1
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Geiger CJ, Wong GCL, O'Toole GA. A bacterial sense of touch: T4P retraction motor as a means of surface sensing by Pseudomonas aeruginosa PA14. J Bacteriol 2024:e0044223. [PMID: 38832786 DOI: 10.1128/jb.00442-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
Most microbial cells found in nature exist in matrix-covered, surface-attached communities known as biofilms. This mode of growth is initiated by the ability of the microbe to sense a surface on which to grow. The opportunistic pathogen Pseudomonas aeruginosa (Pa) PA14 utilizes a single polar flagellum and type 4 pili (T4P) to sense surfaces. For Pa, T4P-dependent "twitching" motility is characterized by effectively pulling the cell across a surface through a complex process of cooperative binding, pulling, and unbinding. T4P retraction is powered by hexameric ATPases. Pa cells that have engaged a surface increase production of the second messenger cyclic AMP (cAMP) over multiple generations via the Pil-Chp system. This rise in cAMP allows cells and their progeny to become better adapted for surface attachment and activates virulence pathways through the cAMP-binding transcription factor Vfr. While many studies have focused on mechanisms of T4P twitching and regulation of T4P production and function by the Pil-Chp system, the mechanism by which Pa senses and relays a surface-engagement signal to the cell is still an open question. Here we review the current state of the surface sensing literature for Pa, with a focus on T4P, and propose an integrated model of surface sensing whereby the retraction motor PilT senses and relays the signal to the Pil-Chp system via PilJ to drive cAMP production and adaptation to a surface lifestyle.
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Affiliation(s)
- C J Geiger
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - G C L Wong
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California, USA
| | - G A O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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2
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Zuke JD, Burton BM. From isotopically labeled DNA to fluorescently labeled dynamic pili: building a mechanistic model of DNA transport to the cytoplasmic membrane. Microbiol Mol Biol Rev 2024; 88:e0012523. [PMID: 38466096 PMCID: PMC10966944 DOI: 10.1128/mmbr.00125-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024] Open
Abstract
SUMMARYNatural competence, the physiological state wherein bacteria produce proteins that mediate extracellular DNA transport into the cytosol and the subsequent recombination of DNA into the genome, is conserved across the bacterial domain. DNA must successfully translocate across formidable permeability barriers during import, including the cell membrane(s) and the cell wall, that are normally impermeable to large DNA polymers. This review will examine the mechanisms underlying DNA transport from the extracellular space to the cytoplasmic membrane. First, the challenges inherent to DNA movement through the cell periphery will be discussed to provide context for DNA transport during natural competence. The following sections will trace the development of a comprehensive model for DNA translocation to the cytoplasmic membrane, highlighting the crucial studies performed over the last century that have contributed to building contemporary DNA import models. Finally, this review will conclude by reflecting on what is still unknown about the process and the possible solutions to overcome these limitations.
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Affiliation(s)
- Jason D. Zuke
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Briana M. Burton
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin, USA
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3
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Little JI, Singh PK, Zhao J, Dunn S, Matz H, Donnenberg MS. Type IV pili of Enterobacteriaceae species. EcoSal Plus 2024:eesp00032023. [PMID: 38294234 DOI: 10.1128/ecosalplus.esp-0003-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 12/01/2023] [Indexed: 02/01/2024]
Abstract
Type IV pili (T4Ps) are surface filaments widely distributed among bacteria and archaea. T4Ps are involved in many cellular functions and contribute to virulence in some species of bacteria. Due to the diversity of T4Ps, different properties have been observed for homologous proteins that make up T4Ps in various organisms. In this review, we highlight the essential components of T4Ps, their functions, and similarities to related systems. We emphasize the unique T4Ps of enteric pathogens within the Enterobacteriaceae family, which includes pathogenic strains of Escherichia coli and Salmonella. These include the bundle-forming pilus (BFP) of enteropathogenic E. coli (EPEC), longus (Lng) and colonization factor III (CFA/III) of enterotoxigenic E. coli (ETEC), T4P of Salmonella enterica serovar Typhi, Colonization Factor Citrobacter (CFC) of Citrobacter rodentium, T4P of Yersinia pseudotuberculosis, a ubiquitous T4P that was characterized in enterohemorrhagic E. coli (EHEC), and the R64 plasmid thin pilus. Finally, we highlight areas for further study.
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Affiliation(s)
- Janay I Little
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Pradip K Singh
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Jinlei Zhao
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Shakeera Dunn
- Internal Medicine Residency, Bayhealth Medical Center, Dover, Delaware, USA
| | - Hanover Matz
- Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
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4
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Sonani RR, Sanchez JC, Baumgardt JK, Kundra S, Wright ER, Craig L, Egelman EH. Tad and toxin-coregulated pilus structures reveal unexpected diversity in bacterial type IV pili. Proc Natl Acad Sci U S A 2023; 120:e2316668120. [PMID: 38011558 PMCID: PMC10710030 DOI: 10.1073/pnas.2316668120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 10/25/2023] [Indexed: 11/29/2023] Open
Abstract
Type IV pili (T4P) are ubiquitous in both bacteria and archaea. They are polymers of the major pilin protein, which has an extended and protruding N-terminal helix, α1, and a globular C-terminal domain. Cryo-EM structures have revealed key differences between the bacterial and archaeal T4P in their C-terminal domain structure and in the packing and continuity of α1. This segment forms a continuous α-helix in archaeal T4P but is partially melted in all published bacterial T4P structures due to a conserved helix breaking proline at position 22. The tad (tight adhesion) T4P are found in both bacteria and archaea and are thought to have been acquired by bacteria through horizontal transfer from archaea. Tad pilins are unique among the T4 pilins, being only 40 to 60 residues in length and entirely lacking a C-terminal domain. They also lack the Pro22 found in all high-resolution bacterial T4P structures. We show using cryo-EM that the bacterial tad pilus from Caulobacter crescentus is composed of continuous helical subunits that, like the archaeal pilins, lack the melted portion seen in other bacterial T4P and share the packing arrangement of the archaeal T4P. We further show that a bacterial T4P, the Vibrio cholerae toxin coregulated pilus, which lacks Pro22 but is not in the tad family, has a continuous N-terminal α-helix, yet its α1 s are arranged similar to those in other bacterial T4P. Our results highlight the role of Pro22 in helix melting and support an evolutionary relationship between tad and archaeal T4P.
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Affiliation(s)
- Ravi R. Sonani
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA22903
| | - Juan Carlos Sanchez
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Joseph K. Baumgardt
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Shivani Kundra
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Elizabeth R. Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Lisa Craig
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA22903
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5
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Nguyen M, Wu TH, Danielson K, Khan N, Zhang J, Craig L. Mechanism of secretion of TcpF by the Vibrio cholerae toxin-coregulated pilus. Proc Natl Acad Sci U S A 2023; 120:e2212664120. [PMID: 37040409 PMCID: PMC10120004 DOI: 10.1073/pnas.2212664120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 02/28/2023] [Indexed: 04/12/2023] Open
Abstract
Many bacteria possess dynamic filaments called Type IV pili (T4P) that perform diverse functions in colonization and dissemination, including host cell adhesion, DNA uptake, and secretion of protein substrates-exoproteins-from the periplasm to the extracellular space. The Vibrio cholerae toxin-coregulated pilus (TCP) and the enterotoxigenic Escherichia coli CFA/III pilus each mediates export of a single exoprotein, TcpF and CofJ, respectively. Here, we show that the disordered N-terminal segment of mature TcpF is the export signal (ES) recognized by TCP. Deletion of the ES disrupts secretion and causes TcpF to accumulate in the V. cholerae periplasm. The ES alone can mediate export of Neisseria gonorrhoeae FbpA by V. cholerae in a T4P-dependent manner. The ES is specific for its autologous T4P machinery as CofJ bearing the TcpF ES is exported by V. cholerae, whereas TcpF bearing the CofJ ES is not. Specificity is mediated by binding of the ES to TcpB, a minor pilin that primes pilus assembly and forms a trimer at the pilus tip. Finally, the ES is proteolyzed from the mature TcpF protein upon secretion. Together, these results provide a mechanism for delivery of TcpF across the outer membrane and release into the extracellular space.
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Affiliation(s)
- Minh Nguyen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Tzu-Hui Wu
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Katie J. Danielson
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Nabeel M. Khan
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - John Zhijia Zhang
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
| | - Lisa Craig
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BCV5A 1S6, Canada
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6
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Hughes HQ, Christman ND, Dalia TN, Ellison CK, Dalia AB. The PilT retraction ATPase promotes both extension and retraction of the MSHA type IVa pilus in Vibrio cholerae. PLoS Genet 2022; 18:e1010561. [PMID: 36542674 DOI: 10.1371/journal.pgen.1010561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 01/05/2023] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
Diverse bacterial species use type IVa pili (T4aP) to interact with their environments. The dynamic extension and retraction of T4aP is critical for their function, but the mechanisms that regulate this dynamic activity remain poorly understood. T4aP are typically extended via the activity of a dedicated extension motor ATPase and retracted via the action of an antagonistic retraction motor ATPase called PilT. These motors are generally functionally independent, and loss of PilT commonly results in T4aP hyperpiliation due to undeterred pilus extension. However, for the mannose-sensitive hemagglutinin (MSHA) T4aP of Vibrio cholerae, the loss of PilT unexpectedly results in a loss of surface piliation. Here, we employ a combination of genetic and cell biological approaches to dissect the underlying mechanism. Our results demonstrate that PilT is necessary for MSHA pilus extension in addition to its well-established role in promoting MSHA pilus retraction. Through a suppressor screen, we also provide genetic evidence that the MshA major pilin impacts pilus extension. Together, these findings contribute to our understanding of the factors that regulate pilus extension and describe a previously uncharacterized function for the PilT motor ATPase.
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Affiliation(s)
- Hannah Q Hughes
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Nicholas D Christman
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Triana N Dalia
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Courtney K Ellison
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Ankur B Dalia
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
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7
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Oki H, Kawahara K, Iimori M, Imoto Y, Nishiumi H, Maruno T, Uchiyama S, Muroga Y, Yoshida A, Yoshida T, Ohkubo T, Matsuda S, Iida T, Nakamura S. Structural basis for the toxin-coregulated pilus-dependent secretion of Vibrio cholerae colonization factor. SCIENCE ADVANCES 2022; 8:eabo3013. [PMID: 36240278 PMCID: PMC9565799 DOI: 10.1126/sciadv.abo3013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 08/26/2022] [Indexed: 06/16/2023]
Abstract
Colonization of the host intestine is the most important step in Vibrio cholerae infection. The toxin-coregulated pilus (TCP), an operon-encoded type IVb pilus (T4bP), plays a crucial role in this process, which requires an additional secreted protein, TcpF, encoded on the same TCP operon; however, its mechanisms of secretion and function remain elusive. Here, we demonstrated that TcpF interacts with the minor pilin, TcpB, of TCP and elucidated the crystal structures of TcpB alone and in complex with TcpF. The structural analyses reveal how TCP recognizes TcpF and its secretory mechanism via TcpB-dependent pilus elongation and retraction. Upon binding to TCP, TcpF forms a flower-shaped homotrimer with its flexible N terminus hooked onto the trimeric interface of TcpB. Thus, the interaction between the minor pilin and the N terminus of the secreted protein, namely, the T4bP secretion signal, is key for V. cholerae colonization and is a new potential therapeutic target.
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Affiliation(s)
- Hiroya Oki
- Department of Infection Metagenomics, Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Kazuki Kawahara
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
| | - Minato Iimori
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Yuka Imoto
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Haruka Nishiumi
- Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Takahiro Maruno
- Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Susumu Uchiyama
- Graduate School of Engineering, Osaka University, Osaka, Japan
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Aichi, Japan
- U-Medico Inc., Suita, Osaka, Japan
| | - Yuki Muroga
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Akihiro Yoshida
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Takuya Yoshida
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Tadayasu Ohkubo
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
| | - Shigeaki Matsuda
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Tetsuya Iida
- Department of Infection Metagenomics, Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shota Nakamura
- Department of Infection Metagenomics, Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
- Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Osaka, Japan
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8
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Ronish LA, Sidner B, Yu Y, Piepenbrink KH. Recognition of extracellular DNA by type IV pili promotes biofilm formation by Clostridioides difficile. J Biol Chem 2022; 298:102449. [PMID: 36064001 PMCID: PMC9556784 DOI: 10.1016/j.jbc.2022.102449] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/15/2022] Open
Abstract
Clostridioides difficile is a Gram-positive bacillus, which is a frequent cause of gastrointestinal infections triggered by the depletion of the gut microbiome. Because of the frequent recurrence of these infections after antibiotic treatment, mechanisms of C. difficile persistence and recurrence, including biofilm formation, are of increasing interest. Previously, our group and others found that type IV pili, filamentous helical appendages polymerized from protein subunits, promoted microcolony and biofilm formation in C. difficile. In Gram-negative bacteria, the ability of type IV pili to mediate bacterial self-association has been explained through interactions between the pili of adjacent cells, but type IV pili from several Gram-negative species are also required for natural competence through DNA uptake. Here, we report the ability of two C. difficile pilin subunits, PilJ and PilW, to bind to DNA in vitro, as well as the defects in biofilm formation in the pilJ and pilW gene-interruption mutants. Additionally, we have resolved the X-ray crystal structure of PilW, which we use to model possible structural mechanisms for the formation of C. difficile biofilm through interactions between type IV pili and the DNA of the extracellular matrix. Taken together, our results provide further insight into the relationship between type IV pilus function and biofilm formation in C. difficile and, more broadly, suggest that DNA recognition by type IV pili and related structures may have functional importance beyond DNA uptake for natural competence.
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Affiliation(s)
- Leslie A Ronish
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Ben Sidner
- Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Yafan Yu
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Kurt H Piepenbrink
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
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9
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Abstract
Type IV pili (T4P) are retractable multifunctional nanofibers present on the surface of numerous bacterial and archaeal species. Their importance to microbiology is difficult to overstate. The scientific journey leading to our current understanding of T4P structure and function has included many innovative research milestones. Although multiple T4P reviews over the years have emphasized recent advances, we find that current reports often omit many of the landmark discoveries in this field. Here, we attempt to highlight chronologically the most important work on T4P, from the discovery of pili to the application of sophisticated contemporary methods, which has brought us to our current state of knowledge. As there remains much to learn about the complex machine that assembles and retracts T4P, we hope that this review will increase the interest of current researchers and inspire innovative progress.
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10
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Oliveira V, Aschtgen MS, van Erp A, Henriques-Normark B, Muschiol S. The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae. Front Cell Infect Microbiol 2022; 11:808601. [PMID: 35004361 PMCID: PMC8727766 DOI: 10.3389/fcimb.2021.808601] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 11/30/2021] [Indexed: 12/03/2022] Open
Abstract
The remarkable genomic plasticity of Streptococcus pneumoniae largely depends on its ability to undergo natural genetic transformation. To take up extracellular DNA, S. pneumoniae assembles competence pili composed of the major pilin ComGC. In addition to ComGC, four minor pilins ComGD, E, F, and G are expressed during bacterial competence, but their role in pilus biogenesis and transformation is unknown. Here, using a combination of protein-protein interaction assays we show that all four proteins can directly interact with each other. Pneumococcal ComGG stabilizes the minor pilin ComGD and ComGF and can interact with and stabilize the major pilin ComGC, thus, deletion of ComGG abolishes competence pilus assembly. We further demonstrate that minor pilins are present in sheared pili fractions and find ComGF to be incorporated along the competence pilus by immunofluorescence and electron microscopy. Finally, mutants of the invariant Glu5 residue (E5), ComGDE5A or ComGEE5A, but not ComGFE5A, were severely impaired in pilus formation and function. Together, our results suggest that ComGG, lacking E5, is essential for competence pilus assembly and function, and plays a central role in connecting the pneumococcal minor pilins to ComGC.
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Affiliation(s)
- Vitor Oliveira
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | | | - Anke van Erp
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden
| | - Sandra Muschiol
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden
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11
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Motor-independent retraction of type IV pili is governed by an inherent property of the pilus filament. Proc Natl Acad Sci U S A 2021; 118:2102780118. [PMID: 34789573 DOI: 10.1073/pnas.2102780118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2021] [Indexed: 12/21/2022] Open
Abstract
Type IV pili (T4P) are dynamic surface appendages that promote virulence, biofilm formation, horizontal gene transfer, and motility in diverse bacterial species. Pilus dynamic activity is best characterized in T4P that use distinct ATPase motors for pilus extension and retraction. Many T4P systems, however, lack a dedicated retraction motor, and the mechanism underlying this motor-independent retraction remains a mystery. Using the Vibrio cholerae competence pilus as a model system, we identify mutations in the major pilin gene that enhance motor-independent retraction. These mutants likely diminish pilin-pilin interactions within the filament to produce less-stable pili. One mutation adds a bulky residue to α1C, a universally conserved feature of T4P. We found that inserting a bulky residue into α1C of the retraction motor-dependent Acinetobacter baylyi competence T4P enhances motor-independent retraction. Conversely, removing bulky residues from α1C of the retraction motor-independent, V. cholerae toxin-coregulated T4P stabilizes the filament and diminishes pilus retraction. Furthermore, alignment of pilins from the broader type IV filament (T4F) family indicated that retraction motor-independent T4P, gram-positive Com pili, and type II secretion systems generally encode larger residues within α1C oriented toward the pilus core compared to retraction motor-dependent T4P. Together, our data demonstrate that motor-independent retraction relies, in part, on the inherent instability of the pilus filament, which may be a conserved feature of diverse T4Fs. This provides evidence for a long-standing yet previously untested model in which pili retract in the absence of a motor by spontaneous depolymerization.
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12
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Ellison CK, Whitfield GB, Brun YV. Type IV Pili: Dynamic Bacterial Nanomachines. FEMS Microbiol Rev 2021; 46:6425739. [PMID: 34788436 DOI: 10.1093/femsre/fuab053] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 11/08/2021] [Indexed: 01/19/2023] Open
Abstract
Bacteria and archaea rely on appendages called type IV pili (T4P) to participate in diverse behaviors including surface sensing, biofilm formation, virulence, protein secretion, and motility across surfaces. T4P are broadly distributed fibers that dynamically extend and retract, and this dynamic activity is essential for their function in broad processes. Despite the essentiality of dynamics in T4P function, little is known about the role of these dynamics and molecular mechanisms controlling them. Recent advances in microscopy have yielded insight into the role of T4P dynamics in their diverse functions and recent structural work has expanded what is known about the inner workings of the T4P motor. This review discusses recent progress in understanding the function, regulation, and mechanisms of T4P dynamics.
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Affiliation(s)
- Courtney K Ellison
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Gregory B Whitfield
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Yves V Brun
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Québec, Canada
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13
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Barnier JP, Meyer J, Kolappan S, Bouzinba-Ségard H, Gesbert G, Jamet A, Frapy E, Schönherr-Hellec S, Capel E, Virion Z, Dupuis M, Bille E, Morand P, Schmitt T, Bourdoulous S, Nassif X, Craig L, Coureuil M. The minor pilin PilV provides a conserved adhesion site throughout the antigenically variable meningococcal type IV pilus. Proc Natl Acad Sci U S A 2021; 118:e2109364118. [PMID: 34725157 PMCID: PMC8609321 DOI: 10.1073/pnas.2109364118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/16/2021] [Indexed: 01/14/2023] Open
Abstract
Neisseria meningitidis utilizes type IV pili (T4P) to adhere to and colonize host endothelial cells, a process at the heart of meningococcal invasive diseases leading to meningitis and sepsis. T4P are polymers of an antigenically variable major pilin building block, PilE, plus several core minor pilins that initiate pilus assembly and are thought to be located at the pilus tip. Adhesion of N. meningitidis to human endothelial cells requires both PilE and a conserved noncore minor pilin PilV, but the localization of PilV and its precise role in this process remains to be clarified. Here, we show that both PilE and PilV promote adhesion to endothelial vessels in vivo. The substantial adhesion defect observed for pilV mutants suggests it is the main adhesin. Consistent with this observation, superresolution microscopy showed the abundant distribution of PilV throughout the pilus. We determined the crystal structure of PilV and modeled it within the pilus filament. The small size of PilV causes it to be recessed relative to adjacent PilE subunits, which are dominated by a prominent hypervariable loop. Nonetheless, we identified a conserved surface-exposed adhesive loop on PilV by alanine scanning mutagenesis. Critically, antibodies directed against PilV inhibit N. meningitidis colonization of human skin grafts. These findings explain how N. meningitidis T4P undergo antigenic variation to evade the humoral immune response while maintaining their adhesive function and establish the potential of this highly conserved minor pilin as a vaccine and therapeutic target for the prevention and treatment of N. meningitidis infections.
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Affiliation(s)
- Jean-Philippe Barnier
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
- Service de Microbiologie, Assistance Publique-Hôpitaux de Paris, Centre-Université de Paris, Hôpital Necker Enfants-Malades, Paris 75015, France
| | - Julie Meyer
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Subramania Kolappan
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 3Y6, Canada
| | - Haniaa Bouzinba-Ségard
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1016, CNRS UMR 8104, Institut Cochin, Paris 75014, France
| | - Gaël Gesbert
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Anne Jamet
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
- Service de Microbiologie, Assistance Publique-Hôpitaux de Paris, Centre-Université de Paris, Hôpital Necker Enfants-Malades, Paris 75015, France
| | - Eric Frapy
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Sophia Schönherr-Hellec
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Elena Capel
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Zoé Virion
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Marion Dupuis
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
| | - Emmanuelle Bille
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
- Service de Microbiologie, Assistance Publique-Hôpitaux de Paris, Centre-Université de Paris, Hôpital Necker Enfants-Malades, Paris 75015, France
| | - Philippe Morand
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
- Service de Bactériologie, Assistance Publique-Hôpitaux de Paris, Centre-Université de Paris, Hôpital Cochin, Paris 75014, France
| | - Taliah Schmitt
- Service de Chirurgie Reconstructrice et Plastique, Groupe Hospitalier Paris Saint-Joseph, Paris 75014, France
| | - Sandrine Bourdoulous
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1016, CNRS UMR 8104, Institut Cochin, Paris 75014, France
| | - Xavier Nassif
- Faculté de Médecine, Université de Paris, Paris 75006, France
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
- Service de Microbiologie, Assistance Publique-Hôpitaux de Paris, Centre-Université de Paris, Hôpital Necker Enfants-Malades, Paris 75015, France
| | - Lisa Craig
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 3Y6, Canada;
| | - Mathieu Coureuil
- Faculté de Médecine, Université de Paris, Paris 75006, France;
- INSERM U1151, CNRS UMR 8253, Institut Necker Enfants-Malades, Paris 75015, France
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14
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Exploiting pilus-mediated bacteria-host interactions for health benefits. Mol Aspects Med 2021; 81:100998. [PMID: 34294411 DOI: 10.1016/j.mam.2021.100998] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/30/2021] [Accepted: 07/16/2021] [Indexed: 02/06/2023]
Abstract
Surface pili (or fimbriae) are an important but conspicuous adaptation of several genera and species of Gram-negative and Gram-positive bacteria. These long and non-flagellar multi-subunit adhesins mediate the initial contact that a bacterium has with a host or environment, and thus have come to be regarded as a key colonization factor for virulence activity in pathogens or niche adaptation in commensals. Pili in pathogenic bacteria are well recognized for their roles in the adhesion to host cells, colonization of tissues, and establishment of infection. As an 'anti-adhesive' ploy, targeting pilus-mediated attachment for disruption has become a potentially effective alternative to using antibiotics. In this review, we give a description of the several structurally distinct bacterial pilus types thus far characterized, and as well offer details about the intricacy of their individual structure, assembly, and function. With a molecular understanding of pilus biogenesis and pilus-mediated host interactions also provided, we go on to describe some of the emerging new approaches and compounds that have been recently developed to prevent the adhesion, colonization, and infection of piliated bacterial pathogens.
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15
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Chlebek JL, Dalia TN, Biais N, Dalia AB. Fresh Extension of Vibrio cholerae Competence Type IV Pili Predisposes Them for Motor-Independent Retraction. Appl Environ Microbiol 2021; 87:e0047821. [PMID: 33990308 PMCID: PMC8231728 DOI: 10.1128/aem.00478-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/06/2021] [Indexed: 11/20/2022] Open
Abstract
Bacteria utilize dynamic appendages, called type IV pili (T4P), to interact with their environment and mediate a wide variety of functions. Pilus extension is mediated by an extension ATPase motor, commonly called PilB, in all T4P. Pilus retraction, however, can occur with the aid of an ATPase motor or in the absence of a retraction motor. While much effort has been devoted to studying motor-dependent retraction, the mechanism and regulation of motor-independent retraction remain poorly characterized. We have previously demonstrated that Vibrio cholerae competence T4P undergo motor-independent retraction in the absence of the dedicated retraction ATPases PilT and PilU. Here, we utilize this model system to characterize the factors that influence motor-independent retraction. We find that freshly extended pili frequently undergo motor-independent retraction, but if these pili fail to retract immediately, they remain statically extended on the cell surface. Importantly, we show that these static pili can still undergo motor-dependent retraction via tightly regulated ectopic expression of PilT, suggesting that these T4P are not broken but simply cannot undergo motor-independent retraction. Through additional genetic and biophysical characterization of pili, we suggest that pilus filaments undergo conformational changes during dynamic extension and retraction. We propose that only some conformations, like those adopted by freshly extended pili, are capable of undergoing motor-independent retraction. Together, these data highlight the versatile mechanisms that regulate T4P dynamic activity and provide additional support for the long-standing hypothesis that motor-independent retraction occurs via spontaneous depolymerization. IMPORTANCE Extracellular pilus fibers are critical to the virulence and persistence of many pathogenic bacteria. A crucial function for most pili is the dynamic ability to extend and retract from the cell surface. Inhibiting this dynamic pilus activity represents an attractive approach for therapeutic interventions; however, a detailed mechanistic understanding of this process is currently lacking. Here, we use the competence pilus of Vibrio cholerae to study how pili retract in the absence of dedicated retraction motors. Our results reveal a novel regulatory mechanism of pilus retraction that is an inherent property of the pilus filament. Thus, understanding the conformational changes that pili adopt under different conditions may be critical for the development of novel therapeutics that aim to target the dynamic activity of these structures.
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Affiliation(s)
| | - Triana N. Dalia
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Nicolas Biais
- Biology Department and Graduate Center, City University of New York, Brooklyn, New York, USA
- Laboratoire Jean Perrin, UMR 8237 Sorbonne Université/CNRS, Paris, France
| | - Ankur B. Dalia
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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16
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Structural interactions define assembly adapter function of a type II secretion system pseudopilin. Structure 2021; 29:1116-1127.e8. [PMID: 34139172 DOI: 10.1016/j.str.2021.05.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/15/2021] [Accepted: 05/28/2021] [Indexed: 01/13/2023]
Abstract
The type IV filament superfamily comprises widespread membrane-associated polymers in prokaryotes. The type II secretion system (T2SS), a virulence pathway in many pathogens, belongs to this superfamily. A knowledge gap in understanding of the T2SS is the molecular role of a small "pseudopilin" protein. Using multiple biophysical techniques, we have deciphered how this missing component of the Xcp T2SS architecture is structurally integrated, and thereby unlocked its function. We demonstrate that low-abundance XcpH is the adapter that bridges a trimeric initiating tip complex, XcpIJK, with a periplasmic filament of XcpG subunits. Each pseudopilin protein caps an XcpG protofilament in an overall pseudopilus compatible with dimensions of the periplasm and the outer membrane-spanning secretin through which substrates pass. Unexpectedly, to fulfill its adapter function, the XcpH N-terminal helix must be unwound, a property shared with XcpG subunits. We provide an experimentally validated three-dimensional structural model of a complete type IV filament.
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17
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Oeser S, Wallner T, Schuergers N, Bučinská L, Sivabalasarma S, Bähre H, Albers SV, Wilde A. Minor pilins are involved in motility and natural competence in the cyanobacterium Synechocystis sp. PCC 6803. Mol Microbiol 2021; 116:743-765. [PMID: 34115422 DOI: 10.1111/mmi.14768] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 06/04/2021] [Accepted: 06/05/2021] [Indexed: 11/28/2022]
Abstract
Cyanobacteria synthesize type IV pili, which are known to be essential for motility, adhesion and natural competence. They consist of long flexible fibers that are primarily composed of the major pilin PilA1 in Synechocystis sp. PCC 6803. In addition, Synechocystis encodes less abundant pilin-like proteins, which are known as minor pilins. In this study, we show that the minor pilin PilA5 is essential for natural transformation but is dispensable for motility and flocculation. In contrast, a set of minor pilins encoded by the pilA9-slr2019 transcriptional unit are necessary for motility but are dispensable for natural transformation. Neither pilA5-pilA6 nor pilA9-slr2019 are essential for pilus assembly as mutant strains showed type IV pili on the cell surface. Three further gene products with similarity to PilX-like minor pilins have a function in flocculation of Synechocystis. The results of our study indicate that different minor pilins facilitate distinct pilus functions. Further, our microarray analysis demonstrated that the transcription levels of the minor pilin genes change in response to surface contact. A total of 122 genes were determined to have altered transcription between planktonic and surface growth, including several plasmid genes which are involved exopolysaccharide synthesis and the formation of bloom-like aggregates.
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Affiliation(s)
- Sabrina Oeser
- Molecular Genetics, Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Thomas Wallner
- Molecular Genetics, Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Nils Schuergers
- Molecular Genetics, Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Lenka Bučinská
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Trebon, Czech Republic
| | - Shamphavi Sivabalasarma
- Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Heike Bähre
- Research Core Unit Metabolomics, Medical School Hannover, Hannover, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Annegret Wilde
- Molecular Genetics, Institute of Biology III, University of Freiburg, Freiburg, Germany
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18
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Abstract
Biofilms are structured communities formed by a single or multiple microbial species. Within biofilms, bacteria are embedded into extracellular matrix, allowing them to build macroscopic objects. Biofilm structure can respond to environmental changes such as the presence of antibiotics or predators. By adjusting expression levels of surface and extracellular matrix components, bacteria tune cell-to-cell interactions. One major challenge in the field is the fact that these components are very diverse among different species. Deciphering how physical interactions within biofilms are affected by changes in gene expression is a promising approach to obtaining a more unified picture of how bacteria modulate biofilms. This review focuses on recent advances in characterizing attractive and repulsive forces between bacteria in correlation with biofilm structure, dynamics, and spreading. How bacteria control physical interactions to maximize their fitness is an emerging theme.
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Affiliation(s)
- Berenike Maier
- Institute for Biological Physics and Center for Molecular Medicine Cologne, University of Cologne, 50674 Cologne, Germany;
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19
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Naskar S, Hohl M, Tassinari M, Low HH. The structure and mechanism of the bacterial type II secretion system. Mol Microbiol 2020; 115:412-424. [PMID: 33283907 DOI: 10.1111/mmi.14664] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/03/2020] [Indexed: 12/17/2022]
Abstract
The type II secretion system (T2SS) is a multi-protein complex used by many bacteria to move substrates across their cell membrane. Substrates released into the environment serve as local and long-range effectors that promote nutrient acquisition, biofilm formation, and pathogenicity. In both animals and plants, the T2SS is increasingly recognized as a key driver of virulence. The T2SS spans the bacterial cell envelope and extrudes substrates through an outer membrane secretin channel using a pseudopilus. An inner membrane assembly platform and a cytoplasmic motor controls pseudopilus assembly. This microreview focuses on the structure and mechanism of the T2SS. Advances in cryo-electron microscopy are enabling increasingly elaborate sub-complexes to be resolved. However, key questions remain regarding the mechanism of pseudopilus extension and retraction, and how this is coupled with the choreography of the substrate moving through the secretion system. The T2SS is part of an ancient type IV filament superfamily that may have been present within the last universal common ancestor (LUCA). Overall, mechanistic principles that underlie T2SS function have implication for other closely related systems such as the type IV and tight adherence pilus systems.
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Affiliation(s)
- Souvik Naskar
- Department of Infectious Disease, Imperial College, London, UK
| | - Michael Hohl
- Department of Infectious Disease, Imperial College, London, UK
| | | | - Harry H Low
- Department of Infectious Disease, Imperial College, London, UK
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20
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Graham KJ, Burrows LL. More than a feeling: microscopy approaches to understanding surface-sensing mechanisms. J Bacteriol 2020; 203:JB.00492-20. [PMID: 33077631 PMCID: PMC8095462 DOI: 10.1128/jb.00492-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The mechanisms by which bacteria sense and respond to surface attachment have long been a mystery. Our understanding of the structure and dynamics of bacterial appendages, notably type IV pili (T4P), provided new insights into the potential ways that bacteria sense surfaces. T4P are ubiquitous, retractable hair-like adhesins that until recently were difficult to image in the absence of fixation due to their nanoscale size. This review focuses on recent microscopy innovations used to visualize T4P in live cells to reveal the dynamics of their retraction and extension. We discuss recently proposed mechanisms by which T4P facilitate bacterial surface sensing, including the role of surface-exposed PilY1, two-component signal transduction pathways, force-induced structural modifications of the major pilin, and altered dynamics of the T4P motor complex.
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Affiliation(s)
- Katherine J Graham
- Department of Biochemistry and Biomedical Sciences, and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton ON Canada L8S4K1
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences, and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton ON Canada L8S4K1
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21
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González Plaza JJ. Small RNAs as Fundamental Players in the Transference of Information During Bacterial Infectious Diseases. Front Mol Biosci 2020; 7:101. [PMID: 32613006 PMCID: PMC7308464 DOI: 10.3389/fmolb.2020.00101] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 05/04/2020] [Indexed: 12/24/2022] Open
Abstract
Communication shapes life on Earth. Transference of information has played a paramount role on the evolution of all living or extinct organisms since the appearance of life. Success or failure in this process will determine the prevalence or disappearance of a certain set of genes, the basis of Darwinian paradigm. Among different molecules used for transmission or reception of information, RNA plays a key role. For instance, the early precursors of life were information molecules based in primitive RNA forms. A growing field of research has focused on the contribution of small non-coding RNA forms due to its role on infectious diseases. These are short RNA species that carry out regulatory tasks in cis or trans. Small RNAs have shown their relevance in fine tuning the expression and activity of important regulators of essential genes for bacteria. Regulation of targets occurs through a plethora of mechanisms, including mRNA stabilization/destabilization, driving target mRNAs to degradation, or direct binding to regulatory proteins. Different studies have been conducted during the interplay of pathogenic bacteria with several hosts, including humans, animals, or plants. The sRNAs help the invader to quickly adapt to the change in environmental conditions when it enters in the host, or passes to a free state. The adaptation is achieved by direct targeting of the pathogen genes, or subversion of the host immune system. Pathogens trigger also an immune response in the host, which has been shown as well to be regulated by a wide range of sRNAs. This review focuses on the most recent host-pathogen interaction studies during bacterial infectious diseases, providing the perspective of the pathogen.
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Affiliation(s)
- Juan José González Plaza
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague, Czechia
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22
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van Wolferen M, Shajahan A, Heinrich K, Brenzinger S, Black IM, Wagner A, Briegel A, Azadi P, Albers SV. Species-Specific Recognition of Sulfolobales Mediated by UV-Inducible Pili and S-Layer Glycosylation Patterns. mBio 2020; 11:e03014-19. [PMID: 32156822 PMCID: PMC7064770 DOI: 10.1128/mbio.03014-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/21/2020] [Indexed: 01/07/2023] Open
Abstract
The UV-inducible pili system of Sulfolobales (Ups) mediates the formation of species-specific cellular aggregates. Within these aggregates, cells exchange DNA to repair DNA double-strand breaks via homologous recombination. Substitution of the Sulfolobus acidocaldarius pilin subunits UpsA and UpsB with their homologs from Sulfolobus tokodaii showed that these subunits facilitate species-specific aggregation. A region of low conservation within the UpsA homologs is primarily important for this specificity. Aggregation assays in the presence of different sugars showed the importance of N-glycosylation in the recognition process. In addition, the N-glycan decorating the S-layer of S. tokodaii is different from the one of S. acidocaldarius Therefore, each Sulfolobus species seems to have developed a unique UpsA binding pocket and unique N-glycan composition to ensure aggregation and, consequently, also DNA exchange with cells from only the same species, which is essential for DNA repair by homologous recombination.IMPORTANCE Type IV pili can be found on the cell surface of many archaea and bacteria where they play important roles in different processes. The UV-inducible pili system of Sulfolobales (Ups) pili from the crenarchaeal Sulfolobales species are essential in establishing species-specific mating partners, thereby assisting in genome stability. With this work, we show that different Sulfolobus species have specific regions in their Ups pili subunits, which allow them to interact only with cells from the same species. Additionally, different Sulfolobus species have unique surface-layer N-glycosylation patterns. We propose that the unique features of each species allow the recognition of specific mating partners. This knowledge for the first time gives insights into the molecular basis of archaeal self-recognition.
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Affiliation(s)
- Marleen van Wolferen
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, University of Freiburg, Freiburg, Germany
| | - Asif Shajahan
- Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA
| | - Kristina Heinrich
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, University of Freiburg, Freiburg, Germany
| | | | - Ian M Black
- Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA
| | - Alexander Wagner
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, University of Freiburg, Freiburg, Germany
| | - Ariane Briegel
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia, USA
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
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23
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Ligthart K, Belzer C, de Vos WM, Tytgat HLP. Bridging Bacteria and the Gut: Functional Aspects of Type IV Pili. Trends Microbiol 2020; 28:340-348. [PMID: 32298612 DOI: 10.1016/j.tim.2020.02.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/31/2020] [Accepted: 02/10/2020] [Indexed: 12/14/2022]
Abstract
Cell-surface-located proteinaceous appendages, such as flagella and fimbriae or pili, are ubiquitous in bacterial communities. Here, we focus on conserved type IV pili (T4P) produced by bacteria in the intestinal tract, one of the most densely populated human ecosystems. Computational analysis revealed that approximately 30% of known intestinal bacteria are predicted to produce T4P. To rationalize how T4P allow intestinal bacteria to interact with their environment, other microbiota members, and host cells, we review their established role in gut commensals and pathogens with respect to adherence, motility, and biofilm formation, as well as protein secretion and DNA uptake. This work indicates that T4P are widely spread among the known members of the intestinal microbiota and that their contribution to human health might be underestimated.
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Affiliation(s)
- Kate Ligthart
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
| | - Clara Belzer
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
| | - Willem M de Vos
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands; Research Program Human Microbiome, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Hanne L P Tytgat
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
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24
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Decoupling Filamentous Phage Uptake and Energy of the TolQRA Motor in Escherichia coli. J Bacteriol 2020; 202:JB.00428-19. [PMID: 31636109 DOI: 10.1128/jb.00428-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 10/18/2019] [Indexed: 12/15/2022] Open
Abstract
Filamentous phages are nonlytic viruses that specifically infect bacteria, establishing a persistent association with their host. The phage particle has no machinery for generating energy and parasitizes its host's existing structures in order to cross the bacterial envelope and deliver its genetic material. The import of filamentous phages across the bacterial periplasmic space requires some of the components of a macrocomplex of the envelope known as the Tol system. This complex uses the energy provided by the proton motive force (pmf) of the inner membrane to perform essential and highly energy-consuming functions of the cell, such as envelope integrity maintenance and cell division. It has been suggested that phages take advantage of pmf-driven conformational changes in the Tol system to transit across the periplasm. However, this hypothesis has not been formally tested. In order to decouple the role of the Tol system in cell physiology and during phage parasitism, we used mutations on conserved essential residues known for inactivating pmf-dependent functions of the Tol system. We identified impaired Tol complexes that remain fully efficient for filamentous phage uptake. We further demonstrate that the TolQ-TolR homologous motor ExbB-ExbD, normally operating with the TonB protein, is able to promote phage infection along with full-length TolA.IMPORTANCE Filamentous phages are widely distributed symbionts of Gram-negative bacteria, with some of them being linked to genome evolution and virulence of their host. However, the precise mechanism that permits their uptake across the cell envelope is poorly understood. The canonical phage model Fd requires the TolQRA protein complex in the host envelope, which is suspected to translocate protons across the inner membrane. In this study, we show that phage uptake proceeds in the presence of the assembled but nonfunctional TolQRA complex. Moreover, our results unravel an alternative route for phage import that relies on the ExbB-ExbD proteins. This work provides new insights into the fundamental mechanisms of phage infection and might be generalized to other filamentous phages responsible for pathogen emergence.
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25
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Ellison CK, Kan J, Chlebek JL, Hummels KR, Panis G, Viollier PH, Biais N, Dalia AB, Brun YV. A bifunctional ATPase drives tad pilus extension and retraction. SCIENCE ADVANCES 2019; 5:eaay2591. [PMID: 31897429 PMCID: PMC6920026 DOI: 10.1126/sciadv.aay2591] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 10/21/2019] [Indexed: 06/10/2023]
Abstract
A widespread class of prokaryotic motors powered by secretion motor adenosine triphosphatases (ATPases) drives the dynamic extension and retraction of extracellular fibers, such as type IV pili (T4P). Among these, the tight adherence (tad) pili are critical for surface sensing and biofilm formation. As for most other motors belonging to this class, how tad pili retract despite lacking a dedicated retraction motor ATPase has remained a mystery. Here, we find that a bifunctional pilus motor ATPase, CpaF, drives both activities through adenosine 5'-triphosphate (ATP) hydrolysis. We show that mutations within CpaF result in a correlated reduction in the rates of extension and retraction that directly scales with decreased ATP hydrolysis and retraction force. Thus, a single motor ATPase drives the bidirectional processes of pilus fiber extension and retraction.
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Affiliation(s)
- Courtney K. Ellison
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN 47405, USA
| | - Jingbo Kan
- Biology Department, CUNY Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Graduate Center of CUNY, 365 5th Avenue, New York, NY 10016, USA
| | - Jennifer L. Chlebek
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN 47405, USA
| | - Katherine R. Hummels
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN 47405, USA
| | - Gaёl Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick H. Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Nicolas Biais
- Biology Department, CUNY Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Graduate Center of CUNY, 365 5th Avenue, New York, NY 10016, USA
| | - Ankur B. Dalia
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN 47405, USA
| | - Yves V. Brun
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN 47405, USA
- Département de microbiologie, Infectiologie et Immunologie, Université de Montréal, succursale Centre-ville, Montréal, H3C 3J7 Quebec, Canada
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26
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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: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [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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27
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McCallum M, Benlekbir S, Nguyen S, Tammam S, Rubinstein JL, Burrows LL, Howell PL. Multiple conformations facilitate PilT function in the type IV pilus. Nat Commun 2019; 10:5198. [PMID: 31729381 PMCID: PMC6858323 DOI: 10.1038/s41467-019-13070-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 10/18/2019] [Indexed: 12/13/2022] Open
Abstract
Type IV pilus-like systems are protein complexes that polymerize pilin fibres. They are critical for virulence in many bacterial pathogens. Pilin polymerization and depolymerization are powered by motor ATPases of the PilT/VirB11-like family. This family is thought to operate with C2 symmetry; however, most of these ATPases crystallize with either C3 or C6 symmetric conformations. The relevance of these conformations is unclear. Here, we determine the X-ray structures of PilT in four unique conformations and use these structures to classify the conformation of available PilT/VirB11-like family member structures. Single particle electron cryomicroscopy (cryoEM) structures of PilT reveal condition-dependent preferences for C2, C3, and C6 conformations. The physiologic importance of these conformations is validated by coevolution analysis and functional studies of point mutants, identifying a rare gain-of-function mutation that favours the C2 conformation. With these data, we propose a comprehensive model of PilT function with broad implications for PilT/VirB11-like family members.
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Affiliation(s)
- Matthew McCallum
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Program in Molecular Structure & Function, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Samir Benlekbir
- Program in Molecular Structure & Function, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Sheryl Nguyen
- Program in Molecular Structure & Function, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Stephanie Tammam
- Program in Molecular Structure & Function, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - John L Rubinstein
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Program in Molecular Structure & Function, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.
- Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1l7, Canada.
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, L8S 4K1, Canada.
| | - P Lynne Howell
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Program in Molecular Structure & Function, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.
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28
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The quorum sensing transcription factor AphA directly regulates natural competence in Vibrio cholerae. PLoS Genet 2019; 15:e1008362. [PMID: 31658256 PMCID: PMC6855506 DOI: 10.1371/journal.pgen.1008362] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/14/2019] [Accepted: 10/16/2019] [Indexed: 01/30/2023] Open
Abstract
Many bacteria use population density to control gene expression via quorum sensing. In Vibrio cholerae, quorum sensing coordinates virulence, biofilm formation, and DNA uptake by natural competence. The transcription factors AphA and HapR, expressed at low and high cell density respectively, play a key role. In particular, AphA triggers the entire virulence cascade upon host colonisation. In this work we have mapped genome-wide DNA binding by AphA. We show that AphA is versatile, exhibiting distinct modes of DNA binding and promoter regulation. Unexpectedly, whilst HapR is known to induce natural competence, we demonstrate that AphA also intervenes. Most notably, AphA is a direct repressor of tfoX, the master activator of competence. Hence, production of AphA markedly suppressed DNA uptake; an effect largely circumvented by ectopic expression of tfoX. Our observations suggest dual regulation of competence. At low cell density AphA is a master repressor whilst HapR activates the process at high cell density. Thus, we provide deep mechanistic insight into the role of AphA and highlight how V. cholerae utilises this regulator for diverse purposes. Cholera remains a devastating diarrhoeal disease responsible for millions of cases, thousands of deaths, and a $3 billion financial burden every year. Although notorious for causing human disease, the microorganism responsible for cholera is predominantly a resident of aquatic environments. Here, the organism survives in densely packed communities on the surfaces of crustaceans. Remarkably, in this situation, the microbe can feast on neighbouring cells and acquire their DNA. This provides a useful food source and an opportunity to obtain new genetic information. In this paper, we have investigated how acquisition of DNA from the local environment is regulated. We show that a “switch” within the microbial cell, known to activate disease processes in the human host, also controls DNA uptake. Our results explain why DNA scavenging only occurs in suitable environments and illustrates how interactions between common regulatory switches affords precise control of microbial behaviours.
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29
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Zöllner R, Cronenberg T, Maier B. Motor Properties of PilT-Independent Type 4 Pilus Retraction in Gonococci. J Bacteriol 2019; 201:e00778-18. [PMID: 30692169 PMCID: PMC6707916 DOI: 10.1128/jb.00778-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 01/17/2019] [Indexed: 01/25/2023] Open
Abstract
Bacterial type 4 pili (T4P) belong to the strongest molecular machines. The gonococcal T4P retraction ATPase PilT supports forces exceeding 100 pN during T4P retraction. Here, we address the question of whether gonococcal T4P retract in the absence of PilT. We show that pilT deletion strains indeed retract their T4P, but the maximum force is reduced to 5 pN. Similarly, the speed of T4P retraction is lower by orders of magnitude compared to that of T4P retraction driven by PilT. Deleting the pilT paralogue pilT2 further reduces the speed of T4P retraction, yet T4P retraction is detectable in the absence of all three pilT paralogues. Furthermore, we show that depletion of proton motive force (PMF) slows but does not inhibit pilT-independent T4P retraction. We conclude that the retraction ATPase is not essential for gonococcal T4P retraction. However, the force generated in the absence of PilT is too low to support important functions of T4P, including twitching motility, fluidization of colonies, and induction of host cell response.IMPORTANCE Bacterial type 4 pili (T4P) have been termed the "Swiss Army knives" of bacteria because they perform numerous functions, including host cell interaction, twitching motility, colony formation, DNA uptake, protein secretion, and surface sensing. The pilus fiber continuously elongates or retracts, and these dynamics are functionally important. Curiously, only a subset of T4P systems employ T4P retraction ATPases to power T4P retraction. Here, we show that one of the strongest T4P machines, the gonococcal T4P, retracts without a retraction ATPase. Biophysical characterization reveals strongly reduced force and speed compared to retraction with ATPase. We propose that bacteria encode retraction ATPases when T4P have to generate high-force-supporting functions like twitching motility, triggering host cell response, or fluidizing colonies.
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Affiliation(s)
- Robert Zöllner
- University of Cologne, Institute for Biological Physics, Cologne, Germany
| | - Tom Cronenberg
- University of Cologne, Institute for Biological Physics, Cologne, Germany
| | - Berenike Maier
- University of Cologne, Institute for Biological Physics, Cologne, Germany
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30
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Gutierrez-Rodarte M, Kolappan S, Burrell BA, Craig L. The Vibrio cholerae minor pilin TcpB mediates uptake of the cholera toxin phage CTXφ. J Biol Chem 2019; 294:15698-15710. [PMID: 31471320 DOI: 10.1074/jbc.ra119.009980] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/27/2019] [Indexed: 12/13/2022] Open
Abstract
Virulent strains of the bacterial pathogen Vibrio cholerae cause the diarrheal disease cholera by releasing cholera toxin into the small intestine. V. cholerae acquired its cholera toxin genes by lysogenic infection with the filamentous bacteriophage CTXφ. CTXφ uses its minor coat protein pIII, located in multiple copies at the phage tip, to bind to the V. cholerae toxin-coregulated pilus (TCP). However, the molecular details of this interaction and the mechanism of phage internalization are not well-understood. The TCP filament is a polymer of major pilins, TcpA, and one or more minor pilin, TcpB. TCP are retractile, with both retraction and assembly initiated by TcpB. Consistent with these roles in pilus dynamics, we hypothesized that TcpB controls both binding and internalization of CTXφ. To test this hypothesis, we determined the crystal structure of the C-terminal half of TcpB and characterized its interactions with CTXφ pIII. We show that TcpB is a homotrimer in its crystallographic form as well as in solution and is present in multiple copies at the pilus tip, which likely facilitates polyvalent binding to pIII proteins at the phage tip. We further show that recombinant forms of TcpB and pIII interact in vitro, and both TcpB and anti-TcpB antibodies block CTXφ infection of V. cholerae Finally, we show that CTXφ uptake requires TcpB-mediated retraction. Our data support a model whereby CTXφ and TCP bind in a tip-to-tip orientation, allowing the phage to be drawn into the V. cholerae periplasm as an extension of the pilus filament.
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Affiliation(s)
- Miguel Gutierrez-Rodarte
- Molecular Biology and Biochemistry Department, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Subramania Kolappan
- Molecular Biology and Biochemistry Department, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Bailey A Burrell
- Molecular Biology and Biochemistry Department, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Lisa Craig
- Molecular Biology and Biochemistry Department, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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31
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Abstract
Bacterial surface attachment is mediated by filamentous appendages called pili. Here, we describe the role of Tad pili during surface colonization of Caulobacter crescentus Using an optical trap and microfluidic controlled flow conditions to mimic natural environments, we demonstrated that Tad pili undergo repeated dynamic cycles of extension and retraction. Within seconds after establishing surface contact, pilus retraction reorients cells into an upright position, promoting walking-like movements against the medium flow. Pilus-mediated positioning of the flagellate pole close to the surface facilitates motor-mediated mechanical sensing and promotes anchoring of the holdfast, an adhesive substance that affords long-term attachment. We present evidence that the second messenger c-di-GMP regulates pilus dynamics during surface encounter in distinct ways, promoting increased activity at intermediate levels and retraction of pili at peak concentrations. We propose a model in which flagellum and Tad pili functionally interact and together impose a ratchet-like mechanism that progressively drives C. crescentus cells toward permanent surface attachment.IMPORTANCE Bacteria are able to colonize surfaces in environmental, industrial, and medical settings, where they form resilient communities called biofilms. In order to control bacterial surface colonization, microbiologists need to gain a detailed understanding of the processes that bacteria use to live at the liquid-surface interface and that allow them to adhere to and move on surfaces and eventually grow and persist on solid media. To facilitate these processes, bacteria are equipped with adhesive structures such as flagella and pili and with matrix components such as exopolysaccharides. How these cellular organelles are coordinated to optimize surface processes is currently subject to intense investigations. Here we used the model organism Caulobacter crescentus to demonstrate that polar pili are highly dynamic structures that are functionally interconnected with the flagellar motor to mediate surface sensing, thereby enforcing rapid and permanent surface attachment. These studies provide an entry point for an in-depth molecular analysis of bacterial surface colonization.
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32
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Ellison CK, Dalia TN, Dalia AB, Brun YV. Real-time microscopy and physical perturbation of bacterial pili using maleimide-conjugated molecules. Nat Protoc 2019; 14:1803-1819. [PMID: 31028374 DOI: 10.1038/s41596-019-0162-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/05/2019] [Indexed: 11/09/2022]
Abstract
Bacteria use surface-exposed, proteinaceous fibers called pili for diverse behaviors, including horizontal gene transfer, surface sensing, motility, and pathogenicity. Visualization of these filamentous nanomachines and their activity in live cells has proven challenging, largely due to their small size. Here, we describe a broadly applicable method for labeling and imaging pili and other surface-exposed nanomachines in live cells. This technique uses a combination of genetics and maleimide-based click chemistry in which a cysteine substitution is made in the major pilin subunit for subsequent labeling with thiol-reactive maleimide dyes. Large maleimide-conjugated molecules can also be used to physically interfere with the dynamic activity of filamentous nanomachines. We describe parameters for selecting cysteine substitution positions, optimized labeling conditions for epifluorescence imaging of pilus fibers, and methods for impeding pilus activity. After cysteine knock-in strains have been generated, this protocol can be completed within 30 min to a few hours, depending on the species and the experiment of choice. Visualization of extracellular nanomachines such as pili using this approach can provide a more comprehensive understanding of the role played by these structures in distinct bacterial behaviors.
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Affiliation(s)
| | - Triana N Dalia
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Ankur B Dalia
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Yves V Brun
- Department of Biology, Indiana University, Bloomington, IN, USA. .,Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada.
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33
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Abstract
Type IV pilus (T4P)-like systems have been identified in almost every major phylum of prokaryotic life. They include the type IVa pilus (T4aP), type II secretion system (T2SS), type IVb pilus (T4bP), Tad/Flp pilus, Com pilus, and archaeal flagellum (archaellum). These systems are used for adhesion, natural competence, phage adsorption, folded-protein secretion, surface sensing, swimming motility, and twitching motility. The T4aP allows for all of these functions except swimming and is therefore a good model system for understanding T4P-like systems. Recent structural analyses have revolutionized our understanding of how the T4aP machinery assembles and functions. Here we review the structure and function of the T4aP.
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34
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Abstract
ABSTRACT
Type IV pili (T4P) are remarkable bacterial surface appendages that carry out a range of functions. Various types of T4P have been identified in bacteria and archaea, making them almost universal structures in prokaryotes. T4P are best characterized in Gram-negative bacteria, in which pilus biogenesis and T4P-mediated functions have been studied for decades. Recent advances in microbial whole-genome sequencing have provided ample evidence for the existence of T4P also in many Gram-positive species. However, comparatively little is known, and T4P in Gram-positive bacteria are just beginning to be dissected. So far, they have mainly been studied in
Clostridium
and
Streptococcus
spp. and are involved in diverse cellular processes such as adhesion, motility, and horizontal gene transfer. Here we summarize the current understanding of T4P in Gram-positive species and their functions, with particular focus on the type IV competence pilus produced by the human pathogen
Streptococcus pneumoniae
and its role in natural transformation.
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35
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Abstract
Bacterial uptake of DNA through type IV filaments is an essential component of natural competence in numerous gram-positive and gram-negative species. Recent advances in the field have broadened our understanding of the structures used to take up extracellular DNA. Here, we review seminal experiments in the literature describing DNA binding by type IV pili, competence pili and the flp pili of Micrococcus luteus; collectively referred to here as type IV filaments. We compare the current state of the field on mechanisms of DNA uptake for these three appendage systems and describe the current mechanistic understanding of both DNA-binding and DNA-uptake by these versatile molecular machines.
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Affiliation(s)
- Kurt H Piepenbrink
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, United States.,Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, United States.,Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, NE, United States.,Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE, United States
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36
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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] [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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37
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Duché D, Houot L. Similarities and Differences between Colicin and Filamentous Phage Uptake by Bacterial Cells. EcoSal Plus 2019; 8. [PMID: 30681066 DOI: 10.1128/ecosalplus.esp-0030-2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Indexed: 06/09/2023]
Abstract
Gram-negative bacteria have evolved a complex envelope to adapt and survive in a broad range of ecological niches. This physical barrier is the first line of defense against noxious compounds and viral particles called bacteriophages. Colicins are a family of bactericidal proteins produced by and toxic to Escherichia coli and closely related bacteria. Filamentous phages have a complex structure, composed of at least five capsid proteins assembled in a long thread-shaped particle, that protects the viral DNA. Despite their difference in size and complexity, group A colicins and filamentous phages both parasitize multiprotein complexes of their sensitive host for entry. They first bind to a receptor located at the surface of the target bacteria before specifically recruiting components of the Tol system to cross the outer membrane and find their way through the periplasm. The Tol system is thought to use the proton motive force of the inner membrane to maintain outer membrane integrity during the life cycle of the cell. This review describes the sequential docking mechanisms of group A colicins and filamentous phages during their uptake by their bacterial host, with a specific focus on the translocation step, promoted by interactions with the Tol system.
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Affiliation(s)
- Denis Duché
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 13402 Marseille, France
| | - Laetitia Houot
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université- CNRS, 13402 Marseille, France
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38
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Ronish LA, Lillehoj E, Fields JK, Sundberg EJ, Piepenbrink KH. The structure of PilA from Acinetobacter baumannii AB5075 suggests a mechanism for functional specialization in Acinetobacter type IV pili. J Biol Chem 2018; 294:218-230. [PMID: 30413536 DOI: 10.1074/jbc.ra118.005814] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/19/2018] [Indexed: 11/06/2022] Open
Abstract
Type IV pili (T4P) are bacterial appendages composed of protein subunits, called pilins, noncovalently assembled into helical fibers. T4P are essential, in many bacterial species, for processes as diverse as twitching motility, natural competence, biofilm or microcolony formation, and host cell adhesion. The genes encoding type IV pili are found universally in the Gram-negative, aerobic, nonflagellated, and pathogenic coccobacillus Acinetobacter baumannii, but there is considerable variation in PilA, the major protein subunit, both in amino acid sequence and in glycosylation patterns. Here we report the X-ray crystal structure of PilA from AB5075, a recently characterized, highly virulent isolate, at 1.9 Å resolution and compare it to homologues from A. baumannii strains ACICU and BIDMC57, which are C-terminally glycosylated. These structural comparisons revealed that PilAAB5075 exhibits a distinctly electronegative surface chemistry. To understand the functional consequences of this change in surface electrostatics, we complemented a ΔpilA knockout strain with divergent pilA genes from ACICU, BIDMC57, and AB5075. The resulting transgenic strains showed differential twitching motility and biofilm formation while maintaining the ability to adhere to epithelial cells. PilAAB5075 and PilAACICU, although structurally similar, promote different characteristics, favoring twitching motility and biofilm formation, respectively. These results support a model in which differences in pilus electrostatics affect the equilibrium of microcolony formation, which in turn alters the balance between motility and biofilm formation in Acinetobacter.
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Affiliation(s)
- Leslie A Ronish
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Erik Lillehoj
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - James K Fields
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Eric J Sundberg
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland 21201; Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201; Departments of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Kurt H Piepenbrink
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Departments of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, Nebraska 68588.
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39
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Susarrey-Arce A, Hernández-Sánchez JF, Marcello M, Diaz-Fernandez Y, Oknianska A, Sorzabal-Bellido I, Tiggelaar R, Lohse D, Gardeniers H, Snoeijer J, Marin A, Raval R. Bacterial Footprints in Elastic Pillared Microstructures. ACS APPLIED BIO MATERIALS 2018; 1:1294-1300. [DOI: 10.1021/acsabm.8b00176] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Arturo Susarrey-Arce
- Open Innovation Hub for Antimicrobial Surfaces at the Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
| | - José Federico Hernández-Sánchez
- Division of Physical Sciences and Engineering and Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Marco Marcello
- Institute of Integrative Biology, University of Liverpool, Biosciences Building, Liverpool L69 7ZB, United Kingdom
| | - Yuri Diaz-Fernandez
- Open Innovation Hub for Antimicrobial Surfaces at the Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
| | - Alina Oknianska
- School of Health Sciences, Liverpool Hope University, Hope Park, Liverpool L16 9JD, United Kingdom
| | - Ioritz Sorzabal-Bellido
- Open Innovation Hub for Antimicrobial Surfaces at the Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
| | - Roald Tiggelaar
- NanoLab Cleanroom, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, Enschede 7500AE, The Netherlands
| | - Detlef Lohse
- Physics of Fluids Group, MESA+ Institute for Nanotechnology, J.M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, Enschede 7500AE, The Netherlands
| | - Han Gardeniers
- Mesoscale Chemical Systems, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, Enschede 7500AE, The Netherlands
| | - Jacco Snoeijer
- Physics of Fluids Group, MESA+ Institute for Nanotechnology, J.M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, Enschede 7500AE, The Netherlands
| | - Alvaro Marin
- Physics of Fluids Group, MESA+ Institute for Nanotechnology, J.M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, Enschede 7500AE, The Netherlands
| | - Rasmita Raval
- Open Innovation Hub for Antimicrobial Surfaces at the Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
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Surface Display of Small Affinity Proteins on Synechocystis sp. Strain PCC 6803 Mediated by Fusion to the Major Type IV Pilin PilA1. J Bacteriol 2018; 200:JB.00270-18. [PMID: 29844032 DOI: 10.1128/jb.00270-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 05/22/2018] [Indexed: 11/20/2022] Open
Abstract
Functional surface display of small affinity proteins, namely, affibodies (6.5 kDa), was evaluated for the model cyanobacterium Synechocystis sp. strain PCC 6803 through anchoring to native surface structures. These structures included confirmed or putative subunits of the type IV pili, the S-layer protein, and the heterologous Escherichia coli autotransporter antigen 43 system. The most stable display system was determined to be through C-terminal fusion to PilA1, the major type IV pilus subunit in Synechocystis, in a strain unable to retract these pili (ΔpilT1). Type IV pilus synthesis was upheld, albeit reduced, when fusion proteins were incorporated. However, pilus-mediated functions, such as motility and transformational competency, were negatively affected. Display of affibodies on Synechocystis and the complementary anti-idiotypic affibodies on E. coli or Staphylococcus carnosus was able to mediate interspecies cell-cell binding by affibody complex formation. The same strategy, however, was not able to drive cell-cell binding and aggregation of Synechocystis-only mixtures. Successful affibody tagging of the putative minor pilin PilA4 showed that it locates to the type IV pili in Synechocystis and that its extracellular availability depends on PilA1. In addition, affibody tagging of the S-layer protein indicated that the domains responsible for the anchoring and secretion of this protein are located at the N and C termini, respectively. This study can serve as a basis for future surface display of proteins on Synechocystis for biotechnological applications.IMPORTANCE Cyanobacteria are gaining interest for their potential as autotrophic cell factories. Development of efficient surface display strategies could improve their suitability for large-scale applications by providing options for designed microbial consortia, cell immobilization, and biomass harvesting. Here, surface display of small affinity proteins was realized by fusing them to the major subunit of the native type IV pili in Synechocystis sp. strain PCC 6803. The display of complementary affinity proteins allowed specific cell-cell binding between Synechocystis and Escherichia coli or Staphylococcus carnosus Additionally, successful tagging of the putative pilin PilA4 helped determine its localization to the type IV pili. Analogous tagging of the S-layer protein shed light on the regions involved in its secretion and surface anchoring.
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Interplay of a secreted protein with type IVb pilus for efficient enterotoxigenic Escherichia coli colonization. Proc Natl Acad Sci U S A 2018; 115:7422-7427. [PMID: 29941571 PMCID: PMC6048534 DOI: 10.1073/pnas.1805671115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To avoid the mucosal barrier and attach to the intestinal epithelium, enteric pathogens have evolved a unique proteinaceous fiber called type IVb pilus (T4bP). Despite its importance for bacterial pathogenesis, little is known about the adhesion mechanisms of T4bP, especially regarding the role of the minor pilin subunit located at its tip. Here, we show that the type IVb minor pilin CofB of CFA/III from enterotoxigenic Escherichia coli (ETEC) plays a role not only in T4bP assembly by forming a trimeric initiator complex, but also in bacterial adhesion by anchoring a secreted protein, CofJ, at the trimerization interface of H-type lectin domain. These findings expand our knowledge of T4P biology and provide important insights for developing therapeutics against ETEC infection. Initial attachment and subsequent colonization of the intestinal epithelium comprise critical events allowing enteric pathogens to survive and express their pathogenesis. In enterotoxigenic Escherichia coli (ETEC), these are mediated by a long proteinaceous fiber termed type IVb pilus (T4bP). We have reported that the colonization factor antigen/III (CFA/III), an operon-encoded T4bP of ETEC, possesses a minor pilin, CofB, that carries an H-type lectin domain at its tip. Although CofB is critical for pilus assembly by forming a trimeric initiator complex, its importance for bacterial attachment remains undefined. Here, we show that T4bP is not sufficient for bacterial attachment, which also requires a secreted protein CofJ, encoded within the same CFA/III operon. The crystal structure of CofB complexed with a peptide encompassing the binding region of CofJ showed that CofJ interacts with CofB by anchoring its flexible N-terminal extension to be embedded deeply into the expected carbohydrate recognition site of the CofB H-type lectin domain. By combining this structure and physicochemical data in solution, we built a plausible model of the CofJ–CFA/III pilus complex, which suggested that CofJ acts as a molecular bridge by binding both T4bP and the host cell membrane. The Fab fragments of a polyclonal antibody against CofJ significantly inhibited bacterial attachment by preventing the adherence of secreted CofJ proteins. These findings signify the interplay between T4bP and a secreted protein for attaching to and colonizing the host cell surface, potentially constituting a therapeutic target against ETEC infection.
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Ellison CK, Dalia TN, Vidal Ceballos A, Wang JCY, Biais N, Brun YV, Dalia AB. Retraction of DNA-bound type IV competence pili initiates DNA uptake during natural transformation in Vibrio cholerae. Nat Microbiol 2018; 3:773-780. [PMID: 29891864 PMCID: PMC6582970 DOI: 10.1038/s41564-018-0174-y] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 05/10/2018] [Indexed: 11/09/2022]
Affiliation(s)
| | - Triana N Dalia
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Alfredo Vidal Ceballos
- Biology Department, CUNY Brooklyn College, Brooklyn, NY, USA.,Graduate Center of CUNY, New York, NY, USA
| | | | - Nicolas Biais
- Biology Department, CUNY Brooklyn College, Brooklyn, NY, USA.,Graduate Center of CUNY, New York, NY, USA
| | - Yves V Brun
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Ankur B Dalia
- Department of Biology, Indiana University, Bloomington, IN, USA.
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Elosegui-Artola A, Trepat X, Roca-Cusachs P. Control of Mechanotransduction by Molecular Clutch Dynamics. Trends Cell Biol 2018; 28:356-367. [PMID: 29496292 DOI: 10.1016/j.tcb.2018.01.008] [Citation(s) in RCA: 171] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/24/2018] [Accepted: 01/30/2018] [Indexed: 02/09/2023]
Abstract
The linkage of cells to their microenvironment is mediated by a series of bonds that dynamically engage and disengage, in what has been conceptualized as the molecular clutch model. Whereas this model has long been employed to describe actin cytoskeleton and cell migration dynamics, it has recently been proposed to also explain mechanotransduction (i.e., the process by which cells convert mechanical signals from their environment into biochemical signals). Here we review the current understanding on how cell dynamics and mechanotransduction are driven by molecular clutch dynamics and its master regulator, the force loading rate. Throughout this Review, we place a specific emphasis on the quantitative prediction of cell response enabled by combined experimental and theoretical approaches.
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Affiliation(s)
- Alberto Elosegui-Artola
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain.
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain; University of Barcelona, 08028 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain; Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, 28029 Madrid, Spain
| | - Pere Roca-Cusachs
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain; University of Barcelona, 08028 Barcelona, Spain.
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Houot L, Navarro R, Nouailler M, Duché D, Guerlesquin F, Lloubes R. Electrostatic interactions between the CTX phage minor coat protein and the bacterial host receptor TolA drive the pathogenic conversion of Vibrio cholerae. J Biol Chem 2017. [PMID: 28642371 DOI: 10.1074/jbc.m117.786061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Vibrio cholerae is a natural inhabitant of aquatic environments and converts to a pathogen upon infection by a filamentous phage, CTXΦ, that transmits the cholera toxin-encoding genes. This toxigenic conversion of V. cholerae has evident implication in both genome plasticity and epidemic risk, but the early stages of the infection have not been thoroughly studied. CTXΦ transit across the bacterial periplasm requires binding between the minor coat protein named pIII and a bacterial inner-membrane receptor, TolA, which is part of the conserved Tol-Pal molecular motor. To gain insight into the TolA-pIII complex, we developed a bacterial two-hybrid approach, named Oxi-BTH, suited for studying the interactions between disulfide bond-folded proteins in the bacterial cytoplasm of an Escherichia coli reporter strain. We found that two of the four disulfide bonds of pIII are required for its interaction with TolA. By combining Oxi-BTH assays, NMR, and genetic studies, we also demonstrate that two intermolecular salt bridges between TolA and pIII provide the driving forces of the complex interaction. Moreover, we show that TolA residue Arg-325 involved in one of the two salt bridges is critical for proper functioning of the Tol-Pal system. Our results imply that to prevent host evasion, CTXΦ uses an infection strategy that targets a highly conserved protein of Gram-negative bacteria essential for the fitness of V. cholerae in its natural environment.
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Affiliation(s)
- Laetitia Houot
- From the Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Romain Navarro
- From the Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Matthieu Nouailler
- From the Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Denis Duché
- From the Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Françoise Guerlesquin
- From the Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Roland Lloubes
- From the Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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