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Liu H, Yu Y, Wang C, Wang Y, Wu R, Zhang Z, Liu D, Liao M, Rong X, Li B, Luo Z, Zhang Z. The molecular mechanism of gspD gene in regulating the biological characteristics, pathogenicity and virulence gene expression of Photobacterium damselae subsp. damselae. Int J Biol Macromol 2025; 306:141559. [PMID: 40020817 DOI: 10.1016/j.ijbiomac.2025.141559] [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: 10/11/2024] [Revised: 01/14/2025] [Accepted: 02/25/2025] [Indexed: 03/03/2025]
Abstract
The pathogenic bacterium Photobacterium damselae subsp. damselae (PDD) has the capacity to infect various mariculture fish species. The Type II secretion system is a component of PDD, facilitating the secretion of extracellular products. The gspD gene encodes the outer membrane secretory channel protein of T2SS. To investigate the role of the gspD gene in T2SS during PDD infection, we generated a gspD gene deletion mutant of PDD (ΔgspD-PDD) using a suicide plasmid-mediated homologous recombination technique and compared the biological characteristics, virulence gene expression, and pathogenicity of ΔgspD-PDD with those of the wild-type strain (WT-PDD). Our results indicated that the hemolytic activity and phospholipase activity of ΔgspD-PDD were significantly diminished compared to WT-PDD, and the complementation strain was restored to levels similar to those of the WT-PDD. The expression levels of T2SS-related genes and the virulence genes were significantly down-regulated, while the outer membrane-related gene and flagella-related genes exhibited significant up-regulation. The LD50 values of ΔgspD-PDD and its ECP in Sebastes schlegelii were 62.70-fold and 18.76-fold higher than those of WT-PDD, respectively. In summary, the mutation of the gspD gene may lead to the down-regulation of T2SS-related genes, resulting in aberrant secretion of ECPs in PDD and subsequently diminishing its pathogenicity.
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Affiliation(s)
- Haozhe Liu
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; College of Fisheries, Tianjin Agricultural University, Tianjin 300392, China
| | - Yongxiang Yu
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; Laboratory for Marine Fisheries Science and Food Production Processes, Laoshan Laboratory Qingdao, Shandong 266237, China
| | - Chunyuan Wang
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China
| | - Yingeng Wang
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; Laboratory for Marine Fisheries Science and Food Production Processes, Laoshan Laboratory Qingdao, Shandong 266237, China
| | - Ronghua Wu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City & Aquaculture Engineering Technology Research Center, College of Fisheries, Southwest University, Chongqing 400715, China
| | - Zhiqi Zhang
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China
| | - Dingyuan Liu
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China
| | - Meijie Liao
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; Laboratory for Marine Fisheries Science and Food Production Processes, Laoshan Laboratory Qingdao, Shandong 266237, China
| | - Xiaojun Rong
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; Laboratory for Marine Fisheries Science and Food Production Processes, Laoshan Laboratory Qingdao, Shandong 266237, China
| | - Bin Li
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; Laboratory for Marine Fisheries Science and Food Production Processes, Laoshan Laboratory Qingdao, Shandong 266237, China
| | - Zhang Luo
- College of Fisheries, Tianjin Agricultural University, Tianjin 300392, China
| | - Zheng Zhang
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academic of Fishery Sciences, Qingdao, Shandong 266071, China; Laboratory for Marine Fisheries Science and Food Production Processes, Laoshan Laboratory Qingdao, Shandong 266237, China.
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2
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Goll S, Martin P, Marillonnet S, Büttner D. Modularization of the type II secretion gene cluster from Xanthomonas euvesicatoria facilitates the identification of a structurally conserved XpsCLM assembly platform complex. PLoS Pathog 2025; 21:e1013008. [PMID: 40202974 PMCID: PMC11981180 DOI: 10.1371/journal.ppat.1013008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2024] [Accepted: 02/26/2025] [Indexed: 04/11/2025] Open
Abstract
Many bacterial pathogens depend on a type II secretion (T2S) system to secrete virulence factors from the periplasm into the extracellular milieu. T2S systems consist of an outer membrane secretin channel, a periplasmic pseudopilus and an inner membrane-associated assembly platform including a cytoplasmic ATPase. The components of T2S systems are often conserved in different bacterial species, however, the architecture of the assembly platform is largely unknown. Here, we analysed predicted assembly platform components of the Xps-T2S system from the plant-pathogenic bacterium Xanthomonas euvesicatoria. To facilitate these studies, we generated a modular xps-T2S gene cluster by Golden Gate assembly of single promoter and gene fragments. The modular design allowed the efficient deletion and replacement of T2S genes and the insertion of reporter fusions. Mutant approaches as well as interaction and crosslinking studies showed that the predicted assembly platform components XpsC, XpsL and XpsM form a trimeric complex which is essential for T2S and associates with the cytoplasmic ATPase XpsE and the secretin XpsD. Structural modeling revealed a similar trimeric architecture of XpsCLM homologs from Pseudomonas, Vibrio and Klebsiella species, despite overall low amino acid sequence similarities. In X. euvesicatoria, crosslinking and fluorescence microscopy studies showed that the formation of the XpsCLM complex is independent of the secretin and vice versa, suggesting that the assembly of the T2S system is a dynamic process which involves the association of preformed subcomplexes.
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Affiliation(s)
- Samuel Goll
- Department of Genetics, Institute for Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Patrick Martin
- Department of Genetics, Institute for Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | | | - Daniela Büttner
- Department of Genetics, Institute for Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
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3
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Cheng J, Tong J, Li C, Wang Z, Li H, Ren M, Song J, Song D, Xie Q, Liu M. Probiotic Characterization of Lactiplantibacillus paraplantarum SDN1.2 and Its Anti-Inflammatory Effect on Klebsiella pneumoniae-Infected Mammary Glands. Vet Sci 2025; 12:323. [PMID: 40284825 PMCID: PMC12031044 DOI: 10.3390/vetsci12040323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2025] [Revised: 03/23/2025] [Accepted: 03/28/2025] [Indexed: 04/29/2025] Open
Abstract
K. pneumoniae is a major cause of bovine mastitis worldwide, making it difficult to control due to its resistance to multiple drugs. L. paraplantarum has been explored as a promising new approach to fighting bovine mastitis. In this study, the probiotic potential and safety of L. paraplantarum SDN1.2, as well as its ex vivo and in vivo anti-inflammatory effects against K. pneumoniae-induced mastitis, were comprehensively investigated using bioinformatics analyses and experimental validation methods. The results revealed that L. paraplantarum SDN1.2 exhibits non-hemolytic activity, is not cytotoxic, lacks virulence genes (e.g., adhesion factors, toxins, and invasion factors) and antibiotic resistance genes (e.g., beta-lactamases and tetracycline resistance genes), as supported by whole-genome sequencing, and significantly inhibits the growth of K. pneumoniae, as evaluated by antimicrobial tests. Following further validation in vitro, L. paraplantarum SDN1.2 demonstrated the capability to inhibit the adhesion and invasion of K. pneumoniae to bMECs. In a mouse model of K. pneumoniae-induced mastitis, L. paraplantarum SDN1.2 reduced the extent of neutrophil infiltration and inflammatory lesions. Furthermore, L. paraplantarum SDN1.2 pretreatment significantly reduced myeloperoxidase (MPO) activity and the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-a) in mouse mammary gland tissue. In K. pneumoniae-infected bMECs, L. paraplantarum SDN1.2 significantly lowered lactate dehydrogenase (LDH) levels and expression of inflammatory cytokines such as IL-6, IL-1β, and TNF-α. The results demonstrated that the newly isolated L. paraplantarum SDN1.2 from bovine sources exhibits promising characteristics as a safe probiotic for the alleviation of bovine mastitis due to its safety profile and anti-inflammatory and antibacterial properties.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Mingchao Liu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Hebei Agricultural University, Baoding 071001, China; (J.T.); (C.L.); (Z.W.); (H.L.); (M.R.); (D.S.); (Q.X.)
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4
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Naskar S, Merino A, Espadas J, Singh J, Roux A, Colom A, Low HH. Mechanism for Vipp1 spiral formation, ring biogenesis, and membrane repair. Nat Struct Mol Biol 2025; 32:571-584. [PMID: 39528797 PMCID: PMC11919738 DOI: 10.1038/s41594-024-01401-8] [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: 10/12/2023] [Accepted: 09/11/2024] [Indexed: 11/16/2024]
Abstract
The ESCRT-III-like protein Vipp1 couples filament polymerization with membrane remodeling. It assembles planar sheets as well as 3D rings and helical polymers, all implicated in mitigating plastid-associated membrane stress. The architecture of Vipp1 planar sheets and helical polymers remains unknown, as do the geometric changes required to transition between polymeric forms. Here we show how cyanobacterial Vipp1 assembles into morphologically-related sheets and spirals on membranes in vitro. The spirals converge to form a central ring similar to those described in membrane budding. Cryo-EM structures of helical filaments reveal a close geometric relationship between Vipp1 helical and planar lattices. Moreover, the helical structures reveal how filaments twist-a process required for Vipp1, and likely other ESCRT-III filaments, to transition between planar and 3D architectures. Overall, our results provide a molecular model for Vipp1 ring biogenesis and a mechanism for Vipp1 membrane stabilization and repair, with implications for other ESCRT-III systems.
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Affiliation(s)
- Souvik Naskar
- Department of Infectious Disease, Imperial College, London, UK
| | - Andrea Merino
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
| | - Javier Espadas
- Biochemistry Department, University of Geneva, Geneva, Switzerland
| | - Jayanti Singh
- Department of Infectious Disease, Imperial College, London, UK
| | - Aurelien Roux
- Biochemistry Department, University of Geneva, Geneva, Switzerland
| | - Adai Colom
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
| | - Harry H Low
- Department of Infectious Disease, Imperial College, London, UK.
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5
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Salvador-Erro J, Pastor Y, Gamazo C. A Recombinant Shigella flexneri Strain Expressing ETEC Heat-Labile Enterotoxin B Subunit Shows Promise for Vaccine Development via OMVs. Int J Mol Sci 2024; 25:12535. [PMID: 39684252 DOI: 10.3390/ijms252312535] [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: 10/31/2024] [Revised: 11/19/2024] [Accepted: 11/20/2024] [Indexed: 12/18/2024] Open
Abstract
Diarrheal diseases caused by Shigella and enterotoxigenic Escherichia coli (ETEC) are significant health burdens, especially in resource-limited regions with high child mortality. In response to the lack of licensed vaccines and rising antibiotic resistance for these pathogens, this study developed a recombinant Shigella flexneri strain with the novel incorporation of the eltb gene for the heat-labile enterotoxin B (LTB) subunit of ETEC directly into Shigella's genome, enhancing stability and consistent production. This approach combines the immunogenic potential of LTB with the antigen delivery properties of S. flexneri outer membrane vesicles (OMVs), aiming to provide cross-protection against both bacterial pathogens in a stable, non-replicating vaccine platform. We confirmed successful expression through GM1-capture ELISA, achieving levels comparable to ETEC. Additionally, proteomic analysis verified that the isolated vesicles from the recombinant strains contain the LTB protein and the main outer membrane proteins and virulence factors from Shigella, including OmpA, OmpC, IcsA, SepA, and Ipa proteins, and increased expression of Slp and OmpX. Thus, our newly designed S. flexneri OMVs, engineered to carry ETEC's LTB toxin, represent a promising strategy to be considered as a subunit vaccine candidate against S. flexneri and ETEC.
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Affiliation(s)
- Josune Salvador-Erro
- Department of Microbiology and Parasitology, Navarra Medical Research Institute (IdiSNA), University of Navarra, 31008 Pamplona, Spain
| | - Yadira Pastor
- Department of Microbiology and Parasitology, Navarra Medical Research Institute (IdiSNA), University of Navarra, 31008 Pamplona, Spain
| | - Carlos Gamazo
- Department of Microbiology and Parasitology, Navarra Medical Research Institute (IdiSNA), University of Navarra, 31008 Pamplona, Spain
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6
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Wimmi S, Fleck M, Helbig C, Brianceau C, Langenfeld K, Szymanski WG, Angelidou G, Glatter T, Diepold A. Pilotins are mobile T3SS components involved in assembly and substrate specificity of the bacterial type III secretion system. Mol Microbiol 2024; 121:304-323. [PMID: 38178634 DOI: 10.1111/mmi.15223] [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: 05/23/2023] [Revised: 12/17/2023] [Accepted: 12/20/2023] [Indexed: 01/06/2024]
Abstract
In animal pathogens, assembly of the type III secretion system injectisome requires the presence of so-called pilotins, small lipoproteins that assist the formation of the secretin ring in the outer membrane. Using a combination of functional assays, interaction studies, proteomics, and live-cell microscopy, we determined the contribution of the pilotin to the assembly, function, and substrate selectivity of the T3SS and identified potential new downstream roles of pilotin proteins. In absence of its pilotin SctG, Yersinia enterocolitica forms few, largely polar injectisome sorting platforms and needles. Accordingly, most export apparatus subcomplexes are mobile in these strains, suggesting the absence of fully assembled injectisomes. Remarkably, while absence of the pilotin all but prevents export of early T3SS substrates, such as the needle subunits, it has little effect on secretion of late T3SS substrates, including the virulence effectors. We found that although pilotins interact with other injectisome components such as the secretin in the outer membrane, they mostly localize in transient mobile clusters in the bacterial membrane. Together, these findings provide a new view on the role of pilotins in the assembly and function of type III secretion injectisomes.
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Affiliation(s)
- Stephan Wimmi
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Moritz Fleck
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Carlos Helbig
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Corentin Brianceau
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Katja Langenfeld
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Witold G Szymanski
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Georgia Angelidou
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Timo Glatter
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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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: 3] [Impact Index Per Article: 3.0] [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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8
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Guilvout I, Samsudin F, Huber RG, Bond PJ, Bardiaux B, Francetic O. Membrane platform protein PulF of the Klebsiella type II secretion system forms a trimeric ion channel essential for endopilus assembly and protein secretion. mBio 2024; 15:e0142323. [PMID: 38063437 PMCID: PMC10790770 DOI: 10.1128/mbio.01423-23] [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: 06/05/2023] [Accepted: 10/24/2023] [Indexed: 01/17/2024] Open
Abstract
IMPORTANCE Type IV pili and type II secretion systems are members of the widespread type IV filament (T4F) superfamily of nanomachines that assemble dynamic and versatile surface fibers in archaea and bacteria. The assembly and retraction of T4 filaments with diverse surface properties and functions require the plasma membrane platform proteins of the GspF/PilC superfamily. Generally considered dimeric, platform proteins are thought to function as passive transmitters of the mechanical energy generated by the ATPase motor, to somehow promote insertion of pilin subunits into the nascent pilus fibers. Here, we generate and experimentally validate structural predictions that support the trimeric state of a platform protein PulF from a type II secretion system. The PulF trimers form selective proton or sodium channels which might energize pilus assembly using the membrane potential. The conservation of the channel sequence and structural features implies a common mechanism for all T4F assembly systems. We propose a model of the oligomeric PulF-PulE ATPase complex that provides an essential framework to investigate and understand the pilus assembly mechanism.
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Affiliation(s)
- Ingrid Guilvout
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
| | | | | | - Peter J. Bond
- Bioinformatics Institute (A-STAR), Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Structural Bioinformatics Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Bacterial Transmembrane Systems Unit, Paris, France
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
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9
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Cooper BF, Ratkevičiūtė G, Clifton LA, Johnston H, Holyfield R, Hardy DJ, Caulton SG, Chatterton W, Sridhar P, Wotherspoon P, Hughes GW, Hall SC, Lovering AL, Knowles TJ. An octameric PqiC toroid stabilises the outer-membrane interaction of the PqiABC transport system. EMBO Rep 2024; 25:82-101. [PMID: 38228789 PMCID: PMC10897342 DOI: 10.1038/s44319-023-00014-4] [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: 08/02/2023] [Revised: 10/31/2023] [Accepted: 11/10/2023] [Indexed: 01/18/2024] Open
Abstract
The E. coli Paraquat Inducible (Pqi) Pathway is a putative Gram-negative phospholipid transport system. The pathway comprises three components: an integral inner membrane protein (PqiA), a periplasmic spanning MCE family protein (PqiB) and an outer membrane lipoprotein (PqiC). Interactions between all complex components, including stoichiometry, remain uncharacterised; nevertheless, once assembled into their quaternary complex, the trio of Pqi proteins are anticipated to provide a continuous channel between the inner and outer membranes of diderms. Here, we present X-ray structures of both the native and a truncated, soluble construct of the PqiC lipoprotein, providing insight into its biological assembly, and utilise neutron reflectometry to characterise the nature of the PqiB-PqiC-membrane interaction. Finally, we employ phenotypic complementation assays to probe specific PqiC residues, which imply the interaction between PqiB and PqiC is less intimate than previously anticipated.
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Affiliation(s)
- Benjamin F Cooper
- Sir William Dunn School of Pathology, University of Oxford, OX1 3RE, Oxford, UK
| | | | - Luke A Clifton
- ISIS Pulsed Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Harwell Oxford Campus, OX11 OQX, Didcot, UK
| | - Hannah Johnston
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Rachel Holyfield
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - David J Hardy
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Simon G Caulton
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - William Chatterton
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Pooja Sridhar
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Peter Wotherspoon
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Gareth W Hughes
- Institute of Cancer and Genomic Sciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Stephen Cl Hall
- ISIS Pulsed Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Harwell Oxford Campus, OX11 OQX, Didcot, UK
| | - Andrew L Lovering
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK
| | - Timothy J Knowles
- School of Biosciences, University of Birmingham, B15 2TT, Birmingham, UK.
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10
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Zehra M, Heo J, Chung JM, Durie CL. Comparative Analysis of T4SS Molecular Architectures. J Microbiol Biotechnol 2023; 33:1543-1551. [PMID: 37528551 PMCID: PMC10772558 DOI: 10.4014/jmb.2307.07006] [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: 07/06/2023] [Revised: 07/21/2023] [Accepted: 07/24/2023] [Indexed: 08/03/2023]
Abstract
The recently published high-resolution R388 T4SS structure provides exciting new details about the complete complex of T4SS, including the components making up the stalk and arches, numerous symmetry mismatches between regions of the complex, and an intriguing interpretation of the closed stalk and radial symmetry of the inner membrane complex, which is related to pilus biogenesis assembly. However, there are a few unidentified densities in the electron microscopy map and portions of the identified component sequences for which the structure is not yet known. It is also unclear how well this minimized DNA-transporting T4SS predicts the structure of other T4SSs, such as expanded systems and those that transport proteins rather than DNA. In this review, we evaluate what can be inferred from the recent high-resolution structure of the R388 T4SS with respect to the Cag and Dot/Icm systems. These systems were selected because, given what is currently known about these systems, we expect them to present most structural differences compared to the R388 T4SS structure. Furthermore, we discuss bacterial physiology and diversity, the T4SS structures and their variations between different bacterial species. These insights may prove beneficial for researchers who elucidate the structure and functions of T4SS in different bacterial species.
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Affiliation(s)
- Mishghan Zehra
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Jiwon Heo
- Department of Biotechnology, The Catholic University of Korea, Bucheon-si 14662, Gyeonggi, Republic of Korea
| | - Jeong Min Chung
- Department of Biotechnology, The Catholic University of Korea, Bucheon-si 14662, Gyeonggi, Republic of Korea
| | - Clarissa L Durie
- Department of Biochemistry, University of Missouri, Columbia, Missouri, 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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Tassinari M, Rudzite M, Filloux A, Low HH. Assembly mechanism of a Tad secretion system secretin-pilotin complex. Nat Commun 2023; 14:5643. [PMID: 37704603 PMCID: PMC10499894 DOI: 10.1038/s41467-023-41200-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 08/25/2023] [Indexed: 09/15/2023] Open
Abstract
The bacterial Tight adherence Secretion System (TadSS) assembles surface pili that drive cell adherence, biofilm formation and bacterial predation. The structure and mechanism of the TadSS is mostly unknown. This includes characterisation of the outer membrane secretin through which the pilus is channelled and recruitment of its pilotin. Here we investigate RcpA and TadD lipoprotein from Pseudomonas aeruginosa. Light microscopy reveals RcpA colocalising with TadD in P. aeruginosa and when heterologously expressed in Escherichia coli. We use cryogenic electron microscopy to determine how RcpA and TadD assemble a secretin channel with C13 and C14 symmetries. Despite low sequence homology, we show that TadD shares a similar fold to the type 4 pilus system pilotin PilF. We establish that the C-terminal four residues of RcpA bind TadD - an interaction essential for secretin formation. The binding mechanism between RcpA and TadD appears distinct from known secretin-pilotin pairings in other secretion systems.
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Affiliation(s)
- Matteo Tassinari
- Department of Infectious Disease, Imperial College, London, SW7 2AZ, UK
- Human Technopole, Milan, Italy
| | - Marta Rudzite
- Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Alain Filloux
- Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Harry H Low
- Department of Infectious Disease, Imperial College, London, SW7 2AZ, UK.
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13
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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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14
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Aguirre-Sánchez JR, Quiñones B, Ortiz-Muñoz JA, Prieto-Alvarado R, Vega-López IF, Martínez-Urtaza J, Lee BG, Chaidez C. Comparative Genomic Analyses of Virulence and Antimicrobial Resistance in Citrobacter werkmanii, an Emerging Opportunistic Pathogen. Microorganisms 2023; 11:2114. [PMID: 37630674 PMCID: PMC10457828 DOI: 10.3390/microorganisms11082114] [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: 07/14/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 08/27/2023] Open
Abstract
Citrobacter werkmanii is an emerging and opportunistic human pathogen found in developing countries and is a causative agent of wound, urinary tract, and blood infections. The present study conducted comparative genomic analyses of a C. werkmanii strain collection from diverse geographical locations and sources to identify the relevant virulence and antimicrobial resistance genes. Pangenome analyses divided the examined C. werkmanii strains into five distinct clades; the subsequent classification identified genes with functional roles in carbohydrate and general metabolism for the core genome and genes with a role in secretion, adherence, and the mobilome for the shell and cloud genomes. A maximum-likelihood phylogenetic tree with a heatmap, showing the virulence and antimicrobial genes' presence or absence, demonstrated the presence of genes with functional roles in secretion systems, adherence, enterobactin, and siderophore among the strains belonging to the different clades. C. werkmanii strains in clade V, predominantly from clinical sources, harbored genes implicated in type II and type Vb secretion systems as well as multidrug resistance to aminoglycoside, beta-lactamase, fluoroquinolone, phenicol, trimethoprim, macrolides, sulfonamide, and tetracycline. In summary, these comparative genomic analyses have demonstrated highly pathogenic and multidrug-resistant genetic profiles in C. werkmanii strains, indicating a virulence potential for this commensal and opportunistic human pathogen.
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Affiliation(s)
- José R. Aguirre-Sánchez
- Laboratorio Nacional para la Investigación en Inocuidad Alimentaria, Centro de Investigación en Alimentación y Desarrollo A.C. (CIAD), Coordinación Regional Culiacán, Culiacan 80110, Mexico;
| | - Beatriz Quiñones
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, USA; (B.Q.); (B.G.L.)
| | - José A. Ortiz-Muñoz
- Parque de Innovación Tecnológica de la Universidad Autónoma de Sinaloa, Culiacan 80040, Mexico; (J.A.O.-M.); (R.P.-A.); (I.F.V.-L.)
| | - Rogelio Prieto-Alvarado
- Parque de Innovación Tecnológica de la Universidad Autónoma de Sinaloa, Culiacan 80040, Mexico; (J.A.O.-M.); (R.P.-A.); (I.F.V.-L.)
| | - Inés F. Vega-López
- Parque de Innovación Tecnológica de la Universidad Autónoma de Sinaloa, Culiacan 80040, Mexico; (J.A.O.-M.); (R.P.-A.); (I.F.V.-L.)
| | - Jaime Martínez-Urtaza
- Departament de Genètica i de Microbiologia, Universitat Autờnoma de Barcelona, 08193 Bellaterra, Spain;
| | - Bertram G. Lee
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, USA; (B.Q.); (B.G.L.)
| | - Cristóbal Chaidez
- Laboratorio Nacional para la Investigación en Inocuidad Alimentaria, Centro de Investigación en Alimentación y Desarrollo A.C. (CIAD), Coordinación Regional Culiacán, Culiacan 80110, Mexico;
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15
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Ryan ME, Damke PP, Bryant C, Sheedlo MJ, Shaffer CL. Architectural asymmetry enables DNA transport through the Helicobacter pylori cag type IV secretion system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550604. [PMID: 37546756 PMCID: PMC10402047 DOI: 10.1101/2023.07.25.550604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Structural asymmetry within secretion system architecture is fundamentally important for apparatus diversification and biological function. However, the mechanism by which symmetry mismatch contributes to nanomachine assembly and interkingdom effector translocation are undefined. Here, we show that architectural asymmetry orchestrates dynamic substrate selection and enables trans-kingdom DNA conjugation through the Helicobacter pylori cag type IV secretion system (cag T4SS). Structural analyses of asymmetric units within the cag T4SS periplasmic ring complex (PRC) revealed intermolecular π-π stacking interactions that coordinate DNA binding and license trans-kingdom conjugation without disrupting the translocation of protein and peptidoglycan effector molecules. Additionally, we identified a novel proximal translocation channel gating mechanism that regulates cargo loading and governs substrate transport across the outer membrane. We thus propose a model whereby the organization and geometry of architectural symmetry mismatch exposes π-π interfaces within the PRC to facilitate DNA transit through the cag T4SS translocation channel.
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Affiliation(s)
- Mackenzie E. Ryan
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Prashant P. Damke
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, KY, 40546, USA
| | - Caitlynn Bryant
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, KY, 40546, USA
| | - Michael J. Sheedlo
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Carrie L. Shaffer
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, KY, 40546, USA
- Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, KY, 40536, USA
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
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16
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Bonczarowska JH, Susat J, Krause-Kyora B, Dangvard Pedersen D, Boldsen J, Larsen LA, Seeberg L, Nebel A, Unterweger D. Ancient Yersinia pestis genomes lack the virulence-associated Ypf Φ prophage present in modern pandemic strains. Proc Biol Sci 2023; 290:20230622. [PMID: 37464758 PMCID: PMC10354491 DOI: 10.1098/rspb.2023.0622] [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: 05/15/2023] [Accepted: 06/19/2023] [Indexed: 07/20/2023] Open
Abstract
Yersinia pestis is the causative agent of at least three major plague pandemics (Justinianic, Medieval and Modern). Previous studies on ancient Y. pestis genomes revealed that several genomic alterations had occurred approximately 5000-3000 years ago and contributed to the remarkable virulence of this pathogen. How a subset of strains evolved to cause the Modern pandemic is less well-understood. Here, we examined the virulence-associated prophage (YpfΦ), which had been postulated to be exclusively present in the genomes of strains associated with the Modern pandemic. The analysis of two new Y. pestis genomes from medieval/early modern Denmark confirmed that the phage is absent from the genome of strains dating to this time period. An extended comparative genome analysis of over 300 strains spanning more than 5000 years showed that the prophage is found in the genomes of modern strains only and suggests an integration into the genome during recent Y. pestis evolution. The phage-encoded Zot protein showed structural homology to a virulence factor of Vibrio cholerae. Similar to modern Y. pestis, we observed phages with a common origin to YpfΦ in individual strains of other bacterial species. Our findings present an updated view on the prevalence of YpfΦ, which might contribute to our understanding of the host spectrum, geographical spread and virulence of Y. pestis responsible for the Modern pandemic.
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Affiliation(s)
- Joanna H. Bonczarowska
- Institute of Clinical Molecular Biology, Kiel University, Rosalind-Franklin-Straße 12, Kiel 24105, Germany
| | - Julian Susat
- Institute of Clinical Molecular Biology, Kiel University, Rosalind-Franklin-Straße 12, Kiel 24105, Germany
| | - Ben Krause-Kyora
- Institute of Clinical Molecular Biology, Kiel University, Rosalind-Franklin-Straße 12, Kiel 24105, Germany
| | - Dorthe Dangvard Pedersen
- Unit of Anthropology, Department of Forensic Medicine, University of Southern Denmark, Odense M, 5230, Denmark
| | - Jesper Boldsen
- Unit of Anthropology, Department of Forensic Medicine, University of Southern Denmark, Odense M, 5230, Denmark
| | | | - Lone Seeberg
- Museum Horsens Arkæologisk Afdeling, Fussingsvej 8, Horsens 8700, Denmark
| | - Almut Nebel
- Institute of Clinical Molecular Biology, Kiel University, Rosalind-Franklin-Straße 12, Kiel 24105, Germany
| | - Daniel Unterweger
- Institute for Experimental Medicine, Kiel University, Michaelisstraße 5, Kiel 24105, Germany
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, Plön 24306, Germany
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17
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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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18
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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: 0.5] [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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19
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Pelicic V. Mechanism of assembly of type 4 filaments: everything you always wanted to know (but were afraid to ask). MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36947586 DOI: 10.1099/mic.0.001311] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Type 4 filaments (T4F) are a superfamily of filamentous nanomachines - virtually ubiquitous in prokaryotes and functionally versatile - of which type 4 pili (T4P) are the defining member. T4F are polymers of type 4 pilins, assembled by conserved multi-protein machineries. They have long been an important topic for research because they are key virulence factors in numerous bacterial pathogens. Our poor understanding of the molecular mechanisms of T4F assembly is a serious hindrance to the design of anti-T4F therapeutics. This review attempts to shed light on the fundamental mechanistic principles at play in T4F assembly by focusing on similarities rather than differences between several (mostly bacterial) T4F. This holistic approach, complemented by the revolutionary ability of artificial intelligence to predict protein structures, led to an intriguing mechanistic model of T4F assembly.
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Affiliation(s)
- Vladimir Pelicic
- Laboratoire de Chimie Bactérienne, UMR 7283 CNRS/Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, Marseille, France
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20
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Garnett JA. I shall be released: Assembly platform dynamics during type II secretion. Structure 2023; 31:123-125. [PMID: 36736296 DOI: 10.1016/j.str.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this issue of Structure, Dazzoni et al. solve the high-resolution homo- and hetero-dimeric structures of the Klebsiella oxytoca PulL and PulM C-terminal domains and unravel an uncharacterized dynamic interaction interface that is required for correct function of the type II secretion system.
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Affiliation(s)
- James A Garnett
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London, UK.
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21
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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: 2.0] [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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22
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Barbat B, Douzi B, Voulhoux R. Structural lessons on bacterial secretins. Biochimie 2023; 205:110-116. [PMID: 36096236 DOI: 10.1016/j.biochi.2022.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/26/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022]
Abstract
To exchange and communicate with their surroundings, bacteria have evolved multiple active and passive mechanisms for trans-envelope transport. Among the pore-forming complexes found in the outer membrane of Gram-negative bacteria, secretins are distinctive homo-oligomeric channels dedicated to the active translocation of voluminous structures such as folded proteins, assembled fibers, virus particles or DNA. Members of the bacterial secretin family share a common cylinder-shaped structure with a gated pore-forming part inserted in the outer membrane, and a periplasmic channel connected to the inner membrane components of the corresponding nanomachine. In this mini-review, we will present what recently determined 3D structures have told us about the mechanisms of translocation through secretins of large substrates to the bacterial surface or in the extracellular milieu.
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Affiliation(s)
- Brice Barbat
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, 13009, Marseille, France
| | | | - Romé Voulhoux
- LCB-UMR7283, CNRS, Aix Marseille Université, IMM, 13009, Marseille, France.
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23
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Type IV Pili Are a Critical Virulence Factor in Clinical Isolates of Paenibacillus thiaminolyticus. mBio 2022; 13:e0268822. [PMID: 36374038 PMCID: PMC9765702 DOI: 10.1128/mbio.02688-22] [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: 11/16/2022] Open
Abstract
Hydrocephalus, the leading indication for childhood neurosurgery worldwide, is particularly prevalent in low- and middle-income countries. Hydrocephalus preceded by an infection, or postinfectious hydrocephalus, accounts for up to 60% of hydrocephalus in these areas. Since many children with hydrocephalus suffer poor long-term outcomes despite surgical intervention, prevention of hydrocephalus remains paramount. Our previous studies implicated a novel bacterial pathogen, Paenibacillus thiaminolyticus, as a causal agent of neonatal sepsis and postinfectious hydrocephalus in Uganda. Here, we report the isolation of three P. thiaminolyticus strains, Mbale, Mbale2, and Mbale3, from patients with postinfectious hydrocephalus. We constructed complete genome assemblies of the clinical isolates as well as the nonpathogenic P. thiaminolyticus reference strain and performed comparative genomic and proteomic analyses to identify potential virulence factors. All three isolates carry a unique beta-lactamase gene, and two of the three isolates exhibit resistance in culture to the beta-lactam antibiotics penicillin and ampicillin. In addition, a cluster of genes carried on a mobile genetic element that encodes a putative type IV pilus operon is present in all three clinical isolates but absent in the reference strain. CRISPR-mediated deletion of the gene cluster substantially reduced the virulence of the Mbale strain in mice. Comparative proteogenomic analysis identified various additional potential virulence factors likely acquired on mobile genetic elements in the virulent strains. These results provide insight into the emergence of virulence in P. thiaminolyticus and suggest avenues for the diagnosis and treatment of this novel bacterial pathogen. IMPORTANCE Postinfectious hydrocephalus, a devastating sequela of neonatal infection, is associated with increased childhood mortality and morbidity. A novel bacterial pathogen, Paenibacillus thiaminolyticus, is highly associated with postinfectious hydrocephalus in an African cohort. Whole-genome sequencing, RNA sequencing, and proteomics of clinical isolates and a reference strain in combination with CRISPR editing identified type IV pili as a critical virulence factor for P. thiaminolyticus infection. Acquisition of a type IV pilus-encoding mobile genetic element critically contributed to converting a nonpathogenic strain of P. thiaminolyticus into a pathogen capable of causing devastating diseases. Given the widespread presence of type IV pilus in pathogens, the presence of the type IV pilus operon could serve as a diagnostic and therapeutic target in P. thiaminolyticus and related bacteria.
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Cardoso JLS, Souza AA, Vieira MLC. Molecular basis for host responses to Xanthomonas infection. PLANTA 2022; 256:84. [PMID: 36114308 DOI: 10.1007/s00425-022-03994-0] [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: 03/25/2022] [Accepted: 09/05/2022] [Indexed: 06/15/2023]
Abstract
This review highlights the most relevant and recent updated information available on the defense responses of selected hosts against Xanthomonas spp. Xanthomonas is one of the most important genera of Gram-negative phytopathogenic bacteria, severely affecting the productivity of economically important crops worldwide, colonizing either the vascular system or the mesophyll tissue of the host. Due to its rapid propagation, Xanthomonas poses an enormous challenge to farmers, because it is usually controlled using huge quantities of copper-based chemicals, adversely impacting the environment. Thus, developing new ways of preventing colonization by these bacteria has become essential. Advances in genomic and transcriptomic technologies have significantly elucidated at molecular level interactions between various crops and Xanthomonas species. Understanding how these hosts respond to the infection is crucial if we are to exploit potential approaches for improving crop breeding and cutting productivity losses. This review focuses on our current knowledge of the defense response mechanisms in agricultural crops after Xanthomonas infection. We describe the molecular basis of host-bacterium interactions over a broad spectrum with the aim of improving our fundamental understanding of which genes are involved and how they work in this interaction, providing information that can help to speed up plant breeding programs, namely using gene editing approaches.
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Affiliation(s)
- Jéssica L S Cardoso
- Genetics Department, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Piracicaba, SP, 13418-900, Brazil
| | - Alessandra A Souza
- Citrus Research Center "Sylvio Moreira", Agronomic Institute (IAC), Cordeirópolis, SP, 13490-000, Brazil
| | - Maria Lucia C Vieira
- Genetics Department, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Piracicaba, SP, 13418-900, Brazil.
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25
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Hughes-Games A, Davis SA, Hill DJ. Direct visualization of sequence-specific DNA binding by gonococcal type IV pili. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35920810 DOI: 10.1099/mic.0.001224] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neisseria gonorrhoeae, the causative agent of gonorrhoea, is a major burden on global healthcare systems, with an estimated ~80-90 million new global cases annually. This burden is exacerbated by increasing levels of antimicrobial resistance, which has greatly limited viable antimicrobial therapies. Decreasing gonococcal drug susceptibility has been driven largely by accumulation of chromosomal resistance determinants, which can be acquired through natural transformation, whereby DNA in the extracellular milieu is imported into cells and incorporated into the genome by homologous recombination. N. gonorrhoeae possesses a specialized system for DNA uptake, which strongly biases transformation in favour of DNA from closely related bacteria by recognizing a 10-12 bp DNA uptake sequence (DUS) motif, which is highly overrepresented in their chromosomal DNA. This process relies on numerous proteins, including the DUS-specific receptor ComP, which assemble retractile protein filaments termed type IV pili (T4P) extending from the cell surface, and one model for neisserial DNA uptake proposes that these filaments bind DNA in a DUS-dependent manner before retracting to transport DNA into the periplasm. However, conflicting evidence indicates that elongated pilus filaments may not have such a direct role in DNA binding uptake as this model suggests. Here, we quantitatively measured DNA binding to gonococcal T4P fibres by directly visualizing binding complexes with confocal fluorescence microscopy in order to confirm the sequence-specific, comP-dependent DNA binding capacity of elongated T4P fibres. This supports the idea that pilus filaments could be responsible for initially capturing DNA in the first step of sequence-specific DNA uptake.
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Affiliation(s)
- Alex Hughes-Games
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK.,Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Bristol, UK.,School of Chemistry, University of Bristol, Bristol, UK
| | - Sean A Davis
- School of Chemistry, University of Bristol, Bristol, UK
| | - Darryl J Hill
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
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26
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Abstract
Bacterial type IV secretion systems (T4SSs) are a versatile group of nanomachines that can horizontally transfer DNA through conjugation and deliver effector proteins into a wide range of target cells. The components of T4SSs in gram-negative bacteria are organized into several large subassemblies: an inner membrane complex, an outer membrane core complex, and, in some species, an extracellular pilus. Cryo-electron tomography has been used to define the structures of T4SSs in intact bacteria, and high-resolution structural models are now available for isolated core complexes from conjugation systems, the Xanthomonas citri T4SS, the Helicobacter pylori Cag T4SS, and the Legionella pneumophila Dot/Icm T4SS. In this review, we compare the molecular architectures of these T4SSs, focusing especially on the structures of core complexes. We discuss structural features that are shared by multiple T4SSs as well as evolutionary strategies used for T4SS diversification. Finally, we discuss how structural variations among T4SSs may confer specialized functional properties.
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Affiliation(s)
- Michael J. Sheedlo
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Melanie D. Ohi
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
| | - Timothy L. Cover
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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27
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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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28
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Liu X, Khara P, Baker ML, Christie PJ, Hu B. Structure of a type IV secretion system core complex encoded by multi-drug resistance F plasmids. Nat Commun 2022; 13:379. [PMID: 35046412 PMCID: PMC8770708 DOI: 10.1038/s41467-022-28058-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 01/04/2022] [Indexed: 11/09/2022] Open
Abstract
Bacterial type IV secretion systems (T4SSs) are largely responsible for the proliferation of multi-drug resistance. We solved the structure of the outer-membrane core complex (OMCCF) of a T4SS encoded by a conjugative F plasmid at <3.0 Å resolution by cryoelectron microscopy. The OMCCF consists of a 13-fold symmetrical outer ring complex (ORC) built from 26 copies of TraK and TraV C-terminal domains, and a 17-fold symmetrical central cone (CC) composed of 17 copies of TraB β-barrels. Domains of TraV and TraB also bind the CC and ORC substructures, establishing that these proteins undergo an intraprotein symmetry alteration to accommodate the C13:C17 symmetry mismatch. We present evidence that other pED208-encoded factors stabilize the C13:C17 architecture and define the importance of TraK, TraV and TraB domains to T4SSF function. This work identifies OMCCF structural motifs of proposed importance for structural transitions associated with F plasmid dissemination and F pilus biogenesis.
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Affiliation(s)
- Xiangan Liu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Pratick Khara
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Matthew L Baker
- Department of Biochemistry and Molecular Biology, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA.
| | - Bo Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA.
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29
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Tejedor AR, Garaizar A, Ramírez J, Espinosa JR. 'RNA modulation of transport properties and stability in phase-separated condensates. Biophys J 2021; 120:5169-5186. [PMID: 34762868 DOI: 10.1101/2021.03.05.434111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/03/2021] [Indexed: 05/25/2023] Open
Abstract
One of the key mechanisms employed by cells to control their spatiotemporal organization is the formation and dissolution of phase-separated condensates. The balance between condensate assembly and disassembly can be critically regulated by the presence of RNA. In this work, we use a chemically-accurate sequence-dependent coarse-grained model for proteins and RNA to unravel the impact of RNA in modulating the transport properties and stability of biomolecular condensates. We explore the phase behavior of several RNA-binding proteins such as FUS, hnRNPA1, and TDP-43 proteins along with that of their corresponding prion-like domains and RNA recognition motifs from absence to moderately high RNA concentration. By characterizing the phase diagram, key molecular interactions, surface tension, and transport properties of the condensates, we report a dual RNA-induced behavior: on the one hand, RNA enhances phase separation at low concentration as long as the RNA radius of gyration is comparable to that of the proteins, whereas at high concentration, it inhibits the ability of proteins to self-assemble independently of its length. On the other hand, along with the stability modulation, the viscosity of the condensates can be considerably reduced at high RNA concentration as long as the length of the RNA chains is shorter than that of the proteins. Conversely, long RNA strands increase viscosity even at high concentration, but barely modify protein self-diffusion which mainly depends on RNA concentration and on the effect RNA has on droplet density. On the whole, our work rationalizes the different routes by which RNA can regulate phase separation and condensate dynamics, as well as the subsequent aberrant rigidification implicated in the emergence of various neuropathologies and age-related diseases.
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Affiliation(s)
- Andrés R Tejedor
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain
| | - Adiran Garaizar
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Jorge Ramírez
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain.
| | - Jorge R Espinosa
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom.
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30
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Conners R, McLaren M, Łapińska U, Sanders K, Stone MRL, Blaskovich MAT, Pagliara S, Daum B, Rakonjac J, Gold VAM. CryoEM structure of the outer membrane secretin channel pIV from the f1 filamentous bacteriophage. Nat Commun 2021; 12:6316. [PMID: 34728631 PMCID: PMC8563730 DOI: 10.1038/s41467-021-26610-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 11/09/2022] Open
Abstract
The Ff family of filamentous bacteriophages infect gram-negative bacteria, but do not cause lysis of their host cell. Instead, new virions are extruded via the phage-encoded pIV protein, which has homology with bacterial secretins. Here, we determine the structure of pIV from the f1 filamentous bacteriophage at 2.7 Å resolution by cryo-electron microscopy, the first near-atomic structure of a phage secretin. Fifteen f1 pIV subunits assemble to form a gated channel in the bacterial outer membrane, with associated soluble domains projecting into the periplasm. We model channel opening and propose a mechanism for phage egress. By single-cell microfluidics experiments, we demonstrate the potential for secretins such as pIV to be used as adjuvants to increase the uptake and efficacy of antibiotics in bacteria. Finally, we compare the f1 pIV structure to its homologues to reveal similarities and differences between phage and bacterial secretins.
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Affiliation(s)
- Rebecca Conners
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Kelly Sanders
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Jasna Rakonjac
- School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Exeter, UK.
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK.
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31
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Sheedlo MJ, Durie CL, Chung JM, Chang L, Roberts J, Swanson M, Lacy DB, Ohi MD. Cryo-EM reveals new species-specific proteins and symmetry elements in the Legionella pneumophila Dot/Icm T4SS. eLife 2021; 10:e70427. [PMID: 34519271 PMCID: PMC8486379 DOI: 10.7554/elife.70427] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 09/14/2021] [Indexed: 01/21/2023] Open
Abstract
Legionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia known as Legionnaires' disease. The pathology associated with infection depends on bacterial delivery of effector proteins into the host via the membrane spanning Dot/Icm type IV secretion system (T4SS). We have determined sub-3.0 Å resolution maps of the Dot/Icm T4SS core complex by single particle cryo-EM. The high-resolution structural analysis has allowed us to identify proteins encoded outside the Dot/Icm genetic locus that contribute to the core T4SS structure. We can also now define two distinct areas of symmetry mismatch, one that connects the C18 periplasmic ring (PR) and the C13 outer membrane cap (OMC) and one that connects the C13 OMC with a 16-fold symmetric dome. Unexpectedly, the connection between the PR and OMC is DotH, with five copies sandwiched between the OMC and PR to accommodate the symmetry mismatch. Finally, we observe multiple conformations in the reconstructions that indicate flexibility within the structure.
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Affiliation(s)
- Michael J Sheedlo
- Department of Pharmacology, University of MinnesotaMinneapolisUnited States
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical CenterNashvilleUnited States
| | - Clarissa L Durie
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Jeong Min Chung
- Life Sciences Institute, University of MichiganAnn ArborUnited States
- Department of Biotechnology, The Catholic University of KoreaGyeonggiRepublic of Korea
| | - Louise Chang
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Jacquelyn Roberts
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Michele Swanson
- Department of Microbiology and Immunology, University Of MichiganAnn ArborUnited States
| | - Dana Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical CenterNashvilleUnited States
- The Veterans Affairs Tennessee Valley Healthcare SystemNasvhilleUnited States
| | - Melanie D Ohi
- Life Sciences Institute, University of MichiganAnn ArborUnited States
- Department of Cell and Developmental Biology, University of MichiganAnn ArborUnited States
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32
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Liu J, Tassinari M, Souza DP, Naskar S, Noel JK, Bohuszewicz O, Buck M, Williams TA, Baum B, Low HH. Bacterial Vipp1 and PspA are members of the ancient ESCRT-III membrane-remodeling superfamily. Cell 2021; 184:3660-3673.e18. [PMID: 34166615 PMCID: PMC8281802 DOI: 10.1016/j.cell.2021.05.041] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 11/24/2020] [Accepted: 05/25/2021] [Indexed: 12/31/2022]
Abstract
Membrane remodeling and repair are essential for all cells. Proteins that perform these functions include Vipp1/IM30 in photosynthetic plastids, PspA in bacteria, and ESCRT-III in eukaryotes. Here, using a combination of evolutionary and structural analyses, we show that these protein families are homologous and share a common ancient evolutionary origin that likely predates the last universal common ancestor. This homology is evident in cryo-electron microscopy structures of Vipp1 rings from the cyanobacterium Nostoc punctiforme presented over a range of symmetries. Each ring is assembled from rungs that stack and progressively tilt to form dome-shaped curvature. Assembly is facilitated by hinges in the Vipp1 monomer, similar to those in ESCRT-III proteins, which allow the formation of flexible polymers. Rings have an inner lumen that is able to bind and deform membranes. Collectively, these data suggest conserved mechanistic principles that underlie Vipp1, PspA, and ESCRT-III-dependent membrane remodeling across all domains of life.
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Affiliation(s)
- Jiwei Liu
- Department of Infectious Disease, Imperial College, London, UK
| | | | - Diorge P Souza
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK; Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Souvik Naskar
- Department of Infectious Disease, Imperial College, London, UK
| | - Jeffrey K Noel
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | | | - Martin Buck
- Department of Life Sciences, Imperial College, London, UK
| | - Tom A Williams
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK; Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, UK; Institute for the Physics of Living Systems, University College London, London, UK.
| | - Harry H Low
- Department of Infectious Disease, Imperial College, London, UK.
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33
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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: 3.5] [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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34
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Horváthová L, Žárský V, Pánek T, Derelle R, Pyrih J, Motyčková A, Klápšťová V, Vinopalová M, Marková L, Voleman L, Klimeš V, Petrů M, Vaitová Z, Čepička I, Hryzáková K, Harant K, Gray MW, Chami M, Guilvout I, Francetic O, Franz Lang B, Vlček Č, Tsaousis AD, Eliáš M, Doležal P. Analysis of diverse eukaryotes suggests the existence of an ancestral mitochondrial apparatus derived from the bacterial type II secretion system. Nat Commun 2021; 12:2947. [PMID: 34011950 PMCID: PMC8134430 DOI: 10.1038/s41467-021-23046-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 03/22/2021] [Indexed: 12/14/2022] Open
Abstract
The type 2 secretion system (T2SS) is present in some Gram-negative eubacteria and used to secrete proteins across the outer membrane. Here we report that certain representative heteroloboseans, jakobids, malawimonads and hemimastigotes unexpectedly possess homologues of core T2SS components. We show that at least some of them are present in mitochondria, and their behaviour in biochemical assays is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). We additionally identified 23 protein families co-occurring with miT2SS in eukaryotes. Seven of these proteins could be directly linked to the core miT2SS by functional data and/or sequence features, whereas others may represent different parts of a broader functional pathway, possibly also involving the peroxisome. Its distribution in eukaryotes and phylogenetic evidence together indicate that the miT2SS-centred pathway is an ancestral eukaryotic trait. Our findings thus have direct implications for the functional properties of the early mitochondrion. Bacteria use the type 2 secretion system to secrete enzymes and toxins across the outer membrane to the environment. Here the authors analyse the T2SS pathway in three protist lineages and suggest that the early mitochondrion may have been capable of secreting proteins into the cytosol.
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Affiliation(s)
- Lenka Horváthová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vojtěch Žárský
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Tomáš Pánek
- Faculty of Science, Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic.,Faculty of Science, Department of Zoology, Charles University, Prague 2, Czech Republic
| | - Romain Derelle
- School of Biosciences, University of Birmingham, Edgbaston, UK
| | - Jan Pyrih
- Laboratory of Molecular & Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, UK.,Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Alžběta Motyčková
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Veronika Klápšťová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Martina Vinopalová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Lenka Marková
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Luboš Voleman
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vladimír Klimeš
- Faculty of Science, Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic
| | - Markéta Petrů
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Zuzana Vaitová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Ivan Čepička
- Faculty of Science, Department of Zoology, Charles University, Prague 2, Czech Republic
| | - Klára Hryzáková
- Faculty of Science, Department of Genetics and Microbiology, Charles University, Prague 2, Czech Republic
| | - Karel Harant
- Faculty of Science, Proteomic core facility, Charles University, BIOCEV, Vestec, Czech Republic
| | - Michael W Gray
- Department of Biochemistry and Molecular Biology and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada
| | - Mohamed Chami
- Center for Cellular Imaging and NanoAnalytics, University of Basel, Basel, Switzerland
| | - Ingrid Guilvout
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - B Franz Lang
- Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montreal, QC, Canada
| | - Čestmír Vlček
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague 4, Czech Republic
| | - Anastasios D Tsaousis
- Laboratory of Molecular & Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, UK
| | - Marek Eliáš
- Faculty of Science, Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic.
| | - Pavel Doležal
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic.
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35
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Zhang X, Sun J, Chen F, Qi H, Chen L, Sung YY, Huang Y, Lv A, Hu X. Phenotypic and genomic characterization of a Vibrio parahaemolyticus strain causing disease in Penaeus vannamei provides insights into its niche adaptation and pathogenic mechanism. Microb Genom 2021; 7. [PMID: 33952389 PMCID: PMC8209731 DOI: 10.1099/mgen.0.000549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The virulence of Vibrio parahaemolyticus is variable depending on its virulence determinants. A V. parahaemolyticus strain, in which the virulence is governed by the pirA and pirB genes, can cause acute hepatopancreatic necrosis disease (AHPND) in shrimps. Some V. parahaemolyticus that are non-AHPND strains also cause shrimp diseases and result in huge economic losses, while their pathogenicity and pathogenesis remain unclear. In this study, a non-AHPND V. parahaemolyticus, TJA114, was isolated from diseased Penaeus vannamei associated with a high mortality. To understand its virulence and adaptation to the external environment, whole-genome sequencing of this isolate was conducted, and its phenotypic profiles including pathogenicity, growth characteristics and nutritional requirements were investigated. Shrimps following artificial infection with this isolate presented similar clinical symptoms to the naturally diseased ones and generated obvious pathological lesions. The growth characteristics indicated that the isolate TJA114 could grow well under different salinity (10–55 p.p.t.), temperature (23–37 °C) and pH (6–10) conditions. Phenotype MicroArray results showed that this isolate could utilize a variety of carbon sources, amino acids and a range of substrates to help itself adapt to the high hyperosmotic and alkaline environments. Antimicrobial-susceptibility test showed that it was a multidrug-resistant bacterium. The whole-genomic analysis showed that this V. parahaemolyticus possessed many important functional genes associated with multidrug resistance, stress response, adhesions, haemolysis, putative secreted proteases, dedicated protein secretion systems and a variety of nutritional metabolic mechanisms. These annotated functional genes were confirmed by the phenotypic profiles. The results in this study indicated that this V. parahaemolyticus isolate possesses a high pathogenicity and strong environmental adaptability.
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Affiliation(s)
- Xue Zhang
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
| | - Jingfeng Sun
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
| | - Feng Chen
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
| | - Hongli Qi
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
| | - Limei Chen
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
| | - Yeong Yik Sung
- Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu 21030, Malaysia
| | - Yadong Huang
- Tianjin Hengqian Aquaculture Co. Ltd, Tianjin 300270, PR China
| | - Aijun Lv
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
| | - Xiucai Hu
- Tianjin Key Laboratory of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin 300384, PR China
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36
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Grishin A, Voth K, Gagarinova A, Cygler M. Structural biology of the invasion arsenal of Gram-negative bacterial pathogens. FEBS J 2021; 289:1385-1427. [PMID: 33650300 DOI: 10.1111/febs.15794] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 02/11/2021] [Accepted: 02/26/2021] [Indexed: 12/20/2022]
Abstract
In the last several years, there has been a tremendous progress in the understanding of host-pathogen interactions and the mechanisms by which bacterial pathogens modulate behavior of the host cell. Pathogens use secretion systems to inject a set of proteins, called effectors, into the cytosol of the host cell. These effectors are secreted in a highly regulated, temporal manner and interact with host proteins to modify a multitude of cellular processes. The number of effectors varies between pathogens from ~ 30 to as many as ~ 350. The functional redundancy of effectors encoded by each pathogen makes it difficult to determine the cellular effects or function of individual effectors, since their individual knockouts frequently produce no easily detectable phenotypes. Structural biology of effector proteins and their interactions with host proteins, in conjunction with cell biology approaches, has provided invaluable information about the cellular function of effectors and underlying molecular mechanisms of their modes of action. Many bacterial effectors are functionally equivalent to host proteins while being structurally divergent from them. Other effector proteins display new, previously unobserved functionalities. Here, we summarize the contribution of the structural characterization of effectors and effector-host protein complexes to our understanding of host subversion mechanisms used by the most commonly investigated Gram-negative bacterial pathogens. We describe in some detail the enzymatic activities discovered among effector proteins and how they affect various cellular processes.
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Affiliation(s)
- Andrey Grishin
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Kevin Voth
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Alla Gagarinova
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Miroslaw Cygler
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
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37
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Naskar S, Hohl M, Tassinari M, Low HH. The structure and mechanism of the bacterial type II secretion system. Mol Microbiol 2020; 115:412-424. [PMID: 33283907 DOI: 10.1111/mmi.14664] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/03/2020] [Indexed: 12/17/2022]
Abstract
The type II secretion system (T2SS) is a multi-protein complex used by many bacteria to move substrates across their cell membrane. Substrates released into the environment serve as local and long-range effectors that promote nutrient acquisition, biofilm formation, and pathogenicity. In both animals and plants, the T2SS is increasingly recognized as a key driver of virulence. The T2SS spans the bacterial cell envelope and extrudes substrates through an outer membrane secretin channel using a pseudopilus. An inner membrane assembly platform and a cytoplasmic motor controls pseudopilus assembly. This microreview focuses on the structure and mechanism of the T2SS. Advances in cryo-electron microscopy are enabling increasingly elaborate sub-complexes to be resolved. However, key questions remain regarding the mechanism of pseudopilus extension and retraction, and how this is coupled with the choreography of the substrate moving through the secretion system. The T2SS is part of an ancient type IV filament superfamily that may have been present within the last universal common ancestor (LUCA). Overall, mechanistic principles that underlie T2SS function have implication for other closely related systems such as the type IV and tight adherence pilus systems.
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Affiliation(s)
- Souvik Naskar
- Department of Infectious Disease, Imperial College, London, UK
| | - Michael Hohl
- Department of Infectious Disease, Imperial College, London, UK
| | | | - Harry H Low
- Department of Infectious Disease, Imperial College, London, UK
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38
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Secrete or perish: The role of secretion systems in Xanthomonas biology. Comput Struct Biotechnol J 2020; 19:279-302. [PMID: 33425257 PMCID: PMC7777525 DOI: 10.1016/j.csbj.2020.12.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/13/2020] [Accepted: 12/13/2020] [Indexed: 12/22/2022] Open
Abstract
Bacteria of the Xanthomonas genus are mainly phytopathogens of a large variety of crops of economic importance worldwide. Xanthomonas spp. rely on an arsenal of protein effectors, toxins and adhesins to adapt to the environment, compete with other microorganisms and colonize plant hosts, often causing disease. These protein effectors are mainly delivered to their targets by the action of bacterial secretion systems, dedicated multiprotein complexes that translocate proteins to the extracellular environment or directly into eukaryotic and prokaryotic cells. Type I to type VI secretion systems have been identified in Xanthomonas genomes. Recent studies have unravelled the diverse roles played by the distinct types of secretion systems in adaptation and virulence in xanthomonads, unveiling new aspects of their biology. In addition, genome sequence information from a wide range of Xanthomonas species and pathovars have become available recently, uncovering a heterogeneous distribution of the distinct families of secretion systems within the genus. In this review, we describe the architecture and mode of action of bacterial type I to type VI secretion systems and the distribution and functions associated with these important nanoweapons within the Xanthomonas genus.
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39
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CryoEM map of Pseudomonas aeruginosa PilQ enables structural characterization of TsaP. Structure 2020; 29:457-466.e4. [PMID: 33338410 DOI: 10.1016/j.str.2020.11.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/22/2020] [Accepted: 11/24/2020] [Indexed: 01/22/2023]
Abstract
The type IV pilus machinery is a multi-protein complex that polymerizes and depolymerizes a pilus fiber used for attachment, twitching motility, phage adsorption, natural competence, protein secretion, and surface-sensing. An outer membrane secretin pore is required for passage of the pilus fiber out of the cell. Herein, the structure of the tetradecameric secretin, PilQ, from the Pseudomonas aeruginosa type IVa pilus system was determined to 4.3 Å and 4.4 Å resolution in the presence and absence of C7 symmetric spikes, respectively. The heptameric spikes were found to be two tandem C-terminal domains of TsaP. TsaP forms a belt around PilQ and while it is not essential for twitching motility, overexpression of TsaP triggers a signal cascade upstream of PilY1 leading to cyclic di-GMP up-regulation. These results resolve the identity of the spikes identified with Proteobacterial PilQ homologs and may reveal a new component of the surface-sensing cyclic di-GMP signal cascade.
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40
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Umrekar TR, Cohen E, Drobnič T, Gonzalez-Rodriguez N, Beeby M. CryoEM of bacterial secretion systems: A primer for microbiologists. Mol Microbiol 2020; 115:366-382. [PMID: 33140482 DOI: 10.1111/mmi.14637] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022]
Abstract
"CryoEM" has come of age, enabling considerable structural insights into many facets of molecular biology. Here, we present a primer for microbiologists to understand the capabilities and limitations of two complementary cryoEM techniques for studying bacterial secretion systems. The first, single particle analysis, determines the structures of purified protein complexes to resolutions sufficient for molecular modeling, while the second, electron cryotomography and subtomogram averaging, tends to determine more modest resolution structures of protein complexes in intact cells. We illustrate these abilities with examples of insights provided into how secretion systems work by cryoEM, with a focus on type III secretion systems.
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Affiliation(s)
| | - Eli Cohen
- Department of Life Sciences, Imperial College London, London, UK
| | - Tina Drobnič
- Department of Life Sciences, Imperial College London, London, UK
| | | | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, UK
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41
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Conradi FD, Mullineaux CW, Wilde A. The Role of the Cyanobacterial Type IV Pilus Machinery in Finding and Maintaining a Favourable Environment. Life (Basel) 2020; 10:life10110252. [PMID: 33114175 PMCID: PMC7690835 DOI: 10.3390/life10110252] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/18/2020] [Accepted: 10/21/2020] [Indexed: 12/11/2022] Open
Abstract
Type IV pili (T4P) are proteinaceous filaments found on the cell surface of many prokaryotic organisms and convey twitching motility through their extension/retraction cycles, moving cells across surfaces. In cyanobacteria, twitching motility is the sole mode of motility properly characterised to date and is the means by which cells perform phototaxis, the movement towards and away from directional light sources. The wavelength and intensity of the light source determine the direction of movement and, sometimes in concert with nutrient conditions, act as signals for some cyanobacteria to form mucoid multicellular assemblages. Formation of such aggregates or flocs represents an acclimation strategy to unfavourable environmental conditions and stresses, such as harmful light conditions or predation. T4P are also involved in natural transformation by exogenous DNA, secretion processes, and in cellular adaptation and survival strategies, further cementing the role of cell surface appendages. In this way, cyanobacteria are finely tuned by external stimuli to either escape unfavourable environmental conditions via phototaxis, exchange genetic material, and to modify their surroundings to fit their needs by forming multicellular assemblies.
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Affiliation(s)
- Fabian D. Conradi
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK; (F.D.C.); (C.W.M.)
| | - Conrad W. Mullineaux
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK; (F.D.C.); (C.W.M.)
| | - Annegret Wilde
- Institute of Biology III, University of Freiburg, Schänzlestr. 1, 79104 Freiburg; Germany
- Correspondence:
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42
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Weaver SJ, Ortega DR, Sazinsky MH, Dalia TN, Dalia AB, Jensen GJ. CryoEM structure of the type IVa pilus secretin required for natural competence in Vibrio cholerae. Nat Commun 2020; 11:5080. [PMID: 33033258 PMCID: PMC7545093 DOI: 10.1038/s41467-020-18866-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 09/15/2020] [Indexed: 02/07/2023] Open
Abstract
Natural transformation is the process by which bacteria take up genetic material from their environment and integrate it into their genome by homologous recombination. It represents one mode of horizontal gene transfer and contributes to the spread of traits like antibiotic resistance. In Vibrio cholerae, a type IVa pilus (T4aP) is thought to facilitate natural transformation by extending from the cell surface, binding to exogenous DNA, and retracting to thread this DNA through the outer membrane secretin, PilQ. Here, we use a functional tagged allele of VcPilQ purified from native V. cholerae cells to determine the cryoEM structure of the VcPilQ secretin in amphipol to ~2.7 Å. We use bioinformatics to examine the domain architecture and gene neighborhood of T4aP secretins in Proteobacteria in comparison with VcPilQ. This structure highlights differences in the architecture of the T4aP secretin from the type II and type III secretion system secretins. Based on our cryoEM structure, we design a series of mutants to reversibly regulate VcPilQ gate dynamics. These experiments support the idea of VcPilQ as a potential druggable target and provide insight into the channel that DNA likely traverses to promote the spread of antibiotic resistance via horizontal gene transfer by natural transformation.
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Affiliation(s)
- Sara J Weaver
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA, 91125, USA.,Howard Hughes Medical Institute, David Geffen School of Medicine, Departments of Biological Chemistry and Physiology, University of California Los Angeles, 615 Charles E Young Drive South, Los Angeles, CA, 90095, USA
| | - Davi R Ortega
- Division of Biology and Biological Engineering and Howard Hughes Medical Institute, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA, 91125, USA
| | - Matthew H Sazinsky
- Department of Chemistry, Pomona College, 333N. College Way, Claremont, CA, 91711, USA
| | - Triana N Dalia
- Department of Biology, Indiana University, 107S. Indiana Avenue, Bloomington, IN, 47405, USA
| | - Ankur B Dalia
- Department of Biology, Indiana University, 107S. Indiana Avenue, Bloomington, IN, 47405, USA
| | - Grant J Jensen
- Division of Biology and Biological Engineering and Howard Hughes Medical Institute, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA, 91125, USA.
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43
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Perlaza-Jiménez L, Wu Q, Torres VVL, Zhang X, Li J, Rocker A, Lithgow T, Zhou T, Vijaykrishna D. Forensic genomics of a novel Klebsiella quasipneumoniae type from a neonatal intensive care unit in China reveals patterns of colonization, evolution and epidemiology. Microb Genom 2020; 6:mgen000433. [PMID: 32931409 PMCID: PMC7660260 DOI: 10.1099/mgen.0.000433] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 09/01/2020] [Indexed: 12/16/2022] Open
Abstract
During March 2017, a neonatal patient with severe diarrhoea subsequently developed septicaemia and died, with Klebsiella isolated as the causative microorganism. In keeping with infection control protocols, the coincident illness of an attending staff member and three other neonates with Klebsiella infection triggered an outbreak response, leading to microbiological assessment of isolates collected from the staff member and all 21 co-housed neonates. Multilocus sequence typing and genomic sequencing identified that the isolates from the 21 neonates were of a new Klebsiella sequence type, ST2727, and taxonomically belonged to K. quasipneumoniae subsp. similipneumoniae (formerly referred to as KpIIB). Genomic characterization showed that the isolated ST2727 strains had diverged from other K. quasipneumoniae subsp. similipneumoniae strains at least 90 years ago, whereas the neonatal samples were highly similar with a genomic divergence of 3.6 months. There was no relationship to the Klebsiella isolate from the staff member. This demonstrates that no transmission occurred from staff to patient or between patients. Rather, the data suggest that ST2727 colonized each neonate from a common hospital source. Sequence-based analysis of the genomes revealed several genes for antimicrobial resistance and some virulence features, but suggest that ST2727 is neither extremely-drug resistant nor hypervirulent. Our results highlight the clinical significance and genomic properties of ST2727 and urge genome-based measures be implemented for diagnostics and surveillance within hospital environments. Additionally, the present study demonstrates the need to scale the power of genomic analysis in retrospective studies where relatively few samples are available.
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Affiliation(s)
| | - Qing Wu
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, PR China
| | - Von Vergel L. Torres
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
| | - Xiaoxiao Zhang
- Women’s Hospital School of Medicine Zhejiang University, Hangzhou, PR China
| | - Jiahui Li
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, PR China
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
| | - Andrea Rocker
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
| | - Trevor Lithgow
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
| | - Tieli Zhou
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, PR China
| | - Dhanasekaran Vijaykrishna
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, PR China
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
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44
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Sheedlo MJ, Chung JM, Sawhney N, Durie CL, Cover TL, Ohi MD, Lacy DB. Cryo-EM reveals species-specific components within the Helicobacter pylori Cag type IV secretion system core complex. eLife 2020; 9:e59495. [PMID: 32876048 PMCID: PMC7511236 DOI: 10.7554/elife.59495] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/01/2020] [Indexed: 02/06/2023] Open
Abstract
The pathogenesis of Helicobacter pylori-associated gastric cancer is dependent on delivery of CagA into host cells through a type IV secretion system (T4SS). The H. pylori Cag T4SS includes a large membrane-spanning core complex containing five proteins, organized into an outer membrane cap (OMC), a periplasmic ring (PR) and a stalk. Here, we report cryo-EM reconstructions of a core complex lacking Cag3 and an improved map of the wild-type complex. We define the structures of two unique species-specific components (Cag3 and CagM) and show that Cag3 is structurally similar to CagT. Unexpectedly, components of the OMC are organized in a 1:1:2:2:5 molar ratio (CagY:CagX:CagT:CagM:Cag3). CagX and CagY are components of both the OMC and the PR and bridge the symmetry mismatch between these regions. These results reveal that assembly of the H. pylori T4SS core complex is dependent on incorporation of interwoven species-specific components.
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Affiliation(s)
- Michael J Sheedlo
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical CenterNashvilleUnited States
| | - Jeong Min Chung
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Neha Sawhney
- Department of Medicine, Vanderbilt University School of MedicineNashvilleUnited States
| | - Clarissa L Durie
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Timothy L Cover
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical CenterNashvilleUnited States
- Department of Medicine, Vanderbilt University School of MedicineNashvilleUnited States
- Veterans Affairs Tennessee Valley Healthcare SystemNashvilleUnited States
| | - Melanie D Ohi
- Life Sciences Institute, University of MichiganAnn ArborUnited States
- Department of Cell and Developmental Biology, University of MichiganAnn ArborUnited States
| | - D Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical CenterNashvilleUnited States
- Veterans Affairs Tennessee Valley Healthcare SystemNashvilleUnited States
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45
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Majewski DD, Okon M, Heinkel F, Robb CS, Vuckovic M, McIntosh LP, Strynadka NCJ. Characterization of the Pilotin-Secretin Complex from the Salmonella enterica Type III Secretion System Using Hybrid Structural Methods. Structure 2020; 29:125-138.e5. [PMID: 32877645 DOI: 10.1016/j.str.2020.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/21/2020] [Accepted: 08/11/2020] [Indexed: 12/01/2022]
Abstract
The type III secretion system (T3SS) is a multi-membrane-spanning protein channel used by Gram-negative pathogenic bacteria to secrete effectors directly into the host cell cytoplasm. In the many species reliant on the T3SS for pathogenicity, proper assembly of the outer membrane secretin pore depends on a diverse family of lipoproteins called pilotins. We present structural and biochemical data on the Salmonella enterica pilotin InvH and the S domain of its cognate secretin InvG. Characterization of InvH by X-ray crystallography revealed a dimerized, α-helical pilotin. Size-exclusion-coupled multi-angle light scattering and small-angle X-ray scattering provide supporting evidence for the formation of an InvH homodimer in solution. Structures of the InvH-InvG heterodimeric complex determined by X-ray crystallography and NMR spectroscopy indicate a predominantly hydrophobic interface. Knowledge of the interaction between InvH and InvG brings us closer to understanding the mechanisms by which pilotins assemble the secretin pore.
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Affiliation(s)
- Dorothy D Majewski
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Mark Okon
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, and Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
| | - Florian Heinkel
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, and Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
| | - Craig S Robb
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Marija Vuckovic
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Lawrence P McIntosh
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, and Department of Chemistry, University of British Columbia, Vancouver, BC, Canada.
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, University of British Columbia, Vancouver, BC, Canada.
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46
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Franco A, Rückert C, Blom J, Busche T, Reichert J, Schubert P, Goesmann A, Kalinowski J, Wilke T, Kämpfer P, Glaeser SP. High diversity of Vibrio spp. associated with different ecological niches in a marine aquaria system and description of Vibrio aquimaris sp. nov. Syst Appl Microbiol 2020; 43:126123. [PMID: 32847789 DOI: 10.1016/j.syapm.2020.126123] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/09/2020] [Accepted: 07/10/2020] [Indexed: 10/23/2022]
Abstract
The aim of the study was to characterise the diversity and niche-specific colonization of Vibrio spp. in a marine aquaria system by a cultivation-dependent approach. A total of 53 Vibrio spp. isolates were cultured from different ecological niches in a marine aquarium including microplastic (MP) and sandy sediment particles (12 weeks after added sterile to the system), detritus, and the surrounding aquarium water. Based on the 16S rRNA gene sequence phylogeny and multilocus sequence analysis (MLSA) the isolates were assigned to seven different phylotypes. Six phylotypes were identified by high probability to the species level. The highest phylotype diversity was cultured from detritus and water (six out of seven phylotypes), while only two phylotypes were cultured from MP and sediment particles. Genomic fingerprinting indicated an even higher genetic diversity of Vibrio spp. at the strain (genotype) level. Again, the highest diversity of genotypes was recovered from detritus and water while only few partially particle-type specific genotypes were cultured from MP and sediment particles. Phylotype V-2 formed an independent branch in the MLSA tree and could not be assigned to a described Vibrio species. Isolates of this phylotype showed highest 16S rRNA gene sequence similarity to type strains of Vibrio japonicus (98.5%) and Vibrio caribbeanicus (98.4%). A representative isolate, strain THAF100T, was characterised by a polyphasic taxonomic approach and Vibrio aquimaris sp. nov., with strain THAF100T (=DSM 109633T=LMG 31434T=CIP 111709T) as type strain, is proposed as novel species.
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Affiliation(s)
- Angel Franco
- Institut für Angewandte Mikrobiologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany; Corporation Center of Excellence in Marine Sciences-CEMarin, Carrera 21 # 35-53, Bogotá, Colombia
| | - Christian Rückert
- Technology Platform Genomics, Center for Biotechnology (CeBiTec), Universität Bielefeld, 33594 Bielefeld, Germany
| | - Jochen Blom
- Institute for Bioinformatics and Systems Biology, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Tobias Busche
- Technology Platform Genomics, Center for Biotechnology (CeBiTec), Universität Bielefeld, 33594 Bielefeld, Germany
| | - Jessica Reichert
- Corporation Center of Excellence in Marine Sciences-CEMarin, Carrera 21 # 35-53, Bogotá, Colombia; Institut für Tierökologie und Spezielle Zoologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Patrick Schubert
- Corporation Center of Excellence in Marine Sciences-CEMarin, Carrera 21 # 35-53, Bogotá, Colombia; Institut für Tierökologie und Spezielle Zoologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Alexander Goesmann
- Institute for Bioinformatics and Systems Biology, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Jörn Kalinowski
- Technology Platform Genomics, Center for Biotechnology (CeBiTec), Universität Bielefeld, 33594 Bielefeld, Germany
| | - Thomas Wilke
- Corporation Center of Excellence in Marine Sciences-CEMarin, Carrera 21 # 35-53, Bogotá, Colombia; Institut für Tierökologie und Spezielle Zoologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Peter Kämpfer
- Institut für Angewandte Mikrobiologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Stefanie P Glaeser
- Institut für Angewandte Mikrobiologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany; Corporation Center of Excellence in Marine Sciences-CEMarin, Carrera 21 # 35-53, Bogotá, Colombia.
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Silva YRDO, Contreras-Martel C, Macheboeuf P, Dessen A. Bacterial secretins: Mechanisms of assembly and membrane targeting. Protein Sci 2020; 29:893-904. [PMID: 32020694 DOI: 10.1002/pro.3835] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/25/2020] [Accepted: 01/28/2020] [Indexed: 12/20/2022]
Abstract
Secretion systems are employed by bacteria to transport macromolecules across membranes without compromising their integrities. Processes including virulence, colonization, and motility are highly dependent on the secretion of effector molecules toward the immediate cellular environment, and in some cases, into the host cytoplasm. In Type II and Type III secretion systems, as well as in Type IV pili, homomultimeric complexes known as secretins form large pores in the outer bacterial membrane, and the localization and assembly of such 1 MDa molecules often relies on pilotins or accessory proteins. Significant progress has been made toward understanding details of interactions between secretins and their partner proteins using approaches ranging from bacterial genetics to cryo electron microscopy. This review provides an overview of the mode of action of pilotins and accessory proteins for T2SS, T3SS, and T4PS secretins, highlighting recent near-atomic resolution cryo-EM secretin complex structures and underlining the importance of these interactions for secretin functionality.
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Affiliation(s)
- Yuri Rafael de Oliveira Silva
- Brazilian Biosciences National Laboratory (LNBio), CNPEM, Campinas, São Paulo, Brazil.,Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Carlos Contreras-Martel
- Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Pauline Macheboeuf
- Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Andréa Dessen
- Brazilian Biosciences National Laboratory (LNBio), CNPEM, Campinas, São Paulo, Brazil.,Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
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