1
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Navarro-Garcia F. Serine proteases autotransporter of Enterobacteriaceae: Structures, subdomains, motifs, functions, and targets. Mol Microbiol 2023; 120:178-193. [PMID: 37392318 DOI: 10.1111/mmi.15116] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 07/03/2023]
Abstract
Serine protease autotransporters of Enterobacteriaceae (SPATE) constitute a superfamily of virulence factors, resembling the trypsin-like superfamily of serine proteases. SPATEs accomplish multiple functions associated to disease development of their hosts, which could be the consequence of SPATE cleavage of host cell components. SPATEs have been divided into class-1 and class-2 based on structural differences and biological effects, including similar substrate specificity, cytotoxic effects on cultured cells, and enterotoxin activity on intestinal tissues for class-1 SPATEs, whereas most class-2 SPATEs exhibit a lectin-like activity with a predilection to degrade a variety of mucins, including leukocyte surface O-glycoproteins and soluble host proteins, resulting in mucosal colonization and immune modulation. In this review, the structure of class-1 and class-2 are analyzed, making emphasis on their putative functional subdomains as well as a description of their function is provided, including prototypical mechanism of action.
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Affiliation(s)
- Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN, Mexico, Mexico
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2
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Qin J, Hong Y, Morona R, Totsika M. Cysteine-Dependent Conformational Heterogeneity of Shigella flexneri Autotransporter IcsA and Implications of Its Function. Microbiol Spectr 2022; 10:e0341022. [PMID: 36374106 PMCID: PMC9769942 DOI: 10.1128/spectrum.03410-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/30/2022] [Indexed: 11/16/2022] Open
Abstract
Shigella IcsA is a versatile surface virulence factor required for early and late pathogenesis stages extracellularly and intracellularly. Despite IcsA serving as a model Type V secretion system (T5SS) autotransporter to study host-pathogen interactions, its detailed molecular architecture is poorly understood. Recently, IcsA was found to switch to a different conformation for its adhesin activity upon sensing the host stimuli by Shigella Type III secretion system (T3SS). Here, we reported that the single cysteine residue (C130) near the N terminus of the IcsA passenger had a role in IcsA adhesin activity. We also showed that the IcsA passenger (IcsAp) existed in multiple conformations, and the conformation populations were influenced by a central pair of cysteine residues (C375 and C379), which was not previously reported for any Type V autotransporter passengers. Disruption of either or both central cysteine residues altered the exposure of IcsA epitopes to polyclonal anti-IcsA antibodies previously shown to block Shigella adherence, yet without loss of IcsA intracellular functions in actin-based motility (ABM). Anti-IcsA antibody reactivity was restored when the IcsA-paired cysteine substitution mutants were expressed in an ΔipaD background with a constitutively active T3SS, highlighting an interplay between T3SS and T5SS. The work here uncovered a novel molecular switch empowered by a centrally localized, short-spaced cysteine pair in the Type V autotransporter IcsA that ensured conformational heterogeneity to aid IcsA evasion of host immunity. IMPORTANCE Shigella species are the leading cause of diarrheal-related death globally by causing bacillary dysentery. The surface virulence factor IcsA, which is essential for Shigella pathogenesis, is a unique multifunctional autotransporter that is responsible for cell adhesion, and actin-based motility, yet detailed mechanistic understanding is lacking. Here, we showed that the three cysteine residues in IcsA contributed to the protein's distinct functions. The N-terminal cysteine residue within the IcsA passenger domain played a role in adhesin function, while a centrally localized cysteine pair provided conformational heterogeneity that resulted in IcsA molecules with different reactivity to adhesion-blocking anti-IcsA antibodies. In synergy with the Type III secretion system, this molecular switch preserved biological function in distinct IcsA conformations for cell adhesion, actin-based motility, and autophagy escape, providing a potential strategy by which Shigella evades host immunity and targets this essential virulence factor.
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Affiliation(s)
- Jilong Qin
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Yaoqin Hong
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Renato Morona
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Makrina Totsika
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
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3
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Vo JL, Ortiz GCM, Totsika M, Lo AW, Hancock SJ, Whitten AE, Hor L, Peters KM, Ageorges V, Caccia N, Desvaux M, Schembri MA, Paxman JJ, Heras B. Variation of Antigen 43 self-association modulates bacterial compacting within aggregates and biofilms. NPJ Biofilms Microbiomes 2022; 8:20. [PMID: 35396507 PMCID: PMC8993888 DOI: 10.1038/s41522-022-00284-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 03/03/2022] [Indexed: 12/13/2022] Open
Abstract
The formation of aggregates and biofilms enhances bacterial colonisation and infection progression by affording protection from antibiotics and host immune factors. Despite these advantages there is a trade-off, whereby bacterial dissemination is reduced. As such, biofilm development needs to be controlled to suit adaptation to different environments. Here we investigate members from one of largest groups of bacterial adhesins, the autotransporters, for their critical role in the assembly of bacterial aggregates and biofilms. We describe the structural and functional characterisation of autotransporter Ag43 variants from different Escherichia coli pathotypes. We show that specific interactions between amino acids on the contacting interfaces of adjacent Ag43 proteins drives a common mode of trans-association that leads to cell clumping. Furthermore, subtle variation of these interactions alters aggregation kinetics and the degree of compacting within cell clusters. Together, our structure–function investigation reveals an underlying molecular basis for variations in the density of bacterial communities.
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Affiliation(s)
- Julieanne L Vo
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Gabriela C Martínez Ortiz
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Makrina Totsika
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Herston, QLD, 4006, Australia
| | - Alvin W Lo
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Steven J Hancock
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Andrew E Whitten
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Lilian Hor
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Kate M Peters
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Valentin Ageorges
- Université Clermont Auvergne, INRAE, UMR454 MEDiS, 63000, Clermont-Ferrand, France
| | - Nelly Caccia
- Université Clermont Auvergne, INRAE, UMR454 MEDiS, 63000, Clermont-Ferrand, France
| | - Mickaël Desvaux
- Université Clermont Auvergne, INRAE, UMR454 MEDiS, 63000, Clermont-Ferrand, France
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, 4072, Australia.
| | - Jason J Paxman
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia.
| | - Begoña Heras
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia.
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4
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Awadelkareem AM, Al-Shammari E, Elkhalifa AO, Adnan M, Siddiqui AJ, Mahmood D, Azad ZRAA, Patel M, Mehmood K, Danciu C, Ashraf SA. Anti-Adhesion and Antibiofilm Activity of Eruca sativa Miller Extract Targeting Cell Adhesion Proteins of Food-Borne Bacteria as a Potential Mechanism: Combined In Vitro-In Silico Approach. PLANTS (BASEL, SWITZERLAND) 2022; 11:610. [PMID: 35270080 PMCID: PMC8912376 DOI: 10.3390/plants11050610] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 05/05/2023]
Abstract
Bacterial cells have the ability to form biofilm onto the surfaces of food matrixes and on food processing equipment, leading to a source of food contamination posing serious health implications. Therefore, our study aimed to determine the effect of Eruca sativa Miller (E. sativa) crude extract against biofilms of food-borne bacteria along with in silico approaches to investigate adhesion proteins responsible for biofilm activity against the identified phytochemicals. The antibacterial potential of crude extract was evaluated using agar well diffusion technique and combinations of light and scanning electron microscopy to assess the efficacy of crude extract against the developed biofilms. Our results showed that crude extract of E. sativa was active against all tested food-borne bacteria, exhibiting a rapid kinetics of killing bacteria in a time-dependent manner. MIC and MBC values of E. sativa crude extract were found to be ranging from 125 to 500 µg/mL and 250 to 1000 µg/mL respectively. Furthermore, inhibition of developed biofilm by E sativa was found to be ranging from 58.68% to 73.45% for all the tested strains. The crude extract also reduced the viability of bacterial cells within biofilms and amount of EPS (ranging 59.73-82.77%) in the biofilm matrix. Additionally, the microscopic images also revealed significant disruption in the structure of biofilms. A molecular docking analysis of E. sativa phytochemicals showed interaction with active site of adhesion proteins Sortase A, EspA, OprD, and type IV b pilin of S. aureus, E. coli, P. aeruginosa, and S. enterica ser. typhi, respectively. Thus, our findings represent the first demonstration of E. sativa crude extract's bioactivity and potency against food-borne bacteria in their planktonic forms, as well as against the developed biofilms. Therefore, a possible mechanistic approach for inhibition of biofilm via targeting adhesion proteins can be explored further to target biofilm producing food-borne bacterial pathogens.
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Affiliation(s)
- Amir Mahgoub Awadelkareem
- Department of Clinical Nutrition, College of Applied Medical Sciences, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia; (A.M.A.); (E.A.-S.); (A.O.E.)
| | - Eyad Al-Shammari
- Department of Clinical Nutrition, College of Applied Medical Sciences, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia; (A.M.A.); (E.A.-S.); (A.O.E.)
| | - AbdElmoneim O. Elkhalifa
- Department of Clinical Nutrition, College of Applied Medical Sciences, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia; (A.M.A.); (E.A.-S.); (A.O.E.)
| | - Mohd Adnan
- Department of Biology, College of Science, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia; (M.A.); (A.J.S.)
| | - Arif Jamal Siddiqui
- Department of Biology, College of Science, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia; (M.A.); (A.J.S.)
| | - Danish Mahmood
- Department of Pharmacology and Toxicology, Unaizah College of Pharmacy, Qassim University, P.O. Box 6688, Qassim 51452, Saudi Arabia;
| | - Z. R. Azaz Ahmad Azad
- Department of Post-Harvest Engineering and Technology, Aligarh Muslim University, Aligarh 202002, India;
| | - Mitesh Patel
- Bapalal Vaidya Botanical Research Centre, Department of Biosciences, Veer Narmad South Gujarat University, Surat 395007, India;
| | - Khalid Mehmood
- Department of Pharmaceutics, College of Pharmacy, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia;
| | - Corina Danciu
- Department of Pharmacognosy, Faculty of Pharmacy, “Victor Babes” University of Medicine and Pharmacy, 2 Eftimie Murgu Square, 300041 Timisoara, Romania;
| | - Syed Amir Ashraf
- Department of Clinical Nutrition, College of Applied Medical Sciences, University of Hail, P.O. Box 2440, Hail 34464, Saudi Arabia; (A.M.A.); (E.A.-S.); (A.O.E.)
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5
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Adnan M, Patel M, Deshpande S, Alreshidi M, Siddiqui AJ, Reddy MN, Emira N, De Feo V. Effect of Adiantum philippense Extract on Biofilm Formation, Adhesion With Its Antibacterial Activities Against Foodborne Pathogens, and Characterization of Bioactive Metabolites: An in vitro-in silico Approach. Front Microbiol 2020; 11:823. [PMID: 32477292 PMCID: PMC7237743 DOI: 10.3389/fmicb.2020.00823] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 04/06/2020] [Indexed: 12/13/2022] Open
Abstract
Adiantum philippense (A. philippense), an ethnomedicinally important fern, has become an interesting herb in the search for novel bioactive metabolites, which can also be used as therapeutic agents. Primarily, in this study, A. philippense crude extract was screened for its phytochemical constituents, antagonistic potential, and effect on bacterial adhesion and biofilm formation against common food pathogens. Phytochemical profiling of A. philippense was carried out by using High Resolution-Liquid Chromatography and Mass Spectroscopy (HR-LCMS) followed by antibacterial activity via agar cup/well diffusion, broth microdilution susceptibility methods, and growth curve analysis. Antibiofilm potency and efficacy were assessed on the development, formation, and texture of biofilms through light microscopy, fluorescent microscopy, scanning electron microscopy, and the assessment of exopolysaccharide production. Correspondingly, a checkerboard test was performed to evaluate the combinatorial effect of A. philippense and chloramphenicol. Lastly, molecular docking studies of identified phytochemicals with adhesin proteins of tested food pathogens, which helps the bacteria in surface attachment and leads to biofilm formation, were assessed. A. philippense crude extract was found to be active against all tested food pathogens, displaying the rapid time-dependent kinetics of bacterial killing. A. philippense crude extract also impedes the biofilm matrix by reducing the total content of exopolysaccharide, and, likewise, the microscopic images revealed a great extent of disruption in the architecture of biofilms. A synergy was observed between A. philippense crude extract and chloramphenicol for E. coli, S. aureus, and P. aeruginosa, whereas an additive effect was observed for S. flexneri. Various bioactive phytochemicals were categorized from A. philippense crude extract using HR-LCMS. The molecular docking of these identified phytochemicals was interrelated with the active site residues of adhesin proteins, IcsA, Sortase A, OprD, EspA, and FimH from S. flexneri, S. aureus, P. aeruginosa, and E. coli, respectively. Thus, our findings represent the bioactivity and potency of A. philippense crude extract against food pathogens not only in their planktonic forms but also against/in biofilms for the first time. We have also correlated these findings with the possible mechanism of biofilm inhibition via targeting adhesin proteins, which could be explored further to design new bioactive compounds against biofilm producing foodborne bacterial pathogens.
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Affiliation(s)
- Mohd Adnan
- Department of Biology, College of Science, University of Ha'il, Ha'il, Saudi Arabia
| | - Mitesh Patel
- Department of Biosciences, Bapalal Vaidya Botanical Research Centre, Veer Narmad South Gujarat University, Surat, India
| | - Sumukh Deshpande
- Central Biotechnology Services, College of Biomedical and Life Sciences, Cardiff University, Cardiff, United Kingdom
| | - Mousa Alreshidi
- Department of Biology, College of Science, University of Ha'il, Ha'il, Saudi Arabia
| | - Arif Jamal Siddiqui
- Department of Biology, College of Science, University of Ha'il, Ha'il, Saudi Arabia
| | - Mandadi Narsimha Reddy
- Department of Biosciences, Bapalal Vaidya Botanical Research Centre, Veer Narmad South Gujarat University, Surat, India
| | - Noumi Emira
- Department of Biology, College of Science, University of Ha'il, Ha'il, Saudi Arabia
| | - Vincenzo De Feo
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, Fisciano, Italy
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6
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The virulence domain of Shigella IcsA contains a subregion with specific host cell adhesion function. PLoS One 2020; 15:e0227425. [PMID: 31910229 PMCID: PMC6946128 DOI: 10.1371/journal.pone.0227425] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/18/2019] [Indexed: 02/08/2023] Open
Abstract
Shigella species cause bacillary dysentery, especially among young individuals. Shigellae target the human colon for invasion; however, the initial adhesion mechanism is poorly understood. The Shigella surface protein IcsA, in addition to its role in actin-based motility, acts as a host cell adhesin through unknown mechanism(s). Here we confirmed the role of IcsA in cell adhesion and defined the region required for IcsA adhesin activity. Purified IcsA passenger domain was able block S. flexneri adherence and was also used as a molecular probe that recognised multiple components from host cells. The region within IcsA's functional passenger domain (aa 138-148) was identified by mutagenesis. Upon the deletion of this region, the purified IcsAΔ138-148 was found to no longer block S. flexneri adherence and had reduced ability to interact with host molecules. Furthermore, S. flexneri expressing IcsAΔ138-148 was found to be significantly defective in both cell adherence and invasion. Taken together, our data identify an adherence region within the IcsA functional domain and provides useful information for designing therapeutics for Shigella infection.
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7
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Rojas-Lopez M, Zorgani MA, Kelley LA, Bailly X, Kajava AV, Henderson IR, Polticelli F, Pizza M, Rosini R, Desvaux M. Identification of the Autochaperone Domain in the Type Va Secretion System (T5aSS): Prevalent Feature of Autotransporters with a β-Helical Passenger. Front Microbiol 2018; 8:2607. [PMID: 29375499 PMCID: PMC5767081 DOI: 10.3389/fmicb.2017.02607] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/14/2017] [Indexed: 11/29/2022] Open
Abstract
Autotransporters (ATs) belong to a family of modular proteins secreted by the Type V, subtype a, secretion system (T5aSS) and considered as an important source of virulence factors in lipopolysaccharidic diderm bacteria (archetypical Gram-negative bacteria). While exported by the Sec pathway, the ATs are further secreted across the outer membrane via their own C-terminal translocator forming a β-barrel, through which the rest of the protein, namely the passenger, can pass. In several ATs, an autochaperone domain (AC) present at the C-terminal region of the passenger and upstream of the translocator was demonstrated as strictly required for proper secretion and folding. However, considering it was functionally characterised and identified only in a handful of ATs, wariness recently fells on the commonality and conservation of this structural element in the T5aSS. To circumvent the issue of sequence divergence and taking advantage of the resolved three-dimensional structure of some ACs, identification of this domain was performed following structural alignment among all AT passengers experimentally resolved by crystallography before searching in a dataset of 1523 ATs. While demonstrating that the AC is indeed a conserved structure found in numerous ATs, phylogenetic analysis further revealed a distribution into deeply rooted branches, from which emerge 20 main clusters. Sequence analysis revealed that an AC could be identified in the large majority of SAATs (self-associating ATs) but not in any LEATs (lipase/esterase ATs) nor in some PATs (protease autotransporters) and PHATs (phosphatase/hydrolase ATs). Structural analysis indicated that an AC was present in passengers exhibiting single-stranded right-handed parallel β-helix, whatever the type of β-solenoid, but not with α-helical globular fold. From this investigation, the AC of type 1 appears as a prevalent and conserved structural element exclusively associated to β-helical AT passenger and should promote further studies about the protein secretion and folding via the T5aSS, especially toward α-helical AT passengers.
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Affiliation(s)
- Maricarmen Rojas-Lopez
- Université Clermont Auvergne, INRA, UMR454 MEDiS, Clermont-Ferrand, France.,GSK, Siena, Italy
| | - Mohamed A Zorgani
- Université Clermont Auvergne, INRA, UMR454 MEDiS, Clermont-Ferrand, France
| | - Lawrence A Kelley
- Structural Bioinformatics Group, Imperial College London, London, United Kingdom
| | - Xavier Bailly
- Institut National de la Recherche Agronomique, UR346 Epidémiologie Animale, Saint Genès Champanelle, France
| | - Andrey V Kajava
- CRBM UMR5237 CNRS, Institut de Biologie Computationnelle, Université Montpellier, Montpellier, France
| | - Ian R Henderson
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Fabio Polticelli
- Department of Sciences, National Institute of Nuclear Physics, Roma Tre University, Rome, Italy
| | | | | | - Mickaël Desvaux
- Université Clermont Auvergne, INRA, UMR454 MEDiS, Clermont-Ferrand, France
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8
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Abstract
Cardiolipin, an anionic phospholipid that resides at the poles of the inner and outer membranes, is synthesized primarily by the putative cardiolipin synthase ClsA in Shigella flexneri. An S. flexneri clsA mutant had no cardiolipin detected within its membrane, grew normally in vitro, and invaded cultured epithelial cells, but it failed to form plaques in epithelial cell monolayers, indicating that cardiolipin is required for virulence. The clsA mutant was initially motile within the host cell cytoplasm but formed filaments and lost motility during replication and failed to spread efficiently to neighboring cells. Mutation of pbgA, which encodes the transporter for cardiolipin from the inner membrane to the outer membrane, also resulted in loss of plaque formation. The S. flexneri pbgA mutant had normal levels of cardiolipin in the inner membrane, but no cardiolipin was detected in the outer membrane. The pbgA mutant invaded and replicated normally within cultured epithelial cells but failed to localize the actin polymerization protein IcsA properly on the bacterial surface and was unable to spread to neighboring cells. The clsA mutant, but not the pbgA mutant, had increased phosphatidylglycerol in the outer membrane. This appeared to compensate partially for the loss of cardiolipin in the outer membrane, allowing some IcsA localization in the outer membrane of the clsA mutant. We propose a dual function for cardiolipin in S. flexneri pathogenesis. In the inner membrane, cardiolipin is essential for proper cell division during intracellular growth. In the outer membrane, cardiolipin facilitates proper presentation of IcsA on the bacterial surface. The human pathogen Shigella flexneri causes bacterial dysentery by invading colonic epithelial cells, rapidly multiplying within their cytoplasm, and then spreading intercellularly to neighboring cells. Worldwide, Shigella spp. infect hundreds of millions of people annually, with fatality rates up to 15%. Antibiotic treatment of Shigella infections is compromised by increasing antibiotic resistance, and there is no approved vaccine to prevent future infections. This has created a growing need to understand Shigella pathogenesis and identify new targets for antimicrobial therapeutics. Here we show a previously unknown role of phospholipids in S. flexneri pathogenesis. We demonstrate that cardiolipin is required in the outer membrane for proper surface localization of IcsA and in the inner membrane for cell division during growth in the host cell cytoplasm.
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9
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Leupold S, Büsing P, Mas PJ, Hart DJ, Scrima A. Structural insights into the architecture of the Shigella flexneri virulence factor IcsA/VirG and motifs involved in polar distribution and secretion. J Struct Biol 2017; 198:19-27. [PMID: 28268178 DOI: 10.1016/j.jsb.2017.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/23/2017] [Accepted: 03/03/2017] [Indexed: 12/12/2022]
Abstract
IcsA/VirG is a key virulence factor of the human pathogen Shigella flexneri, acting as both an adhesin and actin-polymerizing factor during infection. We identified a soluble expression construct of the IcsA/VirG α-domain using the ESPRIT library screening system and determined its structure to 1.9Å resolution. In addition to the previously characterized autochaperone domain, our structure reveals a new domain, which shares a common fold with the autochaperone domains of various autotransporters. We further provide insight into the previously structurally uncharacterized β-helix domain that harbors the polar targeting motif and passenger-associated transport repeat. This structure is the first of any member of the recently identified passenger-associated transport repeat-containing autotransporters. Thus, it provides new insights into the overall architecture of this class of autotransporters, the function of the identified additional autochaperone domain and the structural properties of motifs involved in polar targeting and secretion of the Shigella flexneri virulence factor IcsA/VirG.
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Affiliation(s)
- Stefan Leupold
- Structural Biology of Autophagy, Helmholtz-Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Petra Büsing
- Structural Biology of Autophagy, Helmholtz-Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Philippe J Mas
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Darren J Hart
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Andrea Scrima
- Structural Biology of Autophagy, Helmholtz-Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany.
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10
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Mauricio RPM, Jeffries CM, Svergun DI, Deane JE. The Shigella Virulence Factor IcsA Relieves N-WASP Autoinhibition by Displacing the Verprolin Homology/Cofilin/Acidic (VCA) Domain. J Biol Chem 2017; 292:134-145. [PMID: 27881679 PMCID: PMC5217673 DOI: 10.1074/jbc.m116.758003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/09/2016] [Indexed: 11/10/2022] Open
Abstract
Shigella flexneri is a bacterial pathogen that invades cells of the gastrointestinal tract, causing severe dysentery. Shigella mediates intracellular motility and spreading via actin comet tail formation. This process is dependent on the surface-exposed, membrane-embedded virulence factor IcsA, which recruits the host actin regulator N-WASP. Although it is clear that Shigella requires N-WASP for this process, the molecular details of this interaction and the mechanism of N-WASP activation remain poorly understood. Here, we show that co-expression of full-length IcsA and the Shigella membrane protease IcsP yields highly pure IcsA passenger domain (residues 53-758). We show that IcsA is monomeric and describe the solution structure of the passenger domain obtained by small-angle X-ray scattering (SAXS) analysis. The SAXS-derived models suggest that IcsA has an elongated shape but, unlike most other autotransporter proteins, possesses a central kink revealing a distinctly curved structure. Pull-down experiments show direct binding of the IcsA passenger domain to both the WASP homology 1 (WH1) domain and the GTPase binding domain (GBD) of N-WASP and no binding to the verprolin homology/cofilin/acidic (VCA) region. Using fluorescence polarization experiments, we demonstrate that IcsA binding to the GBD region displaces the VCA peptide and that this effect is synergistically enhanced upon IcsA binding to the WH1 region. Additionally, domain mapping of the IcsA interaction interface reveals that different regions of IcsA bind to the WH1 and GBD domains of N-WASP. Taken together, our data support a model where IcsA and N-WASP form a tight complex releasing the N-WASP VCA domain to recruit the host cell machinery for actin tail formation.
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Affiliation(s)
- Rui P M Mauricio
- From the Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom and
| | - Cy M Jeffries
- the European Molecular Biology Laboratory (EMBL), Hamburg Outstation, c/o DESY, Hamburg 22067, Germany
| | - Dmitri I Svergun
- the European Molecular Biology Laboratory (EMBL), Hamburg Outstation, c/o DESY, Hamburg 22067, Germany
| | - Janet E Deane
- From the Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom and
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11
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Oberhettinger P, Leo JC, Linke D, Autenrieth IB, Schütz MS. The inverse autotransporter intimin exports its passenger domain via a hairpin intermediate. J Biol Chem 2014; 290:1837-49. [PMID: 25488660 DOI: 10.1074/jbc.m114.604769] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Autotransporter proteins comprise a large family of virulence factors that consist of a β-barrel translocation unit and an extracellular effector or passenger domain. The β-barrel anchors the protein to the outer membrane of Gram-negative bacteria and facilitates the transport of the passenger domain onto the cell surface. By inserting an epitope tag into the N terminus of the passenger domain of the inverse autotransporter intimin, we generated a mutant defective in autotransport. Using this stalled mutant, we could show that (i) at the time point of stalling, the β-barrel appears folded; (ii) the stalled autotransporter is associated with BamA and SurA; (iii) the stalled intimin is decorated with large amounts of SurA; (iv) the stalled autotransporter is not degraded by periplasmic proteases; and (v) inverse autotransporter passenger domains are translocated by a hairpin mechanism. Our results suggest a function for the BAM complex not only in insertion and folding of the β-barrel but also for passenger translocation.
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Affiliation(s)
- Philipp Oberhettinger
- From the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany and
| | - Jack C Leo
- the Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Dirk Linke
- the Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Ingo B Autenrieth
- From the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany and
| | - Monika S Schütz
- From the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany and
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12
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Drobnak I, Braselmann E, Chaney JL, Leyton DL, Bernstein HD, Lithgow T, Luirink J, Nataro JP, Clark PL. Of linkers and autochaperones: an unambiguous nomenclature to identify common and uncommon themes for autotransporter secretion. Mol Microbiol 2014; 95:1-16. [PMID: 25345653 DOI: 10.1111/mmi.12838] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2014] [Indexed: 01/02/2023]
Abstract
Autotransporter (AT) proteins provide a diverse array of important virulence functions to Gram-negative bacterial pathogens, and have also been adapted for protein surface display applications. The 'autotransporter' moniker refers to early models that depicted these proteins facilitating their own translocation across the bacterial outer membrane. Although translocation is less autonomous than originally proposed, AT protein segments upstream of the C-terminal transmembrane β-barrel have nevertheless consistently been found to contribute to efficient translocation and/or folding of the N-terminal virulence region (the 'passenger'). However, defining the precise secretion functions of these AT regions has been complicated by the use of multiple overlapping and ambiguous terms to define AT sequence, structural, and functional features, including 'autochaperone', 'linker' and 'junction'. Moreover, the precise definitions and boundaries of these features vary among ATs and even among research groups, leading to an overall murky picture of the contributions of specific features to translocation. Here we propose a unified, unambiguous nomenclature for AT structural, functional and conserved sequence features, based on explicit criteria. Applied to 16 well-studied AT proteins, this nomenclature reveals new commonalities for translocation but also highlights that the autochaperone function is less closely associated with a conserved sequence element than previously believed.
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Affiliation(s)
- Igor Drobnak
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
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13
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van Ulsen P, Rahman SU, Jong WS, Daleke-Schermerhorn MH, Luirink J. Type V secretion: From biogenesis to biotechnology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1592-611. [DOI: 10.1016/j.bbamcr.2013.11.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/01/2013] [Accepted: 11/13/2013] [Indexed: 12/13/2022]
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14
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Teh MY, Morona R. Identification of Shigella flexneri IcsA residues affecting interaction with N-WASP, and evidence for IcsA-IcsA co-operative interaction. PLoS One 2013; 8:e55152. [PMID: 23405119 PMCID: PMC3566212 DOI: 10.1371/journal.pone.0055152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 12/21/2012] [Indexed: 12/17/2022] Open
Abstract
The Shigella flexneri IcsA (VirG) protein is a polarly distributed outer membrane protein that is a fundamental virulence factor which interacts with neural Wiskott-Aldrich syndrome protein (N-WASP). The activated N-WASP then activates the Arp2/3 complex which initiates de novo actin nucleation and polymerisation to form F-actin comet tails and allows bacterial cell-to-cell spreading. In a previous study, IcsA was found to have three N-WASP interacting regions (IRs): IR I (aa 185-312), IR II (aa 330-382) and IR III (aa 508-730). The aim of this study was to more clearly define N-WASP interacting regions II and III by site-directed mutagenesis of specific amino acids. Mutant IcsA proteins were expressed in both smooth lipopolysaccharide (S-LPS) and rough LPS (R-LPS) S. flexneri strains and characterised for IcsA production level, N-WASP recruitment and F-actin comet tail formation. We have successfully identified new amino acids involved in N-WASP recruitment within different N-WASP interacting regions, and report for the first time using co-expression of mutant IcsA proteins, that N-WASP activation involves interactions with different regions on different IcsA molecules as shown by Arp3 recruitment. In addition, our findings suggest that autochaperone (AC) mutant protein production was not rescued by another AC region provided in trans, differing to that reported for two other autotransporters, PrtS and BrkA autotransporters.
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Affiliation(s)
- Min Yan Teh
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
| | - Renato Morona
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
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15
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Teh MY, Tran ENH, Morona R. Absence of O antigen suppresses Shigella flexneri IcsA autochaperone region mutations. MICROBIOLOGY-SGM 2012; 158:2835-2850. [PMID: 22936034 DOI: 10.1099/mic.0.062471-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Shigella flexneri IcsA (VirG) protein is a polarly distributed autotransporter protein. IcsA functions as a virulence factor by interacting with the host actin regulatory protein N-WASP, which in turn activates the Arp2/3 complex, initiating actin polymerization. Formation of F-actin comet tails allows bacterial cell-to-cell spreading. Although various accessory proteins such as periplasmic chaperones and the β-barrel assembly machine (BAM) complex have been shown to be involved in the export of IcsA, the IcsA translocation mechanism remains to be fully elucidated. A putative autochaperone (AC) region (amino acids 634-735) located at the C-terminal end of the IcsA passenger domain, which forms part of the self-associating autotransporter (SAAT) domain, has been suggested to be required for IcsA biogenesis, as well as for N-WASP recruitment, based on mutagenesis studies. IcsA(i) proteins with linker insertion mutations within the AC region have a significant reduction in production and are defective in N-WASP recruitment when expressed in smooth LPS (S-LPS) S. flexneri. In this study, we have found that the LPS O antigen plays a role in IcsA(i) production based on the use of an rmlD (rfbD) mutant having rough LPS (R-LPS) and a novel assay in which O antigen is depleted using tunicamycin treatment and then regenerated. In addition, we have identified a new N-WASP binding/interaction site within the IcsA AC region.
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Affiliation(s)
- Min Yan Teh
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| | - Elizabeth Ngoc Hoa Tran
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| | - Renato Morona
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
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16
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Abstract
Much is known about the molecular effectors of pathogenicity of gram-negative enteric pathogens, among which Shigella can be considered a model. This is due to its capacity to recapitulate the multiple steps required for a pathogenic microbe to survive close to its mucosal target, colonize and then invade its epithelial surface, cause its inflammatory destruction and simultaneously regulate the extent of the elicited innate response to likely survive the encounter and achieve successful subsequent transmission. These various steps of the infectious process represent an array of successive environmental conditions to which the bacteria need to successfully adapt. These conditions represent the selective pressure that triggered the "arms race" in which Shigella acquired the genetic and molecular effectors of its pathogenic armory, including the regulatory hierarchies that regulate the expression and function of these effectors. They also represent cues through which Shigella achieves the temporo-spatial expression and regulation of its virulence effectors. The role of such environmental cues has recently become obvious in the case of the major virulence effector of Shigella, the type three secretion system (T3SS) and its dedicated secreted virulence effectors. It needs to be better defined for other major virulence components such as the LPS and peptidoglycan which are used as examples here, in addition to the T3SS as models of regulation as it relates to the assembly and functional regulation of complex macromolecular systems of the bacterial surface. This review also stresses the need to better define what the true and relevant environmental conditions can be at the various steps of the progression of infection. The "identity" of the pathogen differs depending whether it is cultivated under in vitro or in vivo conditions. Moreover, this "identity" may quickly change during its progression into the infected tissue. Novel concepts and relevant tools are needed to address this challenge in microbial pathogenesis.
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Affiliation(s)
- Benoit Marteyn
- Unité de Pathogénie Microbienne Moléculaire; Institut Pasteur; Paris, France,Unité INSERM 786; Institut Pasteur; Paris, France
| | - Anastasia Gazi
- Unité de Pathogénie Microbienne Moléculaire; Institut Pasteur; Paris, France,Unité INSERM 786; Institut Pasteur; Paris, France
| | - Philippe Sansonetti
- Unité de Pathogénie Microbienne Moléculaire; Institut Pasteur; Paris, France,Unité INSERM 786; Institut Pasteur; Paris, France,Chaire de Microbiologie et Maladies Infectieuses; Collège de France; Paris, France,Correspondence to: Philippe Sansonetti,
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17
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Khan S, Mian HS, Sandercock LE, Chirgadze NY, Pai EF. Crystal structure of the passenger domain of the Escherichia coli autotransporter EspP. J Mol Biol 2011; 413:985-1000. [PMID: 21964244 DOI: 10.1016/j.jmb.2011.09.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 09/08/2011] [Accepted: 09/14/2011] [Indexed: 10/17/2022]
Abstract
Autotransporters represent a large superfamily of known and putative virulence factors produced by Gram-negative bacteria. They consist of an N-terminal "passenger domain" responsible for the specific effector functions of the molecule and a C-terminal "β-domain" responsible for translocation of the passenger across the bacterial outer membrane. Here, we present the 2.5-Å crystal structure of the passenger domain of the extracellular serine protease EspP, produced by the pathogen Escherichia coli O157:H7 and a member of the serine protease autotransporters of Enterobacteriaceae (SPATEs). Like the previously structurally characterized SPATE passenger domains, the EspP passenger domain contains an extended right-handed parallel β-helix preceded by an N-terminal globular domain housing the catalytic function of the protease. Of note, however, is the absence of a second globular domain protruding from this β-helix. We describe the structure of the EspP passenger domain in the context of previous results and provide an alternative hypothesis for the function of the β-helix within SPATEs.
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Affiliation(s)
- Shekeb Khan
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, University Health Network, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L7
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