1
|
Leser T, Baker A. Molecular Mechanisms of Lacticaseibacillus rhamnosus, LGG ® Probiotic Function. Microorganisms 2024; 12:794. [PMID: 38674738 PMCID: PMC11051730 DOI: 10.3390/microorganisms12040794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/10/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
To advance probiotic research, a comprehensive understanding of bacterial interactions with human physiology at the molecular and cellular levels is fundamental. Lacticaseibacillus rhamnosus LGG® is a bacterial strain that has long been recognized for its beneficial effects on human health. Probiotic effector molecules derived from LGG®, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes have been identified. In vitro and animal studies have revealed that specific LGG® effector molecules stimulate epithelial cell survival, preserve intestinal barrier integrity, reduce oxidative stress, mitigate excessive mucosal inflammation, enhance IgA secretion, and provide long-term protection through epigenetic imprinting. Pili on the cell surface of LGG® promote adhesion to the intestinal mucosa and ensure close contact to host cells. Extracellular vesicles produced by LGG® recapitulate many of these effects through their cargo of effector molecules. Collectively, the effector molecules of LGG® exert a significant influence on both the gut mucosa and immune system, which promotes intestinal homeostasis and immune tolerance.
Collapse
Affiliation(s)
- Thomas Leser
- Future Labs, Human Health Biosolutions, Novonesis, Kogle Alle 6, 2970 Hoersholm, Denmark;
| | | |
Collapse
|
2
|
Bessen DE, Beall BW, Hayes A, Huang W, DiChiara JM, Velusamy S, Tettelin H, Jolley KA, Fallon JT, Chochua S, Alobaidallah MSA, Higgs C, Barnett TC, Steemson JT, Proft T, Davies MR. Recombinational exchange of M-fibril and T-pilus genes generates extensive cell surface diversity in the global group A Streptococcus population. mBio 2024:e0069324. [PMID: 38587426 DOI: 10.1128/mbio.00693-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 03/18/2024] [Indexed: 04/09/2024] Open
Abstract
Among genes present in all group A streptococci (GAS), those encoding M-fibril and T-pilus proteins display the highest levels of sequence diversity, giving rise to the two primary serological typing schemes historically used to define strain. A new genotyping scheme for the pilin adhesin and backbone genes is developed and, when combined with emm typing, provides an account of the global GAS strain population. Cluster analysis based on nucleotide sequence similarity assigns most T-serotypes to discrete pilin backbone sequence clusters, yet the established T-types correspond to only half the clusters. The major pilin adhesin and backbone sequence clusters yield 98 unique combinations, defined as "pilin types." Numerous horizontal transfer events that involve pilin or emm genes generate extensive antigenic and functional diversity on the bacterial cell surface and lead to the emergence of new strains. Inferred pilin genotypes applied to a meta-analysis of global population-based collections of pharyngitis and impetigo isolates reveal highly significant associations between pilin genotypes and GAS infection at distinct ecological niches, consistent with a role for pilin gene products in adaptive evolution. Integration of emm and pilin typing into open-access online tools (pubmlst.org) ensures broad utility for end-users wanting to determine the architecture of M-fibril and T-pilus genes from genome assemblies.IMPORTANCEPrecision in defining the variant forms of infectious agents is critical to understanding their population biology and the epidemiology of associated diseases. Group A Streptococcus (GAS) is a global pathogen that causes a wide range of diseases and displays a highly diverse cell surface due to the antigenic heterogeneity of M-fibril and T-pilus proteins which also act as virulence factors of varied functions. emm genotyping is well-established and highly utilized, but there is no counterpart for pilin genes. A global GAS collection provides the basis for a comprehensive pilin typing scheme, and online tools for determining emm and pilin genotypes are developed. Application of these tools reveals the expansion of structural-functional diversity among GAS via horizontal gene transfer, as evidenced by unique combinations of surface protein genes. Pilin and emm genotype correlations with superficial throat vs skin infection provide new insights on the molecular determinants underlying key ecological and epidemiological trends.
Collapse
Affiliation(s)
- Debra E Bessen
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Bernard W Beall
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA
- Eagle Global Scientific, LLC, Atlanta, Georgia, USA
| | - Andrew Hayes
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Weihua Huang
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
- Department of Pathology, Brody School of Medicine, Eastern Carolina University, Greenville, North Carolina, USA
| | - Jeanne M DiChiara
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Srinivasan Velusamy
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA
| | - Hervé Tettelin
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Keith A Jolley
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - John T Fallon
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
- Department of Pathology, Brody School of Medicine, Eastern Carolina University, Greenville, North Carolina, USA
| | - Sopio Chochua
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA
| | - Mosaed S A Alobaidallah
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Charlie Higgs
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Timothy C Barnett
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Nedlands, Australia
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, Australia
| | - John T Steemson
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Thomas Proft
- School of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | | |
Collapse
|
3
|
Guberman-Pfeffer MJ. To be or not to be a cytochrome: electrical characterizations are inconsistent with Geobacter cytochrome 'nanowires'. Front Microbiol 2024; 15:1397124. [PMID: 38633696 PMCID: PMC11021709 DOI: 10.3389/fmicb.2024.1397124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024] Open
Abstract
Geobacter sulfurreducens profoundly shapes Earth's biogeochemistry by discharging respiratory electrons to minerals and other microbes through filaments of a two-decades-long debated identity. Cryogenic electron microscopy has revealed filaments of redox-active cytochromes, but the same filaments have exhibited hallmarks of organic metal-like conductivity under cytochrome denaturing/inhibiting conditions. Prior structure-based calculations and kinetic analyses on multi-heme proteins are synthesized herein to propose that a minimum of ~7 cytochrome 'nanowires' can carry the respiratory flux of a Geobacter cell, which is known to express somewhat more (≥20) filaments to increase the likelihood of productive contacts. By contrast, prior electrical and spectroscopic structural characterizations are argued to be physiologically irrelevant or physically implausible for the known cytochrome filaments because of experimental artifacts and sample impurities. This perspective clarifies our mechanistic understanding of physiological metal-microbe interactions and advances synthetic biology efforts to optimize those interactions for bioremediation and energy or chemical production.
Collapse
|
4
|
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 DOI: 10.1128/mmbr.00125-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [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.
Collapse
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
| |
Collapse
|
5
|
Maddirala AR, Tamadonfar K, Pinkner JS, Sanick D, Hultgren SJ, Janetka JW. Discovery of Orally Bioavailable FmlH Lectin Antagonists as Treatment for Urinary Tract Infections. J Med Chem 2024; 67:3668-3678. [PMID: 38308631 PMCID: PMC10994195 DOI: 10.1021/acs.jmedchem.3c02128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2024]
Abstract
FmlH, a bacterial adhesin of uropathogenic Escherichia coli (UPEC), has been shown to provide a fitness advantage in colonizing the bladder during chronic urinary tract infections (UTIs). Previously reported ortho-biphenyl glycosides based on βGal and βGalNAc have excellent binding affinity to FmlH and potently block binding to its natural carbohydrate receptor, but they lack oral bioavailability. In this paper, we outline studies where we have optimized compounds for improved pharmacokinetics, leading to the discovery of novel analogues with good oral bioavailability. We synthesized galactosides with the anomeric O-linker replaced with more stable S- and C-linked linkers. We also investigated modifications to the GalNAc sugar and modifications to the biphenyl aglycone. We identified GalNAc 69 with an IC50 of 0.19 μM against FmlH and 53% oral bioavailability in mice. We also obtained a FimlH-bound X-ray structure of lead compound 69 (AM4085) which has potential as a new antivirulence therapeutic for UTIs.
Collapse
Affiliation(s)
- Amarendar Reddy Maddirala
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kevin Tamadonfar
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jerome S. Pinkner
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Denise Sanick
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Scott J. Hultgren
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women’s Infectious Disease Research, Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - James W. Janetka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Center for Women’s Infectious Disease Research, Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| |
Collapse
|
6
|
Whiteley LE, Whiteley M. Characterization of a new Pseudomonas aeruginosa Queuovirinae bacteriophage. Microbiol Spectr 2024; 12:e0371923. [PMID: 38345389 PMCID: PMC10913419 DOI: 10.1128/spectrum.03719-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 01/17/2024] [Indexed: 03/06/2024] Open
Abstract
The ESKAPEE pathogen Pseudomonas aeruginosa is a common cause of chronic wound and cystic fibrosis lung infections, as well as acute burn and nosocomial infections. Many of these infections are recalcitrant to conventional antibiotic therapies due to both traditional antibiotic resistance mechanisms and antimicrobial tolerance. Recent successes with bacteriophage (phage) therapy to treat chronic human P. aeruginosa infections have led to a renewed interest in isolating and characterizing new P. aeruginosa phages. Here, we isolated and characterized a new lytic phage (termed PIP, pili-infecting phage) capable of infecting P. aeruginosa PA14. PIP is a tailed phage with an icosahedral head and flexible tail containing a genome that is 57,462 bp in length. Phylogenetic analysis reveals that PIP belongs to the subfamily Queuovirinae and genus Nipunavirus but is highly divergent in gene content from known Nipunaviruses. By isolating and characterizing a P. aeruginosa strain that spontaneously evolved resistance to PIP, we show that the receptor for PIP is Type IV pili. In summary, we isolated a new P. aeruginosa phage species with a unique genome, thus increasing the diversity of phages known to infect this important human pathogen.IMPORTANCEThe opportunistic pathogen Pseudomonas aeruginosa causes both acute and chronic human infections. These infections are notoriously difficult to treat due to both antibiotic resistance and antibiotic tolerance. The increasing frequency of antibiotic failure in P. aeruginosa infections has led scientists to explore other treatment options, including bacteriophage (phage) therapy. To this end, there has been a significant effort to identify new Pseudomonas phages. Here, we isolated and characterized a bacteriophage (termed PIP, pili-infecting phage) that infects P. aeruginosa PA14. Examination of the PIP genome revealed that this phage represents a new species in the subclass Queuovirinae. The isolation and characterization of spontaneous PA14 mutants that are resistant to PIP infection revealed Type IV pili as the PIP receptor. Ultimately, this study characterizes a new species of Pseudomonas phage, thus enhancing the known diversity of phages that infect this important pathogen.
Collapse
Affiliation(s)
- Lauren E. Whiteley
- School of Biological Sciences, Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children’s Cystic Fibrosis Center, Atlanta, Georgia, USA
| | - Marvin Whiteley
- School of Biological Sciences, Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children’s Cystic Fibrosis Center, Atlanta, Georgia, USA
| |
Collapse
|
7
|
Geslewitz WE, Cardenas A, Zhou X, Zhang Y, Criss AK, Seifert HS. Development and implementation of a Type I-C CRISPR-based programmable repression system for Neisseria gonorrhoeae. mBio 2024; 15:e0302523. [PMID: 38126782 PMCID: PMC10865793 DOI: 10.1128/mbio.03025-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) are prokaryotic adaptive immune systems regularly utilized as DNA-editing tools. While Neisseria gonorrhoeae does not have an endogenous CRISPR, the commensal species Neisseria lactamica encodes a functional Type I-C CRISPR-Cas system. We have established an isopropyl β-d-1-thiogalactopyranoside added (IPTG)-inducible, CRISPR interference (CRISPRi) platform based on the N. lactamica Type I-C CRISPR missing the Cas3 nuclease to allow locus-specific transcriptional repression. As proof of principle, we targeted a non-phase-variable version of the opaD gene. We show that CRISPRi can downregulate opaD gene and protein expression, resulting in bacterial inability to stimulate neutrophil oxidative responses and to bind to an N-terminal fragment of CEACAM1. Importantly, we used CRISPRi to effectively knockdown all the transcripts of all 11 opa genes using a five-spacer CRISPR array, allowing control of the entire phase-variable opa family in strain FA1090. We also report that repression is reversible following IPTG removal. Finally, we showed that the Type I-C CRISPRi system can conditionally reduce the expression of two essential genes. This CRISPRi system will allow the interrogation of every Gc gene, essential and non-essential, to study physiology and pathogenesis and aid in antimicrobial development.IMPORTANCEClustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems have proven instrumental in genetically manipulating many eukaryotic and prokaryotic organisms. Despite its usefulness, a CRISPR system had yet to be developed for use in Neisseria gonorrhoeae (Gc), a bacterium that is the main etiological agent of gonorrhea infection. Here, we developed a programmable and IPTG-inducible Type I-C CRISPR interference (CRISPRi) system derived from the commensal species Neisseria lactamica as a gene repression system in Gc. As opposed to generating genetic knockouts, the Type I-C CRISPRi system allows us to block transcription of specific genes without generating deletions in the DNA. We explored the properties of this system and found that a minimal spacer array is sufficient for gene repression while also facilitating efficient spacer reprogramming. Importantly, we also show that we can use CRISPRi to knockdown genes that are essential to Gc that cannot normally be knocked out under laboratory settings. Gc encodes ~800 essential genes, many of which have no predicted function. We predict that this Type I-C CRISPRi system can be used to help categorize gene functions and perhaps contribute to the development of novel therapeutics for gonorrhea.
Collapse
Affiliation(s)
- Wendy E. Geslewitz
- Department of Microbiology and Immunology, Northwestern University, Chicago, Illinois, USA
| | - Amaris Cardenas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Xufei Zhou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Yan Zhang
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Alison K. Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - H Steven Seifert
- Department of Microbiology and Immunology, Northwestern University, Chicago, Illinois, USA
| |
Collapse
|
8
|
Takahashi R, J-Khemlani AH, Loh JMS, Radcliff FJ, Proft T, Tsai CJY. Different Group A Streptococcus pili lead to varying proinflammatory cytokine responses and virulence. Immunol Cell Biol 2024; 102:21-33. [PMID: 37795567 DOI: 10.1111/imcb.12692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 10/06/2023]
Abstract
The human pathogen Streptococcus pyogenes, or Group A Streptococcus (GAS), is associated with a variety of diseases ranging from mild skin and soft tissue infections to invasive diseases and immune sequelae such as rheumatic heart disease. We have recently reported that one of the virulence factors of this pathogen, the pilus, has inflammatory properties and strongly stimulates the innate immune system. Here we used a range of nonpathogenic Lactococcus lactis gain-of-function mutants, each expressing one of the major pilus types of GAS, to compare the immune responses generated by various types of fully assembled pili. In vitro assays indicated variability in the inflammatory response induced by different pili, with the fibronectin-binding, collagen-binding, T antigen (FCT)-1-type pilus from GAS serotype M6/T6 inducing significantly stronger cytokine secretion than other pili. Furthermore, we established that the same trend of pili-mediated immune response could be modeled in Galleria mellonella larvae, which possess a similar innate immune system to vertebrates. Counterintuitively, across the panel of pili types examined in this study, we observed a negative correlation between the intensity of the immune response demonstrated in our experiments and the disease severity observed clinically in the GAS strains associated with each pilus type. This observation suggests that pili-mediated inflammation is more likely to promote bacterial clearance instead of causing disruptive damages that intensify pathogenesis. This also indicates that pili may not be the main contributor to the inflammatory symptoms seen in GAS diseases. Rather, the immune-potentiating properties of the pilus components could potentially be exploited as a vaccine adjuvant.
Collapse
Affiliation(s)
- Risa Takahashi
- Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, Auckland, New Zealand
| | - Adrina Hema J-Khemlani
- Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, Auckland, New Zealand
| | - Jacelyn Mei San Loh
- Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
| | - Fiona Jane Radcliff
- Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
| | - Thomas Proft
- Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
| | - Catherine Jia-Yun Tsai
- Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
| |
Collapse
|
9
|
Zuke JD, Erickson R, Hummels KR, Burton BM. Visualizing dynamic competence pili and DNA capture throughout the long axis of Bacillus subtilis. J Bacteriol 2023; 205:e0015623. [PMID: 37695859 PMCID: PMC10521363 DOI: 10.1128/jb.00156-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 06/05/2023] [Indexed: 09/13/2023] Open
Abstract
The first step in the process of bacterial natural transformation is DNA capture. Although long hypothesized based on genetics and functional experiments, the pilus structure responsible for initial DNA binding had not yet been visualized for Bacillus subtilis. Here, we visualize functional competence pili in Bacillus subtilis using fluorophore-conjugated maleimide labeling in conjunction with epifluorescence microscopy. In strains that produce pilin monomers within tenfold of wild-type levels, the median length of detectable pili is 300 nm. These pili are retractile and associate with DNA. The analysis of pilus distribution at the cell surface reveals that they are predominantly located along the long axis of the cell. The distribution is consistent with localization of proteins associated with subsequent transformation steps, DNA binding, and DNA translocation in the cytosol. These data suggest a distributed model for B. subtilis transformation machinery, in which initial steps of DNA capture occur throughout the long axis of the cell and subsequent steps may also occur away from the cell poles. IMPORTANCE This work provides novel visual evidence for DNA translocation across the cell wall during Bacillus subtilis natural competence, an essential step in the natural transformation process. Our data demonstrate the existence of natural competence-associated retractile pili that can bind exogenous DNA. Furthermore, we show that pilus biogenesis occurs throughout the cell long axis. These data strongly support DNA translocation occurring all along the lateral cell wall during natural competence, wherein pili are produced, bind to free DNA in the extracellular space, and finally retract to pull the bound DNA through the gap in the cell wall created during pilus biogenesis.
Collapse
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
| | - Rachel Erickson
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Katherine R. Hummels
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA, USA
| | - Briana M. Burton
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| |
Collapse
|
10
|
Dubnau D. Watching DNA uptake: B. subtilis joins the crowd. J Bacteriol 2023; 205:e0018523. [PMID: 37695855 PMCID: PMC10521350 DOI: 10.1128/jb.00185-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023] Open
Affiliation(s)
- D. Dubnau
- Public Health Research Institute, Rutgers University, Newark, New Jersey, USA
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| |
Collapse
|
11
|
Zuke JD, Erickson R, Hummels KR, Burton BM. Visualizing dynamic competence pili and DNA capture throughout the long axis of Bacillus subtilis. bioRxiv 2023:2023.05.26.542325. [PMID: 37292776 PMCID: PMC10246001 DOI: 10.1101/2023.05.26.542325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The first step in the process of bacterial natural transformation is DNA capture. Although long-hypothesized based on genetics and functional experiments, the pilus structure responsible for initial DNA-binding had not yet been visualized for Bacillus subtilis. Here, we visualize functional competence pili in Bacillus subtilis using fluorophore-conjugated maleimide labeling in conjunction with epifluorescence microscopy. In strains that produce pilin monomers within ten-fold of wild type levels, the median length of detectable pili is 300nm. These pili are retractile and associate with DNA. Analysis of pilus distribution at the cell surface reveals that they are predominantly located along the long axis of the cell. The distribution is consistent with localization of proteins associated with subsequent transformation steps, DNA-binding and DNA translocation in the cytosol. These data suggest a distributed model for B. subtilis transformation machinery, in which initial steps of DNA capture occur throughout the long axis of the cell and subsequent steps may also occur away from the cell poles.
Collapse
Affiliation(s)
- Jason D. Zuke
- Department of Bacteriology, University of Wisconsin - Madison
- Microbiology Doctoral Training Program, University of Wisconsin - Madison
| | - Rachel Erickson
- Department of Bacteriology, University of Wisconsin - Madison
| | - Katherine R. Hummels
- Current address: Department of Microbiology and Immunology, Harvard Medical School
| | | |
Collapse
|
12
|
Jonsmoen UL, Malyshev D, Berg R, Dahlberg T, Aspholm ME, Andersson M. Endospore pili - flexible, stiff and sticky nanofibers. Biophys J 2023:S0006-3495(23)00336-3. [PMID: 37218131 PMCID: PMC10397575 DOI: 10.1016/j.bpj.2023.05.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 03/29/2023] [Accepted: 05/18/2023] [Indexed: 05/24/2023] Open
Abstract
Species belonging to the Bacillus cereus group form endospores (spores) whose surface is decorated with micrometers-long and nanometers-wide endospore appendages (Enas). The Enas have recently been shown to represent a completely novel class of Gram-positive pili. They exhibit remarkable structural properties making them extremely resilient to proteolytic digestion and solubilization. However, little is known about their functional and biophysical properties. In this work, we apply optical tweezers to manipulate and assess how wild type and Ena-depleted mutant spores immobilize on a glass surface. Further, we utilize optical tweezers to extend S-Ena fibers to measure their flexibility and tensile stiffness. Finally, by oscillating single spores, we examine how the exosporium and Enas affect spores' hydrodynamic properties. Our results show that S-Enas (μm long pili) are not as effective as L-Enas in immobilizing spores to glass surfaces but are involved in forming spore to spore connections, holding the spores together in a gel-like state. The measurements also show that S-Enas are flexible but tensile stiff fibers, which support structural data suggesting that the quaternary structure is composed of subunits arranged in a complex to produce a bendable fiber (helical turns can tilt against each other) with limited axial fiber extensibility. Lastly, the results show that the hydrodynamic drag is 1.5-times higher for wild type spores expressing S- and L-Enas compared to mutant spores expressing only L-Enas or "bald spores" lacking Ena, and 2-times higher compared to spores of the exosporium deficient strain. This study unveils novel findings on the biophysics of S- and L-Enas, their role in spore aggregation, binding of spores to glass, and their mechanical behavior upon exposure to drag forces.
Collapse
Affiliation(s)
- Unni Lise Jonsmoen
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432 Ås, Norway
| | - Dmitry Malyshev
- Department of Physics, Umeå University, 901 87, Umeå, Sweden
| | - Rasmus Berg
- Department of Physics, Umeå University, 901 87, Umeå, Sweden
| | - Tobias Dahlberg
- Department of Physics, Umeå University, 901 87, Umeå, Sweden
| | - Marina E Aspholm
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432 Ås, Norway.
| | - Magnus Andersson
- Department of Physics, Umeå University, 901 87, Umeå, Sweden; Umeå Centre for Microbial Research (UCMR), Umeå, Sweden.
| |
Collapse
|
13
|
Kubota S, Nakata M, Hirose Y, Yamaguchi M, Kreikemeyer B, Uzawa N, Sumitomo T, Kawabata S. Involvement of ribonuclease Y in pilus production by M49 Streptococcus pyogenes strain via modulation of messenger RNA level of transcriptional regulator. Microbiol Immunol 2023. [PMID: 37138376 DOI: 10.1111/1348-0421.13069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 05/05/2023]
Abstract
Streptococcus pyogenes displays a wide variety of pili, which is largely dependent on serotype. A distinct subset of S. pyogenes strains that possess the Nra transcriptional regulator demonstrates thermoregulated pilus production. Findings obtained in the present study of an Nra-positive serotype M49 strain revealed involvement of conserved virulence factor A (CvfA), also referred to as ribonuclease Y (RNase Y), in virulence factor expression and pilus production, while a cvfA deletion strain showed reduced pilus production and adherence to human keratinocytes as compared with wild-type and revertant strains. Furthermore, transcript levels of pilus subunits and srtC2 genes were decreased by cvfA deletion, which was remarkable at 25°C. Likewise, both messenger RNA (mRNA) and protein levels of Nra were remarkably decreased by cvfA deletion. Whether the expression of other pilus-related regulators, including fasX and CovR, was subject to thermoregulation was also examined. While the mRNA level of fasX, which inhibits cpa and fctA translation, was decreased by cvfA deletion at both 37°C and 25°C, CovR mRNA and protein levels, as well as its phosphorylation level were not significantly changed, suggesting that neither fasX nor CovR is necessarily involved in thermosensitive pilus production. Phenotypic analysis of the mutant strains revealed that culture temperature and cvfA deletion had varied effects on streptolysin S and SpeB activities. Furthermore, bactericidal assay data showed that cvfA deletion decreased the rate of survival in human blood. Together, the present findings indicate that CvfA is involved in regulation of pilus production and virulence-related phenotypes of the serotype M49 strain of S. pyogenes.
Collapse
Affiliation(s)
- Seiko Kubota
- Department of Microbiology, Osaka University Graduate School of Dentistry, Osaka, Japan
- Department of Oral and Maxillofacial Surgery II, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Masanobu Nakata
- Department of Microbiology, Osaka University Graduate School of Dentistry, Osaka, Japan
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yujiro Hirose
- Department of Microbiology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Masaya Yamaguchi
- Department of Microbiology, Osaka University Graduate School of Dentistry, Osaka, Japan
- Bioinformatics Research Unit, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Bernd Kreikemeyer
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Narikazu Uzawa
- Department of Oral and Maxillofacial Surgery II, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Tomoko Sumitomo
- Department of Microbiology, Osaka University Graduate School of Dentistry, Osaka, Japan
- Department of Oral Microbiology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Shigetada Kawabata
- Department of Microbiology, Osaka University Graduate School of Dentistry, Osaka, Japan
| |
Collapse
|
14
|
Tamai E, Yamada M, Ishida T, Arimura N, Matsunami R, Sekiya H, Kamitori S. Structural and biochemical characterization of Clostridium perfringens pili protein B collagen-binding domains. FEBS Lett 2023; 597:1345-1354. [PMID: 37071018 DOI: 10.1002/1873-3468.14626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/17/2023] [Accepted: 04/04/2023] [Indexed: 04/19/2023]
Abstract
Sortase-mediated pili are flexible rod proteins composed of major and minor/tip pilins, playing important roles in the initial adhesion of bacterial cells to host tissues. The pilus shaft is formed by covalent polymerization of major pilins, and the minor/tip pilin is covalently attached to the tip of the shaft involved in adhesion to the host cell. The Gram-positive bacterium Clostridium perfringens has a major pilin, and a minor/tip pilin (CppB) with the collagen-binding motif. Here, we report X-ray structures of CppB collagen-binding domains, collagen-binding assays, and mutagenesis analysis, demonstrating that CppB collagen-binding domains adopt an L-shaped structure in open form, and that a small β-sheet unique to CppB provides a scaffold for a favorable binding site for collagen peptide.
Collapse
Affiliation(s)
- Eiji Tamai
- Department of Infectious Disease, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime, 790-8578, Japan
| | - Mitsugu Yamada
- Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba, Ibaraki, 305-8505, Japan
| | - Takuya Ishida
- Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba, Ibaraki, 305-8505, Japan
| | - Nayu Arimura
- Department of Infectious Disease, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime, 790-8578, Japan
| | - Risa Matsunami
- Department of Infectious Disease, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime, 790-8578, Japan
| | - Hiroshi Sekiya
- Department of Infectious Disease, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime, 790-8578, Japan
| | - Shigehiro Kamitori
- Research Facility Center for Science & Technology and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan
| |
Collapse
|
15
|
Kreiling V, Thormann KM. Polarity of c-di-GMP synthesis and degradation. Microlife 2023; 4:uqad014. [PMID: 37251513 PMCID: PMC10212136 DOI: 10.1093/femsml/uqad014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/20/2023] [Accepted: 04/04/2023] [Indexed: 05/31/2023]
Abstract
The bacterial cell pole has long been recognized as a defined compartment for enzymatic activities that are important or even vital for the cell. Polarity of diguanylate cyclases and phosphodiesterases, enzymes that synthesize and degrade the second messenger c-di-GMP, has now been demonstrated for several bacterial systems. Here we review these polar regulatory systems and show how the asymmetry of c-di-GMP production and turnover in concert with different modes of activation and deactivation creates heterogeneity in cellular c-di-GMP levels. We highlight how this heterogeneity generates a diverse set of phenotypic identities or states and how this may benefit the cell population, and we discuss reasons why the polarity of c-di-GMP signaling is probably widespread among bacteria.
Collapse
Affiliation(s)
- Vanessa Kreiling
- Justus-Liebig-Universität, Institute of Microbiology and Molecular Biology, Heinrich-Buff-Ring 26, 35392 Giessen, Germany
| | - Kai M Thormann
- Corresponding author. Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 26; D-35392 Gießen, Germany. E-mail:
| |
Collapse
|
16
|
Doran MH, Baker JL, Dahlberg T, Andersson M, Bullitt E. Three structural solutions for bacterial adhesion pilus stability and superelasticity. Structure 2023; 31:529-540.e7. [PMID: 37001523 PMCID: PMC10164138 DOI: 10.1016/j.str.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/18/2023] [Accepted: 03/06/2023] [Indexed: 04/22/2023]
Abstract
Bacterial adhesion pili are key virulence factors that mediate host-pathogen interactions in diverse epithelial environments. Deploying a multimodal approach, we probed the structural basis underpinning the biophysical properties of pili originating from enterotoxigenic (ETEC) and uropathogenic bacteria. Using cryo-electron microscopy we solved the structures of three vaccine target pili from ETEC bacteria, CFA/I, CS17, and CS20. Pairing these and previous pilus structures with force spectroscopy and steered molecular dynamics simulations, we find a strong correlation between subunit-subunit interaction energies and the force required for pilus unwinding, irrespective of genetic similarity. Pili integrate three structural solutions for stabilizing their assemblies: layer-to-layer interactions, N-terminal interactions to distant subunits, and extended loop interactions from adjacent subunits. Tuning of these structural solutions alters the biophysical properties of pili and promotes the superelastic behavior that is essential for sustained bacterial attachment.
Collapse
Affiliation(s)
- Matthew H Doran
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Joseph L Baker
- Department of Chemistry, The College of New Jersey, Ewing, NJ 08628, USA
| | | | - Magnus Andersson
- Department of Physics, Umeå University, Umeå, Sweden; Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Esther Bullitt
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA.
| |
Collapse
|
17
|
Abstract
Type 4 filaments (T4F) are a superfamily of filamentous nanomachines - virtually ubiquitous in prokaryotes and functionally versatile - of which type 4 pili (T4P) are the defining member. T4F are polymers of type 4 pilins, assembled by conserved multi-protein machineries. They have long been an important topic for research because they are key virulence factors in numerous bacterial pathogens. Our poor understanding of the molecular mechanisms of T4F assembly is a serious hindrance to the design of anti-T4F therapeutics. This review attempts to shed light on the fundamental mechanistic principles at play in T4F assembly by focusing on similarities rather than differences between several (mostly bacterial) T4F. This holistic approach, complemented by the revolutionary ability of artificial intelligence to predict protein structures, led to an intriguing mechanistic model of T4F assembly.
Collapse
Affiliation(s)
- Vladimir Pelicic
- Laboratoire de Chimie Bactérienne, UMR 7283 CNRS/Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, Marseille, France
| |
Collapse
|
18
|
Reardon-Robinson ME, Nguyen MT, Sanchez BC, Osipiuk J, Rückert C, Chang C, Chen B, Nagvekar R, Joachimiak A, Tauch A, Das A, Ton-That H. A cryptic oxidoreductase safeguards oxidative protein folding in Corynebacterium diphtheriae. Proc Natl Acad Sci U S A 2023; 120:e2208675120. [PMID: 36787356 PMCID: PMC9974433 DOI: 10.1073/pnas.2208675120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 01/17/2023] [Indexed: 02/15/2023] Open
Abstract
In many gram-positive Actinobacteria, including Actinomyces oris and Corynebacterium matruchotii, the conserved thiol-disulfide oxidoreductase MdbA that catalyzes oxidative folding of exported proteins is essential for bacterial viability by an unidentified mechanism. Intriguingly, in Corynebacterium diphtheriae, the deletion of mdbA blocks cell growth only at 37 °C but not at 30 °C, suggesting the presence of alternative oxidoreductase enzyme(s). By isolating spontaneous thermotolerant revertants of the mdbA mutant at 37 °C, we obtained genetic suppressors, all mapped to a single T-to-G mutation within the promoter region of tsdA, causing its elevated expression. Strikingly, increased expression of tsdA-via suppressor mutations or a constitutive promoter-rescues the pilus assembly and toxin production defects of this mutant, hence compensating for the loss of mdbA. Structural, genetic, and biochemical analyses demonstrated TsdA is a membrane-tethered thiol-disulfide oxidoreductase with a conserved CxxC motif that can substitute for MdbA in mediating oxidative folding of pilin and toxin substrates. Together with our observation that tsdA expression is upregulated at nonpermissive temperature (40 °C) in wild-type cells, we posit that TsdA has evolved as a compensatory thiol-disulfide oxidoreductase that safeguards oxidative protein folding in C. diphtheriae against thermal stress.
Collapse
Affiliation(s)
- Melissa E. Reardon-Robinson
- Department of Microbiology & Molecular Genetics, University of Texas McGovern Medical School, Houston, TX77030
| | - Minh Tan Nguyen
- Division of Oral and Systemic Health Sciences, School of Dentistry, University of California, Los Angeles, CA90095
| | - Belkys C. Sanchez
- Department of Microbiology & Molecular Genetics, University of Texas McGovern Medical School, Houston, TX77030
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX77030
| | - Jerzy Osipiuk
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL60637
- Structural Biology Center, Argonne National Laboratory, Lemont, IL60439
| | - Christian Rückert
- Center for Biotechnology, Bielefeld University, D-33615Bielefeld, Germany
| | - Chungyu Chang
- Division of Oral and Systemic Health Sciences, School of Dentistry, University of California, Los Angeles, CA90095
| | - Bo Chen
- Department of Microbiology & Molecular Genetics, University of Texas McGovern Medical School, Houston, TX77030
| | - Rahul Nagvekar
- Department of Microbiology & Molecular Genetics, University of Texas McGovern Medical School, Houston, TX77030
- Stanford University, Stanford, CA94305
| | - Andrzej Joachimiak
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL60637
- Structural Biology Center, Argonne National Laboratory, Lemont, IL60439
| | - Andreas Tauch
- Center for Biotechnology, Bielefeld University, D-33615Bielefeld, Germany
| | - Asis Das
- Department of Medicine, Neag Comprehensive Cancer Center, University of Connecticut Health Center, Farmington, CT06030
| | - Hung Ton-That
- Division of Oral and Systemic Health Sciences, School of Dentistry, University of California, Los Angeles, CA90095
- Molecular Biology Institute, University of California, Los Angeles, CA90095
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA90095
| |
Collapse
|
19
|
Choo PY, Wang CY, VanNieuwenhze MS, Kline KA. Spatial and temporal localization of cell wall associated pili in Enterococcus faecalis. Mol Microbiol 2023; 119:1-18. [PMID: 36420961 PMCID: PMC10107303 DOI: 10.1111/mmi.15008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
Enterococcus faecalis virulence requires cell wall-associated proteins, including the sortase-assembled endocarditis and biofilm associated pilus (Ebp), important for biofilm formation in vitro and in vivo. The current paradigm for sortase-assembled pilus biogenesis in Gram-positive bacteria is that sortases attach substrates to lipid II peptidoglycan (PG) precursors, prior to their incorporation into the growing cell wall. Contrary to prevailing dogma, by following the distribution of Ebp and PG throughout the E. faecalis cell cycle, we found that cell surface Ebp do not co-localize with newly synthesized PG. Instead, surface-exposed Ebp are localized to the older cell hemisphere and excluded from sites of new PG synthesis at the septum. Moreover, Ebp deposition on the younger hemisphere of the E. faecalis diplococcus appear as foci adjacent to the nascent septum. We propose a new model whereby sortase substrate deposition can occur on older PG rather than at sites of new cell wall synthesis. Consistent with this model, we demonstrate that sequestering lipid II to block PG synthesis via ramoplanin, does not impact new Ebp deposition at the cell surface. These data support an alternative paradigm for sortase substrate deposition in E. faecalis, in which Ebp are anchored directly onto uncrosslinked cell wall, independent of new PG synthesis.
Collapse
Affiliation(s)
- Pei Yi Choo
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Charles Y Wang
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | | | - Kimberly A Kline
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| |
Collapse
|
20
|
Giese B, Karamash M, Fromm KM. Chances and challenges of long-distance electron transfer for cellular redox reactions. FEBS Lett 2023; 597:166-173. [PMID: 36114008 DOI: 10.1002/1873-3468.14493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 01/14/2023]
Abstract
Biological redox reactions often use a set-up in which final redox partners are localized in different compartments and electron transfer (ET) among them is mediated by redox-active molecules. In enzymes, these ET processes occur over nm distances, whereas multi-protein filaments bridge μm ranges. Electrons are transported over cm ranges in cable bacteria, which are formed by thousands of cells. In this review, we describe molecular mechanisms that explain how respiration in a compartmentalized set-up ensures redox homeostasis. We highlight mechanistic studies on ET through metal-free peptides and proteins demonstrating that long-distance ET is possible because amino acids Tyr, Trp, Phe, and Met can act as relay stations. This cuts one long ET into several short reaction steps. The chances and challenges of long-distance ET for cellular redox reactions are then discussed.
Collapse
Affiliation(s)
- Bernd Giese
- Department of Chemistry, University of Fribourg, Switzerland
| | - Maksym Karamash
- Department of Chemistry, University of Fribourg, Switzerland
| | | |
Collapse
|
21
|
Nayak AR, Singh PK, Zhao J, Samsó M, Donnenberg MS. Cryo-EM Structure of the Type IV Pilus Extension ATPase from Enteropathogenic Escherichia coli. mBio 2022; 13:e0227022. [PMID: 36326250 DOI: 10.1128/mbio.02270-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type 4 pili (T4P) are retractable surface appendages found on numerous bacteria and archaea that play essential roles in various microbial functions, including host colonization by pathogens. An ATPase is required for T4P extension, but the mechanism by which chemical energy is transduced to mechanical energy for pilus extension has not been elucidated. Here, we report the cryo-electron microscopy (cryo-EM) structure of the BfpD ATPase from enteropathogenic Escherichia coli (EPEC) in the presence of either ADP or a mixture of ADP and AMP-PNP. Both structures, solved at 3 Å resolution, reveal the typical toroid shape of AAA+ ATPases and unambiguous 6-fold symmetry. This 6-fold symmetry contrasts with the 2-fold symmetry previously reported for other T4P extension ATPase structures, all of which were from thermophiles and solved by crystallography. In the presence of the nucleotide mixture, BfpD bound exclusively AMP-PNP, and this binding resulted in a modest outward expansion in comparison to the structure in the presence of ADP, suggesting a concerted model for hydrolysis. De novo molecular models reveal a partially open configuration of all subunits where the nucleotide binding site may not be optimally positioned for catalysis. ATPase functional studies reveal modest activity similar to that of other extension ATPases, while calculations indicate that this activity is insufficient to power pilus extension. Our results reveal that, despite similarities in primary sequence and tertiary structure, T4P extension ATPases exhibit divergent quaternary configurations. Our data raise new possibilities regarding the mechanism by which T4P extension ATPases power pilus formation. IMPORTANCE Type 4 pili are hairlike surface appendages on many bacteria and archaea that can be extended and retracted with tremendous force. They play a critical role in disease caused by several deadly human pathogens. Pilus extension is made possible by an enzyme that converts chemical energy to mechanical energy. Here, we describe the three-dimensional structure of such an enzyme from a human pathogen in unprecedented detail, which reveals a mechanism of action that has not been seen previously among enzymes that power type 4 pilus extension.
Collapse
|
22
|
Amro J, Black C, Jemouai Z, Rooney N, Daneault C, Zeytuni N, Ruiz M, Bui KH, Baron C. Cryo-EM structure of the Agrobacterium tumefaciens T-pilus reveals the importance of positive charges in the lumen. Structure 2022. [PMID: 36513067 DOI: 10.1016/j.str.2022.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 09/19/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022]
Abstract
Agrobacterium tumefaciens is a natural genetic engineer that transfers DNA into plants, which is the most applied process for generation of genetically modified plants. DNA transfer is mediated by a type IV secretion system in the cell envelope and extracellular T-pili. We here report the cryo-electron microscopic structures of the T-pilus at 3.2-Å resolution and of the plasmid pKM101-determined N-pilus at 3-Å resolution. Both pili contain a main pilus protein (VirB2 in A. tumefaciens, TraM in pKM101) and phospholipids arranged in a five-start helical assembly. They contain positively charged amino acids in the lumen, and the lipids are positively charged in the T-pilus (phosphatidylcholine) conferring overall positive charge. Mutagenesis of the lumen-exposed Arg91 in VirB2 results in protein destabilization and loss of pilus formation. Our results reveal that different phospholipids can be incorporated into type IV secretion pili and that the charge of the lumen may be of functional importance.
Collapse
|
23
|
Okahashi N, Nakata M, Kuwata H, Kawabata S. Oral mitis group streptococci: A silent majority in our oral cavity. Microbiol Immunol 2022; 66:539-551. [PMID: 36114681 DOI: 10.1111/1348-0421.13028] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/11/2022] [Accepted: 09/12/2022] [Indexed: 12/13/2022]
Abstract
Members of the oral mitis group streptococci including Streptococcus oralis, Streptococcus sanguinis, and Streptococcus gordonii are the most abundant inhabitants of human oral cavity and dental plaque, and have been implicated in infectious complications such as bacteremia and infective endocarditis. Oral mitis group streptococci are genetically close to Streptococcus pneumoniae; however, they do not produce cytolysin (pneumolysin), which is a key virulence factor of S. pneumoniae. Similar to S. pneumoniae, oral mitis group streptococci possess several cell surface proteins that bind to the cell surface components of host mammalian cells. S. sanguinis expresses long filamentous pili that bind to the matrix proteins of host cells. The cell wall-anchored nuclease of S. sanguinis contributes to the evasion of the neutrophil extracellular trap by digesting its web-like extracellular DNA. Oral mitis group streptococci produce glucosyltransferases, which synthesize glucan (glucose polymer) from sucrose of dietary origin. Neuraminidase (NA) is a virulent factor in oral mitis group streptococci. Influenza type A virus (IAV) relies on viral NA activity to release progeny viruses from infected cells and spread the infection, and NA-producing oral streptococci elevate the risk of IAV infection. Moreover, oral mitis group streptococci produce hydrogen peroxide (H2 O2 ) as a by-product of sugar metabolism. Although the concentrations of streptococcal H2 O2 are low (1-2 mM), they play important roles in bacterial competition in the oral cavity and evasion of phagocytosis by host macrophages and neutrophils. In this review, we intended to describe the diverse pathogenicity of oral mitis group streptococci.
Collapse
Affiliation(s)
- Nobuo Okahashi
- Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.,Center for Frontier Oral Science, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Masanobu Nakata
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hirotaka Kuwata
- Department of Oral Microbiology and Immunology, School of Dentistry, Showa University, Shinagawa, Tokyo, Japan
| | - Shigetada Kawabata
- Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| |
Collapse
|
24
|
Kuchma SL, O'Toole GA. Surface-Induced cAMP Signaling Requires Multiple Features of the Pseudomonas aeruginosa Type IV Pili. J Bacteriol 2022; 204:e0018622. [PMID: 36073942 DOI: 10.1128/jb.00186-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pseudomonas aeruginosa type IV pili (TFP) are important for twitching motility and biofilm formation. TFP have been implicated in surface sensing, a process whereby surface-engaged cells upregulate the synthesis of the second messenger cAMP to propagate a signaling cascade leading to biofilm initiation and repression of motility. Here, we showed that mutations in PilA impairing proteolytic processing of the prepilin into mature pilin as well as the disruption of essential TFP components, including the PilC platform protein and PilB assembly motor protein, fail to induce surface-dependent cAMP signaling. We showed that TFP retraction by surface-engaged cells was required to induce signaling and that the retractile motor PilT was both necessary and sufficient to power surface-specific induction of cAMP. Furthermore, full TFP function required to support twitching motility is not required for robust cAMP signalling. The PilU retraction motor, in contrast, was unable to support full signaling in the absence of PilT. Finally, while we confirmed that PilA and PilJ interacted by bacterial two-hybrid analysis, our data do not support the current model that PilJ-PilA interaction drives cAMP signaling. IMPORTANCE Surface sensing by P. aeruginosa requires TFP. TFP plays a critical role in the induction of the second messenger cAMP upon surface contact; this second messenger is part of a larger cascade involved in the transition from a planktonic to a biofilm lifestyle. Here, we showed that TFP must be deployed and actively retracted by the PilT motor for the full induction of cAMP signaling. Furthermore, the mechanism whereby TFP retraction triggers cAMP induction is not well understood, and our data argue against one of the current models in the field proposed to address this knowledge gap.
Collapse
|
25
|
He RL, Wu J, Cheng ZH, Li HH, Liu JQ, Liu DF, Li WW. Biomolecular Insights into Extracellular Pollutant Reduction Pathways of Geobacter sulfurreducens Using a Base Editor System. Environ Sci Technol 2022; 56:12247-12256. [PMID: 35960254 DOI: 10.1021/acs.est.2c02756] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Geobacter species are critically involved in elemental biogeochemical cycling and environmental bioremediation processes via extracellular electron transfer (EET), but the underlying biomolecular mechanisms remain elusive due to lack of effective analytical tools to explore into complicated EET networks. Here, a simple and highly efficient cytosine base editor was developed for engineering of the slow-growing Geobacter sulfurreducens (a doubling time of 5 h with acetate as the electron donor and fumarate as the electron acceptor). A single-plasmid cytosine base editor (pYYDT-BE) was constructed in G. sulfurreducens by fusing cytosine deaminase, Cas9 nickase, and a uracil glycosylase inhibitor. This system enabled single-locus editing at 100% efficiency and showed obvious preference at the cytosines in a TC, AC, or CC context than in a GC context. Gene inactivation tests confirmed that it could effectively edit 87.7-93.4% genes of the entire genome in nine model Geobacter species. With the aid of this base editor to construct a series of G. sulfurreducens mutants, we unveiled important roles of both pili and outer membrane c-type cytochromes in long-range EET, thereby providing important evidence to clarify the long-term controversy surrounding their specific roles. Furthermore, we find that pili were also involved in the extracellular reduction of uranium and clarified the key roles of the ExtHIJKL conduit complex and outer membrane c-type cytochromes in the selenite reduction process. This work developed an effective base editor tool for the genetic modification of Geobacter species and provided new insights into the EET network, which lay a basis for a better understanding and engineering of these microbes to favor environmental applications.
Collapse
Affiliation(s)
- Ru-Li He
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
- University of Science and Technology of China-City University of Hong Kong Joint Advanced Research Center, Suzhou Institute for Advance Research of USTC, Suzhou 215123, China
| | - Jie Wu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
- University of Science and Technology of China-City University of Hong Kong Joint Advanced Research Center, Suzhou Institute for Advance Research of USTC, Suzhou 215123, China
| | - Zhou-Hua Cheng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
| | - Hui-Hui Li
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
| | - Jia-Qi Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
| | - Dong-Feng Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
| | - Wen-Wei Li
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science & Technology of China, Hefei 230026, China
- University of Science and Technology of China-City University of Hong Kong Joint Advanced Research Center, Suzhou Institute for Advance Research of USTC, Suzhou 215123, China
| |
Collapse
|
26
|
Habouria H, Bessaiah H, Pokharel P, Dhakal S, Maris S, Buron J, Houle S, Dozois CM. A Newly Identified Group of P-like (PL) Fimbria Genes from Extraintestinal Pathogenic Escherichia coli (ExPEC) Encode Distinct Adhesin Subunits and Mediate Adherence to Host Cells. Appl Environ Microbiol 2022; 88:e0142121. [PMID: 35758695 DOI: 10.1128/aem.01421-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Fimbrial adhesins promote bacterial adherence and biofilm formation. Sequencing of avian pathogenic Escherichia coli (APEC) strain QT598 identified new fimbriae belonging to the π group, which we named PL (P-like) fimbriae since the genetic organization and sequence are similar to those of P and related fimbriae. Genes encoding PL fimbriae located on IncF plasmids are present in diverse E. coli isolates from poultry, human systemic infections, and other sources. As with P fimbriae, PL fimbriae exhibit divergence in adhesin-encoding genes and could be divided into 5 classes based on sequence differences in the PlfG adhesin. plf genes from two predominant PlfG adhesin classes, PlfG class I (PlfGI) and PlfGII, were cloned. PL fimbriae were visualized by electron microscopy, associated with increased biofilm, demonstrated distinct hemagglutination profiles, and promoted adherence to human bladder and kidney epithelial cells. The genes encoding hybrid fimbriae were comprised of genes from plfQT598, wherein plfG was replaced by papG; the adhesin-encoding genes were also functional and mediated adherence to epithelial cells, demonstrating compatibility between the components of these two types of fimbriae. Deletion of plf genes did not reduce colonization of the mouse urinary tract in a single-strain infection model. In contrast, loss of plf genes significantly reduced competitive colonization in the mouse kidneys. Furthermore, plf gene expression was increased over 40-fold in the bladder compared to during in vitro culture. Overall, PL fimbriae represent a new group of fimbriae demonstrating both functional differences from and similarities to P fimbriae, which mediated adherence to host cells and improved competitive colonization of the mouse kidney. IMPORTANCE Fimbriae are important colonization factors in many bacterial species. The identification of a new type of fimbriae encoded on some IncF plasmids in E. coli was investigated. Genomic sequences demonstrated these fimbrial gene clusters have genetic diversity, particularly in the adhesin-encoding plfG gene. Functional studies demonstrated differences in hemagglutination specificity, although both types of Plf adhesin under study mediated adherence to human urinary epithelial cells. A plf mutant also showed decreased colonization of the kidneys in a mouse competitive infection model. PL fimbriae may represent previously unrecognized adhesins that could contribute to host specificity and tissue tropism of some E. coli strains.
Collapse
|
27
|
Hadjineophytou C, Anonsen JH, Svingerud T, Mortimer TD, Grad YH, Scott NE, Koomey M. Sculpting the Bacterial O-Glycoproteome: Functional Analyses of Orthologous Oligosaccharyltransferases with Diverse Targeting Specificities. mBio 2022; 13:e0379721. [PMID: 35471082 PMCID: PMC9239064 DOI: 10.1128/mbio.03797-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 03/25/2022] [Indexed: 11/24/2022] Open
Abstract
Protein glycosylation systems are widely recognized in bacteria, including members of the genus Neisseria. In most bacterial species, the molecular mechanisms and evolutionary contexts underpinning target protein selection and the glycan repertoire remain poorly understood. Broad-spectrum O-linked protein glycosylation occurs in all human-associated species groups within the genus Neisseria, but knowledge of their individual glycoprotein repertoires is limited. Interestingly, PilE, the pilin subunit of the type IV pilus (Tfp) colonization factor, is glycosylated in Neisseria gonorrhoeae and Neisseria meningitidis but not in the deeply branching species N. elongata subsp. glycolytica. To examine this in more detail, we assessed PilE glycosylation status across the genus and found that PilEs of commensal clade species are not modified by the gonococcal PglO oligosaccharyltransferase. Experiments using PglO oligosaccharyltransferases from across the genus expressed in N. gonorrhoeae showed that although all were capable of broad-spectrum protein glycosylation, those from a deep-branching group of commensals were unable to support resident PilE glycosylation. Further glycoproteomic analyses of these strains using immunoblotting and mass spectrometry revealed other proteins differentially targeted by otherwise remarkably similar oligosaccharyltransferases. Finally, we generated pglO allelic chimeras that begin to localize PglO protein domains associated with unique substrate targeting activities. These findings reveal previously unappreciated differences within the protein glycosylation systems of highly related bacterial species. We propose that the natural diversity manifest in the neisserial protein substrates and oligosaccharyltransferases has significant potential to inform the structure-function relationships operating in these and related bacterial protein glycosylation systems. IMPORTANCE Although general protein glycosylation systems have been well recognized in prokaryotes, the processes governing their distribution, function, and evolution remain poorly understood. Here, we have begun to address these gaps in knowledge by comparative analyses of broad-spectrum O-linked protein glycosylation manifest in species within the genus Neisseria that strictly colonize humans. Using N. gonorrhoeae as a well-defined model organism in conjunction with comparative genomics, intraspecies gene complementation, and glycoprotein phenotyping, we discovered clear differences in both glycosylation susceptibilities and enzymatic targeting activities of otherwise largely conserved proteins. These findings reveal previously unappreciated differences within the protein glycosylation systems of highly related bacterial species. We propose that the natural diversity manifest within Neisseria species has significant potential to elucidate the structure-function relationships operating in these and related systems and to inform novel approaches to applied glycoengineering strategies.
Collapse
Affiliation(s)
- Chris Hadjineophytou
- Department of Biosciences, Section for Genetics and Evolutionary Biology, University of Oslo, Oslo, Norway
| | - Jan Haug Anonsen
- Department of Biosciences, Section for Genetics and Evolutionary Biology, University of Oslo, Oslo, Norway
| | - Tina Svingerud
- Department of Biosciences, Section for Genetics and Evolutionary Biology, University of Oslo, Oslo, Norway
| | - Tatum D. Mortimer
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Yonatan H. Grad
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Nichollas E. Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Michael Koomey
- Department of Biosciences, Section for Genetics and Evolutionary Biology, University of Oslo, Oslo, Norway
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
| |
Collapse
|
28
|
|
29
|
Patil PD, Zheng H, Burns FN, Ibanez ACS, Jin Y, Luk YY. Chimeric Ligands of Pili and Lectin A Inhibit Tolerance, Persistence, and Virulence Factors of Pseudomonas aeruginosa over a Wide Range of Phenotypes. ACS Infect Dis 2022; 8:1582-1593. [PMID: 35658414 PMCID: PMC9379910 DOI: 10.1021/acsinfecdis.2c00201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Bacteria readily
form resilient phenotypes to counter environmental
and antibiotic stresses. Here, we demonstrate a class of small molecules
that inhibit a wide range of Pseudomonas aeruginosa phenotypes and enable antibiotics to kill previously tolerant bacteria,
preventing the transition of tolerant bacteria into a persistent population.
We identified two proteins, type IV pili and lectin LecA, as receptors
for our molecules by methods including a new label-free assay based
on bacterial motility sensing the chemicals in the environment, the
chemical inhibition of bacteriophage adsorption on pili appendages
of bacteria, and fluorescence polarization. Structure–activity
relationship studies reveal a molecule that inhibits only pili appendage
and a class of chimeric ligands that inhibit both LecA and pili. Important
structural elements of the ligand are identified for each protein.
This selective ligand binding identifies the phenotypes each protein
receptor controls. Inhibiting LecA results in reducing biofilm formation,
eliminating small colony variants, and is correlated with killing
previously tolerant bacteria. Inhibiting pili appendages impedes swarming
and twitching motilities and pyocyanin and elastase production. Because
these phenotypes are controlled by a broad range of signaling pathways,
this approach simultaneously controls the multiple signaling mechanisms
preventing bacteria to elude antibiotic treatments.
Collapse
Affiliation(s)
- Pankaj D Patil
- Department of Chemistry, Syracuse University, 1-014 Center of Science and Technology, Syracuse, New York 13244-4100, United States
| | - Hewen Zheng
- Department of Chemistry, Syracuse University, 1-014 Center of Science and Technology, Syracuse, New York 13244-4100, United States
| | - Felicia N Burns
- Department of Chemistry, Syracuse University, 1-014 Center of Science and Technology, Syracuse, New York 13244-4100, United States
| | - Arizza C S Ibanez
- Department of Chemistry, Syracuse University, 1-014 Center of Science and Technology, Syracuse, New York 13244-4100, United States
| | - Yuchen Jin
- Department of Chemistry, Syracuse University, 1-014 Center of Science and Technology, Syracuse, New York 13244-4100, United States
| | - Yan-Yeung Luk
- Department of Chemistry, Syracuse University, 1-014 Center of Science and Technology, Syracuse, New York 13244-4100, United States
| |
Collapse
|
30
|
Lacasse M, Valentin AS, Corvec S, Bémer P, Jolivet-Gougeon A, Plouzeau C, Tandé D, Mereghetti L, Bernard L, Lartigue MF. Genotypic Characterization and Biofilm Production of Group B Streptococcus Strains Isolated from Bone and Joint Infections. Microbiol Spectr 2022; 10:e0232921. [PMID: 35357222 PMCID: PMC9045227 DOI: 10.1128/spectrum.02329-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/07/2022] [Indexed: 11/20/2022] Open
Abstract
Bone and joint infections (BJI) represent the second cause of invasive Group B Streptococcus (GBS) infections. Biofilm formation plays a major role in BJI. This study's aim was to analyze the genetic features and biofilm production of GBS strains. In six French laboratories, 77 GBS strains isolated from BJI and 57 strains from vaginal human colonization (Hcol) were characterized and compared by Multi-Locus Sequence Typing (MLST). PCR was used to search for the adhesins (bsaB, lmb, scpB, fbsA, fbsB, hvgA, bibA, bca, srr-1, and srr-2) and Pilus Islands (PI) related genes (PI-1, PI-2a, PI-2b). Biofilm production was studied by crystal violet assay. Strains were categorized into three groups, based on Specific Biofilm Formation (SBF) values defined as: weak, moderate, or strong producers. Molecular study revealed three major clonal complexes (CC) in BJI strains: CC1 (42%), CC23 (22%) and CC10 (14%). Several associations between CC and adhesin/pili were identified: CC1 with srr2, PI-1 + 2a; CC10 with srr-1, bca, PI-1 + 2a; CC17 with fbsB, hvgA, srr-2, PI-1+PI-2b; CC19 with bibA, srr-1, PI-1 + 2a; CC23 with fbsB, bibA, srr-1, PI-2a. The biofilm production was significantly different according to CC, adhesins and pili gene detection. CC10, CC23 and strains harboring fbsB produce more biofilm than CC1, PI-1 + 2a (independently). Finally, SBF values were significantly stronger for Hcol strains rather than for BJI strains (76% versus 40%). This study revealed that Hcol strains appeared to produce stronger biofilm than BJI strains, though they belonged to similar CCs and had the same adhesin and pili content. IMPORTANCE Bone and joint infections (BJI) are pathologies that can be life-threatening and result in compromised functional prognosis for patients. Relapses are common and often related to biofilm formation. Group B streptococci (GBS) BJI increased since the last decade. However, few data are available on this subject in the literature. Our study aims to highlight genotype and biofilm production of GBS isolates from BJI. Seventy-seven GBS strains isolated from BJI and 57 from asymptomatic human vaginal colonization were characterized by multilocus sequence typing (MLST), adhesins content, nature of the pili and the ability to form biofilm. Our results revealed that vaginal human colonization strains produced stronger biofilm than BJI strains, despite belonging to the same phylogenetic lineage and having the same adhesin and pili content.
Collapse
Affiliation(s)
| | - Anne-Sophie Valentin
- Université de Tours, INRAE, ISP, Tours, France
- Centre Hospitalier Universitaire de Tours, Service de Bactériologie, Virologie et Hygiène Hospitalière, Tours, France
| | - Stéphane Corvec
- University Hospital Center of Nantes, Bacteriology Department, Nantes University, Nantes, France
| | - Pascale Bémer
- University Hospital Center of Nantes, Bacteriology Department, Nantes University, Nantes, France
| | - Anne Jolivet-Gougeon
- University of Rennes, INSERM, University Hospital of Rennes, NUMECAN Institute (Nutrition Metabolisms and Cancer), Rennes, France
| | - Chloé Plouzeau
- Bacteriology-Hospital Hygiene Department, University Hospital of Poitiers, Poitiers University, Poitiers, France
| | - Didier Tandé
- Bacteriology-Hospital Hygiene Department, University Hospital of Brest, Brest University, Brest, France
| | - Laurent Mereghetti
- Université de Tours, INRAE, ISP, Tours, France
- Centre Hospitalier Universitaire de Tours, Service de Bactériologie, Virologie et Hygiène Hospitalière, Tours, France
| | - Louis Bernard
- Centre Hospitalier Universitaire de Tours, Service de Maladies infectieuses, Tours, France
| | - Marie-Frédérique Lartigue
- Université de Tours, INRAE, ISP, Tours, France
- Centre Hospitalier Universitaire de Tours, Service de Bactériologie, Virologie et Hygiène Hospitalière, Tours, France
| |
Collapse
|
31
|
Burcham LR, Bath JR, Werlang CA, Lyon LM, Liu N, Evans C, Ribbeck K, Doran KS. Role of MUC5B during Group B Streptococcal Vaginal Colonization. mBio 2022; 13:e0003922. [PMID: 35323039 PMCID: PMC9040740 DOI: 10.1128/mbio.00039-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 03/07/2022] [Indexed: 12/27/2022] Open
Abstract
The female reproductive tract (FRT) is a complex environment, rich in mucin glycoproteins that form a dense network on the surface of the underlying epithelia. Group B Streptococcus (GBS) asymptomatically colonizes 25-30% of healthy women, but during pregnancy can cause ascending infection in utero or be transmitted to the newborn during birth to cause invasive disease. Though the cervicovaginal mucosa is a natural site for GBS colonization, the specific interactions between GBS and mucins remain unknown. Here we demonstrate for the first time that MUC5B interacts directly with GBS and promotes barrier function by inhibiting both bacterial attachment to human epithelial cells and ascension from the vagina to the uterus in a murine model of GBS colonization. RNA sequencing analysis of GBS exposed to MUC5B identified 128 differentially expressed GBS genes, including upregulation of the pilus island-2b (PI-2b) locus. We subsequently show that PI-2b is important for GBS attachment to reproductive cells, binding to immobilized mucins, and vaginal colonization in vivo. Our results suggest that while MUC5B plays an important role in host defense, GBS upregulates pili in response to mucins to help promote persistence within the vaginal tract, illustrating the dynamic interplay between pathogen and host. IMPORTANCE Mucin glycoproteins are a major component that contributes to the complexity of the female reproductive tract (FRT). Group B Streptococcus (GBS) is present in the FRT of 25-30% of healthy women, but during pregnancy can ascend to the uterus to cause preterm birth and fetal infection in utero. Here we show that a prominent mucin found in the FRT, MUC5B, promotes host defense by inhibiting GBS interaction with epithelial cells found in the FRT and ascension from the vagina to the uterus in vivo. In response to MUC5B, GBS induces the expression of surface expressed pili, which in turn contributes to GBS persistence within the vaginal lumen. These observations highlight the importance and complexity of GBS-mucin interactions that warrant further investigation.
Collapse
Affiliation(s)
- Lindsey R. Burcham
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jade R. Bath
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Caroline A. Werlang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Laurie M. Lyon
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Naoko Liu
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Christopher Evans
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Katharina Ribbeck
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Kelly S. Doran
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| |
Collapse
|
32
|
Hiippala K, Khan I, Ronkainen A, Boulund F, Vähä-Mäkilä H, Suutarinen M, Seifert M, Engstrand L, Satokari R. Novel strain of Pseudoruminococcus massiliensis possesses traits important in gut adaptation and host-microbe interactions. Gut Microbes 2022; 14:2013761. [PMID: 34965174 PMCID: PMC8726730 DOI: 10.1080/19490976.2021.2013761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Fecal microbiota transplantation (FMT) is an efficient treatment for recurrent Clostridioides difficile infection and currently investigated as a treatment for other intestinal and systemic diseases. Better understanding of the species potentially transferred in FMT is needed. We isolated from a healthy fecal donor a novel strain E10-96H of Pseudoruminococcus massiliensis, a recently described strictly anaerobic species currently represented only by the type strain. The whole genome sequence of E10-96H had over 98% similarity with the type strain. E10-96H carries 20 glycoside hydrolase encoding genes, degrades starch in vitro and thus may contribute to fiber degradation, cross-feeding of other species and butyrate production in the intestinal ecosystem. The strain carries pilus-like structures, harbors pilin genes in its genome and adheres to enterocytes in vitro but does not provoke a proinflammatory response. P. massiliensis seems to have commensal behavior with the host epithelium, and its role in intestinal ecology should be studied further.
Collapse
Affiliation(s)
- Kaisa Hiippala
- Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Imran Khan
- Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Aki Ronkainen
- Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Fredrik Boulund
- Centre for Translational Microbiome Research, Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Helena Vähä-Mäkilä
- Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Maiju Suutarinen
- Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Maike Seifert
- Centre for Translational Microbiome Research, Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Lars Engstrand
- Centre for Translational Microbiome Research, Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Reetta Satokari
- Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland,CONTACT Reetta Satokari Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| |
Collapse
|
33
|
Wendt KE, Walker P, Sengupta A, Ungerer J, Pakrasi HB. Engineering Natural Competence into the Fast-Growing Cyanobacterium Synechococcus elongatus Strain UTEX 2973. Appl Environ Microbiol 2022; 88:e0188221. [PMID: 34705549 PMCID: PMC8752150 DOI: 10.1128/aem.01882-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/25/2021] [Indexed: 11/20/2022] Open
Abstract
Natural transformation is the process by which bacteria actively take up and integrate extracellular DNA into their genomes. In cyanobacteria, natural transformation has only been experimentally demonstrated in a few species. Although cyanobacteria are important model systems for studying photosynthesis and circadian cycling, natural transformation in cyanobacteria has not been characterized to the degree that the process has been studied in other Gram-negative bacteria. Two cyanobacterial species that are 99.8% genetically identical provide a unique opportunity to better understand the nuances of natural transformation in cyanobacteria: Synechococcus elongatus PCC 7942 and Synechococcus elongatus UTEX 2973 (hereafter called Synechococcus 7942 and Synechococcus 2973, respectively). Synechococcus 7942 is a naturally transformable model system, while Synechococcus 2973 is a recently discovered species that is not naturally competent. Taking only 1.5 h to replicate, Synechococcus 2973 is the fastest-growing cyanobacterial species known and thus is a strong candidate for serving as a model organism. However, its inability to undergo natural transformation has prevented it from becoming a widely used model system. By substituting polymorphic alleles from Synechococcus 7942 for native Synechococcus 2973 alleles, natural transformation was introduced into Synechococcus 2973. Two genetic loci were found to be involved in differential natural competence between the two organisms: transformation pilus component pilN and circadian transcriptional master regulator rpaA. By using targeted genome editing and enrichment outgrowth, a strain that was both naturally transformable and fast-growing was created. This new Synechococcus 2973-T strain will serve as a valuable resource to the cyanobacterial research community. IMPORTANCE Certain bacterial species have the ability to take up naked extracellular DNA and integrate it into their genomes. This process is known as natural transformation and is widely considered to play a major role in bacterial evolution. Because of the ease of introducing new genes into naturally transformable organisms, this capacity is also highly valued in the laboratory. Cyanobacteria are photosynthetic and can therefore serve as model systems for some important aspects of plant physiology. Here, we describe the creation of a modified cyanobacterial strain (Synechococcus 2973-T) that is capable of undergoing natural transformation and has a replication time on par with that of the fastest-growing cyanobacterium discovered to date. This new cyanobacterium has the potential to serve as a new model organism for the cyanobacterial research community and will allow experiments to be completed in a fraction of the time it has taken to complete previous assays.
Collapse
Affiliation(s)
- Kristen E. Wendt
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Patricia Walker
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Annesha Sengupta
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Justin Ungerer
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | | |
Collapse
|
34
|
Abstract
Cyanobacteria rely on photosynthesis, and thus have evolved complex responses to light. These include phototaxis, the ability of cells to sense light direction and move towards or away from it. Analysis of mutants has demonstrated that phototaxis requires the coordination of multiple photoreceptors and signal transduction networks. The output of these networks is relayed to type IV pili (T4P) that attach to and exert forces on surfaces or other neighboring cells to drive “twitching” or “gliding” motility. This, along with the extrusion of polysaccharides or “slime” by cells, facilitates the emergence of group behavior. We evaluate recent models that describe the emergence of collective colony-scale behavior from the responses of individual, interacting cells. We highlight the advantages of “active matter” approaches in the study of bacterial communities, discussing key differences between emergent behavior in cyanobacterial phototaxis and similar behavior in chemotaxis or quorum sensing.
Collapse
|
35
|
Zegeye ED, Pradhan B, Llarena AK, Aspholm M. Enigmatic Pilus-Like Endospore Appendages of Bacillus cereus Group Species. Int J Mol Sci 2021; 22:12367. [PMID: 34830248 PMCID: PMC8619143 DOI: 10.3390/ijms222212367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 11/16/2022] Open
Abstract
The endospores (spores) of many Bacillus cereus sensu lato species are decorated with multiple hair/pilus-like appendages. Although they have been observed for more than 50 years, all efforts to characterize these fibers in detail have failed until now, largely due to their extraordinary resilience to proteolytic digestion and chemical solubilization. A recent structural analysis of B. cereus endospore appendages (Enas) using cryo-electron microscopy has revealed the structure of two distinct fiber morphologies: the longer and more abundant "Staggered-type" (S-Ena) and the shorter "Ladder-like" type (L-Ena), which further enabled the identification of the genes encoding the S-Ena. Ena homologs are widely and uniquely distributed among B. cereus sensu lato species, suggesting that appendages play important functional roles in these species. The discovery of ena genes is expected to facilitate functional studies involving Ena-depleted mutant spores to explore the role of Enas in the interaction between spores and their environment. Given the importance of B. cereus spores for the food industry and in medicine, there is a need for a better understanding of their biological functions and physicochemical properties. In this review, we discuss the current understanding of the Ena structure and the potential roles these remarkable fibers may play in the adhesion of spores to biotic and abiotic surfaces, aggregation, and biofilm formation.
Collapse
Affiliation(s)
- Ephrem Debebe Zegeye
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432 Ås, Norway; (E.D.Z.); (A.-K.L.)
| | - Brajabandhu Pradhan
- Structural and Molecular Microbiology, VIB-VUB Center for Structural Biology, VIB, 1050 Brussels, Belgium;
- Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Ann-Katrin Llarena
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432 Ås, Norway; (E.D.Z.); (A.-K.L.)
| | - Marina Aspholm
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432 Ås, Norway; (E.D.Z.); (A.-K.L.)
| |
Collapse
|
36
|
Liu X, Walker DJF, Nonnenmann SS, Sun D, Lovley DR. Direct Observation of Electrically Conductive Pili Emanating from Geobacter sulfurreducens. mBio 2021; 12:e0220921. [PMID: 34465020 PMCID: PMC8406130 DOI: 10.1128/mbio.02209-21] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 11/20/2022] Open
Abstract
Geobacter sulfurreducens is a model microbe for elucidating the mechanisms for extracellular electron transfer in several biogeochemical cycles, bioelectrochemical applications, and microbial metal corrosion. Multiple lines of evidence previously suggested that electrically conductive pili (e-pili) are an essential conduit for long-range extracellular electron transport in G. sulfurreducens. However, it has recently been reported that G. sulfurreducens does not express e-pili and that filaments comprised of multi-heme c-type cytochromes are responsible for long-range electron transport. This possibility was directly investigated by examining cells, rather than filament preparations, with atomic force microscopy. Approximately 90% of the filaments emanating from wild-type cells had a diameter (3 nm) and conductance consistent with previous reports of e-pili harvested from G. sulfurreducens or heterologously expressed in Escherichia coli from the G. sulfurreducens pilin gene. The remaining 10% of filaments had a morphology consistent with filaments comprised of the c-type cytochrome OmcS. A strain expressing a modified pilin gene designed to yield poorly conductive pili expressed 90% filaments with a 3-nm diameter, but greatly reduced conductance, further indicating that the 3-nm diameter conductive filaments in the wild-type strain were e-pili. A strain in which genes for five of the most abundant outer-surface c-type cytochromes, including OmcS, were deleted yielded only 3-nm-diameter filaments with the same conductance as in the wild type. These results demonstrate that e-pili are the most abundant conductive filaments expressed by G. sulfurreducens, consistent with previous functional studies demonstrating the need for e-pili for long-range extracellular electron transfer. IMPORTANCE Electroactive microbes have significant environmental impacts, as well as applications in bioenergy and bioremediation. The composition, function, and even existence of electrically conductive pili (e-pili) has been one of the most contentious areas of investigation in electromicrobiology, in part because e-pili offer a mechanism for long-range electron transport that does not involve the metal cofactors common in much of biological electron transport. This study demonstrates that e-pili are abundant filaments emanating from Geobacter sulfurreducens, which serves as a model for long-range extracellular electron transfer in direct interspecies electron transfer, dissimilatory metal reduction, microbe-electrode exchange, and corrosion caused by direct electron uptake from Fe(0). The methods described in this study provide a simple strategy for evaluating the distribution of conductive filaments throughout the microbial world with an approach that avoids artifactual production and/or enrichment of filaments that may not be physiologically relevant.
Collapse
Affiliation(s)
- Xinying Liu
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, China
| | - David J. F. Walker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Stephen S. Nonnenmann
- Institute for Applied Life Sciences, university of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Department of Mechanical and Industrial Engineering, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| | - Dezhi Sun
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, China
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Institute for Applied Life Sciences, university of Massachusetts—Amherst, Amherst, Massachusetts, USA
| |
Collapse
|
37
|
Abstract
Bacteria thrive both in liquids and attached to surfaces. The concentration of bacteria on surfaces is generally much higher than in the surrounding environment, offering bacteria ample opportunity for mutualistic, symbiotic, and pathogenic interactions. To efficiently populate surfaces, they have evolved mechanisms to sense mechanical or chemical cues upon contact with solid substrata. This is of particular importance for pathogens that interact with host tissue surfaces. In this review we discuss how bacteria are able to sense surfaces and how they use this information to adapt their physiology and behavior to this new environment. We first survey mechanosensing and chemosensing mechanisms and outline how specific macromolecular structures can inform bacteria about surfaces. We then discuss how mechanical cues are converted to biochemical signals to activate specific cellular processes in a defined chronological order and describe the role of two key second messengers, c-di-GMP and cAMP, in this process.
Collapse
Affiliation(s)
| | - Urs Jenal
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland; ,
| |
Collapse
|
38
|
Affiliation(s)
- Magnus Hook
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, United States
| | - Timothy J Foster
- Microbiology Department, Trinity College Dublin, Dublin, Ireland
| |
Collapse
|
39
|
McConnell SA, McAllister RA, Amer BR, Mahoney BJ, Sue CK, Chang C, Ton-That H, Clubb RT. Sortase-assembled pili in Corynebacterium diphtheriae are built using a latch mechanism. Proc Natl Acad Sci U S A 2021; 118:e2019649118. [PMID: 33723052 DOI: 10.1073/pnas.2019649118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Gram-positive bacteria assemble pili (fimbriae) on their surfaces to adhere to host tissues and to promote polymicrobial interactions. These hair-like structures, although very thin (1 to 5 nm), exhibit impressive tensile strengths because their protein components (pilins) are covalently crosslinked together via lysine-isopeptide bonds by pilus-specific sortase enzymes. While atomic structures of isolated pilins have been determined, how they are joined together by sortases and how these interpilin crosslinks stabilize pilus structure are poorly understood. Using a reconstituted pilus assembly system and hybrid structural biology methods, we elucidated the solution structure and dynamics of the crosslinked interface that is repeated to build the prototypical SpaA pilus from Corynebacterium diphtheriae We show that sortase-catalyzed introduction of a K190-T494 isopeptide bond between adjacent SpaA pilins causes them to form a rigid interface in which the LPLTG sorting signal is inserted into a large binding groove. Cellular and quantitative kinetic measurements of the crosslinking reaction shed light onto the mechanism of pilus biogenesis. We propose that the pilus-specific sortase in C. diphtheriae uses a latch mechanism to select K190 on SpaA for crosslinking in which the sorting signal is partially transferred from the enzyme to a binding groove in SpaA in order to facilitate catalysis. This process is facilitated by a conserved loop in SpaA, which after crosslinking forms a stabilizing latch that covers the K190-T494 isopeptide bond. General features of the structure and sortase-catalyzed assembly mechanism of the SpaA pilus are likely conserved in Gram-positive bacteria.
Collapse
|
40
|
Andrade A, Hernández-Eligio A, Tirado AL, Vega-Alvarado L, Olvera M, Morett E, Juárez K. Specialization of the Reiterated Copies of the Heterodimeric Integration Host Factor Genes in Geobacter sulfurreducens. Front Microbiol 2021; 12:626443. [PMID: 33737919 PMCID: PMC7962754 DOI: 10.3389/fmicb.2021.626443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/14/2021] [Indexed: 12/13/2022] Open
Abstract
Integration host factor (IHF) is a widely distributed small heterodimeric protein member of the bacterial Nucleoid-Associated Proteins (NAPs), implicated in multiple DNA regulatory processes. IHF recognizes a specific DNA sequence and induces a large bend of the nucleic acid. IHF function has been mainly linked with the regulation of RpoN-dependent promoters, where IHF commonly recognizes a DNA sequence between the enhancer-binding region and the promoter, facilitating a close contact between the upstream bound activator and the promoter bound, RNA polymerase. In most proteobacteria, the genes encoding IHF subunits (ihfA and ihfB) are found in a single copy. However, in some Deltaproteobacteria, like Geobacter sulfurreducens, those genes are duplicated. To date, the functionality of IHF reiterated encoding genes is unknown. In this work, we achieved the functional characterization of the ihfA-1, ihfA-2, ihfB-1, and ihfB-2 from G. sulfurreducens. Unlike the ΔihfA-2 or ΔihfB-1 strains, single gene deletion in ihfA-1 or ihfB-2, provokes an impairment in fumarate and Fe(III) citrate reduction. Accordingly, sqRT-PCR experiments showed that ihfA-1 and ihfB-2 were expressed at higher levels than ihfA-2 and ihfB-1. In addition, RNA-Seq analysis of the ΔihfA-1 and ΔihfB-2 strains revealed a total of 89 and 122 differentially expressed genes, respectively. Furthermore, transcriptional changes in 25 genes were shared in both mutant strains. Among these genes, we confirmed the upregulation of the pilA-repressor, GSU1771, and downregulation of the triheme-cytochrome (pgcA) and the aconitate hydratase (acnA) genes by RT-qPCR. EMSA experiments also demonstrated the direct binding of IHF to the upstream promoter regions of GSU1771, pgcA and acnA. PilA changes in ΔihfA-1 and ΔihfB-2 strains were also verified by immunoblotting. Additionally, heme-staining of subcellular fractions in ΔihfA-1 and ΔihfB-2 strains revealed a remarkable deficit of c-type cytochromes. Overall, our data indicate that at least during fumarate and Fe(III) citrate reduction, the functional IHF regulator is likely assembled by the products of ihfA-1 and ihfB-2. Also, a role of IHF controlling expression of multiple genes (other than RpoN-dependent) affects G. sulfurreducens physiology and extracellular electron transfer.
Collapse
Affiliation(s)
- Angel Andrade
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.,Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey, Mexico
| | - Alberto Hernández-Eligio
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.,CONACYT, Ciudad de México, Mexico
| | - Ana Lilia Tirado
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Leticia Vega-Alvarado
- Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Mexico
| | - Maricela Olvera
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Enrique Morett
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Katy Juárez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| |
Collapse
|
41
|
Lepp D, Zhou Y, Ojha S, Mehdizadeh Gohari I, Carere J, Yang C, Prescott JF, Gong J. Clostridium perfringens Produces an Adhesive Pilus Required for the Pathogenesis of Necrotic Enteritis in Poultry. J Bacteriol 2021; 203:e00578-20. [PMID: 33468589 DOI: 10.1128/JB.00578-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 01/07/2021] [Indexed: 12/19/2022] Open
Abstract
Clostridium perfringens type G strains cause necrotic enteritis (NE) in poultry, an economically important disease that is a major target of in-feed antibiotics. NE is a multifactorial disease, involving not only the critically important NetB toxin but also additional virulence and virulence-associated factors. We previously identified a C. perfringens chromosomal locus (VR-10B) associated with disease-causing strains that is predicted to encode a sortase-dependent pilus. In the current study, we sought to provide direct evidence for the production of a pilus by C. perfringens and establish its role in NE pathogenesis. Pilus structures in virulent C. perfringens strain CP1 were visualized by transmission electron microscopy (TEM) of immunogold-labeled cells. Filamentous structures were observed extending from the cell surface in wild-type CP1 but not from isogenic pilin-null mutant strains. In addition, immunoblotting of cell surface proteins demonstrated that CP1, but not the null mutant strains, produced a high molecular weight ladder-like pattern characteristic of a pilus polymer. Binding to collagen types I, II, and IV was significantly reduced (Tukey's test, P < 0.01) in all three pilin mutants compared to CP1 and could be specifically blocked by CnaA and FimA antisera, indicating that these pilins participate in adherence. Furthermore, fimA and fimB null mutants were both severely attenuated in their ability to cause disease in an in vivo chicken NE challenge model. Together, these results provide the first direct evidence for the production of a sortase-dependent pilus by C. perfringens and confirm its critical role in NE pathogenesis and collagen binding.IMPORTANCE In necrotic enteritis (NE), an intestinal disease of chickens, Clostridium perfringens cells adhere tightly to damaged intestinal tissue, but the factors involved are not known. We previously discovered a cluster of C. perfringens genes predicted to encode a pilus, a hair-like bacterial surface structure commonly involved in adherence. In the current study, we have directly imaged this pilus using transmission electron microscopy (TEM). We also show that inactivation of the pilus genes stops pilus production, significantly reducing the bacterium's ability to bind collagen and cause disease. Importantly, this is the first direct evidence for the production of a sortase-dependent pilus by C. perfringens, revealing a promising new target for developing therapeutics to combat this economically important disease.
Collapse
|
42
|
Ye Y, Liu X, Nealson KH, Rensing C, Qin S, Zhou S. Dissecting the Structural and Conductive Functions of Nanowires in Geobacter sulfurreducens Electroactive Biofilms. mBio 2021; 13:e0382221. [PMID: 35164556 DOI: 10.1128/mbio.03822-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Conductive nanowires are thought to contribute to long-range electron transfer (LET) in Geobacter sulfurreducens anode biofilms. Three types of nanowires have been identified: pili, OmcS, and OmcZ. Previous studies highlighted their conductive function in anode biofilms, yet a structural function also has to be considered. We present here a comprehensive analysis of the function of nanowires in LET by inhibiting the expression of each nanowire. Meanwhile, flagella with poor conductivity were expressed to recover the structural function but not the conductive function of nanowires in the corresponding nanowire mutant strain. The results demonstrated that pili played a structural but not a conductive function in supporting biofilm formation. In contrast, the OmcS nanowire played a conductive but not a structural function in facilitating electron transfer in the biofilm. The OmcZ nanowire played both a structural and a conductive function to contribute to current generation. Expression of the poorly conductive flagellum was shown to enhance biofilm formation, subsequently increasing current generation. These data support a model in which multiheme cytochromes facilitate long-distance electron transfer in G. sulfurreducens biofilms. Our findings also suggest that the formation of a thicker biofilm, which contributed to a higher current generation by G. sulfurreducens, was confined by the biofilm formation deficiency, and this has applications in microbial electrochemical systems. IMPORTANCE The low power generation of microbial fuel cells limits their utility. Many factors can affect power generation, including inefficient electron transfer in the anode biofilm. Thus, understanding the mechanism(s) of electron transfer provides a pathway for increasing the power density of microbial fuel cells. Geobacter sulfurreducens was shown to form a thick biofilm on the anode. Cells far away from the anode reduce the anode through long-range electron transfer. Based on their conductive properties, three types of nanowires have been hypothesized to directly facilitate long-range electron transfer: pili, OmcS, and OmcZ nanowires. However, their structural contributions to electron transfer in anode biofilm have not been elucidated. Based on studies of mutants lacking one or more of these facilitators, our results support a cytochrome-mediated electron transfer process in Geobacter biofilms and highlight the structural contribution of nanowires in anode biofilm formation, which contributes to biofilm formation and current generation, thereby providing a strategy to increase current generation.
Collapse
|
43
|
Abstract
Streptococcus pyogenes (Group A Streptococcus; GAS) is an exclusively human pathogen. This bacterial species is responsible for a large variety of infections, ranging from purulent but mostly self-limiting oropharynx/skin diseases to streptococcal sequelae, including glomerulonephritis and rheumatic fever, as well as life-threatening streptococcal toxic-shock syndrome. GAS displays a wide array of surface proteins, with antigenicity of the M protein and pili utilized for M- and T-serotyping, respectively. Since the discovery of GAS pili in 2005, their genetic features, including regulation of expression, and structural features, including assembly mechanisms and protein conformation, as well as their functional role in GAS pathogenesis have been intensively examined. Moreover, their potential as vaccine antigens has been studied in detail. Pilus biogenesis-related genes are located in a discrete section of the GAS genome encoding fibronectin and collagen binding proteins and trypsin-resistant antigens (FCT region). Based on the heterogeneity of genetic composition and DNA sequences, this region is currently classified into nine distinguishable forms. Pili and fibronectin-binding proteins encoded in the FCT region are known to be correlated with infection sites, such as the skin and throat, possibly contributing to tissue tropism. As also found for pili of other Gram-positive bacterial pathogens, GAS pilin proteins polymerize via isopeptide bonds, while intramolecular isopeptide bonds present in the pilin provide increased resistance to degradation by proteases. As supported by findings showing that the main subunit is primarily responsible for T-serotyping antigenicity, pilus functions and gene expression modes are divergent. GAS pili serve as adhesins for tonsillar tissues and keratinocyte cell lines. Of note, a minor subunit is considered to have a harpoon function by which covalent thioester bonds with host ligands are formed. Additionally, GAS pili participate in biofilm formation and evasion of the immune system in a serotype/strain-specific manner. These multiple functions highlight crucial roles of pili during the onset of GAS infection. This review summarizes the current state of the art regarding GAS pili, including a new mode of host-GAS interaction mediated by pili, along with insights into pilus expression in terms of tissue tropism.
Collapse
Affiliation(s)
- Masanobu Nakata
- Department of Oral Microbiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Bernd Kreikemeyer
- Institute of Medical Microbiology, Virology and Hygiene, University of Rostock, Rostock, Germany
| |
Collapse
|
44
|
Iovino F, Nannapaneni P, Henriques-Normark B, Normark S. The impact of the ancillary pilus-1 protein RrgA of Streptococcus pneumoniae on colonization and disease. Mol Microbiol 2020; 113:650-658. [PMID: 32185835 DOI: 10.1111/mmi.14451] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 12/11/2022]
Abstract
The Gram-positive bacterium Streptococcus pneumoniae, the pneumococcus, is an important commensal resident of the human nasopharynx. Carriage is usually asymptomatic, however, S. pneumoniae can become invasive and spread from the upper respiratory tract to the lungs causing pneumonia, and to other organs to cause severe diseases such as bacteremia and meningitis. Several pneumococcal proteins important for its disease-causing capability have been described and many are expressed on the bacterial surface. The surface located pneumococcal type-1 pilus has been associated with virulence and the inflammatory response, and it is present in 20%-30% of clinical isolates. Its tip protein RrgA has been shown to be a major adhesin to human cells and to promote invasion through the blood-brain barrier. In this review we discuss recent findings of the impact of RrgA on bacterial colonization of the upper respiratory tract and on pneumococcal virulence, and use epidemiological data and genome-mining to suggest trade-off mechanisms potentially explaining the rather low prevalence of pilus-1 expressing pneumococci in humans.
Collapse
Affiliation(s)
- Federico Iovino
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Priyanka Nannapaneni
- 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.,Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and Lee Kong Chian School of Medicine (LKC), Nanyang Technological University (NTU), Singapore, Singapore
| | - Staffan Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and Lee Kong Chian School of Medicine (LKC), Nanyang Technological University (NTU), Singapore, Singapore
| |
Collapse
|
45
|
Hu LI, Yin S, Ozer EA, Sewell L, Rehman S, Garnett JA, Seifert HS. Discovery of a New Neisseria gonorrhoeae Type IV Pilus Assembly Factor, TfpC. mBio 2020; 11:e02528-20. [PMID: 33109763 DOI: 10.1128/mBio.02528-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Most bacterial species express one or more extracellular organelles called pili/fimbriae that are required for many properties of each bacterial cell. The Neisseria gonorrhoeae type IV pilus is a major virulence and colonization factor for the sexually transmitted infection gonorrhea. We have discovered a new protein of Neisseria gonorrhoeae called TfpC that is required to maintain type IV pili on the bacterial cell surface. There are similar proteins found in other members of the Neisseria genus and many other bacterial species important for human health. Neisseria gonorrhoeae relies on type IV pili (T4p) to promote colonization of their human host and to cause the sexually transmitted infection gonorrhea. This organelle cycles through a process of extension and retraction back into the bacterial cell. Through a genetic screen, we identified the NGO0783 locus of N. gonorrhoeae strain FA1090 as containing a gene encoding a protein required to stabilize the type IV pilus in its extended, nonretracted conformation. We have named the gene tfpC and the protein TfpC. Deletion of tfpC produces a nonpiliated colony morphology, and immuno-transmission electron microscopy confirms that the pili are lost in the ΔtfpC mutant, although there is some pilin detected near the bacterial cell surface. A copy of the tfpC gene expressed from a lac promoter restores pilus expression and related phenotypes. A ΔtfpC mutant shows reduced levels of pilin protein, but complementation with a tfpC gene restored pilin to normal levels. Bioinformatic searches show that there are orthologues in numerous bacterial species, but not all type IV pilin-expressing bacteria contain orthologous genes. Coevolution and nuclear magnetic resonance (NMR) analysis indicates that TfpC contains an N-terminal transmembrane helix, a substantial extended/unstructured region, and a highly charged C-terminal coiled-coil domain.
Collapse
|
46
|
Spacova I, O'Neill C, Lebeer S. Lacticaseibacillus rhamnosus GG inhibits infection of human keratinocytes by Staphylococcus aureus through mechanisms involving cell surface molecules and pH reduction. Benef Microbes 2020; 11:703-715. [PMID: 33084369 DOI: 10.3920/bm2020.0075] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Beneficial bacteria represent an emerging tool against topical diseases, including infection caused by Staphylococcus aureus. Here, we investigated several anti-pathogenic mechanisms of the model probiotic Lacticaseibacillus rhamnosus GG against a clinical S. aureus isolate by implementing various mutants lacking important cell surface molecules. We analysed adhesion of L. rhamnosus and competitive adhesion with S. aureus to primary human keratinocytes, L. rhamnosus and S. aureus auto- and co-aggregation, S. aureus growth inhibition, keratinocyte viability increase, and monocyte Toll-like receptor (TLR) activation by L. rhamnosus as such, or with S. aureus. L. rhamnosus mutated in SpaCBA pili exhibited reduced adhesion to keratinocytes, reduced ability to prevent S. aureus adhesion to keratinocytes and reduced co-aggregation with S. aureus. Mutants in cell wall exopolysaccharides showed enhanced adhesion to keratinocytes and TLR activation in monocytes, suggesting involvement of additional cell surface molecules masked by exopolysaccharides. All L. rhamnosus strains inhibited S. aureus growth, likely due to acidification of the medium. Live (but not UV-inactivated) L. rhamnosus significantly reduced inflammatory TLR activation in monocytes by S. aureus. These data suggest the key role of SpaCBA pili and additional contribution of other cell surface molecules as well as secreted components of L. rhamnosus GG in the multifactorial inhibition of S. aureus adhesion and toxicity in the skin niche.
Collapse
Affiliation(s)
- I Spacova
- Laboratory of Applied Microbiology and Biotechnology, ENdEMIC group, University of Antwerp, Groenenborgerlaan 171 G.V.522, Antwerp, 2020, Belgium
| | - C O'Neill
- Division of Musculoskeletal & Dermatological Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - S Lebeer
- Laboratory of Applied Microbiology and Biotechnology, ENdEMIC group, University of Antwerp, Groenenborgerlaan 171 G.V.522, Antwerp, 2020, Belgium
| |
Collapse
|
47
|
Abstract
It has been more than a decade since the last comprehensive review of the phase-variable uropathogen-associated pyelonephritis-associated pilus (pap) genetic switch. Since then, important data have come to light, including additional factors that regulate pap expression, better characterization of H-NS regulation, the structure of the Lrp octamer in complex with pap regulatory DNA, the temperature-insensitive phenotype of a mutant lacking the acetyltransferase RimJ, evidence that key components of the regulatory machinery are acetylated, and new insights into the role of DNA binding by key regulators in shaping both the physical structure and regulatory state of the papI and papBA promoters. This review revisits pap, integrating these newer observations with older ones to produce a new model for the concerted behavior of this virulence-regulatory region.
Collapse
Affiliation(s)
- Mario Zamora
- Stritch School of Medicine, Health Sciences Division, Loyola University Chicago, Maywood, Illinois, USA
- Department of Microbiology and Immunology, Stritch School of Medicine, Health Sciences Division, Loyola University Chicago, Maywood, Illinois, USA
| | - Christine A Ziegler
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alan J Wolfe
- Department of Microbiology and Immunology, Stritch School of Medicine, Health Sciences Division, Loyola University Chicago, Maywood, Illinois, USA
| |
Collapse
|
48
|
Rasinkangas P, Tytgat HLP, Ritari J, Reunanen J, Salminen S, Palva A, Douillard FP, de Vos WM. Characterization of Highly Mucus-Adherent Non-GMO Derivatives of Lacticaseibacillus rhamnosus GG. Front Bioeng Biotechnol 2020; 8:1024. [PMID: 32974330 PMCID: PMC7466733 DOI: 10.3389/fbioe.2020.01024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/05/2020] [Indexed: 01/30/2023] Open
Abstract
Lacticaseibacillus rhamnosus GG is one of the best studied lactic acid bacteria in the context of probiotic effects. L. rhamnosus GG has been shown to prevent diarrhea in children and adults and has been implicated to have mitigating or preventive effects in several disorders connected to microbiota dysbiosis. The probiotic effects are largely attributed to its adhesive heterotrimeric sortase-dependent pili, encoded by the spaCBA-srtC1 gene cluster. Indeed, the strain-specific SpaCBA pili have been shown to contribute to adherence, biofilm formation and host signaling. In this work we set out to generate non-GMO derivatives of L. rhamnosus GG that adhere stronger to mucus compared to the wild-type strain using chemical mutagenesis. We selected 13 derivatives that showed an increased mucus-adherent phenotype. Deep shotgun resequencing of the strains enabled division of the strains into three classes, two of which revealed SNPs (single nucleotide polymorphisms) in the spaA and spaC genes encoding the shaft and tip adhesive pilins, respectively. Strikingly, the other class derivatives demonstrated less clear genotype – phenotype relationships, illustrating that pili biogenesis and structure is also affected by other processes. Further characterization of the different classes of derivatives was performed by PacBio SMRT sequencing and RNAseq analysis, which resulted in the identification of molecular candidates driving pilin biosynthesis and functionality. In conclusion, we report on the generation and characterization of three classes of strongly adherent L. rhamnosus GG derivatives that show an increase in adhesion to mucus. These are of special interest as they provide a window on processes and genes driving piliation and its control in L. rhamnosus GG and offer a variety of non-GMO derivatives of this key probiotic strain that are applicable in food products.
Collapse
Affiliation(s)
- Pia Rasinkangas
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Hanne L P Tytgat
- Laboratory of Microbiology, Wageningen University, Wageningen, Netherlands
| | - Jarmo Ritari
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Justus Reunanen
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Seppo Salminen
- Functional Foods Forum, Faculty of Medicine, University of Turku, Turku, Finland
| | - Airi Palva
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - François P Douillard
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Willem M de Vos
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.,Laboratory of Microbiology, Wageningen University, Wageningen, Netherlands.,Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| |
Collapse
|
49
|
Guo G, Du D, Yu Y, Zhang Y, Qian Y, Zhang W. Pan-genome analysis of Streptococcus suis serotype 2 revealed genomic diversity among strains of different virulence. Transbound Emerg Dis 2020; 68:637-647. [PMID: 32654396 DOI: 10.1111/tbed.13725] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 06/26/2020] [Accepted: 07/06/2020] [Indexed: 12/13/2022]
Abstract
Streptococcus suis (SS) is an emerging zoonotic pathogen that causes severe infections in swine and humans. Among the 33 known serotypes, serotype 2 is most frequently associated with infections in pigs and humans. To better understand the virulence characterization of S. suis serotype 2 (SS2) and discriminate the difference between virulent and avirulent strains in SS2, characterization of the genomic features of strains with different virulence is required. The result showed that Streptococcus suis have an open pan-genome. The pan-genome shared by the 19 S. suis serotype 2 strains was composed of 1,239 core genes and 2,436 accessory genes. COG analysis indicated that core genes are involved in the basic physiological function, but accessory genes related to tachytely evolution. Comparative analysis between core genomes of virulent strains and 9 avirulent strains suggested that srtBCD pilus cluster was a significant discrepancy between virulent and avirulent strains. Analysis between high virulent and group B low virulent strains showed 53 and 58 genes specific to each other. Moreover, genomes of avirulent strains tend to be larger than virulent strains; avirulent strains tend to possess more prophages sequences than virulent strains. Our findings could be contributed to a better understanding of the genomics of S. suis serotype 2.
Collapse
Affiliation(s)
- Genglin Guo
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Lab for Swine Streptococcosis, Nanjing, China
| | - Dechao Du
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Lab for Swine Streptococcosis, Nanjing, China
| | - Yanfei Yu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Lab for Swine Streptococcosis, Nanjing, China.,Key Laboratory of Veterinary Biological Engineering and Technology of Ministry of Agriculture, Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Yuhang Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Lab for Swine Streptococcosis, Nanjing, China
| | - Yunyun Qian
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Lab for Swine Streptococcosis, Nanjing, China
| | - Wei Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Lab for Swine Streptococcosis, Nanjing, China
| |
Collapse
|
50
|
Sue CK, McConnell SA, Ellis-Guardiola K, Muroski J, McAllister RA, Yu J, Alvarez AI, Chang C, Ogorzalek Loo RR, Loo JA, Ton-That H, Clubb RT. Kinetics and Optimization of the Lysine-Isopeptide Bond Forming Sortase Enzyme from Corynebacterium diphtheriae. Bioconjug Chem 2020; 31:1624-1634. [PMID: 32396336 PMCID: PMC8153732 DOI: 10.1021/acs.bioconjchem.0c00163] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Site-specifically modified protein bioconjugates have important applications in biology, chemistry, and medicine. Functionalizing specific protein side chains with enzymes using mild reaction conditions is of significant interest, but remains challenging. Recently, the lysine-isopeptide bond forming activity of the sortase enzyme that builds surface pili in Corynebacterium diphtheriae (CdSrtA) has been reconstituted in vitro. A mutationally activated form of CdSrtA was shown to be a promising bioconjugating enzyme that can attach Leu-Pro-Leu-Thr-Gly peptide fluorophores to a specific lysine residue within the N-terminal domain of the SpaA protein (NSpaA), enabling the labeling of target proteins that are fused to NSpaA. Here we present a detailed analysis of the CdSrtA catalyzed protein labeling reaction. We show that the first step in catalysis is rate limiting, which is the formation of the CdSrtA-peptide thioacyl intermediate that subsequently reacts with a lysine ε-amine in NSpaA. This intermediate is surprisingly stable, limiting spurious proteolysis of the peptide substrate. We report the discovery of a new enzyme variant (CdSrtAΔ) that has significantly improved transpeptidation activity, because it completely lacks an inhibitory polypeptide appendage ("lid") that normally masks the active site. We show that the presence of the lid primarily impairs formation of the thioacyl intermediate and not the recognition of the NSpaA substrate. Quantitative measurements reveal that CdSrtAΔ generates its cross-linked product with a catalytic turnover number of 1.4 ± 0.004 h-1 and that it has apparent KM values of 0.16 ± 0.04 and 1.6 ± 0.3 mM for its NSpaA and peptide substrates, respectively. CdSrtAΔ is 7-fold more active than previously studied variants, labeling >90% of NSpaA with peptide within 6 h. The results of this study further improve the utility of CdSrtA as a protein labeling tool and provide insight into the enzyme catalyzed reaction that underpins protein labeling and pilus biogenesis.
Collapse
Affiliation(s)
- Christopher K. Sue
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Scott A. McConnell
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Ken Ellis-Guardiola
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - John Muroski
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Rachel A. McAllister
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Justin Yu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Ana I. Alvarez
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Chungyu Chang
- Molecular Biology Institute and the University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Rachel R. Ogorzalek Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Joseph A. Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- Molecular Biology Institute and the University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Hung Ton-That
- Molecular Biology Institute and the University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| | - Robert T. Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
- Molecular Biology Institute and the University of California, Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095
| |
Collapse
|