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Grossman AS, Gell DA, Wu DG, Carper DL, Hettich RL, Goodrich-Blair H. Bacterial hemophilin homologs and their specific type eleven secretor proteins have conserved roles in heme capture and are diversifying as a family. J Bacteriol 2024; 206:e0044423. [PMID: 38506530 DOI: 10.1128/jb.00444-23] [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: 01/05/2024] [Accepted: 02/18/2024] [Indexed: 03/21/2024] Open
Abstract
Cellular life relies on enzymes that require metals, which must be acquired from extracellular sources. Bacteria utilize surface and secreted proteins to acquire such valuable nutrients from their environment. These include the cargo proteins of the type eleven secretion system (T11SS), which have been connected to host specificity, metal homeostasis, and nutritional immunity evasion. This Sec-dependent, Gram-negative secretion system is encoded by organisms throughout the phylum Proteobacteria, including human pathogens Neisseria meningitidis, Proteus mirabilis, Acinetobacter baumannii, and Haemophilus influenzae. Experimentally verified T11SS-dependent cargo include transferrin-binding protein B (TbpB), the hemophilin homologs heme receptor protein C (HrpC), hemophilin A (HphA), the immune evasion protein factor-H binding protein (fHbp), and the host symbiosis factor nematode intestinal localization protein C (NilC). Here, we examined the specificity of T11SS systems for their cognate cargo proteins using taxonomically distributed homolog pairs of T11SS and hemophilin cargo and explored the ligand binding ability of those hemophilin cargo homologs. In vivo expression in Escherichia coli of hemophilin homologs revealed that each is secreted in a specific manner by its cognate T11SS protein. Sequence analysis and structural modeling suggest that all hemophilin homologs share an N-terminal ligand-binding domain with the same topology as the ligand-binding domains of the Haemophilus haemolyticus heme binding protein (Hpl) and HphA. We term this signature feature of this group of proteins the hemophilin ligand-binding domain. Network analysis of hemophilin homologs revealed five subclusters and representatives from four of these showed variable heme-binding activities, which, combined with sequence-structure variation, suggests that hemophilins are diversifying in function.IMPORTANCEThe secreted protein hemophilin and its homologs contribute to the survival of several bacterial symbionts within their respective host environments. Here, we compared taxonomically diverse hemophilin homologs and their paired Type 11 secretion systems (T11SS) to determine if heme binding and T11SS secretion are conserved characteristics of this family. We establish the existence of divergent hemophilin sub-families and describe structural features that contribute to distinct ligand-binding behaviors. Furthermore, we demonstrate that T11SS are specific for their cognate hemophilin family cargo proteins. Our work establishes that hemophilin homolog-T11SS pairs are diverging from each other, potentially evolving into novel ligand acquisition systems that provide competitive benefits in host niches.
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Affiliation(s)
- Alex S Grossman
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
| | - David A Gell
- School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Derek G Wu
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
- Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware, USA
| | - Dana L Carper
- Bioscience Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Robert L Hettich
- Bioscience Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Heidi Goodrich-Blair
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
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2
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Croia L, Boscato Sopetto G, Zanella I, Caproni E, Gagliardi A, Tamburini S, König E, Benedet M, Di Lascio G, Corbellari R, Grandi A, Tomasi M, Grandi G. Immunogenicity of Escherichia coli Outer Membrane Vesicles: Elucidation of Humoral Responses against OMV-Associated Antigens. MEMBRANES 2023; 13:882. [PMID: 37999368 PMCID: PMC10673343 DOI: 10.3390/membranes13110882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/10/2023] [Accepted: 11/11/2023] [Indexed: 11/25/2023]
Abstract
Outer membrane vesicles (OMVs) produced by Gram-negative bacteria have emerged as a novel and flexible vaccine platform. OMVs can be decorated with foreign antigens and carry potent immunostimulatory components. Therefore, after their purification from the culture supernatant, they are ready to be formulated for vaccine use. It has been extensively demonstrated that immunization with engineered OMVs can elicit excellent antibody responses against the heterologous antigens. However, the definition of the conditions necessary to reach the optimal antibody titers still needs to be investigated. Here, we defined the protein concentrations required to induce antigen-specific antibodies, and the amount of antigen and OMVs necessary and sufficient to elicit saturating levels of antigen-specific antibodies. Since not all antigens can be expressed in OMVs, we also investigated the effectiveness of vaccines in which OMVs and purified antigens are mixed together without using any procedure for their physical association. Our data show that in most of the cases OMV-antigen mixtures are very effective in eliciting antigen-specific antibodies. This is probably due to the capacity of OMVs to "absorb" antigens, establishing sufficiently stable interactions that allow antigen-OMV co-presentation to the same antigen presenting cell. In those cases when antigen-OMV interaction is not sufficiently stable, the addition of alum to the formulation guarantees the elicitation of high titers of antigen-specific antibodies.
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Affiliation(s)
- Lorenzo Croia
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Giulia Boscato Sopetto
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Ilaria Zanella
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Elena Caproni
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Assunta Gagliardi
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Silvia Tamburini
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Enrico König
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Mattia Benedet
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Gabriele Di Lascio
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Riccardo Corbellari
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Alberto Grandi
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
- BiOMViS Srl, Via Fiorentina 1, 53100 Siena, Italy
| | - Michele Tomasi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
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3
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Tamburini S, Zhang Y, Gagliardi A, Di Lascio G, Caproni E, Benedet M, Tomasi M, Corbellari R, Zanella I, Croia L, Grandi G, Müller M, Grandi A. Bacterial Outer Membrane Vesicles as a Platform for the Development of a Broadly Protective Human Papillomavirus Vaccine Based on the Minor Capsid Protein L2. Vaccines (Basel) 2023; 11:1582. [PMID: 37896984 PMCID: PMC10611245 DOI: 10.3390/vaccines11101582] [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: 09/08/2023] [Revised: 09/27/2023] [Accepted: 10/08/2023] [Indexed: 10/29/2023] Open
Abstract
Human papillomaviruses (HPVs) are a large family of viruses with a capsid composed of the L1 and L2 proteins, which bind to receptors of the basal epithelial cells and promote virus entry. The majority of sexually active people become exposed to HPV and the virus is the most common cause of cervical cancer. Vaccines are available based on the L1 protein, which self-assembles and forms virus-like particles (VLPs) when expressed in yeast and insect cells. Although very effective, these vaccines are HPV type-restricted and their costs limit broad vaccination campaigns. Recently, vaccine candidates based on the conserved L2 epitope from serotypes 16, 18, 31, 33, 35, 6, 51, and 59 were shown to elicit broadly neutralizing anti-HPV antibodies. In this study, we tested whether E. coli outer membrane vesicles (OMVs) could be successfully decorated with L2 polytopes and whether the engineered OMVs could induce neutralizing antibodies. OMVs represent an attractive vaccine platform owing to their intrinsic adjuvanticity and their low production costs. We show that strings of L2 epitopes could be efficiently expressed on the surface of the OMVs and a polypeptide composed of the L2 epitopes from serotypes 18, 33, 35, and 59 provided a broad cross-protective activity against a large panel of HPV serotypes as determined using pseudovirus neutralization assay. Considering the simplicity of the OMV production process, our work provides a highly effective and inexpensive solution to produce universal anti-HPV vaccines.
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Affiliation(s)
- Silvia Tamburini
- Department of Cellular, Computation and Integrative of Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (S.T.); (M.T.); (R.C.); (I.Z.); (L.C.)
| | - Yueru Zhang
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120 Heidelberg, Germany; (Y.Z.); (M.M.)
| | - Assunta Gagliardi
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (A.G.); (G.D.L.); (E.C.); (M.B.); (A.G.)
| | - Gabriele Di Lascio
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (A.G.); (G.D.L.); (E.C.); (M.B.); (A.G.)
| | - Elena Caproni
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (A.G.); (G.D.L.); (E.C.); (M.B.); (A.G.)
| | - Mattia Benedet
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (A.G.); (G.D.L.); (E.C.); (M.B.); (A.G.)
| | - Michele Tomasi
- Department of Cellular, Computation and Integrative of Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (S.T.); (M.T.); (R.C.); (I.Z.); (L.C.)
| | - Riccardo Corbellari
- Department of Cellular, Computation and Integrative of Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (S.T.); (M.T.); (R.C.); (I.Z.); (L.C.)
| | - Ilaria Zanella
- Department of Cellular, Computation and Integrative of Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (S.T.); (M.T.); (R.C.); (I.Z.); (L.C.)
| | - Lorenzo Croia
- Department of Cellular, Computation and Integrative of Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (S.T.); (M.T.); (R.C.); (I.Z.); (L.C.)
| | - Guido Grandi
- Department of Cellular, Computation and Integrative of Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (S.T.); (M.T.); (R.C.); (I.Z.); (L.C.)
| | - Martin Müller
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120 Heidelberg, Germany; (Y.Z.); (M.M.)
| | - Alberto Grandi
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (A.G.); (G.D.L.); (E.C.); (M.B.); (A.G.)
- BiOMViS Srl, Via Fiorentina 1, 53100 Siena, Italy
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4
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Huynh DT, Jong WSP, Oudejans MAH, van den Berg van Saparoea HB, Luirink J, van Ulsen P. Heterologous Display of Chlamydia trachomatis PmpD Passenger at the Surface of Salmonella OMVs. MEMBRANES 2023; 13:366. [PMID: 37103793 PMCID: PMC10145130 DOI: 10.3390/membranes13040366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 06/19/2023]
Abstract
Chlamydia trachomatis is the bacterial pathogen that causes most cases of sexually transmitted diseases annually. To combat the global spread of asymptomatic infection, development of effective (mucosal) vaccines that offer both systemic and local immune responses is considered a high priority. In this study, we explored the expression of C. trachomatis full-length (FL) PmpD, as well as truncated PmpD passenger constructs fused to a "display" autotransporter (AT) hemoglobin protease (HbpD) and studied their inclusion into outer membrane vesicles (OMVs) of Escherichia coli and Salmonella Typhimurium. OMVs are considered safe vaccine vectors well-suited for mucosal delivery. By using E. coli AT HbpD-fusions of chimeric constructs we improved surface display and successfully generated Salmonella OMVs decorated with a secreted and immunogenic PmpD passenger fragment (aa68-629) to 13% of the total protein content. Next, we investigated whether a similar chimeric surface display strategy could be applied to other AT antigens, i.e., secreted fragments of Prn (aa35-350) of Bordetella pertussis and VacA (aa65-377) of Helicobacter pylori. The data provided information on the complexity of heterologous expression of AT antigens at the OMV surface and suggested that optimal expression strategies should be developed on an antigen-to-antigen basis.
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Affiliation(s)
- Dung T. Huynh
- Abera Bioscience AB, 750 26 Uppsala, Sweden
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | | | - Manon A. H. Oudejans
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | | | - Joen Luirink
- Abera Bioscience AB, 750 26 Uppsala, Sweden
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | - Peter van Ulsen
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
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5
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The effects of different thermal and chemical stresses on release of outer membrane vesicles (OMVs) by ClearColi™. Arch Microbiol 2022; 204:714. [DOI: 10.1007/s00203-022-03287-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 10/03/2022] [Accepted: 10/17/2022] [Indexed: 11/19/2022]
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6
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Tomasi M, Caproni E, Benedet M, Zanella I, Giorgetta S, Dalsass M, König E, Gagliardi A, Fantappiè L, Berti A, Tamburini S, Croia L, Di Lascio G, Bellini E, Valensin S, Licata G, Sebastiani G, Dotta F, Armanini F, Cumbo F, Asnicar F, Blanco-Míguez A, Ruggiero E, Segata N, Grandi G, Grandi A. Outer Membrane Vesicles From The Gut Microbiome Contribute to Tumor Immunity by Eliciting Cross-Reactive T Cells. Front Oncol 2022; 12:912639. [PMID: 35847919 PMCID: PMC9281500 DOI: 10.3389/fonc.2022.912639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/20/2022] [Indexed: 12/03/2022] Open
Abstract
A growing body of evidence supports the notion that the gut microbiome plays an important role in cancer immunity. However, the underpinning mechanisms remain to be fully elucidated. One attractive hypothesis envisages that among the T cells elicited by the plethora of microbiome proteins a few exist that incidentally recognize neo-epitopes arising from cancer mutations (“molecular mimicry (MM)” hypothesis). To support MM, the human probiotic Escherichia coli Nissle was engineered with the SIINFEKL epitope (OVA-E.coli Nissle) and orally administered to C57BL/6 mice. The treatment with OVA-E.coli Nissle, but not with wild type E. coli Nissle, induced OVA-specific CD8+ T cells and inhibited the growth of tumors in mice challenged with B16F10 melanoma cells expressing OVA. The microbiome shotgun sequencing and the sequencing of TCRs from T cells recovered from both lamina propria and tumors provide evidence that the main mechanism of tumor inhibition is mediated by the elicitation at the intestinal site of cross-reacting T cells, which subsequently reach the tumor environment. Importantly, the administration of Outer Membrane Vesicles (OMVs) from engineered E. coli Nissle, as well as from E. coli BL21(DE3)ΔompA, carrying cancer-specific T cell epitopes also elicited epitope-specific T cells in the intestine and inhibited tumor growth. Overall, our data strengthen the important role of MM in tumor immunity and assign a novel function of OMVs in host-pathogen interaction. Moreover, our results pave the way to the exploitation of probiotics and OMVs engineered with tumor specific-antigens as personalized mucosal cancer vaccines.
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Affiliation(s)
- Michele Tomasi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Elena Caproni
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Mattia Benedet
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
- Toscana Life Sciences Foundation, Siena, Italy
| | - Ilaria Zanella
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Sebastiano Giorgetta
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Mattia Dalsass
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Enrico König
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
- Toscana Life Sciences Foundation, Siena, Italy
| | | | | | - Alvise Berti
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Silvia Tamburini
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Lorenzo Croia
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Gabriele Di Lascio
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | | | | | - Giada Licata
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto Di Mario, c/o Toscana Life Sciences Foundation, Siena, Italy
| | - Guido Sebastiani
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto Di Mario, c/o Toscana Life Sciences Foundation, Siena, Italy
| | - Francesco Dotta
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto Di Mario, c/o Toscana Life Sciences Foundation, Siena, Italy
- Tuscany Centre for Precision Medicine (CReMeP), Siena, Italy
| | - Federica Armanini
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Fabio Cumbo
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Francesco Asnicar
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Aitor Blanco-Míguez
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Eliana Ruggiero
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCSS) Ospedale San Raffaele, Milan, Italy
| | - Nicola Segata
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
- *Correspondence: Guido Grandi, ; Alberto Grandi,
| | - Alberto Grandi
- Toscana Life Sciences Foundation, Siena, Italy
- BiOMViS Srl, Siena, Italy
- *Correspondence: Guido Grandi, ; Alberto Grandi,
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7
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Grossman AS, Escobar CA, Mans EJ, Mucci NC, Mauer TJ, Jones KA, Moore CC, Abraham PE, Hettich RL, Schneider L, Campagna SR, Forest KT, Goodrich-Blair H. A Surface Exposed, Two-Domain Lipoprotein Cargo of a Type XI Secretion System Promotes Colonization of Host Intestinal Epithelia Expressing Glycans. Front Microbiol 2022; 13:800366. [PMID: 35572647 PMCID: PMC9100927 DOI: 10.3389/fmicb.2022.800366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/07/2022] [Indexed: 11/17/2022] Open
Abstract
The only known required component of the newly described Type XI secretion system (TXISS) is an outer membrane protein (OMP) of the DUF560 family. TXISSOMPs are broadly distributed across proteobacteria, but properties of the cargo proteins they secrete are largely unexplored. We report biophysical, histochemical, and phenotypic evidence that Xenorhabdus nematophila NilC is surface exposed. Biophysical data and structure predictions indicate that NilC is a two-domain protein with a C-terminal, 8-stranded β-barrel. This structure has been noted as a common feature of TXISS effectors and may be important for interactions with the TXISSOMP. The NilC N-terminal domain is more enigmatic, but our results indicate it is ordered and forms a β-sheet structure, and bioinformatics suggest structural similarities to carbohydrate-binding proteins. X. nematophila NilC and its presumptive TXISSOMP partner NilB are required for colonizing the anterior intestine of Steinernema carpocapsae nematodes: the receptacle of free-living, infective juveniles and the anterior intestinal cecum (AIC) in juveniles and adults. We show that, in adult nematodes, the AIC expresses a Wheat Germ Agglutinin (WGA)-reactive material, indicating the presence of N-acetylglucosamine or N-acetylneuraminic acid sugars on the AIC surface. A role for this material in colonization is supported by the fact that exogenous addition of WGA can inhibit AIC colonization by X. nematophila. Conversely, the addition of exogenous purified NilC increases the frequency with which X. nematophila is observed at the AIC, demonstrating that abundant extracellular NilC can enhance colonization. NilC may facilitate X. nematophila adherence to the nematode intestinal surface by binding to host glycans, it might support X. nematophila nutrition by cleaving sugars from the host surface, or it might help protect X. nematophila from nematode host immunity. Proteomic and metabolomic analyses of wild type X. nematophila compared to those lacking nilB and nilC revealed differences in cell wall and secreted polysaccharide metabolic pathways. Additionally, purified NilC is capable of binding peptidoglycan, suggesting that periplasmic NilC may interact with the bacterial cell wall. Overall, these findings support a model that NilB-regulated surface exposure of NilC mediates interactions between X. nematophila and host surface glycans during colonization. This is a previously unknown function for a TXISS.
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Affiliation(s)
- Alex S. Grossman
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Cristian A. Escobar
- Department of Bacteriology, The University of Wisconsin–Madison, Madison, WI, United States
| | - Erin J. Mans
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Nicholas C. Mucci
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Terra J. Mauer
- Department of Bacteriology, The University of Wisconsin–Madison, Madison, WI, United States
| | - Katarina A. Jones
- Department of Chemistry, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Cameron C. Moore
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Paul E. Abraham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Robert L. Hettich
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Liesel Schneider
- Department of Animal Sciences, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Shawn R. Campagna
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
- Biological and Small Molecule Mass Spectrometry Core, The University of Tennessee, Knoxville, Knoxville, TN, United States
- The University of Tennessee Oak Ridge Innovation Institute, Knoxville, TN, United States
| | - Katrina T. Forest
- Department of Bacteriology, The University of Wisconsin–Madison, Madison, WI, United States
- Katrina T. Forest,
| | - Heidi Goodrich-Blair
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
- Department of Bacteriology, The University of Wisconsin–Madison, Madison, WI, United States
- *Correspondence: Heidi Goodrich-Blair,
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8
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König E, Gagliardi A, Riedmiller I, Andretta C, Tomasi M, Irene C, Frattini L, Zanella I, Berti F, Grandi A, Caproni E, Fantappiè L, Grandi G. Multi-Antigen Outer Membrane Vesicle Engineering to Develop Polyvalent Vaccines: The Staphylococcus aureus Case. Front Immunol 2021; 12:752168. [PMID: 34819933 PMCID: PMC8606680 DOI: 10.3389/fimmu.2021.752168] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/14/2021] [Indexed: 11/13/2022] Open
Abstract
Modification of surface antigens and differential expression of virulence factors are frequent strategies pathogens adopt to escape the host immune system. These escape mechanisms make pathogens a "moving target" for our immune system and represent a challenge for the development of vaccines, which require more than one antigen to be efficacious. Therefore, the availability of strategies, which simplify vaccine design, is highly desirable. Bacterial Outer Membrane Vesicles (OMVs) are a promising vaccine platform for their built-in adjuvanticity, ease of purification and flexibility to be engineered with foreign proteins. However, data on if and how OMVs can be engineered with multiple antigens is limited. In this work, we report a multi-antigen expression strategy based on the co-expression of two chimeras, each constituted by head-to-tail fusions of immunogenic proteins, in the same OMV-producing strain. We tested the strategy to develop a vaccine against Staphylococcus aureus, a Gram-positive human pathogen responsible for a large number of community and hospital-acquired diseases. Here we describe an OMV-based vaccine in which four S. aureus virulent factors, ClfAY338A, LukE, SpAKKAA and HlaH35L have been co-expressed in the same OMVs (CLSH-OMVsΔ60). The vaccine elicited antigen-specific antibodies with functional activity, as judged by their capacity to promote opsonophagocytosis and to inhibit Hla-mediated hemolysis, LukED-mediated leukocyte killing, and ClfA-mediated S. aureus binding to fibrinogen. Mice vaccinated with CLSH-OMVsΔ60 were robustly protected from S. aureus challenge in the skin, sepsis and kidney abscess models. This study not only describes a generalized approach to develop easy-to-produce and inexpensive multi-component vaccines, but also proposes a new tetravalent vaccine candidate ready to move to development.
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Affiliation(s)
- Enrico König
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | | | - Ilary Riedmiller
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Chiara Andretta
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Michele Tomasi
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Carmela Irene
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Luca Frattini
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Ilaria Zanella
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Francesco Berti
- Technical Research and Development, GlaxoSmithKline Vaccines, Siena, Italy
| | - Alberto Grandi
- ERC Vaccibiome Unit, Toscana Life Sciences Foundation, Siena, Italy.,Infectious Diseases and Cancer Immunotherapy Unit, BiOMViS Srl, Siena, Italy
| | - Elena Caproni
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - Laura Fantappiè
- ERC Vaccibiome Unit, Toscana Life Sciences Foundation, Siena, Italy
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
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9
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Tomasi M, Dalsass M, Beghini F, Zanella I, Caproni E, Fantappiè L, Gagliardi A, Irene C, König E, Frattini L, Masetti G, Isaac SJ, Armanini F, Cumbo F, Blanco-Míguez A, Grandi A, Segata N, Grandi G. Commensal Bifidobacterium Strains Enhance the Efficacy of Neo-Epitope Based Cancer Vaccines. Vaccines (Basel) 2021; 9:vaccines9111356. [PMID: 34835287 PMCID: PMC8619961 DOI: 10.3390/vaccines9111356] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 12/25/2022] Open
Abstract
A large body of data both in animals and humans demonstrates that the gut microbiome plays a fundamental role in cancer immunity and in determining the efficacy of cancer immunotherapy. In this work, we have investigated whether and to what extent the gut microbiome can influence the antitumor activity of neo-epitope-based cancer vaccines in a BALB/c-CT26 cancer mouse model. Similarly to that observed in the C57BL/6-B16 model, Bifidobacterium administration per se has a beneficial effect on CT26 tumor inhibition. Furthermore, the combination of Bifidobacterium administration and vaccination resulted in a protection which was superior to vaccination alone and to Bifidobacterium administration alone, and correlated with an increase in the frequency of vaccine-specific T cells. The gut microbiome analysis by 16S rRNA gene sequencing and shotgun metagenomics showed that tumor challenge rapidly altered the microbiome population, with Muribaculaceae being enriched and Lachnospiraceae being reduced. Over time, the population of Muribaculaceae progressively reduced while the Lachnospiraceae population increased—a trend that appeared to be retarded by the oral administration of Bifidobacterium. Interestingly, in some Bacteroidales, Prevotella and Muribaculacee species we identified sequences highly homologous to immunogenic neo-epitopes of CT26 cells, supporting the possible role of “molecular mimicry” in anticancer immunity. Our data strengthen the importance of the microbiome in cancer immunity and suggests a microbiome-based strategy to potentiate neo-epitope-based cancer vaccines.
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Affiliation(s)
- Michele Tomasi
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Mattia Dalsass
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Francesco Beghini
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Ilaria Zanella
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Elena Caproni
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Laura Fantappiè
- Toscana Life Sciences, 53100 Siena, Italy; (L.F.); (A.G.); (A.G.)
| | | | - Carmela Irene
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Enrico König
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Luca Frattini
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Giulia Masetti
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Samine Jessica Isaac
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Federica Armanini
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Fabio Cumbo
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Aitor Blanco-Míguez
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Alberto Grandi
- Toscana Life Sciences, 53100 Siena, Italy; (L.F.); (A.G.); (A.G.)
- BiOMViS Srl, Via Fiorentina 1, 53100 Siena, Italy
| | - Nicola Segata
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology, University of Trento, 38123 Trento, Italy; (M.T.); (M.D.); (F.B.); (I.Z.); (E.C.); (C.I.); (E.K.); (L.F.); (G.M.); (S.J.I.); (F.A.); (F.C.); (A.B.-M.); (N.S.)
- Correspondence:
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10
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Grossman AS, Mauer TJ, Forest KT, Goodrich-Blair H. A Widespread Bacterial Secretion System with Diverse Substrates. mBio 2021; 12:e0195621. [PMID: 34399622 PMCID: PMC8406197 DOI: 10.1128/mbio.01956-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 07/09/2021] [Indexed: 01/26/2023] Open
Abstract
In host-associated bacteria, surface and secreted proteins mediate acquisition of nutrients, interactions with host cells, and specificity of tissue localization. In Gram-negative bacteria, the mechanism by which many proteins cross and/or become tethered to the outer membrane remains unclear. The domain of unknown function 560 (DUF560) occurs in outer membrane proteins throughout Proteobacteria and has been implicated in host-bacterium interactions and lipoprotein surface exposure. We used sequence similarity networking to reveal three subfamilies of DUF560 homologs. One subfamily includes those DUF560 proteins experimentally characterized thus far: NilB, a host range determinant of the nematode-mutualist Xenorhabdus nematophila, and the surface lipoprotein assembly modulators Slam1 and Slam2, which facilitate lipoprotein surface exposure in Neisseria meningitidis (Y. Hooda, C. C. Lai, A. Judd, C. M. Buckwalter, et al., Nat Microbiol 1:16009, 2016, https://doi.org/10.1038/nmicrobiol.2016.9; Y. Hooda, C. C. L. Lai, T. F. Moraes, Front Cell Infect Microbiol 7:207, 2017, https://doi.org/10.3389/fcimb.2017.00207). We show that DUF560 proteins from a second subfamily facilitate secretion of soluble, nonlipidated proteins across the outer membrane. Using in silico analysis, we demonstrate that DUF560 gene complement correlates with bacterial environment at a macro level and host association at a species level. The DUF560 protein superfamily represents a newly characterized Gram-negative secretion system capable of lipoprotein surface exposure and soluble protein secretion with conserved roles in facilitating symbiosis. In light of these data, we propose that it be titled the type 11 secretion system (TXISS). IMPORTANCE The microbial constituency of a host-associated microbiome emerges from a complex physical and chemical interplay of microbial colonization factors, host surface conditions, and host immunological responses. To fill unique niches within a host, bacteria encode surface and secreted proteins that enable interactions with and responses to the host and co-occurring microbes. Bioinformatic predictions of putative bacterial colonization factor localization and function facilitate hypotheses about the potential of bacteria to engage in pathogenic, mutualistic, or commensal activities. This study uses publicly available genome sequence data alongside experimental results from Xenorhabdus nematophila to demonstrate a role for DUF560 family proteins in secretion of bacterial effectors of host interactions. Our research delineates a broadly distributed family of proteins and enables more accurate predictions of the localization of colonization factors throughout Proteobacteria.
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Affiliation(s)
- Alex S. Grossman
- University of Tennessee—Knoxville, Department of Microbiology, Knoxville, Tennessee, USA
| | - Terra J. Mauer
- University of Wisconsin—Madison, Department of Bacteriology, Madison, Wisconsin, USA
| | - Katrina T. Forest
- University of Wisconsin—Madison, Department of Bacteriology, Madison, Wisconsin, USA
| | - Heidi Goodrich-Blair
- University of Tennessee—Knoxville, Department of Microbiology, Knoxville, Tennessee, USA
- University of Wisconsin—Madison, Department of Bacteriology, Madison, Wisconsin, USA
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11
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Sharaf NG, Shahgholi M, Kim E, Lai JY, VanderVelde DG, Lee AT, Rees DC. Characterization of the ABC methionine transporter from Neisseria meningitidis reveals that lipidated MetQ is required for interaction. eLife 2021; 10:69742. [PMID: 34409939 PMCID: PMC8416018 DOI: 10.7554/elife.69742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 08/18/2021] [Indexed: 01/05/2023] Open
Abstract
NmMetQ is a substrate-binding protein (SBP) from Neisseria meningitidis that has been identified as a surface-exposed candidate antigen for meningococcal vaccines. However, this location for NmMetQ challenges the prevailing view that SBPs in Gram-negative bacteria are localized to the periplasmic space to promote interaction with their cognate ABC transporter embedded in the bacterial inner membrane. To elucidate the roles of NmMetQ, we characterized NmMetQ with and without its cognate ABC transporter (NmMetNI). Here, we show that NmMetQ is a lipoprotein (lipo-NmMetQ) that binds multiple methionine analogs and stimulates the ATPase activity of NmMetNI. Using single-particle electron cryo-microscopy, we determined the structures of NmMetNI in the presence and absence of lipo-NmMetQ. Based on our data, we propose that NmMetQ tethers to membranes via a lipid anchor and has dual function and localization, playing a role in NmMetNI-mediated transport at the inner membrane and moonlighting on the bacterial surface.
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Affiliation(s)
- Naima G Sharaf
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
| | - Mona Shahgholi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| | - Esther Kim
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| | - Jeffrey Y Lai
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
| | - David G VanderVelde
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| | - Allen T Lee
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
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12
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Zanella I, König E, Tomasi M, Gagliardi A, Frattini L, Fantappiè L, Irene C, Zerbini F, Caproni E, Isaac SJ, Grigolato M, Corbellari R, Valensin S, Ferlenghi I, Giusti F, Bini L, Ashhab Y, Grandi A, Grandi G. Proteome-minimized outer membrane vesicles from Escherichia coli as a generalized vaccine platform. J Extracell Vesicles 2021; 10:e12066. [PMID: 33643549 PMCID: PMC7886703 DOI: 10.1002/jev2.12066] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 12/26/2020] [Accepted: 01/13/2021] [Indexed: 02/01/2023] Open
Abstract
Because of their potent adjuvanticity, ease of manipulation and simplicity of production Gram‐negative Outer Membrane Vesicles OMVs have the potential to become a highly effective vaccine platform. However, some optimization is required, including the reduction of the number of endogenous proteins, the increase of the loading capacity with respect to heterologous antigens, the enhancement of productivity in terms of number of vesicles per culture volume. In this work we describe the use of Synthetic Biology to create Escherichia coli BL21(DE3)Δ60, a strain releasing OMVs (OMVsΔ60) deprived of 59 endogenous proteins. The strain produces large quantities of vesicles (> 40 mg/L under laboratory conditions), which can accommodate recombinant proteins to a level ranging from 5% to 30% of total OMV proteins. Moreover, also thanks to the absence of immune responses toward the inactivated endogenous proteins, OMVsΔ60 decorated with heterologous antigens/epitopes elicit elevated antigens/epitopes‐specific antibody titers and high frequencies of epitope‐specific IFN‐γ‐producing CD8+ T cells. Altogether, we believe that E. coli BL21(DE3)Δ60 have the potential to become a workhorse factory for novel OMV‐based vaccines.
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Affiliation(s)
- Ilaria Zanella
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Enrico König
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Michele Tomasi
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Assunta Gagliardi
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Luca Frattini
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | | | - Carmela Irene
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Francesca Zerbini
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Elena Caproni
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Samine J Isaac
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Martina Grigolato
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | - Riccardo Corbellari
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
| | | | | | | | - Luca Bini
- Department of Life Sciences Functional Proteomics Laboratories University of Siena Siena Italy
| | - Yaqoub Ashhab
- Palestine-Korea Biotechnology Center Palestine Polytechnic University Hebron Palestine
| | - Alberto Grandi
- Toscana Life Sciences Foundation Siena Italy.,BiOMViS Srl Siena Italy
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology (CIBIO) Laboratory of Synthetic and Structural Vaccinology University of Trento Trento Italy
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13
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Nicchi S, Giuliani M, Giusti F, Pancotto L, Maione D, Delany I, Galeotti CL, Brettoni C. Decorating the surface of Escherichia coli with bacterial lipoproteins: a comparative analysis of different display systems. Microb Cell Fact 2021; 20:33. [PMID: 33531008 PMCID: PMC7853708 DOI: 10.1186/s12934-021-01528-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/23/2021] [Indexed: 11/10/2022] Open
Abstract
Background The display of recombinant proteins on cell surfaces has a plethora of applications including vaccine development, screening of peptide libraries, whole-cell biocatalysts and biosensor development for diagnostic, industrial or environmental purposes. In the last decades, a wide variety of surface display systems have been developed for the exposure of recombinant proteins on the surface of Escherichia coli, such as autotransporters and outer membrane proteins. Results In this study, we assess three approaches for the surface display of a panel of heterologous and homologous mature lipoproteins in E. coli: four from Neisseria meningitidis and four from the host strain that are known to be localised in the inner leaflet of the outer membrane. Constructs were made carrying the sequences coding for eight mature lipoproteins, each fused to the delivery portion of three different systems: the autotransporter adhesin involved in diffuse adherence-I (AIDA-I) from enteropathogenic E. coli, the Lpp’OmpA chimaera and a truncated form of the ice nucleation protein (INP), InaK-NC (N-terminal domain fused with C-terminal one) from Pseudomonas syringae. In contrast to what was observed for the INP constructs, when fused to the AIDA-I or Lpp’OmpA, most of the mature lipoproteins were displayed on the bacterial surface both at 37 and 25 °C as demonstrated by FACS analysis, confocal and transmission electron microscopy. Conclusions To our knowledge this is the first study that compares surface display systems using a number of passenger proteins. We have shown that the experimental conditions, including the choice of the carrier protein and the growth temperature, play an important role in the translocation of mature lipoproteins onto the bacterial surface. Despite all the optimization steps performed with the InaK-NC anchor motif, surface exposure of the passenger proteins used in this study was not achieved. For our experimental conditions, Lpp’OmpA chimaera has proved to be an efficient surface display system for the homologous passenger proteins although cell lysis and phenotype heterogeneity were observed. Finally, AIDA-I was found to be the best surface display system for mature lipoproteins (especially heterologous ones) in the E. coli host strain with no inhibition of growth and only limited phenotype heterogeneity.
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Affiliation(s)
- Sonia Nicchi
- GSK, via Fiorentina 1, 53100, Siena, Italy.,Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
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14
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Knoke LR, Abad Herrera S, Götz K, Justesen BH, Günther Pomorski T, Fritz C, Schäkermann S, Bandow JE, Aktas M. Agrobacterium tumefaciens Small Lipoprotein Atu8019 Is Involved in Selective Outer Membrane Vesicle (OMV) Docking to Bacterial Cells. Front Microbiol 2020; 11:1228. [PMID: 32582124 PMCID: PMC7296081 DOI: 10.3389/fmicb.2020.01228] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 05/14/2020] [Indexed: 12/02/2022] Open
Abstract
Outer membrane vesicles (OMVs), released from Gram-negative bacteria, have been attributed to intra- and interspecies communication and pathogenicity in diverse bacteria. OMVs carry various components including genetic material, toxins, signaling molecules, or proteins. Although the molecular mechanism(s) of cargo delivery is not fully understood, recent studies showed that transfer of the OMV content to surrounding cells is mediated by selective interactions. Here, we show that the phytopathogen Agrobacterium tumefaciens, the causative agent of crown gall disease, releases OMVs, which attach to the cell surface of various Gram-negative bacteria. The OMVs contain the conserved small lipoprotein Atu8019. An atu8019-deletion mutant produced wildtype-like amounts of OMVs with a subtle but reproducible reduction in cell-attachment. Otherwise, loss of atu8019 did not alter growth, susceptibility against cations or antibiotics, attachment to plant cells, virulence, motility, or biofilm formation. In contrast, overproduction of Atu8019 in A. tumefaciens triggered cell aggregation and biofilm formation. Localization studies revealed that Atu8019 is surface exposed in Agrobacterium cells and in OMVs supporting a role in cell adhesion. Purified Atu8019 protein reconstituted into liposomes interacted with model membranes and with the surface of several Gram-negative bacteria. Collectively, our data suggest that the small lipoprotein Atu8019 is involved in OMV docking to specific bacteria.
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Affiliation(s)
- Lisa Roxanne Knoke
- Faculty of Biology and Biotechnology, Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Sara Abad Herrera
- Faculty of Chemistry and Biochemistry, Department of Molecular Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Katrin Götz
- Faculty of Biology and Biotechnology, Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Bo Højen Justesen
- Faculty of Chemistry and Biochemistry, Department of Molecular Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Thomas Günther Pomorski
- Faculty of Chemistry and Biochemistry, Department of Molecular Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Christiane Fritz
- Faculty of Biology and Biotechnology, Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Sina Schäkermann
- Faculty of Biology and Biotechnology, Department of Applied Microbiology, Ruhr University Bochum, Bochum, Germany
| | - Julia Elisabeth Bandow
- Faculty of Biology and Biotechnology, Department of Applied Microbiology, Ruhr University Bochum, Bochum, Germany
| | - Meriyem Aktas
- Faculty of Biology and Biotechnology, Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
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15
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Notarangelo M, Ferrara D, Potrich C, Lunelli L, Vanzetti L, Provenzani A, Basso M, Quattrone A, D'Agostino VG. Rapid Nickel-based Isolation of Extracellular Vesicles from Different Biological Fluids. Bio Protoc 2020; 10:e3512. [PMID: 33654737 DOI: 10.21769/bioprotoc.3512] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 12/31/2022] Open
Abstract
Extracellular vesicles (EVs) are membranous structures that cells massively release in extracellular fluids. EVs are cargo of cellular components such as lipids, proteins, and nucleic acids that can work as a formidable source in liquid biopsy studies searching for disease biomarkers. We recently demonstrated that nickel-based isolation (NBI) is a valuable method for fast, efficient, and easy recovery of heterogeneous EVs from biological fluids. NBI exploits nickel cations to capture negatively charged vesicles. Then, a mix of balanced chelating agents elutes EVs while preserving their integrity and stability in solution. Here, we describe steps and quality controls to functionalize a matrix of agarose beads, obtain an efficient elution of EVs, and extract nucleic acids carried by them. We demonstrate the versatility of NBI method in isolating EVs from media of primary mouse astrocytes, from human blood, urine, and saliva processed in parallel, as well as outer membrane vesicles (OMVs) from cultured Gram-negative bacteria.
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Affiliation(s)
- Michela Notarangelo
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Deborah Ferrara
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Cristina Potrich
- Fondazione Bruno Kessler (FBK), Laboratory of Biomolecular Sequence and Structure Analysis for Health, and CNR-Institute of Biophysics, Trento, Italy
| | - Lorenzo Lunelli
- Fondazione Bruno Kessler (FBK), Laboratory of Biomolecular Sequence and Structure Analysis for Health, and CNR-Institute of Biophysics, Trento, Italy
| | - Lia Vanzetti
- Fondazione Bruno Kessler (FBK), Center for Materials and Microsystems, Trento, Italy
| | - Alessandro Provenzani
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Manuela Basso
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Alessandro Quattrone
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Vito G D'Agostino
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
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16
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Bacterial outer membrane vesicles engineered with lipidated antigens as a platform for Staphylococcus aureus vaccine. Proc Natl Acad Sci U S A 2019; 116:21780-21788. [PMID: 31591215 PMCID: PMC6815149 DOI: 10.1073/pnas.1905112116] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Bacterial outer membrane vesicles (OMVs) represent an interesting vaccine platform for their built-in adjuvanticity and simplicity of production process. Moreover, OMVs can be decorated with foreign antigens using different synthetic biology approaches. However, the optimal OMV engineering strategy, which should guarantee the OMV compartmentalization of most heterologous antigens in quantities high enough to elicit protective immune responses, remains to be validated. In this work we exploited the lipoprotein transport pathway to engineer OMVs with foreign proteins. Using 5 Staphylococcus aureus protective antigens expressed in Escherichia coli as fusions to a lipoprotein leader sequence, we demonstrated that all 5 antigens accumulated in the vesicular compartment at a concentration ranging from 5 to 20% of total OMV proteins, suggesting that antigen lipidation could be a universal approach for OMV manipulation. Engineered OMVs elicited high, saturating antigen-specific antibody titers when administered to mice in quantities as low as 0.2 μg/dose. Moreover, the expression of lipidated antigens in E. coli BL21(DE3)ΔompAΔmsbBΔpagP was shown to affect the lipopolysaccharide structure, with the result that the TLR4 agonist activity of OMVs was markedly reduced. These results, together with the potent protective activity of engineered OMVs observed in mice challenged with S. aureus Newman strain, makes the 5-combo-OMVs a promising vaccine candidate to be tested in clinics.
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Mishra S, Crowley PJ, Wright KR, Palmer SR, Walker AR, Datta S, Brady LJ. Membrane proteomic analysis reveals overlapping and independent functions of Streptococcus mutans Ffh, YidC1, and YidC2. Mol Oral Microbiol 2019; 34:131-152. [PMID: 31034136 DOI: 10.1111/omi.12261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/23/2019] [Accepted: 04/24/2019] [Indexed: 11/29/2022]
Abstract
A comparative proteomic analysis was utilized to evaluate similarities and differences in membrane samples derived from the cariogenic bacterium Streptococcus mutans, including the wild-type strain and four mutants devoid of protein translocation machinery components, specifically ∆ffh, ∆yidC1, ∆yidC2, or ∆ffh/yidC1. The purpose of this work was to determine the extent to which the encoded proteins operate individually or in concert with one another and to identify the potential substrates of the respective pathways. Ffh is the principal protein component of the signal recognition particle (SRP), while yidC1 and yidC2 are dual paralogs encoding members of the YidC/Oxa/Alb family of membrane-localized chaperone insertases. Our results suggest that the co-translational SRP pathway works in concert with either YidC1 or YidC2 specifically, or with no preference for paralog, in the insertion of most membrane-localized substrates. A few instances were identified in which the SRP pathway alone, or one of the YidCs alone, appeared to be most relevant. These data shed light on underlying reasons for differing phenotypic consequences of ffh, yidC1 or yidC2 deletion. Our data further suggest that many membrane proteins present in a ∆yidC2 background may be non-functional, that ∆yidC1 is better able to adapt physiologically to the loss of this paralog, that shared phenotypic properties of ∆ffh and ∆yidC2 mutants can stem from impacts on different proteins, and that independent binding to ribosomal proteins is not a primary functional activity of YidC2. Lastly, genomic mutations accumulate in a ∆yidC2 background coincident with phenotypic reversion, including an apparent W138R suppressor mutation within yidC1.
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Affiliation(s)
- Surabhi Mishra
- Department of Oral Biology, University of Florida, Gainesville, Florida
| | - Paula J Crowley
- Department of Oral Biology, University of Florida, Gainesville, Florida
| | - Katherine R Wright
- Division of Biosciences College of Dentistry, The Ohio State University, Columbus, Ohio
| | - Sara R Palmer
- Division of Biosciences College of Dentistry, The Ohio State University, Columbus, Ohio
| | | | - Susmita Datta
- Department of Biostatistics, College of Public Health & Health Professions College of Medicine, University of Florida, Gainesville, Florida
| | - L Jeannine Brady
- Department of Oral Biology, University of Florida, Gainesville, Florida
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18
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Abstract
The Lpp lipoprotein of Escherichia coli is the first identified protein with a covalently linked lipid. It is chemically bound by its C-terminus to murein (peptidoglycan) and inserts by the lipid at the N-terminus into the outer membrane. As the most abundant protein in E. coli (106 molecules per cell) it plays an important role for the integrity of the cell envelope. Lpp represents the type protein of a large variety of lipoproteins found in Gram-negative and Gram-positive bacteria and in archaea that have in common the lipid structure for anchoring the proteins to membranes but otherwise strongly vary in sequence, structure, and function. Predicted lipoproteins in known prokaryotic genomes comprise 2.7% of all proteins. Lipoproteins are modified by a unique phospholipid pathway and transferred from the cytoplasmic membrane into the outer membrane by a special system. They are involved in protein incorporation into the outer membrane, protein secretion across the cytoplasmic membrane, periplasm and outer membrane, signal transduction, conjugation, cell wall metabolism, antibiotic resistance, biofilm formation, and adhesion to host tissues. They are only found in bacteria and function as signal molecules for the innate immune system of vertebrates, where they cause inflammation and elicit innate and adaptive immune response through Toll-like receptors. This review discusses various aspects of Lpp and other lipoproteins of Gram-negative and Gram-positive bacteria and archaea.
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Affiliation(s)
- Volkmar Braun
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Max Planck Ring 5, 72076, Tübingen, Germany.
| | - Klaus Hantke
- IMIT, University of Tuebingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
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Grandi A, Fantappiè L, Irene C, Valensin S, Tomasi M, Stupia S, Corbellari R, Caproni E, Zanella I, Isaac SJ, Ganfini L, Frattini L, König E, Gagliardi A, Tavarini S, Sammicheli C, Parri M, Grandi G. Vaccination With a FAT1-Derived B Cell Epitope Combined With Tumor-Specific B and T Cell Epitopes Elicits Additive Protection in Cancer Mouse Models. Front Oncol 2018; 8:481. [PMID: 30416985 PMCID: PMC6212586 DOI: 10.3389/fonc.2018.00481] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/08/2018] [Indexed: 12/30/2022] Open
Abstract
Human FAT1 is overexpressed on the surface of most colorectal cancers (CRCs) and in particular a 25 amino acid sequence (D8) present in one of the 34 cadherin extracellular repeats carries the epitope recognized by mAb198.3, a monoclonal antibody which partially protects mice from the challenge with human CRC cell lines in xenograft mouse models. Here we present data in immune competent mice demonstrating the potential of the D8-FAT1 epitope as CRC cancer vaccine. We first demonstrated that the mouse homolog of D8-FAT1 (mD8-FAT1) is also expressed on the surface of CT26 and B16F10 murine cell lines. We then engineered bacterial outer membranes vesicles (OMVs) with mD8-FAT1 and we showed that immunization of BALB/c and C57bl6 mice with engineered OMVs elicited anti-mD8-FAT1 antibodies and partially protected mice from the challenge against CT26 and EGFRvIII-B16F10 cell lines, respectively. We also show that when combined with OMVs decorated with the EGFRvIII B cell epitope or with OMVs carrying five tumor-specific CD4+ T cells neoepitopes, mD8-FAT1 OMVs conferred robust protection against tumor challenge in C57bl6 and BALB/c mice, respectively. Considering that FAT1 is overexpressed in both KRAS+ and KRAS− CRCs, these data support the development of anti-CRC cancer vaccines in which the D8-FAT1 epitope is used in combination with other CRC-specific antigens, including mutation-derived neoepitopes.
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Donnarumma D, Maestri C, Giammarinaro PI, Capriotti L, Bartolini E, Veggi D, Petracca R, Scarselli M, Norais N. Native State Organization of Outer Membrane Porins Unraveled by HDx-MS. J Proteome Res 2018; 17:1794-1800. [PMID: 29619829 DOI: 10.1021/acs.jproteome.7b00830] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Hydrogen-deuterium exchange (HDx) associated with mass spectrometry (MS) is emerging as a powerful tool to provide conformational information about membrane proteins. Unfortunately, as for X-ray diffraction and NMR, HDx performed on reconstituted in vitro systems might not always reflect the in vivo environment. Outer-membrane vesicles naturally released by Escherichia coli were used to carry out analysis of native OmpF through HDx-MS. A new protocol compatible with HDx analysis that avoids hindrance from the lipid contents was setup. The extent of deuterium incorporation was in good agreement with the X-ray diffraction data of OmpF as the buried β-barrels incorporated a low amount of deuterium, whereas the internal loop L3 and the external loops incorporated a higher amount of deuterium. Moreover, the kinetics of incorporation clearly highlights that peptides segregate well in two distinct groups based exclusively on a trimeric organization of OmpF in the membrane: peptides presenting fast kinetics of labeling are facing the complex surrounding environment, whereas those presenting slow kinetics are located in the buried core of the trimer. The data show that HDx-MS applied to a complex biological system is able to reveal solvent accessibility and spatial arrangement of an integral outer-membrane protein complex.
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21
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Grandi A, Tomasi M, Zanella I, Ganfini L, Caproni E, Fantappiè L, Irene C, Frattini L, Isaac SJ, König E, Zerbini F, Tavarini S, Sammicheli C, Giusti F, Ferlenghi I, Parri M, Grandi G. Synergistic Protective Activity of Tumor-Specific Epitopes Engineered in Bacterial Outer Membrane Vesicles. Front Oncol 2017; 7:253. [PMID: 29164053 PMCID: PMC5681935 DOI: 10.3389/fonc.2017.00253] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/09/2017] [Indexed: 12/21/2022] Open
Abstract
Introduction Bacterial outer membrane vesicles (OMVs) are naturally produced by all Gram-negative bacteria and, thanks to their plasticity and unique adjuvanticity, are emerging as an attractive vaccine platform. To test the applicability of OMVs in cancer immunotherapy, we decorated them with either one or two protective epitopes present in the B16F10EGFRvIII cell line and tested the protective activity of OMV immunization in C57BL/6 mice challenged with B16F10EGFRvIII. Materials and methods The 14 amino acid B cell epitope of human epidermal growth factor receptor variant III (EGFRvIII) and the mutation-derived CD4+ T cell neo-epitope of kif18b gene (B16-M30) were used to decorate OMVs either alone or in combination. C57BL/6 were immunized with the OMVs and then challenged with B16F10EGFRvIII cells. Immunogenicity and protective activity was followed by measuring anti-EGFRvIII antibodies, M30-specific T cells, tumor-infiltrating cell population, and tumor growth. Results Immunization with engineered EGFRvIII-OMVs induced a strong inhibition of tumor growth after B16F10EGFRvIII challenge. Furthermore, mice immunized with engineered OMVs carrying both EGFRvIII and M30 epitopes were completely protected from tumor challenge. Immunization was accompanied by induction of high anti-EGFRvIII antibody titers, M30-specific T cells, and infiltration of CD4+ and CD8+ T cells at the tumor site. Conclusion OMVs can be decorated with tumor antigens and can elicit antigen-specific, protective antitumor responses in immunocompetent mice. The synergistic protective activity of multiple epitopes simultaneously administered with OMVs makes the OMV platform particularly attractive for cancer immunotherapy.
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Affiliation(s)
| | - Michele Tomasi
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Ilaria Zanella
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Luisa Ganfini
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Elena Caproni
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Laura Fantappiè
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Carmela Irene
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Luca Frattini
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Samine J Isaac
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Enrico König
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Francesca Zerbini
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | | | | | | | | | - Matteo Parri
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Guido Grandi
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
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