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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.
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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
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2
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Cianciotto NP. The type II secretion system as an underappreciated and understudied mediator of interbacterial antagonism. Infect Immun 2024:e0020724. [PMID: 38980047 DOI: 10.1128/iai.00207-24] [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: 07/10/2024] Open
Abstract
Interbacterial antagonism involves all major phyla, occurs across the full range of ecological niches, and has great significance for the environment, clinical arena, and agricultural and industrial sectors. Though the earliest insight into interbacterial antagonism traces back to the discovery of antibiotics, a paradigm shift happened when it was learned that protein secretion systems (e.g., types VI and IV secretion systems) deliver toxic "effectors" against competitors. However, a link between interbacterial antagonism and the Gram-negative type II secretion system (T2SS), which exists in many pathogens and environmental species, is not evident in prior reviews on bacterial competition or T2SS function. A current examination of the literature revealed four examples of a T2SS or one of its known substrates having a bactericidal activity against a Gram-positive target or another Gram-negative. When further studied, the T2SS effectors proved to be peptidases that target the peptidoglycan of the competitor. There are also reports of various bacteriolytic enzymes occurring in the culture supernatants of some other Gram-negative species, and a link between these bactericidal activities and T2SS is suggested. Thus, a T2SS can be a mediator of interbacterial antagonism, and it is possible that many T2SSs have antibacterial outputs. Yet, at present, the T2SS remains relatively understudied for its role in interbacterial competition. Arguably, there is a need to analyze the T2SSs of a broader range of species for their role in interbacterial antagonism. Such investigation offers, among other things, a possible pathway toward developing new antimicrobials for treating disease.
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Affiliation(s)
- Nicholas P Cianciotto
- Department of Microbiology-Immunology, Northwestern University School of Medicine, Chicago, Illinois, USA
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3
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Stoeltje L, Luc JK, Haddad T, Schrankel CS. The roles of ABCB1/P-glycoprotein drug transporters in regulating gut microbes and inflammation: insights from animal models, old and new. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230074. [PMID: 38497255 PMCID: PMC10945405 DOI: 10.1098/rstb.2023.0074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 02/13/2024] [Indexed: 03/19/2024] Open
Abstract
Commensal enteric bacteria have evolved systems that enable growth in the ecologic niche of the host gastrointestinal tract. Animals evolved parallel mechanisms to survive the constant exposure to bacteria and their metabolic by-products. We propose that drug transporters encompass a crucial system to managing the gut microbiome. Drug transporters are present in the apical surface of gut epithelia. They detoxify cells from small molecules and toxins (xenobiotics) in the lumen. Here, we review what is known about commensal structure in the absence of the transporter ABCB1/P-glycoprotein in mammalian models. Knockout or low-activity alleles of ABCB1 lead to dysbiosis, Crohn's disease and ulcerative colitis in mammals. However, the exact function of ABCB1 in these contexts remain unclear. We highlight emerging models-the zebrafish Danio rerio and sea urchin Lytechinus pictus-that are poised to help dissect the fundamental mechanisms of ATP-binding cassette (ABC) transporters in the tolerance of commensal and pathogenic communities in the gut. We and others hypothesize that ABCB1 plays a direct role in exporting inflammatory bacterial products from host epithelia. Interdisciplinary work in this research area will lend novel insight to the transporter-mediated pathways that impact microbiome community structure and accelerate the pathogenesis of inflammatory bowel disease when perturbed. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.
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Affiliation(s)
- Lauren Stoeltje
- Department of Biology, San Diego State University, 5500 Campanile Drive, Life Sciences North, Room 321, San Diego, CA 92182, USA
| | - Jenna K. Luc
- Department of Biology, San Diego State University, 5500 Campanile Drive, Life Sciences North, Room 321, San Diego, CA 92182, USA
| | - Timothaus Haddad
- Department of Biology, San Diego State University, 5500 Campanile Drive, Life Sciences North, Room 321, San Diego, CA 92182, USA
| | - Catherine S. Schrankel
- Department of Biology, San Diego State University, 5500 Campanile Drive, Life Sciences North, Room 321, San Diego, CA 92182, USA
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LeBlanc NR, Harrigian FC. Green Waste Compost Impacts Microbial Functions Related to Carbohydrate Use and Active Dispersal in Plant Pathogen-Infested Soil. MICROBIAL ECOLOGY 2024; 87:44. [PMID: 38367043 PMCID: PMC10874327 DOI: 10.1007/s00248-024-02361-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 02/13/2024] [Indexed: 02/19/2024]
Abstract
The effects of compost on physical and chemical characteristics of soil are well-studied but impacts on soil microbiomes are poorly understood. This research tested effects of green waste compost on bacterial communities in soil infested with the plant pathogen Fusarium oxysporum. Compost was added to pathogen-infested soil and maintained in mesocosms in a greenhouse experiment and replicated growth chamber experiments. Bacteria and F. oxysporum abundance were quantified using quantitative PCR. Taxonomic and functional characteristics of bacterial communities were measured using shotgun metagenome sequencing. Compost significantly increased bacterial abundance 8 weeks after amendment in one experiment. Compost increased concentrations of chemical characteristics of soil, including phosphorus, potassium, organic matter, and pH. In all experiments, compost significantly reduced abundance of F. oxysporum and altered the taxonomic composition of soil bacterial communities. Sixteen bacterial genera were significantly increased from compost in every experiment, potentially playing a role in pathogen suppression. In all experiments, there was a consistent negative effect of compost on functions related to carbohydrate use and a positive effect on bacteria with flagella. Results from this work demonstrate that compost can reduce the abundance of soilborne plant pathogens and raise questions about the role of microbes in plant pathogen suppression.
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Affiliation(s)
- Nicholas R LeBlanc
- United States Department of Agriculture, Agricultural Research Service, Crop Improvement and Protection Research Unit, 1636 E. Alisal St, Salinas, CA, 93905, USA.
| | - Fiona C Harrigian
- United States Department of Agriculture, Agricultural Research Service, Crop Improvement and Protection Research Unit, 1636 E. Alisal St, Salinas, CA, 93905, USA
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5
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Graham CI, MacMartin TL, de Kievit TR, Brassinga AKC. Molecular regulation of virulence in Legionella pneumophila. Mol Microbiol 2024; 121:167-195. [PMID: 37908155 DOI: 10.1111/mmi.15172] [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: 05/31/2023] [Revised: 09/15/2023] [Accepted: 09/17/2023] [Indexed: 11/02/2023]
Abstract
Legionella pneumophila is a gram-negative bacteria found in natural and anthropogenic aquatic environments such as evaporative cooling towers, where it reproduces as an intracellular parasite of cohabiting protozoa. If L. pneumophila is aerosolized and inhaled by a susceptible person, bacteria may colonize their alveolar macrophages causing the opportunistic pneumonia Legionnaires' disease. L. pneumophila utilizes an elaborate regulatory network to control virulence processes such as the Dot/Icm Type IV secretion system and effector repertoire, responding to changing nutritional cues as their host becomes depleted. The bacteria subsequently differentiate to a transmissive state that can survive in the environment until a replacement host is encountered and colonized. In this review, we discuss the lifecycle of L. pneumophila and the molecular regulatory network that senses nutritional depletion via the stringent response, a link to stationary phase-like metabolic changes via alternative sigma factors, and two-component systems that are homologous to stress sensors in other pathogens, to regulate differentiation between the intracellular replicative phase and more transmissible states. Together, we highlight how this prototypic intracellular pathogen offers enormous potential in understanding how molecular mechanisms enable intracellular parasitism and pathogenicity.
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Affiliation(s)
- Christopher I Graham
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Teassa L MacMartin
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Teresa R de Kievit
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Ann Karen C Brassinga
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, Manitoba, Canada
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Xi W, Zhang X, Zhu X, Wang J, Xue H, Pan H. Distribution patterns and influential factors of pathogenic bacteria in freshwater aquaculture sediments. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:16028-16047. [PMID: 38308166 DOI: 10.1007/s11356-024-31897-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/03/2024] [Indexed: 02/04/2024]
Abstract
Pathogenic bacteria, the major causative agents of aquaculture diseases, are a serious impediment to the aquaculture industry. However, the bioinformatics of pathogenic bacteria and virulence factors (VFs) in sediments, an important component of freshwater aquaculture ecosystems, are not well characterized. In this study, 20 sediment samples were collected from fish pond sediments (FPS), shrimp field sediments (SFS), fish pond sediment control (FPSC), and shrimp field sediment control (SFSC). Molecular biological information was obtained on a total of 173 pathogenic bacteria, 1093 virulence factors (VFs), and 8475 mobile genetic elements (MGEs) from these samples. The results indicated that (1) aquaculture patterns and sediment characteristics can affect the distribution of pathogenic bacteria. According to the results of the Kruskal-Wallis H test, except for Mycobacterium gilvum, there were significant differences (P < 0.05) among the four sediment types in the average abundance of major pathogenic bacteria (top 30 in abundance), and the average abundance of major pathogenic bacteria in the four sediment types followed the following pattern: FPS > SFS > FPSC > SFSC. (2) Pathogenic bacteria are able to implement a variety of complex pathogenic mechanisms such as adhesion, invasion, immune evasion, and metabolic regulation in the host because they carry a variety of VFs such as type IV pili, HSI-I, Alginate, Colibactin, and Capsule. According to the primary classification of the Virulence Factor Database (VFDB), the abundance of VFs in all four types of sediments showed the following pattern: offensive VFs > non-specific VFs > defensive VFs > regulation of virulence-related genes. (3) Total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), nitrite, and nitrate were mostly only weakly positively correlated with the major pathogenic bacteria and could promote the growth of pathogenic bacteria to some extent, whereas ammonia was significantly positively correlated with most of the major pathogenic bacteria and could play an important role in promoting the growth and reproduction of pathogenic bacteria. (4) Meanwhile, there was also a significant positive correlation between CAZyme genes and major pathogenic bacteria (0.62 ≤ R ≤ 0.89, P < 0.05). This suggests that these pathogenic bacteria could be the main carriers of CAZyme genes and, to some extent, gained a higher level of metabolic activity by degrading organic matter in the sediments to maintain their competitive advantage. (5) Worryingly, the results of correlation analyses indicated that MGEs in aquaculture sediments could play an important role in the spread of VFs (R = 0.82, P < 0.01), and in particular, plasmids (R = 0.75, P < 0.01) and integrative and conjugative elements (ICEs, R = 0.65, P < 0.05) could be these major vectors of VFs. The results of this study contribute to a comprehensive understanding of the health of freshwater aquaculture sediments and provide a scientific basis for aquaculture management and conservation.
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Affiliation(s)
- Wenxiang Xi
- Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan, 430100, Hubei, China
- College of Resources and Environment, Yangtze University, Wuhan, 430100, Hubei, China
| | - Xun Zhang
- China Coal Mine Construction Group Co., LTD, Hefei, 230071, Anhui, China
| | - Xianbin Zhu
- Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan, 430100, Hubei, China
- College of Resources and Environment, Yangtze University, Wuhan, 430100, Hubei, China
| | - Jiaming Wang
- Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan, 430100, Hubei, China
- College of Resources and Environment, Yangtze University, Wuhan, 430100, Hubei, China
| | - Han Xue
- Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan, 430100, Hubei, China
- College of Resources and Environment, Yangtze University, Wuhan, 430100, Hubei, China
| | - Hongzhong Pan
- Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan, 430100, Hubei, China.
- College of Resources and Environment, Yangtze University, Wuhan, 430100, Hubei, China.
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7
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Farci D, Milenkovic S, Iesu L, Tanas M, Ceccarelli M, Piano D. Structural characterization and functional insights into the type II secretion system of the poly-extremophile Deinococcus radiodurans. J Biol Chem 2024; 300:105537. [PMID: 38072042 PMCID: PMC10828601 DOI: 10.1016/j.jbc.2023.105537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/07/2023] [Accepted: 11/28/2023] [Indexed: 01/21/2024] Open
Abstract
The extremophile bacterium D. radiodurans boasts a distinctive cell envelope characterized by the regular arrangement of three protein complexes. Among these, the Type II Secretion System (T2SS) stands out as a pivotal structural component. We used cryo-electron microscopy to reveal unique features, such as an unconventional protein belt (DR_1364) around the main secretin (GspD), and a cap (DR_0940) found to be a separated subunit rather than integrated with GspD. Furthermore, a novel region at the N-terminus of the GspD constitutes an additional second gate, supplementing the one typically found in the outer membrane region. This T2SS was found to contribute to envelope integrity, while also playing a role in nucleic acid and nutrient trafficking. Studies on intact cell envelopes show a consistent T2SS structure repetition, highlighting its significance within the cellular framework.
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Affiliation(s)
- Domenica Farci
- Department of Plant Physiology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland; Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy; R&D Department, ReGenFix Laboratories, Sardara, Italy.
| | - Stefan Milenkovic
- Department of Physics and IOM/CNR, Università degli Studi di Cagliari, Monserrato, Italy
| | - Luca Iesu
- Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy
| | - Marta Tanas
- Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy
| | - Matteo Ceccarelli
- Department of Physics and IOM/CNR, Università degli Studi di Cagliari, Monserrato, Italy
| | - Dario Piano
- Department of Plant Physiology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland; Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy; R&D Department, ReGenFix Laboratories, Sardara, Italy.
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Krekhno Z, Woodward SE, Serapio-Palacios A, Peña-Díaz J, Moon KM, Foster LJ, Finlay BB. Citrobacter rodentium possesses a functional type II secretion system necessary for successful host infection. Gut Microbes 2024; 16:2308049. [PMID: 38299318 PMCID: PMC10841016 DOI: 10.1080/19490976.2024.2308049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/17/2024] [Indexed: 02/02/2024] Open
Abstract
Infectious diarrheal diseases are the third leading cause of mortality in young children, many of which are driven by Gram-negative bacterial pathogens. To establish successful host infections these pathogens employ a plethora of virulence factors necessary to compete with the resident microbiota, and evade and subvert the host defenses. The type II secretion system (T2SS) is one such conserved molecular machine that allows for the delivery of effector proteins into the extracellular milieu. To explore the role of the T2SS during natural host infection, we used Citrobacter rodentium, a murine enteric pathogen, as a model of human intestinal disease caused by pathogenic Escherichia coli such as Enteropathogenic and Enterohemorrhagic E. coli (EPEC and EHEC). In this study, we determined that the C. rodentium genome encodes one T2SS and 22 potential T2SS-secreted protein effectors, as predicted via sequence homology. We demonstrated that this system was functional in vitro, identifying a role in intestinal mucin degradation allowing for its utilization as a carbon source, and promoting C. rodentium attachment to a mucus-producing colon cell line. During host infection, loss of the T2SS or associated effectors led to a significant colonization defect and lack of systemic spread. In mice susceptible to lethal infection, T2SS-deficient C. rodentium was strongly attenuated, resulting in reduced morbidity and mortality in infected hosts. Together these data highlight the important role of the T2SS and its effector repertoire during C. rodentium pathogenesis, aiding in successful host mucosal colonization.
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Affiliation(s)
- Z Krekhno
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - SE Woodward
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - A Serapio-Palacios
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - J Peña-Díaz
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - KM Moon
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - LJ Foster
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - BB Finlay
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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9
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Maire J, Philip GK, Livingston J, Judd LM, Blackall LL, van Oppen MJH. Functional potential and evolutionary response to long-term heat selection of bacterial associates of coral photosymbionts. mSystems 2023; 8:e0086023. [PMID: 37909753 PMCID: PMC10746172 DOI: 10.1128/msystems.00860-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023] Open
Abstract
IMPORTANCE Symbiotic microorganisms are crucial for the survival of corals and their resistance to coral bleaching in the face of climate change. However, the impact of microbe-microbe interactions on coral functioning is mostly unknown but could be essential factors for coral adaption to future climates. Here, we investigated interactions between cultured dinoflagellates of the Symbiodiniaceae family, essential photosymbionts of corals, and associated bacteria. By assessing the genomic potential of 49 bacteria, we found that they are likely beneficial for Symbiodiniaceae, through the production of B vitamins and antioxidants. Additionally, bacterial genes involved in host-symbiont interactions, such as secretion systems, accumulated mutations following long-term exposure to heat, suggesting symbiotic interactions may change under climate change. This highlights the importance of microbe-microbe interactions in coral functioning.
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Affiliation(s)
- Justin Maire
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Gayle K. Philip
- Melbourne Bioinformatics, The University of Melbourne, Parkville, Victoria, Australia
| | - Jadzia Livingston
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Louise M. Judd
- Doherty Applied Microbial Genomics, Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria, Australia
| | - Linda L. Blackall
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Madeleine J. H. van Oppen
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
- Australian Institute of Marine Science, Townsville, Queensland, Australia
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10
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Gould AL, Henderson JB. Comparative genomics of symbiotic Photobacterium using highly contiguous genome assemblies from long read sequences. Microb Genom 2023; 9:001161. [PMID: 38112751 PMCID: PMC10763503 DOI: 10.1099/mgen.0.001161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 12/04/2023] [Indexed: 12/21/2023] Open
Abstract
This study presents the assembly and comparative genomic analysis of luminous Photobacterium strains isolated from the light organs of 12 fish species using Oxford Nanopore Technologies (ONT) sequencing. The majority of assemblies achieved chromosome-level continuity, consisting of one large (>3 Mbp) and one small (~1.5 Mbp) contig, with near complete BUSCO scores along with varying plasmid sequences. Leveraging this dataset, this study significantly expanded the available genomes for P. leiognathi and its subspecies P. 'mandapamensis', enabling a comparative genomic analysis between the two lineages. An analysis of the large and small chromosomes unveiled distinct patterns of core and accessory genes, with a larger fraction of the core genes residing on the large chromosome, supporting the hypothesis of secondary chromosome evolution from megaplasmids in Vibrionaceae. In addition, we discovered a proposed new species, Photobacterium acropomis sp. nov., isolated from an acropomatid host, with an average nucleotide identify (ANI) of 93 % compared to the P. leiognathi and P. 'mandapamensis' strains. A comparison of the P. leiognathi and P. 'mandapamensis' lineages revealed minimal differences in gene content, yet highlighted the former's larger genome size and potential for horizontal gene transfer. An investigation of the lux-rib operon, responsible for light production, indicated congruence between the presence of luxF and host family, challenging its role in differentiating P. 'mandapamensis' from P. leiognathi. Further insights were derived from the identification of metabolic differences, such as the presence of the NADH:quinone oxidoreductase respiratory complex I in P. leiognathi as well as variations in the type II secretion system (T2S) genes between the lineages, potentially impacting protein secretion and symbiosis. In summary, this study advances our understanding of Photobacterium genome evolution, highlighting subtle differences between closely related lineages, specifically P. leiognathi and P. 'mandapamensis'. These findings highlight the benefit of long read sequencing for bacterial genome assembly and pangenome analysis and provide a foundation for exploring early bacterial speciation processes of these facultative light organ symbionts.
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Affiliation(s)
- Alison L. Gould
- Institute for Biodiversity Science and Sustainability, California Academy of Sciences, 55 Music Concourse Dr. San Francisco, CA 94118, California, USA
| | - James B. Henderson
- Institute for Biodiversity Science and Sustainability, California Academy of Sciences, 55 Music Concourse Dr. San Francisco, CA 94118, California, USA
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11
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Barbat B, Douzi B, Ball G, Tribout M, El Karkouri K, Kellenberger C, Voulhoux R. Insights into dynamics and gating properties of T2SS secretins. SCIENCE ADVANCES 2023; 9:eadg6996. [PMID: 37792935 PMCID: PMC10550240 DOI: 10.1126/sciadv.adg6996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 09/05/2023] [Indexed: 10/06/2023]
Abstract
Secretins are outer membrane (OM) channels found in various bacterial nanomachines that secrete or assemble large extracellular structures. High-resolution 3D structures of type 2 secretion system (T2SS) secretins revealed bimodular channels with a C-module, holding a conserved central gate and an optional top gate, followed by an N-module for which multiple structural organizations have been proposed. Here, we perform a structure-driven in vivo study of the XcpD secretin, which validates one of the organizations of the N-module whose flexibility enables alternative conformations. We also show the existence of the central gate in vivo and its required flexibility, which is key for substrate passage and watertightness control. Last, functional, genomic, and phylogenetic analyses indicate that the optional top gate provides a gain of watertightness. Our data illustrate how the gating properties of T2SS secretins allow these large channels to overcome the duality between the necessity of preserving the OM impermeability while simultaneously promoting the secretion of large, folded effectors.
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Affiliation(s)
- Brice Barbat
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, Marseille, France
| | - Badreddine Douzi
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, Marseille, France
- Université de Lorraine, INRAE, DynAMic, Nancy, F-54000 France
| | - Geneviève Ball
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, Marseille, France
| | - Mathilde Tribout
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, Marseille, France
| | | | | | - Romé Voulhoux
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, Marseille, France
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12
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Li Y, Santos-Moreno J, Francetic O. The periplasmic coiled coil formed by the assembly platform proteins PulL and PulM is critical for function of the Klebsiella type II secretion system. Res Microbiol 2023; 174:104075. [PMID: 37141929 DOI: 10.1016/j.resmic.2023.104075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/06/2023]
Abstract
Bacteria use type II secretion systems (T2SS) to secrete to their surface folded proteins that confer diverse functions, from nutrient acquisition to virulence. In the Klebsiella species, T2SS-mediated secretion of pullulanase (PulA) requires assembly of a dynamic filament called the endopilus. The inner membrane assembly platform (AP) subcomplex is essential for endopilus assembly and PulA secretion. AP components PulL and PulM interact with each other through their C-terminal globular domains and transmembrane segments. Here, we investigated the roles of their periplasmic helices, predicted to form a coiled coil, in assembly and function of the PulL-PulM complex. PulL and PulM variants lacking these periplasmic helices were defective for interaction in the bacterial two-hybrid (BACTH) assay. Their functions in PulA secretion and assembly of PulG subunits into endopilus filaments were strongly reduced. Interestingly, deleting the cytoplasmic peptide of PulM nearly abolished the function of variant PulMΔN and its interaction with PulG, but not with PulL, in the BACTH assay. Nevertheless, PulL was specifically proteolyzed in the presence of the PulMΔN variant, suggesting that PulM N-terminal peptide stabilizes PulL in the cytoplasm. We discuss the implications of these results for the T2S endopilus and type IV pilus assembly mechanisms.
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Affiliation(s)
- Yuanyuan Li
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| | - Javier Santos-Moreno
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
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13
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Wein P, Dornblut K, Herkersdorf S, Krüger T, Molloy EM, Brakhage AA, Hoffmeister D, Hertweck C. Bacterial secretion systems contribute to rapid tissue decay in button mushroom soft rot disease. mBio 2023; 14:e0078723. [PMID: 37486262 PMCID: PMC10470514 DOI: 10.1128/mbio.00787-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/08/2023] [Indexed: 07/25/2023] Open
Abstract
The soft rot pathogen Janthinobacterium agaricidamnosum causes devastating damage to button mushrooms (Agaricus bisporus), one of the most cultivated and commercially relevant mushrooms. We previously discovered that this pathogen releases the membrane-disrupting lipopeptide jagaricin. This bacterial toxin, however, could not solely explain the rapid decay of mushroom fruiting bodies, indicating that J. agaricidamnosum implements a more sophisticated infection strategy. In this study, we show that secretion systems play a crucial role in soft rot disease. By mining the genome of J. agaricidamnosum, we identified gene clusters encoding a type I (T1SS), a type II (T2SS), a type III (T3SS), and two type VI secretion systems (T6SSs). We targeted the T2SS and T3SS for gene inactivation studies, and subsequent bioassays implicated both in soft rot disease. Furthermore, through a combination of comparative secretome analysis and activity-guided fractionation, we identified a number of secreted lytic enzymes responsible for mushroom damage. Our findings regarding the contribution of secretion systems to the disease process expand the current knowledge of bacterial soft rot pathogens and represent a significant stride toward identifying targets for their disarmament with secretion system inhibitors. IMPORTANCE The button mushroom (Agaricus bisporus) is the most popular edible mushroom in the Western world. However, mushroom crops can fall victim to serious bacterial diseases that are a major threat to the mushroom industry, among them being soft rot disease caused by Janthinobacterium agaricidamnosum. Here, we show that the rapid dissolution of mushroom fruiting bodies after bacterial invasion is due to degradative enzymes and putative effector proteins secreted via the type II secretion system (T2SS) and the type III secretion system (T3SS), respectively. The ability to degrade mushroom tissue is significantly attenuated in secretion-deficient mutants, which establishes that secretion systems are key factors in mushroom soft rot disease. This insight is of both ecological and agricultural relevance by shedding light on the disease processes behind a pathogenic bacterial-fungal interaction which, in turn, serves as a starting point for the development of secretion system inhibitors to control disease progression.
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Affiliation(s)
- Philipp Wein
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Katharina Dornblut
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Sebastian Herkersdorf
- Department of Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Friedrich Schiller University Jena, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Thomas Krüger
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Evelyn M. Molloy
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Axel A. Brakhage
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
| | - Dirk Hoffmeister
- Department of Pharmaceutical Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Friedrich Schiller University Jena, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
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14
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Yu Z, Wu Y, Chen M, Huo T, Zheng W, Ludtke SJ, Shi X, Wang Z. Membrane translocation process revealed by in situ structures of type II secretion system secretins. Nat Commun 2023; 14:4025. [PMID: 37419909 PMCID: PMC10329019 DOI: 10.1038/s41467-023-39583-2] [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: 02/22/2023] [Accepted: 06/20/2023] [Indexed: 07/09/2023] Open
Abstract
The GspD secretin is the outer membrane channel of the bacterial type II secretion system (T2SS) which secrets diverse toxins that cause severe diseases such as diarrhea and cholera. GspD needs to translocate from the inner to the outer membrane to exert its function, and this process is an essential step for T2SS to assemble. Here, we investigate two types of secretins discovered so far in Escherichia coli, GspDα, and GspDβ. By electron cryotomography subtomogram averaging, we determine in situ structures of key intermediate states of GspDα and GspDβ in the translocation process, with resolution ranging from 9 Å to 19 Å. In our results, GspDα and GspDβ present entirely different membrane interaction patterns and ways of transitioning the peptidoglycan layer. From this, we hypothesize two distinct models for the membrane translocation of GspDα and GspDβ, providing a comprehensive perspective on the inner to outer membrane biogenesis of T2SS secretins.
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Affiliation(s)
- Zhili Yu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yaoming Wu
- Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Muyuan Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, 94025, USA
| | - Tong Huo
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Wei Zheng
- Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Steven J Ludtke
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Cryo Electron Microscopy and Tomography Core, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Xiaodong Shi
- Jiangsu Province Key Laboratory of Anesthesiology and Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China.
| | - Zhao Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
- Cryo Electron Microscopy and Tomography Core, Baylor College of Medicine, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
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15
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Vlaanderen EJ, Ghaly TM, Moore LR, Focardi A, Paulsen IT, Tetu SG. Plastic leachate exposure drives antibiotic resistance and virulence in marine bacterial communities. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 327:121558. [PMID: 37019264 DOI: 10.1016/j.envpol.2023.121558] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/14/2023] [Accepted: 04/02/2023] [Indexed: 06/19/2023]
Abstract
Plastic pollution is a serious global problem, with more than 12 million tonnes of plastic waste entering the oceans every year. Plastic debris can have considerable impacts on microbial community structure and functions in marine environments, and has been associated with an enrichment in pathogenic bacteria and antimicrobial resistance (AMR) genes. However, our understanding of these impacts is largely restricted to microbial assemblages on plastic surfaces. It is therefore unclear whether these effects are driven by the surface properties of plastics, providing an additional niche for certain microbes residing in biofilms, and/or chemicals leached from plastics, the effects of which could extend to surrounding planktonic bacteria. Here, we examine the effects of polyvinyl chloride (PVC) plastic leachate exposure on the relative abundance of genes associated with bacterial pathogenicity and AMR within a seawater microcosm community. We show that PVC leachate, in the absence of plastic surfaces, drives an enrichment in AMR and virulence genes. In particular, leachate exposure significantly enriches AMR genes that confer multidrug, aminoglycoside and peptide antibiotic resistance. Additionally, enrichment of genes involved in the extracellular secretion of virulence proteins was observed among pathogens of marine organisms. This study provides the first evidence that chemicals leached from plastic particles alone can enrich genes related to microbial pathogenesis within a bacterial community, expanding our knowledge of the environmental impacts of plastic pollution with potential consequences for human and ecosystem health.
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Affiliation(s)
- Eric J Vlaanderen
- College of Science and Engineering, James Cook University, Townsville, Australia
| | - Timothy M Ghaly
- School of Natural Sciences Macquarie University, Sydney, Australia; ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
| | - Lisa R Moore
- School of Natural Sciences Macquarie University, Sydney, Australia
| | - Amaranta Focardi
- Climate Change Cluster (C3), University of Technology Sydney, Sydney, Australia
| | - Ian T Paulsen
- School of Natural Sciences Macquarie University, Sydney, Australia; ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
| | - Sasha G Tetu
- School of Natural Sciences Macquarie University, Sydney, Australia; ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia.
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16
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NandaKafle G, Blasius LA, Seale T, Brözel VS. Escherichia coli Strains Display Varying Susceptibility to Grazing by the Soil Amoeba Dictyostelium discoideum. Microorganisms 2023; 11:1457. [PMID: 37374960 DOI: 10.3390/microorganisms11061457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 05/23/2023] [Accepted: 05/30/2023] [Indexed: 06/29/2023] Open
Abstract
Recent studies have shown that Escherichia coli can survive in different environments, including soils, and they can maintain populations in sterile soil for a long period of time. This indicates that growth-supporting nutrients are available; however, when grown in non-sterile soils, populations decline, suggesting that other biological factors play a role in controlling E. coli populations in soil. Free-living protozoa can affect the bacterial population by grazing. We hypothesized that E. coli strains capable of surviving in non-sterile soil possess mechanisms to protect themselves from amoeba predation. We determined the grazing rate of E. coli pasture isolates by using Dictyostelium discoideum. Bacterial suspensions applied to lactose agar as lines were allowed to grow for 24 h, when 4 μL of D. discoideum culture was inoculated in the center of each bacterial line. Grazing distances were measured after 4 days. The genomes of five grazing-susceptible and five grazing-resistant isolates were sequenced and compared. Grazing distance varied among isolates, which indicated that some E. coli are more susceptible to grazing by protozoa than others. When presented with a choice between grazing-susceptible and grazing-resistant isolates, D. discoideum grazed only on the susceptible strain. Grazing susceptibility phenotype did not align with the phylogroup, with both B1 and E strains found in both grazing groups. They also did not align by core genome phylogeny. Whole genome comparisons revealed that the five most highly grazed strains had 389 shared genes not found in the five least grazed strains. Conversely, the five least grazed strains shared 130 unique genes. The results indicate that long-term persistence of E. coli in soil is due at least in part to resistance to grazing by soil amoeba.
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Affiliation(s)
- Gitanjali NandaKafle
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57006, USA
| | - Lane A Blasius
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57006, USA
| | - Tarren Seale
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0004, South Africa
| | - Volker S Brözel
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57006, USA
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0004, South Africa
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17
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Nguyen M, Wu TH, Danielson K, Khan N, Zhang J, Craig L. Mechanism of secretion of TcpF by the Vibrio cholerae toxin-coregulated pilus. Proc Natl Acad Sci U S A 2023; 120:e2212664120. [PMID: 37040409 PMCID: PMC10120004 DOI: 10.1073/pnas.2212664120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 02/28/2023] [Indexed: 04/12/2023] Open
Abstract
Many bacteria possess dynamic filaments called Type IV pili (T4P) that perform diverse functions in colonization and dissemination, including host cell adhesion, DNA uptake, and secretion of protein substrates-exoproteins-from the periplasm to the extracellular space. The Vibrio cholerae toxin-coregulated pilus (TCP) and the enterotoxigenic Escherichia coli CFA/III pilus each mediates export of a single exoprotein, TcpF and CofJ, respectively. Here, we show that the disordered N-terminal segment of mature TcpF is the export signal (ES) recognized by TCP. Deletion of the ES disrupts secretion and causes TcpF to accumulate in the V. cholerae periplasm. The ES alone can mediate export of Neisseria gonorrhoeae FbpA by V. cholerae in a T4P-dependent manner. The ES is specific for its autologous T4P machinery as CofJ bearing the TcpF ES is exported by V. cholerae, whereas TcpF bearing the CofJ ES is not. Specificity is mediated by binding of the ES to TcpB, a minor pilin that primes pilus assembly and forms a trimer at the pilus tip. Finally, the ES is proteolyzed from the mature TcpF protein upon secretion. Together, these results provide a mechanism for delivery of TcpF across the outer membrane and release into the extracellular space.
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Affiliation(s)
- Minh Nguyen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Tzu-Hui Wu
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Katie J. Danielson
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Nabeel M. Khan
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - John Zhijia Zhang
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Lisa Craig
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
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18
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Maphosa S, Moleleki LN, Motaung TE. Bacterial secretion system functions: evidence of interactions and downstream implications. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 37083586 DOI: 10.1099/mic.0.001326] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Unprecedented insights into the biology and functions of bacteria have been and continue to be gained through studying bacterial secretion systems in isolation. This method, however, results in our understanding of the systems being primarily based on the idea that they operate independently, ignoring the subtleties of downstream interconnections. Gram-negative bacteria are naturally able to adapt to and navigate their frequently varied and dynamic surroundings, mostly because of the covert connections between secretion systems. Therefore, to comprehend some of the linked downstream repercussions for organisms that follow this discourse, it is vital to have mechanistic insights into how the intersecretion system functions in bacterial rivalry, virulence, and survival, among other things. To that purpose, this paper discusses a few key instances of molecular antagonistic and interdependent relationships between bacterial secretion systems and their produced functional products.
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Affiliation(s)
- Silindile Maphosa
- Division of Microbiology, Department of Biochemistry, Genetics, and Microbiology, University of Pretoria, Hatfield, Pretoria, South Africa
- Department of Plant and Soil Sciences, University of Pretoria, Hatfield, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Hatfield, Pretoria, South Africa
| | - Lucy N Moleleki
- Division of Microbiology, Department of Biochemistry, Genetics, and Microbiology, University of Pretoria, Hatfield, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Hatfield, Pretoria, South Africa
| | - Thabiso E Motaung
- Division of Microbiology, Department of Biochemistry, Genetics, and Microbiology, University of Pretoria, Hatfield, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Hatfield, Pretoria, South Africa
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19
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Shaliutina-Loginova A, Francetic O, Doležal P. Bacterial Type II Secretion System and Its Mitochondrial Counterpart. mBio 2023; 14:e0314522. [PMID: 36971557 PMCID: PMC10128026 DOI: 10.1128/mbio.03145-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
Over the billions of years that bacteria have been around, they have evolved several sophisticated protein secretion nanomachines to deliver toxins, hydrolytic enzymes, and effector proteins into their environments. Of these, the type II secretion system (T2SS) is used by Gram-negative bacteria to export a wide range of folded proteins from the periplasm across the outer membrane.
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20
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Akinduti PA, George OW, Ohore HU, Ariyo OE, Popoola ST, Adeleye AI, Akinwande KS, Popoola JO, Rotimi SO, Olufemi FO, Omonhinmin CA, Olasehinde GI. Evaluation of Efflux-Mediated Resistance and Biofilm formation in Virulent Pseudomonas aeruginosa Associated with Healthcare Infections. Antibiotics (Basel) 2023; 12:antibiotics12030626. [PMID: 36978493 PMCID: PMC10044907 DOI: 10.3390/antibiotics12030626] [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: 06/16/2022] [Revised: 07/19/2022] [Accepted: 07/29/2022] [Indexed: 03/30/2023] Open
Abstract
Pseudomonas aeruginosa is a significant pathogen identified with healthcare-associated infections. The present study evaluates the role of biofilm and efflux pump activities in influencing high-level resistance in virulent P. aeruginosa strains in clinical infection. Phenotypic resistance in biotyped Pseudomonas aeruginosa (n = 147) from diagnosed disease conditions was classified based on multiple antibiotic resistance (MAR) indices and analysed with logistic regression for risk factors. Efflux pump activity, biofilm formation, and virulence factors were analysed for optimal association in Pseudomonas infection using receiver operation characteristics (ROC). Age-specificity (OR [CI] = 0.986 [0.946-1.027]), gender (OR [CI] = 1.44 [0.211-9.827]) and infection sources (OR [CI] = 0.860 [0.438-1.688]) were risk variables for multidrug resistance (MDR)-P. aeruginosa infection (p < 0.05). Biofilm formers caused 48.2% and 18.5% otorrhea and wound infections (95% CI = 0.820-1.032; p = 0.001) respectively and more than 30% multidrug resistance (MDR) strains demonstrated high-level efflux pump activity (95% CI = 0.762-1.016; p = 0.001), protease (95% CI = 0.112-0.480; p = 0.003), lipase (95% CI = 0.143-0.523; p = 0.001), and hemolysin (95% CI = 1.109-1.780; p = 0.001). Resistance relatedness of more than 80% and 60% to cell wall biosynthesis inhibitors (ceftazidime, ceffproxil, augumentin, ampicillin) and, DNA translational and transcriptional inhibitors (gentamicin, ciprofloxacin, ofloxacin, nitrofurantoin) were observed (p < 0.05). Strong efflux correlation (r = 0.85, p = 0.034) with MDR strains, with high predictive performances in efflux pump activity (ROC-AUC 0.78), biofilm formation (ROC-AUC 0.520), and virulence hierarchical-clustering. Combine activities of the expressed efflux pump and biofilm formation in MDR-P. aeruginosa pose risk to clinical management and infection control.
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Affiliation(s)
- Paul A Akinduti
- Microbiology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | - Onome W George
- Microbiology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | - Hannah U Ohore
- Microbiology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | | | - Samuel T Popoola
- Microbiology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | - Adenike I Adeleye
- Veterinary Teaching Hospital, Federal University of Agriculture, Abeokuta 110124, Ogun State, Nigeria
| | - Kazeem S Akinwande
- Department of Chemical Pathology and Immunology, Federal Medical Centre, Abeokuta 110124, Ogun State, Nigeria
| | - Jacob O Popoola
- Applied Biology and Biotechnology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | - Solomon O Rotimi
- Department of Biochemistry and Molecular Biology, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | - Fredrick O Olufemi
- Department of Veterinary Microbiology and Virology, College of Veterinary Medicine, Federal University of Agriculture, Abeokuta 110124, Ogun State, Nigeria
| | - Conrad A Omonhinmin
- Applied Biology and Biotechnology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
| | - Grace I Olasehinde
- Microbiology Unit, Department of Biological Sciences, Covenant University, PMB 1023, Ota 112104, Ogun State, Nigeria
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21
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Weisse L, Héchard Y, Moumen B, Delafont V. Here, there and everywhere: Ecology and biology of the Dependentiae phylum. Environ Microbiol 2023; 25:597-605. [PMID: 36510838 DOI: 10.1111/1462-2920.16307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
Our view of bacterial diversity has been dramatically impacted by cultivation-independent approaches such as metagenomics and 16S rRNA gene sequencing. Consequently, most bacterial phyla known to date are only documented by the presence of DNA sequences in databases and lack cultivated representatives. This bacterial majority that is yet-to-be cultivated, is forming the 'Microbial Dark Matter', (MDM) a consortium, whose ecology and biology remain largely unexplored. The Candidatus Dependentiae stands as one of many phyla within this MDM, found worldwide in various environments. Genomic evidence suggests ancestral, unusual adaptations of all Ca. Dependentiae to a host dependent lifestyle. In line with this, protists appear to be important for Ca. Dependentiae biology, as revealed by few recent studies, which enabled their growth in laboratory through host cultivation. However, the Ca. Dependentiae still remain to this day a poorly documented phylum. The present review aims to summarize the current knowledge accumulated on this often found, but rarely highlighted, bacterial phylum.
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Affiliation(s)
- Louis Weisse
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, CNRS UMR 7267, Poitiers, France
| | - Yann Héchard
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, CNRS UMR 7267, Poitiers, France
| | - Bouziane Moumen
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, CNRS UMR 7267, Poitiers, France
| | - Vincent Delafont
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, CNRS UMR 7267, Poitiers, France
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22
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Dazzoni R, Li Y, López-Castilla A, Brier S, Mechaly A, Cordier F, Haouz A, Nilges M, Francetic O, Bardiaux B, Izadi-Pruneyre N. Structure and dynamic association of an assembly platform subcomplex of the bacterial type II secretion system. Structure 2023; 31:152-165.e7. [PMID: 36586404 DOI: 10.1016/j.str.2022.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/20/2022] [Accepted: 11/29/2022] [Indexed: 12/31/2022]
Abstract
Type II secretion systems (T2SSs) allow diderm bacteria to secrete hydrolytic enzymes, adhesins, or toxins important for growth and virulence. To promote secretion of folded proteins, T2SSs assemble periplasmic filaments called pseudopili or endopili at an inner membrane subcomplex, the assembly platform (AP). Here, we combined biophysical approaches, nuclear magnetic resonance (NMR) and X-ray crystallography, to study the Klebsiella AP components PulL and PulM. We determined the structure and associations of their periplasmic domains and describe the structure of the heterodimer formed by their ferredoxin-like domains. We show how structural complementarity and plasticity favor their association during the secretion process. Cysteine scanning and crosslinking data provided additional constraints to build a structural model of the PulL-PulM assembly in the cellular context. Our structural and functional insights, together with the relative cellular abundance of its components, support the role of AP as a dynamic hub that orchestrates pilus polymerization.
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Affiliation(s)
- Régine Dazzoni
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France
| | - Yuanyuan Li
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France
| | - Aracelys López-Castilla
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France
| | - Sébastien Brier
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Ariel Mechaly
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Crystallography Platform, 75015 Paris, France
| | - Florence Cordier
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Ahmed Haouz
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Crystallography Platform, 75015 Paris, France
| | - Michael Nilges
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Bacterial Transmembrane Systems Unit, 75015 Paris.
| | - Nadia Izadi-Pruneyre
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Bacterial Transmembrane Systems Unit, 75015 Paris.
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23
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LeBlanc N. Green Manures Alter Taxonomic and Functional Characteristics of Soil Bacterial Communities. MICROBIAL ECOLOGY 2023; 85:684-697. [PMID: 35112152 DOI: 10.1007/s00248-022-01975-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
Incorporation of plant biomass into soil as green manures can reduce soilborne diseases and improve crop and soil health in agricultural ecosystems. Soil microbial communities can mediate beneficial effects of these amendments, but their response to different types of green manures is poorly understood. This study tested the effect of green manures from broccoli, marigold, and sudangrass on taxonomic and functional characteristics of soil bacterial communities. Green manures were amended to field soil and maintained in microcosms artificially infested with the soilborne plant pathogen Verticillium dahliae. Lettuce seedlings were transplanted into green manure amended and fallow soil and maintained under growth chamber conditions for 12 weeks. Bacterial communities in bulk and rhizosphere soils were characterized using nanopore sequencing of 16S rRNA and shotgun metagenome libraries. Under microcosm conditions, all green manures reduced the abundance of the soilborne plant pathogen V. dahliae and altered the taxonomic composition of bacterial communities. Twelve weeks following amendment, green manures had differential effects on lettuce yield as well as the taxonomic diversity and composition of soil bacterial communities. In addition, multiple green manures increased the abundance of bacterial functional traits in rhizosphere soil related to iron and polysaccharide acquisition and decreased the abundance of functional traits related to bacterial protein secretion systems. This study demonstrates green manures alter the taxonomic composition and functional traits in soil bacterial communities suggesting these changes may impact beneficial effects of green manures on plant and soil health.
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Affiliation(s)
- Nicholas LeBlanc
- United States Department of Agriculture, Agricultural Research Service, Crop Improvement and Protection Research Unit, 1636 E. Alisal St., Salinas, CA, 93905, USA.
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24
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Barak-Gavish N, Dassa B, Kuhlisch C, Nussbaum I, Brandis A, Rosenberg G, Avraham R, Vardi A. Bacterial lifestyle switch in response to algal metabolites. eLife 2023; 12:e84400. [PMID: 36691727 PMCID: PMC9873259 DOI: 10.7554/elife.84400] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/05/2023] [Indexed: 01/19/2023] Open
Abstract
Unicellular algae, termed phytoplankton, greatly impact the marine environment by serving as the basis of marine food webs and by playing central roles in the biogeochemical cycling of elements. The interactions between phytoplankton and heterotrophic bacteria affect the fitness of both partners. It is becoming increasingly recognized that metabolic exchange determines the nature of such interactions, but the underlying molecular mechanisms remain underexplored. Here, we investigated the molecular and metabolic basis for the bacterial lifestyle switch, from coexistence to pathogenicity, in Sulfitobacter D7 during its interaction with Emiliania huxleyi, a cosmopolitan bloom-forming phytoplankter. To unravel the bacterial lifestyle switch, we analyzed bacterial transcriptomes in response to exudates derived from algae in exponential growth and stationary phase, which supported the Sulfitobacter D7 coexistence and pathogenicity lifestyles, respectively. In pathogenic mode, Sulfitobacter D7 upregulated flagellar motility and diverse transport systems, presumably to maximize assimilation of E. huxleyi-derived metabolites released by algal cells upon cell death. Algal dimethylsulfoniopropionate (DMSP) was a pivotal signaling molecule that mediated the transition between the lifestyles, supporting our previous findings. However, the coexisting and pathogenic lifestyles were evident only in the presence of additional algal metabolites. Specifically, we discovered that algae-produced benzoate promoted the growth of Sulfitobacter D7 and hindered the DMSP-induced lifestyle switch to pathogenicity, demonstrating that benzoate is important for maintaining the coexistence of algae and bacteria. We propose that bacteria can sense the physiological state of the algal host through changes in the metabolic composition, which will determine the bacterial lifestyle during interaction.
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Affiliation(s)
- Noa Barak-Gavish
- Department of Plant and Environmental Sciences, Weizmann Institute of ScienceRehovotIsrael
| | - Bareket Dassa
- Life Sciences Core Facilities, Weizmann Institute of ScienceRehovotIsrael
| | - Constanze Kuhlisch
- Department of Plant and Environmental Sciences, Weizmann Institute of ScienceRehovotIsrael
| | - Inbal Nussbaum
- Department of Plant and Environmental Sciences, Weizmann Institute of ScienceRehovotIsrael
| | - Alexander Brandis
- Life Sciences Core Facilities, Weizmann Institute of ScienceRehovotIsrael
| | - Gili Rosenberg
- Department of Biological Regulation, Weizmann Institute of ScienceRehovotIsrael
| | - Roi Avraham
- Department of Biological Regulation, Weizmann Institute of ScienceRehovotIsrael
| | - Assaf Vardi
- Department of Plant and Environmental Sciences, Weizmann Institute of ScienceRehovotIsrael
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25
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Wang C, Xiao Y, Wang Y, Liu Y, Yao Q, Zhu H. Comparative genomics and transcriptomics insight into myxobacterial metabolism potentials and multiple predatory strategies. Front Microbiol 2023; 14:1146523. [PMID: 37213496 PMCID: PMC10196010 DOI: 10.3389/fmicb.2023.1146523] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 04/19/2023] [Indexed: 05/23/2023] Open
Abstract
Myxobacteria are part of the phylum Myxococcota, encompassing four orders. Most of them display complex lifestyles and broad predation profiles. However, metabolic potential and predation mechanisms of different myxobacteria remains poorly understood. Herein, we used comparative genomics and transcriptomics to analyze metabolic potentials and differentially expressed gene (DEG) profiles of Myxococcus xanthus monoculture (Mx) compared to coculture with Escherichia coli (MxE) and Micrococcus luteus (MxM) prey. The results showed that myxobacteria had conspicuous metabolic deficiencies, various protein secretion systems (PSSs) and the common type II secretion system (T2SS). RNA-seq data demonstrated that M. xanthus overexpressed the potential predation DEGs, particularly those encoding T2SS, the tight adherence (Tad) pilus, different secondary metabolites (myxochelin A/B, myxoprincomide, myxovirescin A1, geosmin and myxalamide), glycosyl transferases and peptidase during predation. Furthermore, the myxalamide biosynthesis gene clusters, two hypothetical gene clusters and one arginine biosynthesis clusters were highly differential expressed in MxE versus MxM. Additionally, homologue proteins of the Tad (kil) system and five secondary metabolites were in different obligate or facultative predators. Finally, we provided a working model for exhibiting multiple predatory strategies when M. xanthus prey on M. luteus and E. coli. These results might spur application-oriented research on the development of novel antibacterial strategies.
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Affiliation(s)
- Chunling Wang
- College of Life Science, Huizhou University, Huizhou, Guangdong, China
- Key Laboratory of Agricultural Microbiomics and Precision Application (MARA), Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Key Laboratory of Agricultural Microbiome (MARA), State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, Guangdong, China
| | - Yi Xiao
- Key Laboratory of Agricultural Microbiomics and Precision Application (MARA), Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Key Laboratory of Agricultural Microbiome (MARA), State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, Guangdong, China
| | - Yong Wang
- Key Laboratory of Agricultural Microbiomics and Precision Application (MARA), Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Key Laboratory of Agricultural Microbiome (MARA), State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, Guangdong, China
| | - Yumin Liu
- Key Laboratory of Agricultural Microbiomics and Precision Application (MARA), Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Key Laboratory of Agricultural Microbiome (MARA), State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, Guangdong, China
| | - Qing Yao
- College of Horticulture, South China Agricultural University, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Guangzhou, Guangdong, China
| | - Honghui Zhu
- Key Laboratory of Agricultural Microbiomics and Precision Application (MARA), Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Key Laboratory of Agricultural Microbiome (MARA), State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, Guangdong, China
- *Correspondence: Honghui Zhu,
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Ganesan R, Wierz JC, Kaltenpoth M, Flórez LV. How It All Begins: Bacterial Factors Mediating the Colonization of Invertebrate Hosts by Beneficial Symbionts. Microbiol Mol Biol Rev 2022; 86:e0012621. [PMID: 36301103 PMCID: PMC9769632 DOI: 10.1128/mmbr.00126-21] [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] [Indexed: 01/01/2023] Open
Abstract
Beneficial associations with bacteria are widespread across animals, spanning a range of symbiont localizations, transmission routes, and functions. While some of these associations have evolved into obligate relationships with permanent symbiont localization within the host, the majority require colonization of every host generation from the environment or via maternal provisions. Across the broad diversity of host species and tissue types that beneficial bacteria can colonize, there are some highly specialized strategies for establishment yet also some common patterns in the molecular basis of colonization. This review focuses on the mechanisms underlying the early stage of beneficial bacterium-invertebrate associations, from initial contact to the establishment of the symbionts in a specific location of the host's body. We first reflect on general selective pressures that can drive the transition from a free-living to a host-associated lifestyle in bacteria. We then cover bacterial molecular factors for colonization in symbioses from both model and nonmodel invertebrate systems where these have been studied, including terrestrial and aquatic host taxa. Finally, we discuss how interactions between multiple colonizing bacteria and priority effects can influence colonization. Taking the bacterial perspective, we emphasize the importance of developing new experimentally tractable systems to derive general insights into the ecological factors and molecular adaptations underlying the origin and establishment of beneficial symbioses in animals.
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Affiliation(s)
- Ramya Ganesan
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Jürgen C. Wierz
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Laura V. Flórez
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Plant and Environmental Sciences, Section for Organismal Biology, University of Copenhagen, Copenhagen, Denmark
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27
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Yan J, Guo X, Li J, Li Y, Sun H, Li A, Cao B. RpoN is required for the motility and contributes to the killing ability of Plesiomonas shigelloides. BMC Microbiol 2022; 22:299. [PMID: 36510135 PMCID: PMC9743648 DOI: 10.1186/s12866-022-02722-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/30/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND RpoN, also known as σ54, first reported in Escherichia coli, is a subunit of RNA polymerase that strictly controls the expression of different genes by identifying specific promoter elements. RpoN has an important regulatory function in carbon and nitrogen metabolism and participates in the regulation of flagellar synthesis, bacterial motility and virulence. However, little is known about the effect of RpoN in Plesiomonas shigelloides. RESULTS To identify pathways controlled by RpoN, RNA sequencing (RNA-Seq) of the WT and the rpoN deletion strain was carried out for comparison. The RNA-seq results showed that RpoN regulates ~ 13.2% of the P. shigelloides transcriptome, involves amino acid transport and metabolism, glycerophospholipid metabolism, pantothenate and CoA biosynthesis, ribosome biosynthesis, flagellar assembly and bacterial secretion system. Furthermore, we verified the results of RNA-seq using quantitative real-time reverse transcription PCR, which indicated that the absence of rpoN caused downregulation of more than half of the polar and lateral flagella genes in P. shigelloides, and the ΔrpoN mutant was also non-motile and lacked flagella. In the present study, the ability of the ΔrpoN mutant to kill E. coli MG1655 was reduced by 54.6% compared with that of the WT, which was consistent with results in RNA-seq, which showed that the type II secretion system (T2SS-2) genes and the type VI secretion system (T6SS) genes were repressed. By contrast, the expression of type III secretion system genes was largely unchanged in the ΔrpoN mutant transcriptome and the ability of the ΔrpoN mutant to infect Caco-2 cells was also not significantly different compared with the WT. CONCLUSIONS We showed that RpoN is required for the motility and contributes to the killing ability of P. shigelloides and positively regulates the T6SS and T2SS-2 genes.
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Affiliation(s)
- Junxiang Yan
- grid.216938.70000 0000 9878 7032TEDA Institute of Biological Sciences and Biotechnology, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China
| | - Xueqian Guo
- grid.216938.70000 0000 9878 7032TEDA Institute of Biological Sciences and Biotechnology, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China
| | - Jinghao Li
- grid.216938.70000 0000 9878 7032TEDA Institute of Biological Sciences and Biotechnology, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China
| | - Yuehua Li
- grid.216938.70000 0000 9878 7032TEDA Institute of Biological Sciences and Biotechnology, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China
| | - Hongmin Sun
- grid.216938.70000 0000 9878 7032TEDA Institute of Biological Sciences and Biotechnology, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China
| | - Ang Li
- grid.216938.70000 0000 9878 7032State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin, 300353 China
| | - Boyang Cao
- grid.216938.70000 0000 9878 7032TEDA Institute of Biological Sciences and Biotechnology, Nankai University, No.23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China ,grid.216938.70000 0000 9878 7032Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, No. 23, Hongda StreetTianjin Economic and Technological Development Area, Tianjin, 300457 China
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28
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Yi X, Xu X, Qi X, Chen Y, Zhu Z, Xu G, Li H, Kraco EK, Shen H, Lin M, Zheng J, Qin Y, Jiang X. Mechanisms Underlying the Virulence Regulation of Vibrio alginolyticus ND-01 pstS and pstB with a Transcriptomic Analysis. Microorganisms 2022; 10:2093. [PMID: 36363689 PMCID: PMC9698627 DOI: 10.3390/microorganisms10112093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/14/2022] [Accepted: 10/18/2022] [Indexed: 05/18/2024] Open
Abstract
Vibrio alginolyticus is a common opportunistic pathogen of fish, shrimp, and shellfish, and many diseases it causes can result in severe economic losses in the aquaculture industry. Causing host disease was confirmed by several virulence factors of V. alginolyticus. To date, there have been no reports on the effect of the pstS gene on its virulence regulation of V. alginolyticus. The virulence mechanism of target genes regulating V. alginolyticus is worthy of further study. Previous studies found that Fructus schisandrae (30 mg/mL) inhibited the growth of V. alginolyticus ND-01 (OD600 = 0.5) for 4 h, while the expressions of pstS and pstB were significantly affected by F. schisandrae stress. So, we speculated that pstS and pstB might be the virulence genes of V. alginolyticus, which were stably silenced by RNAi to construct the silencing strains pstS-RNAi and pstB-RNAi, respectively. After the expression of pstS or pstB gene was inhibited, the adhesion capacity and biofilm formation of V. alginolyticus were significantly down-regulated. The chemotaxis and biofilm formation ability of pstS-RNAi was reduced by 33.33% and 68.13% compared with the wild-type strain, respectively. Sequence alignment and homology analysis showed that pstS was highly conserved, which suggested that pstS played a vital role in the secretion system of V. alginolyticus. The pstS-RNAi with the highest silencing efficiency was selected for transcriptome sequencing. The Differentially Expressed Genes (DEGs) and GO terms were mapped to the reference genome of V. alginolyticus, including 1055 up-regulated genes and 1134 down-regulated genes. The functions of the DEGs were analyzed by GO and categorized into different enriched functional groups, such as ribosome synthesis, organelles, biosynthesis, pathogenesis, and secretion. These DEGs were then mapped to the reference KEGG pathways of V. alginolyticus and enriched in commonalities in the metabolic, ribosomal, and bacterial secretion pathways. Therefore, pstS and pstB could regulate the bacterial virulence of V. alginolyticus by affecting its adhesion, biofilm formation ability, and motility. Understanding the relationship between the expressions of pstS and pstB with bacterial virulence could provide new perspectives to prevent bacterial diseases.
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Affiliation(s)
- Xin Yi
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Xiaojin Xu
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Xin Qi
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Yunong Chen
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Zhiqin Zhu
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Genhuang Xu
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Huiyao Li
- Fisheries Research Institute of Fujian, Xiamen 361013, China
| | - Emma-Katharine Kraco
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 East Greenfield Avenue, Milwaukee, WI 53204, USA
| | - Haoyang Shen
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Mao Lin
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Jiang Zheng
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Yingxue Qin
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
| | - Xinglong Jiang
- Key Laboratory of Healthy Mariculture for the East China Sea, Engineering Research Center of the Modern Technology for Eel Industry, Fisheries College, Jimei University, Xiamen 361021, China
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29
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Jacobsen T, Dazzoni R, Renault MG, Bardiaux B, Nilges M, Shevchik V, Izadi-Pruneyre N. Secondary structure and 1H, 15 N & 13C resonance assignments of the periplasmic domain of OutG, major pseudopilin from Dickeya dadantii type II secretion system. BIOMOLECULAR NMR ASSIGNMENTS 2022; 16:231-236. [PMID: 35482172 PMCID: PMC9510105 DOI: 10.1007/s12104-022-10085-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
The ability to interact and adapt to the surrounding environment is vital for bacteria that colonise various niches and organisms. One strategy developed by Gram-negative bacteria is to secrete exoprotein substrates via the type II secretion system (T2SS). The T2SS is a proteinaceous complex spanning the bacterial envelope that translocates folded proteins such as toxins and enzymes from the periplasm to the extracellular milieu. In the T2SS, a cytoplasmic ATPase elongates in the periplasm the pseudopilus, a non-covalent polymer composed of protein subunits named pseudopilins, and anchored in the inner membrane by a transmembrane helix. The pseudopilus polymerisation is coupled to the secretion of substrates. The T2SS of Dickeya dadantii secretes more than 15 substrates, essentially plant cell wall degrading enzymes. In D. dadantii, the major pseudopilin or the major subunit of the pseudopilus is called OutG. To better understand the mechanism of secretion of these numerous substrates via the pseudopilus, we have been studying the structure of OutG by NMR. Here, as the first part of this study, we report the 1H, 15N and 13C backbone and sidechain chemical shift assignment of the periplasmic domain of OutG and its NMR derived secondary structure.
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Affiliation(s)
- Theis Jacobsen
- CNRS UMR3528, Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, 75015, Paris, France
- Sorbonne Université, Complexité du Vivant, 75005, Paris, France
| | - Régine Dazzoni
- CNRS UMR3528, Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Melvin G Renault
- Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, Microbiologie Adaptation et Pathogénie, 69622, Villeurbanne, France
| | - Benjamin Bardiaux
- CNRS UMR3528, Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Michael Nilges
- CNRS UMR3528, Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Vladimir Shevchik
- Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, Microbiologie Adaptation et Pathogénie, 69622, Villeurbanne, France
| | - Nadia Izadi-Pruneyre
- CNRS UMR3528, Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, 75015, Paris, France.
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30
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Suraby EJ, Sruthi KB, Antony G. Genome-wide identification of type III effectors and other virulence factors in Ralstonia pseudosolanacearum causing bacterial wilt in ginger (Zingiber officinale). Mol Genet Genomics 2022; 297:1371-1388. [PMID: 35879566 DOI: 10.1007/s00438-022-01925-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 07/04/2022] [Indexed: 10/16/2022]
Abstract
Ralstonia pseudosolanacearum causes bacterial wilt in ginger, reducing ginger production worldwide. We sequenced the whole genome of a highly virulent phylotype I, race 4, biovar 3 Ralstonia pseudosolanacearum strain GRsMep isolated from a severely infected ginger field in India. R. pseudosolanacearum GRsMep genome is organised into two replicons: chromosome and megaplasmid with a total genome size of 5,810,605 bp. This strain encodes approximately 72 effectors which include a combination of core effectors as well as highly variable, diverse repertoire of type III effectors. Comparative genome analysis with GMI1000 identified conservation in the genes involved in the general virulence mechanism. Our analysis identified type III effectors, RipBJ and RipBO as present in GRsMep but absent in the reported genomes of other strains infecting Zingiberaceae family. GRsMep contains 126 unique genes when compared to the pangenome of the Ralstonia strains that infect the Zingiberaceae family. The whole-genome data of R. pseudosolanacearum strain will serve as a resource for exploring the evolutionary processes that structure and regulate the virulence determinants of the strain. Pathogenicity testing of the transposon insertional mutant library of GRsMep through virulence assay on ginger plants identified a few candidate virulence determinants specific to bacterial wilt in ginger.
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Affiliation(s)
- Erinjery Jose Suraby
- Department of Plant Science, Central University of Kerala, Periye, 671320, Kasaragod, Kerala, India
| | - K Bharathan Sruthi
- Department of Plant Science, Central University of Kerala, Periye, 671320, Kasaragod, Kerala, India
| | - Ginny Antony
- Department of Plant Science, Central University of Kerala, Periye, 671320, Kasaragod, Kerala, India.
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Dade CM, Douzi B, Cambillau C, Ball G, Voulhoux R, Forest KT. The crystal structure of CbpD clarifies substrate-specificity motifs in chitin-active lytic polysaccharide monooxygenases. Acta Crystallogr D Struct Biol 2022; 78:1064-1078. [PMID: 35916229 PMCID: PMC9344471 DOI: 10.1107/s2059798322007033] [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: 04/16/2022] [Accepted: 07/08/2022] [Indexed: 11/23/2022] Open
Abstract
The 3 Å resolution crystal structure of the Pseudomonas aeruginosa virulence factor CbpD both supports and challenges the current model of how lytic polysaccharide monooxygenases bind chitin and raises interesting possibilities about how type 2 secretion-system substrates may interact with the secretion machinery. This structure also demonstrates the utility of new, AI-powered, protein structure-prediction algorithms in making challenging structural targets tractable. Pseudomonas aeruginosa secretes diverse proteins via its type 2 secretion system, including a 39 kDa chitin-binding protein, CbpD. CbpD has recently been shown to be a lytic polysaccharide monooxygenase active on chitin and to contribute substantially to virulence. To date, no structure of this virulence factor has been reported. Its first two domains are homologous to those found in the crystal structure of Vibrio cholerae GbpA, while the third domain is homologous to the NMR structure of the CBM73 domain of Cellvibrio japonicusCjLPMO10A. Here, the 3.0 Å resolution crystal structure of CbpD solved by molecular replacement is reported, which required ab initio models of each CbpD domain generated by the artificial intelligence deep-learning structure-prediction algorithm RoseTTAFold. The structure of CbpD confirms some previously reported substrate-specificity motifs among LPMOAA10s, while challenging the predictive power of others. Additionally, the structure of CbpD shows that post-translational modifications occur on the chitin-binding surface. Moreover, the structure raises interesting possibilities about how type 2 secretion-system substrates may interact with the secretion machinery and demonstrates the utility of new artificial intelligence protein structure-prediction algorithms in making challenging structural targets tractable.
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Kopf A, Bunk B, Coldewey SM, Gunzer F, Riedel T, Schröttner P. Comparative Genomic Analysis of the Human Pathogen Wohlfahrtiimonas Chitiniclastica Provides Insight Into the Identification of Antimicrobial Resistance Genotypes and Potential Virulence Traits. Front Cell Infect Microbiol 2022; 12:912427. [PMID: 35873140 PMCID: PMC9301364 DOI: 10.3389/fcimb.2022.912427] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/02/2022] [Indexed: 11/20/2022] Open
Abstract
Recent studies suggest that Wohlfahrtiimonas chitiniclastica may be the cause of several diseases in humans including sepsis and bacteremia making the bacterium as a previously underappreciated human pathogen. However, very little is known about the pathogenicity and genetic potential of W. chitiniclastica; therefore, it is necessary to conduct systematic studies to gain a deeper understanding of its virulence characteristics and treatment options. In this study, the entire genetic repertoire of all publicly available W. chitiniclastica genomes was examined including in silico characterization of bacteriophage content, antibiotic resistome, and putative virulence profile. The pan-genome of W. chitiniclastica comprises 3819 genes with 1622 core genes (43%) indicating a putative metabolic conserved species. Furthermore, in silico analysis indicated presumed resistome expansion as defined by the presence of genome-encoded transposons and bacteriophages. While macrolide resistance genes macA and macB are located within the core genome, additional antimicrobial resistance genotypes for tetracycline (tetH, tetB, and tetD), aminoglycosides (ant(2’’)-Ia, aac(6’)-Ia,aph(3’’)-Ib, aph(3’)-Ia, and aph(6)-Id)), sulfonamide (sul2), streptomycin (strA), chloramphenicol (cat3), and beta-lactamase (blaVEB) are distributed among the accessory genome. Notably, our data indicate that the type strain DSM 18708T does not encode any additional clinically relevant antibiotic resistance genes, whereas drug resistance is increasing within the W. chitiniclastica clade. This trend should be monitored with caution. To the best of our knowledge, this is the first comprehensive genome analysis of this species, providing new insights into the genome of this opportunistic human pathogen.
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Affiliation(s)
- Anna Kopf
- Medical Microbiology and Virology, University Hospital Carl Gustav Carus, Dresden, Germany
- Clinic for Hematology and Oncology, Carl-Thiem-Klinikum, Cottbus, Germany
| | - Boyke Bunk
- German Collection of Microorganisms and Cell Cultures GmbH, Leibniz Institute DSMZ, Braunschweig, Germany
| | - Sina M. Coldewey
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany
- Septomics Research Center, Jena University Hospital, Jena, Germany
| | - Florian Gunzer
- Department of Hospital Infection Control, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Thomas Riedel
- German Collection of Microorganisms and Cell Cultures GmbH, Leibniz Institute DSMZ, Braunschweig, Germany
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Braunschweig, Germany
| | - Percy Schröttner
- Medical Microbiology and Virology, University Hospital Carl Gustav Carus, Dresden, Germany
- *Correspondence: Percy Schröttner,
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Guo M, Tan S, Zhu J, Sun A, Du P, Liu X. Genes Involved in Biofilm Matrix Formation of the Food Spoiler Pseudomonas fluorescens PF07. Front Microbiol 2022; 13:881043. [PMID: 35733961 PMCID: PMC9207406 DOI: 10.3389/fmicb.2022.881043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
The extracellular matrix is essential for the biofilm formation of food spoilers. Pseudomonas fluorescens PF07 is a previous isolate from spoiled marine fish; however, the genes involved in the extracellular matrix formation of PF07 biofilms remain poorly defined. In this study, PF07 formed a wrinkled macrocolony biofilm through the high production of extracellular matrix. The genes involved in biofilm matrix formation and regulation were screened and identified by RNA-seq-dependent transcriptomic analysis and gene knock-out analysis. The macrocolony biofilms of PF07 grown for 5 days (PF07_5d) were compared with those grown for 1 day (PF07_1d). A total of 1,403 genes were significantly differentially expressed during biofilm formation. These mainly include the genes related to biofilm matrix proteins, polysaccharides, rhamnolipids, secretion system, biofilm regulation, and metabolism. Among them, functional amyloid genes fapABCDE were highly upregulated in the mature biofilm, and the operon fapA-E had a –24/–12 promoter dependent on the sigma factor RpoN. Moreover, the RNA-seq analyses of the rpoN mutant, compared with PF07, revealed 159 genes were differentially expressed in the macrocolony biofilms, and fapA-E genes were positively regulated by RpoN. In addition, the deletion mutants of fapC, rpoN, and brfA (a novel gene coding for an RpoN-dependent transcriptional regulator) were defective in forming mature macrocolony biofilms, solid surface-associated (SSA) biofilms, and pellicles, and they showed significantly reduced biofilm matrices. The fap genes were significantly downregulated in ΔbrfA, as in ΔrpoN. These findings suggest that the functional amyloid Fap is the main component of PF07 biofilm matrices, and RpoN may directly regulate the transcription of fap genes, in conjunction with BrfA. These genes may serve as potential molecular targets for screening new anti-biofilm agents or for biofilm detection in food environments.
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Affiliation(s)
- Miao Guo
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China
- School of Public Health, Hangzhou Medical College, Hangzhou, China
| | - Siqi Tan
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China
- School of Public Health, Hangzhou Medical College, Hangzhou, China
| | - Junli Zhu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Aihua Sun
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China
| | - Peng Du
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China
| | - Xiaoxiang Liu
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China
- *Correspondence: Xiaoxiang Liu,
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Scaffolding Protein GspB/OutB Facilitates Assembly of the Dickeya dadantii Type 2 Secretion System by Anchoring the Outer Membrane Secretin Pore to the Inner Membrane and to the Peptidoglycan Cell Wall. mBio 2022; 13:e0025322. [PMID: 35546537 PMCID: PMC9239104 DOI: 10.1128/mbio.00253-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The phytopathogenic proteobacterium Dickeya dadantii secretes an array of plant cell wall-degrading enzymes and other virulence factors via the type 2 secretion system (T2SS). T2SSs are widespread among important plant, animal, and human bacterial pathogens. This multiprotein complex spans the double membrane cell envelope and secretes fully folded proteins through a large outer membrane pore formed by 15 subunits of the secretin GspD. Secretins are also found in the type 3 secretion system and the type 4 pili. Usually, specialized lipoproteins termed pilotins assist the targeting and assembly of secretins into the outer membrane. Here, we show that in D. dadantii, the pilotin acts in concert with the scaffolding protein GspB. Deletion of gspB profoundly impacts secretin assembly, pectinase secretion, and virulence. Structural studies reveal that GspB possesses a conserved periplasmic homology region domain that interacts directly with the N-terminal secretin domain. Site-specific photo-cross-linking unravels molecular details of the GspB-GspD complex in vivo. We show that GspB facilitates outer membrane targeting and assembly of the secretin pores and anchors them to the inner membrane while the C-terminal extension of GspB provides a scaffold for the secretin channel in the peptidoglycan cell wall. Phylogenetic analysis shows that in other bacteria, GspB homologs vary in length and domain composition and act in concert with either a cognate ATPase GspA or the pilotin GspS.
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Rosenberg T, Jiménez-Guerrero I, Tamir-Ariel D, Yarnitzky T, Burdman S. The GDSL-Lipolytic Enzyme Lip1 Is Required for Full Virulence of the Cucurbit Pathogenic Bacterium Acidovorax citrulli. Microorganisms 2022; 10:microorganisms10051016. [PMID: 35630458 PMCID: PMC9147443 DOI: 10.3390/microorganisms10051016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/04/2022] [Accepted: 05/09/2022] [Indexed: 02/01/2023] Open
Abstract
Bacterial fruit blotch caused by Acidovoraxcitrulli is a serious disease of cucurbit crops. Here we report characterization of a mutant strain of A. citrulli M6 defective in lip1, a gene encoding a lipolytic enzyme. The M6-lip1- mutant was detected in a mutant library screen aimed at identifying M6 mutants with altered levels of twitching motility. In this screen M6-lip1- was the only mutant that showed significantly larger twitching motility haloes around colonies than wild-type M6. Sequence analyses indicated that lip1 encodes a member of the GDSL family of secreted lipolytic enzymes. In line with this finding, lipolytic assays showed that the supernatants of M6-lip1- had lower lipolytic activity as compared with those of wild-type M6 and a lip1-complemented strain. The mutant was also affected in swimming motility and had compromised virulence on melon seedlings and on Nicotiana benthamiana leaves relative to wild-type and complemented strains. Lip1 contains a predicted N-terminal signal sequence for type II secretion. Evidence from our study confirms Lip1 is indeed secreted in a type II secretion-dependent manner, and this is required for full virulence of A. citrulli. To the best of our knowledge this is the first study reporting contribution of lipolytic activity to virulence of a plant-pathogenic Acidovorax species.
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Affiliation(s)
- Tally Rosenberg
- Department of Plant Pathology and Microbiology, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (T.R.); (I.J.-G.); (D.T.-A.); (T.Y.)
| | - Irene Jiménez-Guerrero
- Department of Plant Pathology and Microbiology, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (T.R.); (I.J.-G.); (D.T.-A.); (T.Y.)
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, 41012 Sevilla, Spain
| | - Dafna Tamir-Ariel
- Department of Plant Pathology and Microbiology, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (T.R.); (I.J.-G.); (D.T.-A.); (T.Y.)
| | - Tali Yarnitzky
- Department of Plant Pathology and Microbiology, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (T.R.); (I.J.-G.); (D.T.-A.); (T.Y.)
| | - Saul Burdman
- Department of Plant Pathology and Microbiology, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (T.R.); (I.J.-G.); (D.T.-A.); (T.Y.)
- Correspondence: ; Tel.: +972-8-9489369
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Martínez OF, Duque HM, Franco OL. Peptidomimetics as Potential Anti-Virulence Drugs Against Resistant Bacterial Pathogens. Front Microbiol 2022; 13:831037. [PMID: 35516442 PMCID: PMC9062693 DOI: 10.3389/fmicb.2022.831037] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/28/2022] [Indexed: 12/11/2022] Open
Abstract
The uncontrollable spread of superbugs calls for new approaches in dealing with microbial-antibiotic resistance. Accordingly, the anti-virulence approach has arisen as an attractive unconventional strategy to face multidrug-resistant pathogens. As an emergent strategy, there is an imperative demand for discovery, design, and development of anti-virulence drugs. In this regard, peptidomimetic compounds could be a valuable source of anti-virulence drugs, since these molecules circumvent several shortcomings of natural peptide-based drugs like proteolytic instability, immunogenicity, toxicity, and low bioavailability. Some emerging evidence points to the feasibility of peptidomimetics to impair pathogen virulence. Consequently, in this review, we shed some light on the potential of peptidomimetics as anti-virulence drugs to overcome antibiotic resistance. Specifically, we address the anti-virulence activity of peptidomimetics against pathogens' secretion systems, biofilms, and quorum-sensing systems.
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Affiliation(s)
- Osmel Fleitas Martínez
- Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil.,Programa de Pós-Graduação em Biotecnologia, S-Inova Biotech, Universidade Católica Dom Bosco, Campo Grande, Brazil
| | - Harry Morales Duque
- Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil
| | - Octávio Luiz Franco
- Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil.,Programa de Pós-Graduação em Biotecnologia, S-Inova Biotech, Universidade Católica Dom Bosco, Campo Grande, Brazil
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Basu S, Huynh L, Zhang S, Rabara R, Nguyen H, Velásquez Guzmán J, Hao G, Miles G, Shi Q, Stover E, Gupta G. Two Liberibacter Proteins Combine to Suppress Critical Innate Immune Defenses in Citrus. FRONTIERS IN PLANT SCIENCE 2022; 13:869178. [PMID: 35586217 PMCID: PMC9108871 DOI: 10.3389/fpls.2022.869178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/04/2022] [Indexed: 06/15/2023]
Abstract
We adopted a systems-based approach to determine the role of two Candidatus Liberibacter asiaticus (CLas) proteins, LasP 235 and Effector 3, in Huanglongbing (HLB) pathogenesis. While a published work suggests the involvement of these CLas proteins HLB pathogenesis, the exact structure-based mechanism of their action has not been elucidated. We conducted the following experiments to determine the structure-based mechanisms of action. First, we immunoprecipitated the interacting citrus protein partners of LasP 235 and Effector 3 from the healthy and CLas-infected Hamlin extracts and identified them by Liquid Chromatography with tandem mass spectrometry (LC-MS/MS). Second, we performed a split green fluorescent protein (GFP) assay in tobacco to validate that the interactions observed in vitro are also retained in planta. The notable in planta citrus targets of LasP 235 and Effector 3 include citrus innate immune proteins. Third, in vitro and in planta studies were performed to show that LasP 235 and Effector 3 interact with and inhibit the functions of multiple citrus proteins belonging to the innate immune pathways. These inhibitory interactions led to a high level of reactive oxygen species, blocking of bactericidal lipid transfer protein (LTP), and induction of premature programed cell death (PCD), all of which are beneficial to CLas lifecycle and HLB pathogenesis. Finally, we performed molecular dynamics simulations to visualize the interactions of LasP 235 and Effector 3, respectively, with LTP and Kunitz protease inhibitor. This led to the design of an LTP mimic, which sequestered and blocked LasP 235 and rescued the bactericidal activity of LTP thereby proving that LasP 235 , indeed, participates in HLB pathogenesis.
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Affiliation(s)
- Supratim Basu
- Biolab, New Mexico Consortium, Los Alamos, NM, United States
| | - Loan Huynh
- Biolab, New Mexico Consortium, Los Alamos, NM, United States
| | - Shujian Zhang
- Biolab, New Mexico Consortium, Los Alamos, NM, United States
| | - Roel Rabara
- Biolab, New Mexico Consortium, Los Alamos, NM, United States
| | - Hau Nguyen
- Biolab, New Mexico Consortium, Los Alamos, NM, United States
| | | | - Guixia Hao
- Horticulture and Breeding, U. S. Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Godfrey Miles
- Horticulture and Breeding, U. S. Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Qingchun Shi
- Horticulture and Breeding, U. S. Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Ed Stover
- Horticulture and Breeding, U. S. Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Goutam Gupta
- Biolab, New Mexico Consortium, Los Alamos, NM, United States
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Mekasha S, Linke D. Secretion Systems in Gram-Negative Bacterial Fish Pathogens. Front Microbiol 2022; 12:782673. [PMID: 34975803 PMCID: PMC8714846 DOI: 10.3389/fmicb.2021.782673] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/24/2021] [Indexed: 12/17/2022] Open
Abstract
Bacterial fish pathogens are one of the key challenges in the aquaculture industry, one of the fast-growing industries worldwide. These pathogens rely on arsenal of virulence factors such as toxins, adhesins, effectors and enzymes to promote colonization and infection. Translocation of virulence factors across the membrane to either the extracellular environment or directly into the host cells is performed by single or multiple dedicated secretion systems. These secretion systems are often key to the infection process. They can range from simple single-protein systems to complex injection needles made from dozens of subunits. Here, we review the different types of secretion systems in Gram-negative bacterial fish pathogens and describe their putative roles in pathogenicity. We find that the available information is fragmented and often descriptive, and hope that our overview will help researchers to more systematically learn from the similarities and differences between the virulence factors and secretion systems of the fish-pathogenic species described here.
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Affiliation(s)
- Sophanit Mekasha
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
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Zárate‐Chaves CA, Gómez de la Cruz D, Verdier V, López CE, Bernal A, Szurek B. Cassava diseases caused by Xanthomonas phaseoli pv. manihotis and Xanthomonas cassavae. MOLECULAR PLANT PATHOLOGY 2021; 22:1520-1537. [PMID: 34227737 PMCID: PMC8578842 DOI: 10.1111/mpp.13094] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 05/04/2021] [Accepted: 05/04/2021] [Indexed: 05/27/2023]
Abstract
Xanthomonas phaseoli pv. manihotis (Xpm) and X. cassavae (Xc) are two bacterial pathogens attacking cassava. Cassava bacterial blight (CBB) is a systemic disease caused by Xpm, which might have dramatic effects on plant growth and crop production. Cassava bacterial necrosis is a nonvascular disease caused by Xc with foliar symptoms similar to CBB, but its impacts on the plant vigour and the crop are limited. In this review, we describe the epidemiology and ecology of the two pathogens, the impacts and management of the diseases, and the main research achievements for each pathosystem. Because Xc data are sparse, our main focus is on Xpm and CBB.
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Affiliation(s)
| | | | - Valérie Verdier
- PHIMUniversité MontpellierCIRADINRAeIRDInstitut AgroMontpellierFrance
| | - Camilo E. López
- Manihot Biotec, Departamento de BiologíaUniversidad Nacional de ColombiaBogotáColombia
| | - Adriana Bernal
- Laboratorio de Interacciones Moleculares de Microorganismos AgrícolasDepartamento de Ciencias BásicasUniversidad de los AndesBogotáColombia
| | - Boris Szurek
- PHIMUniversité MontpellierCIRADINRAeIRDInstitut AgroMontpellierFrance
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Motor-independent retraction of type IV pili is governed by an inherent property of the pilus filament. Proc Natl Acad Sci U S A 2021; 118:2102780118. [PMID: 34789573 DOI: 10.1073/pnas.2102780118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2021] [Indexed: 12/21/2022] Open
Abstract
Type IV pili (T4P) are dynamic surface appendages that promote virulence, biofilm formation, horizontal gene transfer, and motility in diverse bacterial species. Pilus dynamic activity is best characterized in T4P that use distinct ATPase motors for pilus extension and retraction. Many T4P systems, however, lack a dedicated retraction motor, and the mechanism underlying this motor-independent retraction remains a mystery. Using the Vibrio cholerae competence pilus as a model system, we identify mutations in the major pilin gene that enhance motor-independent retraction. These mutants likely diminish pilin-pilin interactions within the filament to produce less-stable pili. One mutation adds a bulky residue to α1C, a universally conserved feature of T4P. We found that inserting a bulky residue into α1C of the retraction motor-dependent Acinetobacter baylyi competence T4P enhances motor-independent retraction. Conversely, removing bulky residues from α1C of the retraction motor-independent, V. cholerae toxin-coregulated T4P stabilizes the filament and diminishes pilus retraction. Furthermore, alignment of pilins from the broader type IV filament (T4F) family indicated that retraction motor-independent T4P, gram-positive Com pili, and type II secretion systems generally encode larger residues within α1C oriented toward the pilus core compared to retraction motor-dependent T4P. Together, our data demonstrate that motor-independent retraction relies, in part, on the inherent instability of the pilus filament, which may be a conserved feature of diverse T4Fs. This provides evidence for a long-standing yet previously untested model in which pili retract in the absence of a motor by spontaneous depolymerization.
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Hu M, Li C, Xue Y, Hu A, Chen S, Chen Y, Lu G, Zhou X, Zhou J. Isolation, Characterization, and Genomic Investigation of a Phytopathogenic Strain of Stenotrophomonas maltophilia. PHYTOPATHOLOGY 2021; 111:2088-2099. [PMID: 33759550 DOI: 10.1094/phyto-11-20-0501-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Stenotrophomonas maltophilia is ubiquitous in diverse environmental habitats. It merits significant concern because of its increasing incidence of nosocomial and community-acquired infection in immunocompromised patients and multiple drug resistance. It is rarely reported as a phytopathogen except in causing white stripe disease of rice in India and postharvest fruit rot of Lanzhou lily. For this study, Dickeya zeae and S. maltophilia strains were simultaneously isolated from soft rot leaves of Clivia miniata in Guangzhou, China, and were both demonstrated to be pathogenic to the host. Compared with the D. zeae strains, S. maltophilia strains propagated faster for greater growth in lysogeny broth medium and produced no cellulases or polygalacturonases, but did produce more proteases and fewer extracellular polysaccharides. Furthermore, S. maltophilia strains swam and swarmed dramatically less on semisolid media, but formed a great many more biofilms. Both D. zeae and S. maltophilia strains isolated from clivia caused rot symptoms on other monocot hosts, but not on dicots. Similar to previously reported S. maltophilia strains isolated from other sources, the strain JZL8 survived under many antibiotic stresses. The complete genome sequence of S. maltophilia strain JZL8 consists of a chromosome of 4,635,432 bp without a plasmid. Pan-genome analysis of JZL8 and 180 other S. maltophilia strains identified 50 genes that are unique to JZL8, seven of which implicate JZL8 as the potential pathogen contributor in plants. JZL8 also contains three copies of Type I Secretion System machinery; this is likely responsible for its greater production of proteases. Findings from this study extend our knowledge on the host range of S. maltophilia and provide insight into the phenotypic and genetic features underlying the plant pathogenicity of JZL8.
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Affiliation(s)
- Ming Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Chuhao Li
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Yang Xue
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Anqun Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Shanshan Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Yufan Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Guangtao Lu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China
| | - Xiaofan Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Jianuan Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
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Budowa i znaczenie II systemu sekrecji białek w ekologii i patogenezie Legionella pneumophila. POSTEP HIG MED DOSW 2021. [DOI: 10.2478/ahem-2021-0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Pałeczki Legionella pneumophila pasożytują w komórkach odległych filogenetycznie gospodarzy, w środowisku wodnym w pierwotniakach, a w organizmie człowieka w makrofagach alweolarnych. Zdolność tych bakterii do wewnątrzkomórkowego namnażania się w komórkach fagocytujących, wyspecjalizowanych do niszczenia mikroorganizmów, ma podstawowe znaczenie dla rozwoju nietypowego zapalenia płuc zwanego chorobą legionistów. Umiejscowione na kilku różnych loci chromosomu bakteryjnego geny II systemu sekrecji L. pneumophila kodują co najmniej 25 białek, w tym enzymy o aktywności lipolitycznej, proteolitycznej, rybonukleazy oraz białka unikalne bakterii Legionella. W środowisku naturalnym T2SS L. pneumophila odgrywa decydującą rolę w ekologii tych drobnoustrojów determinując ich zdolność do przeżycia zarówno w postaci planktonicznej, jak i w strukturach biofilmu w słodkowodnych zbiornikach o niskiej temperaturze. Białka T2SS umożliwiają L. pneumophila zakażenie różnych gatunków pierwotniaków, a substraty tego systemu określają zakres pierwotniaczego gospodarza. Namnażanie się bakterii w różnorodnych pierwotniakach przyczynia się do ich rozsiewania oraz transmisji do antropogenicznych źródeł. Białka wydzielane za pomocą II systemu sekrecji determinują również zdolność L. pneumophila do zakażania mysich makrofagów alweolarnych i szpiku kostnego, ludzkich makrofagów linii U937 i THP-1 oraz komórek nabłonkowych pęcherzyków płucnych. Enzymy wydzielane za pomocą tego systemu, takie jak: proteazy, aminopeptydazy czy fosfolipazy umożliwiają pozyskanie substancji pokarmowych oraz powodują destrukcję tkanki płucnej myszy. W organizmie człowieka białka T2SS przyczyniają się do osłabienia wrodzonej odpowiedzi immunologicznej na zakażenie L. pneumophila przez hamowanie indukcji prozapalnych cytokin (IL-6, TNF-α, IL-1 oraz IL-8).
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Colombi E, Perry BJ, Sullivan JT, Bekuma AA, Terpolilli JJ, Ronson CW, Ramsay JP. Comparative analysis of integrative and conjugative mobile genetic elements in the genus Mesorhizobium. Microb Genom 2021; 7. [PMID: 34605762 PMCID: PMC8627217 DOI: 10.1099/mgen.0.000657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Members of the Mesorhizobium genus are soil bacteria that often form nitrogen-fixing symbioses with legumes. Most characterised Mesorhizobium spp. genomes are ~8 Mb in size and harbour extensive pangenomes including large integrative and conjugative elements (ICEs) carrying genes required for symbiosis (ICESyms). Here, we document and compare the conjugative mobilome of 41 complete Mesorhizobium genomes. We delineated 56 ICEs and 24 integrative and mobilizable elements (IMEs) collectively occupying 16 distinct integration sites, along with 24 plasmids. We also demonstrated horizontal transfer of the largest (853,775 bp) documented ICE, the tripartite ICEMspSymAA22. The conjugation systems of all identified ICEs and several plasmids were related to those of the paradigm ICESym ICEMlSymR7A, with each carrying conserved genes for conjugative pilus formation (trb), excision (rdfS), DNA transfer (rlxS) and regulation (fseA). ICESyms have likely evolved from a common ancestor, despite occupying a variety of distinct integration sites and specifying symbiosis with diverse legumes. We found extensive evidence for recombination between ICEs and particularly ICESyms, which all uniquely lack the conjugation entry-exclusion factor gene trbK. Frequent duplication, replacement and pseudogenization of genes for quorum-sensing-mediated activation and antiactivation of ICE transfer suggests ICE transfer regulation is constantly evolving. Pangenome-wide association analysis of the ICE identified genes potentially involved in symbiosis, rhizosphere colonisation and/or adaptation to distinct legume hosts. In summary, the Mesorhizobium genus has accumulated a large and dynamic pangenome that evolves through ongoing horizontal gene transfer of large conjugative elements related to ICEMlSymR7A.
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Affiliation(s)
- Elena Colombi
- Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia.,Curtin Medical School, Curtin University, Perth, WA, Australia
| | - Benjamin J Perry
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - John T Sullivan
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Amanuel A Bekuma
- Centre for Rhizobium Studies, Food Futures Institute, Murdoch University, Perth, WA, Australia, Murdoch University, Perth, WA, Australia.,Present address: Western Australian Department of Primary Industries and Regional Development, Research and Industry Innovation, South Perth, WA, Australia
| | - Jason J Terpolilli
- Centre for Rhizobium Studies, Food Futures Institute, Murdoch University, Perth, WA, Australia, Murdoch University, Perth, WA, Australia
| | - Clive W Ronson
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Joshua P Ramsay
- Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia.,Curtin Medical School, Curtin University, Perth, WA, Australia
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Dazzoni R, López-Castilla A, Cordier F, Bardiaux B, Nilges M, Francetic O, Izadi-Pruneyre N. 1H, 15 N and 13C resonance assignments of the C-terminal domain of PulL, a component of the Klebsiella oxytoca type II secretion system. BIOMOLECULAR NMR ASSIGNMENTS 2021; 15:455-459. [PMID: 34410621 DOI: 10.1007/s12104-021-10045-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
Type II secretion systems (T2SS) allow Gram-negative bacteria to transport toxins and enzymes from the periplasm to the external milieu, and are thus important for the pathogenicity of bacteria. To drive secretion, T2SS assemble filaments called pseudopili closely related to bacterial type IV pili. These filaments are non-covalent polymers of proteins that are assembled by an inner membrane complex called the assembly platform connected to a cytoplasmic ATPase motor. In the Klebsiella oxytoca T2SS, the PulL protein from the assembly platform is essential for pseudopilus assembly and protein secretion. However, its role in these processes is not well understood. To decipher the molecular basis of PulL function, we used solution NMR to study its structure and interactions with other components of the machinery. Here as a first step, we report the 1H, 15 N and 13C backbone and side-chain chemical shift assignments of the C-terminal periplasmic domain of PulL and its secondary structure based on NMR data.
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Affiliation(s)
- Régine Dazzoni
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Aracelys López-Castilla
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Florence Cordier
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
- Biological NMR Technological Platform, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France.
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Rai R, Pasion J, Majumdar T, Green CE, Hind SR. Genome Sequencing and Functional Characterization of Xanthomonas cucurbitae, the Causal Agent of Bacterial Spot Disease of Cucurbits. PHYTOPATHOLOGY 2021; 111:1289-1300. [PMID: 33734871 DOI: 10.1094/phyto-06-20-0228-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bacterial leaf spot disease caused by Xanthomonas cucurbitae has severely affected the pumpkin industries in the Midwestern region of United States, with the bacteria mainly infecting pumpkin leaves and fruits, and leading to significant yield losses. In this study, we utilized genomics and genetics approaches to elucidate X. cucurbitae molecular mechanisms of pathogenesis during interaction with its host. We generated the first reference-quality whole-genome sequence of the X. cucurbitae type isolate and compared with other Xanthomonas species, X. cucurbitae has a smaller genome size with fewer virulence-related genes. RNA-seq analysis of X. cucurbitae under plant-mimicking media conditions showed altered transcriptional responses, with upregulation of virulence genes and downregulation of cellular homeostasis genes. Additionally, characterization of key virulence genes using gene deletion methods revealed that both type II enzymes and type III effectors are necessary for X. cucurbitae to cause infection in the pumpkin host.
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Affiliation(s)
- Rikky Rai
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Julius Pasion
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Tanvi Majumdar
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Cory E Green
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Sarah R Hind
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
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Redfern J, Wallace J, van Belkum A, Jaillard M, Whittard E, Ragupathy R, Verran J, Kelly P, Enright MC. Biofilm associated genotypes of multiple antibiotic resistant Pseudomonas aeruginosa. BMC Genomics 2021; 22:572. [PMID: 34311706 PMCID: PMC8314537 DOI: 10.1186/s12864-021-07818-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 06/14/2021] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Pseudomonas aeruginosa is a ubiquitous environmental microorganism and also a common cause of infection. Its ability to survive in many different environments and persistently colonize humans is linked to its presence in biofilms formed on indwelling device surfaces. Biofilm promotes adhesion to, and survival on surfaces, protects from desiccation and the actions of antibiotics and disinfectants. RESULTS We examined the genetic basis for biofilm production on polystyrene at room (22 °C) and body temperature (37 °C) within 280 P. aeruginosa. 193 isolates (69 %) produced more biofilm at 22 °C than at 37 °C. Using GWAS and pan-GWAS, we found a number of accessory genes significantly associated with greater biofilm production at 22 °C. Many of these are present on a 165 kb region containing genes for heavy metal resistance (arsenic, copper, mercury and cadmium), transcriptional regulators and methytransferases. We also discovered multiple core genome SNPs in the A-type flagellin gene and Type II secretion system gene xpsD. Analysis of biofilm production of isolates of the MDR ST111 and ST235 lineages on stainless-steel revealed several accessory genes associated with enhanced biofilm production. These include a putative translocase with homology to a Helicobacter pylori type IV secretion system protein, a TA system II toxin gene and the alginate biosynthesis gene algA, several transcriptional regulators and methytransferases as well as core SNPs in genes involved in quorum sensing and protein translocation. CONCLUSIONS Using genetic association approaches we discovered a number of accessory genes and core-genome SNPs that were associated with enhanced early biofilm formation at 22 °C compared to 37 °C. These included a 165 kb genomic island containing multiple heavy metal resistance genes, transcriptional regulators and methyltransferases. We hypothesize that this genomic island may be associated with overall genotypes that are environmentally adapted to survive at lower temperatures. Further work to examine their importance in, for example gene-knockout studies, are required to confirm their relevance. GWAS and pan-GWAS approaches have great potential as a first step in examining the genetic basis of novel bacterial phenotypes.
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Affiliation(s)
- James Redfern
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom
| | - Janine Wallace
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom
| | | | | | - Elliot Whittard
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom
| | - Roobinidevi Ragupathy
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom
| | - Joanna Verran
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom
| | - Peter Kelly
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom
| | - Mark Charles Enright
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, United Kingdom.
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Lin Y, Liao YY, Huang RX, Li AZ, An SQ, Tang JL, Tang DJ. Extracellular Amylase Is Required for Full Virulence and Regulated by the Global Posttranscriptional Regulator RsmA in Xanthomonas campestris Pathovar campestris. PHYTOPATHOLOGY 2021; 111:1104-1113. [PMID: 33245253 DOI: 10.1094/phyto-08-20-0372-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As with many phytopathogenic bacteria, the virulence of Xanthomonas campestris pv. campestris, the causal agent of black rot disease in cruciferous plants, relies on secretion of a suite of extracellular enzymes that includes cellulase (endoglucanase), pectinase, protease, and amylase. Although the role in virulence of a number of these enzymes has been assessed, the contribution of amylase to X. campestris pv. campestris virulence has yet to be established. In this work, we investigated both the role of extracellular amylase in X. campestris pv. campestris virulence and the control of its expression. Deletion of XC3487 (here renamed amyAXcc), a putative amylase-encoding gene from the genome of X. campestris pv. campestris strain 8004, resulted in a complete loss of extracellular amylase activity and significant reduction in virulence. The extracellular amylase activity and virulence of the amyAXcc mutant could be restored to the wild-type level by expressing amyAXcc in trans. These results demonstrated that amyAXcc is responsible for the extracellular amylase activity of X. campestris pv. campestris and indicated that extracellular amylase plays an important role in X. campestris pv. campestris virulence. We also found that the expression of amyAXcc is strongly induced by starch and requires activation by the global posttranscriptional regulator RsmA. RsmA binds specifically to the 5'-untranslated region of amyAXcc transcripts, suggesting that RsmA regulates amyAXcc directly at the posttranscriptional level. Unexpectedly, in addition to posttranscriptional regulation, the use of a transcriptional reporter demonstrated that RsmA also regulates amyAXcc expression at the transcriptional level, possibly by an indirect mechanism.
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Affiliation(s)
- Yan Lin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Yong-Yan Liao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Ru-Xia Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Ai-Zhou Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Shi-Qi An
- National Biofilms Innovation Centre, Biological Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Dong-Jie Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
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Sweet M, Villela H, Keller-Costa T, Costa R, Romano S, Bourne DG, Cárdenas A, Huggett MJ, Kerwin AH, Kuek F, Medina M, Meyer JL, Müller M, Pollock FJ, Rappé MS, Sere M, Sharp KH, Voolstra CR, Zaccardi N, Ziegler M, Peixoto R. Insights into the Cultured Bacterial Fraction of Corals. mSystems 2021; 6:e0124920. [PMID: 34156291 PMCID: PMC8269258 DOI: 10.1128/msystems.01249-20] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 05/13/2021] [Indexed: 02/06/2023] Open
Abstract
Bacteria associated with coral hosts are diverse and abundant, with recent studies suggesting involvement of these symbionts in host resilience to anthropogenic stress. Despite their putative importance, the work dedicated to culturing coral-associated bacteria has received little attention. Combining published and unpublished data, here we report a comprehensive overview of the diversity and function of culturable bacteria isolated from corals originating from tropical, temperate, and cold-water habitats. A total of 3,055 isolates from 52 studies were considered by our metasurvey. Of these, 1,045 had full-length 16S rRNA gene sequences, spanning 138 formally described and 12 putatively novel bacterial genera across the Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria phyla. We performed comparative genomic analysis using the available genomes of 74 strains and identified potential signatures of beneficial bacterium-coral symbioses among the strains. Our analysis revealed >400 biosynthetic gene clusters that underlie the biosynthesis of antioxidant, antimicrobial, cytotoxic, and other secondary metabolites. Moreover, we uncovered genomic features-not previously described for coral-bacterium symbioses-potentially involved in host colonization and host-symbiont recognition, antiviral defense mechanisms, and/or integrated metabolic interactions, which we suggest as novel targets for the screening of coral probiotics. Our results highlight the importance of bacterial cultures to elucidate coral holobiont functioning and guide the selection of probiotic candidates to promote coral resilience and improve holistic and customized reef restoration and rehabilitation efforts. IMPORTANCE Our paper is the first study to synthesize currently available but decentralized data of cultured microbes associated with corals. We were able to collate 3,055 isolates across a number of published studies and unpublished collections from various laboratories and researchers around the world. This equated to 1,045 individual isolates which had full-length 16S rRNA gene sequences, after filtering of the original 3,055. We also explored which of these had genomes available. Originally, only 36 were available, and as part of this study, we added a further 38-equating to 74 in total. From this, we investigated potential genetic signatures that may facilitate a host-associated lifestyle. Further, such a resource is an important step in the selection of probiotic candidates, which are being investigated for promoting coral resilience and potentially applied as a novel strategy in reef restoration and rehabilitation efforts. In the spirit of open access, we have ensured this collection is available to the wider research community through the web site http://isolates.reefgenomics.org/ with the hope many scientists across the globe will ask for access to these cultures for future studies.
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Affiliation(s)
- Michael Sweet
- Aquatic Research Facility, Environmental Sustainability Research Centre, University of Derby, Derby, United Kingdom
| | - Helena Villela
- Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Tina Keller-Costa
- Institute for Bioengineering and Biosciences (iBB), University of Lisbon, Lisbon, Portugal
- Instituto Superior Técnico (IST), University of Lisbon, Lisbon, Portugal
| | - Rodrigo Costa
- Institute for Bioengineering and Biosciences (iBB), University of Lisbon, Lisbon, Portugal
- Instituto Superior Técnico (IST), University of Lisbon, Lisbon, Portugal
- Department of Energy, Joint Genome Institute and Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Stefano Romano
- Gut Microbes and Health, Quadram Institute Bioscience, Norwich, United Kingdom
| | - David G. Bourne
- College of Science and Engineering, James Cook University, Townsville, Australia
- Australian Institute of Marine Science, Townsville, Australia
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Megan J. Huggett
- School of Environmental and Life Sciences, The University of Newcastle, Ourimbah, NSW, Australia
- Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA, Australia
| | | | - Felicity Kuek
- Australian Institute of Marine Science, Townsville, Australia
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
| | - Mónica Medina
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Julie L. Meyer
- Soil and Water Sciences Department, Genetics Institute, University of Florida, Gainesville, Florida, USA
| | - Moritz Müller
- Faculty of Engineering, Computing and Science, Swinburne University of Technology Sarawak Campus, Kuching, Sarawak, Malaysia
| | - F. Joseph Pollock
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, USA
- Hawaii and Palmyra Programs, The Nature Conservancy, Honolulu, Hawaii, USA
| | - Michael S. Rappé
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii, USA
| | - Mathieu Sere
- Aquatic Research Facility, Environmental Sustainability Research Centre, University of Derby, Derby, United Kingdom
| | - Koty H. Sharp
- Department of Biology and Marine Biology, Roger Williams University, Bristol, Rhode Island, USA
| | | | - Nathan Zaccardi
- Department of Biology and Marine Biology, Roger Williams University, Bristol, Rhode Island, USA
| | - Maren Ziegler
- Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, Germany
| | - Raquel Peixoto
- Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Red Sea Research Center (RSRC), Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
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Swietnicki W. Secretory System Components as Potential Prophylactic Targets for Bacterial Pathogens. Biomolecules 2021; 11:892. [PMID: 34203937 PMCID: PMC8232601 DOI: 10.3390/biom11060892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 01/18/2023] Open
Abstract
Bacterial secretory systems are essential for virulence in human pathogens. The systems have become a target of alternative antibacterial strategies based on small molecules and antibodies. Strategies to use components of the systems to design prophylactics have been less publicized despite vaccines being the preferred solution to dealing with bacterial infections. In the current review, strategies to design vaccines against selected pathogens are presented and connected to the biology of the system. The examples are given for Y. pestis, S. enterica, B. anthracis, S. flexneri, and other human pathogens, and discussed in terms of effectiveness and long-term protection.
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Affiliation(s)
- Wieslaw Swietnicki
- Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, 53-114 Wroclaw, Poland
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Structural interactions define assembly adapter function of a type II secretion system pseudopilin. Structure 2021; 29:1116-1127.e8. [PMID: 34139172 DOI: 10.1016/j.str.2021.05.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/15/2021] [Accepted: 05/28/2021] [Indexed: 01/13/2023]
Abstract
The type IV filament superfamily comprises widespread membrane-associated polymers in prokaryotes. The type II secretion system (T2SS), a virulence pathway in many pathogens, belongs to this superfamily. A knowledge gap in understanding of the T2SS is the molecular role of a small "pseudopilin" protein. Using multiple biophysical techniques, we have deciphered how this missing component of the Xcp T2SS architecture is structurally integrated, and thereby unlocked its function. We demonstrate that low-abundance XcpH is the adapter that bridges a trimeric initiating tip complex, XcpIJK, with a periplasmic filament of XcpG subunits. Each pseudopilin protein caps an XcpG protofilament in an overall pseudopilus compatible with dimensions of the periplasm and the outer membrane-spanning secretin through which substrates pass. Unexpectedly, to fulfill its adapter function, the XcpH N-terminal helix must be unwound, a property shared with XcpG subunits. We provide an experimentally validated three-dimensional structural model of a complete type IV filament.
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