1
|
He LH, Wang H, Liu Y, Kang M, Li T, Li CC, Tong AP, Zhu YB, Song YJ, Savarino SJ, Prouty MG, Xia D, Bao R. Chaperone-tip adhesin complex is vital for synergistic activation of CFA/I fimbriae biogenesis. PLoS Pathog 2020; 16:e1008848. [PMID: 33007034 PMCID: PMC7531860 DOI: 10.1371/journal.ppat.1008848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 07/30/2020] [Indexed: 02/05/2023] Open
Abstract
Colonization factor CFA/I defines the major adhesive fimbriae of enterotoxigenic Escherichia coli and mediates bacterial attachment to host intestinal epithelial cells. The CFA/I fimbria consists of a tip-localized minor adhesive subunit, CfaE, and thousands of copies of the major subunit CfaB polymerized into an ordered helical rod. Biosynthesis of CFA/I fimbriae requires the assistance of the periplasmic chaperone CfaA and outer membrane usher CfaC. Although the CfaE subunit is proposed to initiate the assembly of CFA/I fimbriae, how it performs this function remains elusive. Here, we report the establishment of an in vitro assay for CFA/I fimbria assembly and show that stabilized CfaA-CfaB and CfaA-CfaE binary complexes together with CfaC are sufficient to drive fimbria formation. The presence of both CfaA-CfaE and CfaC accelerates fimbria formation, while the absence of either component leads to linearized CfaB polymers in vitro. We further report the crystal structure of the stabilized CfaA-CfaE complex, revealing features unique for biogenesis of Class 5 fimbriae.
Collapse
Affiliation(s)
- Li-hui He
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Hao Wang
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States of America
- Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Yang Liu
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States of America
- Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Mei Kang
- Department of Laboratory medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Tao Li
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Chang-cheng Li
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Ai-ping Tong
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Yi-bo Zhu
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Ying-jie Song
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Stephen J. Savarino
- Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
- Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD, United States of America
| | - Michael G. Prouty
- Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Rui Bao
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| |
Collapse
|
2
|
Liu Y, Sun C, Han L, Yu Y, Zhou H, Shao Q, Lou J, Zhao Y, Huang Y. Conformational Dynamics, Intramolecular Domain Conformation Signaling, and Activation of Apo-FimD Revealed by Single-Molecule Fluorescence Resonance Energy Transfer Studies. Biochemistry 2019; 58:1931-1941. [PMID: 30888187 DOI: 10.1021/acs.biochem.9b00080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chaperone-usher secretion pathway is a conserved bacterial protein secretion system dedicated to the biogenesis of adhesive fibers. Usher, a multidomain-containing outer membrane protein, plays a central role in this process by acting as a molecular machine that recruits different chaperone-subunit complexes, catalyzes subunit polymerization, and forms a channel for secretion of the assembled subunits. While recent crystal structural studies have greatly advanced our understanding of the structure and function of ushers, the overall architecture of the full-length apo-usher, the molecular events that dictate conformational changes in usher during pilus biogenesis, and its activation by the specific chaperone-adhesin complex remain largely elusive. Using single-molecule fluorescence resonance energy transfer studies, we found that the substrate-free usher FimD (apo-FimD) adopts a contracted conformation that is distinct from its substrate-bound states; both the N-terminal domain (NTD) and the C-terminal domain (CTD) of apo-FimD are highly dynamic, and FimD coordinates its domain conformational changes via intramolecular domain conformation signaling. By combining these studies with in vitro photo-cross-linking studies, we further show that only the chaperone-bound adhesin (FimC:FimH) can be transferred to the CTD, dislocates the plug domain, and triggers conformational changes in the remaining FimD domains. Taken together, these studies delineate an overall architecture of the full-length apo-FimD, provide detailed mechanic insight into the activation of apo-FimD, and explain why FimD could adjust its conformational states to perform multiple functions in each cycle of pilus subunit addition and ensure that pilus assembly proceeds progressively in a cellular energy-free environment.
Collapse
Affiliation(s)
- Yanqing Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Chuanqi Sun
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Long Han
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Yuqi Yu
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
| | - Haizhen Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China
| | - Qiang Shao
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
| | - Jizhong Lou
- University of Chinese Academy of Sciences , Beijing 100101 , China.,Key Laboratory of RNA Biology, Institute of Biophysics , Chinese Academy of Sciences , Beijing 100101 , China
| | - Yongfang Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Yihua Huang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| |
Collapse
|
3
|
Omattage NS, Deng Z, Pinkner JS, Dodson KW, Almqvist F, Yuan P, Hultgren SJ. Structural basis for usher activation and intramolecular subunit transfer in P pilus biogenesis in Escherichia coli. Nat Microbiol 2018; 3:1362-1368. [PMID: 30275511 PMCID: PMC6258349 DOI: 10.1038/s41564-018-0255-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 08/24/2018] [Indexed: 11/16/2022]
Abstract
Chaperone-usher pathway pili are extracellular proteinaceous fibres ubiquitously found on Gram-negative bacteria, and mediate host-pathogen interactions and biofilm formation critical in pathogenesis in numerous human diseases1. During pilus assembly, an outer membrane macromolecular machine called the usher catalyses pilus biogenesis from the individual subunits that are delivered as chaperone-subunit complexes in the periplasm. The usher orchestrates pilus assembly using all five functional domains: a 24-stranded transmembrane β-barrel translocation domain, a β-sandwich plug domain, an amino-terminal periplasmic domain and two carboxy-terminal periplasmic domains (CTD1 and CTD2)2-6. Despite extensive structural and functional characterization, the mechanism by which the usher is activated to initiate pilus biogenesis is unknown. Here, we present the crystal structure of the full-length PapC usher from Escherichia coli in complex with its cognate PapDG chaperone-subunit complex in a pre-activation state, elucidating molecular details of how the usher is specifically engaged by allosteric interactions with its substrate preceding activation and how the usher facilitates the transfer of subunits from the amino-terminal periplasmic domain to the CTDs during pilus assembly. This work elucidates the intricate workings of a molecular machine that catalyses chaperone-usher pathway pilus assembly and opens the door for the development of potent inhibitors to block pilus biogenesis.
Collapse
Affiliation(s)
- Natalie S Omattage
- Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA
- Center for Women's Infectious Disease Research, Washington University in St Louis, St Louis, MO, USA
| | - Zengqin Deng
- Department of Cell Biology and Physiology, Washington University in St Louis, St Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Jerome S Pinkner
- Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA
- Center for Women's Infectious Disease Research, Washington University in St Louis, St Louis, MO, USA
| | - Karen W Dodson
- Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA
- Center for Women's Infectious Disease Research, Washington University in St Louis, St Louis, MO, USA
| | - Fredrik Almqvist
- Department of Chemistry, Umeå University, Umeå, Sweden
- Umeå Center for Microbial Research, Umeå University, Umeå, Sweden
| | - Peng Yuan
- Department of Cell Biology and Physiology, Washington University in St Louis, St Louis, MO, USA.
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA.
| | - Scott J Hultgren
- Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA.
- Center for Women's Infectious Disease Research, Washington University in St Louis, St Louis, MO, USA.
| |
Collapse
|
4
|
Innovative Solutions to Sticky Situations: Antiadhesive Strategies for Treating Bacterial Infections. Microbiol Spectr 2017; 4. [PMID: 27227305 DOI: 10.1128/microbiolspec.vmbf-0023-2015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial adherence to host tissue is an essential process in pathogenesis, necessary for invasion and colonization and often required for the efficient delivery of toxins and other bacterial effectors. As existing treatment options for common bacterial infections dwindle, we find ourselves rapidly approaching a tipping point in our confrontation with antibiotic-resistant strains and in desperate need of new treatment options. Bacterial strains defective in adherence are typically avirulent and unable to cause infection in animal models. The importance of this initial binding event in the pathogenic cascade highlights its potential as a novel therapeutic target. This article seeks to highlight a variety of strategies being employed to treat and prevent infection by targeting the mechanisms of bacterial adhesion. Advancements in this area include the development of novel antivirulence therapies using small molecules, vaccines, and peptides to target a variety of bacterial infections. These therapies target bacterial adhesion through a number of mechanisms, including inhibition of pathogen receptor biogenesis, competition-based strategies with receptor and adhesin analogs, and the inhibition of binding through neutralizing antibodies. While this article is not an exhaustive description of every advancement in the field, we hope it will highlight several promising examples of the therapeutic potential of antiadhesive strategies.
Collapse
|
5
|
Pham T, Henderson NS, Werneburg GT, Thanassi DG, Delcour AH. Electrostatic networks control plug stabilization in the PapC usher. Mol Membr Biol 2016; 32:198-207. [PMID: 27181766 DOI: 10.3109/09687688.2016.1160450] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The PapC usher, a β-barrel pore in the outer membrane of uropathogenic Escherichia coli, is used for assembly of the P pilus, a key virulence factor in bacterial colonization of human kidney cells. Each PapC protein is composed of a 24-stranded β-barrel channel, flanked by N- and C-terminal globular domains protruding into the periplasm, and occluded by a plug domain (PD). The PD is displaced from the channel towards the periplasm during pilus biogenesis, but the molecular mechanism for PD displacement remains unclear. Two structural features within the β-barrel, an α-helix and β5-6 hairpin loop, may play roles in controlling plug stabilization. Here we have tested clusters of residues at the interface of the plug, barrel, α-helix and hairpin, which participate in electrostatic networks. To assess the roles of these residues in plug stabilization, we used patch-clamp electrophysiology to compare the activity of wild-type and mutant PapC channels containing alanine substitutions at these sites. Mutations interrupting each of two salt bridge networks were relatively ineffective in disrupting plug stabilization. However, mutation of two pairs of arginines located at the inner and the outer surfaces of the PD resulted in an enhanced propensity for plug displacement. One arginine pair involved in a repulsive interaction between the linkers that tether the plug to the β-barrel was particularly sensitive to mutation. These results suggest that plug displacement, which is necessary for pilus assembly and translocation, may require a weakening of key electrostatic interactions between the plug linkers, and the plug and the α-helix.
Collapse
Affiliation(s)
- Thieng Pham
- a Department of Biology and Biochemistry , University of Houston , Houston , TX and
| | - Nadine S Henderson
- b Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook , NY , USA
| | - Glenn T Werneburg
- b Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook , NY , USA
| | - David G Thanassi
- b Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook , NY , USA
| | - Anne H Delcour
- a Department of Biology and Biochemistry , University of Houston , Houston , TX and
| |
Collapse
|
6
|
Chahales P, Thanassi DG. Structure, Function, and Assembly of Adhesive Organelles by Uropathogenic Bacteria. Microbiol Spectr 2015; 3:10.1128/microbiolspec.UTI-0018-2013. [PMID: 26542038 PMCID: PMC4638162 DOI: 10.1128/microbiolspec.uti-0018-2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 01/02/2023] Open
Abstract
Bacteria assemble a wide range of adhesive proteins, termed adhesins, to mediate binding to receptors and colonization of surfaces. For pathogenic bacteria, adhesins are critical for early stages of infection, allowing the bacteria to initiate contact with host cells, colonize different tissues, and establish a foothold within the host. The adhesins expressed by a pathogen are also critical for bacterial-bacterial interactions and the formation of bacterial communities, including biofilms. The ability to adhere to host tissues is particularly important for bacteria that colonize sites such as the urinary tract, where the flow of urine functions to maintain sterility by washing away non-adherent pathogens. Adhesins vary from monomeric proteins that are directly anchored to the bacterial surface to polymeric, hair-like fibers that extend out from the cell surface. These latter fibers are termed pili or fimbriae, and were among the first identified virulence factors of uropathogenic Escherichia coli. Studies since then have identified a range of both pilus and non-pilus adhesins that contribute to bacterial colonization of the urinary tract, and have revealed molecular details of the structures, assembly pathways, and functions of these adhesive organelles. In this review, we describe the different types of adhesins expressed by both Gram-negative and Gram-positive uropathogens, what is known about their structures, how they are assembled on the bacterial surface, and the functions of specific adhesins in the pathogenesis of urinary tract infections.
Collapse
Affiliation(s)
- Peter Chahales
- Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794
| | - David G Thanassi
- Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794
| |
Collapse
|
7
|
Lillington J, Geibel S, Waksman G. Reprint of "Biogenesis and adhesion of type 1 and P pili". Biochim Biophys Acta Gen Subj 2014; 1850:554-64. [PMID: 25063559 DOI: 10.1016/j.bbagen.2014.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND Uropathogenic Escherichia coli (UPEC) cause urinary tract infections (UTIs) in approximately 50% of women. These bacteria use type 1 and P pili for host recognition and attachment. These pili are assembled by the chaperone-usher pathway of pilus biogenesis. SCOPE OF REVIEW The review examines the biogenesis and adhesion of the UPEC type 1 and P pili. Particular emphasis is drawn to the role of the outer membrane usher protein. The structural properties of the complete pilus are also examined to highlight the strength and functionality of the final assembly. MAJOR CONCLUSIONS The usher orchestrates the sequential addition of pilus subunits in a defined order. This process follows a subunit-incorporation cycle which consists of four steps: recruitment at the usher N-terminal domain, donor-strand exchange with the previously assembled subunit, transfer to the usher C-terminal domains and translocation of the nascent pilus. Adhesion by the type 1 and P pili is strengthened by the quaternary structure of their rod sections. The rod is endowed with spring-like properties which provide mechanical resistance against urine flow. The distal adhesins operate differently from one another, targeting receptors in a specific manner. The biogenesis and adhesion of type 1 and P pili are being therapeutically targeted, and efforts to prevent pilus growth or adherence are described. GENERAL SIGNIFICANCE The combination of structural and biochemical study has led to the detailed mechanistic understanding of this membrane spanning nano-machine. This can now be exploited to design novel drugs able to inhibit virulence. This is vital in the present era of resurgent antibiotic resistance. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
Collapse
Affiliation(s)
- James Lillington
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Sebastian Geibel
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
| |
Collapse
|
8
|
Lillington J, Geibel S, Waksman G. Biogenesis and adhesion of type 1 and P pili. Biochim Biophys Acta Gen Subj 2014; 1840:2783-93. [PMID: 24797039 DOI: 10.1016/j.bbagen.2014.04.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 01/22/2023]
Abstract
BACKGROUND Uropathogenic Escherichia coli (UPEC) cause urinary tract infections (UTIs) in approximately 50% of women. These bacteria use type 1 and P pili for host recognition and attachment. These pili are assembled by the chaperone-usher pathway of pilus biogenesis. SCOPE OF REVIEW The review examines the biogenesis and adhesion of the UPEC type 1 and P pili. Particular emphasis is drawn to the role of the outer membrane usher protein. The structural properties of the complete pilus are also examined to highlight the strength and functionality of the final assembly. MAJOR CONCLUSIONS The usher orchestrates the sequential addition of pilus subunits in a defined order. This process follows a subunit-incorporation cycle which consists of four steps: recruitment at the usher N-terminal domain, donor-strand exchange with the previously assembled subunit, transfer to the usher C-terminal domains and translocation of the nascent pilus. Adhesion by the type 1 and P pili is strengthened by the quaternary structure of their rod sections. The rod is endowed with spring-like properties which provide mechanical resistance against urine flow. The distal adhesins operate differently from one another, targeting receptors in a specific manner. The biogenesis and adhesion of type 1 and P pili are being therapeutically targeted, and efforts to prevent pilus growth or adherence are described. GENERAL SIGNIFICANCE The combination of structural and biochemical study has led to the detailed mechanistic understanding of this membrane spanning nano-machine. This can now be exploited to design novel drugs able to inhibit virulence. This is vital in the present era of resurgent antibiotic resistance. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
Collapse
Affiliation(s)
- James Lillington
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Sebastian Geibel
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
| |
Collapse
|
9
|
Bodelón G, Palomino C, Fernández LÁ. Immunoglobulin domains inEscherichia coliand other enterobacteria: from pathogenesis to applications in antibody technologies. FEMS Microbiol Rev 2013; 37:204-50. [DOI: 10.1111/j.1574-6976.2012.00347.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 06/07/2012] [Accepted: 06/14/2012] [Indexed: 11/28/2022] Open
|
10
|
Allen WJ, Phan G, Hultgren SJ, Waksman G. Dissection of pilus tip assembly by the FimD usher monomer. J Mol Biol 2013; 425:958-67. [PMID: 23295826 PMCID: PMC3650583 DOI: 10.1016/j.jmb.2012.12.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 12/21/2012] [Accepted: 12/22/2012] [Indexed: 01/08/2023]
Abstract
Type 1 pili are representative of a class of bacterial surface structures assembled by the conserved chaperone/usher pathway and used by uropathogenic Escherichia coli to attach to bladder cells during infection. The outer membrane assembly platform-the usher-is critical for the formation of pili, catalysing the polymerisation of pilus subunits and enabling the secretion of the nascent pilus. Despite extensive structural characterisation of the usher, a number of questions about its mechanism remain, notably its oligomerisation state, and how it orchestrates the ordered assembly of pilus subunits. We demonstrate here that the FimD usher is able to catalyse in vitro pilus assembly effectively in its monomeric form. Furthermore, by establishing the kinetics of usher-catalysed reactions between various pilus subunits, we establish a complete kinetic model of tip fibrillum assembly, able to account for the order of subunits in native type 1 pili.
Collapse
Affiliation(s)
- William J. Allen
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Gilles Phan
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Scott J. Hultgren
- Center for Women's Infectious Disease Research, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8230, St. Louis, MO 63110, USA
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
- Corresponding author.
| |
Collapse
|
11
|
Morrissey B, Leney AC, Toste Rêgo A, Phan G, Allen WJ, Verger D, Waksman G, Ashcroft AE, Radford SE. The role of chaperone-subunit usher domain interactions in the mechanism of bacterial pilus biogenesis revealed by ESI-MS. Mol Cell Proteomics 2012; 11:M111.015289. [PMID: 22371487 PMCID: PMC3394950 DOI: 10.1074/mcp.m111.015289] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/23/2012] [Indexed: 01/12/2023] Open
Abstract
The PapC usher is a β-barrel outer membrane protein essential for assembly and secretion of P pili that are required for adhesion of pathogenic E. coli, which cause the development of pyelonephritis. Multiple protein subunits form the P pilus, the highly specific assembly of which is coordinated by the usher. Despite a wealth of structural knowledge, how the usher catalyzes subunit polymerization and orchestrates a correct and functional order of subunit assembly remain unclear. Here, the ability of the soluble N-terminal (UsherN), C-terminal (UsherC2), and Plug (UsherP) domains of the usher to bind different chaperone-subunit (PapDPapX) complexes is investigated using noncovalent electrospray ionization mass spectrometry. The results reveal that each usher domain is able to bind all six PapDPapX complexes, consistent with an active role of all three usher domains in pilus biogenesis. Using collision induced dissociation, combined with competition binding experiments and dissection of the adhesin subunit, PapG, into separate pilin and adhesin domains, the results reveal why PapG has a uniquely high affinity for the usher, which is consistent with this subunit always being displayed at the pilus tip. In addition, we show how the different soluble usher domains cooperate to coordinate and control efficient pilus assembly at the usher platform. As well as providing new information about the protein-protein interactions that determine pilus biogenesis, the results highlight the power of noncovalent MS to interrogate biological mechanisms, especially in complex mixtures of species.
Collapse
MESH Headings
- Adhesins, Escherichia coli/chemistry
- Adhesins, Escherichia coli/genetics
- Adhesins, Escherichia coli/metabolism
- Bacterial Adhesion
- Binding Sites
- Binding, Competitive
- Escherichia coli/pathogenicity
- Escherichia coli/physiology
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Fimbriae Proteins/chemistry
- Fimbriae Proteins/genetics
- Fimbriae Proteins/metabolism
- Fimbriae, Bacterial/chemistry
- Fimbriae, Bacterial/genetics
- Fimbriae, Bacterial/metabolism
- Models, Molecular
- Molecular Chaperones/chemistry
- Molecular Chaperones/genetics
- Molecular Chaperones/metabolism
- Periplasmic Proteins/chemistry
- Periplasmic Proteins/genetics
- Periplasmic Proteins/metabolism
- Porins/chemistry
- Porins/genetics
- Porins/metabolism
- Protein Binding
- Protein Structure, Tertiary
- Protein Subunits/chemistry
- Protein Subunits/genetics
- Protein Subunits/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Spectrometry, Mass, Electrospray Ionization
Collapse
Affiliation(s)
- Bethny Morrissey
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| | - Aneika C. Leney
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| | - Ana Toste Rêgo
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Gilles Phan
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - William J. Allen
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Denis Verger
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Gabriel Waksman
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Alison E. Ashcroft
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| | - Sheena E. Radford
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| |
Collapse
|
12
|
Domain activities of PapC usher reveal the mechanism of action of an Escherichia coli molecular machine. Proc Natl Acad Sci U S A 2012; 109:9563-8. [PMID: 22645361 DOI: 10.1073/pnas.1207085109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
P pili are prototypical chaperone-usher pathway-assembled pili used by Gram-negative bacteria to adhere to host tissues. The PapC usher contains five functional domains: a transmembrane β-barrel, a β-sandwich Plug, an N-terminal (periplasmic) domain (NTD), and two C-terminal (periplasmic) domains, CTD1 and CTD2. Here, we delineated usher domain interactions between themselves and with chaperone-subunit complexes and showed that overexpression of individual usher domains inhibits pilus assembly. Prior work revealed that the Plug domain occludes the pore of the transmembrane domain of a solitary usher, but the chaperone-adhesin-bound usher has its Plug displaced from the pore, adjacent to the NTD. We demonstrate an interaction between the NTD and Plug domains that suggests a biophysical basis for usher gating. Furthermore, we found that the NTD exhibits high-affinity binding to the chaperone-adhesin (PapDG) complex and low-affinity binding to the major tip subunit PapE (PapDE). We also demonstrate that CTD2 binds with lower affinity to all tested chaperone-subunit complexes except for the chaperone-terminator subunit (PapDH) and has a catalytic role in dissociating the NTD-PapDG complex, suggesting an interplay between recruitment to the NTD and transfer to CTD2 during pilus initiation. The Plug domain and the NTD-Plug complex bound all of the chaperone-subunit complexes tested including PapDH, suggesting that the Plug actively recruits chaperone-subunit complexes to the usher and is the sole recruiter of PapDH. Overall, our studies reveal the cooperative, active roles played by periplasmic domains of the usher to initiate, grow, and terminate a prototypical chaperone-usher pathway pilus.
Collapse
|
13
|
Allen WJ, Phan G, Waksman G. Pilus biogenesis at the outer membrane of Gram-negative bacterial pathogens. Curr Opin Struct Biol 2012; 22:500-6. [PMID: 22402496 DOI: 10.1016/j.sbi.2012.02.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 02/16/2012] [Accepted: 02/17/2012] [Indexed: 11/24/2022]
Abstract
Pili belong to a broad class of bacterial surface structures that play a key role in infection and pathogenicity. The largest and best characterised pilus biogenesis system--the chaperone-usher pathway--is particularly remarkable in its ability to synthesise and display highly organised structures at the outer membrane without any input from endogenous energy sources. The past few years have heralded exciting new developments in our understanding of the structural biology and mechanism of pilus assembly, which are discussed in this review. Such knowledge will be particularly important in the future, as we approach an era of widespread resistance to common antibiotics and require new targets.
Collapse
Affiliation(s)
- William J Allen
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, WC1E 7HX London, UK
| | | | | |
Collapse
|
14
|
Structural insights into the biogenesis and biofilm formation by the Escherichia coli common pilus. Proc Natl Acad Sci U S A 2012; 109:3950-5. [PMID: 22355107 DOI: 10.1073/pnas.1106733109] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacteria have evolved a variety of mechanisms for developing community-based biofilms. These bacterial aggregates are of clinical importance, as they are a major source of recurrent disease. Bacterial surface fibers (pili) permit adherence to biotic and abiotic substrates, often in a highly specific manner. The Escherichia coli common pilus (ECP) represents a remarkable family of extracellular fibers that are associated with both disease-causing and commensal strains. ECP plays a dual role in early-stage biofilm development and host cell recognition. Despite being the most common fimbrial structure, relatively little is known regarding its biogenesis, architecture, and function. Here we report atomic-resolution insight into the biogenesis and architecture of ECP. We also derive a structural model for entwined ECP fibers that not only illuminates interbacteria communication during biofilm formation but also provides a useful foundation for the design of novel nanofibers.
Collapse
|
15
|
The fimbrial usher FimD follows the SurA-BamB pathway for its assembly in the outer membrane of Escherichia coli. J Bacteriol 2011; 193:5222-30. [PMID: 21784935 DOI: 10.1128/jb.05585-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fimbrial ushers are the largest β-barrel outer membrane proteins (OMPs) known to date, which function in the polymerization of fimbriae and their translocation to the bacterial surface. Folding and assembly of these complex OMPs are not characterized. Here, we investigate the role of periplasmic chaperones (SurA, Skp, DegP, and FkpA) and individual components of the β-barrel assembly machinery (BAM) complex (BamA, BamB, BamC, and BamE) in the folding of the Escherichia coli FimD usher. The FimD level is dramatically reduced (∼30-fold) in a surA null mutant, but a strong cell envelope stress is constitutively activated with upregulation of DegP (∼10-fold). To demonstrate a direct role of SurA, FimD folding was analyzed in a conditional surA mutant in which SurA expression was controlled. In this strain, FimD is depleted from bacteria in parallel to SurA without significant upregulation of DegP. Interestingly, the dependency on SurA is higher for FimD than for other OMPs. We also demonstrate that a functional BAM complex is needed for folding of FimD. In addition, FimD levels were strongly reduced (∼5-fold) in a mutant lacking the accessory lipoprotein BamB. The critical role of BamB for FimD folding was confirmed by complementation and BamB depletion experiments. Similar to SurA dependency, FimD showed a stronger dependency on BamB than OMPs. On the other hand, folding of FimD was only marginally affected in bamC and bamE mutants. Collectively, our results indicate that FimD usher follows the SurA-BamB pathway for its assembly. The preferential use of this pathway for the folding of OMPs with large β-barrels is discussed.
Collapse
|
16
|
Phan G, Remaut H, Wang T, Allen WJ, Pirker KF, Lebedev A, Henderson NS, Geibel S, Volkan E, Yan J, Kunze MBA, Pinkner JS, Ford B, Kay CWM, Li H, Hultgren SJ, Thanassi DG, Waksman G. Crystal structure of the FimD usher bound to its cognate FimC-FimH substrate. Nature 2011; 474:49-53. [PMID: 21637253 PMCID: PMC3162478 DOI: 10.1038/nature10109] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 04/13/2011] [Indexed: 11/29/2022]
Abstract
Type 1 pili are the archetypal representative of a widespread class of adhesive multisubunit fibres in Gram-negative bacteria. During pilus assembly, subunits dock as chaperone-bound complexes to an usher, which catalyzes their polymerization and mediates pilus translocation across the outer membrane. We report the crystal structure of the full-length FimD usher bound to the FimC:FimH chaperone:adhesin complex and that of the unbound form of the FimD translocation domain. The FimD:FimC:FimH structure shows FimH inserted inside the FimD 24-stranded β-barrel translocation channel. FimC:FimH is held in place through interactions with the two C-terminal periplasmic domains of FimD, a binding mode confirmed in solution by electron paramagnetic resonance spectroscopy. To accommodate FimH, the usher plug domain is displaced from the barrel lumen to the periplasm, concomitant with a dramatic conformational change in the β-barrel. The N-terminal domain of FimD is observed in an ideal position to catalyse incorporation of a newly recruited chaperone:subunit complex. The FimD:FimC:FimH structure provides unique insights into the pilus subunit incorporation cycle, and captures the first view of a protein transporter in the act of secreting its cognate substrate.
Collapse
Affiliation(s)
- Gilles Phan
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Geibel S, Waksman G. Crystallography and Electron Microscopy of Chaperone/Usher Pilus Systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 715:159-74. [PMID: 21557063 DOI: 10.1007/978-94-007-0940-9_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- Sebastian Geibel
- Institute of Structural Molecular Biology, Birkbeck and University College London, London, UK.
| | | |
Collapse
|
18
|
Henderson NS, Ng TW, Talukder I, Thanassi DG. Function of the usher N-terminus in catalysing pilus assembly. Mol Microbiol 2010; 79:954-67. [PMID: 21299650 DOI: 10.1111/j.1365-2958.2010.07505.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The chaperone/usher (CU) pathway is a conserved bacterial secretion system that assembles adhesive fibres termed pili or fimbriae. Pilus biogenesis by the CU pathway requires a periplasmic chaperone and an outer membrane (OM) assembly platform termed the usher. The usher catalyses formation of subunit-subunit interactions to promote polymerization of the pilus fibre and provides the channel for fibre secretion. The mechanism by which the usher catalyses pilus assembly is not known. Using the P and type 1 pilus systems of uropathogenic Escherichia coli, we show that a conserved N-terminal disulphide region of the PapC and FimD ushers, as well as residue F4 of FimD, are required for the catalytic activity of the ushers. PapC disulphide loop mutants were able to bind PapDG chaperone-subunit complexes, but did not assemble PapG into pilus fibres. FimD disulphide loop and F4 mutants were able to bind chaperone-subunit complexes and initiate assembly of pilus fibres, but were defective for extending the pilus fibres, as measured using in vivo co-purification and in vitro pilus polymerization assays. These results suggest that the catalytic activity of PapC is required to initiate pilus biogenesis, whereas the catalytic activity of FimD is required for extension of the pilus fibre.
Collapse
Affiliation(s)
- Nadine S Henderson
- Center for Infectious Diseases, Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794-5120, USA
| | | | | | | |
Collapse
|
19
|
Outer membrane translocons: structural insights into channel formation. Trends Microbiol 2010; 19:40-8. [PMID: 21130656 DOI: 10.1016/j.tim.2010.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/18/2010] [Accepted: 10/29/2010] [Indexed: 01/26/2023]
Abstract
Gram-negative bacteria need to maintain the integrity of their outer membrane while also regulating the secretion of toxins and other macromolecules. A variety of dedicated outer membrane proteins (OMPs) facilitate this process. Recent structural work has shown that some of these proteins adopt classical β-barrel transmembrane structures and rely on structural changes within the barrel lumen to allow passage of substrate proteins. Other secretion systems have OMP components which use transmembrane α-helices and appear to function in a different way. Here we review a selection of recent structural studies which have major ramifications for our understanding of the passage of macromolecules across the outer membrane.
Collapse
|
20
|
Conserved Hydrophobic Clusters on the Surface of the Caf1A Usher C-Terminal Domain Are Important for F1 Antigen Assembly. J Mol Biol 2010; 403:243-59. [DOI: 10.1016/j.jmb.2010.08.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 08/13/2010] [Accepted: 08/17/2010] [Indexed: 11/24/2022]
|