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Raghunandanan S, Zhang K, Zhang Y, Sze CW, Priya R, Luo Y, Lynch MJ, Crane BR, Li C, Yang XF. MCP5, a methyl-accepting chemotaxis protein regulated by both the Hk1-Rrp1 and Rrp2-RpoN-RpoS pathways, is required for the immune evasion of Borrelia burgdorferi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.598185. [PMID: 38915556 PMCID: PMC11195095 DOI: 10.1101/2024.06.10.598185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Borrelia (or Borreliella) burgdorferi, the causative agent of Lyme disease, is a motile and invasive zoonotic pathogen, adept at navigating between its arthropod vector and mammalian host. While motility and chemotaxis are well established as essential for its enzootic cycle, the function of methyl-accepting chemotaxis proteins (MCPs) in the infectious cycle of B. burgdorferi remains unclear. In this study, we demonstrate that MCP5, one of the most abundant MCPs in B. burgdorferi, is differentially expressed in response to environmental signals as well as at different stages of the pathogen's enzootic cycle. Specifically, the expression of mcp5 is regulated by the Hk1-Rrp1 and Rrp2-RpoN-RpoS pathways, which are critical for the spirochete's colonization of the tick vector and mammalian host, respectively. Infection experiments with an mcp5 mutant revealed that spirochetes lacking MCP5 could not establish infections in either C3H/HeN mice or Severe Combined Immunodeficiency (SCID) mice, which are defective in adaptive immunity, indicating the essential role of MCP5 in mammalian infection. However, the mcp5 mutant could establish infection and disseminate in NOD SCID Gamma (NSG) mice, which are deficient in both adaptive and most innate immune responses, suggesting a crucial role of MCP5 in evading host innate immunity. In the tick vector, the mcp5 mutants survived feeding but failed to transmit to mice, highlighting the importance of MCP5 in transmission. Our findings reveal that MCP5, regulated by the Rrp1 and Rrp2 pathways, is critical for the establishment of infection in mammalian hosts by evading host innate immunity and is important for the transmission of spirochetes from ticks to mammalian hosts, underscoring its potential as a target for intervention strategies.
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Affiliation(s)
- Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Kai Zhang
- Department of Oral Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - Yan Zhang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China, 325035
| | - Ching Wooen Sze
- Department of Oral Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - Raj Priya
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Yongliang Luo
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China, 325035
| | - Michael J Lynch
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Chunhao Li
- Department of Oral Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
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Raghunandanan S, Priya R, Alanazi F, Lybecker MC, Schlax P, Yang X. A Fur family protein BosR is a novel RNA-binding protein that controls rpoS RNA stability in the Lyme disease pathogen. Nucleic Acids Res 2024; 52:5320-5335. [PMID: 38366569 PMCID: PMC11109971 DOI: 10.1093/nar/gkae114] [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: 10/13/2023] [Revised: 02/01/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
The σ54-σS sigma factor cascade plays a central role in regulating differential gene expression during the enzootic cycle of Borreliella burgdorferi, the Lyme disease pathogen. In this pathway, the primary transcription of rpoS (which encodes σS) is under the control of σ54 which is activated by a bacterial enhancer-binding protein (EBP), Rrp2. The σ54-dependent activation in B. burgdorferi has long been thought to be unique, requiring an additional factor, BosR, a homologue of classical Fur/PerR repressor/activator. However, how BosR is involved in this σ54-dependent activation remains unclear and perplexing. In this study, we demonstrate that BosR does not function as a regulator for rpoS transcriptional activation. Instead, it functions as a novel RNA-binding protein that governs the turnover rate of rpoS mRNA. We further show that BosR directly binds to the 5' untranslated region (UTR) of rpoS mRNA, and the binding region overlaps with a region required for rpoS mRNA degradation. Mutations within this 5'UTR region result in BosR-independent RpoS production. Collectively, these results uncover a novel role of Fur/PerR family regulators as RNA-binding proteins and redefine the paradigm of the σ54-σS pathway in B. burgdorferi.
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Affiliation(s)
- Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Raj Priya
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Fuad Alanazi
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 12372, Saudi Arabia
| | - Meghan C Lybecker
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Center for Disease Control and Prevention, Fort Collins, CO, USA
| | - Paula Jean Schlax
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - X Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Yaş OB, Coleman AS, Lipman RM, Sharma K, Raghunandanan S, Alanazi F, Rana VS, Kitsou C, Yang X, Pal U. A systemic approach to identify non-abundant immunogenic proteins in Lyme disease pathogens. mSystems 2024; 9:e0108723. [PMID: 38078774 PMCID: PMC10805064 DOI: 10.1128/msystems.01087-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/06/2023] [Indexed: 01/24/2024] Open
Abstract
Borrelia burgdorferi, the pathogen of Lyme disease, differentially produces many outer surface proteins (Osp), some of which represent the most abundant membrane proteins, such as OspA, OspB, and OspC. In cultured bacteria, these proteins can account for a substantial fraction of the total cellular or membrane proteins, posing challenges to the identification and analysis of non-abundant proteins, which could serve as novel pathogen detection markers or as vaccine candidates. Herein, we introduced serial mutations to remove these abundant Osps and generated a B. burgdorferi mutant deficient in OspA, OspB, and OspC in an infectious 297-isolate background, designated as OspABC- mutant. Compared to parental isolate, the mutant did not reflect growth defects in the cultured medium but showed differential mRNA expression of representative tested genes, in addition to gross changes in cellular and membrane protein profiles. The analysis of differentially detectable protein contents of the OspABC- mutant, as compared to the wild type, by two-dimensional gel electrophoresis followed by liquid chromatography-mass spectrometry, identified several spirochete proteins that are dominated by proteins of unknown functions, as well as membrane transporters, chaperons, and metabolic enzymes. We produced recombinant forms of two of these represented proteins, BBA34 and BB0238, and showed that these proteins are detectable during spirochete infection in the tick-borne murine model of Lyme borreliosis and thus serve as potential antigenic markers of the infection.IMPORTANCEThe present manuscript employed a systemic approach to identify non-abundant proteins in cultured Borrelia burgdorferi that are otherwise masked or hidden due to the overwhelming presence of abundant Osps like OspA, OspB, and OspC. As these Osps are either absent or transiently expressed in mammals, we performed a proof-of-concept study in which their removal allowed the analysis of otherwise less abundant antigens in OspABC-deficient mutants and identified several immunogenic proteins, including BBA34 and BB0238. These antigens could serve as novel vaccine candidates and/or genetic markers of Lyme borreliosis, promoting new research in the clinical diagnosis and prevention of Lyme disease.
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Affiliation(s)
- Ozlem Buyuktanir Yaş
- Department of Microbiology, Faculty of Veterinary Medicine, Ondokuz Mayis University, Samsun, Turkey
| | - Adam S. Coleman
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Rachel M. Lipman
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Kavita Sharma
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Fuad Alanazi
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Vipin S. Rana
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Chrysoula Kitsou
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Xiuli Yang
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Utpal Pal
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
- Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
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Sze CW, Zhang K, Lynch MJ, Iyer R, Crane BR, Schwartz I, Li C. A chemosensory-like histidine kinase is dispensable for chemotaxis in vitro but regulates the virulence of Borrelia burgdorferi through modulating the stability of RpoS. PLoS Pathog 2023; 19:e1011752. [PMID: 38011206 PMCID: PMC10703414 DOI: 10.1371/journal.ppat.1011752] [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: 08/10/2023] [Revised: 12/07/2023] [Accepted: 10/14/2023] [Indexed: 11/29/2023] Open
Abstract
As an enzootic pathogen, the Lyme disease bacterium Borrelia burgdorferi possesses multiple copies of chemotaxis proteins, including two chemotaxis histidine kinases (CHK), CheA1 and CheA2. Our previous study showed that CheA2 is a genuine CHK that is required for chemotaxis; however, the role of CheA1 remains mysterious. This report first compares the structural features that differentiate CheA1 and CheA2 and then provides evidence to show that CheA1 is an atypical CHK that controls the virulence of B. burgdorferi through modulating the stability of RpoS, a key transcriptional regulator of the spirochete. First, microscopic analyses using green-fluorescence-protein (GFP) tags reveal that CheA1 has a unique and dynamic cellular localization. Second, loss-of-function studies indicate that CheA1 is not required for chemotaxis in vitro despite sharing a high sequence and structural similarity to its counterparts from other bacteria. Third, mouse infection studies using needle inoculations show that a deletion mutant of CheA1 (cheA1mut) is able to establish systemic infection in immune-deficient mice but fails to do so in immune-competent mice albeit the mutant can survive at the inoculation site for up to 28 days. Tick and mouse infection studies further demonstrate that CheA1 is dispensable for tick colonization and acquisition but essential for tick transmission. Lastly, mechanistic studies combining immunoblotting, protein turnover, mutagenesis, and RNA-seq analyses reveal that depletion of CheA1 affects RpoS stability, leading to reduced expression of several RpoS-regulated virulence factors (i.e., OspC, BBK32, and DbpA), likely due to dysregulated clpX and lon protease expression. Bulk RNA-seq analysis of infected mouse skin tissues further show that cheA1mut fails to elicit mouse tnf-α, il-10, il-1β, and ccl2 expression, four important cytokines for Lyme disease development and B. burgdorferi transmigration. Collectively, these results reveal a unique role and regulatory mechanism of CheA1 in modulating virulence factor expression and add new insights into understanding the regulatory network of B. burgdorferi.
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Affiliation(s)
- Ching Wooen Sze
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Kai Zhang
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Michael J. Lynch
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Radha Iyer
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, United States of America
| | - Brian R. Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Ira Schwartz
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, United States of America
| | - Chunhao Li
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, United States of America
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Stevenson B. The Lyme disease spirochete, Borrelia burgdorferi, as a model vector-borne pathogen: insights on regulation of gene and protein expression. Curr Opin Microbiol 2023; 74:102332. [PMID: 37279610 PMCID: PMC10524203 DOI: 10.1016/j.mib.2023.102332] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 04/26/2023] [Accepted: 05/03/2023] [Indexed: 06/08/2023]
Abstract
The Lyme disease spirochete persists in nature through cycles between ticks and vertebrates. Although the spirochete interacts with numerous, distinct tissues and environmental conditions during its infectious cycle, Borrelia burgdorferi appears to possess a limited ability to sense its external environment. This apparent paradox is being resolved through detailed investigations of the molecular mechanisms through which B. burgdorferi controls production of virulence-associated factors such as the Erp outer surface proteins. The results have led to development of a model for how B. burgdorferi controls expression of its diverse proteins, wherein physiological and metabolic states that are unique to specific points in the infectious cycle trigger changes in gene and protein expression levels.
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Affiliation(s)
- Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA; Department of Entomology, University of Kentucky, Lexington, KY, USA.
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Sze CW, Li C. Chemotaxis Coupling Protein CheW 2 Is Not Required for the Chemotaxis but Contributes to the Full Pathogenicity of Borreliella burgdorferi. Infect Immun 2023; 91:e0000823. [PMID: 36939335 PMCID: PMC10112267 DOI: 10.1128/iai.00008-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/23/2023] [Indexed: 03/21/2023] Open
Abstract
The bacterial chemotaxis regulatory circuit mainly consists of coupling protein CheW, sensor histidine kinase CheA, and response regulator CheY. Most bacteria, such as Escherichia coli, have a single gene encoding each of these proteins. Interestingly, the Lyme disease pathogen, Borreliella burgdorferi, has multiple chemotaxis proteins, e.g., two CheA, three CheW, and three CheY proteins. The genes encoding these proteins mainly reside in two operons: cheW2-cheA1-cheB2-cheY2 (A-I) and cheA2-cheW3-cheX-cheY3 (A-II). Previous studies demonstrate that all the genes in A-II are essential for the chemotaxis of B. burgdorferi; however, the role of those genes in A-I remains unknown. This study aimed to fill this gap using the CheW2 gene, the first gene in A-I, as a surrogate. We first mapped the transcription start site of A-I upstream of cheW2 and identified a σ70-like promoter (PW2) and two binding sites (BS1 and BS2) of BosR, an unorthodox Fur/Per homolog. We then demonstrated that BosR binds to PW2 via BS1 and BS2 and that deletion of bosR significantly represses the expression of cheW2 and other genes in A-I, implying that BosR is a positive regulator of A-I. Deletion of cheW2 has no impact on the chemotaxis of B. burgdorferi in vitro but abrogates its ability to evade host adaptive immunity, because the mutant can establish systemic infection only in SCID mice and not in immunocompetent BALB/c mice. This report substantiates the previous proposition that A-I is not implicated in chemotaxis; rather, it may function as a signaling transduction pathway to regulate B. burgdorferi virulence gene expression.
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Affiliation(s)
- Ching Wooen Sze
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Chunhao Li
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA
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Rana VS, Kitsou C, Dumler JS, Pal U. Immune evasion strategies of major tick-transmitted bacterial pathogens. Trends Microbiol 2023; 31:62-75. [PMID: 36055896 PMCID: PMC9772108 DOI: 10.1016/j.tim.2022.08.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/28/2022] [Accepted: 08/01/2022] [Indexed: 12/30/2022]
Abstract
Tick-transmitted bacterial pathogens thrive in enzootic infection cycles, colonizing disparate vertebrate and arthropod tissues, often establishing persistent infections. Therefore, the evolution of robust immune evasion strategies is central to their successful persistence or transmission between hosts. To survive in nature, these pathogens must counteract a broad range of microbicidal host responses that can be localized, tissue-specific, or systemic, including a mix of these responses at the host-vector interface. Herein, we review microbial immune evasion strategies focusing on Lyme disease spirochetes and rickettsial or tularemia agents as models for extracellular and intracellular tick-borne pathogens, respectively. A better understanding of these adaptive strategies could enrich our knowledge of the infection biology of relevant tick-borne diseases, contributing to the development of future preventions.
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Affiliation(s)
- Vipin Singh Rana
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Chrysoula Kitsou
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - J Stephen Dumler
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Utpal Pal
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA.
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Li L, Di L, Akther S, Zeglis BM, Qiu W. Evolution of the vls Antigenic Variability Locus of the Lyme Disease Pathogen and Development of Recombinant Monoclonal Antibodies Targeting Conserved VlsE Epitopes. Microbiol Spectr 2022; 10:e0174322. [PMID: 36150043 PMCID: PMC9604149 DOI: 10.1128/spectrum.01743-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/02/2022] [Indexed: 01/12/2023] Open
Abstract
VlsE (variable major protein-like sequence, expressed) is an outer surface protein of the Lyme disease pathogen (Borreliella species) responsible for its within-host antigenic variation and a key diagnostic biomarker of Lyme disease. However, the high sequence variability of VlsE poses a challenge to the development of consistent VlsE-based diagnostics and therapeutics. In addition, the standard diagnostic protocols detect immunoglobins elicited by the Lyme pathogen, not the presence of the pathogen or its derived antigens. Here, we described the development of recombinant monoclonal antibodies (rMAbs) that bound specifically to conserved epitopes on VlsE. We first quantified amino-acid sequence variability encoded by the vls genes from 13 B. burgdorferi genomes by evolutionary analyses. We showed broad inconsistencies of the sequence phylogeny with the genome phylogeny, indicating rapid gene duplications, losses, and recombination at the vls locus. To identify conserved epitopes, we synthesized peptides representing five long conserved invariant regions (IRs) on VlsE. We tested the antigenicity of these five IR peptides using sera from three mammalian host species including human patients, the natural reservoir white-footed mouse (Peromyscus leucopus), and VlsE-immunized New Zealand rabbits (Oryctolagus cuniculus). The IR4 and IR6 peptides emerged as the most antigenic and reacted strongly with both the human and rabbit sera, while all IR peptides reacted poorly with sera from natural hosts. Four rMAbs binding specifically to the IR4 and IR6 peptides were identified, cloned, and purified. Given their specific recognition of the conserved epitopes on VlsE, these IR-specific rMAbs are potential novel diagnostic and research agents for direct detection of Lyme disease pathogens regardless of strain heterogeneity. IMPORTANCE Current diagnostic protocols of Lyme disease indirectly detect the presence of antibodies produced by the patient upon infection by the bacterial pathogen, not the pathogen itself. These diagnostic tests tend to underestimate early-stage bacterial infections before the patients develop robust immune responses. Further, the indirect tests do not distinguish between active or past infections by the Lyme disease bacteria in a patient sample. Here, we described novel monoclonal antibodies that have the potential to become the basis of direct and definitive diagnostic detection of the Lyme disease pathogen, regardless of its genetic heterogeneity.
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Affiliation(s)
- Li Li
- Graduate Center, City University of New York, New York, New York, USA
| | - Lia Di
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA
| | - Saymon Akther
- Graduate Center, City University of New York, New York, New York, USA
| | - Brian M. Zeglis
- Graduate Center, City University of New York, New York, New York, USA
- Department of Chemistry, Hunter College, City University of New York, New York, New York, USA
- Department of Radiology, Weill Cornell Medical College, New York, New York, USA
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Weigang Qiu
- Graduate Center, City University of New York, New York, New York, USA
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, USA
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, USA
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Identification and Characterization of the Alternative σ 28 Factor in Treponema denticola. J Bacteriol 2022; 204:e0024822. [PMID: 36043861 PMCID: PMC9487585 DOI: 10.1128/jb.00248-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FliA (also known as σ28), a member of the bacterial σ70 family of transcription factors, directs RNA polymerase to flagellar late (class 3) promoters and initiates transcription. FliA has been studied in several bacteria, yet its role in spirochetes has not been established. In this report, we identify and functionally characterize a FliA homolog (TDE2683) in the oral spirochete Treponema denticola. Computational, genetic, and biochemical analyses demonstrated that TDE2683 has a structure similar to that of the σ28 of Escherichia coli, binds to σ28-dependent promoters, and can functionally replace the σ28 of E. coli. However, unlike its counterparts from other bacteria, TDE2683 cannot be deleted, suggesting its essential role in the survival of T. denticola. In vitro site-directed mutagenesis revealed that E221 and V231, two conserved residues in the σ4 region of σ28, are indispensable for the binding activity of TDE2683 to the σ28-dependent promoter. We then mutated these two residues in T. denticola and found that the mutations impair the expression of flagellin and chemotaxis genes and bacterial motility as well. Cryo-electron tomography analysis further revealed that the mutations disrupt the flagellar symmetry (i.e., number and placement) of T. denticola. Collectively, these results indicate that TDE2683 is a σ28 transcription factor that regulates the class 3 gene expression and controls the flagellar symmetry of T. denticola. To the best of our knowledge, this is the first report establishing the functionality of FliA in spirochetes. IMPORTANCE Spirochetes are a group of medically important but understudied bacteria. One of the unique aspects of spirochetes is that they have periplasmic flagella (PF, also known as endoflagella) which give rise to their unique spiral shape and distinct swimming behaviors and play a critical role in the pathophysiology of spirochetes. PF are structurally similar to external flagella, but the underpinning mechanism that regulates PF biosynthesis and assembly remains largely unknown. By using the oral spirochete Treponema denticola as a model, this report provides several lines of evidence that FliA, a σ28 transcriptional factor, regulates the late flagellin gene (class 3) expression, PF assembly, and flagellar symmetry as well, which provides insights into flagellar regulation and opens an avenue to investigate the role of σ28 in spirochetes.
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Król N, Obiegala A, Imholt C, Arz C, Schmidt E, Jeske K, Ulrich RG, Rentería-Solís Z, Jacob J, Pfeffer M. Diversity of Borrelia burgdorferi sensu lato in ticks and small mammals from different habitats. Parasit Vectors 2022; 15:195. [PMID: 35672762 PMCID: PMC9175456 DOI: 10.1186/s13071-022-05326-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/16/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ixodid ticks are important vectors for zoonotic pathogens, with Ixodes ricinus being the most important in Europe. Rodents are hosts of immature life stages of I. ricinus ticks and are considered main reservoirs for tick-borne pathogens, e.g. Borrelia burgdorferi. The aim of this study was to analyse the prevalence as well as genospecies and sequence type (ST) diversity of Borrelia burgdorferi sensu lato in ticks and small mammals from central Germany and to elaborate on the influence of environmental and/or individual host and vector factors on Borrelia prevalence. METHODS After species identification, 1167 small mammal skin samples and 1094 ticks from vegetation were screened by B. burgdorferi sensu lato real-time polymerase chain reaction, and positive samples were characterized by multilocus sequence typing. Generalized linear (mixed) models were used to estimate how seasonality, small mammal species/tick life stage and habitat affect individual infection status. RESULTS In total, 10 small mammal species and three tick species, Ixodes ricinus, Ixodes inopinatus (both considered members of the I. ricinus complex) and Dermacentor reticulatus, were investigated. Borrelia DNA was detected in eight host species, i.e. the striped field mouse (Apodemus agrarius), the yellow-necked field mouse (Apodemus flavicollis), the wood mouse (Apodemus sylvaticus), the water vole (Arvicola amphibius), the bank vole (Clethrionomys glareolus), the field vole (Microtus agrestis), the common vole (Microtus arvalis), and the common shrew (Sorex araneus). Two species were Borrelia negative, the greater white-toothed shrew (Crocidura russula) and the pygmy shrew (Sorex minutus). The average prevalence was 6.2%, with two genospecies detected, Borrelia afzelii and Borrelia garinii, and at least three STs that had not been previously reported in small mammals. Borrelia prevalence in small mammals did not differ between seasons. Six genospecies of Borrelia-Borrelia afzelii, Borrelia valaisiana, Borrelia garinii, Borrelia lusitaniae, Borrelia spielmanii, and Borrelia burgdorferi sensu stricto-and 25 STs of Borrelia, of which 12 have not been previously described at all and five have not been previously reported in Germany, were detected in 13% of I. ricinus complex ticks. Prevalence was highest in adult females (25.3%) and lowest in nymphs (11.4%). Prevalence was significantly higher in ticks from grassland (16.8%) compared to forests (11.4%). CONCLUSIONS The high level of small mammal diversity in this region of Germany seems to be reflected in a wide variety of genospecies and STs of B. burgdorferi.
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Affiliation(s)
- Nina Król
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 1, 04103, Leipzig, Germany
| | - Anna Obiegala
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 1, 04103, Leipzig, Germany
| | - Christian Imholt
- Institute for Plant Protection in Horticulture and Forests, Julius Kühn-Institute, Toppheideweg 88, 48161, Münster, Germany
| | - Charlotte Arz
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 1, 04103, Leipzig, Germany
| | - Elisabeth Schmidt
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 1, 04103, Leipzig, Germany
| | - Kathrin Jeske
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Südufer 10, 17493, Greifswald, Insel Riems, Germany
| | - Rainer Günter Ulrich
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Südufer 10, 17493, Greifswald, Insel Riems, Germany
| | - Zaida Rentería-Solís
- Institute for Parasitology, Centre for Infectious Diseases, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 35, 04103, Leipzig, Germany
| | - Jens Jacob
- Institute for Plant Protection in Horticulture and Forests, Julius Kühn-Institute, Toppheideweg 88, 48161, Münster, Germany
| | - Martin Pfeffer
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, An den Tierkliniken 1, 04103, Leipzig, Germany.
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11
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Thompson C, George S, White ML, Eswara PJ, Ouyang Z. BB0761, a MepM homolog, contributes to Borrelia burgdorferi cell division and mammalian infectivity. Mol Microbiol 2022; 117:1405-1418. [PMID: 35510701 PMCID: PMC9794411 DOI: 10.1111/mmi.14916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 05/01/2022] [Accepted: 05/02/2022] [Indexed: 12/30/2022]
Abstract
M23 family endopeptidases play important roles in cell division and separation in a wide variety of bacteria. Recent studies have suggested that these proteins also contribute to bacterial virulence. However, the biological function of M23 peptidases in pathogenic spirochetes remains unexplored. Here, we describe Borrelia burgdorferi, the bacterial pathogen causing Lyme disease, requires a putative M23 family homolog, BB0761, for spirochete morphology and cell division. Indeed, the inactivation of bb0761 led to an aberrant filamentous phenotype as well as the impairment of B. burgdorferi growth in vitro. These phenotypes were complemented not only with B. burgdorferi bb0761, but also with the mepM gene from E. coli. Moreover, the bb0761 mutant showed a complete loss of infectivity in a murine model of Lyme borreliosis. Resistance of the mutant to osmotic and oxidative stresses was markedly reduced. Our combined results indicate that BB0761 contributes to B. burgdorferi cell division and virulence.
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Affiliation(s)
- Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Sierra George
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Maria L. White
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA
| | - Prahathees J. Eswara
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
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12
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Stevenson B, Krusenstjerna AC, Castro-Padovani TN, Savage CR, Jutras BL, Saylor TC. The Consistent Tick-Vertebrate Infectious Cycle of the Lyme Disease Spirochete Enables Borrelia burgdorferi To Control Protein Expression by Monitoring Its Physiological Status. J Bacteriol 2022; 204:e0060621. [PMID: 35380872 PMCID: PMC9112904 DOI: 10.1128/jb.00606-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The Lyme disease spirochete, Borrelia burgdorferi, persists in nature by alternatingly cycling between ticks and vertebrates. During each stage of the infectious cycle, B. burgdorferi produces surface proteins that are necessary for interactions with the tick or vertebrate tissues it encounters while also repressing the synthesis of unnecessary proteins. Among these are the Erp surface proteins, which are produced during vertebrate infection for interactions with host plasmin, laminin, glycosaminoglycans, and components of the complement system. Erp proteins are not expressed during tick colonization but are induced when the tick begins to ingest blood from a vertebrate host, a time when the bacteria undergo rapid growth and division. Using the erp genes as a model of borrelial gene regulation, our research group has identified three novel DNA-binding proteins that interact with DNA to control erp transcription. At least two of those regulators are, in turn, affected by DnaA, the master regulator of chromosome replication. Our data indicate that B. burgdorferi has evolved to detect the change from slow to rapid replication during tick feeding as a signal to begin expression of Erp and other vertebrate-specific proteins. The majority of other known regulatory factors of B. burgdorferi also respond to metabolic cues. These observations lead to a model in which the Lyme spirochete recognizes unique environmental conditions encountered during the infectious cycle to "know" where they are and adapt accordingly.
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Affiliation(s)
- Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky, USA
- Department of Entomology, University of Kentucky, Lexington, Kentucky, USA
| | - Andrew C. Krusenstjerna
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky, USA
| | - Tatiana N. Castro-Padovani
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky, USA
| | - Christina R. Savage
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky, USA
| | - Brandon L. Jutras
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Timothy C. Saylor
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky, USA
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13
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Groshong AM, Grassmann AA, Luthra A, McLain MA, Provatas AA, Radolf JD, Caimano MJ. PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi. PLoS Pathog 2021; 17:e1009725. [PMID: 34265024 PMCID: PMC8323883 DOI: 10.1371/journal.ppat.1009725] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 07/30/2021] [Accepted: 06/18/2021] [Indexed: 02/05/2023] Open
Abstract
In this study, we examined the relationship between c-di-GMP and its only known effector protein, PlzA, in Borrelia burgdorferi during the arthropod and mammalian phases of the enzootic cycle. Using a B. burgdorferi strain expressing a plzA point mutant (plzA-R145D) unable to bind c-di-GMP, we confirmed that the protective function of PlzA in ticks is c-di-GMP-dependent. Unlike ΔplzA spirochetes, which are severely attenuated in mice, the plzA-R145D strain was fully infectious, firmly establishing that PlzA serves a c-di-GMP-independent function in mammals. Contrary to prior reports, loss of PlzA did not affect expression of RpoS or RpoS-dependent genes, which are essential for transmission, mammalian host-adaptation and murine infection. To ascertain the nature of PlzA's c-di-GMP-independent function(s), we employed infection models using (i) host-adapted mutant spirochetes for needle inoculation of immunocompetent mice and (ii) infection of scid mice with in vitro-grown organisms. Both approaches substantially restored ΔplzA infectivity, suggesting that PlzA enables B. burgdorferi to overcome an early bottleneck to infection. Furthermore, using a Borrelia strain expressing a heterologous, constitutively active diguanylate cyclase, we demonstrate that 'ectopic' production of c-di-GMP in mammals abrogates spirochete virulence and interferes with RpoS function at the post-translational level in a PlzA-dependent manner. Structural modeling and SAXS analysis of liganded- and unliganded-PlzA revealed marked conformational changes that underlie its biphasic functionality. This structural plasticity likely enables PlzA to serve as a c-di-GMP biosensor that in its respective liganded and unliganded states promote vector- and host-adaptation by the Lyme disease spirochete.
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Affiliation(s)
- Ashley M. Groshong
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
| | - André A. Grassmann
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Melissa A. McLain
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Anthony A. Provatas
- Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, Connecticut, United States of America
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, United States of America
- Department of Genetics and Genome Science, UConn Health, Farmington, Connecticut, United States of America
- Department of Immunology, UConn Health, Farmington, Connecticut, United States of America
| | - Melissa J. Caimano
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, United States of America
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14
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Seshu J, Moy BE, Ingle TM. Transformation of Borrelia burgdorferi. Curr Protoc 2021; 1:e61. [PMID: 33661557 DOI: 10.1002/cpz1.61] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transformation techniques used to genetically manipulate Borrelia burgdorferi, the agent of Lyme disease, play a critical role in generating mutants that facilitate analyses of the role of genes in the pathophysiology of this bacterium. A number of borrelial mutants have been successfully isolated and characterized since the first electrotransformation procedure was established 25 years ago (Samuels, 1995). This article is directed at additional considerations for transforming infectious B. burgdorferi to generate strains retaining the plasmid profile of the parental strain, enabling analysis of transformants for in vitro and in vivo phenotypes. These methods are built on previously published protocols and are intended to add steps and tips to enhance transformation efficiency and recovery of strains amenable for studies involving colonization, survival, and transmission of B. burgdorferi during the vector and vertebrate phases of infection. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparation of stock cultures, propagation of spirochetes, and analysis of plasmid profiles Basic Protocol 2: Preparation of plasmid and linear DNA templates for transformation Basic Protocol 3: Transformation of B. burgdorferi Basic Protocol 4: Antibiotic selection of borrelial transformants Basic Protocol 5: Isolation of borrelial transformants in agar overlays Basic Protocol 6: Complementation of mutant borrelial strains in cis or in trans.
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Affiliation(s)
- J Seshu
- Department of Biology, South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, San Antonio, Texas
| | - Brian E Moy
- Department of Biology, South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, San Antonio, Texas
| | - Taylor MacMackin Ingle
- Department of Biology, South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, San Antonio, Texas
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15
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Davis MM, Brock AM, DeHart TG, Boribong BP, Lee K, McClune ME, Chang Y, Cramer N, Liu J, Jones CN, Jutras BL. The peptidoglycan-associated protein NapA plays an important role in the envelope integrity and in the pathogenesis of the lyme disease spirochete. PLoS Pathog 2021; 17:e1009546. [PMID: 33984073 PMCID: PMC8118282 DOI: 10.1371/journal.ppat.1009546] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/08/2021] [Indexed: 12/11/2022] Open
Abstract
The bacterial pathogen responsible for causing Lyme disease, Borrelia burgdorferi, is an atypical Gram-negative spirochete that is transmitted to humans via the bite of an infected Ixodes tick. In diderms, peptidoglycan (PG) is sandwiched between the inner and outer membrane of the cell envelope. In many other Gram-negative bacteria, PG is bound by protein(s), which provide both structural integrity and continuity between envelope layers. Here, we present evidence of a peptidoglycan-associated protein (PAP) in B. burgdorferi. Using an unbiased proteomics approach, we identified Neutrophil Attracting Protein A (NapA) as a PAP. Interestingly, NapA is a Dps homologue, which typically functions to bind and protect cellular DNA from damage during times of stress. While B. burgdorferi NapA is known to be involved in the oxidative stress response, it lacks the critical residues necessary for DNA binding. Biochemical and cellular studies demonstrate that NapA is localized to the B. burgdorferi periplasm and is indeed a PAP. Cryo-electron microscopy indicates that mutant bacteria, unable to produce NapA, have structural abnormalities. Defects in cell-wall integrity impact growth rate and cause the napA mutant to be more susceptible to osmotic and PG-specific stresses. NapA-linked PG is secreted in outer membrane vesicles and augments IL-17 production, relative to PG alone. Using microfluidics, we demonstrate that NapA acts as a molecular beacon-exacerbating the pathogenic properties of B. burgdorferi PG. These studies further our understanding of the B. burgdorferi cell envelope, provide critical information that underlies its pathogenesis, and highlight how a highly conserved bacterial protein can evolve mechanistically, while maintaining biological function.
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Affiliation(s)
- Marisela M. Davis
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Aaron M. Brock
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
- Molecular and Cellular Biology, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Tanner G. DeHart
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Brittany P. Boribong
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Katherine Lee
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Mecaila E. McClune
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Yunjie Chang
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, United States of America
| | - Nicholas Cramer
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, United States of America
| | - Caroline N. Jones
- Molecular and Cellular Biology, Virginia Tech, Blacksburg, Virginia, United States of America
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Brandon L. Jutras
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
- Molecular and Cellular Biology, Virginia Tech, Blacksburg, Virginia, United States of America
- Center for Emerging, Zoonotic and Arthropod-borne Pathogens, Virginia Tech, Blacksburg, Virginia, United States of America
- Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States of America
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16
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Tan X, Petri B, DeVinney R, Jenne CN, Chaconas G. The Lyme disease spirochete can hijack the host immune system for extravasation from the microvasculature. Mol Microbiol 2021; 116:498-515. [PMID: 33891779 DOI: 10.1111/mmi.14728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/30/2022]
Abstract
Lyme disease is the most common tick-transmitted disease in the northern hemisphere and is caused by the spirochete Borrelia burgdorferi and related Borrelia species. The constellation of symptoms attributable to this malady results from vascular dissemination of B. burgdorferi throughout the body to invade various tissue types. However, little is known about the mechanism by which the spirochetes can breach the blood vessel wall to reach distant tissues. We have studied this process by direct observation of spirochetes in the microvasculature of living mice using multi-laser spinning-disk intravital microscopy. Our results show that in our experimental system, instead of phagocytizing B. burgdorferi, host neutrophils are involved in the production of specific cytokines that activate the endothelium and potentiate B. burgdorferi escape into the surrounding tissue. Spirochete escape is not induced by paracellular permeability and appears to occur via a transcellular pathway. Neutrophil repurposing to promote bacterial extravasation represents a new and innovative pathogenic strategy.
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Affiliation(s)
- Xi Tan
- Department of Biochemistry & Molecular Biology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Björn Petri
- Department of Microbiology, Immunology & Infectious Diseases, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Rebekah DeVinney
- Department of Microbiology, Immunology & Infectious Diseases, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Craig N Jenne
- Department of Microbiology, Immunology & Infectious Diseases, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - George Chaconas
- Department of Biochemistry & Molecular Biology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.,Department of Microbiology, Immunology & Infectious Diseases, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
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17
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Chen Y, Vargas SM, Smith TC, Karna SLR, MacMackin Ingle T, Wozniak KL, Wormley FL, Seshu J. Borrelia peptidoglycan interacting Protein (BpiP) contributes to the fitness of Borrelia burgdorferi against host-derived factors and influences virulence in mouse models of Lyme disease. PLoS Pathog 2021; 17:e1009535. [PMID: 33882111 PMCID: PMC8092773 DOI: 10.1371/journal.ppat.1009535] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 05/03/2021] [Accepted: 04/07/2021] [Indexed: 12/17/2022] Open
Abstract
The Peptidoglycan (PG) cell wall of the Lyme disease (LD) spirochete, Borrelia burgdorferi (Bb), contributes to structural and morphological integrity of Bb; is a persistent antigen in LD patients; and has a unique pentapeptide with L-Ornithine as the third amino acid that cross-links its glycan polymers. A borrelial homolog (BB_0167) interacted specifically with borrelilal PG via its peptidoglycan interacting motif (MHELSEKRARAIGNYL); was localized to the protoplasmic cylinder of Bb; and was designated as Borrelia peptidoglycan interacting Protein (BpiP). A bpiP mutant displayed no defect under in vitro growth conditions with similar levels of several virulence-related proteins. However, the burden of bpiP mutant in C3H/HeN mice at day 14, 28 and 62 post-infection was significantly lower compared to control strains. No viable bpiP mutant was re-isolated from any tissues at day 62 post-infection although bpiP mutant was able to colonize immunodeficient SCID at day 28 post-infection. Acquisition or transmission of bpiP mutant by Ixodes scapularis larvae or nymphs respectively, from and to mice, was significantly lower compared to control strains. Further analysis of bpiP mutant revealed increased sensitivity to vancomycin, osmotic stress, lysosomal extracts, human antimicrobial peptide cathelicidin-LL37, complement-dependent killing in the presence of day 14 post-infection mouse serum and increased internalization of CFSC-labeled bpiP mutant by macrophages and dendritic cells compared to control strains. These studies demonstrate the importance of accessory protein/s involved in sustaining integrity of PG and cell envelope during different phases of Bb infection.
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Affiliation(s)
- Yue Chen
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Sean M. Vargas
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Trever C. Smith
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Sai Lakshmi Rajasekhar Karna
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Taylor MacMackin Ingle
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Karen L. Wozniak
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Floyd L. Wormley
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Janakiram Seshu
- South Texas Center for Emerging Infectious Diseases (STCEID) and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
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18
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Boyle WK, Richards CL, Dulebohn DP, Zalud AK, Shaw JA, Lovas S, Gherardini FC, Bourret TJ. DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity. PLoS Pathog 2021; 17:e1009072. [PMID: 33600418 PMCID: PMC7924775 DOI: 10.1371/journal.ppat.1009072] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/02/2021] [Accepted: 02/03/2021] [Indexed: 12/14/2022] Open
Abstract
Throughout its enzootic cycle, the Lyme disease spirochete Borreliella (Borrelia) burgdorferi, senses and responds to changes in its environment using a small repertoire of transcription factors that coordinate the expression of genes required for infection of Ixodes ticks and various mammalian hosts. Among these transcription factors, the DnaK suppressor protein (DksA) plays a pivotal role in regulating gene expression in B. burgdorferi during periods of nutrient limitation and is required for mammalian infectivity. In many pathogenic bacteria, the gene regulatory activity of DksA, along with the alarmone guanosine penta- and tetra-phosphate ((p)ppGpp), coordinate the stringent response to various environmental stresses, including nutrient limitation. In this study, we sought to characterize the role of DksA in regulating the transcriptional activity of RNA polymerase and its role in the regulation of RpoS-dependent gene expression required for B. burgdorferi infectivity. Using in vitro transcription assays, we observed recombinant DksA inhibits RpoD-dependent transcription by B. burgdorferi RNA polymerase independent of ppGpp. Additionally, we determined the pH-inducible expression of RpoS-dependent genes relies on DksA, but this relationship is independent of (p)ppGpp produced by Relbbu. Subsequent transcriptomic and western blot assays indicate DksA regulates the expression of BBD18, a protein previously implicated in the post-transcriptional regulation of RpoS. Moreover, we observed DksA was required for infection of mice following intraperitoneal inoculation or for transmission of B. burgdorferi by Ixodes scapularis nymphs. Together, these data suggest DksA plays a central role in coordinating transcriptional responses in B. burgdorferi required for infectivity through DksA’s interactions with RNA polymerase and post-transcriptional control of RpoS. Lyme disease, caused by the spirochete bacteria Borreliella (Borrelia) burgdorferi, is the most common vector-borne illness in North America. The ability of B. burgdorferi to establish infection is predicated by its ability to coordinate the expression of virulence factors in response to diverse environmental stimuli encountered within Ixodes ticks and mammalian hosts. Previous studies have shown an essential role for the alternative sigma factor RpoS in regulating the expression of genes required for the successful transmission of B. burgdorferi by Ixodes ticks and infection of mammalian hosts. The DnaK suppressor protein (DksA) is a global gene regulator in B. burgdorferi that contributes to the expression of RpoS-dependent genes. In this study, using in vitro transcription assays, we determined DksA exerts its gene regulatory function through direct interactions with the B. burgdorferi RNA polymerase and controls the expression of RpoS-dependent genes required for mammalian infection by post-transcriptionally regulating cellular levels of RpoS. Our results demonstrate the utility of in vitro transcription assays to determine how gene regulatory proteins like DksA control gene expression in B. burgdorferi and reveal a novel role for DksA in the infectious cycle of B. burgdorferi.
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Affiliation(s)
- William K. Boyle
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Crystal L. Richards
- Laboratory of Bacteriology, Gene Regulation Section, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Daniel P. Dulebohn
- Laboratory of Bacteriology, Gene Regulation Section, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Amanda K. Zalud
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Jeff A. Shaw
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Sándor Lovas
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska, United States of America
| | - Frank C. Gherardini
- Laboratory of Bacteriology, Gene Regulation Section, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Travis J. Bourret
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
- * E-mail:
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19
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Groshong AM, McLain MA, Radolf JD. Host-specific functional compartmentalization within the oligopeptide transporter during the Borrelia burgdorferi enzootic cycle. PLoS Pathog 2021; 17:e1009180. [PMID: 33428666 PMCID: PMC7822543 DOI: 10.1371/journal.ppat.1009180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/22/2021] [Accepted: 11/23/2020] [Indexed: 12/27/2022] Open
Abstract
Borrelia burgdorferi must acquire all of its amino acids (AAs) from its arthropod vector and vertebrate host. Previously, we determined that peptide uptake via the oligopeptide (Opp) ABC transporter is essential for spirochete viability in vitro and during infection. Our prior study also suggested that B. burgdorferi employs temporal regulation in concert with structural variation of oligopeptide-binding proteins (OppAs) to meet its AA requirements in each biological niche. Herein, we evaluated the contributions to the B. burgdorferi enzootic cycle of three of the spirochete's five OppAs (OppA1, OppA2, and OppA5). An oppA1 transposon (tn) mutant lysed in the hyperosmolar environment of the feeding tick, suggesting that OppA1 imports amino acids required for osmoprotection. The oppA2tn mutant displayed a profound defect in hematogenous dissemination in mice, yet persisted within skin while inducing only a minimal antibody response. These results, along with slightly decreased growth of the oppA2tn mutant within DMCs, suggest that OppA2 serves a minor nutritive role, while its dissemination defect points to an as yet uncharacterized signaling function. Previously, we identified a role for OppA5 in spirochete persistence within the mammalian host. We now show that the oppA5tn mutant displayed no defect during the tick phase of the cycle and could be tick-transmitted to naïve mice. Instead of working in tandem, however, OppA2 and OppA5 appear to function in a hierarchical manner; the ability of OppA5 to promote persistence relies upon the ability of OppA2 to facilitate dissemination. Structural homology models demonstrated variations within the binding pockets of OppA1, 2, and 5 indicative of different peptide repertoires. Rather than being redundant, B. burgdorferi's multiplicity of Opp binding proteins enables host-specific functional compartmentalization during the spirochete lifecycle.
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Affiliation(s)
- Ashley M. Groshong
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
- * E-mail:
| | - Melissa A. McLain
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, United States of America
- Department of Genetics and Genome Science, UConn Health, Farmington, Connecticut, United States of America
- Department of Immunology, UConn Health, Farmington, Connecticut, United States of America
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20
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Coburn J, Garcia B, Hu LT, Jewett MW, Kraiczy P, Norris SJ, Skare J. Lyme Disease Pathogenesis. Curr Issues Mol Biol 2020; 42:473-518. [PMID: 33353871 DOI: 10.21775/cimb.042.473] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Lyme disease Borrelia are obligately parasitic, tick- transmitted, invasive, persistent bacterial pathogens that cause disease in humans and non-reservoir vertebrates primarily through the induction of inflammation. During transmission from the infected tick, the bacteria undergo significant changes in gene expression, resulting in adaptation to the mammalian environment. The organisms multiply and spread locally and induce inflammatory responses that, in humans, result in clinical signs and symptoms. Borrelia virulence involves a multiplicity of mechanisms for dissemination and colonization of multiple tissues and evasion of host immune responses. Most of the tissue damage, which is seen in non-reservoir hosts, appears to result from host inflammatory reactions, despite the low numbers of bacteria in affected sites. This host response to the Lyme disease Borrelia can cause neurologic, cardiovascular, arthritic, and dermatologic manifestations during the disseminated and persistent stages of infection. The mechanisms by which a paucity of organisms (in comparison to many other infectious diseases) can cause varied and in some cases profound inflammation and symptoms remains mysterious but are the subjects of diverse ongoing investigations. In this review, we provide an overview of virulence mechanisms and determinants for which roles have been demonstrated in vivo, primarily in mouse models of infection.
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Affiliation(s)
- Jenifer Coburn
- Center For Infectious Disease Research, Medical College of Wisconsin, 8701 Watertown Plank Rd., TBRC C3980, Milwaukee, WI 53226, USA
| | - Brandon Garcia
- Department of Microbiology and Immunology, East Carolina University, Brody School of Medicine, Greenville, NC 27858, USA
| | - Linden T Hu
- Department of Molecular Biology and Microbiology, Vice Dean of Research, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA
| | - Mollie W Jewett
- Immunity and Pathogenesis Division Head, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, 6900 Lake Nona Blvd. Orlando, FL 32827, USA
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, University Hospital Frankfurt, Goethe University Frankfurt, Paul-Ehrlich-Str. 40, 60596 Frankfurt, Germany
| | - Steven J Norris
- Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, P.O. Box 20708, Houston, TX 77225, USA
| | - Jon Skare
- Professor and Associate Head, Texas A and M University, 8447 Riverside Pkwy, Bryan, TX 77807, USA
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Samuels DS, Lybecker MC, Yang XF, Ouyang Z, Bourret TJ, Boyle WK, Stevenson B, Drecktrah D, Caimano MJ. Gene Regulation and Transcriptomics. Curr Issues Mol Biol 2020; 42:223-266. [PMID: 33300497 DOI: 10.21775/cimb.042.223] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Borrelia (Borreliella) burgdorferi, along with closely related species, is the etiologic agent of Lyme disease. The spirochete subsists in an enzootic cycle that encompasses acquisition from a vertebrate host to a tick vector and transmission from a tick vector to a vertebrate host. To adapt to its environment and persist in each phase of its enzootic cycle, B. burgdorferi wields three systems to regulate the expression of genes: the RpoN-RpoS alternative sigma factor cascade, the Hk1/Rrp1 two-component system and its product c-di-GMP, and the stringent response mediated by RelBbu and DksA. These regulatory systems respond to enzootic phase-specific signals and are controlled or fine- tuned by transcription factors, including BosR and BadR, as well as small RNAs, including DsrABb and Bb6S RNA. In addition, several other DNA-binding and RNA-binding proteins have been identified, although their functions have not all been defined. Global changes in gene expression revealed by high-throughput transcriptomic studies have elucidated various regulons, albeit technical obstacles have mostly limited this experimental approach to cultivated spirochetes. Regardless, we know that the spirochete, which carries a relatively small genome, regulates the expression of a considerable number of genes required for the transitions between the tick vector and the vertebrate host as well as the adaptation to each.
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Affiliation(s)
- D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Meghan C Lybecker
- Department of Biology, University of Colorado, Colorado Springs, CO 80918, USA
| | - X Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Travis J Bourret
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE, 68105 USA
| | - William K Boyle
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE, 68105 USA
| | - Brian Stevenson
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky School of Medicine, Lexington, KY 40536, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Melissa J Caimano
- Departments of Medicine, Pediatrics, and Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
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Pal U, Kitsou C, Drecktrah D, Yaş ÖB, Fikrig E. Interactions Between Ticks and Lyme Disease Spirochetes. Curr Issues Mol Biol 2020; 42:113-144. [PMID: 33289683 DOI: 10.21775/cimb.042.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Borrelia burgdorferi sensu lato causes Lyme borreliosis in a variety of animals and humans. These atypical bacterial pathogens are maintained in a complex enzootic life cycle that primarily involves a vertebrate host and Ixodes spp. ticks. In the Northeastern United States, I. scapularis is the main vector, while wild rodents serve as the mammalian reservoir host. As B. burgdorferi is transmitted only by I. scapularis and closely related ticks, the spirochete-tick interactions are thought to be highly specific. Various borrelial and arthropod proteins that directly or indirectly contribute to the natural cycle of B. burgdorferi infection have been identified. Discrete molecular interactions between spirochetes and tick components also have been discovered, which often play critical roles in pathogen persistence and transmission by the arthropod vector. This review will focus on the past discoveries and future challenges that are relevant to our understanding of the molecular interactions between B. burgdorferi and Ixodes ticks. This information will not only impact scientific advancements in the research of tick- transmitted infections but will also contribute to the development of novel preventive measures that interfere with the B. burgdorferi life cycle.
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Affiliation(s)
- Utpal Pal
- Department of Veterinary Medicine, University of Maryland, 8075 Greenmead Drive, College Park, MD 20742, USA
| | - Chrysoula Kitsou
- Department of Veterinary Medicine, University of Maryland, 8075 Greenmead Drive, College Park, MD 20742, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Özlem Büyüktanir Yaş
- Department of Microbiology and Clinical Microbiology, Faculty of Medicine, Istinye University, Zeytinburnu, İstanbul, 34010, Turkey
| | - Erol Fikrig
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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23
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The BB0345 Hypothetical Protein of Borrelia burgdorferi Is Essential for Mammalian Infection. Infect Immun 2020; 88:IAI.00472-20. [PMID: 32928963 DOI: 10.1128/iai.00472-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/04/2020] [Indexed: 12/18/2022] Open
Abstract
During the natural enzootic life cycle of Borrelia burgdorferi (also known as Borreliella burgdorferi), the bacteria must sense conditions within the vertebrate and arthropod and appropriately regulate expression of genes necessary to persist within these distinct environments. bb0345 of B. burgdorferi encodes a hypothetical protein of unknown function that is predicted to contain an N-terminal helix-turn-helix (HTH) domain. Because HTH domains can mediate protein-DNA interactions, we hypothesized that BB0345 might represent a previously unidentified borrelial transcriptional regulator with the ability to regulate events critical for the B. burgdorferi enzootic cycle. To study the role of BB0345 within mammals, we generated a bb0345 mutant and assessed its virulence potential in immunocompetent mice. The bb0345 mutant was able to initiate localized infection and disseminate to distal tissues but was cleared from all sites by 14 days postinfection. In vitro growth curve analyses revealed that the bb0345 mutant grew similar to wild-type bacteria in standard Barbour-Stoenner-Kelley II (BSK-II) medium; however, the mutant was not able to grow in dilute BSK-II medium or dialysis membrane chambers (DMCs) implanted in rats. Proteinase K accessibility assays and whole-cell partitioning indicated that BB0345 was intracellular and partially membrane associated. Comparison of protein production profiles between the wild-type parent and the bb0345 mutant revealed no major differences, suggesting BB0345 may not be a global transcriptional regulator. Taken together, these data show that BB0345 is essential for B. burgdorferi survival in the mammalian host, potentially by aiding the spirochete with a physiological function that is required by the bacterium during infection.
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Bensaoud C, Martins LA, Aounallah H, Hackenberg M, Kotsyfakis M. Emerging roles of non-coding RNAs in vector-borne infections. J Cell Sci 2020; 134:134/5/jcs246744. [PMID: 33154170 DOI: 10.1242/jcs.246744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Non-coding RNAs (ncRNAs) are nucleotide sequences that are known to assume regulatory roles previously thought to be reserved for proteins. Their functions include the regulation of protein activity and localization and the organization of subcellular structures. Sequencing studies have now identified thousands of ncRNAs encoded within the prokaryotic and eukaryotic genomes, leading to advances in several fields including parasitology. ncRNAs play major roles in several aspects of vector-host-pathogen interactions. Arthropod vector ncRNAs are secreted through extracellular vesicles into vertebrate hosts to counteract host defense systems and ensure arthropod survival. Conversely, hosts can use specific ncRNAs as one of several strategies to overcome arthropod vector invasion. In addition, pathogens transmitted through vector saliva into vertebrate hosts also possess ncRNAs thought to contribute to their pathogenicity. Recent studies have addressed ncRNAs in vectors or vertebrate hosts, with relatively few studies investigating the role of ncRNAs derived from pathogens and their involvement in establishing infections, especially in the context of vector-borne diseases. This Review summarizes recent data focusing on pathogen-derived ncRNAs and their role in modulating the cellular responses that favor pathogen survival in the vertebrate host and the arthropod vector, as well as host ncRNAs that interact with vector-borne pathogens.
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Affiliation(s)
- Chaima Bensaoud
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005, Ceske Budejovice (Budweis), Czechia
| | - Larissa Almeida Martins
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005, Ceske Budejovice (Budweis), Czechia
| | - Hajer Aounallah
- Université de Tunis El Manar, Institut Pasteur de Tunis, LR11IPT03, Service d'entomologie médicale, 1002, Tunis, Tunisie.,Innovation and Development Laboratory, Innovation and Development Center, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Michael Hackenberg
- Dpto. de Genética, Facultad de Ciencias, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain.,Lab. de Bioinformática, Centro de Investigación Biomédica, PTS, Instituto de Biotecnología, Avda. del Conocimiento s/n, Granada 18100, Spain
| | - Michail Kotsyfakis
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005, Ceske Budejovice (Budweis), Czechia
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25
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Liu Q, Xu H, Zhang Y, Yang J, Du J, Zhou Y, Yang XF, Lou Y. Role of HK2 in the Enzootic Cycle of Borrelia burgdorferi. Front Med (Lausanne) 2020; 7:573648. [PMID: 33195322 PMCID: PMC7649798 DOI: 10.3389/fmed.2020.573648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/07/2020] [Indexed: 12/19/2022] Open
Abstract
The two-component response regulator Rrp2 is a key activator controlling the production of numerous virulence factors of Borrelia burgdorferi, the Lyme disease pathogen. Previously it was shown that the cognate histidine kinase HK2 is not required for Rrp2 activation in vitro, nor for mammalian infection upon needle inoculation, raising the question whether HK2 has any role in the enzootic cycle of B. burgdorferi. In this study, we demonstrated that HK2 is not required for spirochetal survival in the tick vector. When fed on naive mice, the hk2 mutant had reduced infectivity through the route of tick bite, suggesting that the spirochetes lacking HK2 had a disadvantage in the enzootic cycle. Furthermore, overexpression of hk2 reduced the level of Rrp2 phosphorylation, suggesting that HK2 can function as a phosphatase to dephosphorylate Rrp2. Strains overexpressing hk2 impaired the expression of RpoN regulon whose activation is dependent on Rrp2 phosphorylation and activation, and had reduced infectivity in mice. Taken together, these results demonstrate that although HK2 does not play an essential role in Rrp2 activation, it is important for the optimal fitness of B. burgdorferi in the enzootic cycle.
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Affiliation(s)
- Qiang Liu
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Haijun Xu
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Yan Zhang
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, United States
- Optometry and Eye Hospital and School of Ophthalmology, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, China
| | - Jing Yang
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Jimei Du
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Yan Zhou
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Yongliang Lou
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
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Zhang Y, Chen T, Raghunandanan S, Xiang X, Yang J, Liu Q, Edmondson DG, Norris SJ, Yang XF, Lou Y. YebC regulates variable surface antigen VlsE expression and is required for host immune evasion in Borrelia burgdorferi. PLoS Pathog 2020; 16:e1008953. [PMID: 33048986 PMCID: PMC7584230 DOI: 10.1371/journal.ppat.1008953] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/23/2020] [Accepted: 09/02/2020] [Indexed: 02/08/2023] Open
Abstract
Borrelia burgdorferi, the Lyme disease pathogen causes persistent infection by evading the host immune response. Differential expression of the surface-exposed lipoprotein VlsE that undergoes antigenic variation is a key immune evasion strategy employed by B. burgdorferi. Most studies focused on the mechanism of VlsE antigen variation, but little is known about VlsE regulation and factor(s) that regulates differential vlsE expression. In this study, we investigated BB0025, a putative YebC family transcriptional regulator (and hence designated BB0025 as YebC of B. burgdorferi herein). We constructed yebC mutant and complemented strain in an infectious strain of B. burgdorferi. The yebC mutant could infect immunocompromised SCID mice but not immunocompetent mice, suggesting that YebC plays an important role in evading host adaptive immunity. RNA-seq analyses identified vlsE as one of the genes whose expression was most affected by YebC. Quantitative RT-PCR and Western blot analyses confirmed that vlsE expression was dependent on YebC. In vitro, YebC and VlsE were co-regulated in response to growth temperature. In mice, both yebC and vlsE were inversely expressed with ospC in response to the host adaptive immune response. Furthermore, EMSA proved that YebC directly binds to the vlsE promoter, suggesting a direct transcriptional control. These data demonstrate that YebC is a new regulator that modulates expression of vlsE and other genes important for spirochetal infection and immune evasion in the mammalian host.
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Affiliation(s)
- Yan Zhang
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
- Optometry and Eye Hospital and School of Ophthalmology, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, China
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Tong Chen
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Pediatrics, Division of Medical Genetics, Duke University, Durham, North Carolina, United States of America
| | - Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Xuwu Xiang
- Department of Anesthesiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Jing Yang
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Qiang Liu
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Diane G. Edmondson
- Department of Pathology and Laboratory Medicine, UTHealth Medical School, Houston, Texas, United States of America
| | - Steven J. Norris
- Department of Pathology and Laboratory Medicine, UTHealth Medical School, Houston, Texas, United States of America
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Yongliang Lou
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
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Serologic Evidence for the Exposure of Eastern Coyotes ( Canis latrans) in Pennsylvania to the Tick-Borne Pathogens Borreliella burgdorferi and Anaplasma phagocytophilum. mSphere 2020; 5:5/4/e00544-20. [PMID: 32817454 PMCID: PMC7426170 DOI: 10.1128/msphere.00544-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The incidence of Lyme disease (Borreliella burgdorferi) and anaplasmosis (Anaplasma phagocytophilum) are increasing in North America and Europe. The causative agents of these debilitating tick-transmitted infections are maintained in nature in an enzootic cycle involving Ixodes ticks and diverse mammals and birds. It has been postulated that predators directly or indirectly influence the dynamics of the enzootic cycle and disease incidence. Here, we demonstrate high seropositivity of eastern coyotes for B. burgdorferi and A. phagocytophilum. As coyotes become established in urban and suburban environments, interactions with humans, companion animals, and urban/suburban wildlife will increase. Knowledge of the pathogens that these highly adaptable predators are exposed to or carry, and their potential to influence or participate in enzootic cycles, is central to efforts to reduce the risk of tick-borne diseases in humans and companion animals. Lyme disease and anaplasmosis are tick-borne bacterial diseases caused by Borreliella and Anaplasma species, respectively. A comprehensive analysis of the exposure of eastern coyotes (Canis latrans) in the northeastern United States to tick-borne pathogens has not been conducted. In this report, we assess the serological status of 128 eastern coyotes harvested in Pennsylvania in 2015 and 2017 for antibodies to Borreliella burgdorferi and Anaplasma phagocytophilum. Immunoblot and dot blot approaches were employed to test each plasma sample by using cell lysates and recombinant proteins as detection antigens. The results demonstrate high seropositivity incidences of 64.8% and 72.7% for B. burgdorferi and A. phagocytophilum, respectively. Antibodies to both pathogens were detected in 51.5% of the plasma samples, indicating high potential for coinfection. Antibodies to the B. burgdorferi proteins DbpB, VlsE, DbpA, BBA36, and OspF (BBO39) were detected in 67.2, 63.3, 56.2, 51.6, and 48.4% of the plasma samples, respectively. Antibodies to the A. phagocytophilum P44 and P130 proteins were detected in 72.7 and 60.9% of the plasma samples, respectively. IMPORTANCE The incidence of Lyme disease (Borreliella burgdorferi) and anaplasmosis (Anaplasma phagocytophilum) are increasing in North America and Europe. The causative agents of these debilitating tick-transmitted infections are maintained in nature in an enzootic cycle involving Ixodes ticks and diverse mammals and birds. It has been postulated that predators directly or indirectly influence the dynamics of the enzootic cycle and disease incidence. Here, we demonstrate high seropositivity of eastern coyotes for B. burgdorferi and A. phagocytophilum. As coyotes become established in urban and suburban environments, interactions with humans, companion animals, and urban/suburban wildlife will increase. Knowledge of the pathogens that these highly adaptable predators are exposed to or carry, and their potential to influence or participate in enzootic cycles, is central to efforts to reduce the risk of tick-borne diseases in humans and companion animals.
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Saputra EP, Trzeciakowski JP, Hyde JA. Borrelia burgdorferi spatiotemporal regulation of transcriptional regulator bosR and decorin binding protein during murine infection. Sci Rep 2020; 10:12534. [PMID: 32719448 PMCID: PMC7385660 DOI: 10.1038/s41598-020-69212-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 07/07/2020] [Indexed: 12/18/2022] Open
Abstract
Lyme disease, caused by Borrelia burgdorferi, is an inflammatory multistage infection, consisting of localized, disseminated, and persistent disease stages, impacting several organ systems through poorly defined gene regulation mechanisms. The purpose of this study is to further characterize the spatiotemporal transcriptional regulation of B. burgdorferi during mammalian infection of borrelial oxidative stress regulator (bosR) and decorin binding protein (dbpBA) by utilizing bioluminescent B. burgdorferi reporter strains and in vivo imaging. Fluctuating borrelial load was also monitored and used for normalization to evaluate expression levels. bosR transcription is driven by two promoters, Pbb0648 and PbosR, and we focused on the native promoter. bosR expression is low relative to the robustly expressed dbpBA throughout infection. In distal tissues, bosR was the highest in the heart during in the first week whereas dbpBA was readily detectable at all time points with each tissue displaying a distinct expression pattern. This data suggests bosR may have a role in heart colonization and the induction of dbpBA indicates a RpoS independent transcriptional regulation occurring in the mammalian cycle of pathogenesis. These finding demonstrate that B. burgdorferi engages unknown genetic mechanisms to uniquely respond to mammalian tissue environments and/or changing host response over time.
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Affiliation(s)
- Elizabeth P Saputra
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Bryan, TX, USA
| | - Jerome P Trzeciakowski
- Department of Medical Physiology, College of Medicine, Texas A&M Health Science Center, Bryan, TX, USA
| | - Jenny A Hyde
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Bryan, TX, USA.
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29
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Abstract
Borrelia burgdorferi is the causative agent of Lyme disease and is transmitted to vertebrate hosts by Ixodes spp. ticks. The spirochaete relies heavily on its arthropod host for basic metabolic functions and has developed complex interactions with ticks to successfully colonize, persist and, at the optimal time, exit the tick. For example, proteins shield spirochaetes from immune factors in the bloodmeal and facilitate the transition between vertebrate and arthropod environments. On infection, B. burgdorferi induces selected tick proteins that modulate the vector gut microbiota towards an environment that favours colonization by the spirochaete. Additionally, the recent sequencing of the Ixodes scapularis genome and characterization of tick immune defence pathways, such as the JAK–STAT, immune deficiency and cross-species interferon-γ pathways, have advanced our understanding of factors that are important for B. burgdorferi persistence in the tick. In this Review, we summarize interactions between B. burgdorferi and I. scapularis during infection, as well as interactions with tick gut and salivary gland proteins important for establishing infection and transmission to the vertebrate host. Borrelia burgdorferi has a complex life cycle with several different hosts, causing Lyme disease when it infects humans. In this Review, Fikrig and colleagues discuss how B. burgdorferi infects and interacts with its tick vector to ensure onward transmission.
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30
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Snow S, Bacon E, Bergeron J, Katzman D, Wilhelm A, Lewis O, Syangtan D, Calkins A, Archambault L, Anacker ML, Schlax PJ. Transcript decay mediated by RNase III in Borrelia burgdorferi. Biochem Biophys Res Commun 2020; 529:386-391. [PMID: 32703440 DOI: 10.1016/j.bbrc.2020.05.201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 05/26/2020] [Indexed: 11/29/2022]
Abstract
The causative agent of Lyme disease, Borrelia burgdorferi, requires shifts in gene expression to undergo its natural enzootic cycle between tick and vertebrate hosts. mRNA decay mechanisms play significant roles in governing gene expression in other bacteria, but are not yet characterized in B. burgdorferi. RNase III is an important enzyme in processing ribosomal RNA, but it also plays a role in mRNA decay in many bacteria. We compared RNA decay profiles and steady-state abundances of transcripts in wild-type Borrelia burgdorferi strain B31 and in an RNase III null (rnc-) mutant. Transcripts encoding RNA polymerase subunits (rpoA and rpoS), ribosomal proteins (rpsD, rpsK, rpsM, rplQ, and rpsO), a nuclease (pnp), a flagellar protein (flaB), and a translational regulator (bpuR) decayed more rapidly in the wild-type strain than in the slow growing rnc- mutant indicating that RNA turnover is mediated by RNase III in the bacterium that causes Lyme disease. Additionally, in wild type bacteria, RNA decay rates of rpoS, rpoN, ospA, ospC, bpuR and dbpA transcripts are only modestly affected by changes in the osmolarity.
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Affiliation(s)
- Santina Snow
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Emily Bacon
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Jennifer Bergeron
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - David Katzman
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Amelia Wilhelm
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Owen Lewis
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Deepsing Syangtan
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Andrew Calkins
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Linda Archambault
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Melissa L Anacker
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Paula Jean Schlax
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA.
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The Lon-1 Protease Is Required by Borrelia burgdorferi To Infect the Mammalian Host. Infect Immun 2020; 88:IAI.00951-19. [PMID: 32205400 DOI: 10.1128/iai.00951-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/14/2020] [Indexed: 01/23/2023] Open
Abstract
Borrelia burgdorferi encodes a functional homolog of canonical Lon protease termed Lon-2. In addition, B. burgdorferi encodes a second Lon homolog called Lon-1. Recent studies suggest that Lon-1 may function differently from the prototypical Lon protease. However, the function of Lon-1 in B. burgdorferi biology remains virtually unknown. Particularly, the contribution of Lon-1 to B. burgdorferi fitness and infection remains hitherto unexplored. Herein, we show that Lon-1 plays a critical role for the infection of B. burgdorferi in a mammalian host. We found that lon-1 was highly expressed during animal infection, implying an important function of this protein in bacterial infection. We further generated a lon-1 deletion mutant and an isogenic complemented strain. Relative to that of the wild-type strain, the infectivity of the mutant was severely attenuated in a murine infection model. Our data also showed that the mutant displayed growth defects in regular BSK-II medium. Furthermore, bacterial resistance to osmotic stress was markedly reduced when lon-1 was inactivated. When exposed to tert-butyl hydroperoxide, survival of the lon-1 mutant was impaired. In addition, production of several virulence factors, such as BosR, RpoS, and OspC, was elevated in the mutant. These phenotypes were restored when the lon-1 mutation was complemented. Finally, we created a lon-1(S714A) mutant and found that this mutant failed to infect mice, suggesting that the proteolytic activity of Lon-1 is essential for bacterial infection. Taken together, these results demonstrate that Lon-1 is required by B. burgdorferi to infect animal hosts and to cope with environmental stresses.
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Establishment of an in vitro RNA polymerase transcription system: a new tool to study transcriptional activation in Borrelia burgdorferi. Sci Rep 2020; 10:8246. [PMID: 32427963 PMCID: PMC7237435 DOI: 10.1038/s41598-020-65104-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/27/2020] [Indexed: 12/04/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi exhibits dramatic changes in gene expression as it transits between its tick vector and vertebrate host. A major hurdle to understanding the mechanisms underlying gene regulation in B. burgdorferi has been the lack of a functional assay to test how gene regulatory proteins and sigma factors interact with RNA polymerase to direct transcription. To gain mechanistic insight into transcriptional control in B. burgdorferi, and address sigma factor function and specificity, we developed an in vitro transcription assay using the B. burgdorferi RNA polymerase holoenzyme. We established reaction conditions for maximal RNA polymerase activity by optimizing pH, temperature, and the requirement for divalent metals. Using this assay system, we analyzed the promoter specificity of the housekeeping sigma factor RpoD to promoters encoding previously identified RpoD consensus sequences in B. burgdorferi. Collectively, this study established an in vitro transcription assay that revealed RpoD-dependent promoter selectivity by RNA polymerase and the requirement of specific metal cofactors for maximal RNA polymerase activity. The establishment of this functional assay will facilitate molecular and biochemical studies on how gene regulatory proteins and sigma factors exert control of gene expression in B. burgdorferi required for the completion of its enzootic cycle.
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Medina-Pérez DN, Wager B, Troy E, Gao L, Norris SJ, Lin T, Hu L, Hyde JA, Lybecker M, Skare JT. The intergenic small non-coding RNA ittA is required for optimal infectivity and tissue tropism in Borrelia burgdorferi. PLoS Pathog 2020; 16:e1008423. [PMID: 32365143 PMCID: PMC7224557 DOI: 10.1371/journal.ppat.1008423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/14/2020] [Accepted: 04/01/2020] [Indexed: 12/15/2022] Open
Abstract
Post-transcriptional regulation via small regulatory RNAs (sRNAs) has been implicated in diverse regulatory processes in bacteria, including virulence. One class of sRNAs, termed trans-acting sRNAs, can affect the stability and/or the translational efficiency of regulated transcripts. In this study, we utilized a collaborative approach that employed data from infection with the Borrelia burgdorferi Tn library, coupled with Tn-seq, together with borrelial sRNA and total RNA transcriptomes, to identify an intergenic trans-acting sRNA, which we designate here as ittA for infectivity-associated and tissue-tropic sRNA locus A. The genetic inactivation of ittA resulted in a significant attenuation in infectivity, with decreased spirochetal load in ear, heart, skin and joint tissues. In addition, the ittA mutant did not disseminate to peripheral skin sites or heart tissue, suggesting a role for ittA in regulating a tissue-tropic response. RNA-Seq analysis determined that 19 transcripts were differentially expressed in the ittA mutant relative to its genetic parent, including vraA, bba66, ospD and oms28 (bba74). Subsequent proteomic analyses also showed a significant decrease of OspD and Oms28 (BBA74) proteins. To our knowledge this is the first documented intergenic sRNA that alters the infectivity potential of B. burgdorferi.
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Affiliation(s)
- Diana N. Medina-Pérez
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, United States of America
| | - Beau Wager
- Department of Molecular Biology and Microbiology, Tufts University, School of Medicine, Boston, Massachusetts, United States of America
| | - Erin Troy
- Department of Molecular Biology and Microbiology, Tufts University, School of Medicine, Boston, Massachusetts, United States of America
| | - Lihui Gao
- Department of Pathology and Laboratory Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Houston, Texas, United States of America
| | - Steven J. Norris
- Department of Pathology and Laboratory Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Houston, Texas, United States of America
| | - Tao Lin
- Department of Pathology and Laboratory Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Houston, Texas, United States of America
| | - Linden Hu
- Department of Molecular Biology and Microbiology, Tufts University, School of Medicine, Boston, Massachusetts, United States of America
| | - Jenny A. Hyde
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, United States of America
| | - Meghan Lybecker
- Department of Biology, University of Colorado at Colorado Springs, Colorado Springs, Colorado, United States of America
| | - Jon T. Skare
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, United States of America
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34
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Mason C, Thompson C, Ouyang Z. DksA plays an essential role in regulating the virulence of Borrelia burgdorferi. Mol Microbiol 2020; 114:172-183. [PMID: 32227372 DOI: 10.1111/mmi.14504] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/13/2020] [Accepted: 03/20/2020] [Indexed: 12/16/2022]
Abstract
The RNA polymerase-binding protein DksA, together with the alarmone nucleotides (p)ppGpp, mediates the stringent response to nutrient starvation in Borrelia burgdorferi. To date, the contribution of DksA to B. burgdorferi infection remains unknown. We report here that DksA is essential for B. burgdorferi to infect a mammalian host. dksA expression was highly induced during infection. Moreover, a dksA-deficient mutant was incapable of infecting mice. The mutant displayed growth defects when cultured in vitro and resistance to osmotic pressure was markedly reduced. These phenotypes were fully restored to those of the wild type when dksA mutation was complemented. We further showed that DksA controlled the expression of virulence-associated lipoprotein OspC, likely via the central alternative sigma factor RpoS. Synthesis of RpoS was abolished in the dksA mutant, but rpoS transcription remained unaffected. Additionally, we found that the expression of clpX, clpA, clpP, and clpP2 was significantly increased in the mutant, suggesting that DksA may post-transcriptionally regulate rpoS expression via its effect on ClpXP and/or ClpAP proteases. These combined data demonstrate that DksA regulates B. burgdorferi virulence at least partially through its influence on RpoS and OspC. This study thus elucidates that, in addition to function as a stringent response regulator, DksA promotes the transcription and/or translation of genes contributing to B. burgdorferi infectivity.
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Affiliation(s)
- Charlotte Mason
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
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35
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Drecktrah D, Hall LS, Brinkworth AJ, Comstock JR, Wassarman KM, Samuels DS. Characterization of 6S RNA in the Lyme disease spirochete. Mol Microbiol 2020; 113:399-417. [PMID: 31742773 PMCID: PMC7047579 DOI: 10.1111/mmi.14427] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 11/05/2019] [Accepted: 11/16/2019] [Indexed: 12/31/2022]
Abstract
6S RNA binds to RNA polymerase and regulates gene expression, contributing to bacterial adaptation to environmental stresses. In this study, we examined the role of 6S RNA in murine infectivity and tick persistence of the Lyme disease spirochete Borrelia (Borreliella) burgdorferi. B. burgdorferi 6S RNA (Bb6S RNA) binds to RNA polymerase, is expressed independent of growth phase or nutrient stress in culture, and is processed by RNase Y. We found that rny (bb0504), the gene encoding RNase Y, is essential for B. burgdorferi growth, while ssrS, the gene encoding 6S RNA, is not essential, indicating a broader role for RNase Y activity in the spirochete. Bb6S RNA regulates expression of the ospC and dbpA genes encoding outer surface protein C and decorin binding protein A, respectively, which are lipoproteins important for host infection. The highest levels of Bb6S RNA are found when the spirochete resides in unfed nymphs. ssrS mutants lacking Bb6S RNA were compromised for infectivity by needle inoculation, but injected mice seroconverted, indicating an ability to activate the adaptive immune response. ssrS mutants were successfully acquired by larval ticks and persisted through fed nymphs. Bb6S RNA is one of the first regulatory RNAs identified in B. burgdorferi that controls the expression of lipoproteins involved in host infectivity.
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Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | | | | | - Karen M. Wassarman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - D. Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA
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36
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Mason C, Thompson C, Ouyang Z. The Lon-2 protease of Borrelia burgdorferi is critical for infection in the mammalian host. Mol Microbiol 2020; 113:938-950. [PMID: 31955462 DOI: 10.1111/mmi.14460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/10/2020] [Accepted: 01/13/2020] [Indexed: 01/08/2023]
Abstract
Borrelia burgdorferi encodes a functional homolog of canonical Lon protease termed Lon-2. To date, the contribution of Lon-2 to B. burgdorferi fitness and infection remains unexplored. Herein, we showed that expression of lon-2 was highly induced during animal infection, suggesting that Lon-2 is important for B. burgdorferi infection. We further generated a lon-2 deletion mutant. Compared with that of wild-type (WT) strain, the infectivity of the mutant was severely attenuated in a murine infection model. Although no growth defect was observed for the mutant in normal BSK-II medium, resistance of the lon-2 mutant to osmotic stress was markedly reduced. In addition, when exposed to tert-Butyl hydroperoxide, survival of the lon-2 mutant was impaired. In addition, we found that the protein levels of RpoS and RpoS-dependent OspC were decreased in the mutant. All these phenotypes were restored to WT or near-WT levels when lon-2 mutation was complemented in cis. Taken together, these results demonstrate that Lon-2 is critical for B. burgdorferi to establish infection and to cope with environmental stresses. This study provides a foundation for further uncovering the direct link between the dual roles of Lon-2 in protein quality control and bacterial pathogenesis.
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Affiliation(s)
- Charlotte Mason
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
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37
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Hognon C, Garaude S, Timmins J, Chipot C, Dehez F, Monari A. Molecular Bases of DNA Packaging in Bacteria Revealed by All-Atom Molecular Dynamics Simulations: The Case of Histone-Like Proteins in Borrelia burgdorferi. J Phys Chem Lett 2019; 10:7200-7207. [PMID: 31693374 DOI: 10.1021/acs.jpclett.9b02978] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
DNA compaction is essential to ensure the packaging of the genetic material in living cells and also plays a key role in the epigenetic regulation of gene expression. In both humans and bacteria, DNA packaging is achieved by specific well-conserved proteins. Here, by means of all-atom molecular dynamics simulations, including the determination of relevant free-energy profiles, we rationalize the molecular bases for this remarkable process in bacteria, illustrating the crucial role played by positively charged amino acids of a small histone-like protein. We also present compelling evidence that this histone-like protein alone can induce strong bending of a DNA duplex around its core domain, a process that requires overcoming a major free-energy barrier.
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Affiliation(s)
- Cécilia Hognon
- Université de Lorraine and CNRS, LPCT UMR 7019 , F-54000 Nancy , France
| | - Simon Garaude
- Université de Lorraine and CNRS, LPCT UMR 7019 , F-54000 Nancy , France
| | - Joanna Timmins
- Université Grenoble Alpes , CNRS, CEA, IBS , F-38000 Grenoble , France
| | - Christophe Chipot
- Université de Lorraine and CNRS, LPCT UMR 7019 , F-54000 Nancy , France
- Department of Physics , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801 , United States
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign , 54506 Vandoeuvre-lès-Nancy Cedex, France
| | - François Dehez
- Université de Lorraine and CNRS, LPCT UMR 7019 , F-54000 Nancy , France
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign , 54506 Vandoeuvre-lès-Nancy Cedex, France
| | - Antonio Monari
- Université de Lorraine and CNRS, LPCT UMR 7019 , F-54000 Nancy , France
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38
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Caimano MJ, Groshong AM, Belperron A, Mao J, Hawley KL, Luthra A, Graham DE, Earnhart CG, Marconi RT, Bockenstedt LK, Blevins JS, Radolf JD. The RpoS Gatekeeper in Borrelia burgdorferi: An Invariant Regulatory Scheme That Promotes Spirochete Persistence in Reservoir Hosts and Niche Diversity. Front Microbiol 2019; 10:1923. [PMID: 31507550 PMCID: PMC6719511 DOI: 10.3389/fmicb.2019.01923] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/05/2019] [Indexed: 11/28/2022] Open
Abstract
Maintenance of Borrelia burgdorferi within its enzootic cycle requires a complex regulatory pathway involving the alternative σ factors RpoN and RpoS and two ancillary trans-acting factors, BosR and Rrp2. Activation of this pathway occurs within ticks during the nymphal blood meal when RpoS, the effector σ factor, transcribes genes required for tick transmission and mammalian infection. RpoS also exerts a 'gatekeeper' function by repressing σ70-dependent tick phase genes (e.g., ospA, lp6.6). Herein, we undertook a broad examination of RpoS functionality throughout the enzootic cycle, beginning with modeling to confirm that this alternative σ factor is a 'genuine' RpoS homolog. Using a novel dual color reporter system, we established at the single spirochete level that ospA is expressed in nymphal midguts throughout transmission and is not downregulated until spirochetes have been transmitted to a naïve host. Although it is well established that rpoS/RpoS is expressed throughout infection, its requirement for persistent infection has not been demonstrated. Plasmid retention studies using a trans-complemented ΔrpoS mutant demonstrated that (i) RpoS is required for maximal fitness throughout the mammalian phase and (ii) RpoS represses tick phase genes until spirochetes are acquired by a naïve vector. By transposon mutant screening, we established that bba34/oppA5, the only OppA oligopeptide-binding protein controlled by RpoS, is a bona fide persistence gene. Lastly, comparison of the strain 297 and B31 RpoS DMC regulons identified two cohorts of RpoS-regulated genes. The first consists of highly conserved syntenic genes that are similarly regulated by RpoS in both strains and likely required for maintenance of B. burgdorferi sensu stricto strains in the wild. The second includes RpoS-regulated plasmid-encoded variable surface lipoproteins ospC, dbpA and members of the ospE/ospF/elp, mlp, revA, and Pfam54 paralogous gene families, all of which have evolved via inter- and intra-strain recombination. Thus, while the RpoN/RpoS pathway regulates a 'core' group of orthologous genes, diversity within RpoS regulons of different strains could be an important determinant of reservoir host range as well as spirochete virulence.
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Affiliation(s)
- Melissa J. Caimano
- Department of Medicine, UConn Health, Farmington, CT, United States,Department of Pediatrics, UConn Health, Farmington, CT, United States,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States,*Correspondence: Melissa J. Caimano,
| | | | - Alexia Belperron
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jialing Mao
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Kelly L. Hawley
- Department of Pediatrics, UConn Health, Farmington, CT, United States,Division of Infectious Diseases and Immunology, Connecticut Children’s Medical Center, Hartford, CT, United States
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, CT, United States
| | - Danielle E. Graham
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Christopher G. Earnhart
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Richard T. Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Linda K. Bockenstedt
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jon S. Blevins
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, CT, United States,Department of Pediatrics, UConn Health, Farmington, CT, United States,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States,Department of Genetics and Genome Science, UConn Health, Farmington, CT, United States,Department of Immunology, UConn Health, Farmington, CT, United States
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39
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Jutras BL, Savage CR, Arnold WK, Lethbridge KG, Carroll DW, Tilly K, Bestor A, Zhu H, Seshu J, Zückert WR, Stewart PE, Rosa PA, Brissette CA, Stevenson B. The Lyme disease spirochete's BpuR DNA/RNA-binding protein is differentially expressed during the mammal-tick infectious cycle, which affects translation of the SodA superoxide dismutase. Mol Microbiol 2019; 112:973-991. [PMID: 31240776 PMCID: PMC6736767 DOI: 10.1111/mmi.14336] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2019] [Indexed: 12/24/2022]
Abstract
When the Lyme disease spirochete, Borrelia burgdorferi, transfers from a feeding tick into a human or other vertebrate host, the bacterium produces vertebrate‐specific proteins and represses factors needed for arthropod colonization. Previous studies determined that the B. burgdorferi BpuR protein binds to its own mRNA and autoregulates its translation, and also serves as co‐repressor of erp transcription. Here, we demonstrate that B. burgdorferi controls transcription of bpuR, expressing high levels of bpuR during tick colonization but significantly less during mammalian infection. The master regulator of chromosomal replication, DnaA, was found to bind specifically to a DNA sequence that overlaps the bpuR promoter. Cultured B. burgdorferi that were genetically manipulated to produce elevated levels of BpuR exhibited altered levels of several proteins, although BpuR did not impact mRNA levels. Among these was the SodA superoxide dismutase, which is essential for mammalian infection. BpuR bound to sodA mRNA in live B. burgdorferi, and a specific BpuR‐binding site was mapped 5′ of the sodA open reading frame. Recognition of posttranscriptional regulation of protein levels by BpuR adds another layer to our understanding of the B. burgdorferi regulome, and provides further evidence that bacterial protein levels do not always correlate directly with mRNA levels.
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Affiliation(s)
- Brandon L Jutras
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Christina R Savage
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, USA
| | - William K Arnold
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Kathryn G Lethbridge
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Dustin W Carroll
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Kit Tilly
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Aaron Bestor
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Janakiram Seshu
- Department of Biology, University of Texas at San Antonio, San Antonio, TX, USA
| | - Wolfram R Zückert
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Philip E Stewart
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Patricia A Rosa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Catherine A Brissette
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Brian Stevenson
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, USA.,Department of Entomology, University of Kentucky, Lexington, KY, USA
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40
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Abstract
The spirochetes Borrelia (Borreliella) burgdorferi and Borrelia hermsii, the etiologic agents of Lyme disease and relapsing fever, respectively, cycle in nature between an arthropod vector and a vertebrate host. They have extraordinarily unusual genomes that are highly segmented and predominantly linear. The genetic analyses of Lyme disease spirochetes have become increasingly more sophisticated, while the age of genetic investigation in the relapsing fever spirochetes is just dawning. Molecular tools available for B. burgdorferi and related species range from simple selectable markers and gene reporters to state-of-the-art inducible gene expression systems that function in the animal model and high-throughput mutagenesis methodologies, despite nearly overwhelming experimental obstacles. This armamentarium has empowered borreliologists to build a formidable genetic understanding of the cellular physiology of the spirochete and the molecular pathogenesis of Lyme disease.
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Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA.
| | - D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA.
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41
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Rudenko N, Golovchenko M, Kybicova K, Vancova M. Metamorphoses of Lyme disease spirochetes: phenomenon of Borrelia persisters. Parasit Vectors 2019; 12:237. [PMID: 31097026 PMCID: PMC6521364 DOI: 10.1186/s13071-019-3495-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/09/2019] [Indexed: 12/22/2022] Open
Abstract
The survival of spirochetes from the Borrelia burgdorferi (sensu lato) complex in a hostile environment is achieved by the regulation of differential gene expression in response to changes in temperature, salts, nutrient content, acidity fluctuation, multiple host or vector dependent factors, and leads to the formation of dormant subpopulations of cells. From the other side, alterations in the level of gene expression in response to antibiotic pressure leads to the establishment of a persisters subpopulation. Both subpopulations represent the cells in different physiological states. “Dormancy” and “persistence” do share some similarities, e.g. both represent cells with low metabolic activity that can exist for extended periods without replication, both constitute populations with different gene expression profiles and both differ significantly from replicating forms of spirochetes. Persisters are elusive, present in low numbers, morphologically heterogeneous, multi-drug-tolerant cells that can change with the environment. The definition of “persisters” substituted the originally-used term “survivors”, referring to the small bacterial population of Staphylococcus that survived killing by penicillin. The phenomenon of persisters is present in almost all bacterial species; however, the reasons why Borrelia persisters form are poorly understood. Persisters can adopt varying sizes and shapes, changing from well-known forms to altered morphologies. They are capable of forming round bodies, L-form bacteria, microcolonies or biofilms-like aggregates, which remarkably change the response of Borrelia to hostile environments. Persisters remain viable despite aggressive antibiotic challenge and are able to reversibly convert into motile forms in a favorable growth environment. Persisters are present in significant numbers in biofilms, which has led to the explanation of biofilm tolerance to antibiotics. Considering that biofilms are associated with numerous chronic diseases through their resilient presence in the human body, it is not surprising that interest in persisting cells has consequently accelerated. Certain diseases caused by pathogenic bacteria (e.g. tuberculosis, syphilis or leprosy) are commonly chronic in nature and often recur despite antibiotic treatment. Three decades of basic and clinical research have not yet provided a definite answer to the question: is there a connection between persisting spirochetes and recurrence of Lyme disease in patients?
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Affiliation(s)
- Natalie Rudenko
- Biology Centre CAS, Institute of Parasitology, Branisovska 31, 37005, Ceske Budejovice, Czech Republic.
| | - Maryna Golovchenko
- Biology Centre CAS, Institute of Parasitology, Branisovska 31, 37005, Ceske Budejovice, Czech Republic
| | - Katerina Kybicova
- National Institute of Public Health, Srobarova 48, 100 42, Prague 10, Czech Republic
| | - Marie Vancova
- Biology Centre CAS, Institute of Parasitology, Branisovska 31, 37005, Ceske Budejovice, Czech Republic
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Borrelia burgdorferi bbk13 Is Critical for Spirochete Population Expansion in the Skin during Early Infection. Infect Immun 2019; 87:IAI.00887-18. [PMID: 30782856 DOI: 10.1128/iai.00887-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/08/2019] [Indexed: 12/31/2022] Open
Abstract
Lyme disease is caused by the spirochete Borrelia burgdorferi and is transmitted via the bite of an infected tick. B. burgdorferi enters the skin, disseminates via the bloodstream, and infects various distal tissues, leading to inflammatory sequelae, such as Lyme arthritis and Lyme carditis. B. burgdorferi linear plasmid 36 (lp36) is critical for mammalian infectivity; however, the full complement of genes on lp36 that contribute to this process remains unknown. Through a targeted mutagenesis screen of the genes on lp36, we identified a novel infectivity gene of unknown function, bbk13, which encodes an immunogenic, non-surface-exposed membrane protein that is important for efficient mammalian infection. Loss of bbk13 resulted in reduced spirochete loads in distal tissues in a mouse model of infection. Through a detailed analysis of B. burgdorferi infection kinetics, we discovered that bbk13 is important for promoting spirochete proliferation in the skin inoculation site. The attenuated ability of Δbbk13 spirochetes to proliferate in the inoculation site was followed by reduced numbers of B. burgdorferi spirochetes in the bloodstream and, ultimately, consistently reduced spirochete loads in distal tissues. Together, our data indicate that bbk13 contributes to disseminated infection by promoting spirochete proliferation in the early phase of infection in the skin. This work not only increases the understanding of the contribution of the genes on lp36 to B. burgdorferi infection but also begins to define the genetic basis for B. burgdorferi expansion in the skin during localized infection and highlights the influence of the early expansion of spirochetes in the skin on the outcome of infection.
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Casselli T, Crowley MA, Highland MA, Tourand Y, Bankhead T. A small intergenic region of lp17 is required for evasion of adaptive immunity and induction of pathology by the Lyme disease spirochete. Cell Microbiol 2019; 21:e13029. [PMID: 30945408 DOI: 10.1111/cmi.13029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/07/2019] [Accepted: 03/30/2019] [Indexed: 01/15/2023]
Abstract
The causative agent of Lyme disease, Borrelia burgdorferi, harbours a single linear chromosome and upwards of 23 linear and circular plasmids. Only a minority of these plasmids, including linear plasmid 17, are maintained with near-absolute fidelity during extended in vitro passage, and characterisation of any putative virulence determinants they encode has only recently begun. In this work, a mutant lacking a ~4.7 kb fragment of lp17 was studied. Colonisation of murine tissues by this lp17 mutant was significantly impaired, as was the ability to induce carditis and arthritis. The deficiency in tissue colonisation was alleviated in severe combined immunodeficient (SCID) mice, implicating a role for this plasmid region in adaptive immune evasion. Through genetic complementation, the mutant phenotype could be fully attributed to a 317 bp intergenic region that corresponds to the discontinued bbd07 ORF and upstream sequence. The intergenic region was found to be transcriptionally active, and mutant spirochetes lacking this region exhibited an overall difference in the antigenic profile during infection of an immunocompetent murine host. Overall, this study is the first to provide evidence for the involvement of lp17 in colonisation of joint and heart tissues, along with the associated pathologies caused by the Lyme disease spirochete.
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Affiliation(s)
- Timothy Casselli
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA
| | - Michael A Crowley
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA
| | - Margaret A Highland
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA.,Animal Disease Research Unit, USDA Agricultural Research Service, Pullman, Washington, USA
| | - Yvonne Tourand
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA
| | - Troy Bankhead
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA
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Mason C, Liu X, Prabhudeva S, Ouyang Z. The CXXC Motifs Are Essential for the Function of BosR in Borrelia burgdorferi. Front Cell Infect Microbiol 2019; 9:109. [PMID: 31041197 PMCID: PMC6476982 DOI: 10.3389/fcimb.2019.00109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/28/2019] [Indexed: 01/07/2023] Open
Abstract
BosR, a Fur family member, is essential for the pathogenesis of the Lyme disease pathogen, Borrelia burgdorferi. Unlike typical Fur proteins in which DNA binding represses gene expression, binding of BosR to the rpoS promoter directly activates rpoS transcription in B. burgdorferi. However, virtually nothing is known concerning potential structural features and amino acid residues of BosR that are important for protein function and virulence regulation in B. burgdorferi. Particularly, it remains unknown what structural motifs or residues of BosR coordinate Zn, although previous analyses have indicated that the function of BosR may depend on Zn. To address these information gaps, we herein introduced mutations into four conserved cysteine residues in two putative CXXC motifs of BosR. Our data showed that the ability of BosR to bind Zn was dramatically reduced when the CXXC motifs were mutated. Moreover, we found that the two CXXC motifs contributed to the ability of BosR to form dimers. By using a trans-complementation genetic approach, we additionally demonstrated that both CXXC motifs of BosR were essential for in vivo gene expression regulation. Mutation of any of the four cysteines abolished the transcriptional activation of rpoS. In contrast to wild type BosR, each mutant protein was incapable of binding the rpoS promoter in electrophoretic mobility shift assays. The combined data strongly support that the two CXXC motifs and four cysteines constitute the structural site essential for Zn-coordination, protein dimerization, and the unique regulatory activity of BosR.
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Affiliation(s)
- Charlotte Mason
- Department of Molecular Medicine, University of South Florida, Tampa, FL, United States
| | - Xiaoyan Liu
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Spoorthy Prabhudeva
- Department of Molecular Medicine, University of South Florida, Tampa, FL, United States
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL, United States
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DksA Controls the Response of the Lyme Disease Spirochete Borrelia burgdorferi to Starvation. J Bacteriol 2019; 201:JB.00582-18. [PMID: 30478087 PMCID: PMC6351744 DOI: 10.1128/jb.00582-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/20/2018] [Indexed: 12/17/2022] Open
Abstract
The pathogenic spirochete Borrelia burgdorferi senses and responds to changes in the environment, including changes in nutrient availability, throughout its enzootic cycle in Ixodes ticks and vertebrate hosts. This study examined the role of DnaK suppressor protein (DksA) in the transcriptional response of B. burgdorferi to starvation. Wild-type and dksA mutant B. burgdorferi strains were subjected to starvation by shifting cultures grown in rich complete medium, Barbour-Stoenner-Kelly II (BSK II) medium, to a defined mammalian tissue culture medium, RPMI 1640, for 6 h under microaerobic conditions (5% CO2, 3% O2). Microarray analyses of wild-type B. burgdorferi revealed that genes encoding flagellar components, ribosomal proteins, and DNA replication machinery were downregulated in response to starvation. DksA mediated transcriptomic responses to starvation in B. burgdorferi, as the dksA-deficient strain differentially expressed only 47 genes in response to starvation compared to the 500 genes differentially expressed in wild-type strains. Consistent with a role for DksA in the starvation response of B. burgdorferi, fewer CFU of dksA mutants were observed after prolonged starvation in RPMI 1640 medium than CFU of wild-type B. burgdorferi spirochetes. Transcriptomic analyses revealed a partial overlap between the DksA regulon and the regulon of RelBbu, the guanosine tetraphosphate and guanosine pentaphosphate [(p)ppGpp] synthetase that controls the stringent response; the DksA regulon also included many plasmid-borne genes. Additionally, the dksA mutant exhibited constitutively elevated (p)ppGpp levels compared to those of the wild-type strain, implying a regulatory relationship between DksA and (p)ppGpp. Together, these data indicate that DksA, along with (p)ppGpp, directs the stringent response to effect B. burgdorferi adaptation to its environment.IMPORTANCE The Lyme disease bacterium Borrelia burgdorferi survives diverse environmental challenges as it cycles between its tick vectors and various vertebrate hosts. B. burgdorferi must withstand prolonged periods of starvation while it resides in unfed Ixodes ticks. In this study, the regulatory protein DksA is shown to play a pivotal role controlling the transcriptional responses of B. burgdorferi to starvation. The results suggest that DksA gene regulatory activity impacts B. burgdorferi metabolism, virulence gene expression, and the ability of this bacterium to complete its natural life cycle.
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DNA Methylation by Restriction Modification Systems Affects the Global Transcriptome Profile in Borrelia burgdorferi. J Bacteriol 2018; 200:JB.00395-18. [PMID: 30249703 DOI: 10.1128/jb.00395-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 09/18/2018] [Indexed: 02/08/2023] Open
Abstract
Prokaryote restriction modification (RM) systems serve to protect bacteria from potentially detrimental foreign DNA. Recent evidence suggests that DNA methylation by the methyltransferase (MTase) components of RM systems can also have effects on transcriptome profiles. The type strain of the causative agent of Lyme disease, Borrelia burgdorferi B31, possesses two RM systems with N6-methyladenosine (m6A) MTase activity, which are encoded by the bbe02 gene located on linear plasmid lp25 and bbq67 on lp56. The specific recognition and/or methylation sequences had not been identified for either of these B. burgdorferi MTases, and it was not previously known whether these RM systems influence transcript levels. In the current study, single-molecule real-time sequencing was utilized to map genome-wide m6A sites and to identify consensus modified motifs in wild-type B. burgdorferi as well as MTase mutants lacking either the bbe02 gene alone or both bbe02 and bbq67 genes. Four novel conserved m6A motifs were identified and were fully attributable to the presence of specific MTases. Whole-genome transcriptome changes were observed in conjunction with the loss of MTase enzymes, indicating that DNA methylation by the RM systems has effects on gene expression. Genes with altered transcription in MTase mutants include those involved in vertebrate host colonization (e.g., rpoS regulon) and acquisition by/transmission from the tick vector (e.g., rrp1 and pdeB). The results of this study provide a comprehensive view of the DNA methylation pattern in B. burgdorferi, and the accompanying gene expression profiles add to the emerging body of research on RM systems and gene regulation in bacteria.IMPORTANCE Lyme disease is the most prevalent vector-borne disease in North America and is classified by the Centers for Disease Control and Prevention (CDC) as an emerging infectious disease with an expanding geographical area of occurrence. Previous studies have shown that the causative bacterium, Borrelia burgdorferi, methylates its genome using restriction modification systems that enable the distinction from foreign DNA. Although much research has focused on the regulation of gene expression in B. burgdorferi, the effect of DNA methylation on gene regulation has not been evaluated. The current study characterizes the patterns of DNA methylation by restriction modification systems in B. burgdorferi and evaluates the resulting effects on gene regulation in this important pathogen.
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Arnold WK, Savage CR, Lethbridge KG, Smith TC, Brissette CA, Seshu J, Stevenson B. Transcriptomic insights on the virulence-controlling CsrA, BadR, RpoN, and RpoS regulatory networks in the Lyme disease spirochete. PLoS One 2018; 13:e0203286. [PMID: 30161198 PMCID: PMC6117026 DOI: 10.1371/journal.pone.0203286] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 08/19/2018] [Indexed: 01/17/2023] Open
Abstract
Borrelia burgdorferi, the causative agent of Lyme disease, survives in nature through a cycle that alternates between ticks and vertebrates. To facilitate this defined lifestyle, B. burgdorferi has evolved a gene regulatory network that ensures transmission between those hosts, along with specific adaptations to niches within each host. Several regulatory proteins are known to be essential for the bacterium to complete these critical tasks, but interactions between regulators had not previously been investigated in detail, due to experimental uses of different strain backgrounds and growth conditions. To address that deficit in knowledge, the transcriptomic impacts of four critical regulatory proteins were examined in a uniform strain background. Pairs of mutants and their wild-type parent were grown simultaneously under a single, specific culture condition, permitting direct comparisons between the mutant strains. Transcriptomic analyses were strand-specific, and assayed both coding and noncoding RNAs. Intersection analyses identified regulatory overlaps between regulons, including transcripts involved in carbohydrate and polyamine metabolism. In addition, it was found that transcriptional units such as ospC and dbpBA, which were previously observed to be affected by alternative sigma factors, are transcribed by RNA polymerase using the housekeeping sigma factor, RpoD.
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Affiliation(s)
- William K. Arnold
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky School of Medicine, Lexington, KY, United States of America
| | - Christina R. Savage
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky School of Medicine, Lexington, KY, United States of America
| | - Kathryn G. Lethbridge
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky School of Medicine, Lexington, KY, United States of America
| | - Trever C. Smith
- Department of Biology, University of Texas at San Antonio, San Antonio, TX, United States of America
| | - Catherine A. Brissette
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, United States of America
| | - Janakiram Seshu
- Department of Biology, University of Texas at San Antonio, San Antonio, TX, United States of America
| | - Brian Stevenson
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky School of Medicine, Lexington, KY, United States of America
- Department of Entomology, University of Kentucky, Lexington, KY, United States of America
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Short-Chain Fatty Acids Alter Metabolic and Virulence Attributes of Borrelia burgdorferi. Infect Immun 2018; 86:IAI.00217-18. [PMID: 29891543 DOI: 10.1128/iai.00217-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 06/06/2018] [Indexed: 12/22/2022] Open
Abstract
Borrelia burgdorferi responds to a variety of host-derived factors and appropriately alters its gene expression for adaptation under different host-specific conditions. We previously showed that various levels of acetate, a short-chain fatty acid (SCFA), altered the protein profile of B. burgdorferi In this study, we determined the effects of other physiologically relevant SCFAs in the regulation of metabolic/virulence-associated proteins using mutant borrelial strains. No apparent increase in the synthesis of outer surface protein C (OspC) was noted when a carbon storage regulator A (csrA of B. burgdorferi, or csrABb ) mutant (mt) was propagated within dialysis membrane chambers implanted within rat peritoneal cavity, while the parental wild type (wt; B31-A3 strain) and csrABb cis-complemented strain (ct) had increased OspC with a reciprocal reduction in OspA levels. Growth rates of wt, mt, ct, 7D (csrABb mutant lacking 7 amino acids at the C terminus), and 8S (csrABb with site-specific changes altering its RNA-binding properties) borrelial strains were similar in the presence of acetate. Increased levels of propionate and butyrate reduced the growth rates of all strains tested, with mt and 8S exhibiting profound growth deficits at higher concentrations of propionate. Transcriptional levels of rpoS and ospC were elevated on supplementation of SCFAs compared to those of untreated spirochetes. Immunoblot analysis revealed elevated levels of RpoS, OspC, and DbpA with increased levels of SCFAs. Physiological levels of SCFAs prevalent in select human and rodent fluids were synergistic with mammalian host temperature and pH to increase the levels of aforementioned proteins, which could impact the colonization of B. burgdorferi during the mammalian phase of infection.
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Chen T, Xiang X, Xu H, Zhang X, Zhou B, Yang Y, Lou Y, Yang XF. LtpA, a CdnL-type CarD regulator, is important for the enzootic cycle of the Lyme disease pathogen. Emerg Microbes Infect 2018; 7:126. [PMID: 29985409 PMCID: PMC6037790 DOI: 10.1038/s41426-018-0122-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/31/2018] [Accepted: 06/04/2018] [Indexed: 01/12/2023]
Abstract
Little is known about how Borrelia burgdorferi, the Lyme disease pathogen, adapts and survives in the tick vector. We previously identified a bacterial CarD N-terminal-like (CdnL) protein, LtpA (BB0355), in B. burgdorferi that is preferably expressed at lower temperatures, which is a surrogate condition mimicking the tick portion of the enzootic cycle of B. burgdorferi. CdnL-family proteins, an emerging class of bacterial RNAP-interacting transcription factors, are essential for the viability of Mycobacterium tuberculosis and Myxococcus xanthus. Previous attempts to inactivate ltpA in B. burgdorferi have not been successful. In this study, we report the construction of a ltpA mutant in the infectious strain of B. burgdorferi, strain B31-5A4NP1. Unlike CdnL in M. tuberculosis and M. xanthus, LtpA is dispensable for the viability of B. burgdorferi. However, the ltpA mutant exhibits a reduced growth rate and a cold-sensitive phenotype. We demonstrate that LtpA positively regulates 16S rRNA expression, which contributes to the growth defects in the ltpA mutant. The ltpA mutant remains capable of infecting mice, albeit with delayed infection. Additionally, the ltpA mutant produces markedly reduced spirochetal loads in ticks and was not able to infect mice via tick infection. Overall, LtpA represents a novel regulator in the CdnL family that has an important role in the enzootic cycle of B. burgdorferi.
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Affiliation(s)
- Tong Chen
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, China.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Xuwu Xiang
- Department of Anesthesiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 310003, Hangzhou, China
| | - Haijun Xu
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 310058, Hangzhou, China
| | - Xuechao Zhang
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 310058, Hangzhou, China
| | - Bibi Zhou
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, China.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Youyun Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Yongliang Lou
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, China.
| | - X Frank Yang
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, China. .,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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50
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Drecktrah D, Hall LS, Rescheneder P, Lybecker M, Samuels DS. The Stringent Response-Regulated sRNA Transcriptome of Borrelia burgdorferi. Front Cell Infect Microbiol 2018; 8:231. [PMID: 30027068 PMCID: PMC6041397 DOI: 10.3389/fcimb.2018.00231] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/19/2018] [Indexed: 12/12/2022] Open
Abstract
The Lyme disease spirochete Borrelia (Borreliella) burgdorferi must tolerate nutrient stress to persist in the tick phase of its enzootic life cycle. We previously found that the stringent response mediated by RelBbu globally regulates gene expression to facilitate persistence in the tick vector. Here, we show that RelBbu regulates the expression of a swath of small RNAs (sRNA), affecting 36% of previously identified sRNAs in B. burgdorferi. This is the first sRNA regulatory mechanism identified in any spirochete. Threefold more sRNAs were RelBbu-upregulated than downregulated during nutrient stress and included antisense, intergenic and 5′ untranslated region sRNAs. RelBbu-regulated sRNAs associated with genes known to be important for host infection (bosR and dhhp) as well as persistence in the tick (glpF and hk1) were identified, suggesting potential mechanisms for post-transcriptional regulation of gene expression.
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Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Laura S Hall
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Philipp Rescheneder
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories, Medical University of Vienna, Vienna, Austria
| | - Meghan Lybecker
- Department of Biology, University of Colorado, Colorado Springs, CO, United States
| | - D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT, United States.,Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, United States
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