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Chacko FM, Schmitt L. Interaction of RTX toxins with the host cell plasma membrane. Biol Chem 2023:hsz-2022-0336. [PMID: 36907826 DOI: 10.1515/hsz-2022-0336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/27/2023] [Indexed: 03/14/2023]
Abstract
Repeats in ToXins (RTX) protein family is a group of exoproteins secreted by Type 1 secretion system (T1SS) of several Gram-negative bacteria. The term RTX is derived from the characteristic nonapeptide sequence (GGxGxDxUx) present at the C-terminus of the protein. This RTX domain binds to calcium ions in the extracellular medium after being secreted out of the bacterial cells, and this facilitates folding of the entire protein. The secreted protein then binds to the host cell membrane and forms pores via a complex pathway, which eventually leads to the cell lysis. In this review, we summarize two different pathways in which RTX toxins interact with host cell membrane and discuss the possible reasons for specific and unspecific activity of RTX toxins to different types of host cells.
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Affiliation(s)
- Feby M Chacko
- Institute of Biochemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
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2
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Heterologously secreted MbxA from Moraxella bovis induces a membrane blebbing response of the human host cell. Sci Rep 2022; 12:17825. [PMID: 36280777 PMCID: PMC9592583 DOI: 10.1038/s41598-022-22480-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 10/14/2022] [Indexed: 01/20/2023] Open
Abstract
Many proteins of the Repeats in Toxins (RTX) protein family are toxins of Gram-negative pathogens including hemolysin A (HlyA) of uropathogenic E. coli. RTX proteins are secreted via Type I secretion systems (T1SS) and adopt their native conformation in the Ca2+-rich extracellular environment. Here we employed the E. coli HlyA T1SS as a heterologous surrogate system for the RTX toxin MbxA from the bovine pathogen Moraxella bovis. In E. coli the HlyA system successfully activates the heterologous MbxA substrate by acylation and secretes the precursor proMbxA and active MbxA allowing purification of both species in quantities sufficient for a variety of investigations. The activating E. coli acyltransferase HlyC recognizes the acylation sites in MbxA, but unexpectedly in a different acylation pattern as for its endogenous substrate HlyA. HlyC-activated MbxA shows host species-independent activity including a so-far unknown toxicity against human lymphocytes and epithelial cells. Using live-cell imaging, we show an immediate MbxA-mediated permeabilization and a rapidly developing blebbing of the plasma membrane in epithelial cells, which is associated with immediate cell death.
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Spitz O, Erenburg IN, Kanonenberg K, Peherstorfer S, Lenders MHH, Reiners J, Ma M, Luisi BF, Smits SHJ, Schmitt L. Identity Determinants of the Translocation Signal for a Type 1 Secretion System. Front Physiol 2022; 12:804646. [PMID: 35222063 PMCID: PMC8870123 DOI: 10.3389/fphys.2021.804646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/31/2021] [Indexed: 11/28/2022] Open
Abstract
The toxin hemolysin A was first identified in uropathogenic E. coli strains and shown to be secreted in a one-step mechanism by a dedicated secretion machinery. This machinery, which belongs to the Type I secretion system family of the Gram-negative bacteria, is composed of the outer membrane protein TolC, the membrane fusion protein HlyD and the ABC transporter HlyB. The N-terminal domain of HlyA represents the toxin which is followed by a RTX (Repeats in Toxins) domain harboring nonapeptide repeat sequences and the secretion signal at the extreme C-terminus. This secretion signal, which is necessary and sufficient for secretion, does not appear to require a defined sequence, and the nature of the encoded signal remains unknown. Here, we have combined structure prediction based on the AlphaFold algorithm together with functional and in silico data to examine the role of secondary structure in secretion. Based on the presented data, a C-terminal, amphipathic helix is proposed between residues 975 and 987 that plays an essential role in the early steps of the secretion process.
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Affiliation(s)
- Olivia Spitz
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Isabelle N. Erenburg
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Kerstin Kanonenberg
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sandra Peherstorfer
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Michael H. H. Lenders
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Jens Reiners
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Miao Ma
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Ben F. Luisi
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Sander H. J. Smits
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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Functional Reconstitution of HlyB, a Type I Secretion ABC Transporter, in Saposin-A Nanoparticles. Sci Rep 2019; 9:8436. [PMID: 31182729 PMCID: PMC6558041 DOI: 10.1038/s41598-019-44812-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 05/23/2019] [Indexed: 11/08/2022] Open
Abstract
Type I secretion systems (T1SS) are ubiquitous transport machineries in Gram-negative bacteria. They comprise a relatively simple assembly of three membrane-localised proteins: an inner-membrane complex composed of an ABC transporter and a membrane fusion protein, and a TolC-like outer membrane component. T1SS transport a wide variety of substrates with broad functional diversity. The ABC transporter hemolysin B (HlyB), for example, is part of the hemolysin A-T1SS in Escherichia coli. In contrast to canonical ABC transporters, an accessory domain, a C39 peptidase-like domain (CLD), is located at the N-terminus of HlyB and is essential for secretion. In this study, we have established an optimised purification protocol for HlyB and the subsequent reconstitution employing the saposin-nanoparticle system. We point out the negative influence of free detergent on the basal ATPase activity of HlyB, studied the influence of a lysolipid or lipid matrix on activity and present functional studies with the full-length substrate proHlyA in its folded and unfolded states, which both have a stimulatory effect on the ATPase activity.
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Verma V, Gupta S, Kumar P, Rawat A, Singh Dhanda R, Yadav M. Efficient production of endotoxin depleted bioactive α-hemolysin of uropathogenicEscherichia coli. Prep Biochem Biotechnol 2019; 49:616-622. [DOI: 10.1080/10826068.2019.1591993] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Vivek Verma
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Surbhi Gupta
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Parveen Kumar
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Ankita Rawat
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | | | - Manisha Yadav
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
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Peherstorfer S, Brewitz HH, Paul George AA, Wißbrock A, Adam JM, Schmitt L, Imhof D. Insights into mechanism and functional consequences of heme binding to hemolysin-activating lysine acyltransferase HlyC from Escherichia coli. Biochim Biophys Acta Gen Subj 2018; 1862:1964-1972. [PMID: 29908817 DOI: 10.1016/j.bbagen.2018.06.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 01/01/2023]
Abstract
BACKGROUND Tight regulation of heme homeostasis is a critical mechanism in pathogenic bacteria since heme functions as iron source and prosthetic group, but is also toxic at elevated concentrations. Hemolysin-activating lysine-acyltransferase (HlyC) from Escherichia coli is crucial for maturation of hemolysin A, which lyses several mammalian cells including erythrocytes liberating large amounts of heme for bacterial uptake. A possible impact and functional consequences of the released heme on events employing bacterial HlyC have remained unexplored. METHODS Heme binding to HlyC was investigated using UV/vis and SPR spectroscopy. Functional impact of heme association was examined using an in vitro hemolysis assay. The interaction was further studied by homology modeling, molecular docking and dynamics simulations. RESULTS We identified HlyC as potential heme-binding protein possessing heme-regulatory motifs. Using wild-type protein and a double alanine mutant we demonstrated that heme binds to HlyC via histidine 151 (H151). We could show further that heme inhibits the enzymatic activity of wild-type HlyC. Computational studies illustrated potential interaction sites in addition to H151 confirming the results from spectroscopy indicating more than one heme-binding site. CONCLUSIONS Taken together, our results reveal novel insights into heme-protein interactions and regulation of a component of the heme uptake system in one of the major causative agents of urinary tract infections in humans. GENERAL SIGNIFICANCE This study points to a possible novel mechanism of regulation as present in many uropathogenic E. coli strains at an early stage of heme iron acquisition from erythrocytes for subsequent internalization by the bacterial heme-uptake machinery.
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Affiliation(s)
- Sandra Peherstorfer
- Institute of Biochemistry, University of Düsseldorf, 40255 Düsseldorf, Germany
| | - Hans Henning Brewitz
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany
| | - Ajay Abisheck Paul George
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany
| | - Amelie Wißbrock
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany
| | - Jana Maria Adam
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, University of Düsseldorf, 40255 Düsseldorf, Germany.
| | - Diana Imhof
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany.
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Kanonenberg K, Spitz O, Erenburg IN, Beer T, Schmitt L. Type I secretion system—it takes three and a substrate. FEMS Microbiol Lett 2018; 365:4966979. [DOI: 10.1093/femsle/fny094] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/09/2018] [Indexed: 12/20/2022] Open
Affiliation(s)
- Kerstin Kanonenberg
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Olivia Spitz
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Isabelle N Erenburg
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Tobias Beer
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
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Type I Protein Secretion-Deceptively Simple yet with a Wide Range of Mechanistic Variability across the Family. EcoSal Plus 2017; 7. [PMID: 28084193 DOI: 10.1128/ecosalplus.esp-0019-2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A very large type I polypeptide begins to reel out from a ribosome; minutes later, the still unidentifiable polypeptide, largely lacking secondary structure, is now in some cases a thousand or more residues longer. Synthesis of the final hundred C-terminal residues commences. This includes the identity code, the secretion signal within the last 50 amino acids, designed to dock with a waiting ATP binding cassette (ABC) transporter. What happens next is the subject of this review, with the main, but not the only focus on hemolysin HlyA, an RTX protein toxin secreted by the type I system. Transport substrates range from small peptides to giant proteins produced by many pathogens. These molecules, without detectable cellular chaperones, overcome enormous barriers, crossing two membranes before final folding on the cell surface, involving a unique autocatalytic process.Unfolded HlyA is extruded posttranslationally, C-terminal first. The transenvelope "tunnel" is formed by HlyB (ABC transporter), HlyD (membrane fusion protein) straddling the inner membrane and periplasm and TolC (outer membrane). We present a new evaluation of the C-terminal secretion code, and the structure function of HlyD and HlyB at the heart of this nanomachine. Surprisingly, key details of the secretion mechanism are remarkably variable in the many type I secretion system subtypes. These include alternative folding processes, an apparently distinctive secretion code for each type I subfamily, and alternative forms of the ABC transporter; most remarkably, the ABC protein probably transports peptides or polypeptides by quite different mechanisms. Finally, we suggest a putative structure for the Hly-translocon, HlyB, the multijointed HlyD, and the TolC exit.
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Okegawa Y, Motohashi K. A simple and ultra-low cost homemade seamless ligation cloning extract (SLiCE) as an alternative to a commercially available seamless DNA cloning kit. Biochem Biophys Rep 2015; 4:148-151. [PMID: 29124198 PMCID: PMC5668909 DOI: 10.1016/j.bbrep.2015.09.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 11/27/2022] Open
Abstract
The seamless ligation cloning extract (SLiCE) method is a novel seamless DNA cloning tool that utilizes homologous recombination activities in Escherichia coli cell lysates to assemble DNA fragments into a vector. Several laboratory E. coli strains can be used as a source for the SLiCE extract; therefore, the SLiCE-method is highly cost-effective.The SLiCE has sufficient cloning ability to support conventional DNA cloning, and can simultaneously incorporate two unpurified DNA fragments into vector. Recently, many seamless DNA cloning kits have become commercially available; these are generally very convenient, but expensive. In this study, we evaluated the cloning efficiencies between a simple and highly cost-effective SLiCE-method and a commercial kit under various molar ratios of insert DNA fragments to vector DNA. This assessment identified that the SLiCE from a laboratory E. coli strain yielded 30−85% of the colony formation rate of a commercially available seamless DNA cloning kit. The cloning efficiencies of both methods were highly effective, exhibiting over 80% success rate under all conditions examined. These results suggest that SLiCE from a laboratory E. coli strain can efficiently function as an effective alternative to commercially available seamless DNA cloning kits.
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Affiliation(s)
- Yuki Okegawa
- Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Ken Motohashi
- Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama, Kita-ku, Kyoto 603-8555, Japan
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Abstract
Type 1 secretion systems (T1SS) of Gram-negative bacteria are responsible for the secretion of various proteases, lipases, S-layer proteins or toxins into the extracellular space. The paradigm of these systems is the hemolysin A (HlyA) T1SS of Escherichia coli. This multiple membrane protein complex is able to secrete the toxin HlyA in one step across both E. coli membranes. Common to all secreted T1SS substrates is a C-terminal secretion sequence being necessary as well as sufficient for secretion. However, it is not known whether transport occurs directionally, i.e. the N- or the C-terminus of T1SS substrates is secreted first. We have addressed this question by constructing HlyA fusions with the rapidly folding eGFP resulting in a stalled T1SS. Differential labeling and subsequent fluorescence microscopic detection of C- and N-terminal parts of the fusions allowed us to demonstrate vectorial transport of HlyA through the T1SS with the C-terminus appearing first outside the bacterial cells.
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