1
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Santos MNM, Pintor KL, Hsieh PY, Cheung YW, Sung LK, Shih YL, Lai EM. Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors. Front Microbiol 2024; 15:1351590. [PMID: 38426053 PMCID: PMC10902643 DOI: 10.3389/fmicb.2024.1351590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/22/2024] [Indexed: 03/02/2024] Open
Abstract
The type VI secretion system (T6SS) assembles into a contractile nanomachine to inject effectors across bacterial membranes for secretion. The Agrobacterium tumefaciens species complex is a group of soil inhabitants and phytopathogens that deploys T6SS as an antibacterial weapon against bacterial competitors at both inter-species and intra-species levels. The A. tumefaciens strain 1D1609 genome encodes one main T6SS gene cluster and four vrgG genes (i.e., vgrGa-d), each encoding a spike protein as an effector carrier. A previous study reported that vgrGa-associated gene 2, named v2a, encodes a His-Me finger nuclease toxin (also named HNH/ENDO VII nuclease), contributing to DNase-mediated antibacterial activity. However, the functions and roles of other putative effectors remain unknown. In this study, we identified vgrGc-associated gene 2 (v2c) that encodes another His-Me finger nuclease but with a distinct Serine Histidine Histidine (SHH) motif that differs from the AHH motif of V2a. We demonstrated that the ectopic expression of V2c caused growth inhibition, plasmid DNA degradation, and cell elongation in Escherichia coli using DNAse activity assay and fluorescence microscopy. The cognate immunity protein, V3c, neutralizes the DNase activity and rescues the phenotypes of growth inhibition and cell elongation. Ectopic expression of V2c DNase-inactive variants retains the cell elongation phenotype, while V2a induces cell elongation in a DNase-mediated manner. We also showed that the amino acids of conserved SHH and HNH motifs are responsible for the V2c DNase activity in vivo and in vitro. Notably, V2c also mediated the DNA degradation and cell elongation of the target cell in the context of interbacterial competition. Importantly, V2a and V2c exhibit different capacities against different bacterial species and function synergistically to exert stronger antibacterial activity against the soft rot phytopathogen, Dickeya dadantii.
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Affiliation(s)
- Mary Nia M. Santos
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
- Aquaculture Research and Development Division, Department of Agriculture-National Fisheries Research and Development Institute (DA-NFRDI), Manila, Philippines
| | | | - Pei-Yu Hsieh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yee-Wai Cheung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Li-Kang Sung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
| | - Yu-Ling Shih
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan
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2
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Ishii T, Tsuchida N, Hemelda NM, Saito K, Bao J, Watanabe M, Toyoda A, Matsubara T, Sato M, Toyooka K, Ishihama N, Shirasu K, Matsui H, Toyoda K, Ichinose Y, Hayashi T, Kawaguchi A, Noutoshi Y. Rhizoviticin is an alphaproteobacterial tailocin that mediates biocontrol of grapevine crown gall disease. ISME J 2024; 18:wrad003. [PMID: 38365227 PMCID: PMC10811719 DOI: 10.1093/ismejo/wrad003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/27/2023] [Accepted: 11/06/2023] [Indexed: 02/18/2024]
Abstract
Tailocins are headless phage tail structures that mediate interbacterial antagonism. Although the prototypical tailocins, R- and F-pyocins, in Pseudomonas aeruginosa, and other predominantly R-type tailocins have been studied, their presence in Alphaproteobacteria remains unexplored. Here, we report the first alphaproteobacterial F-type tailocin, named rhizoviticin, as a determinant of the biocontrol activity of Allorhizobium vitis VAR03-1 against crown gall. Rhizoviticin is encoded by a chimeric prophage genome, one providing transcriptional regulators and the other contributing to tail formation and cell lysis, but lacking head formation genes. The rhizoviticin genome retains a nearly intact early phage region containing an integrase remnant and replication-related genes critical for downstream gene transcription, suggesting an ongoing transition of this locus from a prophage to a tailocin-coding region. Rhizoviticin is responsible for the most antagonistic activity in VAR03-1 culture supernatant against pathogenic A. vitis strain, and rhizoviticin deficiency resulted in a significant reduction in the antitumorigenic activity in planta. We identified the rhizoviticin-coding locus in eight additional A. vitis strains from diverse geographical locations, highlighting a unique survival strategy of certain Rhizobiales bacteria in the rhizosphere. These findings advance our understanding of the evolutionary dynamics of tailocins and provide a scientific foundation for employing rhizoviticin-producing strains in plant disease control.
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Affiliation(s)
- Tomoya Ishii
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Natsuki Tsuchida
- Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
- Present address: Division of Biological Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan
| | - Niarsi Merry Hemelda
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Department of Biology, University of Indonesia, Depok 16424, Indonesia
| | - Kirara Saito
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Present address: Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Miyakonojo, Miyazaki 885-0091, Japan
| | - Jiyuan Bao
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Megumi Watanabe
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Atsushi Toyoda
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Takehiro Matsubara
- Okayama University Hospital Biobank, Okayama University Hospital, Okayama 700-8558, Japan
| | - Mayuko Sato
- Mass Spectrometry and Microscopy Unit, Technology Platform Division, RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan
| | - Kiminori Toyooka
- Mass Spectrometry and Microscopy Unit, Technology Platform Division, RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan
| | - Nobuaki Ishihama
- Plant Immunity Research Group, RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan
| | - Ken Shirasu
- Plant Immunity Research Group, RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan
- Graduate School of Science, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hidenori Matsui
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Kazuhiro Toyoda
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Yuki Ichinose
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Tetsuya Hayashi
- Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Akira Kawaguchi
- Western Region Agricultural Research Center (WARC), National Agricultural and Food Research Organization (NARO), Fukuyama, Hiroshima 721-8514, Japan
| | - Yoshiteru Noutoshi
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
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3
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Holland M, Farinella DN, Cruz-Lorenzo E, Laubscher MI, Doakes DA, Ramos MA, Kubota N, Levin TC. L. pneumophila resists its self-harming metabolite HGA via secreted factors and collective peroxide scavenging. mBio 2023; 14:e0120723. [PMID: 37728338 PMCID: PMC10653783 DOI: 10.1128/mbio.01207-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 07/25/2023] [Indexed: 09/21/2023] Open
Abstract
IMPORTANCE Before environmental opportunistic pathogens can infect humans, they must first successfully grow and compete with other microbes in nature, often via secreted antimicrobials. We previously discovered that the bacterium Legionella pneumophila, the causative agent of Legionnaires' disease, can compete with other microbes via a secreted molecule called HGA. Curiously, L. pneumophila strains that produce HGA is not wholly immune to its toxicity, making it a mystery how these bacteria can withstand the "friendly fire" of potentially self-targeting antimicrobials during inter-bacterial battles. Here, we identify several strategies that allow the high-density bacterial populations that secrete HGA to tolerate its effects. Our study clarifies how HGA works. It also points to some explanations of why it is difficult to disinfect L. pneumophila from the built environment and prevent disease outbreaks.
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Affiliation(s)
- Mische Holland
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Danielle N. Farinella
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Emily Cruz-Lorenzo
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Madelyn I. Laubscher
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Darian A. Doakes
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Maria A. Ramos
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Nanami Kubota
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Tera C. Levin
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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4
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Elery ZK, Myers-Morales T, Phillips ED, Garcia EC. Relaxed specificity of BcpB transporters mediates interactions between Burkholderia cepacia complex contact-dependent growth inhibition systems. mSphere 2023; 8:e0030323. [PMID: 37498085 PMCID: PMC10449530 DOI: 10.1128/msphere.00303-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 06/11/2023] [Indexed: 07/28/2023] Open
Abstract
Belonging to the two-partner secretion family of proteins, contact-dependent growth inhibition (CDI) systems mediate interbacterial antagonism among closely related Gram-negative bacteria. The toxic portion of a large surface protein, BcpA/CdiA, is delivered to the cytoplasm of neighboring cells where it inhibits growth. Translocation of the antibacterial polypeptide out of the producing cell requires an associated outer membrane transporter, BcpB/CdiB. Some bacteria, including many Burkholderia species, encode multiple distinct CDI systems, but whether there is interaction between these systems is largely unknown. Using Burkholderia cepacia complex species as a model, here we show that related BcpB transporters exhibit considerable secretion flexibility and can secrete both cognate and non-cognate BcpA substrates. We also identified an additional unique Burkholderia dolosa CDI system capable of mediating interbacterial competition and demonstrated that its BcpB transporter has similar relaxed substrate specificity. Our results showed that two BcpB transporters (BcpB-2 and BcpB-3) were able to secrete all four of the B. dolosa BcpA toxins, while one transporter (BcpB-1) appeared unable to secrete even its cognate BcpA substrate under the tested conditions. This flexibility provided a competitive advantage, as strains lacking the full repertoire of BcpB proteins had decreased CDI activity. Similar results were obtained in Burkholderia multivorans, suggesting that secretion flexibility may be a conserved feature of Burkholderia CDI systems. Together these findings suggest that the interaction between distinct CDI systems enhances the efficiency of bacterial antagonism. IMPORTANCE The Burkholderia cepacia complex (Bcc) is a group of related opportunistic bacterial pathogens that occupy a diverse range of ecological niches and exacerbate disease in patients with underlying conditions. Contact-dependent growth inhibition (CDI) system proteins, produced by Gram-negative bacteria, contain antagonistic properties that allow for intoxication of closely related neighboring bacteria via a secreted protein, BcpA. Multiple unique CDI systems can be found in the same bacterial strain, and here we show that these distinct systems interact in several Bcc species. Our findings suggest that the interaction between CDI system proteins is important for interbacterial toxicity. Understanding the mechanism of interplay between CDI systems provides further insight into the complexity of bacterial antagonism. Moreover, since many bacterial species are predicted to encode multiple CDI systems, this study suggests that interactions between these distinct systems likely contribute to the overall competitive fitness of these species.
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Affiliation(s)
- Zaria K. Elery
- University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | | | - Erica D. Phillips
- University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Erin C. Garcia
- University of Kentucky College of Medicine, Lexington, Kentucky, USA
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5
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Thiery S, Turowski P, Berleman JE, Kaimer C. The predatory soil bacterium Myxococcus xanthus combines a Tad- and an atypical type 3-like protein secretion system to kill bacterial cells. Cell Rep 2022; 40:111340. [PMID: 36103818 DOI: 10.1016/j.celrep.2022.111340] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 06/20/2022] [Accepted: 08/18/2022] [Indexed: 11/03/2022] Open
Abstract
Predatory Myxobacteria employ a multilayered predation strategy to kill and lyse soil microorganisms. Aiming to dissect the mechanism of contact-dependent killing of bacteria, we analyze four protein secretion systems in Myxococcus xanthus and investigate the predation of mutant strains on different timescales. We find that a Tad-like and a type 3-like secretion system (Tad and T3SS∗) fulfill distinct functions during contact-dependent prey killing: the Tad-like system is necessary to induce prey cell death, while the needle-less T3SS∗ initiates prey lysis. Fluorescence microscopy reveals that components of both systems interdependently localize to the predator-prey contact site prior to killing. Swarm expansion assays show that both Tad and T3SS∗ are required to handle live prey and that nutrient extraction from prey bacteria is sufficient to power M. xanthus motility. In conclusion, our observations indicate the functional interplay of two types of secretion systems for killing and lysis of bacterial cells.
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Affiliation(s)
- Susanne Thiery
- Department of Biology and Biotechnology, Microbial Biology, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Pia Turowski
- Department of Biology and Biotechnology, Microbial Biology, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - James E Berleman
- Department of Biology, St. Mary's College, Moraga, CA 94556, USA
| | - Christine Kaimer
- Department of Biology and Biotechnology, Microbial Biology, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
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6
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Elery ZK, Oates AE, Myers-Morales T, Garcia EC. Recipient Cell Factors Influence Interbacterial Competition Mediated by Two Distinct Burkholderia dolosa Contact-Dependent Growth Inhibition Systems. J Bacteriol 2022;:e0054121. [PMID: 36000834 DOI: 10.1128/jb.00541-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Contact-dependent growth inhibition (CDI) systems mediate interbacterial antagonism between Gram-negative bacteria by delivering the toxic portion of a large surface protein (termed BcpA in Burkholderia species) to the cytoplasm of neighboring bacteria. Translocation of the antibacterial polypeptide into recipient cells requires specific recipient outer and inner membrane proteins, but the identity of these factors outside several model organisms is unknown. To identify genes involved in CDI susceptibility in the Burkholderia cepacia complex member Burkholderia dolosa, a transposon mutagenesis selection approach was used to enrich for mutants resistant to BcpA-1 or BcpA-2. Subsequent analysis showed that candidate regulatory genes contributed modestly to recipient cell susceptibility to B. dolosa CDI. However, most candidate deletion mutants did not show the same phenotypes as the corresponding transposon mutants. Whole-genome resequencing revealed that these transposon mutants also contained unique mutations within a three gene locus (wabO, BDAG_01006, and BDAG_01005) encoding predicted lipopolysaccharide (LPS) biosynthesis enzymes. B. dolosa wabO, BDAG_01006, or BDAG_01005 mutants were resistant to CDI and produced LPS with altered core oligosaccharide and O-antigen. Although BcpA-1 and BcpA-2 are dissimilar and expected to utilize different outer membrane receptors, intoxication by both proteins was similarly impacted by LPS changes. Together, these findings suggest that alterations in cellular regulation may indirectly impact the efficiency of CDI-mediated competition and demonstrate that LPS is required for intoxication by two distinct B. dolosa BcpA proteins. IMPORTANCEContact-dependent growth inhibition (CDI) system proteins, produced by many Gram-negative bacteria, are narrow spectrum antimicrobials that inhibit the growth of closely related neighboring bacteria. Here, we use the opportunistic pathogen Burkholderia dolosa to identify genes required for intoxication by two distinct CDI system proteins. Our findings suggest that B. dolosa recipient cells targeted by CDI systems are only intoxicated if they produce full-length lipopolysaccharide. Understanding the mechanisms underlying antagonistic interbacterial interactions may contribute to future therapeutic development.
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7
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Ting SY, LaCourse KD, Ledvina HE, Zhang R, Radey MC, Kulasekara HD, Somavanshi R, Bertolli SK, Gallagher LA, Kim J, Penewit KM, Salipante SJ, Xu L, Peterson SB, Mougous JD. Discovery of coordinately regulated pathways that provide innate protection against interbacterial antagonism. eLife 2022; 11:74658. [PMID: 35175195 PMCID: PMC8926400 DOI: 10.7554/elife.74658] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/16/2022] [Indexed: 11/13/2022] Open
Abstract
Bacterial survival is fraught with antagonism, including that deriving from viruses and competing bacterial cells. It is now appreciated that bacteria mount complex antiviral responses; however, whether a coordinated defense against bacterial threats is undertaken is not well understood. Previously, we showed that Pseudomonas aeruginosa possess a danger-sensing pathway that is a critical fitness determinant during competition against other bacteria. Here, we conducted genome-wide screens in P. aeruginosa that reveal three conserved and widespread interbacterial antagonism resistance clusters (arc1-3). We find that although arc1-3 are coordinately activated by the Gac/Rsm danger-sensing system, they function independently and provide idiosyncratic defense capabilities, distinguishing them from general stress response pathways. Our findings demonstrate that Arc3 family proteins provide specific protection against phospholipase toxins by preventing the accumulation of lysophospholipids in a manner distinct from previously characterized membrane repair systems. These findings liken the response of P. aeruginosa to bacterial threats to that of eukaryotic innate immunity, wherein threat detection leads to the activation of specialized defense systems.
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Affiliation(s)
- See-Yeun Ting
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Kaitlyn D LaCourse
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Hannah E Ledvina
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington School of PharmacySeattleUnited States
| | - Matthew C Radey
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Hemantha D Kulasekara
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Rahul Somavanshi
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Savannah K Bertolli
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Larry A Gallagher
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Jennifer Kim
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Kelsi M Penewit
- Department of Laboratory Medicine and Pathology, University of Washington School of MedicineSeattleUnited States
| | - Stephen J Salipante
- Department of Laboratory Medicine and Pathology, University of Washington School of MedicineSeattleUnited States
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington School of PharmacySeattleUnited States
| | - S Brook Peterson
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Joseph D Mougous
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States,Department of Biochemistry, University of Washington School of MedicineSeattleUnited States,Howard Hughes Medical Institute, University of WashingtonSeattleUnited States
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8
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Oulas A, Zachariou M, Chasapis CT, Tomazou M, Ijaz UZ, Schmartz GP, Spyrou GM, Vlamis-Gardikas A. Putative Antimicrobial Peptides Within Bacterial Proteomes Affect Bacterial Predominance: A Network Analysis Perspective. Front Microbiol 2021; 12:752674. [PMID: 34867874 PMCID: PMC8636115 DOI: 10.3389/fmicb.2021.752674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/11/2021] [Indexed: 11/13/2022] Open
Abstract
The predominance of bacterial taxa in the gut, was examined in view of the putative antimicrobial peptide sequences (AMPs) within their proteomes. The working assumption was that compatible bacteria would share homology and thus immunity to their putative AMPs, while competing taxa would have dissimilarities in their proteome-hidden AMPs. A network-based method ("Bacterial Wars") was developed to handle sequence similarities of predicted AMPs among UniProt-derived protein sequences from different bacterial taxa, while a resulting parameter ("Die" score) suggested which taxa would prevail in a defined microbiome. T he working hypothesis was examined by correlating the calculated Die scores, to the abundance of bacterial taxa from gut microbiomes from different states of health and disease. Eleven publicly available 16S rRNA datasets and a dataset from a full shotgun metagenomics served for the analysis. The overall conclusion was that AMPs encrypted within bacterial proteomes affected the predominance of bacterial taxa in chemospheres.
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Affiliation(s)
- Anastasis Oulas
- Bioinformatics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Margarita Zachariou
- Bioinformatics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Christos T Chasapis
- NMR Center, Instrumental Analysis Laboratory, School of Natural Sciences, University of Patras, Patras, Greece
| | - Marios Tomazou
- Bioinformatics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Umer Z Ijaz
- School of Engineering, University of Glasgow, Glasgow, United Kingdom
| | | | - George M Spyrou
- Bioinformatics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Alexios Vlamis-Gardikas
- Division of Organic Chemistry, Biochemistry and Natural Products, Department of Chemistry, University of Patras, Patras, Greece
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9
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Tran HKR, Grebenc DW, Klein TA, Whitney JC. Bacterial type VII secretion: An important player in host-microbe and microbe-microbe interactions. Mol Microbiol 2021; 115:478-489. [PMID: 33410158 DOI: 10.1111/mmi.14680] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 12/19/2022]
Abstract
Type VII secretion systems (T7SSs) are poorly understood protein export apparatuses found in mycobacteria and many species of Gram-positive bacteria. To date, this pathway has predominantly been studied in Mycobacterium tuberculosis, where it has been shown to play an essential role in virulence; however, much less studied is an evolutionarily divergent subfamily of T7SSs referred to as the T7SSb. The T7SSb is found in the major Gram-positive phylum Firmicutes where it was recently shown to target both eukaryotic and prokaryotic cells, suggesting a dual role for this pathway in host-microbe and microbe-microbe interactions. In this review, we compare the current understanding of the molecular architectures and substrate repertoires of the well-studied mycobacterial T7SSa systems to that of recently characterized T7SSb pathways and highlight how these differences may explain the observed biological functions of this understudied protein export machine.
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Affiliation(s)
- Hiu-Ki R Tran
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Dirk W Grebenc
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Timothy A Klein
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.,David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, ON, Canada
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10
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Klein TA, Grebenc DW, Gandhi SY, Shah VS, Kim Y, Whitney JC. Structure of the Extracellular Region of the Bacterial Type VIIb Secretion System Subunit EsaA. Structure 2020; 29:177-185.e6. [PMID: 33238147 DOI: 10.1016/j.str.2020.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/17/2020] [Accepted: 11/02/2020] [Indexed: 12/15/2022]
Abstract
Gram-positive bacteria use type VII secretion systems (T7SSs) to export effector proteins that manipulate the physiology of nearby prokaryotic and eukaryotic cells. Several mycobacterial T7SSs have established roles in virulence. By contrast, the genetically distinct T7SSb pathway found in Firmicutes bacteria more often functions to mediate bacterial competition. A lack of structural information on the T7SSb has limited the understanding of effector export by this protein secretion apparatus. Here, we present the 2.4 Å crystal structure of the extracellular region of the T7SSb subunit EsaA from Streptococcus gallolyticus. Our structure reveals that homodimeric EsaA is an elongated, arrow-shaped protein with a surface-accessible "tip", which in some species of bacteria serves as a receptor for lytic bacteriophages. Because it is the only T7SSb subunit large enough to traverse the peptidoglycan layer of Firmicutes, we propose that EsaA plays a critical role in transporting effectors across the entirety of the Gram-positive cell envelope.
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Affiliation(s)
- Timothy A Klein
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Dirk W Grebenc
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Shil Y Gandhi
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Vraj S Shah
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Youngchang Kim
- Structural Biology Center, X-ray Science, Argonne National Laboratory, Argonne, IL, USA
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, ON L8S 4K1, Canada.
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Barretto LAF, Fowler CC. Identification of A Putative T6SS Immunity Islet in Salmonella Typhi. Pathogens 2020; 9:pathogens9070559. [PMID: 32664482 PMCID: PMC7400221 DOI: 10.3390/pathogens9070559] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 12/19/2022] Open
Abstract
Typhoid fever is a major global health problem and is the result of systemic infections caused by the human-adapted bacterial pathogen Salmonella enterica serovar Typhi (S. Typhi). The pathology underlying S. Typhi infections significantly differ from infections caused by broad host range serovars of the same species, which are a common cause of gastroenteritis. Accordingly, identifying S. Typhi genetic factors that impart functionality absent from broad host range serovars offers insights into its unique biology. Here, we used an in-silico approach to explore the function of an uncharacterized 14-gene S. Typhi genomic islet. Our results indicated that this islet was specific to the S. enterica species, where it was encoded by the Typhi and Paratyphi A serovars, but was generally absent from non-typhoidal serovars. Evidence was gathered using comparative genomics and sequence analysis tools, and indicated that this islet was comprised of Type VI secretion system (T6SS) and contact-dependent growth inhibition (CDI) genes, the majority of which appeared to encode orphan immunity proteins that protected against the activities of effectors and toxins absent from the S. Typhi genome. We herein propose that this islet represents an immune system that protects S. Typhi against competing bacteria within the human gut.
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Klein TA, Ahmad S, Whitney JC. Contact-Dependent Interbacterial Antagonism Mediated by Protein Secretion Machines. Trends Microbiol 2020; 28:387-400. [PMID: 32298616 DOI: 10.1016/j.tim.2020.01.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/18/2019] [Accepted: 01/16/2020] [Indexed: 12/29/2022]
Abstract
To establish and maintain an ecological niche, bacteria employ a wide range of pathways to inhibit the growth of their microbial competitors. Some of these pathways, such as those that produce antibiotics or bacteriocins, exert toxicity on nearby cells in a cell contact-independent manner. More recently, however, several mechanisms of interbacterial antagonism requiring cell-to-cell contact have been identified. This form of microbial competition is mediated by antibacterial protein toxins whose delivery to target bacteria uses protein secretion apparatuses embedded within the cell envelope of toxin-producing bacteria. In this review, we discuss recent work implicating the bacterial Type I, IV, VI, and VII secretion systems in the export of antibacterial 'effector' proteins that mediate contact-dependent interbacterial antagonism.
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Affiliation(s)
- Timothy A Klein
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Shehryar Ahmad
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1; David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, ON, Canada L8S 4K1.
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Tang JY, Bullen NP, Ahmad S, Whitney JC. Diverse NADase effector families mediate interbacterial antagonism via the type VI secretion system. J Biol Chem 2017; 293:1504-1514. [PMID: 29237732 DOI: 10.1074/jbc.ra117.000178] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/06/2017] [Indexed: 11/06/2022] Open
Abstract
The bacterial type VI secretion system (T6SS) mediates antagonistic cell-cell interactions between competing Gram-negative bacteria. In plant-beneficial bacteria, this pathway has been shown to suppress the growth of bacterial pathogens; however, the identification and mode of action of T6SS effector proteins that mediate this protective effect remain poorly defined. Here, we identify two previously uncharacterized effectors required for interbacterial antagonism by the plant commensal bacterium Pseudomonas protegens Consistent with the established effector-immunity paradigm for antibacterial T6SS substrates, the toxic activities of these effectors are neutralized by adjacently encoded cognate immunity determinants. Although one of these effectors, RhsA, belongs to the family of DNase enzymes, the activity of the other was not apparent from its sequence. To determine the mechanism of toxicity of this latter effector, we determined its 1.3 Å crystal structure in complex with its immunity protein and found that it resembles NAD(P)+-degrading enzymes. In line with this structural similarity, biochemical characterization of this effector, termed Tne2 (Type VI secretion NADase effector family 2), demonstrates that it possesses potent NAD(P)+ hydrolase activity. Tne2 is the founding member of a widespread family of interbacterial NADases predicted to transit not only the Gram-negative T6SS but also the Gram-positive type VII secretion system, a pathway recently implicated in interbacterial competition among Firmicutes. Together, this work identifies new T6SS effectors employed by a plant commensal bacterium to antagonize its competitors and broadly implicates NAD(P)+-hydrolyzing enzymes as substrates of interbacterial conflict pathways found in diverse bacterial phyla.
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Affiliation(s)
- Jenny Y Tang
- From the Michael DeGroote Institute for Infectious Disease Research and.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
| | - Nathan P Bullen
- From the Michael DeGroote Institute for Infectious Disease Research and.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
| | - Shehryar Ahmad
- From the Michael DeGroote Institute for Infectious Disease Research and.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
| | - John C Whitney
- From the Michael DeGroote Institute for Infectious Disease Research and .,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
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