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Sirisaengtaksin N, O'Donoghue EJ, Jabbari S, Roe AJ, Krachler AM. Bacterial outer membrane vesicles provide an alternative pathway for trafficking of Escherichia coli O157 type III secreted effectors to epithelial cells. mSphere 2023; 8:e0052023. [PMID: 37929984 PMCID: PMC10732017 DOI: 10.1128/msphere.00520-23] [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: 09/18/2023] [Accepted: 10/03/2023] [Indexed: 11/07/2023] Open
Abstract
IMPORTANCE Bacteria can package protein cargo into nanosized membrane blebs that are shed from the bacterial membrane and released into the environment. Here, we report that a type of pathogenic bacteria called enterohemorrhagic Escherichia coli O157 (EHEC) uses their membrane blebs (outer membrane vesicles) to package components of their type 3 secretion system and send them into host cells, where they can manipulate host signaling pathways including those involved in infection response, such as immunity. Usually, EHEC use a needle-like apparatus to inject these components into host cells, but packaging them into membrane blebs that get taken up by host cells is another way of delivery that can bypass the need for a functioning injection system.
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Affiliation(s)
- Natalie Sirisaengtaksin
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Eloise J. O'Donoghue
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Sara Jabbari
- School of Mathematics, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Andrew J. Roe
- School of Infection and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Anne Marie Krachler
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
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2
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Zhao Z, Hu Y, Hu Y, White AP, Wang Y. Features and algorithms: facilitating investigation of secreted effectors in Gram-negative bacteria. Trends Microbiol 2023; 31:1162-1178. [PMID: 37349207 DOI: 10.1016/j.tim.2023.05.011] [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: 03/15/2023] [Revised: 05/22/2023] [Accepted: 05/22/2023] [Indexed: 06/24/2023]
Abstract
Gram-negative bacteria deliver effector proteins through type III, IV, or VI secretion systems (T3SSs, T4SSs, and T6SSs) into host cells, causing infections and diseases. In general, effector proteins for each of these distinct secretion systems lack homology and are difficult to identify. Sequence analysis has disclosed many common features, helping us to understand the evolution, function, and secretion mechanisms of the effectors. In combination with various algorithms, the known common features have facilitated accurate prediction of new effectors. Ensemblers or integrated pipelines achieve a better prediction of performance, which combines multiple computational models or modules with multidimensional features. Natural language processing (NLP) models also show the merits, which could enable discovery of novel features and, in turn, facilitate more precise effector prediction, extending our knowledge about each secretion mechanism.
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Affiliation(s)
- Ziyi Zhao
- Youth Innovation Team of Medical Bioinformatics, Shenzhen University Medical School, Shenzhen 518060, China
| | - Yixue Hu
- Youth Innovation Team of Medical Bioinformatics, Shenzhen University Medical School, Shenzhen 518060, China
| | - Yueming Hu
- Department of Bioinformatics, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Aaron P White
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Yejun Wang
- Youth Innovation Team of Medical Bioinformatics, Shenzhen University Medical School, Shenzhen 518060, China; Department of Cell Biology and Genetics, College of Basic Medicine, Shenzhen University Medical School, Shenzhen 518060, China.
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3
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Vickery JM, Toperzer JD, Raab JE, Lenz LL, Colgan SP, Russo BC. Synaptopodin is necessary for Shigella flexneri intercellular spread. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.25.537990. [PMID: 37163027 PMCID: PMC10168286 DOI: 10.1101/2023.04.25.537990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
For many intracellular pathogens, their virulence depends on an ability to spread between cells of an epithelial layer. For intercellular spread to occur, these pathogens deform the plasma membrane into a protrusion structure that is engulfed by the neighboring cell. Although the polymerization of actin is essential for spread, how these pathogens manipulate the actin cytoskeleton in a manner that enables protrusion formation is still incompletely understood. Here, we identify the mammalian actin binding protein synaptopodin as required for efficient intercellular spread. Using a model cytosolic pathogen, Shigella flexneri , we show that synaptopodin contributes to organization of actin around bacteria and increases the length of the actin tail at the posterior pole of the bacteria. We show that synaptopodin presence enables protrusions to form and to resolve at a greater rate, indicating that greater stability of the actin tail enables the bacteria to push against the membrane with greater force. We demonstrate that synaptopodin recruitment around bacteria requires the bacterial protein IcsA, and we show that this recruitment is further enhanced in a type 3 secretion system dependent manner. These data establish synaptopodin as required for intracellular bacteria to reprogram the actin cytoskeleton in a manner that enables efficient protrusion formation and enhance our understanding of the cellular function of synaptopodin. Authors Summary Intercellular spread is essential for many cytosolic dwelling pathogens during their infectious life cycle. Despite knowing the steps required for intercellular spread, relatively little is known about the host-pathogen interactions that enable these steps to occur. Here, we identify a requirement for the actin binding protein synaptopodin during intercellular spread by cytosolic bacteria. We show synaptopodin is necessary for the stability and recruitment of polymerized actin around bacteria. We also demonstrate synaptopodin is necessary to form plasma membrane structures known as protrusions that are necessary for the movement of these bacteria between cells. Thus, these findings implicate synaptopodin as an important actin-binding protein for the virulence of intracellular pathogens that require the actin cytoskeleton for their spread between cells.
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4
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Lynch JP, González-Prieto C, Reeves AZ, Bae S, Powale U, Godbole NP, Tremblay JM, Schmidt FI, Ploegh HL, Kansra V, Glickman JN, Leong JM, Shoemaker CB, Garrett WS, Lesser CF. Engineered Escherichia coli for the in situ secretion of therapeutic nanobodies in the gut. Cell Host Microbe 2023; 31:634-649.e8. [PMID: 37003258 PMCID: PMC10101937 DOI: 10.1016/j.chom.2023.03.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 12/20/2022] [Accepted: 03/08/2023] [Indexed: 04/03/2023]
Abstract
Drug platforms that enable the directed delivery of therapeutics to sites of diseases to maximize efficacy and limit off-target effects are needed. Here, we report the development of PROT3EcT, a suite of commensal Escherichia coli engineered to secrete proteins directly into their surroundings. These bacteria consist of three modular components: a modified bacterial protein secretion system, the associated regulatable transcriptional activator, and a secreted therapeutic payload. PROT3EcT secrete functional single-domain antibodies, nanobodies (Nbs), and stably colonize and maintain an active secretion system within the intestines of mice. Furthermore, a single prophylactic dose of a variant of PROT3EcT that secretes a tumor necrosis factor-alpha (TNF-α)-neutralizing Nb is sufficient to ablate pro-inflammatory TNF levels and prevent the development of injury and inflammation in a chemically induced model of colitis. This work lays the foundation for developing PROT3EcT as a platform for the treatment of gastrointestinal-based diseases.
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Affiliation(s)
- Jason P Lynch
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA 02115, USA; Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Coral González-Prieto
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA 02115, USA; Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Analise Z Reeves
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA 02115, USA; Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sena Bae
- Departments of Immunology and Infectious Diseases and Harvard T.H. Chan Center for the Microbiome in Public Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Urmila Powale
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA 02115, USA; Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Neha P Godbole
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA 02115, USA; Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jacqueline M Tremblay
- Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, MA 01536, USA
| | - Florian I Schmidt
- Institute of Innate Immunity, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Hidde L Ploegh
- Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | | | - Jonathan N Glickman
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02115, USA
| | - John M Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA; Tufts Stuart B Levy Center for Integrated Management of Antimicrobial Resistance, Tufts University, Boston, MA 02111, USA
| | - Charles B Shoemaker
- Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, MA 01536, USA; Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Wendy S Garrett
- Departments of Immunology and Infectious Diseases and Harvard T.H. Chan Center for the Microbiome in Public Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Cammie F Lesser
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA 02115, USA; Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Ragon Institute of Harvard and MIT, Cambridge, MA 02139, USA.
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5
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Wagner N, Alburquerque M, Ecker N, Dotan E, Zerah B, Pena MM, Potnis N, Pupko T. Natural language processing approach to model the secretion signal of type III effectors. FRONTIERS IN PLANT SCIENCE 2022; 13:1024405. [PMID: 36388586 PMCID: PMC9659976 DOI: 10.3389/fpls.2022.1024405] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Type III effectors are proteins injected by Gram-negative bacteria into eukaryotic hosts. In many plant and animal pathogens, these effectors manipulate host cellular processes to the benefit of the bacteria. Type III effectors are secreted by a type III secretion system that must "classify" each bacterial protein into one of two categories, either the protein should be translocated or not. It was previously shown that type III effectors have a secretion signal within their N-terminus, however, despite numerous efforts, the exact biochemical identity of this secretion signal is generally unknown. Computational characterization of the secretion signal is important for the identification of novel effectors and for better understanding the molecular translocation mechanism. In this work we developed novel machine-learning algorithms for characterizing the secretion signal in both plant and animal pathogens. Specifically, we represented each protein as a vector in high-dimensional space using Facebook's protein language model. Classification algorithms were next used to separate effectors from non-effector proteins. We subsequently curated a benchmark dataset of hundreds of effectors and thousands of non-effector proteins. We showed that on this curated dataset, our novel approach yielded substantially better classification accuracy compared to previously developed methodologies. We have also tested the hypothesis that plant and animal pathogen effectors are characterized by different secretion signals. Finally, we integrated the novel approach in Effectidor, a web-server for predicting type III effector proteins, leading to a more accurate classification of effectors from non-effectors.
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Affiliation(s)
- Naama Wagner
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Michael Alburquerque
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Noa Ecker
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Edo Dotan
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ben Zerah
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Michelle Mendonca Pena
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, United States
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, United States
| | - Tal Pupko
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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6
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icaR
and
icaT
Are Ancient Chromosome Genes Encoding Substrates of the Type III Secretion Apparatus in Shigella flexneri. mSphere 2022; 7:e0011522. [PMID: 35582904 PMCID: PMC9241512 DOI: 10.1128/msphere.00115-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shigella is an Escherichia coli pathovar that colonizes the cytosol of mucosal cells in the human large intestine. To do this, Shigella uses a Type III Secretion Apparatus (T3SA) to translocate several proteins into host cells. The T3SA and its substrates are encoded by genes of the virulence plasmid pINV or by chromosomal genes derived thereof. We recently discovered two chromosomal genes, which seem unrelated to pINV, although they are activated by MxiE and IpgC similarly to some of the canonical substrates of the T3SA. Here, we showed that the production of the corresponding proteins depended on the conservation of a MxiE box in their cognate promoters. Furthermore, both proteins were secreted by the T3SA in a chaperone-independent manner through the recognition of their respective amino-terminal secretion signal. Based on these observations, we named these new genes icaR and icaT, which stand for invasion chromosome antigen with homology for a transcriptional regulator and a transposase, respectively. icaR and icaT have orthologs in commensal and pathogenic E. coli strains belonging mainly to phylogroups A, B1, D and E. Finally, we demonstrated that icaR and icaT orthologs could be activated by the coproduction of IpgC and MxiE in strains MG1655 K-12 (phylogroup A) and O157:H7 ATCC 43888 (phylogroup E). In contrast, the coproduction of EivF and YgeG, which are homologs of MxiE and IpgC in the E. coli T3SS 2 (ETT2), failed to activate icaR and icaT. IMPORTANCEicaR and icaT are the latest members of the MxiE regulon discovered in the chromosome. The proteins IcaR and IcaT, albeit produced in small amounts, are nonetheless secreted by the T3SA comparably to canonical substrates. The high occurrence of icaR and icaT in phylogroups A, B1, D, and E coupled with their widespread absence in their B2 counterparts agree with the consensus E. coli phylogeny. The widespread conservation of the MxiE box among icaR and icaT orthologs supports the notion that both genes had already undergone coevolution with transcriptional activators ipgC and mxiE- harbored in pINV or a relative- in the last common ancestor of Shigella and of E. coli from phylogroups A, B1, D, and E. The possibility that icaR and icaT may contribute to Shigella pathogenesis cannot be excluded, although some of their characteristics suggest they are fossil genes.
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7
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Bajunaid W, Haidar-Ahmad N, Kottarampatel AH, Ourida Manigat F, Silué N, F. Tchagang C, Tomaro K, Campbell-Valois FX. The T3SS of Shigella: Expression, Structure, Function, and Role in Vacuole Escape. Microorganisms 2020; 8:microorganisms8121933. [PMID: 33291504 PMCID: PMC7762205 DOI: 10.3390/microorganisms8121933] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 12/18/2022] Open
Abstract
Shigella spp. are one of the leading causes of infectious diarrheal diseases. They are Escherichia coli pathovars that are characterized by the harboring of a large plasmid that encodes most virulence genes, including a type III secretion system (T3SS). The archetypal element of the T3SS is the injectisome, a syringe-like nanomachine composed of approximately 20 proteins, spanning both bacterial membranes and the cell wall, and topped with a needle. Upon contact of the tip of the needle with the plasma membrane, the injectisome secretes its protein substrates into host cells. Some of these substrates act as translocators or effectors whose functions are key to the invasion of the cytosol and the cell-to-cell spread characterizing the lifestyle of Shigella spp. Here, we review the structure, assembly, function, and methods to measure the activity of the injectisome with a focus on Shigella, but complemented with data from other T3SS if required. We also present the regulatory cascade that controls the expression of T3SS genes in Shigella. Finally, we describe the function of translocators and effectors during cell-to-cell spread, particularly during escape from the vacuole, a key element of Shigella’s pathogenesis that has yet to reveal all of its secrets.
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Affiliation(s)
- Waad Bajunaid
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Nathaline Haidar-Ahmad
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Anwer Hasil Kottarampatel
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - France Ourida Manigat
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Navoun Silué
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Caetanie F. Tchagang
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Kyle Tomaro
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - François-Xavier Campbell-Valois
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (W.B.); (N.H.-A.); (A.H.K.); (F.O.M.); (N.S.); (C.F.T.); (K.T.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Correspondence:
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8
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Serapio-Palacios A, Finlay BB. Dynamics of expression, secretion and translocation of type III effectors during enteropathogenic Escherichia coli infection. Curr Opin Microbiol 2020; 54:67-76. [PMID: 32058947 DOI: 10.1016/j.mib.2019.12.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/30/2019] [Indexed: 12/14/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) is an important cause of infant diarrhea and mortality worldwide. The locus of enterocyte effacement (LEE) pathogenicity island in the EPEC genome encodes a type 3 secretion system (T3SS). This nanomachine directly injects a sophisticated arsenal of effectors into host cells, which is critical for EPEC pathogenesis. To colonize the gut mucosa, EPEC alters its gene expression in response to host environmental signals. Regulation of the LEE has been studied extensively, revealing key mechanisms of transcriptional regulation, and more recently at the posttranscriptional and posttranslational levels. Moreover, the T3SS assembly and secretion is a highly coordinated process that ensures hierarchical delivery of effectors upon cell contact. EPEC effectors and virulence factors not only manipulate host cellular processes, but also modulate effector translocation by controlling T3SS formation. In this review, we focus on the regulation of EPEC virulence genes and modulation of effector secretion and translocation.
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Affiliation(s)
| | - Barton Brett Finlay
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada; Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
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9
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Burdette LA, Leach SA, Wong HT, Tullman-Ercek D. Developing Gram-negative bacteria for the secretion of heterologous proteins. Microb Cell Fact 2018; 17:196. [PMID: 30572895 PMCID: PMC6302416 DOI: 10.1186/s12934-018-1041-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 12/08/2018] [Indexed: 11/10/2022] Open
Abstract
Gram-negative bacteria are attractive hosts for recombinant protein production because they are fast growing, easy to manipulate, and genetically stable in large cultures. However, the utility of these microbes would expand if they also could secrete the product at commercial scales. Secretion of biotechnologically relevant proteins into the extracellular medium increases product purity from cell culture, decreases downstream processing requirements, and reduces overall cost. Thus, researchers are devoting significant attention to engineering Gram-negative bacteria to secrete recombinant proteins to the extracellular medium. Secretion from these bacteria operates through highly specialized systems, which are able to translocate proteins from the cytosol to the extracellular medium in either one or two steps. Building on past successes, researchers continue to increase the secretion efficiency and titer through these systems in an effort to make them viable for industrial production. Efforts include modifying the secretion tags required for recombinant protein secretion, developing methods to screen or select rapidly for clones with higher titer or efficiency, and improving reliability and robustness of high titer secretion through genetic manipulations. An additional focus is the expression of secretion machineries from pathogenic bacteria in the "workhorse" of biotechnology, Escherichia coli, to reduce handling of pathogenic strains. This review will cover recent advances toward the development of high-expressing, high-secreting Gram-negative production strains.
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Affiliation(s)
- Lisa Ann Burdette
- Department of Chemical and Biomolecular Engineering, University of California-Berkeley, Berkeley, USA
- Present Address: Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Samuel Alexander Leach
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, USA
| | - Han Teng Wong
- Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, USA
- Present Address: Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Danielle Tullman-Ercek
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, USA
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10
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Wang J, Li J, Yang B, Xie R, Marquez-Lago TT, Leier A, Hayashida M, Akutsu T, Zhang Y, Chou KC, Selkrig J, Zhou T, Song J, Lithgow T. Bastion3: a two-layer ensemble predictor of type III secreted effectors. Bioinformatics 2018; 35:2017-2028. [PMID: 30388198 PMCID: PMC7963071 DOI: 10.1093/bioinformatics/bty914] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/15/2018] [Accepted: 10/31/2018] [Indexed: 01/31/2023] Open
Abstract
MOTIVATION Type III secreted effectors (T3SEs) can be injected into host cell cytoplasm via type III secretion systems (T3SSs) to modulate interactions between Gram-negative bacterial pathogens and their hosts. Due to their relevance in pathogen-host interactions, significant computational efforts have been put toward identification of T3SEs and these in turn have stimulated new T3SE discoveries. However, as T3SEs with new characteristics are discovered, these existing computational tools reveal important limitations: (i) most of the trained machine learning models are based on the N-terminus (or incorporating also the C-terminus) instead of the proteins' complete sequences, and (ii) the underlying models (trained with classic algorithms) employed only few features, most of which were extracted based on sequence-information alone. To achieve better T3SE prediction, we must identify more powerful, informative features and investigate how to effectively integrate these into a comprehensive model. RESULTS In this work, we present Bastion3, a two-layer ensemble predictor developed to accurately identify type III secreted effectors from protein sequence data. In contrast with existing methods that employ single models with few features, Bastion3 explores a wide range of features, from various types, trains single models based on these features and finally integrates these models through ensemble learning. We trained the models using a new gradient boosting machine, LightGBM and further boosted the models' performances through a novel genetic algorithm (GA) based two-step parameter optimization strategy. Our benchmark test demonstrates that Bastion3 achieves a much better performance compared to commonly used methods, with an ACC value of 0.959, F-value of 0.958, MCC value of 0.917 and AUC value of 0.956, which comprehensively outperformed all other toolkits by more than 5.6% in ACC value, 5.7% in F-value, 12.4% in MCC value and 5.8% in AUC value. Based on our proposed two-layer ensemble model, we further developed a user-friendly online toolkit, maximizing convenience for experimental scientists toward T3SE prediction. With its design to ease future discoveries of novel T3SEs and improved performance, Bastion3 is poised to become a widely used, state-of-the-art toolkit for T3SE prediction. AVAILABILITY AND IMPLEMENTATION http://bastion3.erc.monash.edu/. CONTACT selkrig@embl.de or wyztli@163.com or or trevor.lithgow@monash.edu. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Jiawei Wang
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC, Australia
| | - Jiahui Li
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC, Australia,Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Bingjiao Yang
- School of Computer Science and Information Security, Guilin University of Electronic Technology, Guilin, China
| | - Ruopeng Xie
- School of Computer Science and Information Security, Guilin University of Electronic Technology, Guilin, China
| | - Tatiana T Marquez-Lago
- Department of Genetics, School of Medicine, University of Alabama at Birmingham, AL, USA,Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, AL, USA
| | - André Leier
- Department of Genetics, School of Medicine, University of Alabama at Birmingham, AL, USA,Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, AL, USA
| | - Morihiro Hayashida
- National Institute of Technology, Matsue College, Matsue, Shimane, Japan
| | - Tatsuya Akutsu
- Bioinformatics Center, Institute for Chemical Research, Kyoto University, Kyoto, Japan
| | - Yanju Zhang
- School of Computer Science and Information Security, Guilin University of Electronic Technology, Guilin, China
| | - Kuo-Chen Chou
- Gordon Life Science Institute, Boston, MA, USA,Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, China,Center of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, Jeddah, Saudi Arabia
| | - Joel Selkrig
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Tieli Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | | | - Trevor Lithgow
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC, Australia
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Molecular basis for CesT recognition of type III secretion effectors in enteropathogenic Escherichia coli. PLoS Pathog 2018; 14:e1007224. [PMID: 30118511 PMCID: PMC6114900 DOI: 10.1371/journal.ppat.1007224] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 08/29/2018] [Accepted: 07/17/2018] [Indexed: 11/19/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) use a needle-like injection apparatus known as the type III secretion system (T3SS) to deliver protein effectors into host cells. Effector translocation is highly stratified in EPEC with the translocated intimin receptor (Tir) being the first effector delivered into the host. CesT is a multi-cargo chaperone that is required for the secretion of Tir and at least 9 other effectors. However, the structural and mechanistic basis for differential effector recognition by CesT remains unclear. Here, we delineated the minimal CesT-binding region on Tir to residues 35–77 and determined the 2.74 Å structure of CesT bound to an N-terminal fragment of Tir. Our structure revealed that the CesT-binding region in the N-terminus of Tir contains an additional conserved sequence, distinct from the known chaperone-binding β-motif, that we termed the CesT-extension motif because it extends the β-sheet core of CesT. This motif is also present in the C-terminus of Tir that we confirmed to be a unique second CesT-binding region. Point mutations that disrupt CesT-binding to the N- or C-terminus of Tir revealed that the newly identified carboxy-terminal CesT-binding region was required for efficient Tir translocation into HeLa cells and pedestal formation. Furthermore, the CesT-extension motif was identified in the N-terminal region of NleH1, NleH2, and EspZ, and mutations that disrupt this motif reduced translocation of these effectors, and in some cases, overall effector stability, thus validating the universality of this CesT-extension motif. The presence of two CesT-binding regions in Tir, along with the presence of the CesT-extension motif in other highly translocated effectors, may contribute to differential cargo recognition by CesT. Enteropathogenic Escherichia coli injects effector proteins into host cells using a type III secretion system (T3SS). The translocated intimin receptor (Tir) is the first effector delivered into host cells and imparts efficient secretion of other effectors. However, the mechanism for Tir-dependent modulation of the T3SS is poorly understood. We provide evidence that the multi-cargo chaperone CesT binds to two regions in Tir at the N- and C-terminus through a specific recognition motif, and show that CesT binding to the Tir C-terminus is important for host translocation. Furthermore we show that the CesT-specific motif is conserved in a subset of highly translocated effectors. This study highlights the multi-faceted role that T3SS chaperones play in effector secretion dynamics.
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