosis and treatment of life-threatening infections caused by "undetectable" polymyxin-dependent A. baumannii.
Collapse
Affiliation(s)
- Mei-Ling Han
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia.
| | - Yasser Alsaadi
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Jinxin Zhao
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Yan Zhu
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Jing Lu
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Xukai Jiang
- National Glycoengineering Research Centre, Shandong University, Qingdao 266237, China
| | - Wendong Ma
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Nitin A Patil
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Rhys A Dunstan
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Hasini Wickremasinghe
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Xiaohan Hu
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Yimin Wu
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Heidi H Yu
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Jiping Wang
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Christopher K Barlow
- Monash Proteomics and Metabolomics Facility, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Phillip J Bergen
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Hsin-Hui Shen
- Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Trevor Lithgow
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia
| | - Darren J Creek
- Monash Proteomics and Metabolomics Facility, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Tony Velkov
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Jian Li
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; Centre to Impact AMR, Monash University, Clayton, VIC 3800, Australia.
| |
Collapse
|
3
|
Cobe BL, Dey S, Minasov G, Inniss N, Satchell KJF, Cianciotto NP. Bactericidal effectors of the Stenotrophomonas maltophilia type IV secretion system: functional definition of the nuclease TfdA and structural determination of TfcB. mBio 2024; 15:e0119824. [PMID: 38832773 PMCID: PMC11253643 DOI: 10.1128/mbio.01198-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 04/28/2024] [Indexed: 06/05/2024] Open
Abstract
Stenotrophomonas maltophilia expresses a type IV protein secretion system (T4SS) that promotes contact-dependent killing of other bacteria and does so partly by secreting the effector TfcB. Here, we report the structure of TfcB, comprising an N-terminal domain similar to the catalytic domain of glycosyl hydrolase (GH-19) chitinases and a C-terminal domain for recognition and translocation by the T4SS. Utilizing a two-hybrid assay to measure effector interactions with the T4SS coupling protein VirD4, we documented the existence of five more T4SS substrates. One of these was protein 20845, an annotated nuclease. A S. maltophilia mutant lacking the gene for 20845 was impaired for killing Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Moreover, the cloned 20845 gene conferred robust toxicity, with the recombinant E. coli being rescued when 20845 was co-expressed with its cognate immunity protein. The 20845 effector was an 899 amino-acid protein, comprised of a GHH-nuclease domain in its N-terminus, a large central region of indeterminant function, and a C-terminus for secretion. Engineered variants of the 20845 gene that had mutations in the predicted catalytic site did not impede E. coli, indicating that the antibacterial effect of 20845 involves its nuclease activity. Using flow cytometry with DNA staining, we determined that 20845, but not its mutant variants, confers a loss in DNA content of target bacteria. Database searches revealed that uncharacterized homologs of 20845 occur within a range of bacteria. These data indicate that the S. maltophilia T4SS promotes interbacterial competition through the action of multiple toxic effectors, including a potent, novel DNase.IMPORTANCEStenotrophomonas maltophilia is a multi-drug-resistant, Gram-negative bacterium that is an emerging pathogen of humans. Patients with cystic fibrosis are particularly susceptible to S. maltophilia infection. In hospital water systems and various types of infections, S. maltophilia co-exists with other bacteria, including other pathogens such as Pseudomonas aeruginosa. We previously demonstrated that S. maltophilia has a functional VirB/D4 type VI protein secretion system (T4SS) that promotes contact-dependent killing of other bacteria. Since most work on antibacterial systems involves the type VI secretion system, this observation remains noteworthy. Moreover, S. maltophilia currently stands alone as a model for a human pathogen expressing an antibacterial T4SS. Using biochemical, genetic, and cell biological approaches, we now report both the discovery of a novel antibacterial nuclease (TfdA) and the first structural determination of a bactericidal T4SS effector (TfcB).
Collapse
Affiliation(s)
- Brandi L. Cobe
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Supratim Dey
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Center for Structural Biology of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - George Minasov
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Center for Structural Biology of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nicole Inniss
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Center for Structural Biology of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Karla J. F. Satchell
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Center for Structural Biology of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nicholas P. Cianciotto
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| |
Collapse
|
4
|
Casiano González A, Pacheco Villanueva A, Castro-Alarcón N, Méndez J, Oropeza R, Martínez-Santos VI. A novel chaperone-effector-immunity system identified in uropathogenic Escherichia coli UMN026. PeerJ 2024; 12:e17336. [PMID: 38784397 PMCID: PMC11114119 DOI: 10.7717/peerj.17336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 04/15/2024] [Indexed: 05/25/2024] Open
Abstract
Background Urinary tract infections (UTIs) are very common worldwide. According to their symptomatology, these infections are classified as pyelonephritis, cystitis, or asymptomatic bacteriuria (AB). Approximately 75-95% of UTIs are caused by uropathogenic Escherichia coli (UPEC), which is an extraintestinal bacterium that possesses virulence factors for bacterial adherence and invasion in the urinary tract. In addition, UPEC possesses type 6 secretion systems (T6SS) as virulence mechanisms that can participate in bacterial competition and in bacterial pathogenicity. UPEC UMN026 carries three genes, namely, ECUMN_0231, ECUMN_0232, and ECUMN_0233, which encode three uncharacterized proteins related to the T6SS that are conserved in strains from phylogroups B2 and D and have been proposed as biomarkers of UTIs. Aim To analyze the frequency of the ECUMN_0231, ECUMN_0232, ECUMN_0233, and vgrG genes in UTI isolates, as well as their expression in Luria Bertani (LB) medium and urine; to determine whether these genes are related to UTI symptoms or bacterial competence and to identify functional domains on the putative proteins. Methods The frequency of the ECUMN and vgrG genes in 99 clinical isolates from UPEC was determined by endpoint PCR. The relationship between gene presence and UTI symptomatology was determined using the chi2 test, with p < 0.05 considered to indicate statistical significance. The expression of the three ECUMN genes and vgrG was analyzed by RT-PCR. The antibacterial activity of strain UMN026 was determined by bacterial competence assays. The identification of functional domains and the docking were performed using bioinformatic tools. Results The ECUMN genes are conserved in 33.3% of clinical isolates from patients with symptomatic and asymptomatic UTIs and have no relationship with UTI symptomatology. Of the ECUMN+ isolates, only five (15.15%, 5/33) had the three ECUMN and vgrG genes. These genes were expressed in LB broth and urine in UPEC UMN026 but not in all the clinical isolates. Strain UMN026 had antibacterial activity against UPEC clinical isolate 4014 (ECUMN-) and E. faecalis but not against isolate 4012 (ECUMN+). Bioinformatics analysis suggested that the ECUMN genes encode a chaperone/effector/immunity system. Conclusions The ECUMN genes are conserved in clinical isolates from symptomatic and asymptomatic patients and are not related to UTI symptoms. However, these genes encode a putative chaperone/effector/immunity system that seems to be involved in the antibacterial activity of strain UMN026.
Collapse
Affiliation(s)
- América Casiano González
- Microbiology Research Laboratory, Faculty of Chemical Biological Sciences, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico
| | - Arantxa Pacheco Villanueva
- Microbiology Research Laboratory, Faculty of Chemical Biological Sciences, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico
| | - Natividad Castro-Alarcón
- Microbiology Research Laboratory, Faculty of Chemical Biological Sciences, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico
| | - Julio Méndez
- Department of Molecular Microbiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Ricardo Oropeza
- Department of Molecular Microbiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | | |
Collapse
|
5
|
Li Y, Jv M, Zhuang Y, Zhao X, Hu X. A hypervirulent Acinetobacter baumannii strain has robust anti-phagocytosis ability. BMC Microbiol 2024; 24:106. [PMID: 38561652 PMCID: PMC10983618 DOI: 10.1186/s12866-024-03264-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 03/17/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Acinetobacter baumannii (A. baumannii) is associated with both hospital-acquired infections (HAP) and community-acquired pneumonia (CAP). In this study, we present a novel CAP-associated A. baumannii (CAP-AB) strain causing severe pneumonia in an afore healthy male patient without underlying conditions. Subsequently, we investigated the pathogenicity and immunogenicity of this CAP-AB strain using a mice pneumonia model. RESULTS A 58-year-old male patient with no underlying conditions experienced worsening symptoms of a productive cough, sputum, and fever that developed acutely, in just 24 h. The diagnosis was severe community-acquired pneumonia (CAP) and type-1 respiratory failure. An A. baumannii strain was isolated from his sputum and blood cultures. To gain a deeper understanding of the rapid progression of its pathology, we utilized the CAP-associated A. baumannii strain YC128, a previously obtained hospital-acquired pneumonia A. baumannii (HAP-AB) strain YC156, and a highly virulent A. baumannii control strain LAC-4 to construct a mouse pneumonia model, and subsequently compared the mortality rate of the three groups. Following inoculation with 107 CFU of A. baumannii, the mortality rate for the YC128, LAC-4, and YC156 groups was 60% (6/10), 30% (3/10), and 0%, respectively. The bacterial burden within the pulmonary, liver, and spleen tissues of mice in the YC128 group was significantly higher than that of the YC156 group, and slightly higher than that of the LAC-4 group. Pathological analysis of lung tissue using HE-staining revealed that the inflammatory pathological changes in mice from the YC128 group were significantly more severe than those in the YC156 group. Additionally, CT scan images displayed more pronounced inflammation in the lungs of mice from the YC128 group compared to the YC156 group. Local levels of cytokines/chemokines such as IL-1β, IL-6, TNF-α, and CXCL1 were assessed via RT-qPCR in lung tissues. In comparison with the YC156 strain, the highly virulent YC128 strain induced the expression of proinflammatory cytokines more rapidly and severely. Furthermore, we examined the in vitro anti-phagocytosis ability of YC128 and YC156 strains against mice peritoneal macrophages, revealing that the highly virulent YC128 isolate displayed greater resistance to macrophage uptake in contrast to YC156. Results from Whole Genome Sequencing (WGS) indicated that YC128 harbored a complete type VI secretion system (T6SS) gene cluster, while YC156 lacked the majority of genes within the T6SS gene cluster. The other virulence-related genes exhibited minimal differences between YC128 and YC156. Drawing from previous studies, we postulated that the T6SS is linked to the hypervirulence and robust anti-phagocytic ability of YC128. CONCLUSIONS This article reports on the isolation of a novel hypervirulent CAP-AB strain, YC128, from a severe CAP patient. The results demonstrate that this CAP-AB strain, YC128, is capable of inducing fatal pneumonia and extrapulmonary dissemination in a mouse pneumonia model. Moreover, this highly virulent CAP-AB strain exhibits significantly stronger anti-phagocytic abilities compared to the HAP-AB YC156 strain. Genome sequencing comparisons reveal that the heightened hypervirulence and enhanced anti-phagocytosis abilities observed in YC128 may be attributed to the presence of the T6SS.
Collapse
Affiliation(s)
- Yan Li
- Division of Infectious Diseases, Yichun People's Hospital, Yichun, Jiangxi Province, China
| | - Mohan Jv
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Yuan Zhuang
- Department of Infectious Diseases, People's Hospital of Rizhao, Ri Zhao, Shandong Province, China
| | - Xu Zhao
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China.
- Department of Infectious Diseases, Huashan Hospital Fujian Campus, Fudan University, Fuzhou, Fujian Province, China.
| | - Xiaoxiong Hu
- Division of Infectious Diseases, Yichun People's Hospital, Yichun, Jiangxi Province, China.
| |
Collapse
|
6
|
Santos MNM, Pintor KL, Hsieh PY, Cheung YW, Sung LK, Shih YL, Lai EM. Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors. Front Microbiol 2024; 15:1351590. [PMID: 38426053 PMCID: PMC10902643 DOI: 10.3389/fmicb.2024.1351590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/22/2024] [Indexed: 03/02/2024] Open
Abstract
The type VI secretion system (T6SS) assembles into a contractile nanomachine to inject effectors across bacterial membranes for secretion. The Agrobacterium tumefaciens species complex is a group of soil inhabitants and phytopathogens that deploys T6SS as an antibacterial weapon against bacterial competitors at both inter-species and intra-species levels. The A. tumefaciens strain 1D1609 genome encodes one main T6SS gene cluster and four vrgG genes (i.e., vgrGa-d), each encoding a spike protein as an effector carrier. A previous study reported that vgrGa-associated gene 2, named v2a, encodes a His-Me finger nuclease toxin (also named HNH/ENDO VII nuclease), contributing to DNase-mediated antibacterial activity. However, the functions and roles of other putative effectors remain unknown. In this study, we identified vgrGc-associated gene 2 (v2c) that encodes another His-Me finger nuclease but with a distinct Serine Histidine Histidine (SHH) motif that differs from the AHH motif of V2a. We demonstrated that the ectopic expression of V2c caused growth inhibition, plasmid DNA degradation, and cell elongation in Escherichia coli using DNAse activity assay and fluorescence microscopy. The cognate immunity protein, V3c, neutralizes the DNase activity and rescues the phenotypes of growth inhibition and cell elongation. Ectopic expression of V2c DNase-inactive variants retains the cell elongation phenotype, while V2a induces cell elongation in a DNase-mediated manner. We also showed that the amino acids of conserved SHH and HNH motifs are responsible for the V2c DNase activity in vivo and in vitro. Notably, V2c also mediated the DNA degradation and cell elongation of the target cell in the context of interbacterial competition. Importantly, V2a and V2c exhibit different capacities against different bacterial species and function synergistically to exert stronger antibacterial activity against the soft rot phytopathogen, Dickeya dadantii.
Collapse
Affiliation(s)
- Mary Nia M. Santos
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
- Aquaculture Research and Development Division, Department of Agriculture-National Fisheries Research and Development Institute (DA-NFRDI), Manila, Philippines
| | | | - Pei-Yu Hsieh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yee-Wai Cheung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Li-Kang Sung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
| | - Yu-Ling Shih
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan
| |
Collapse
|
7
|
Li P, Zhang S, Wang J, Al-Shamiri MM, Luo K, Liu S, Mi P, Wu X, Liu H, Tian H, Han B, Lei J, Han S, Han L. The role of type VI secretion system genes in antibiotic resistance and virulence in Acinetobacter baumannii clinical isolates. Front Cell Infect Microbiol 2024; 14:1297818. [PMID: 38384301 PMCID: PMC10879597 DOI: 10.3389/fcimb.2024.1297818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
Introduction The type VI secretion system (T6SS) is a crucial virulence factor in the nosocomial pathogen Acinetobacter baumannii. However, its association with drug resistance is less well known. Notably, the roles that different T6SS components play in the process of antimicrobial resistance, as well as in virulence, have not been systematically revealed. Methods The importance of three representative T6SS core genes involved in the drug resistance and virulence of A. baumannii, namely, tssB, tssD (hcp), and tssM was elucidated. Results A higher ratio of the three core genes was detected in drug-resistant strains than in susceptible strains among our 114 A. baumannii clinical isolates. Upon deletion of tssB in AB795639, increased antimicrobial resistance to cefuroxime and ceftriaxone was observed, alongside reduced resistance to gentamicin. The ΔtssD mutant showed decreased resistance to ciprofloxacin, norfloxacin, ofloxacin, tetracycline, and doxycycline, but increased resistance to tobramycin and streptomycin. The tssM-lacking mutant showed an increased sensitivity to ofloxacin, polymyxin B, and furazolidone. In addition, a significant reduction in biofilm formation was observed only with the ΔtssM mutant. Moreover, the ΔtssM strain, followed by the ΔtssD mutant, showed decreased survival in human serum, with attenuated competition with Escherichia coli and impaired lethality in Galleria mellonella. Discussion The above results suggest that T6SS plays an important role, participating in the antibiotic resistance of A. baumannii, especially in terms of intrinsic resistance. Meanwhile, tssM and tssD contribute to bacterial virulence to a greater degree, with tssM being associated with greater importance.
Collapse
Affiliation(s)
- Pu Li
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Sirui Zhang
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Jingdan Wang
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Mona Mohamed Al-Shamiri
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Kai Luo
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Shuyan Liu
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Peng Mi
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
- Department of Laboratory Medicine, Shaanxi Provincial People’s Hospital, Xi’an, China
| | - Xiaokang Wu
- Department of Laboratory Medicine, the Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Haiping Liu
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
- Department of Laboratory Medicine, Xi’an Daxing Hospital, Xi’an, China
| | - Huohuan Tian
- Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Bei Han
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Jin’e Lei
- Department of Laboratory Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Shaoshan Han
- Department of Hepatobiliary Surgery, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Lei Han
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| |
Collapse
|
8
|
Morris FC, Jiang Y, Fu Y, Kostoulias X, Murray GL, Yu Y, Peleg AY. Lactate metabolism promotes in vivo fitness during Acinetobacter baumannii infection. FEMS Microbiol Lett 2024; 371:fnae032. [PMID: 38719540 PMCID: PMC11126152 DOI: 10.1093/femsle/fnae032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 04/30/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Acinetobacter baumannii is one of the most prevalent causes of nosocomial infections worldwide. However, a paucity of information exists regarding the connection between metabolic capacity and in vivo bacterial fitness. Elevated lactate is a key marker of severe sepsis. We have previously shown that the putative A. baumannii lactate permease gene, lldP, is upregulated during in vivo infection. Here, we confirm that lldP expression is upregulated in three A. baumannii strains during a mammalian systemic infection. Utilising a transposon mutant disrupted for lldP in the contemporary clinical strain AB5075-UW, and a complemented strain, we confirmed its role in the in vitro utilisation of l-(+)-lactate. Furthermore, disruption of the lactate metabolism pathway resulted in reduced bacterial fitness during an in vivo systemic murine competition assay. The disruption of lldP had no impact on the susceptibility of this strain to complement mediated killing by healthy human serum. However, growth in biologically relevant concentrations of lactate observed during severe sepsis, led to bacterial tolerance to killing by healthy human blood, a phenotype that was abolished in the lldP mutant. This study highlights the importance of the lactate metabolism pathway for survival and growth of A. baumannii during infection.
Collapse
Affiliation(s)
- Faye C Morris
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Centre to Impact AMR, Monash University, Clayton, Victoria 3800, Australia
| | - Yan Jiang
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang Province 310016, China
| | - Ying Fu
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang Province 310016, China
| | - Xenia Kostoulias
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Centre to Impact AMR, Monash University, Clayton, Victoria 3800, Australia
- Department of Infectious Diseases, The Alfred Hospital and School of Translational Medicine, Monash University, Melbourne, Victoria 3004, Australia
| | - Gerald L Murray
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Present Address; Royal Women's Hospital, Grattan Street, Parkville, Victoria 3052, Australia
| | - Yusong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang Province 310016, China
| | - Anton Y Peleg
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Centre to Impact AMR, Monash University, Clayton, Victoria 3800, Australia
- Department of Infectious Diseases, The Alfred Hospital and School of Translational Medicine, Monash University, Melbourne, Victoria 3004, Australia
| |
Collapse
|
9
|
Liu W, Li M, Cao S, Ishaq HM, Zhao H, Yang F, Liu L. The Biological and Regulatory Role of Type VI Secretion System of Klebsiella pneumoniae. Infect Drug Resist 2023; 16:6911-6922. [PMID: 37928603 PMCID: PMC10624183 DOI: 10.2147/idr.s426657] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/30/2023] [Indexed: 11/07/2023] Open
Abstract
Bacteria communicate with their surroundings through diverse secretory systems, and the recently discovered Type VI Secretion System (T6SS) has gained significant attention. Klebsiella pneumoniae (K. pneumoniae), an opportunistic pathogen known for causing severe infections in both hospital and animal settings, possesses this intriguing T6SS. This system equips K. pneumoniae with a formidable armory of protein-based weaponry, enabling the delivery of toxins into neighboring cells, thus granting a substantial competitive advantage. Remarkably, the T6SS has also been associated with K. pneumoniae's ability to form biofilms and acquire resistance against antibiotics. However, the precise effects of the T6SS on K. pneumoniae's functions remain inadequately studied, despite research efforts to understand the intricacies of these mechanisms. This comprehensive review aims to provide an overview of the current knowledge regarding the biological functions and regulatory mechanisms of the T6SS in K. pneumoniae.
Collapse
Affiliation(s)
- Wenke Liu
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Min Li
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Shiwen Cao
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Hafiz Muhammad Ishaq
- Faculty of Veterinary and Animal Sciences, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan
| | - Huajie Zhao
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Fan Yang
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Liang Liu
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| |
Collapse
|
10
|
Cavallo I, Oliva A, Pages R, Sivori F, Truglio M, Fabrizio G, Pasqua M, Pimpinelli F, Di Domenico EG. Acinetobacter baumannii in the critically ill: complex infections get complicated. Front Microbiol 2023; 14:1196774. [PMID: 37425994 PMCID: PMC10325864 DOI: 10.3389/fmicb.2023.1196774] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/05/2023] [Indexed: 07/11/2023] Open
Abstract
Acinetobacter baumannii is increasingly associated with various epidemics, representing a serious concern due to the broad level of antimicrobial resistance and clinical manifestations. During the last decades, A. baumannii has emerged as a major pathogen in vulnerable and critically ill patients. Bacteremia, pneumonia, urinary tract, and skin and soft tissue infections are the most common presentations of A. baumannii, with attributable mortality rates approaching 35%. Carbapenems have been considered the first choice to treat A. baumannii infections. However, due to the widespread prevalence of carbapenem-resistant A. baumannii (CRAB), colistin represents the main therapeutic option, while the role of the new siderophore cephalosporin cefiderocol still needs to be ascertained. Furthermore, high clinical failure rates have been reported for colistin monotherapy when used to treat CRAB infections. Thus, the most effective antibiotic combination remains disputed. In addition to its ability to develop antibiotic resistance, A. baumannii is also known to form biofilm on medical devices, including central venous catheters or endotracheal tubes. Thus, the worrisome spread of biofilm-producing strains in multidrug-resistant populations of A. baumannii poses a significant treatment challenge. This review provides an updated account of antimicrobial resistance patterns and biofilm-mediated tolerance in A. baumannii infections with a special focus on fragile and critically ill patients.
Collapse
Affiliation(s)
- Ilaria Cavallo
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Alessandra Oliva
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
| | - Rebecca Pages
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Francesca Sivori
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Mauro Truglio
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Giorgia Fabrizio
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Martina Pasqua
- Department of Biology and Biotechnology "C. Darwin" Sapienza University of Rome, Rome, Italy
| | - Fulvia Pimpinelli
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Enea Gino Di Domenico
- Department of Biology and Biotechnology "C. Darwin" Sapienza University of Rome, Rome, Italy
| |
Collapse
|
11
|
Calder A, Snyder LAS. Diversity of the type VI secretion systems in the Neisseria spp. Microb Genom 2023; 9. [PMID: 37052605 DOI: 10.1099/mgen.0.000986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Complete Type VI Secretion Systems were identified in the genome sequence data of Neisseria subflava isolates sourced from throat swabs of human volunteers. The previous report was the first to describe two complete Type VI Secretion Systems in these isolates, both of which were distinct in terms of their gene organization and sequence homology. Since publication of the first report, Type VI Secretion System subtypes have been identified in Neisseria spp. The characteristics of each type in N. subflava are further investigated here and in the context of the other Neisseria spp., including identification of the lineages containing the different types and subtypes. Type VI Secretion Systems use VgrG for delivery of toxin effector proteins; several copies of vgrG and associated effector / immunity pairs are present in Neisseria spp. Based on sequence similarity between strains and species, these core Type VI Secretion System genes, vgrG, and effector / immunity genes may diversify via horizontal gene transfer, an instrument for gene acquisition and repair in Neisseria spp.
Collapse
Affiliation(s)
- Alan Calder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
| | - Lori A S Snyder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
| |
Collapse
|
12
|
Hespanhol JT, Karman L, Sanchez-Limache DE, Bayer-Santos E. Intercepting biological messages: Antibacterial molecules targeting nucleic acids during interbacterial conflicts. Genet Mol Biol 2023; 46:e20220266. [PMID: 36880694 PMCID: PMC9990079 DOI: 10.1590/1678-4685-gmb-2022-0266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/25/2022] [Indexed: 03/08/2023] Open
Abstract
Bacteria live in polymicrobial communities and constantly compete for resources. These organisms have evolved an array of antibacterial weapons to inhibit the growth or kill competitors. The arsenal comprises antibiotics, bacteriocins, and contact-dependent effectors that are either secreted in the medium or directly translocated into target cells. During bacterial antagonistic encounters, several cellular components important for life become a weak spot prone to an attack. Nucleic acids and the machinery responsible for their synthesis are well conserved across the tree of life. These molecules are part of the information flow in the central dogma of molecular biology and mediate long- and short-term storage for genetic information. The aim of this review is to summarize the diversity of antibacterial molecules that target nucleic acids during antagonistic interbacterial encounters and discuss their potential to promote the emergence antibiotic resistance.
Collapse
Affiliation(s)
- Julia Takuno Hespanhol
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Lior Karman
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | | | - Ethel Bayer-Santos
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| |
Collapse
|
13
|
Pankov G, Mol Avelar G, Buchanan G, Coulthurst SJ, Hunter WN. The structure of a tautomerase superfamily member linked to the type VI secretion system of Acinetobacter baumannii. Acta Crystallogr F Struct Biol Commun 2023; 79:8-16. [PMID: 36598351 PMCID: PMC9813972 DOI: 10.1107/s2053230x22011414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 11/26/2022] [Indexed: 12/14/2022] Open
Abstract
Bacteria exploit specialized secretion systems to assist in competition for resources, in collaboration and in communication. Here, a protocol for the recombinant production, purification and crystallization of a protein linked to the Acinetobacter baumannii type VI secretion system is provided. A high-resolution structure of this trimeric protein is reported, revealing the characteristic dual β-α-β subunit fold typical of longer subunit members of the tautomerase superfamily. The protein does not appear to be toxic to bacteria or yeast under the conditions tested. The possible biological role of this protein is discussed.
Collapse
Affiliation(s)
- Genady Pankov
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Gabriela Mol Avelar
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Grant Buchanan
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Sarah J. Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - William N. Hunter
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom,Correspondence e-mail:
| |
Collapse
|
14
|
Hespanhol JT, Sanchez-Limache DE, Nicastro GG, Mead L, Llontop EE, Chagas-Santos G, Farah CS, de Souza RF, Galhardo RDS, Lovering AL, Bayer-Santos E. Antibacterial T6SS effectors with a VRR-Nuc domain are structure-specific nucleases. eLife 2022; 11:e82437. [PMID: 36226828 PMCID: PMC9635880 DOI: 10.7554/elife.82437] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/09/2022] [Indexed: 11/21/2022] Open
Abstract
The type VI secretion system (T6SS) secretes antibacterial effectors into target competitors. Salmonella spp. encode five phylogenetically distinct T6SSs. Here, we characterize the function of the SPI-22 T6SS of Salmonella bongori showing that it has antibacterial activity and identify a group of antibacterial T6SS effectors (TseV1-4) containing an N-terminal PAAR-like domain and a C-terminal VRR-Nuc domain encoded next to cognate immunity proteins with a DUF3396 domain (TsiV1-4). TseV2 and TseV3 are toxic when expressed in Escherichia coli and bacterial competition assays confirm that TseV2 and TseV3 are secreted by the SPI-22 T6SS. Phylogenetic analysis reveals that TseV1-4 are evolutionarily related to enzymes involved in DNA repair. TseV3 recognizes specific DNA structures and preferentially cleave splayed arms, generating DNA double-strand breaks and inducing the SOS response in target cells. The crystal structure of the TseV3:TsiV3 complex reveals that the immunity protein likely blocks the effector interaction with the DNA substrate. These results expand our knowledge on the function of Salmonella pathogenicity islands, the evolution of toxins used in biological conflicts, and the endogenous mechanisms regulating the activity of these toxins.
Collapse
Affiliation(s)
- Julia Takuno Hespanhol
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São PauloSão PauloBrazil
| | | | | | - Liam Mead
- Department of Biosciences, University of BirminghamBirminghamUnited Kingdom
| | - Edgar Enrique Llontop
- Departamento de Bioquímica, Instituto de Química, Universidade de São PauloSão PauloBrazil
| | - Gustavo Chagas-Santos
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São PauloSão PauloBrazil
| | - Chuck Shaker Farah
- Departamento de Bioquímica, Instituto de Química, Universidade de São PauloSão PauloBrazil
| | - Robson Francisco de Souza
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São PauloSão PauloBrazil
| | - Rodrigo da Silva Galhardo
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São PauloSão PauloBrazil
| | - Andrew L Lovering
- Department of Biosciences, University of BirminghamBirminghamUnited Kingdom
| | - Ethel Bayer-Santos
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São PauloSão PauloBrazil
| |
Collapse
|
15
|
Golestani F, Malekan M, Rasooli I, Jahangiri A, Ramezanalizadeh F, Chaudhuri S, Farshchi Andisi V, Schryvers AB. Immunogenicity of loop 3 of Omp34 from A. Baumannii in loopless C-lobe of TbpB of N. meningitidis. Int Immunopharmacol 2022; 110:109013. [PMID: 35785727 DOI: 10.1016/j.intimp.2022.109013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/17/2022] [Accepted: 06/27/2022] [Indexed: 12/29/2022]
Abstract
Acinetobacter baumannii is a common causative agent of nosocomial infections, with a mortality rate of 43% in infected patients. Due to the emergence of multidrug-resistant (MDR) strains, vaccine development has become necessary. Since the 34 kDa outer membrane protein Omp34 has been identified as a potential vaccine target, we implemented a hybrid antigen approach to target its extracellular loops. Using bioinformatic and structural analyses, we selected Loop 3 from Omp34 and displayed it on the loopless C-lobe (LCL) of TbpB of Neisseria meningitidis. The hybrid antigen and the LCL were produced and used to immunize mice for passive and active immunization and challenge experiments in which the reactivity of the sera was assessed by ELISAs, the bacterial load in the tissues measured and the survival of immunized mice compared. LCL was ineffective in immunization against A. baumannii thus the resulting immunity was due to the presence of Omp34 loop 3. It resulted in increased survival and a reduced bacterial load in the tissues compared to the control groups. The findings indicate that the immunogenicity of Omp34 loops can induce protection against A. baumannii infection, and it could probably be used as a vaccine candidate to control the pathogenesis of A. baumannii.
Collapse
Affiliation(s)
| | | | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran; Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
| | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems biology and poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | | | - Somshukla Chaudhuri
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Canada
| | - Vahid Farshchi Andisi
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Canada
| | - Anthony B Schryvers
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Canada
| |
Collapse
|
16
|
Li W, Liu X, Tsui W, Xu A, Li D, Zhang X, Li P, Bian X, Zhang J. Identification and Comparative Genomic Analysis of Type VI Secretion Systems and Effectors in Klebsiella pneumoniae. Front Microbiol 2022; 13:853744. [PMID: 35633723 PMCID: PMC9134191 DOI: 10.3389/fmicb.2022.853744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/14/2022] [Indexed: 01/26/2023] Open
Abstract
Klebsiella pneumoniae is a nosocomial opportunistic pathogen that can cause pneumonia, liver abscesses, and infections of the bloodstream. The resistance and pathogenicity of K. pneumoniae pose major challenges to clinical practice. However, the ecology and pathogenic mechanisms of K. pneumoniae have not been fully elucidated. Among these mechanisms, the secretion systems encoded by strains of the bacteria confer adaptive advantages depending on the niche occupied. The type VI secretion system (T6SS) is a multi-protein complex that delivers effector proteins to the extracellular environment or directly to eukaryotic or prokaryotic cells. T6SSs are widely distributed in Gram-negative bacteria and play an important role in bacterial virulence and the interactions between bacteria and other microorganisms or the environment. This study aimed to enhance the understanding of the characteristics of T6SSs in K. pneumoniae through an in-depth comparative genomic analysis of the T6SS in 241 sequenced strains of K. pneumoniae. We identified the T6SS loci, the synteny of the loci in different species, as well as the effectors and core T6SS-related genes in K. pneumoniae. The presence of a T6SS was a common occurrence in K. pneumoniae, and two T6SS clusters are the most prevalent. The variable region downstream of the gene vgrG usually encodes effector proteins. Conserved domain analysis indicated that the identified putative effectors in K. pneumoniae had the functions of lipase, ribonuclease, deoxyribonuclease, and polysaccharide hydrolase. However, some effectors did not contain predicted functional domains, and their specific functions have yet to be elucidated. This in silico study represents a detailed analysis of T6SS-associated genes in K. pneumoniae and provides a foundation for future studies on the mechanism(s) of T6SSs, especially effectors, which may generate new insights into pathogenicity and lead to the identification of proteins with novel antimicrobial properties.
Collapse
Affiliation(s)
- Wanzhen Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiaofen Liu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Waitang Tsui
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai, China
| | - An Xu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Dan Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Xuefei Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Pei Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Xingchen Bian
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jing Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
- Phase I Unit, Huashan Hospital, Fudan University, Shanghai, China
- *Correspondence: Jing Zhang,
| |
Collapse
|
17
|
Garcia Gonzalez J, Hernandez FJ. Nuclease activity: an exploitable biomarker in bacterial infections. Expert Rev Mol Diagn 2022; 22:265-294. [PMID: 35240900 DOI: 10.1080/14737159.2022.2049249] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION In the increasingly challenging field of clinical microbiology, diagnosis is a cornerstone whose accuracy and timing are crucial for the successful management, therapy, and outcome of infectious diseases. Currently employed biomarkers of infectious diseases define the scope and limitations of diagnostic techniques. As such, expanding the biomarker catalog is crucial to address unmet needs and bring about novel diagnostic functionalities and applications. AREAS COVERED This review describes the extracellular nucleases of 15 relevant bacterial pathogens and discusses the potential use of nuclease activity as a diagnostic biomarker. Articles were searched for in PubMed using terms: "nuclease", "bacteria", "nuclease activity" or "biomarker". For overview sections, original and review articles between 2000 and 2019 were searched for using terms: "infections", "diagnosis", "bacterial", "burden", "challenges". Informative articles were selected. EXPERT OPINION Using the catalytic activity of nucleases offers new possibilities compared to established biomarkers. Nucleic acid activatable reporters in combination with different transduction platforms and delivery methods can be used to detect disease-associated nuclease activity patterns in vitro and in vivo for prognostic and diagnostic applications. Even when these patterns are not obvious or of unknown etiology, screening platforms could be used to identify new disease reporters.
Collapse
Affiliation(s)
- Javier Garcia Gonzalez
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.,Wallenberg Centre for Molecular Medicine (WCMM), Linköping, Sweden.,Nucleic Acids Technologies Laboratory (NAT-lab), Linköping University, Linköping, Sweden
| | - Frank J Hernandez
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.,Wallenberg Centre for Molecular Medicine (WCMM), Linköping, Sweden.,Nucleic Acids Technologies Laboratory (NAT-lab), Linköping University, Linköping, Sweden
| |
Collapse
|
18
|
Amaya FA, Blondel CJ, Barros-Infante MF, Rivera D, Moreno-Switt AI, Santiviago CA, Pezoa D. Identification of Type VI Secretion Systems Effector Proteins That Contribute to Interbacterial Competition in Salmonella Dublin. Front Microbiol 2022; 13:811932. [PMID: 35222335 PMCID: PMC8867033 DOI: 10.3389/fmicb.2022.811932] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/04/2022] [Indexed: 12/12/2022] Open
Abstract
The Type VI Secretion System (T6SS) is a multiprotein device that has emerged as an important fitness and virulence factor for many Gram-negative bacteria through the injection of effector proteins into prokaryotic or eukaryotic cells via a contractile mechanism. While some effector proteins specifically target bacterial or eukaryotic cells, others can target both types of cells (trans-kingdom effectors). In Salmonella, five T6SS gene clusters have been identified within pathogenicity islands SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22, which are differentially distributed among serotypes. Salmonella enterica serotype Dublin (S. Dublin) is a cattle-adapted pathogen that harbors both T6SSSPI-6 and T6SSSPI-19. Interestingly, while both systems have been linked to virulence and host colonization in S. Dublin, an antibacterial activity has not been detected for T6SSSPI-6 in this serotype. In addition, there is limited information regarding the repertoire of effector proteins encoded within T6SSSPI-6 and T6SSSPI-19 gene clusters in S. Dublin. In the present study, we demonstrate that T6SSSPI-6 and T6SSSPI-19 of S. Dublin CT_02021853 contribute to interbacterial competition. Bioinformatic and comparative genomic analyses allowed us to identify genes encoding three candidate antibacterial effectors located within SPI-6 and two candidate effectors located within SPI-19. Each antibacterial effector gene is located upstream of a gene encoding a hypothetic immunity protein, thus conforming an effector/immunity (E/I) module. Of note, the genes encoding these effectors and immunity proteins are widely distributed in Salmonella genomes, suggesting a relevant role in interbacterial competition and virulence. Finally, we demonstrate that E/I modules SED_RS01930/SED_RS01935 (encoded in SPI-6), SED_RS06235/SED_RS06230, and SED_RS06335/SED_RS06340 (both encoded in SPI-19) contribute to interbacterial competition in S. Dublin CT_02021853.
Collapse
Affiliation(s)
- Fernando A. Amaya
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos J. Blondel
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | | | - Dácil Rivera
- Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Andrea I. Moreno-Switt
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millennium Initiative on Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
| | - David Pezoa
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
| |
Collapse
|
19
|
Interbacterial Transfer of Carbapenem Resistance and Large Antibiotic Resistance Islands by Natural Transformation in Pathogenic Acinetobacter. mBio 2022; 13:e0263121. [PMID: 35073754 PMCID: PMC8787482 DOI: 10.1128/mbio.02631-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acinetobacter baumannii infection poses a major health threat, with recurrent treatment failure due to antibiotic resistance, notably to carbapenems. While genomic analyses of clinical strains indicate that homologous recombination plays a major role in the acquisition of antibiotic resistance genes, the underlying mechanisms of horizontal gene transfer often remain speculative. Our understanding of the acquisition of antibiotic resistance is hampered by the lack of experimental systems able to reproduce genomic observations. We here report the detection of recombination events occurring spontaneously in mixed bacterial populations and which can result in the acquisition of resistance to carbapenems. We show that natural transformation is the main driver of intrastrain but also interstrain recombination events between A. baumannii clinical isolates and pathogenic species of Acinetobacter. We observed that interbacterial natural transformation in mixed populations is more efficient at promoting the acquisition of large resistance islands (AbaR4 and AbaR1) than when the same bacteria are supplied with large amounts of purified genomic DNA. Importantly, analysis of the genomes of the recombinant progeny revealed large recombination tracts (from 13 to 123 kb) similar to those observed in the genomes of clinical isolates. Moreover, we highlight that transforming DNA availability is a key determinant of the rate of recombinants and results from both spontaneous release and interbacterial predatory behavior. In the light of our results, natural transformation should be considered a leading mechanism of genome recombination and horizontal gene transfer of antibiotic resistance genes in Acinetobacter baumannii.
Collapse
|
20
|
Li H, Tan Y, Zhang D. Genomic discovery and structural dissection of a novel type of polymorphic toxin system in gram-positive bacteria. Comput Struct Biotechnol J 2022; 20:4517-4531. [PMID: 36051883 PMCID: PMC9424270 DOI: 10.1016/j.csbj.2022.08.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/15/2022] [Accepted: 08/15/2022] [Indexed: 11/26/2022] Open
Abstract
Bacteria have developed several molecular conflict systems to facilitate kin recognition and non-kin competition to gain advantages in the acquisition of growth niches and of limited resources. One such example is a large class of so-called polymorphic toxin systems (PTSs), which comprise a variety of the toxin proteins secreted via T2SS, T5SS, T6SS, T7SS and many others. These systems are highly divergent in terms of sequence/structure, domain architecture, toxin-immunity association, and organization of the toxin loci, which makes it difficult to identify and characterize novel systems using traditional experimental and bioinformatic strategies. In recent years, we have been developing and utilizing unique genome-mining strategies and pipelines, based on the organizational principles of both domain architectures and genomic loci of PTSs, for an effective and comprehensive discovery of novel PTSs, dissection of their components, and prediction of their structures and functions. In this study, we present our systematic discovery of a new type of PTS (S8-PTS) in several gram-positive bacteria. We show that the S8-PTS contains three components: a peptidase of the S8 family (subtilases), a polymorphic toxin, and an immunity protein. We delineated the typical organization of these polymorphic toxins, in which a N-terminal signal peptide is followed by a potential receptor binding domain, BetaH, and one of 16 toxin domains. We classified each toxin domain by the distinct superfamily to which it belongs, identifying nine BECR ribonucleases, one Restriction Endonuclease, one HNH nuclease, two novel toxin domains homologous to the VOC enzymes, one toxin domain with the Frataxin-like fold, and several other unique toxin families such as Ntox33 and HicA. Accordingly, we identified 20 immunity families and classified them into different classes of folds. Further, we show that the S8-PTS-associated peptidases are analogous to many other processing peptidases found in T5SS, T7SS, T9SS, and many proprotein-processing peptidases, indicating that they function to release the toxin domains during secretion. The S8-PTSs are mostly found in animal and plant-associated bacteria, including many pathogens. We propose S8-PTSs will facilitate the competition of these bacteria with other microbes or contribute to the pathogen-host interactions.
Collapse
Affiliation(s)
- Huan Li
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA
| | - Yongjun Tan
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA
| | - Dapeng Zhang
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA
- Program of Bioinformatics and Computational Biology, College of Arts & Sciences, Saint Louis University, MO 63103, USA
- Corresponding author at: Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63103, USA.
| |
Collapse
|
21
|
Naghipour Erami A, Rasooli I, Jahangiri A, Darvish Alipour Astaneh S. Anti-Omp34 antibodies protect against Acinetobacter baumannii in a murine sepsis model. Microb Pathog 2021; 161:105291. [PMID: 34798280 DOI: 10.1016/j.micpath.2021.105291] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/10/2021] [Accepted: 11/12/2021] [Indexed: 12/29/2022]
Abstract
Acinetobacter baumannii, an opportunistic extracellular pathogen is one of the major causes of nosocomial infections. Omp34, also known as Omp33-36, is a bacterial porin protein involved in the virulence and fitness of this pathogen by adhesion to the host cell. This antigen nominated as an appropriate candidate for immunization against A. baumannii. In this study, the expression of the recombinant Omp34 (rOmp34) was carried out in E. coli BL21 (DE3). The immunogenicity of the rOmp34 in A. baumannii was studied in a murine sepsis model. Antibody response in mice injected with the recombinant protein was assessed using indirect ELISA. Bactericidal activity of rOmp34-immunized mice sera (1:10 dilution) against A. baumannii ATCC 19606 after 0, 1, 2, 4, and 8 h of incubation at 37 °C was assessed. In addition to survival rate, load of bacteria in liver and spleen of the infected mice were evaluated. A high titer of specific antibody equivalent to optical density of 1.54 ± 0.06 against rOmp34 was elicited in the immunized mice sera. Viability of the A. baumannii incubated 8 h with immunized mice sera was 64%. Homogenized liver and spleen samples of the control mice challenged with A. baumannii were loaded with 8 × 103 and 9 × 103 CFU per gram tissue respectively 48 h post-challenge as against complete clearance of A. baumannii in the immunized group. The protective immunity was achieved by challenging the mice groups with 5 × LD50 of live A. baumannii. Omp34 can be nominated as an immunogen that can bring about protection against Acinetobacter baumannii.
Collapse
Affiliation(s)
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran-Qom Express Way, Iran; Molecular Microbiology Research Center, Shahed University, Tehran-Qom Express Way, Iran.
| | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | | |
Collapse
|
22
|
Massier S, Robin B, Mégroz M, Wright A, Harper M, Hayes B, Cosette P, Broutin I, Boyce JD, Dé E, Hardouin J. Phosphorylation of Extracellular Proteins in Acinetobacter baumannii in Sessile Mode of Growth. Front Microbiol 2021; 12:738780. [PMID: 34659171 PMCID: PMC8517400 DOI: 10.3389/fmicb.2021.738780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/30/2021] [Indexed: 11/21/2022] Open
Abstract
Acinetobacter baumannii is a problematic nosocomial pathogen owing to its increasing resistance to antibiotics and its great ability to survive in the hospital environment, which is linked to its capacity to form biofilms. Structural and functional investigations of post-translational modifications, such as phosphorylations, may lead to identification of candidates for therapeutic targets against this pathogen. Here, we present the first S/T/Y phosphosecretome of two A. baumannii strains, the reference strain ATCC 17978 and the virulent multi-drug resistant strain AB0057, cultured in two modes of growth (planktonic and biofilm) using TiO2 chromatography followed by high resolution mass spectrometry. In ATCC 17978, we detected a total of 137 (97 phosphoproteins) and 52 (33 phosphoproteins) phosphosites in biofilm and planktonic modes of growth, respectively. Similarly, in AB0057, 155 (119 phosphoproteins) and 102 (74 phosphoproteins) phosphosites in biofilm and planktonic modes of growth were identified, respectively. Both strains in the biofilm mode of growth showed a higher number of phosphosites and phosphoproteins compared to planktonic growth. Several phosphorylated sites are localized in key regions of proteins involved in either drug resistance (β-lactamases), adhesion to host tissues (pilins), or protein secretion (Hcp). Site-directed mutagenesis of the Hcp protein, essential for type VI secretion system-mediated interbacterial competition, showed that four of the modified residues are essential for type VI secretion system activity.
Collapse
Affiliation(s)
- Sébastien Massier
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | - Brandon Robin
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Marianne Mégroz
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Amy Wright
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Marina Harper
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Brooke Hayes
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Pascal Cosette
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | | | - John D. Boyce
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Emmanuelle Dé
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Julie Hardouin
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| |
Collapse
|
23
|
Abstract
Many bacterial species employ systems for interference competition with other microorganisms. Some systems are effective without contact (e.g., through secretion of toxins), while other systems (e.g., type VI secretion system [T6SS]) require direct contact between cells. Here, we provide the initial characterization of a novel contact-dependent competition system for Proteus mirabilis. In neonatal mice, a commensal P. mirabilis strain apparently eliminated commensal Escherichia coli. We replicated the phenotype in vitro and showed that P. mirabilis efficiently reduced the viability of several Enterobacteriaceae species but not Gram-positive species or yeast cells. Importantly, P. mirabilis strains isolated from humans also killed E. coli. A reduction of viability occurred from early stationary phase to 24 h of culture and was observed in shaking liquid media as well as on solid media. Killing required contact but was independent of T6SS, which is the only contact-dependent killing system described for P. mirabilis. Expression of the killing system was regulated by osmolarity and components secreted into the supernatant. Stationary-phase P. mirabilis culture supernatant itself did not kill but was sufficient to induce killing in an exponentially growing coculture. In contrast, killing was largely prevented in media with low osmolarity. In summary, we provide the initial characterization of a potentially novel interbacterial competition system used by P. mirabilis. IMPORTANCE The study of bacterial competition systems has received significant attention in recent years. These systems are important in a multitude of polymicrobial environments and collectively shape the composition of complex ecosystems like the mammalian gut. They are also being explored as narrow-spectrum alternatives to specifically eliminate problematic pathogenic species. However, only a small fraction of the estimated number of interbacterial competition systems has been identified. We discovered a competition system that is novel for Proteus mirabilis. Inspired by an observation in infant mice, we confirmed in vitro that P. mirabilis was able to efficiently kill several Enterobacteriaceae species. This killing system might represent a new function of a known competition system or even a novel system, as the observed characteristics do not fit with described contact-dependent competition systems. Further characterization of this system might help understand how P. mirabilis competes with other Enterobacteriaceae in various niches.
Collapse
|
24
|
Cameranesi MM, Kurth D, Repizo GD. Acinetobacter defence mechanisms against biological aggressors and their use as alternative therapeutic applications. Crit Rev Microbiol 2021; 48:21-41. [PMID: 34289313 DOI: 10.1080/1040841x.2021.1939266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Several Acinetobacter strains are important nosocomial pathogens, with Acinetobacter baumannii being the species of greatest worldwide concern due to its multi-drug resistance and the recent appearance of hyper-virulent strains in the clinical setting. Colonisation of this environment is associated with a multitude of bacterial factors, and the molecular features that promote environmental persistence in abiotic surfaces, including intrinsic desiccation resistance, biofilm formation and motility, have been previously addressed. On the contrary, mechanisms enabling Acinetobacter spp. survival when faced against other biological competitors are starting to be characterised. Among them, secretion systems (SS) of different types, such as the T5bSS (Contact-dependent inhibition systems) and the T6SS, confer adaptive advantages against bacterial aggressors. Regarding mechanisms of defence against bacteriophages, such as toxin-antitoxin, restriction-modification, Crispr-Cas and CBASS, among others, have been identified but remain poorly characterised. In view of this, we aimed to summarise the present knowledge on defence mechanisms that enable niche establishment in members of the Acinetobacter genus. Different proposals are also described for the use of some components of these systems as molecular tools to treat Acinetobacter infections.
Collapse
Affiliation(s)
- María Marcela Cameranesi
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Daniel Kurth
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI, CONICET), San Miguel de Tucumán, Argentina
| | - Guillermo Daniel Repizo
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| |
Collapse
|
25
|
Yadav SK, Magotra A, Ghosh S, Krishnan A, Pradhan A, Kumar R, Das J, Sharma M, Jha G. Immunity proteins of dual nuclease T6SS effectors function as transcriptional repressors. EMBO Rep 2021; 22:e51857. [PMID: 33786997 PMCID: PMC8183406 DOI: 10.15252/embr.202051857] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/26/2021] [Accepted: 03/08/2021] [Indexed: 12/31/2022] Open
Abstract
Bacteria utilize type VI secretion system (T6SS) to deliver antibacterial toxins to target co-habiting bacteria. Here, we report that Burkholderia gladioli strain NGJ1 deploys certain T6SS effectors (TseTBg), having both DNase and RNase activities to kill target bacteria. RNase activity is prominent on NGJ1 as well as other bacterial RNA while DNase activity is pertinent to only other bacteria. The associated immunity (TsiTBg) proteins harbor non-canonical helix-turn-helix motifs and demonstrate transcriptional repression activity, similar to the antitoxins of type II toxin-antitoxin (TA) systems. Genome analysis reveals that homologs of TseTBg are either encoded as TA or T6SS effectors in diverse bacteria. Our results indicate that a new ORF (encoding a hypothetical protein) has evolved as a result of operonic fusion of TA type TseTBg homolog with certain T6SS-related genes by the action of IS3 transposable elements. This has potentially led to the conversion of a TA into T6SS effector in Burkholderia. Our study exemplifies that bacteria can recruit toxins of TA systems as T6SS weapons to diversify its arsenal to dominate during inter-bacterial competitions.
Collapse
Affiliation(s)
- Sunil Kumar Yadav
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Ankita Magotra
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Srayan Ghosh
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Aiswarya Krishnan
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Amrita Pradhan
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Rahul Kumar
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Joyati Das
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Mamta Sharma
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Gopaljee Jha
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| |
Collapse
|
26
|
Pazoki M, Darvish Alipour Astaneh S, Ramezanalizadeh F, Jahangiri A, Rasooli I. Immunoprotectivity of Valine-glycine repeat protein G, a potent mediator of pathogenicity, against Acinetobacter baumannii. Mol Immunol 2021; 135:276-284. [PMID: 33940514 DOI: 10.1016/j.molimm.2021.04.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 03/19/2021] [Accepted: 04/26/2021] [Indexed: 10/21/2022]
Abstract
Type VI Secretion System (T6SS) contributes to both virulence and antimicrobial resistance in Acinetobacter baumannii. Valine-glycine repeat protein G (VgrG) is the core component of T6SS that exists in many bacterial pathogens that have emerged as a potent mediator of pathogenicity in A. baumannii. Two conserved sequences of vgrG 1263-2295 and vgrG1263-1608 were identified antigenic in various strains of Acinetobacter baumannii. The vgrg1263-1608 sequence was implanted in the Loopless C lobe (LCL) from N. meningitidis for surface display and exposure to functional epitopes. The VgrG and LCL-VgrG were expressed and purified. Groups of BALB/c mice were immunized with these proteins and challenged with A. baumannii. Specific IgG titers, whole-cell ELISA, animal survival rates in active and passive immunizations, the bacterial burden in mice tissues, and cytotoxicity of the proteins were determined. The specific IgG suppressed bacterial burdens in the organs, and increased survival rates were noted in the immunized mice. LCL-VgrG immunization provided better protection against A. baumannii infection than the VgrG immunization. The conserved region of VgrG is probably a safe immunogen to effective vaccine development or an antiserum to control A. baumannii infections.
Collapse
Affiliation(s)
| | - Shakiba Darvish Alipour Astaneh
- Department of Biotechnology, Semnan University, Central Administration of Semnan University, Campus 1, P.O. Box 35131 -19111, I. R. of Iran Semnan, Semnan, Iran
| | | | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran; Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
| |
Collapse
|
27
|
Liu Y, Zhang Z, Wang F, Li DD, Li YZ. Identification of type VI secretion system toxic effectors using adaptors as markers. Comput Struct Biotechnol J 2020; 18:3723-3733. [PMID: 33304467 PMCID: PMC7714669 DOI: 10.1016/j.csbj.2020.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/31/2020] [Accepted: 11/02/2020] [Indexed: 12/18/2022] Open
Abstract
Each class of adaptors can be used as an effective marker to identify T6SS effectors. The PRK06147 homolog may be a novel adaptor. 1356 putative toxic effectors related to adaptors from 92 families were identified.
Toxic effectors secreted by the type VI secretion system (T6SS) facilitate interbacterial warfare, as well as pathogenesis toward humans, animals and plants. However, systematically predicting T6SS effectors remains challenging due to their sequence and functional diversity. In this study, we systematically identified putative T6SS toxic effectors in prokaryotic genomes on the basis of the observation that genes encoding adaptor proteins and genes encoding cognate effector proteins are generally adjacent in the genome. Adaptor proteins are mediators that help to load their cognate effectors onto the T6SS spike complex. The contextual genes of the known adaptor proteins (DUF1795, DUF2169 or DUF4123) all exhibited a high proportion of encoding T6SS spike complex protein (VgrG or PAAR) and effector proteins. On the basis of the genomic context, we found that PRK06147 might be a novel adaptor protein. These four adaptors are widely distributed among the bacterial genomes. From neighbors of 5297 adaptor genes, we identified 1356 putative effector genes from 92 different families, and two-thirds were currently annotated as hypothetical proteins or as having unknown functions. Our results indicate that each class of adaptors can be used as an effective marker to identify T6SS toxic effectors, moreover, this approach can promote the discovery of new effectors.
Collapse
Affiliation(s)
- Ya Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Zheng Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China.,Suzhou Research Institute, Shandong University, Suzhou 215123, China
| | - Feng Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Dan-Dan Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Yue-Zhong Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| |
Collapse
|
28
|
Nang SC, Han ML, Yu HH, Wang J, Torres VVL, Dai C, Velkov T, Harper M, Li J. Polymyxin resistance in Klebsiella pneumoniae: multifaceted mechanisms utilized in the presence and absence of the plasmid-encoded phosphoethanolamine transferase gene mcr-1. J Antimicrob Chemother 2020; 74:3190-3198. [PMID: 31365098 DOI: 10.1093/jac/dkz314] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 06/13/2019] [Accepted: 06/21/2019] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVES Until plasmid-mediated mcr-1 was discovered, it was believed that polymyxin resistance in Gram-negative bacteria was mainly mediated by the chromosomally-encoded EptA and ArnT, which modify lipid A with phosphoethanolamine (pEtN) and 4-amino-4-deoxy-l-arabinose (l-Ara4N), respectively. This study aimed to construct a markerless mcr-1 deletion mutant in Klebsiella pneumoniae, validate a reliable reference gene for reverse transcription quantitative PCR (RT-qPCR) and investigate the interactions among mcr-1, arnT and eptA, in response to polymyxin treatments using pharmacokinetics/pharmacodynamics (PK/PD). METHODS An isogenic markerless mcr-1 deletion mutant (II-503Δmcr-1) was generated from a clinical K. pneumoniae II-503 isolate. The efficacy of different polymyxin B dosage regimens was examined using an in vitro one-compartment PK/PD model and polymyxin resistance was assessed using population analysis profiles. The expression of mcr-1, eptA and arnT was examined using RT-qPCR with a reference gene pepQ, and lipid A was profiled using LC-MS. In vivo polymyxin B efficacy was investigated in a mouse thigh infection model. RESULTS In K. pneumoniae II-503, mcr-1 was constitutively expressed, irrespective of polymyxin exposure. Against II-503Δmcr-1, an initial bactericidal effect was observed within 4 h with polymyxin B at average steady-state concentrations of 1 and 3 mg/L, mimicking patient PK. However, substantial regrowth and concomitantly increased expression of eptA and arnT were detected. Predominant l-Ara4N-modified lipid A species were detected in II-503Δmcr-1 following polymyxin B treatment. CONCLUSIONS This is the first study demonstrating a unique markerless deletion of mcr-1 in a clinical polymyxin-resistant K. pneumoniae. The current polymyxin B dosage regimens are suboptimal against K. pneumoniae, regardless of mcr, and can lead to the emergence of resistance.
Collapse
Affiliation(s)
- Sue C Nang
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Mei-Ling Han
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Heidi H Yu
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Jiping Wang
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Von Vergel L Torres
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Chongshan Dai
- College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Tony Velkov
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Marina Harper
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Jian Li
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| |
Collapse
|
29
|
Barretto LAF, Fowler CC. Identification of A Putative T6SS Immunity Islet in Salmonella Typhi. Pathogens 2020; 9:pathogens9070559. [PMID: 32664482 PMCID: PMC7400221 DOI: 10.3390/pathogens9070559] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 12/19/2022] Open
Abstract
Typhoid fever is a major global health problem and is the result of systemic infections caused by the human-adapted bacterial pathogen Salmonella enterica serovar Typhi (S. Typhi). The pathology underlying S. Typhi infections significantly differ from infections caused by broad host range serovars of the same species, which are a common cause of gastroenteritis. Accordingly, identifying S. Typhi genetic factors that impart functionality absent from broad host range serovars offers insights into its unique biology. Here, we used an in-silico approach to explore the function of an uncharacterized 14-gene S. Typhi genomic islet. Our results indicated that this islet was specific to the S. enterica species, where it was encoded by the Typhi and Paratyphi A serovars, but was generally absent from non-typhoidal serovars. Evidence was gathered using comparative genomics and sequence analysis tools, and indicated that this islet was comprised of Type VI secretion system (T6SS) and contact-dependent growth inhibition (CDI) genes, the majority of which appeared to encode orphan immunity proteins that protected against the activities of effectors and toxins absent from the S. Typhi genome. We herein propose that this islet represents an immune system that protects S. Typhi against competing bacteria within the human gut.
Collapse
|
30
|
Ma S, Dong Y, Wang N, Liu J, Lu C, Liu Y. Identification of a new effector-immunity pair of Aeromonas hydrophila type VI secretion system. Vet Res 2020; 51:71. [PMID: 32448355 PMCID: PMC7245790 DOI: 10.1186/s13567-020-00794-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 04/26/2020] [Indexed: 12/23/2022] Open
Abstract
The type VI secretion system (T6SS) is a multiprotein weapon that kills eukaryotic predators or prokaryotic competitors by delivering toxic effectors. Despite the importance of T6SS in bacterial environmental adaptation, it is still challenging to systematically identify T6SS effectors because of their high diversity and lack of conserved domains. In this report, we discovered a putative effector gene, U876-17730, in the whole genome of Aeromonas hydrophila NJ-35 based on the reported conservative domain DUF4123 (domain of unknown function), with two cognate immunity proteins encoded downstream. Phylogenetic tree analysis of amino acids indicates that AH17730 belongs to the Tle1 (type VI lipase effector) family, and therefore was named Tle1AH. The deletion of tle1AH resulted in significantly decreased biofilm formation, antibacterial competition ability and virulence in zebrafish (Danio rerio) when compared to the wild-type strain. Only when the two immunity proteins coexist can bacteria protect themselves from the toxicity of Tle1AH. Further study shows that Tle1AH is a kind of phospholipase that possesses a conserved lipase motif, Gly-X-Ser-X-Gly (X is for any amino acid). Tle1AH is secreted by T6SS, and this secretion requires its interaction with an associated VgrG (valine-glycine repeat protein G). In conclusion, we identified a T6SS effector-immunity pair and verified its function, which lays the foundation for future research on the role of T6SS in the pathogenic mechanism of A. hydrophila.
Collapse
Affiliation(s)
- Shuiyan Ma
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuhao Dong
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Nannan Wang
- College of Animal Science and Technology, Jinling Institute of Technology, Nanjing, 211169, China
| | - Jin Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| |
Collapse
|
31
|
Álvarez VE, Quiroga MP, Galán AV, Vilacoba E, Quiroga C, Ramírez MS, Centrón D. Crucial Role of the Accessory Genome in the Evolutionary Trajectory of Acinetobacter baumannii Global Clone 1. Front Microbiol 2020; 11:342. [PMID: 32256462 PMCID: PMC7093585 DOI: 10.3389/fmicb.2020.00342] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 02/17/2020] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii is one of the most important nosocomial pathogens able to rapidly develop extensive drug resistance. Here, we study the role of accessory genome in the success of the globally disseminated clone 1 (GC1) with functional and genomic approaches. Comparative genomics was performed with available GC1 genomes (n = 106) against other A. baumannii high-risk and sporadic clones. Genetic traits related to accessory genome were found common and conserved along time as two novel regions of genome plasticity, and a CRISPR-Cas system acquired before clonal diversification located at the same loci as “sedentary” modules. Although identified within hotspot for recombination, other block of accessory genome was also “sedentary” in lineage 1 of GC1 with signs of microevolution as the AbaR0-type genomic island (GI) identified in A144 and in A155 strains which were maintained one month in independent experiments without antimicrobial pressure. The prophage YMC/09/02/B1251_ABA_BP was found to be “mobile” since, although it was shared by all GC1 genomes, it showed high intrinsic microevolution as well as mobility to different insertion sites. Interestingly, a wide variety of Insertion Sequences (IS), probably acquired by the flow of plasmids related to Rep_3 superfamily was found. These IS showed dissimilar genomic location amongst GC1 genomes presumably associated with promptly niche adaptation. On the other hand, a type VI secretion system and three efflux pumps were subjected to deep processes of genomic loss in A. baumannii but not in GC1. As a whole, these findings suggest that preservation of some genetic modules of accessory genome harbored by strains from different continents in combination with great plasticity of IS and varied flow of plasmids, may be central features of the genomic structure of GC1. Competition of A144 and A155 versus A118 (ST 404/ND) without antimicrobial pressure suggested a higher ability of GC1 to grow over a clone with sporadic behavior which explains, from an ecological perspective, the global achievement of this successful pandemic clone in the hospital habitat. Together, these data suggest an essential role of still unknown properties of “mobile” and “sedentary” accessory genome that is preserved over time under different antibiotic or stress conditions.
Collapse
Affiliation(s)
- Verónica Elizabeth Álvarez
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - María Paula Quiroga
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Angélica Viviana Galán
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Elisabet Vilacoba
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Cecilia Quiroga
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - María Soledad Ramírez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, United States
| | - Daniela Centrón
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| |
Collapse
|
32
|
Santos MNM, Cho ST, Wu CF, Chang CJ, Kuo CH, Lai EM. Redundancy and Specificity of Type VI Secretion vgrG Loci in Antibacterial Activity of Agrobacterium tumefaciens 1D1609 Strain. Front Microbiol 2020; 10:3004. [PMID: 31993035 PMCID: PMC6971182 DOI: 10.3389/fmicb.2019.03004] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/12/2019] [Indexed: 12/14/2022] Open
Abstract
Type VI secretion system (T6SS) is a contractile nanoweapon employed by many Proteobacteria to deliver effectors to kill or inhibit their competitors. One T6SS gene, vgrG, encodes a spike protein for effector translocation and is often present as multiple copies in bacterial genomes. Our phylogenomic analyses sampled 48 genomes across diverse Proteobacteria lineages and found ∼70% of them encode multiple VgrGs, yet only four genomes have nearly identical paralogs. Among these four, Agrobacterium tumefaciens 1D1609 has the highest vgrG redundancy. Compared to A. tumefaciens model strain C58 which harbors two vgrG genes, 1D1609 encodes four vgrG genes (i.e., vgrGa-d) with each adjacent to different putative effector genes. Thus, 1D1609 was selected to investigate the functional redundancy and specificity of multiple vgrG genes and their associated effectors. Secretion assay of single and multiple vgrG deletion mutants demonstrated that these four vgrGs are functionally redundant in mediating T6SS secretion. By analyzing various vgrG mutants, we found that all except for the divergent vgrGb could contribute to 1D1609’s antibacterial activity. Further characterizations of putative effector-immunity gene pairs revealed that vgrGa-associated gene 2 (v2a) encodes an AHH family nuclease and serves as the major antibacterial toxin. Interestingly, C58’s VgrG2 shares 99% amino acid sequence identity with 1D1609’s VgrGa, VgrGc and VgrGd. This high sequence similarity allows 1D1609 to use an exogenous VgrG delivered from C58 to kill another competing bacterium. Taken together, Agrobacterium can use highly similar VgrGs, either produced endogenously or injected from its close relatives, for T6SS-mediated interbacterial competition.
Collapse
Affiliation(s)
- Mary Nia M Santos
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.,Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, Taiwan.,Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Shu-Ting Cho
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Chih-Feng Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Chun-Ju Chang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.,Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, Taiwan.,Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.,Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, Taiwan.,Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| |
Collapse
|
33
|
Lopez J, Ly PM, Feldman MF. The Tip of the VgrG Spike Is Essential to Functional Type VI Secretion System Assembly in Acinetobacter baumannii. mBio 2020; 11:e02761-19. [PMID: 31937641 PMCID: PMC6960284 DOI: 10.1128/mbio.02761-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/25/2019] [Indexed: 12/11/2022] Open
Abstract
The type VI secretion system (T6SS) is a critical weapon in bacterial warfare between Gram-negative bacteria. Although invaluable for niche establishment, this machine represents an energetic burden to its host bacterium. Acinetobacter baumannii is an opportunistic pathogen that poses a serious threat to public health due to its high rates of multidrug resistance. In some A. baumannii strains, the T6SS is transcriptionally downregulated by large multidrug resistance plasmids. Other strains, such as the clinical isolate AbCAN2, express T6SS-related genes but lack T6SS activity under laboratory conditions, despite not harboring these plasmids. This suggests that alternative mechanisms exist to repress the T6SS. Here, we used a transposon mutagenesis approach in AbCAN2 to identify novel T6SS repressors. Our screen revealed that the T6SS of this strain is inhibited by a homolog of VgrG, an essential structural component of all T6SSs reported to date. We named this protein inhibitory VgrG (VgrGi). Biochemical and in silico analyses demonstrated that the unprecedented inhibitory capability of VgrGi is due to a single amino acid mutation in a widely conserved C-terminal domain of unknown function, DUF2345. We also show that unlike in other bacteria, the C terminus of VgrG is essential for functional T6SS assembly in A. baumannii Our study provides insight into the architectural requirements underlying functional assembly of the T6SS of A. baumannii We propose that T6SS-inactivating point mutations are beneficial to the host bacterium, since they eliminate the energy cost associated with maintaining a functional T6SS, which appears to be unnecessary for A. baumannii virulence.IMPORTANCE Despite the clinical relevance of A. baumannii, little is known about its fundamental biology. Here, we show that a single amino acid mutation in VgrG, a critical T6SS structural protein, abrogates T6SS function. Given that this mutation was found in a clinical isolate, we propose that the T6SS of A. baumannii is probably not involved in virulence; this idea is supported by multiple genomic analyses showing that the majority of clinical A. baumannii strains lack proteins essential to the T6SS. We also show that, unlike in other species, the C terminus of VgrG is a unique architectural requirement for functional T6SS assembly in A. baumannii, suggesting that over evolutionary time, bacteria have developed changes to their T6SS architecture, leading to specialized systems.
Collapse
Affiliation(s)
- Juvenal Lopez
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Pek Man Ly
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| |
Collapse
|
34
|
Liaw J, Hong G, Davies C, Elmi A, Sima F, Stratakos A, Stef L, Pet I, Hachani A, Corcionivoschi N, Wren BW, Gundogdu O, Dorrell N. The Campylobacter jejuni Type VI Secretion System Enhances the Oxidative Stress Response and Host Colonization. Front Microbiol 2019; 10:2864. [PMID: 31921044 PMCID: PMC6927950 DOI: 10.3389/fmicb.2019.02864] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 11/26/2019] [Indexed: 12/15/2022] Open
Abstract
The role of the Type VI secretion system (T6SS) in Campylobacter jejuni is poorly understood despite an increasing prevalence of the T6SS in recent C. jejuni isolates in humans and chickens. The T6SS is a contractile secretion machinery capable of delivering effectors that can play a role in host colonization and niche establishment. During host colonization, C. jejuni is exposed to oxidative stress in the host gastrointestinal tract, and in other bacteria the T6SS has been linked with the oxidative stress response. In this study, comparisons of whole genome sequences of a novel human isolate 488 with previously sequenced strains revealed a single highly conserved T6SS cluster shared between strains isolated from humans and chickens. The presence of a functional T6SS in the 488 wild-type strain is indicated by expression of T6SS genes and secretion of the effector TssD. Increased expression of oxidative stress response genes katA, sodB, and ahpC, and increased oxidative stress resistance in 488 wild-type strain suggest T6SS is associated with oxidative stress response. The role of the T6SS in interactions with host cells is explored using in vitro and in vivo models, and the presence of the T6SS is shown to increase C. jejuni cytotoxicity in the Galleria mellonella infection model. In biologically relevant models, the T6SS enhances C. jejuni interactions with and invasion of chicken primary intestinal cells and enhances the ability of C. jejuni to colonize chickens. This study demonstrates that the C. jejuni T6SS provides defense against oxidative stress and enhances host colonization, and highlights the importance of the T6SS during in vivo survival of T6SS-positive C. jejuni strains.
Collapse
Affiliation(s)
- Janie Liaw
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Geunhye Hong
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Cadi Davies
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Abdi Elmi
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Filip Sima
- Bacteriology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom
| | - Alexandros Stratakos
- Bacteriology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom
| | - Lavinia Stef
- Bioengineering of Animal Science Resources, Banat University of Agricultural Sciences and Veterinary Medicine - King Michael the I of Romania, Timisoara, Romania
| | - Ioan Pet
- Bioengineering of Animal Science Resources, Banat University of Agricultural Sciences and Veterinary Medicine - King Michael the I of Romania, Timisoara, Romania
| | - Abderrahman Hachani
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.,The Peter Doherty Institute for Infection and Immunity, Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, Australia
| | - Nicolae Corcionivoschi
- Bacteriology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom.,Bioengineering of Animal Science Resources, Banat University of Agricultural Sciences and Veterinary Medicine - King Michael the I of Romania, Timisoara, Romania
| | - Brendan W Wren
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Ozan Gundogdu
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Nick Dorrell
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| |
Collapse
|
35
|
Jana B, Salomon D. Type VI secretion system: a modular toolkit for bacterial dominance. Future Microbiol 2019; 14:1451-1463. [DOI: 10.2217/fmb-2019-0194] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria use toxin delivery systems, such as the type VI secretion system (T6SS), to antagonize competitors. The T6SS transports toxins, called effectors, directly into recipient cells. In the absence of cognate immunity proteins that protect against kin-intoxication, these effectors target conserved and essential cell components resulting in growth arrest or cell death. Here, we focus on antibacterial T6SS effectors and explore their different activities, modes of delivery, and the domains and proteins that are associated with them to provide a modular and dynamic toxin arsenal. We conclude that these natural machines present a lucrative pool and platform for future antibacterial treatments.
Collapse
Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Dor Salomon
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| |
Collapse
|
36
|
Repizo GD, Espariz M, Seravalle JL, Salcedo SP. Bioinformatic Analysis of the Type VI Secretion System and Its Potential Toxins in the Acinetobacter Genus. Front Microbiol 2019; 10:2519. [PMID: 31736933 PMCID: PMC6838775 DOI: 10.3389/fmicb.2019.02519] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
Several Acinetobacter strains are important nosocomial pathogens, with Acinetobacter baumannii as the species of greatest concern worldwide due to its multi-drug resistance and recent appearance of hyper-virulent strains in the clinical setting. Acinetobacter colonization of the environment and the host is associated with a multitude of factors which remain poorly characterized. Among them, the secretion systems (SS) encoded by Acinetobacter species confer adaptive advantages depending on the niche occupied. Different SS have been characterized in this group of microorganisms, including T6SS used by several Acinetobacter species to outcompete other bacteria and in some A. baumannii strains for Galleria mellonella colonization. Therefore, to better understand the distribution of the T6SS in this genus we carried out an in-depth comparative genomic analysis of the T6SS in 191 sequenced strains. To this end, we analyzed the gene content, sequence similarity, synteny and operon structure of each T6SS loci. The presence of a single conserved T6SS-main cluster (T6SS-1), with two different genetic organizations, was detected in the genomes of several ecologically diverse species. Furthermore, a second main cluster (T6SS-2) was detected in a subgroup of 3 species of environmental origin. Detailed analysis also showed an impressive genetic versatility in T6SS-associated islands, carrying VgrG, PAAR and putative toxin-encoding genes. This in silico study represents the first detailed intra-species comparative analysis of T6SS-associated genes in the Acinetobacter genus, that should contribute to the future experimental characterization of T6SS proteins and effectors.
Collapse
Affiliation(s)
- Guillermo D Repizo
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Martín Espariz
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Joana L Seravalle
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Suzana P Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry, CNRS UMR 5086, University of Lyon, Lyon, France
| |
Collapse
|
37
|
Lewis JM, Deveson Lucas D, Harper M, Boyce JD. Systematic Identification and Analysis of Acinetobacter baumannii Type VI Secretion System Effector and Immunity Components. Front Microbiol 2019; 10:2440. [PMID: 31736890 PMCID: PMC6833914 DOI: 10.3389/fmicb.2019.02440] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 10/10/2019] [Indexed: 12/17/2022] Open
Abstract
Many Gram-negative bacteria use a type VI secretion system (T6SS) for microbial warfare and/or host manipulation. Acinetobacter baumannii is an important nosocomial pathogen and many A. baumannii strains utilize a T6SS to deliver toxic effector proteins to surrounding bacterial cells. These toxic effectors are usually delivered together with VgrG proteins, which form part of the T6SS tip complex. All previously identified A. baumannii T6SS effectors are encoded within a three- or four-gene locus that also encodes a cognate VgrG and immunity protein, and sometimes a chaperone. In order to characterize the diversity and distribution of T6SS effectors and immunity proteins in this species, we first identified all vgrG genes in 97 A. baumannii strains via the presence of the highly conserved VgrG domain. Most strains encoded between two and four different VgrG proteins. We then analyzed the regions downstream of the identified vgrG genes and identified more than 240 putative effectors. The presence of conserved domains in these effectors suggested a range of functions, including peptidoglycan hydrolases, lipases, nucleases, and nucleic acid deaminases. However, 10 of the effector groups had no functionally characterized domains. Phylogenetic analysis of these putative effectors revealed that they clustered into 32 distinct groups that appear to have been acquired from a diverse set of ancestors. Corresponding immunity proteins were identified for all but two of the effector groups. Effectors from eight of the 32 groups contained N-terminal rearrangement hotspot (RHS) domains. The C-terminal regions of these RHS proteins, which are predicted to confer the toxic effector function, were very diverse, but the N-terminal RHS domains clustered into just two groups. While the majority of A. baumannii strains contained an RHS type effector, no strains encoded two RHS effectors with similar N-terminal sequences, suggesting that the presence of similar N-terminal RHS domains leads to competitive exclusion. Together, these analyses define the extreme diversity of T6SS effectors within A. baumannii and, as many have unknown functions, future detailed characterization of these effectors may lead to the identification of proteins with novel antibacterial properties.
Collapse
Affiliation(s)
- Jessica M Lewis
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Deanna Deveson Lucas
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Marina Harper
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - John D Boyce
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| |
Collapse
|
38
|
Geisinger E, Huo W, Hernandez-Bird J, Isberg RR. Acinetobacter baumannii: Envelope Determinants That Control Drug Resistance, Virulence, and Surface Variability. Annu Rev Microbiol 2019; 73:481-506. [DOI: 10.1146/annurev-micro-020518-115714] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acinetobacter baumannii has emerged as an important nosocomial pathogen, particularly for patients in intensive care units and with invasive indwelling devices. The most recent clinical isolates are resistant to several classes of clinically important antibiotics, greatly restricting the ability to effectively treat critically ill patients. The bacterial envelope is an important driver of A. baumannii disease, both at the level of battling against antibiotic therapy and at the level of protecting from host innate immune function. This review provides a comprehensive overview of key features of the envelope that interface with both the host and antimicrobial therapies. Carbohydrate structures that contribute to protecting from the host are detailed, and mutations that alter these structures, resulting in increased antimicrobial resistance, are explored. In addition, protein complexes involved in both intermicrobial and host-microbe interactions are described. Finally we discuss regulatory mechanisms that control the nature of the cell envelope and its impact on host innate immune function.
Collapse
Affiliation(s)
- Edward Geisinger
- Department of Biology, Northeastern University, Boston, Massachusetts 02115, USA
| | - Wenwen Huo
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
| | - Juan Hernandez-Bird
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
| | - Ralph R. Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
| |
Collapse
|
39
|
Morris FC, Dexter C, Kostoulias X, Uddin MI, Peleg AY. The Mechanisms of Disease Caused by Acinetobacter baumannii. Front Microbiol 2019; 10:1601. [PMID: 31379771 PMCID: PMC6650576 DOI: 10.3389/fmicb.2019.01601] [Citation(s) in RCA: 155] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 06/26/2019] [Indexed: 01/29/2023] Open
Abstract
Acinetobacter baumannii is a Gram negative opportunistic pathogen that has demonstrated a significant insurgence in the prevalence of infections over recent decades. With only a limited number of “traditional” virulence factors, the mechanisms underlying the success of this pathogen remain of great interest. Major advances have been made in the tools, reagents, and models to study A. baumannii pathogenesis, and this has resulted in a substantial increase in knowledge. This article provides a comprehensive review of the bacterial virulence factors, the host immune responses, and animal models applicable for the study of this important human pathogen. Collating the most recent evidence characterizing bacterial virulence factors, their cellular targets and genetic regulation, we have encompassed numerous aspects important to the success of this pathogen, including membrane proteins and cell surface adaptations promoting immune evasion, mechanisms for nutrient acquisition and community interactions. The role of innate and adaptive immune responses is reviewed and areas of paucity in our understanding are highlighted. Finally, with the vast expansion of available animal models over recent years, we have evaluated those suitable for use in the study of Acinetobacter disease, discussing their advantages and limitations.
Collapse
Affiliation(s)
- Faye C Morris
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Carina Dexter
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Xenia Kostoulias
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Muhammad Ikhtear Uddin
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Anton Y Peleg
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, VIC, Australia
| |
Collapse
|
40
|
The type VI secretion system protein AsaA in Acinetobacter baumannii is a periplasmic protein physically interacting with TssM and required for T6SS assembly. Sci Rep 2019; 9:9438. [PMID: 31263148 PMCID: PMC6602968 DOI: 10.1038/s41598-019-45875-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/13/2019] [Indexed: 11/11/2022] Open
Abstract
Type VI secretion system (T6SS) is described as a macromolecular secretion machine that is utilized for bacterial competition. The gene clusters encoding T6SS are composed of core tss genes and tag genes. However, the clusters differ greatly in different pathogens due to the great changes accumulated during the long-term evolution. In this work, we identified a novel hypothetical periplasmic protein designated as AsaA which is encoded by the first gene of the T6SS cluster in the genus Acinetobacter. By constructing asaA mutant, we delineated its relative contributions to bacterial competition and secretion of T6SS effector Hcp. Subsequently, we studied the localization of AsaA and potential proteins that may have interactions with AsaA. Our results showed that AsaA in Acinetobacter baumannii (A. baumannii) localized in the bacterial periplasmic space. Results based on bacterial two-hybrid system and protein pull-down assays indicated that it was most likely to affect the assembly or stability of T6SS by interacting with the T6SS core protein TssM. Collectively, our findings of AsaA is most likely a key step in understanding of the T6SS functions in A. baumannii.
Collapse
|
41
|
Coulthurst S. The Type VI secretion system: a versatile bacterial weapon. Microbiology (Reading) 2019; 165:503-515. [DOI: 10.1099/mic.0.000789] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Sarah Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| |
Collapse
|
42
|
Abstract
The Type VI secretion system (T6SS) is a protein nanomachine that is widespread in Gram-negative bacteria and is used to translocate effector proteins directly into neighbouring cells. It represents a versatile bacterial weapon that can deliver effectors into distinct classes of target cells, playing key roles in inter-bacterial competition and bacterial interactions with eukaryotic cells. This versatility is underpinned by the ability of the T6SS to deliver a vast array of effector proteins, with many distinct activities and modes of interaction with the secretion machinery. Recent work has highlighted the importance and diversity of interactions mediated by T6SSs within polymicrobial communities, and offers new molecular insights into effector delivery and action in target cells.
Collapse
Affiliation(s)
- Sarah Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| |
Collapse
|