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Akbari MS, Joyce LR, Spencer BL, McIver KS, Doran KS. Identification of Glyoxalase A in Group B Streptococcus and its contribution to methylglyoxal tolerance and virulence. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605887. [PMID: 39131367 PMCID: PMC11312555 DOI: 10.1101/2024.07.30.605887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Group B Streptococcus (GBS) is a Gram-positive pathobiont that commonly colonizes the gastrointestinal and lower female genital tracts but can cause sepsis and pneumonia in newborns and is a leading cause of neonatal meningitis. Despite the resulting disease severity, the pathogenesis of GBS is not completely understood, especially during the early phases of infection. To investigate GBS factors necessary for blood stream survival, we performed a transposon (Tn) mutant screen in our bacteremia infection model using a GBS mariner transposon mutant library previously developed by our group. We identified significantly underrepresented mutations in 628 genes that contribute to survival in the blood, including those encoding known virulence factors such as capsule, the β-hemolysin, and inorganic metal ion transport systems. Most of the underrepresented genes have not been previously characterized or studied in GBS, including gloA and gloB, which are homologs for genes involved in methylglyoxal (MG) detoxification. MG is a byproduct of glycolysis and a highly reactive toxic aldehyde that is elevated in immune cells during infection. Here, we observed MG sensitivity across multiple GBS isolates and confirm that gloA contributes to MG tolerance and invasive GBS infection. We show specifically that gloA contributes to GBS survival in the presence of neutrophils and depleting neutrophils in mice abrogates the decreased survival and infection of the gloA mutant. The requirement of the glyoxalase pathway during GBS infection suggests that MG detoxification is important for bacterial survival during host-pathogen interactions.
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Affiliation(s)
- Madeline S. Akbari
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado USA
| | - Luke R. Joyce
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado USA
| | - Brady L. Spencer
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado USA
| | - Kevin S. McIver
- Cell Biology and Molecular Genetics, Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Kelly S. Doran
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado USA
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Vollmuth N, Bridgers BE, Armstrong ML, Wood JF, Gildea AR, Espinal ER, Hooven TA, Barbieri G, Westermann AJ, Sauerwein T, Foerstner KU, Schubert-Unkmeir A, Kim BJ. Group B Streptococcus transcriptome when interacting with brain endothelial cells. J Bacteriol 2024; 206:e0008724. [PMID: 38771039 PMCID: PMC11332166 DOI: 10.1128/jb.00087-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 04/22/2024] [Indexed: 05/22/2024] Open
Abstract
Bacterial meningitis is a life-threatening infection of the central nervous system (CNS) that occurs when bacteria are able to cross the blood-brain barrier (BBB) or the meningeal-cerebrospinal fluid barrier (mBCSFB). The BBB and mBCSFB comprise highly specialized brain endothelial cells (BECs) that typically restrict pathogen entry. Group B Streptococcus (GBS or Streptococcus agalactiae) is the leading cause of neonatal meningitis. Until recently, identification of GBS virulence factors has relied on genetic screening approaches. Instead, we here conducted RNA-seq analysis on GBS when interacting with induced pluripotent stem cell-derived BECs (iBECs) to pinpoint virulence-associated genes. Of the 2,068 annotated protein-coding genes of GBS, 430 transcripts displayed significant changes in expression after interacting with BECs. Notably, we found that the majority of differentially expressed GBS transcripts were downregulated (360 genes) during infection of iBECs. Interestingly, codY, encoding a pleiotropic transcriptional repressor in low-G + C Gram-positive bacteria, was identified as being highly downregulated. We conducted qPCR to confirm the codY downregulation observed via RNA-seq during the GBS-iBEC interaction and obtained codY mutants in three different GBS background parental strains. As anticipated from the RNA-seq results, the [Formula: see text]codY strains were more adherent and invasive in two in vitro BEC models. Together, this demonstrates the utility of RNA-seq during the BEC interaction to identify GBS virulence modulators. IMPORTANCE Group B Streptococcus (GBS) meningitis remains the leading cause of neonatal meningitis. Research work has identified surface factors and two-component systems that contribute to GBS disruption of the blood-brain barrier (BBB). These discoveries often relied on genetic screening approaches. Here, we provide transcriptomic data describing how GBS changes its transcriptome when interacting with brain endothelial cells. Additionally, we have phenotypically validated these data by obtaining mutants of a select regulator that is highly down-regulated during infection and testing on our BBB model. This work provides the research field with a validated data set that can provide an insight into potential pathways that GBS requires to interact with the BBB and open the door to new discoveries.
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Affiliation(s)
- Nadine Vollmuth
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Bailey E. Bridgers
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Madelyn L. Armstrong
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Jacob F. Wood
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Abigail R. Gildea
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Eric R. Espinal
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Thomas A. Hooven
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Richard King Mellon Institute for Pediatric Research, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Giulia Barbieri
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Alexander J. Westermann
- Institute of Molecular Infection Biology (IMIB), University of Wuerzburg, Wuerzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Wuerzburg, Germany
| | - Till Sauerwein
- Institute of Molecular Infection Biology (IMIB), University of Wuerzburg, Wuerzburg, Germany
- ZB MED, Information Centre for Life Sciences, Cologne, Germany
| | - Konrad U. Foerstner
- Institute of Molecular Infection Biology (IMIB), University of Wuerzburg, Wuerzburg, Germany
- ZB MED, Information Centre for Life Sciences, Cologne, Germany
- TH Koeln, University of Applied Sciences, Cologne, Germany
| | | | - Brandon J. Kim
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
- Department of Microbiology, University of Alabama at Birmingham Heesink School of Medicine, Birmingham, Alabama, USA
- University of Alabama Center of Convergent Biosciences and Medicine, Tuscaloosa, Alabama, USA
- University of Alabama Life Research, Tuscaloosa, Alabama, USA
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Joyce LR, Kim S, Spencer BL, Christensen PM, Palmer KL, Guan Z, Siegenthaler JA, Doran KS. Streptococcus agalactiae glycolipids promote virulence by thwarting immune cell clearance. SCIENCE ADVANCES 2024; 10:eadn7848. [PMID: 38809989 PMCID: PMC11135403 DOI: 10.1126/sciadv.adn7848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 04/25/2024] [Indexed: 05/31/2024]
Abstract
Streptococcus agalactiae [group B Streptococcus (GBS)] is a leading cause of neonatal meningitis, with late-onset disease (LOD) occurring after gastrointestinal tract colonization in infants. Bacterial membrane lipids are essential for host-pathogen interactions, and the functions of glycolipids are yet to be fully elucidated. GBS synthesizes three major glycolipids: glucosyl-diacylglycerol (Glc-DAG), diglucosyl-DAG (Glc2-DAG), and lysyl-Glc-DAG (Lys-Glc-DAG). Here, we identify the enzyme, IagB, as responsible for biosynthesis of Glc-DAG, the precursor for the two other glycolipids in GBS. To examine the collective role of glycolipids to GBS virulence, we adapted a murine model of neonatal meningitis to simulate LOD. The GBS∆iagB mutant traversed the gut-epithelial barrier comparable to wild type but was severely attenuated in bloodstream survival, resulting in decreased bacterial loads in the brain. The GBS∆iagB mutant was more susceptible to neutrophil killing and membrane targeting by host antimicrobial peptides. This work reveals an unexplored function of GBS glycolipids with their ability to protect the bacterial cell from host antimicrobial killing.
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Affiliation(s)
- Luke R. Joyce
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Sol Kim
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Brady L. Spencer
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Priya M. Christensen
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Julie A. Siegenthaler
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Kelly S. Doran
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA
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Wood PL, Erol E. Construction of a Bacterial Lipidomics Analytical Platform: Pilot Validation with Bovine Paratuberculosis Serum. Metabolites 2023; 13:809. [PMID: 37512516 PMCID: PMC10383236 DOI: 10.3390/metabo13070809] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/23/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Lipidomics analyses of bacteria offer the potential to detect and monitor infections in a host since many bacterial lipids are not present in mammals. To evaluate this omics approach, we first built a database of bacterial lipids for representative Gram-positive and Gram-negative bacteria. Our lipidomics analysis of the reference bacteria involved high-resolution mass spectrometry and electrospray ionization with less than a 1.0 ppm mass error. The lipidomics profiles of bacterial cultures clearly distinguished between Gram-positive and Gram-negative bacteria. In the case of bovine paratuberculosis (PTB) serum, we monitored two unique bacterial lipids that we also monitored in Mycobacterium avian subspecies PTB. These were PDIM-B C82, a phthiodiolone dimycocerosate, and the trehalose monomycolate hTMM 28:1, constituents of the bacterial cell envelope in mycolic-containing bacteria. The next step will be to determine if lipidomics can detect subclinical PTB infections which can last 2-to-4 years in bovine PTB. Our data further suggest that it will be worthwhile to continue building our bacterial lipidomics database and investigate the further utility of this approach in other infections of veterinary and human clinical interest.
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Affiliation(s)
- Paul L Wood
- Metabolomics Unit, College of Veterinary Medicine, Lincoln Memorial University, 6965 Cumberland Gap Pkwy, Harrogate, TN 37752, USA
| | - Erdal Erol
- Department of Veterinary Science, Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY 40546, USA
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Zeng X, Hinenoya A, Guan Z, Xu F, Lin J. Critical role of the RpoE stress response pathway in polymyxin resistance of Escherichia coli. J Antimicrob Chemother 2023; 78:732-746. [PMID: 36658759 PMCID: PMC10396327 DOI: 10.1093/jac/dkad003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 12/31/2022] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVES Polymyxins, including colistin, are the drugs of last resort to treat MDR bacterial infections in humans. In-depth understanding of the molecular basis and regulation of polymyxin resistance would provide new therapeutic opportunities to combat increasing polymyxin resistance. Here we aimed to identify novel targets that are crucial for polymyxin resistance using Escherichia coli BL21(DE3), a unique colistin-resistant model strain. METHODS BL21(DE3) was subjected to random transposon mutagenesis for screening colistin-susceptible mutants. The insertion sites of desired mutants were mapped; the key genes of interest were also inactivated in different strains to examine functional conservation. Specific genes in the known PmrAB and PhoPQ regulatory network were inactivated to examine crosstalk among different pathways. Lipid A species and membrane phospholipids were analysed by normal phase LC/MS. RESULTS Among eight mutants with increased susceptibility to colistin, five mutants contained different mutations in three genes (rseP, degS and surA) that belong to the RpoE stress response pathway. Inactivation of rpoE, pmrB, eptA or pmrD led to significantly increased susceptibility to colistin; however, inactivation of phoQ or eptB did not change colistin MIC. RpoE mutation in different E. coli and Salmonella resistant strains all led to significant reduction in colistin MIC (16-32-fold). Inactivation of rpoE did not change the lipid A profile but significantly altered the phospholipid profile. CONCLUSIONS Inactivation of the important members of the RpoE regulon in polymyxin-resistant strains led to a drastic reduction in polymyxin MIC and an increase of lysophospholipids with no change in lipid A modifications.
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Affiliation(s)
- Ximin Zeng
- Department of Animal Science, The University of Tennessee, Knoxville, TN, USA
| | - Atsushi Hinenoya
- Department of Animal Science, The University of Tennessee, Knoxville, TN, USA
- Graduate School of Veterinary Science, Osaka Metropolitan University, Osaka, Japan
- Asian Health Science Research Institute, Osaka Metropolitan University, Osaka, Japan
- Osaka International Research Center for Infectious Diseases, Osaka Metropolitan University, Osaka, Japan
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Fuzhou Xu
- Department of Animal Science, The University of Tennessee, Knoxville, TN, USA
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Jun Lin
- Department of Animal Science, The University of Tennessee, Knoxville, TN, USA
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Abstract
Gram-positive bacterial cells are protected from the environment by a cell envelope that is comprised of a thick layer of peptidoglycan that maintains cell shape and teichoic acid polymers whose biological function remains unclear. In Bacillus subtilis, the loss of all class A penicillin-binding proteins (aPBPs), which function in peptidoglycan synthesis, is conditionally lethal. Here, we show that this lethality is associated with an alteration of lipoteichoic acids (LTAs) and the accumulation of the major autolysin LytE in the cell wall. Our analysis provides further evidence that the length and abundance of LTAs act to regulate the cellular level and activity of autolytic enzymes, specifically LytE. Importantly, we identify a novel function for the aminoacyl-phosphatidylglycerol synthase MprF in the modulation of LTA biosynthesis in both B. subtilis and Staphylococcus aureus. This finding has implications for our understanding of antimicrobial resistance (particularly to daptomycin) in clinically relevant bacteria and the involvement of MprF in the virulence of pathogens such as methicillin-resistant S. aureus (MRSA). IMPORTANCE In Gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus, the cell envelope is a structure that protects the cells from the environment but is also dynamic in that it must be modified in a controlled way to allow cell growth. In this study, we show that lipoteichoic acids (LTAs), which are anionic polymers attached to the membrane, have a direct role in modulating the cellular abundance of cell wall-degrading enzymes. We also find that the apparent length of the LTA is modulated by the activity of the enzyme MprF, previously implicated in modifications of the cell membrane leading to resistance to antimicrobial peptides. These findings are important contributions to our understanding of how bacteria balance cell wall synthesis and degradation to permit controlled growth and division. These results also have implications for the interpretation of antibiotic resistance, particularly for the clinical treatment of MRSA infections.
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Gram-positive bacterial membrane lipids at the host-pathogen interface. PLoS Pathog 2023; 19:e1011026. [PMID: 36602959 DOI: 10.1371/journal.ppat.1011026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Structural Identification of Lipid-α: A Glycosyl Lipid Involved in Oligo- And Polysaccharides Metabolism in Streptococcus agalactiae (Group B Streptococcus). Curr Microbiol 2022; 80:16. [PMID: 36459236 DOI: 10.1007/s00284-022-03117-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 11/09/2022] [Indexed: 12/04/2022]
Abstract
Streptococcus agalactiae (group B Streptococcus, GBS) is a gram-positive bacterium that is an asymptomatic colonizer commonly found in the gastrointestinal and genitourinary tract of healthy adults. GBS is also the most common cause of life-threatening bacterial infections in newborns and is emerging as a pathogen in immunocompromised and diabetic adults. The GBS cell wall and covalently linked capsular polysaccharides (CPS) are vital to the protection of the bacterial cell and act as virulence factors. GBS-CPS have been successfully used to produce conjugate vaccines for all currently identified GBS serotypes. However, the mechanisms of biosynthesis and assembly of CPS and the other cell wall components remain poorly defined due to their complex surface structures. In this biosynthetic study of the GBS cell wall-CPS complex, glycolipids with varying lengths of glycosyl-chains were discovered. Among those, one of the smallest glycolipids (named GBS Lipid-α) was structurally characterized. Lipid-α is involved in GBS saccharide metabolism and presumably acts as a glycosyl acceptor to elongate the glycosyl chain. GBS Lipid-α was determined to be a 3-monosaccharide 1,2 acyl glycerol with a molecular mass in the range of m/z = 724-808. GBS Lipid-α is highly heterogenic with various acyl groups and glycosyl moieties. This knowledge will pave the way for future studies to elucidate the entire metabolic pathway and genes involved. The Lipid-α pathway may also exist in other bacterial species and has the potential to be a biomarker for future drug development.
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Ren Z, Chhetri A, Guan Z, Suo Y, Yokoyama K, Lee SY. Structural basis for inhibition and regulation of a chitin synthase from Candida albicans. Nat Struct Mol Biol 2022; 29:653-664. [PMID: 35788183 DOI: 10.1038/s41594-022-00791-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 05/20/2022] [Indexed: 11/09/2022]
Abstract
Chitin is an essential component of the fungal cell wall. Chitin synthases (Chss) catalyze chitin formation and translocation across the membrane and are targets of antifungal agents, including nikkomycin Z and polyoxin D. Lack of structural insights into the action of these inhibitors on Chs has hampered their further development to the clinic. We present the cryo-EM structures of Chs2 from Candida albicans (CaChs2) in the apo, substrate-bound, nikkomycin Z-bound, and polyoxin D-bound states. CaChs2 adopts a unique domain-swapped dimer configuration where a conserved motif in the domain-swapped region controls enzyme activity. CaChs2 has a dual regulation mechanism where the chitin translocation tunnel is closed by the extracellular gate and plugged by a lipid molecule in the apo state to prevent non-specific leak. Analyses of substrate and inhibitor binding provide insights into the chemical logic of Chs inhibition, which can guide Chs-targeted antifungal development.
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Affiliation(s)
- Zhenning Ren
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Abhishek Chhetri
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Yang Suo
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Kenichi Yokoyama
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
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