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Guilvout I, Samsudin F, Huber RG, Bond PJ, Bardiaux B, Francetic O. Membrane platform protein PulF of the Klebsiella type II secretion system forms a trimeric ion channel essential for endopilus assembly and protein secretion. mBio 2024; 15:e0142323. [PMID: 38063437 PMCID: PMC10790770 DOI: 10.1128/mbio.01423-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/24/2023] [Indexed: 01/17/2024] Open
Abstract
IMPORTANCE Type IV pili and type II secretion systems are members of the widespread type IV filament (T4F) superfamily of nanomachines that assemble dynamic and versatile surface fibers in archaea and bacteria. The assembly and retraction of T4 filaments with diverse surface properties and functions require the plasma membrane platform proteins of the GspF/PilC superfamily. Generally considered dimeric, platform proteins are thought to function as passive transmitters of the mechanical energy generated by the ATPase motor, to somehow promote insertion of pilin subunits into the nascent pilus fibers. Here, we generate and experimentally validate structural predictions that support the trimeric state of a platform protein PulF from a type II secretion system. The PulF trimers form selective proton or sodium channels which might energize pilus assembly using the membrane potential. The conservation of the channel sequence and structural features implies a common mechanism for all T4F assembly systems. We propose a model of the oligomeric PulF-PulE ATPase complex that provides an essential framework to investigate and understand the pilus assembly mechanism.
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Affiliation(s)
- Ingrid Guilvout
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
| | | | | | - Peter J. Bond
- Bioinformatics Institute (A-STAR), Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Structural Bioinformatics Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Bacterial Transmembrane Systems Unit, Paris, France
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
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2
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Li Y, Santos-Moreno J, Francetic O. The periplasmic coiled coil formed by the assembly platform proteins PulL and PulM is critical for function of the Klebsiella type II secretion system. Res Microbiol 2023; 174:104075. [PMID: 37141929 DOI: 10.1016/j.resmic.2023.104075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/06/2023]
Abstract
Bacteria use type II secretion systems (T2SS) to secrete to their surface folded proteins that confer diverse functions, from nutrient acquisition to virulence. In the Klebsiella species, T2SS-mediated secretion of pullulanase (PulA) requires assembly of a dynamic filament called the endopilus. The inner membrane assembly platform (AP) subcomplex is essential for endopilus assembly and PulA secretion. AP components PulL and PulM interact with each other through their C-terminal globular domains and transmembrane segments. Here, we investigated the roles of their periplasmic helices, predicted to form a coiled coil, in assembly and function of the PulL-PulM complex. PulL and PulM variants lacking these periplasmic helices were defective for interaction in the bacterial two-hybrid (BACTH) assay. Their functions in PulA secretion and assembly of PulG subunits into endopilus filaments were strongly reduced. Interestingly, deleting the cytoplasmic peptide of PulM nearly abolished the function of variant PulMΔN and its interaction with PulG, but not with PulL, in the BACTH assay. Nevertheless, PulL was specifically proteolyzed in the presence of the PulMΔN variant, suggesting that PulM N-terminal peptide stabilizes PulL in the cytoplasm. We discuss the implications of these results for the T2S endopilus and type IV pilus assembly mechanisms.
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Affiliation(s)
- Yuanyuan Li
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| | - Javier Santos-Moreno
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
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3
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Abstract
Over the billions of years that bacteria have been around, they have evolved several sophisticated protein secretion nanomachines to deliver toxins, hydrolytic enzymes, and effector proteins into their environments. Of these, the type II secretion system (T2SS) is used by Gram-negative bacteria to export a wide range of folded proteins from the periplasm across the outer membrane.
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Dazzoni R, Li Y, López-Castilla A, Brier S, Mechaly A, Cordier F, Haouz A, Nilges M, Francetic O, Bardiaux B, Izadi-Pruneyre N. Structure and dynamic association of an assembly platform subcomplex of the bacterial type II secretion system. Structure 2023; 31:152-165.e7. [PMID: 36586404 DOI: 10.1016/j.str.2022.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/20/2022] [Accepted: 11/29/2022] [Indexed: 12/31/2022]
Abstract
Type II secretion systems (T2SSs) allow diderm bacteria to secrete hydrolytic enzymes, adhesins, or toxins important for growth and virulence. To promote secretion of folded proteins, T2SSs assemble periplasmic filaments called pseudopili or endopili at an inner membrane subcomplex, the assembly platform (AP). Here, we combined biophysical approaches, nuclear magnetic resonance (NMR) and X-ray crystallography, to study the Klebsiella AP components PulL and PulM. We determined the structure and associations of their periplasmic domains and describe the structure of the heterodimer formed by their ferredoxin-like domains. We show how structural complementarity and plasticity favor their association during the secretion process. Cysteine scanning and crosslinking data provided additional constraints to build a structural model of the PulL-PulM assembly in the cellular context. Our structural and functional insights, together with the relative cellular abundance of its components, support the role of AP as a dynamic hub that orchestrates pilus polymerization.
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Affiliation(s)
- Régine Dazzoni
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France
| | - Yuanyuan Li
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France
| | - Aracelys López-Castilla
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France
| | - Sébastien Brier
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Ariel Mechaly
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Crystallography Platform, 75015 Paris, France
| | - Florence Cordier
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France
| | - Ahmed Haouz
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Crystallography Platform, 75015 Paris, France
| | - Michael Nilges
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Bacterial Transmembrane Systems Unit, 75015 Paris.
| | - Nadia Izadi-Pruneyre
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Bacterial Transmembrane Systems Unit, 75015 Paris.
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5
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Karami Y, López-Castilla A, Ori A, Thomassin JL, Bardiaux B, Malliavin T, Izadi-Pruneyre N, Francetic O, Nilges M. Computational and biochemical analysis of type IV pilus dynamics and stability. Structure 2021; 29:1397-1409.e6. [PMID: 34520738 DOI: 10.1016/j.str.2021.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/14/2021] [Accepted: 07/20/2021] [Indexed: 11/16/2022]
Abstract
Type IV pili (T4P) are distinctive dynamic filaments at the surface of many bacteria that can rapidly extend and retract and withstand strong forces. T4P are important virulence factors in many human pathogens, including Enterohemorrhagic Escherichia coli (EHEC). The structure of the EHEC T4P has been determined by integrating nuclear magnetic resonance (NMR) and cryo-electron microscopy data. To better understand pilus assembly, stability, and function, we performed a total of 108 ms all-atom molecular dynamics simulations of wild-type and mutant T4P. Extensive characterization of the conformational landscape of T4P in different conditions of temperature, pH, and ionic strength is complemented with targeted mutagenesis and biochemical analyses. Our simulations and NMR experiments reveal a conserved set of residues defining a calcium-binding site at the interface between three pilin subunits. Calcium binding enhances T4P stability ex vivo and in vitro, supporting the role of this binding site as a potential pocket for drug design.
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Affiliation(s)
- Yasaman Karami
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Aracelys López-Castilla
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Andrea Ori
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Jenny-Lee Thomassin
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Therese Malliavin
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France.
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6
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Dazzoni R, López-Castilla A, Cordier F, Bardiaux B, Nilges M, Francetic O, Izadi-Pruneyre N. 1H, 15 N and 13C resonance assignments of the C-terminal domain of PulL, a component of the Klebsiella oxytoca type II secretion system. Biomol NMR Assign 2021; 15:455-459. [PMID: 34410621 DOI: 10.1007/s12104-021-10045-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
Type II secretion systems (T2SS) allow Gram-negative bacteria to transport toxins and enzymes from the periplasm to the external milieu, and are thus important for the pathogenicity of bacteria. To drive secretion, T2SS assemble filaments called pseudopili closely related to bacterial type IV pili. These filaments are non-covalent polymers of proteins that are assembled by an inner membrane complex called the assembly platform connected to a cytoplasmic ATPase motor. In the Klebsiella oxytoca T2SS, the PulL protein from the assembly platform is essential for pseudopilus assembly and protein secretion. However, its role in these processes is not well understood. To decipher the molecular basis of PulL function, we used solution NMR to study its structure and interactions with other components of the machinery. Here as a first step, we report the 1H, 15 N and 13C backbone and side-chain chemical shift assignments of the C-terminal periplasmic domain of PulL and its secondary structure based on NMR data.
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Affiliation(s)
- Régine Dazzoni
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Aracelys López-Castilla
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Florence Cordier
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
- Biological NMR Technological Platform, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France.
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7
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Horváthová L, Žárský V, Pánek T, Derelle R, Pyrih J, Motyčková A, Klápšťová V, Vinopalová M, Marková L, Voleman L, Klimeš V, Petrů M, Vaitová Z, Čepička I, Hryzáková K, Harant K, Gray MW, Chami M, Guilvout I, Francetic O, Franz Lang B, Vlček Č, Tsaousis AD, Eliáš M, Doležal P. Analysis of diverse eukaryotes suggests the existence of an ancestral mitochondrial apparatus derived from the bacterial type II secretion system. Nat Commun 2021; 12:2947. [PMID: 34011950 PMCID: PMC8134430 DOI: 10.1038/s41467-021-23046-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 03/22/2021] [Indexed: 12/14/2022] Open
Abstract
The type 2 secretion system (T2SS) is present in some Gram-negative eubacteria and used to secrete proteins across the outer membrane. Here we report that certain representative heteroloboseans, jakobids, malawimonads and hemimastigotes unexpectedly possess homologues of core T2SS components. We show that at least some of them are present in mitochondria, and their behaviour in biochemical assays is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). We additionally identified 23 protein families co-occurring with miT2SS in eukaryotes. Seven of these proteins could be directly linked to the core miT2SS by functional data and/or sequence features, whereas others may represent different parts of a broader functional pathway, possibly also involving the peroxisome. Its distribution in eukaryotes and phylogenetic evidence together indicate that the miT2SS-centred pathway is an ancestral eukaryotic trait. Our findings thus have direct implications for the functional properties of the early mitochondrion. Bacteria use the type 2 secretion system to secrete enzymes and toxins across the outer membrane to the environment. Here the authors analyse the T2SS pathway in three protist lineages and suggest that the early mitochondrion may have been capable of secreting proteins into the cytosol.
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Affiliation(s)
- Lenka Horváthová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vojtěch Žárský
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Tomáš Pánek
- Faculty of Science, Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic.,Faculty of Science, Department of Zoology, Charles University, Prague 2, Czech Republic
| | - Romain Derelle
- School of Biosciences, University of Birmingham, Edgbaston, UK
| | - Jan Pyrih
- Laboratory of Molecular & Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, UK.,Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Alžběta Motyčková
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Veronika Klápšťová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Martina Vinopalová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Lenka Marková
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Luboš Voleman
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vladimír Klimeš
- Faculty of Science, Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic
| | - Markéta Petrů
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Zuzana Vaitová
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic
| | - Ivan Čepička
- Faculty of Science, Department of Zoology, Charles University, Prague 2, Czech Republic
| | - Klára Hryzáková
- Faculty of Science, Department of Genetics and Microbiology, Charles University, Prague 2, Czech Republic
| | - Karel Harant
- Faculty of Science, Proteomic core facility, Charles University, BIOCEV, Vestec, Czech Republic
| | - Michael W Gray
- Department of Biochemistry and Molecular Biology and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada
| | - Mohamed Chami
- Center for Cellular Imaging and NanoAnalytics, University of Basel, Basel, Switzerland
| | - Ingrid Guilvout
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - B Franz Lang
- Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montreal, QC, Canada
| | - Čestmír Vlček
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague 4, Czech Republic
| | - Anastasios D Tsaousis
- Laboratory of Molecular & Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, UK
| | - Marek Eliáš
- Faculty of Science, Department of Biology and Ecology, University of Ostrava, Ostrava, Czech Republic.
| | - Pavel Doležal
- Faculty of Science, Department of Parasitology, Charles University, BIOCEV, Vestec, Czech Republic.
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8
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Karami Y, Francetic O, Izadi Pruneyre N, Nilges M. Deciphering the Conformational Dynamics of Escherichia coli Type IV Pilus. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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9
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Jacobsen T, Bardiaux B, Francetic O, Izadi-Pruneyre N, Nilges M. Structure and function of minor pilins of type IV pili. Med Microbiol Immunol 2019; 209:301-308. [PMID: 31784891 PMCID: PMC7248040 DOI: 10.1007/s00430-019-00642-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/14/2019] [Indexed: 02/06/2023]
Abstract
Type IV pili are versatile and highly flexible fibers formed on the surface of many Gram-negative and Gram-positive bacteria. Virulence and infection rate of several pathogenic bacteria, such as Neisseria meningitidis and Pseudomonas aeruginosa, are strongly dependent on the presence of pili as they facilitate the adhesion of the bacteria to the host cell. Disruption of the interactions between the pili and the host cells by targeting proteins involved in this interaction could, therefore, be a treatment strategy. A type IV pilus is primarily composed of multiple copies of protein subunits called major pilins. Additional proteins, called minor pilins, are present in lower abundance, but are essential for the assembly of the pilus or for its specific functions. One class of minor pilins is required to initiate the formation of pili, and may form a complex similar to that identified in the related type II secretion system. Other, species-specific minor pilins in the type IV pilus system have been shown to promote additional functions such as DNA binding, aggregation and adherence. Here, we will review the structure and the function of the minor pilins from type IV pili.
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Affiliation(s)
- Theis Jacobsen
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France.,Sorbonne Université, Complexité du Vivant, 75005, Paris, France
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France.
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10
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Bardiaux B, de Amorim GC, Luna Rico A, Zheng W, Guilvout I, Jollivet C, Nilges M, Egelman EH, Izadi-Pruneyre N, Francetic O. Structure and Assembly of the Enterohemorrhagic Escherichia coli Type 4 Pilus. Structure 2019; 27:1082-1093.e5. [PMID: 31056419 PMCID: PMC7003672 DOI: 10.1016/j.str.2019.03.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/18/2019] [Accepted: 03/25/2019] [Indexed: 12/30/2022]
Abstract
Bacterial type 4a pili are dynamic surface filaments that promote bacterial adherence, motility, and macromolecular transport. Their genes are highly conserved among enterobacteria and their expression in enterohemorrhagic Escherichia coli (EHEC) promotes adhesion to intestinal epithelia and pro-inflammatory signaling. To define the molecular basis of EHEC pilus assembly, we determined the structure of the periplasmic domain of its major subunit PpdD (PpdDp), a prototype of an enterobacterial pilin subfamily containing two disulfide bonds. The structure of PpdDp, determined by NMR, was then docked into the density envelope of purified EHEC pili obtained by cryoelectron microscopy (cryo-EM). Cryo-EM reconstruction of EHEC pili at ∼8 Å resolution revealed extremely high pilus flexibility correlating with a large extended region of the pilin stem. Systematic mutagenesis combined with functional and interaction analyses identified charged residues essential for pilus assembly. Structural information on exposed regions and interfaces between EHEC pilins is relevant for vaccine and drug discovery.
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Affiliation(s)
- Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France
| | - Gisele Cardoso de Amorim
- NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Areli Luna Rico
- NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Ingrid Guilvout
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Camille Jollivet
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France; NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France.
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France.
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11
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Abstract
Bacterial surface appendages of the type 4 pilus superfamily play diverse roles in adherence, aggregation, motility, signaling, and macromolecular transport. Here we describe two analytical approaches to study assembly of type 4 pili and of pseudopili produced by type 2 protein secretion systems: the shearing assay and immunofluorescence microscopy. These complementary antibody-based methods allow for semiquantitative analysis of fiber assembly. The shearing assay can be scaled up to yield crude extracts of pili that can be further analyzed by electron and atomic force microscopy or by mass spectrometry.
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Affiliation(s)
- Areli Luna-Rico
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris Cedex 15, France
| | - Jenny-Lee Thomassin
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris Cedex 15, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris Cedex 15, France.
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12
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Luna Rico A, Zheng W, Petiot N, Egelman EH, Francetic O. Functional reconstitution of the type IVa pilus assembly system from enterohaemorrhagic Escherichia coli. Mol Microbiol 2019; 111:732-749. [PMID: 30561149 DOI: 10.1111/mmi.14188] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2018] [Indexed: 12/17/2022]
Abstract
Type 4a pili (T4aP) are long, thin and dynamic fibres displayed on the surface of diverse bacteria promoting adherence, motility and transport functions. Genomes of many Enterobacteriaceae contain conserved gene clusters encoding putative T4aP assembly systems. However, their expression has been observed only in few strains including Enterohaemorrhagic Escherichia coli (EHEC) and their inducers remain unknown. Here we used EHEC genomic DNA as a template to amplify and assemble an artificial operon composed of four gene clusters encoding 13 pilus assembly proteins. Controlled expressions of this operon in nonpathogenic E. coli strains led to efficient assembly of T4aP composed of the major pilin PpdD, as shown by shearing assays and immunofluorescence microscopy. When compared with PpdD pili assembled in a heterologous Klebsiella T2SS type 2 secretion system (T2SS) by using cryo-electron microscopy (cryoEM), these pili showed indistinguishable helical parameters, emphasizing that major pilins are the principal determinants of the fibre structure. Bacterial two-hybrid analysis identified several interactions of PpdD with T4aP assembly proteins, and with components of the T2SS that allow for heterologous fibre assembly. These studies lay ground for further characterization of the T4aP structure, function and biogenesis in enterobacteria.
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Affiliation(s)
- Areli Luna Rico
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, Paris, 75724, France.,Structural Bioinformatics Unit and NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, Paris, 75724, France
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22908, USA
| | - Nathalie Petiot
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, Paris, 75724, France
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22908, USA
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, Paris, 75724, France
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13
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Collet C, Thomassin JL, Francetic O, Genevaux P, Tran Van Nhieu G. Protein polarization driven by nucleoid exclusion of DnaK(HSP70)-substrate complexes. Nat Commun 2018; 9:2027. [PMID: 29795186 PMCID: PMC5966378 DOI: 10.1038/s41467-018-04414-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 04/23/2018] [Indexed: 11/18/2022] Open
Abstract
Many bacterial proteins require specific subcellular localization for function. How Escherichia coli proteins localize at one pole, however, is still not understood. Here, we show that the DnaK (HSP70) chaperone controls unipolar localization of the Shigella IpaC type III secretion substrate. While preventing the formation of lethal IpaC aggregates, DnaK promoted the incorporation of IpaC into large and dynamic complexes (LDCs) restricted at the bacterial pole through nucleoid occlusion. Unlike stable polymers and aggregates, LDCs show dynamic behavior indicating that nucleoid occlusion also applies to complexes formed through transient interactions. Fluorescence recovery after photobleaching analysis shows DnaK-IpaC exchanges between opposite poles and DnaKJE-mediated incorporation of immature substrates in LDCs. These findings reveal a key role for LDCs as reservoirs of functional DnaK-substrates that can be rapidly mobilized for secretion triggered upon bacterial contact with host cells. Many bacterial proteins exhibit spatially defined localization important for function. Here the authors show that the polar localization of Shigella IpaC type III secretion substrate is mediated by its interaction with the DnaK chaperone and occlusion by the bacterial nucleoid.
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Affiliation(s)
- Clémence Collet
- Equipe Communication Intercellulaire et Infections Microbiennes. Centre de Recherche Interdisciplinaire en Biologie (CIRB). Collège de France, 11, Place Marcelin Berthelot, 75005, Paris, France.,Institut National de la Santé et de la Recherche Médicale (Inserm) U1050, Paris, Cedex 15, France.,Centre National de la Recherche Scientifique (CNRS) UMR7241, 75016, Paris, France.,MEMOLIFE Laboratory of excellence and Paris Science Lettre, Paris, Cedex 15, France
| | - Jenny-Lee Thomassin
- Equipe Communication Intercellulaire et Infections Microbiennes. Centre de Recherche Interdisciplinaire en Biologie (CIRB). Collège de France, 11, Place Marcelin Berthelot, 75005, Paris, France.,Institut National de la Santé et de la Recherche Médicale (Inserm) U1050, Paris, Cedex 15, France.,Centre National de la Recherche Scientifique (CNRS) UMR7241, 75016, Paris, France.,MEMOLIFE Laboratory of excellence and Paris Science Lettre, Paris, Cedex 15, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Institut Pasteur, Department of Structural Biology and Chemistry, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, Cedex 15, France
| | - Pierre Genevaux
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, 118 route de Narbonne, 31062, Toulouse, Cedex 9, France
| | - Guy Tran Van Nhieu
- Equipe Communication Intercellulaire et Infections Microbiennes. Centre de Recherche Interdisciplinaire en Biologie (CIRB). Collège de France, 11, Place Marcelin Berthelot, 75005, Paris, France. .,Institut National de la Santé et de la Recherche Médicale (Inserm) U1050, Paris, Cedex 15, France. .,Centre National de la Recherche Scientifique (CNRS) UMR7241, 75016, Paris, France. .,MEMOLIFE Laboratory of excellence and Paris Science Lettre, Paris, Cedex 15, France.
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14
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Lopez-Castilla A, Bardiaux B, Thomassin JL, Zheng W, Nilges M, Egelman E, Francetic O, Izadi Pruneyre N. Integrative Structural Biology of the Calcium Dependent Type 2 Secretion Pseudopilus. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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15
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Spaulding CN, Schreiber HL, Zheng W, Dodson KW, Hazen JE, Conover MS, Wang F, Svenmarker P, Luna-Rico A, Francetic O, Andersson M, Hultgren S, Egelman EH. Functional role of the type 1 pilus rod structure in mediating host-pathogen interactions. eLife 2018; 7:31662. [PMID: 29345620 PMCID: PMC5798934 DOI: 10.7554/elife.31662] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 01/12/2018] [Indexed: 12/11/2022] Open
Abstract
Uropathogenic E. coli (UPEC), which cause urinary tract infections (UTI), utilize type 1 pili, a chaperone usher pathway (CUP) pilus, to cause UTI and colonize the gut. The pilus rod, comprised of repeating FimA subunits, provides a structural scaffold for displaying the tip adhesin, FimH. We solved the 4.2 Å resolution structure of the type 1 pilus rod using cryo-electron microscopy. Residues forming the interactive surfaces that determine the mechanical properties of the rod were maintained by selection based on a global alignment of fimA sequences. We identified mutations that did not alter pilus production in vitro but reduced the force required to unwind the rod. UPEC expressing these mutant pili were significantly attenuated in bladder infection and intestinal colonization in mice. This study elucidates an unappreciated functional role for the molecular spring-like property of type 1 pilus rods in host-pathogen interactions and carries important implications for other pilus-mediated diseases. Escherichia coli, or E. coli for short, is a type of bacteria commonly found in the guts of people and animals. Certain types of E. coli can cause urinary tract infections (UTIs): they travel from the digestive tract up to the bladder (and sometimes to the kidneys) where they provoke painful symptoms. To cause the infection, the bacteria must become solidly attached to the lining of the bladder; otherwise they will get flushed out whenever urine is expelled. Pili are hair-like structures that cover a bacterium and allow it to attach to surfaces. E. coli has many different types of pili, but one seems particularly important in UTIs: type 1 pili. These pili are formed of subunits that assemble into a long coil-shaped rod, which is tipped by adhesive molecules that can stick to body surfaces. The current hypothesis is that the pili act as shock absorbers: when the bladder empties, the pili’s coil-like structure can unwind into a flexible straight fiber. This would take some of the forces off the adhesive molecules that are attached to the bladder, and help the bacteria to remain in place when urine flows out. However, the exact structure of type 1 pili is still unclear, and the essential role of their coil-like shape unconfirmed. Here, Spaulding, Schreiber, Zheng et al. use a microscopy method called cryo-EM to reveal the structure of the type 1 pili at near atomic-level, and identify the key units necessary for their coiling properties. The experiments show that pili with certain mutations in these units unwind much more easily when the bacteria carrying them are ‘tugged on’ with molecular tweezers. The bacteria with mutant pili are also less able to cause UTIs in mice. The coiling ability of the type 1 pili is therefore essential for E. coli to invade and colonize the bladder. Every year, over 150 million people worldwide experience a UTI; for 25% of women, the infection regularly returns. Antibiotics usually treat the problem but bacteria are becoming resistant to these drugs. New treatments could be designed if scientists understand what roles pili play in the infection mechanisms.
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Affiliation(s)
- Caitlin N Spaulding
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, United States
| | - Henry Louis Schreiber
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, United States
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, United States
| | - Karen W Dodson
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, United States
| | - Jennie E Hazen
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, United States
| | - Matt S Conover
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, United States
| | - Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, United States
| | | | - Areli Luna-Rico
- Department of Structural Biology and Chemistry, Institut Pasteur, Biochemistry of Macromolecular Interactions Unit, Paris, France
| | - Olivera Francetic
- Department of Structural Biology and Chemistry, Institut Pasteur, Biochemistry of Macromolecular Interactions Unit, Paris, France
| | | | - Scott Hultgren
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, United States
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, United States
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16
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Nivaskumar M, Francetic O. Unraveling the structural dynamics of the Type II secretion system. Acta Crystallogr A Found Adv 2017. [DOI: 10.1107/s2053273317084947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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17
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López-Castilla A, Vitorge B, Khoury L, Morellet N, Francetic O, Izadi-Pruneyre N. 1H, 15N and 13C resonance assignments and secondary structure of PulG, the major pseudopilin from Klebsiella oxytoca type 2 secretion system. Biomol NMR Assign 2017; 11:155-158. [PMID: 28258547 DOI: 10.1007/s12104-017-9738-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/24/2017] [Indexed: 06/06/2023]
Abstract
Bacteria use complex transporters to secrete functionally relevant proteins to the extracellular medium. The type 2 secretion system (T2SS) translocates folded proteins involved in bacterial nutrient acquisition, virulence and adaptation. The T2SS pseudopilus is a periplasmic filament, assembled by the polymerization of PulG subunits, the major pseudopilin. Pseudopilin proteins have a conserved N-terminal hydrophobic segment followed by a more variable C-terminal periplasmic and globular domain. To better understand the mechanism of assembly and function of the T2SS, we have been studying the structure and dynamics of PulG by NMR, as well as its interaction with other components of the secretion machinery. As a first step on this study, here we reported the chemical shift assignments of PulG C-terminal domain and its secondary structure prediction based on NMR data.
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Affiliation(s)
- Aracelys López-Castilla
- Unité de RMN des Biomolécules, Département de Biologie Structurale et Chimie, Institut Pasteur, 28, rue du Dr Roux, Paris, France.
- CNRS UMR 3528, Paris, France.
| | - Bruno Vitorge
- Unité de RMN des Biomolécules, Département de Biologie Structurale et Chimie, Institut Pasteur, 28, rue du Dr Roux, Paris, France
- CNRS UMR 3528, Paris, France
| | - Léa Khoury
- Unité de RMN des Biomolécules, Département de Biologie Structurale et Chimie, Institut Pasteur, 28, rue du Dr Roux, Paris, France
- CNRS UMR 3528, Paris, France
| | - Nelly Morellet
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Université Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France
| | - Olivera Francetic
- Laboratoire des Systèmes Macromoléculaires et Signalisation, Institut Pasteur, 25 rue du Dr Roux, Paris, France
| | - Nadia Izadi-Pruneyre
- Unité de RMN des Biomolécules, Département de Biologie Structurale et Chimie, Institut Pasteur, 28, rue du Dr Roux, Paris, France.
- CNRS UMR 3528, Paris, France.
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18
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Abstract
Bacteria have acquired multiple systems to expose proteins on their surface, release them in the extracellular environment or even inject them into a neighboring cell. Protein secretion has a high adaptive value and secreted proteins are implicated in many functions, which are often essential for bacterial fitness. Several secreted proteins or secretion machineries have been extensively studied as potential drug targets. It is therefore important to identify the secretion substrates, to understand how they are specifically recognized by the secretion machineries, and how transport through these machineries occurs. The purpose of this review is to provide an overview of the biochemical, genetic and imaging tools that have been developed to evaluate protein secretion in a qualitative or quantitative manner. After a brief overview of the different tools available, we will illustrate their advantages and limitations through a discussion of some of the current open questions related to protein secretion. We will start with the question of the identification of secreted proteins, which for many bacteria remains a critical initial step toward a better understanding of their interactions with the environment. We will then illustrate our toolbox by reporting how these tools have been applied to better understand how substrates are recognized by their cognate machinery, and how secretion proceeds. Finally, we will highlight recent approaches that aim at investigating secretion in real time, and in complex environments such as a tissue or an organism.
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Affiliation(s)
- Benoit Maffei
- Unité de Biologie Cellulaire de l'Infection Microbienne, Institut PasteurParis, France.,Centre National de la Recherche Scientifique UMR3691Paris, France
| | - Olivera Francetic
- Unité de Biochimie des Interactions Macromoléculaires, Institut PasteurParis, France.,Centre National de la Recherche Scientifique ERL6002Paris, France
| | - Agathe Subtil
- Unité de Biologie Cellulaire de l'Infection Microbienne, Institut PasteurParis, France.,Centre National de la Recherche Scientifique UMR3691Paris, France
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19
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Thomassin JL, Santos Moreno J, Guilvout I, Tran Van Nhieu G, Francetic O. The trans-envelope architecture and function of the type 2 secretion system: new insights raising new questions. Mol Microbiol 2017; 105:211-226. [DOI: 10.1111/mmi.13704] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Jenny-Lee Thomassin
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Javier Santos Moreno
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité; Paris France
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Ingrid Guilvout
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Guy Tran Van Nhieu
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Olivera Francetic
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
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20
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Santos-Moreno J, East A, Guilvout I, Nadeau N, Bond PJ, Tran Van Nhieu G, Francetic O. Polar N-terminal Residues Conserved in Type 2 Secretion Pseudopilins Determine Subunit Targeting and Membrane Extraction Steps during Fibre Assembly. J Mol Biol 2017; 429:1746-1765. [PMID: 28427876 DOI: 10.1016/j.jmb.2017.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/10/2017] [Accepted: 04/10/2017] [Indexed: 11/28/2022]
Abstract
Bacterial type 2 secretion systems (T2SS), type 4 pili, and archaeal flagella assemble fibres from initially membrane-embedded pseudopilin and pilin subunits. Fibre subunits are made as precursors with positively charged N-terminal anchors, whose cleavage via the prepilin peptidase, essential for pilin membrane extraction and assembly, is followed by N-methylation of the mature (pseudo)pilin N terminus. The conserved Glu residue at position 5 (E5) of mature (pseudo)pilins is essential for assembly. Unlike T4 pilins, where E5 residue substitutions also abolish N-methylation, the E5A variant of T2SS pseudopilin PulG remains N-methylated but is affected in interaction with the T2SS component PulM. Here, biochemical and functional analyses showed that the PulM interaction defect only partly accounts for the PulGE5A assembly defect. First, PulGT2A variant, equally defective in PulM interaction, remained partially functional. Furthermore, pseudopilus assembly defect of pulG(E5A) mutant was stronger than that of the pulM deletion mutant. To understand the dominant effect of E5A mutation, we used molecular dynamics simulations of PulGE5A, methylated PulGWT (MePulGWT), and MePulGE5A variant in a model membrane. These simulations pointed to a key role for an intramolecular interaction between the pseudopilin N-terminal amine and E5 to limit polar interactions with membrane phospholipids. N-methylation of the N-terminal amine further limited its interactions with phospholipid head-groups to facilitate pseudopilin membrane escape. By binding to polar residues in the conserved N-terminal region of PulG, we propose that PulM acts as chaperone to promote pseudopilin recruitment and coordinate its membrane extraction with subsequent steps of the fibre assembly process.
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Affiliation(s)
- Javier Santos-Moreno
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité, 11 Place Marcelin Berthelot, 75231 Paris, France; Laboratory of Intercellular Communication and Microbial Infections, CIRB, Collège de France, 75231 Paris, France; Institut National de la Santé et de la Recherche Médicale (Inserm) U1050, 75231 Paris, France; Centre National de la Recherche Scientifique (CNRS), UMR7241, 75231 Paris, France; MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres, 75231 Paris, France
| | - Alexandra East
- Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Ingrid Guilvout
- Laboratory of Macromolecular Systems and Signalling, Institut Pasteur, Department of Microbiology and CNRS ERL6002, 25 rue du Dr Roux, 75724 Paris, Cedex 15, France; Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris, Cedex 15, France
| | - Nathalie Nadeau
- Laboratory of Macromolecular Systems and Signalling, Institut Pasteur, Department of Microbiology and CNRS ERL6002, 25 rue du Dr Roux, 75724 Paris, Cedex 15, France
| | - Peter J Bond
- Bioinformatics Institute (A*STAR), 30 Biopolis Str, #07-01 Matrix, Singapore 138671, Singapore; Department of Biological Sciences, Faculty of Science, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Guy Tran Van Nhieu
- Laboratory of Intercellular Communication and Microbial Infections, CIRB, Collège de France, 75231 Paris, France; Institut National de la Santé et de la Recherche Médicale (Inserm) U1050, 75231 Paris, France; Centre National de la Recherche Scientifique (CNRS), UMR7241, 75231 Paris, France; MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres, 75231 Paris, France
| | - Olivera Francetic
- Laboratory of Macromolecular Systems and Signalling, Institut Pasteur, Department of Microbiology and CNRS ERL6002, 25 rue du Dr Roux, 75724 Paris, Cedex 15, France; Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris, Cedex 15, France.
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21
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Guilvout I, Brier S, Chami M, Hourdel V, Francetic O, Pugsley AP, Chamot-Rooke J, Huysmans GHM. Prepore Stability Controls Productive Folding of the BAM-independent Multimeric Outer Membrane Secretin PulD. J Biol Chem 2016; 292:328-338. [PMID: 27903652 DOI: 10.1074/jbc.m116.759498] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/21/2016] [Indexed: 12/19/2022] Open
Abstract
Members of a group of multimeric secretion pores that assemble independently of any known membrane-embedded insertase in Gram-negative bacteria fold into a prepore before membrane-insertion occurs. The mechanisms and the energetics that drive the folding of these proteins are poorly understood. Here, equilibrium unfolding and hydrogen/deuterium exchange monitored by mass spectrometry indicated that a loss of 4-5 kJ/mol/protomer in the N3 domain that is peripheral to the membrane-spanning C domain in the dodecameric secretin PulD, the founding member of this class, prevents pore formation by destabilizing the prepore into a poorly structured dodecamer as visualized by electron microscopy. Formation of native PulD-multimers by mixing protomers that differ in N3 domain stability, suggested that the N3 domain forms a thermodynamic seal onto the prepore. This highlights the role of modest free energy changes in the folding of pre-integration forms of a hyperstable outer membrane complex and reveals a key driving force for assembly independently of the β-barrel assembly machinery.
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Affiliation(s)
- Ingrid Guilvout
- From the Molecular Genetics Unit, CNRS ERL 3526.,Laboratory of Macromolecular Systems and Signaling and
| | - Sébastien Brier
- Structural Mass Spectrometry and Proteomics Unit, CNRS UMR 3528, Institut Pasteur, 75724 Paris Cedex 15, France and
| | - Mohamed Chami
- the BioEM lab, Biozentrum, University of Basel, CH 4058 Basel, Switzerland
| | - Véronique Hourdel
- Structural Mass Spectrometry and Proteomics Unit, CNRS UMR 3528, Institut Pasteur, 75724 Paris Cedex 15, France and
| | - Olivera Francetic
- From the Molecular Genetics Unit, CNRS ERL 3526.,Laboratory of Macromolecular Systems and Signaling and
| | | | - Julia Chamot-Rooke
- Structural Mass Spectrometry and Proteomics Unit, CNRS UMR 3528, Institut Pasteur, 75724 Paris Cedex 15, France and
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22
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Nivaskumar M, Santos-Moreno J, Malosse C, Nadeau N, Chamot-Rooke J, Tran Van Nhieu G, Francetic O. Pseudopilin residue E5 is essential for recruitment by the type 2 secretion system assembly platform. Mol Microbiol 2016; 101:924-41. [DOI: 10.1111/mmi.13432] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Mangayarkarasi Nivaskumar
- Department of Microbiology, Laboratory of Macromolecular Systems and Signalling; Institut Pasteur, CNRS ERL3526; 25 rue du Dr Roux 75724 Paris, Cedex 15 France
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité
| | - Javier Santos-Moreno
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre; France
| | - Christian Malosse
- Structural Mass spectrometry and Proteomics unit; CNRS UMR3528, Institut Pasteur; Paris France
| | - Nathalie Nadeau
- Department of Microbiology, Laboratory of Macromolecular Systems and Signalling; Institut Pasteur, CNRS ERL3526; 25 rue du Dr Roux 75724 Paris, Cedex 15 France
| | - Julia Chamot-Rooke
- Structural Mass spectrometry and Proteomics unit; CNRS UMR3528, Institut Pasteur; Paris France
| | - Guy Tran Van Nhieu
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre; France
| | - Olivera Francetic
- Department of Microbiology, Laboratory of Macromolecular Systems and Signalling; Institut Pasteur, CNRS ERL3526; 25 rue du Dr Roux 75724 Paris, Cedex 15 France
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East A, Mechaly A, Huysmans G, Bernarde C, Tello-Manigne D, Nadeau N, Pugsley A, Buschiazzo A, Alzari P, Bond P, Francetic O. Structural Basis of Pullulanase Membrane Binding and Secretion Revealed by X-Ray Crystallography, Molecular Dynamics and Biochemical Analysis. Structure 2016; 24:92-104. [DOI: 10.1016/j.str.2015.10.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/23/2015] [Accepted: 10/26/2015] [Indexed: 10/22/2022]
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Amorim GC, Cisneros DA, Delepierre M, Francetic O, Izadi-Pruneyre N. ¹H, ¹⁵N and ¹³C resonance assignments of PpdD, a type IV pilin from enterohemorrhagic Escherichia coli. Biomol NMR Assign 2014; 8:43-46. [PMID: 23242787 DOI: 10.1007/s12104-012-9449-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 12/04/2012] [Indexed: 06/01/2023]
Abstract
Bacterial type 4 pili (T4P) are long flexible fibers involved in adhesion, DNA uptake, phage transduction, aggregation and a flagella-independent movement called "twitching motility". T4P comprise thousands of copies of the major pilin subunit, which is initially inserted in the plasma membrane, processed and assembled into dynamic helical filaments. T4P are crucial for host colonization and virulence of many Gram-negative bacteria. In enterohemorrhagic Escherichia coli the T4P, called hemorrhagic coli pili (HCP) promote cell adhesion, motility, biofilm formation and signaling. To understand the mechanism of HCP assembly and function, we analyzed the structure of the major subunit prepilin peptidase-dependent protein D (PpdD) (also called HcpA), a 15 kDa pilin with two potential disulfide bonds. Here we present the (1)H, (15)N and (13)C backbone and side chain resonance assignments of the C-terminal globular domain of PpdD as a first step to its structural determination.
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Affiliation(s)
- Gisele C Amorim
- Unité de RMN des Biomolécules, Département de Biologie Structurale et Chimie, Institut Pasteur, 28, rue du Dr Roux, 75724, Paris Cedex 15, France,
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Cisneros DA, Pehau-Arnaudet G, Francetic O. Heterologous assembly of type IV pili by a type II secretion system reveals the role of minor pilins in assembly initiation. Mol Microbiol 2012; 86:805-18. [PMID: 23006128 DOI: 10.1111/mmi.12033] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2012] [Indexed: 12/16/2022]
Abstract
In Gram-negative bacteria, type IV pilus assembly (T4PS) and type II secretion (T2SS) systems polymerize inner membrane proteins called major pilins or pseudopilins respectively, into thin filaments. Four minor pilins are required in both systems for efficient fibre assembly. Escherichia coli K-12 has a set of T4PS assembly genes that are silent under standard growth conditions. We studied the heterologous assembly of the E. coli type IV pilin PpdD by the Klebsiella oxytoca T2SS called the Pul system. PpdD pilus assembly in this context depended on the expression of the K. oxytoca minor pseudopilin genes pulHIJK or of the E. coli minor pilin genes ppdAB-ygdB-ppdC. The E. coli minor pilins restored assembly of the major pseudopilin PulG in a pulHIJK mutant, but not the secretion of the T2SS substrate pullulanase. Thus, minor pilins and minor pseudopilins are functionally interchangeable in initiating major pilin assembly, further extending the fundamental similarities between the two systems. The data suggest that, in both systems, minor pilins activate the assembly machinery through a common self-assembly mechanism. When produced together, PulG and PpdD assembled into distinct homopolymers, establishing major pilins as key determinants of pilus elongation and structure.
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Affiliation(s)
- David A Cisneros
- Molecular Genetics Unit, Department of Microbiology, Institut Pasteur, 75015, Paris, France
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You C, Sekowska A, Francetic O, Martin-Verstraete I, Wang Y, Danchin A. Spx mediates oxidative stress regulation of the methionine sulfoxide reductases operon in Bacillus subtilis. BMC Microbiol 2008; 8:128. [PMID: 18662407 PMCID: PMC2518928 DOI: 10.1186/1471-2180-8-128] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 07/28/2008] [Indexed: 11/10/2022] Open
Abstract
Background All aerobically grown living cells are exposed to oxidative damage by reactive oxygen species (ROS). A major damage by ROS to proteins is caused by covalent modifications of methionine residues giving methionine sulfoxide (Met-SO). Methionine sulfoxide reductases are enzymes able to regenerate methionine and restore protein function after oxidative damage. Results We characterized the methionine sulfoxide reductase genes msrA and msrB in Bacillus subtilis, forming an operon transcribed from a single sigma A-dependent promoter. The msrAB operon was specifically induced by oxidative stress caused by paraquat (PQ) but not by H2O2. Spx, a global oxidative stress regulator in B. subtilis, is primarily responsible for this PQ-specific induction of msrAB expression. In support of this finding, an spx deletion mutant is extremely sensitive to PQ, and increased expression of msrA was identified in a clpX mutant in which Spx accumulated. However, the Spx effect was also visible under conditions where the protein did not accumulate (PQ treatment), suggesting a specific molecular effect at the level of the Spx protein. Indeed, the CXXC motif of Spx was found essential for its function in the PQ-specific induction of msrAB expression. PQ caused a modification of Spx requiring at least one of the cysteines of the CXXC motif of Spx. The PQ modified form of Spx showed a dynamic change in vivo. Conclusion The Spx mediated PQ-specific regulation pathway of the msrAB operon in B. subtilis is reported. Our results suggest that PQ induced the expression of msrAB partially through an oxidation on Spx via modification of its CXXC motif.
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Affiliation(s)
- CongHui You
- Institut Pasteur, Unité de Génétique des Génomes Bactériens, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France.
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Xicohtencatl-Cortes J, Monteiro-Neto V, Ledesma MA, Jordan DM, Francetic O, Kaper JB, Puente JL, Girón JA. Intestinal adherence associated with type IV pili of enterohemorrhagic Escherichia coli O157:H7. J Clin Invest 2008; 117:3519-29. [PMID: 17948128 DOI: 10.1172/jci30727] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 08/13/2007] [Indexed: 12/24/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic colitis and hemolytic uremic syndrome (HUS) by colonizing the gut mucosa and producing Shiga toxins (Stx). The only factor clearly demonstrated to play a role in EHEC adherence to intestinal epithelial cells is intimin, which binds host cell integrins and nucleolin, as well as a receptor (Tir) that it injects into the host cell. Here we report that EHEC O157:H7 produces adhesive type IV pili, which we term hemorrhagic coli pilus (HCP), composed of a 19-kDa pilin subunit (HcpA) that is encoded by the hcpA chromosomal gene. HCP were observed as bundles of fibers greater than 10 microm in length that formed physical bridges between bacteria adhering to human and bovine host cells. Sera of HUS patients, but not healthy individuals, recognized HcpA, suggesting that the pili are produced in vivo during EHEC infections. Inactivation of the hcpA gene in EHEC EDL933 resulted in significantly reduced adherence to cultured human intestinal and bovine renal epithelial cells and to porcine and bovine gut explants. An escN mutant, which is unable to translocate Tir, adhered less than the hcpA mutant, suggesting that adherence mediated by intimin-Tir interactions is a prelude to HCP-mediated adherence. An hcpA and stx1,2 triple mutant and an hcpA mutant had similar levels of adherence to bovine and human epithelial cells while a stx1,2 double mutant had only a minor defect in adherence, indicating that HCP-mediated adherence and cytotoxicity are independent events. Our data establish that EHEC O157:H7 HCP are intestinal colonization factors that are likely to contribute to the pathogenic potential of this food-borne pathogen.
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Francetic O, Buddelmeijer N, Lewenza S, Kumamoto CA, Pugsley AP. Signal recognition particle-dependent inner membrane targeting of the PulG Pseudopilin component of a type II secretion system. J Bacteriol 2006; 189:1783-93. [PMID: 17158657 PMCID: PMC1855701 DOI: 10.1128/jb.01230-06] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pseudopilin PulG is an essential component of the pullulanase-specific type II secretion system from Klebsiella oxytoca. PulG is the major subunit of a short, thin-filament pseudopilus, which presumably elongates and retracts in the periplasm, acting as a dynamic piston to promote pullulanase secretion. It has a signal sequence-like N-terminal segment that, according to studies with green and red fluorescent protein chimeras, anchors unassembled PulG in the inner membrane. We analyzed the early steps of PulG inner membrane targeting and insertion in Escherichia coli derivatives defective in different protein targeting and export factors. The beta-galactosidase activity in strains producing a PulG-LacZ hybrid protein increased substantially when the dsbA, dsbB, or all sec genes tested except secB were compromised by mutations. To facilitate analysis of native PulG membrane insertion, a leader peptidase cleavage site was engineered downstream from the N-terminal transmembrane segment (PrePulG*). Unprocessed PrePulG* was detected in strains carrying mutations in secA, secY, secE, and secD genes, including some novel alleles of secY and secD. Furthermore, depletion of the Ffh component of the signal recognition particle (SRP) completely abolished PrePulG* processing, without affecting the Sec-dependent export of periplasmic MalE and RbsB proteins. Thus, PulG is cotranslationally targeted to the inner membrane Sec translocase by SRP.
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Affiliation(s)
- Olivera Francetic
- Molecular Genetics Unit, Institut Pasteur, 25 Rue du Dr. Roux, 75724 Paris Cedex 15, France
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Abstract
The Klebsiella oxytoca pullulanase secreton (type II secretion system) components PulM and PulL were tagged at their N termini with green fluorescent protein (GFP), and their subcellular location was examined by fluorescence microscopy and fractionation. When produced at moderate levels without other secreton components in Escherichia coli, both chimeras were envelope associated, as are the native proteins. Fluorescent GFP-PulM was evenly distributed over the cell envelope, with occasional brighter foci. Under the same conditions, GFP-PulL was barely detectable in the envelope by fluorescence microscopy. When produced together with all other secreton components, GFP-PulL exhibited circumferential fluorescence, with numerous brighter patches. The envelope-associated fluorescence of GFP-PulL was almost completely abolished when native PulL was also produced, suggesting that the chimera cannot compete with PulL for association with other secreton components. The patches of GFP-PulL might represent functional secretons, since GFP-PulM also appeared in similar patches. GFP-PulM and GFP-PulL both appeared in spherical polar foci when made at high levels. In K. oxytoca, GFP-PulM was evenly distributed over the cell envelope, with few patches, whereas GFP-PulL showed only weak envelope-associated fluorescence. These data suggest that, in contrast to their Vibrio cholerae Eps secreton counterparts (M. Scott, Z. Dossani, and M. Sandkvist, Proc. Natl. Acad. Sci. USA 98:13978-13983, 2001), PulM and PulL do not localize specifically to the cell poles and that the Pul secreton is distributed over the cell surface.
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Affiliation(s)
- Nienke Buddelmeijer
- Molecular Genetics Unit, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
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Abstract
Protein secretion systems in prokaryotes are increasingly shifting from being considered as experimental models for 'more complex' processes (i.e. eukaryotes) to being a major source of key biological questions in their own right. The pathways by which proteins move between compartments or insert into membranes in prokaryotic cells are certainly less numerous than in eukaryotes (though not dramatically so). However, the quality and complexity of bacterial protein targeting systems indicate that virtually all mechanistic problems associated with protein traffic were solved very efficiently well before eukaryotes appeared on the Earth crust. Indeed, recent studies have both increased the number of known prokaryotic protein traffic systems and indicated new layers of complexity for those that were already well characterized. This report describes some recent developments in bacterial protein traffic that were presented at two meetings in the autumn of 2003.
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Affiliation(s)
- Anthony P Pugsley
- Molecular Genetics Unit, CNRS URA2175, Institut Pasteur, 25, rue du Dr Roux, 75724, Paris 15, France.
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Abstract
Escherichia coli K-12, the most widely used laboratory bacterium, does not secrete proteins into the extracellular medium under standard growth conditions, despite possessing chromosomal genes encoding a putative type II secretion machinery (secreton). We show that in wild-type E.coli K-12, divergent transcription of the two operons in the main chromosomal gsp locus, encoding the majority of the secreton components, is silenced by the nucleoid-structuring protein H-NS. In mutants lacking H-NS, the secreton genes cloned on a moderate-copy-number plasmid are expressed and promote efficient secretion of the endogenous, co-regulated endochitinase ChiA. This is the first time that secretion of an endogenous extracellular protein has been demonstrated in E.coli K-12.
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Affiliation(s)
- O Francetic
- Unité de Génétique moléculaire and Unité de Physicochimie de Macromolécules biologiques, Centre National de la Recherche scientifique URA1773, Institut Pasteur, 25 rue du Dr Roux, 75734 Paris, Cedex 15, France
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Francetic O, Badaut C, Rimsky S, Pugsley AP. The ChiA (YheB) protein of Escherichia coli K-12 is an endochitinase whose gene is negatively controlled by the nucleoid-structuring protein H-NS. Mol Microbiol 2000; 35:1506-17. [PMID: 10760150 DOI: 10.1046/j.1365-2958.2000.01817.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The chromosome of Escherichia coli K-12 contains a putative gene, yheB (chiA), at centisome 74.7, whose product shows sequence similarity with chitinases of bacterial and viral origin. We cloned the chiA (yheB) gene and demonstrated that it codes for a 94.5 kDa periplasmic protein with endochitinase/lysozyme activity. Under standard laboratory growth conditions, chiA expression is very low, as shown by the Lac- phenotype of a chiA transcriptional fusion to a promoterless lacZ reporter. To identify factors that control chitinase gene expression, we generated random Tn10 insertions in the chromosome of the fusion-containing strain, selecting for a Lac+ phenotype. The majority of the mutations that caused a Lac+ phenotype mapped to the hns gene, encoding the nucleoid-structuring protein H-NS. Transcription of chiA in vivo is driven by a single sigma70 promoter and is derepressed in an hns mutant. Using a competitive gel retardation assay, we demonstrated that H-NS binds directly and with high affinity to the chiA promoter region. In addition to hns, other E. coli mutations causing defects in global regulatory proteins, such as fis, crp or stpA in combination with hns, increased chiA expression to different extents, as did decreasing the growth temperature from 37 degrees C to 30 degrees C. A possible physiological function of ChiA (YheB) endochitinase in E. coli K-12 is discussed.
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Affiliation(s)
- O Francetic
- Unité de Génétique moléculaire, CNRS URA1773, Institut Pasteur, 25 rue du Dr Roux, 75734 Paris, Cedex 15, France
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Abstract
Escherichia coli K-12 possesses a large number of chromosomal genes that, in other Gram-negative bacteria, are involved either in exoprotein secretion or in the formation of type IV pili. Some of these E. coli genes have been shown to encode proteins when expressed from heterologous promoters. Furthermore, at least two of these proteins are functional in heterologous complementation tests, but none of the genes examined so far is expressed when E. coli is grown under standard laboratory conditions. We propose that transcription of these genes is turned off during growth in laboratory medium, that their expression is controlled by environmental sensor proteins and that they could play an important role in pathogenicity or in the utilization of large polymers.
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Affiliation(s)
- A P Pugsley
- Unité de Génétique Moléculaire, CNRS URA 1773, Institut Pasteur, Paris, France.
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Pugsley AP, Francetic O, Possot OM, Sauvonnet N, Hardie KR. Recent progress and future directions in studies of the main terminal branch of the general secretory pathway in Gram-negative bacteria--a review. Gene 1997; 192:13-9. [PMID: 9224869 DOI: 10.1016/s0378-1119(96)00803-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The main terminal branch (MTB) of the general secretory pathway is used by a wide variety of Gram- bacteria to transport exoproteins from the periplasm to the outside milieu. Recent work has led to the identification of the function of two of its 14 (or more) components: an enzyme with type-IV prepilin peptidase activity and a chaperone-like protein required for the insertion of another of the MTB components into the outer membrane. Despite these important discoveries, little tangible progress has been made towards identifying MTB components that determine secretion specificity (presumably by binding to cognate exoproteins) or which form the putative channel through which exoproteins are transported across the outer membrane. However, the idea that the single integral outer membrane component of the MTB could line the wall of this channel, and the intriguing possibility that other components of the MTB form a rudimentary type-IV pilus-like structure that might span the periplasm both deserve more careful examination. Although Escherichia coli K-12 does not normally secrete exoproteins, its chromosome contains an apparently complete set of genes coding for MTB components. At least two of these genes code for functional proteins, but the operon in which twelve of the genes are located does not appear to be expressed. We are currently searching for conditions which allow these genes to be expressed with the eventual aim of identifying the protein(s) that E. coli K-12 can secrete.
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Affiliation(s)
- A P Pugsley
- Unité de Génétique Moléculaire, CNRS URA 1149, Institut Pasteur, Paris, France.
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Pugsley AP, Francetic O, Hardie K, Possot OM, Sauvonnet N, Seydel A. Pullulanase: model protein substrate for the general secretory pathway of gram-negative bacteria. Folia Microbiol (Praha) 1997; 42:184-92. [PMID: 9246760 DOI: 10.1007/bf02818976] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pullulanase of Klebsiella oxytoca is one of a wide variety of extracellular proteins that are secreted by Gram-negative bacteria by the complex main terminal branch (MTB) of the general secretory pathway. The roles of some of the 14 components of the MTB are now becoming clear. In this review it is proposed that most of these proteins form a complex, the secretion, that spans the cell envelope to control the opening and closing of channel in the outer membrane. Progress toward the goal of testing this model is reviewed.
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Affiliation(s)
- A P Pugsley
- Unité de Génétique Moléculaire, CNRS URA 1149, Institut Pasteur, Paris, France
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Francetic O, Kumamoto CA. Escherichia coli SecB stimulates export without maintaining export competence of ribose-binding protein signal sequence mutants. J Bacteriol 1996; 178:5954-9. [PMID: 8830692 PMCID: PMC178452 DOI: 10.1128/jb.178.20.5954-5959.1996] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Ribose-binding protein (RBP) is exported to the periplasm of Escherichia coli via the general export pathway. An rbsB-lacZ gene fusion was constructed and used to select mutants defective in RBP export. The spontaneous Lac+ mutants isolated in this selection contained either single-amino-acid substitutions or a deletion of the RBP signal sequence. Intact rbsB genes containing eight different point mutations in the signal sequence were reconstructed, and the effects of the mutations on RBP export were examined. Most of the mutations caused severe defects in RBP export. In addition, different suppressor mutations in SecY/PrlA protein were analyzed for their effects on the export of RBP signal sequence mutants in the presence or absence of SecB. Several RBP signal sequence mutants were efficiently suppressed, but others were not suppressed. Export of an RBP signal sequence mutant in prlA mutant strains was partially dependent on SecB, which is in contrast to the SecB independence of wild-type RBP export. However, the kinetics of export of an RBP signal sequence mutant point to a rapid loss of pre-RBP export competence, which occurs in strains containing or lacking SecB. These results suggest that SecB does not stabilize the export-competent conformation of RBP and may affect translocation by stabilizing the binding of pre-RBP at the translocation site.
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Affiliation(s)
- O Francetic
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Abstract
Systematic sequencing of the Escherichia coli K-12 chromosome (GenBank entry U18997) has revealed the presence of an apparently complete operon of genes (the gspC-0 operon) similar to genes coding for components of the main terminal branch of the general secretory pathway (e.g., the Klebsiella oxytoca pulC-0 pullulanase secretion operon) and to related genes required for type IV pilus biogenesis. For example, the last gene in the gsp operon, gspO (formerly hopD), encodes a protein which is similar to several type IV prepilin peptidases. Expression of gspO from lacZp promotes cleavage of two known prepilin peptidase substrates in E. coli K-12: Neisseria gonorrhoeae type IV prepilin and K. oxytoca prePulG protein. gspO also complements a mutation in the corresponding gene (pulO) of the pullulanase secretion operon when it is expressed from lacZp. Another gene in the gsp operon, gspG (formerly hopG), encodes a protein similar to prePulG, a component of the pullulanase secretion pathway. Expression of gspG from lacZp leads to production of a protein which (i) is recognized by PulG-specific antiserum (and by antiserum against the Pseudomonas aeruginosa PulG homolog XcpG [formerly XcpT]), (ii) is processed in cells expressing gspO, and (iii) restores secretion in cells carrying a pulG mutation. The chromosomal copies of gspG and gspO are apparently not expressed, probably because of very weak transcription from the upstream region, as measured by using a chromosomal gspC-lacZ operon fusion. Thus, the gsp operon of E. coli K-12 includes at least two functional genes which, together with the rest of the operon, are probably not expressed under laboratory conditions.
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Affiliation(s)
- O Francetic
- Unité de Génétique Moléculaire, Centre National de la Recherche Scientifique Unité de Recherche Associée 1149, Institut Pasteur, Paris, France
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