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Groshong AM, Gibbons NE, Moore BP, Bellamy WT, Blevins JS. The plasmid-encoded members of paralogous gene family 52 are dispensable to the enzootic cycle of Borrelia burgdorferi. Infect Immun 2024:e0021424. [PMID: 39120148 DOI: 10.1128/iai.00214-24] [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: 05/15/2024] [Accepted: 06/25/2024] [Indexed: 08/10/2024] Open
Abstract
Lyme disease, the leading vector-borne disease in the United States and Europe, develops after infection with Borrelia burgdorferi sensu lato bacteria. Transmission of the spirochete from the tick vector to a vertebrate host requires global changes in gene expression that are controlled, in part, by the Rrp2/RpoN/RpoS alternative sigma factor cascade. Transcriptional studies defining the B. burgdorferi RpoS regulon have suggested that RpoS activates the transcription of paralogous family 52 (PFam52) genes. In strain B31, PFam52 genes (bbi42, bbk53, and bbq03) encode a set of conserved hypothetical proteins with >89% amino acid identity that are predicted to be surface-localized. Extensive homology among members of paralogous families complicates studies of protein contributions to pathogenicity as the potential for functional redundancy will obfuscate findings. Using a sequential mutagenesis approach, we generated clones expressing a single PFam52 paralog, as well as a strain deficient in all three. The single paralog expressing strains were used to confirm BBI42, BBK53, and BBQ03 surface localization and RpoS regulation. Surprisingly, the PFam52-deficient strain was able to infect mice and complete the enzootic cycle similar to the wild-type parental strain. Indeed, the presence of numerous pseudogenes that contain frameshifts or internal stop codons among the PFam52 genes suggests that they may be subjected to gene loss in B. burgdorferi's reduced genome. Alternatively, the lack of phenotype might reflect the limitations of the experimental mouse infection model.
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Affiliation(s)
- Ashley M Groshong
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Laboratory of Bacteriology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Nora E Gibbons
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Brendan P Moore
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - William T Bellamy
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jon S Blevins
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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Kumaresan V, Ingle TM, Kilgore N, Zhang G, Hermann BP, Seshu J. Cellular and transcriptome signatures unveiled by single-cell RNA-Seq following ex vivo infection of murine splenocytes with Borrelia burgdorferi. Front Immunol 2023; 14:1296580. [PMID: 38149246 PMCID: PMC10749944 DOI: 10.3389/fimmu.2023.1296580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 11/06/2023] [Indexed: 12/28/2023] Open
Abstract
Introduction Lyme disease, the most common tick-borne infectious disease in the US, is caused by a spirochetal pathogen Borrelia burgdorferi (Bb). Distinct host responses are observed in susceptible and resistant strains of inbred of mice following infection with Bb reflecting a subset of inflammatory responses observed in human Lyme disease. The advent of post-genomic methodologies and genomic data sets enables dissecting the host responses to advance therapeutic options for limiting the pathogen transmission and/or treatment of Lyme disease. Methods In this study, we used single-cell RNA-Seq analysis in conjunction with mouse genomics exploiting GFP-expressing Bb to sort GFP+ splenocytes and GFP- bystander cells to uncover novel molecular and cellular signatures that contribute to early stages of immune responses against Bb. Results These data decoded the heterogeneity of splenic neutrophils, macrophages, NK cells, B cells, and T cells in C3H/HeN mice in response to Bb infection. Increased mRNA abundance of apoptosis-related genes was observed in neutrophils and macrophages clustered from GFP+ splenocytes. Moreover, complement-mediated phagocytosis-related genes such as C1q and Ficolin were elevated in an inflammatory macrophage subset, suggesting upregulation of these genes during the interaction of macrophages with Bb-infected neutrophils. In addition, the role of DUSP1 in regulating the expression of Casp3 and pro-inflammatory cytokines Cxcl1, Cxcl2, Il1b, and Ccl5 in Bb-infected neutrophils were identified. Discussion These findings serve as a growing catalog of cell phenotypes/biomarkers among murine splenocytes that can be exploited for limiting spirochetal burden to limit the transmission of the agent of Lyme disease to humans via reservoir hosts.
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Affiliation(s)
- Venkatesh Kumaresan
- Department of Molecular Microbiology and Immunology, The University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Taylor MacMackin Ingle
- Department of Molecular Microbiology and Immunology, The University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Nathan Kilgore
- Department of Molecular Microbiology and Immunology, The University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Guoquan Zhang
- Department of Molecular Microbiology and Immunology, The University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Brian P. Hermann
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Janakiram Seshu
- Department of Molecular Microbiology and Immunology, The University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
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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: 8] [Impact Index Per Article: 8.0] [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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Borreliella burgdorferi Antimicrobial-Tolerant Persistence in Lyme Disease and Posttreatment Lyme Disease Syndromes. mBio 2022; 13:e0344021. [PMID: 35467428 PMCID: PMC9239140 DOI: 10.1128/mbio.03440-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The annual incidence of Lyme disease, caused by tick-transmitted Borreliella burgdorferi, is estimated to be at least 476,000 cases in the United States and many more worldwide. Ten to 20% of antimicrobial-treated Lyme disease patients display posttreatment Lyme disease syndrome (PTLDS), a clinical complication whose etiology and pathogenesis remain uncertain. Autoimmunity, cross-reactivity, molecular mimicry, coinfections, and borrelial tolerance to antimicrobials/persistence have been hypothesized and studied as potential causes of PTLDS. Studies of borrelial tolerance/persistence in vitro in response to antimicrobials and experimental studies in mice and nonhuman primates, taken together with clinical reports, have revealed that B. burgdorferi becomes tolerant to antimicrobials and may sometimes persist in animals and humans after the currently recommended antimicrobial treatment. Moreover, B. burgdorferi is pleomorphic and can generate viable-but-nonculturable bacteria, states also involved in antimicrobial tolerance. The multiple regulatory pathways and structural genes involved in mediating this tolerance to antimicrobials and environmental stressors by persistence might include the stringent (rel and dksA) and host adaptation (rpoS) responses, sugar metabolism (glpD), and polypeptide transporters (opp). Application of this recently reported knowledge to clinical studies can be expected to clarify the potential role of bacterial antibacterial tolerance/persistence in Lyme disease and PTLDS.
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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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Zhu D, Wang S, Sun X. FliW and CsrA Govern Flagellin (FliC) Synthesis and Play Pleiotropic Roles in Virulence and Physiology of Clostridioides difficile R20291. Front Microbiol 2021; 12:735616. [PMID: 34675903 PMCID: PMC8523840 DOI: 10.3389/fmicb.2021.735616] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/13/2021] [Indexed: 02/04/2023] Open
Abstract
Clostridioides difficile flagellin FliC is associated with toxin gene expression, bacterial colonization, and virulence, and is also involved in pleiotropic gene regulation during in vivo infection. However, how fliC expression is regulated in C. difficile remains unclear. In Bacillus subtilis, flagellin homeostasis and motility are coregulated by flagellar assembly factor (FliW), flagellin Hag (FliC homolog), and Carbon storage regulator A (CsrA), which is referred to as partner-switching mechanism “FliW-CsrA-Hag.” In this study, we characterized FliW and CsrA functions by deleting or overexpressing fliW, csrA, and fliW-csrA in C. difficile R20291. We showed that fliW deletion, csrA overexpression in R20291, and csrA complementation in R20291ΔWA (fliW-csrA codeletion mutant) dramatically decreased FliC production, but not fliC gene transcription. Suppression of fliC translation by csrA overexpression can be relieved mostly when fliW was coexpressed, and no significant difference in FliC production was detected when only fliW was complemented in R20291ΔWA. Further, loss of fliW led to increased biofilm formation, cell adhesion, toxin production, and pathogenicity in a mouse model of C. difficile infection (CDI), while fliW-csrA codeletion decreased toxin production and mortality in vivo. Our data suggest that CsrA negatively modulates fliC expression and FliW indirectly affects fliC expression through inhibition of CsrA post-transcriptional regulation. In light of “FliW-CsrA-Hag” switch coregulation mechanism reported in B. subtilis, our data also suggest that “FliW-CsrA-fliC/FliC” can regulate many facets of C. difficile R20291 pathogenicity. These findings further aid us in understanding the virulence regulation in C. difficile.
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Affiliation(s)
- Duolong Zhu
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Shaohui Wang
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Xingmin Sun
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
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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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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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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: 18] [Impact Index Per Article: 4.5] [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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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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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: 9] [Impact Index Per Article: 2.3] [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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13
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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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14
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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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15
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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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16
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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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17
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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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18
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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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19
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Borrelia Host Adaptation Protein (BadP) Is Required for the Colonization of a Mammalian Host by the Agent of Lyme Disease. Infect Immun 2018; 86:IAI.00057-18. [PMID: 29685985 DOI: 10.1128/iai.00057-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/17/2018] [Indexed: 11/20/2022] Open
Abstract
Borrelia burgdorferi, the agent of Lyme disease (LD), uses host-derived signals to modulate gene expression during the vector and mammalian phases of infection. Microarray analysis of mutants lacking the B orrelia host adaptation regulator (BadR) revealed the downregulation of genes encoding enzymes whose role in the pathophysiology of B. burgdorferi is unknown. Immunoblot analysis of the badR mutants confirmed reduced levels of these enzymes, and one of these enzymes, encoded by bb0086, shares homology to prokaryotic magnesium chelatase and Lon-type proteases. The BB0086 levels in B. burgdorferi were higher under conditions mimicking those in fed ticks. Mutants lacking bb0086 had no apparent in vitro growth defect but were incapable of colonizing immunocompetent C3H/HeN or immunodeficient SCID mice. Immunoblot analysis revealed reduced levels of proteins critical for the adaptation of B. burgdorferi to the mammalian host, such as OspC, DbpA, and BBK32. Both RpoS and BosR, key regulators of gene expression in B. burgdorferi, were downregulated in the bb0086 mutants. Therefore, we designated BB0086 the B orrelia host adaptation protein (BadP). Unlike badP mutants, the control strains established infection in C3H/HeN mice at 4 days postinfection, indicating an early colonization defect in mutants due to reduced levels of the lipoproteins/regulators critical for initial stages of infection. However, badP mutants survived within dialysis membrane chambers (DMCs) implanted within the rat peritoneal cavity but, unlike the control strains, did not display complete switching of OspA to OspC, suggesting incomplete adaptation to the mammalian phase of infection. These findings have opened a novel regulatory mechanism which impacts the virulence potential of B burgdorferi.
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20
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Abstract
Bioinformatic approaches and a large volume of prokaryotic genome sequences have enabled rapid identification of regulatory proteins with features to bind DNA or RNA in a given prokaryote. However, biological relevance of these regulatory proteins requires methods to rapidly purify and determine their binding properties within the physiological context or life style of the organism. Here, we describe the experimental approaches to determine the nucleic acid binding properties of regulatory proteins of Borrelia burgdorferi using Borrelia host-adaptation Re.3gulator (BadR-a DNA binding protein) and Carbon storage regulators A of B. b urgdorferi (CsrABb-an RNA binding protein) as examples. Best laboratory practices associated with overexpression/purification of recombinant borrelial proteins, synthesis of target nucleic acid sequences, and electrophoretic mobility assays to assess the protein/nucleic acid interactions are described. The methods described are intended to facilitate empirical assessment of the binding affinity, co-factor requirements, quality of the interacting partners, and readily modifiable assay conditions to assess the binding properties to define known and unknown regulatory properties of nucleic acid binding proteins of B. burgdorferi.
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21
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Brock CM, Bañó-Polo M, Garcia-Murria MJ, Mingarro I, Esteve-Gasent M. Characterization of the inner membrane protein BB0173 from Borrelia burgdorferi. BMC Microbiol 2017; 17:219. [PMID: 29166863 PMCID: PMC5700661 DOI: 10.1186/s12866-017-1127-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 11/15/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The bacterial spirochete Borrelia burgdorferi is the causative agent of the most commonly reported arthropod-borne illness in the United States, Lyme disease. A family of proteins containing von Willebrand Factor A (VWFA) domains adjacent to a MoxR AAA+ ATPase have been found to be highly conserved in the genus Borrelia. Previously, a VWFA domain containing protein of B. burgdorferi, BB0172, was determined to be an outer membrane protein capable of binding integrin α3β1. In this study, the characterization of a new VWFA domain containing membrane protein, BB0173, is evaluated in order to define the location and topology of this multi-spanning membrane protein. In addition, functional predictions are made. RESULTS Our results show that BB0173, in contrast to BB0172, is an inner membrane protein, in which the VWFA domain is exposed to the periplasmic space. Further, BB0173 was predicted to have an aerotolerance regulator domain, and expression of BB0173 and the surrounding genes was evaluated under aerobic and microaerophilic conditions, revealing that these genes are downregulated under aerobic conditions. Since the VWFA domain containing proteins of B. burgdorferi are highly conserved, they are likely required for survival of the pathogen through sensing diverse environmental oxygen conditions. CONCLUSIONS Presently, the complex mechanisms that B. burgdorferi uses to detect and respond to environmental changes are not completely understood. However, studying the mechanisms that allow B. burgdorferi to survive in the highly disparate environments of the tick vector and mammalian host could allow for the development of novel methods of preventing acquisition, survival, or transmission of the spirochete. In this regard, a putative membrane protein, BB0173, was characterized. BB0173 was found to be highly conserved across pathogenic Borrelia, and additionally contains several truly transmembrane domains, and a Bacteroides aerotolerance-like domain. The presence of these functional domains and the highly conserved nature of this protein, strongly suggests a required function of BB0173 in the survival of B. burgdorferi.
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Affiliation(s)
- Christina M Brock
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TAMU-4467, College Station, TX, 77843, USA.,Current affiliation: Department of Entomology, College of Agricultural and Life Sciences, Texas A&M University, College Station, USA
| | - Manuel Bañó-Polo
- Department of Biochemistry and Molecular Biology, Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Faculty of Biology, University of Valencia, E-46100, Burjassot, Valencia, Spain
| | - Maria J Garcia-Murria
- Department of Biochemistry and Molecular Biology, Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Faculty of Biology, University of Valencia, E-46100, Burjassot, Valencia, Spain
| | - Ismael Mingarro
- Department of Biochemistry and Molecular Biology, Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Faculty of Biology, University of Valencia, E-46100, Burjassot, Valencia, Spain
| | - Maria Esteve-Gasent
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TAMU-4467, College Station, TX, 77843, USA.
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22
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Aslam B, Nisar MA, Khurshid M, Farooq Salamat MK. Immune escape strategies of Borrelia burgdorferi. Future Microbiol 2017; 12:1219-1237. [PMID: 28972415 DOI: 10.2217/fmb-2017-0013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The borrelial resurge demonstrates that Borrelia burgdorferi is a persistent health problem. This spirochete is responsible for a global public health concern called Lyme disease. B. burgdorferi faces diverse environmental conditions of its vector and host during its life cycle. To circumvent the host immune system is a prominent feature of B. burgdorferi. To date, numerous studies have reported on the various mechanisms used by this pathogen to evade the host defense mechanisms. This current review attempts to consolidate this information to describe the immunological and molecular methods used by B. burgdorferi for its survival.
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Affiliation(s)
- Bilal Aslam
- Department of Microbiology, Government College University, Faisalabad, Pakistan
| | - Muhammad Atif Nisar
- Department of Microbiology, Government College University, Faisalabad, Pakistan
| | - Mohsin Khurshid
- Department of Microbiology, Government College University, Faisalabad, Pakistan.,College of Allied Health Professionals, Directorate of Medical Sciences, Government College University, Faisalabad, Pakistan
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23
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Spermine and Spermidine Alter Gene Expression and Antigenic Profile of Borrelia burgdorferi. Infect Immun 2017; 85:IAI.00684-16. [PMID: 28052993 DOI: 10.1128/iai.00684-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 12/16/2016] [Indexed: 12/28/2022] Open
Abstract
Borrelia burgdorferi, the agent of Lyme disease, responds to numerous host-derived signals to alter adaptive capabilities during its enzootic cycle in an arthropod vector and mammalian host. Molecular mechanisms that enable B. burgdorferi to detect, channel, and respond to these signals have become an intense area of study for developing strategies to limit transmission/infection. Bioinformatic analysis of the borrelial genome revealed the presence of polyamine transport components (PotA, PotB, PotC, and PotD), while homologs for polyamine biosynthesis were conspicuously absent. Although potABCD is cotranscribed, the level of PotA was elevated under in vitro growth conditions mimicking unfed ticks compared to the level in fed ticks, while the levels of PotD were similar under the aforementioned conditions in B. burgdorferi Among several polyamines and polyamine precursors, supplementation of spermine or spermidine in the borrelial growth medium induced synthesis of major regulators of gene expression in B. burgdorferi, such as RpoS and BosR, with a concomitant increase in proteins that contribute to colonization and survival of B. burgdorferi in the mammalian host. Short transcripts of rpoS were elevated in response to spermidine, which was correlated with increased protein levels of RpoS. Transcriptional analysis of rpoZ and B. burgdorferirel (relBbu ; bb0198) in the presence of spermidine revealed the interplay of multiple regulatory factors in B. burgdorferi gene expression. The effect of spermidine on the levels of select borrelial proteins was also influenced by serum factors. These studies suggest that multiple host-derived signals/nutrients and their transport systems contribute to B. burgdorferi adaptation during the vector and vertebrate host phases of infection.
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Regulation of Gene and Protein Expression in the Lyme Disease Spirochete. Curr Top Microbiol Immunol 2017; 415:83-112. [PMID: 29064060 DOI: 10.1007/82_2017_49] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The infectious cycle of Borrelia burgdorferi necessitates persistent infection of both vertebrates and ticks, and efficient means of transmission between those two very different types of hosts. The Lyme disease spirochete has evolved mechanisms to sense its location in the infectious cycle, and use that information to control production of the proteins and other factors required for each step. Numerous components of borrelial regulatory pathways have been characterized to date. Their effects are being pieced together, thereby providing glimpses into a complex web of cooperative and antagonistic interactions. In this chapter, we present a broad overview of B. burgdorferi gene and protein regulation during the natural infectious cycle, discussions of culture-based methods for elucidating regulatory mechanisms, and summaries of many of the known regulatory proteins and small molecules. We also highlight areas that are in need of substantially more research.
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Abstract
Borrelia burgdorferi, the spirochetal agent of Lyme disease, is a zoonotic pathogen that is maintained in a natural cycle that typically involves mammalian reservoir hosts and a tick vector of the Ixodes species. During each stage of the enzootic cycle, B. burgdorferi is exposed to environments that differ in temperature, pH, small molecules, and most important, nutrient sources. B. burgdorferi has a highly restricted metabolic capacity because it does not contain a tricarboxylic acid cycle, oxidative phosphorylation, or any pathways for de novo biosynthesis of carbohydrates, amino acids, or lipids. Thus, B. burgdorferi relies solely on glycolysis for ATP production and is completely dependent on the transport of nutrients and cofactors from extracellular sources. Herein, pathways for carbohydrate uptake and utilization in B. burgdorferi are described. Regulation of these pathways during the different phases of the enzootic cycle is discussed. In addition, a model for differential control of nutrient flux through the glycolytic pathway as the spirochete transits through the enzootic cycle is presented.
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Spirochetal motility and chemotaxis in the natural enzootic cycle and development of Lyme disease. Curr Opin Microbiol 2015; 28:106-13. [PMID: 26519910 DOI: 10.1016/j.mib.2015.09.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 09/07/2015] [Indexed: 11/21/2022]
Abstract
Two-thirds of all bacterial genomes sequenced to-date possess an organelle for locomotion, referred to as flagella, periplasmic flagella or type IV pili. These genomes may also contain a chemotaxis-signaling system which governs flagellar rotation, thus leading a coordinated function for motility. Motility and chemotaxis are often crucial for infection or disease process caused by pathogenic bacteria. Although motility-associated genes are well-characterized in some organisms, the highly orchestrated synthesis, regulation, and assembly of periplasmic flagella in spirochetes are just being delineated. Recent advances were fostered by development of unique genetic manipulations in spirochetes coupled with cutting-edge imaging techniques. These contemporary advances in understanding the role of spirochetal motility and chemotaxis in host persistence and disease development are highlighted in this review.
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Absence of sodA Increases the Levels of Oxidation of Key Metabolic Determinants of Borrelia burgdorferi. PLoS One 2015; 10:e0136707. [PMID: 26322513 PMCID: PMC4556403 DOI: 10.1371/journal.pone.0136707] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/07/2015] [Indexed: 11/20/2022] Open
Abstract
Borrelia burgdorferi, the causative agent of Lyme disease, alters its gene expression in response to environmental signals unique to its tick vector or vertebrate hosts. B. burgdorferi carries one superoxide dismutase gene (sodA) capable of controlling intracellular superoxide levels. Previously, sodA was shown to be essential for infection of B. burgdorferi in the C3H/HeN model of Lyme disease. We employed two-dimensional electrophoresis (2-DE) and immunoblot analysis with antibodies specific to carbonylated proteins to identify targets that were differentially oxidized in the soluble fractions of the sodA mutant compared to its isogenic parental control strain following treatment with an endogenous superoxide generator, methyl viologen (MV, paraquat). HPLC-ESI-MS/MS analysis of oxidized proteins revealed that several proteins of the glycolytic pathway (BB0057, BB0020, BB0348) exhibited increased carbonylation in the sodA mutant treated with MV. Levels of ATP and NAD/NADH were reduced in the sodA mutant compared with the parental strain following treatment with MV and could be attributed to increased levels of oxidation of proteins of the glycolytic pathway. In addition, a chaperone, HtpG (BB0560), and outer surface protein A (OspA, BBA15) were also observed to be oxidized in the sodA mutant. Immunoblot analysis revealed reduced levels of Outer surface protein C (OspC), Decorin binding protein A (DbpA), fibronectin binding protein (BBK32), RpoS and BosR in the sodA mutant compared to the control strains. Viable sodA mutant spirochetes could not be recovered from both gp91/phox-⁄- and iNOS deficient mice while borrelial DNA was detected in multiple tissues samples from infected mice at significantly lower levels compared to the parental strain. Taken together, these observations indicate that the increased oxidation of select borrelial determinants and reduced levels of critical pathogenesis-associated lipoproteins contribute to the in vivo deficit of the sodA mutant in the mouse model of Lyme disease. This study, utilizing the sodA mutant, has provided insights into adaptive capabilities critical for survival of B. burgdorferi in its hosts.
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Bugrysheva JV, Pappas CJ, Terekhova DA, Iyer R, Godfrey HP, Schwartz I, Cabello FC. Characterization of the RelBbu Regulon in Borrelia burgdorferi Reveals Modulation of Glycerol Metabolism by (p)ppGpp. PLoS One 2015; 10:e0118063. [PMID: 25688856 PMCID: PMC4331090 DOI: 10.1371/journal.pone.0118063] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 01/07/2015] [Indexed: 02/07/2023] Open
Abstract
The bacterial stringent response is triggered by deficiencies of available nutrients and other environmental stresses. It is mediated by 5'-triphosphate-guanosine-3'-diphosphate and 5'-diphosphate-guanosine-3'-diphosphate (collectively (p)ppGpp) and generates global changes in gene expression and metabolism that enable bacteria to adapt to and survive these challenges. Borrelia burgdorferi encounters multiple stressors in its cycling between ticks and mammals that could trigger the stringent response. We have previously shown that the B. burgdorferi stringent response is mediated by a single enzyme, RelBbu, with both (p)ppGpp synthase and hydrolase activities, and that a B. burgdorferi 297 relBbu null deletion mutant was defective in adapting to stationary phase, incapable of down-regulating synthesis of rRNA and could not infect mice. We have now used this deletion mutant and microarray analysis to identify genes comprising the rel regulon in B. burgdorferi cultured at 34°C, and found that transcription of genes involved in glycerol metabolism is induced by relBbu. Culture of the wild type parental strain, the relBbu deletion mutant and its complemented derivative at 34°C and 25°C in media containing glucose or glycerol as principal carbon sources revealed a growth defect in the mutant, most evident at the lower temperature. Transcriptional analysis of the glp operon for glycerol uptake and metabolism in these three strains confirmed that relBbu was necessary and sufficient to increase transcription of this operon in the presence of glycerol at both temperatures. These results confirm and extend previous findings regarding the stringent response in B. burgdorferi. They also demonstrate that the stringent response regulates glycerol metabolism in this organism and is likely crucial for its optimal growth in ticks.
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Affiliation(s)
- Julia V. Bugrysheva
- Department of Microbiology and Immunology, New York Medical College, Valhalla, New York, 10595, United States of America
| | - Christopher J. Pappas
- Department of Microbiology and Immunology, New York Medical College, Valhalla, New York, 10595, United States of America
| | - Darya A. Terekhova
- Department of Microbiology and Immunology, New York Medical College, Valhalla, New York, 10595, United States of America
| | - Radha Iyer
- Department of Microbiology and Immunology, New York Medical College, Valhalla, New York, 10595, United States of America
| | - Henry P. Godfrey
- Department of Pathology, New York Medical College, Valhalla, New York, 10595, United States of America
| | - Ira Schwartz
- Department of Microbiology and Immunology, New York Medical College, Valhalla, New York, 10595, United States of America
| | - Felipe C. Cabello
- Department of Microbiology and Immunology, New York Medical College, Valhalla, New York, 10595, United States of America
- * E-mail:
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Heroven AK, Böhme K, Dersch P. The Csr/Rsm system of Yersinia and related pathogens. RNA Biol 2014; 9:379-91. [DOI: 10.4161/rna.19333] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Groshong AM, Blevins JS. Insights into the biology of Borrelia burgdorferi gained through the application of molecular genetics. ADVANCES IN APPLIED MICROBIOLOGY 2014; 86:41-143. [PMID: 24377854 DOI: 10.1016/b978-0-12-800262-9.00002-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Borrelia burgdorferi, the vector-borne bacterium that causes Lyme disease, was first identified in 1982. It is known that much of the pathology associated with Lyme borreliosis is due to the spirochete's ability to infect, colonize, disseminate, and survive within the vertebrate host. Early studies aimed at defining the biological contributions of individual genes during infection and transmission were hindered by the lack of adequate tools and techniques for molecular genetic analysis of the spirochete. The development of genetic manipulation techniques, paired with elucidation and annotation of the B. burgdorferi genome sequence, has led to major advancements in our understanding of the virulence factors and the molecular events associated with Lyme disease. Since the dawn of this genetic era of Lyme research, genes required for vector or host adaptation have garnered significant attention and highlighted the central role that these components play in the enzootic cycle of this pathogen. This chapter covers the progress made in the Borrelia field since the application of mutagenesis techniques and how they have allowed researchers to begin ascribing roles to individual genes. Understanding the complex process of adaptation and survival as the spirochete cycles between the tick vector and vertebrate host will lead to the development of more effective diagnostic tools as well as identification of novel therapeutic and vaccine targets. In this chapter, the Borrelia genes are presented in the context of their general biological roles in global gene regulation, motility, cell processes, immune evasion, and colonization/dissemination.
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Affiliation(s)
- Ashley M Groshong
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jon S Blevins
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
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Ouyang Z, Zhou J, Norgard MV. Synthesis of RpoS is dependent on a putative enhancer binding protein Rrp2 in Borrelia burgdorferi. PLoS One 2014; 9:e96917. [PMID: 24810170 PMCID: PMC4014564 DOI: 10.1371/journal.pone.0096917] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 04/13/2014] [Indexed: 12/13/2022] Open
Abstract
The RpoN-RpoS regulatory pathway plays a central role in governing adaptive changes by B. burgdorferi when the pathogen shuttles between its tick vector and mammalian hosts. In general, transcriptional activation of bacterial RpoN (σ54)-dependent genes requires an enhancer binding protein. B. burgdorferi encodes the putative enhancer binding protein Rrp2. Previous studies have revealed that the expression of σ54-dependent rpoS was abolished in an rrp2 point mutant. However, direct evidence linking the production of Rrp2 in B. burgdorferi and the expression of rpoS has been lacking, primarily due to the inability to inactivate rrp2 via deletion or insertion mutagenesis. Herein we introduced a regulatable (IPTG-inducible) rrp2 expression shuttle plasmid into B. burgdorferi, and found that the controlled up-regulation of Rrp2 resulted in the induction of σ54-dependent rpoS expression. Moreover, we created an rrp2 conditional lethal mutant in virulent B. burgdorferi. By exploiting this conditional mutant, we were able to experimentally manipulate the temporal level of Rrp2 expression in B. burgdorferi, and examine its direct impact on activation of the RpoN-RpoS regulatory pathway. Our data revealed that the synthesis of RpoS was coincident with the IPTG-induced Rrp2 levels in B. burgdorferi. In addition, the synthesis of OspC, a lipoprotein required by B. burgdorferi to establish mammalian infection, was rescued in the rrp2 point mutant when RpoS production was restored, suggesting that Rrp2 influences ospC expression indirectly via its control over RpoS. These data demonstrate that Rrp2 is required for the synthesis of RpoS, presumably via its action as an enhancer binding protein for the activation of RpoN and subsequent transcription of rpoS in B. burgdorferi.
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Affiliation(s)
- Zhiming Ouyang
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Jianli Zhou
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michael V. Norgard
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
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Dulebohn DP, Hayes BM, Rosa PA. Global repression of host-associated genes of the Lyme disease spirochete through post-transcriptional modulation of the alternative sigma factor RpoS. PLoS One 2014; 9:e93141. [PMID: 24671196 PMCID: PMC3966842 DOI: 10.1371/journal.pone.0093141] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/28/2014] [Indexed: 11/18/2022] Open
Abstract
Borrelia burgdorferi, the agent of Lyme disease, is a vector-borne pathogen that transits between Ixodes ticks and vertebrate hosts. During the natural infectious cycle, spirochetes must globally adjust their transcriptome to survive in these dissimilar environments. One way B. burgdorferi accomplishes this is through the use of alternative sigma factors to direct transcription of specific genes. RpoS, one of only three sigma factors in B. burgdorferi, controls expression of genes required during tick-transmission and infection of the mammalian host. How spirochetes switch between different sigma factors during the infectious cycle has remained elusive. Here we establish a role for a novel protein, BBD18, in the regulation of the virulence-associated sigma factor RpoS. Constitutive expression of BBD18 repressed transcription of RpoS-dependent genes to levels equivalent to those observed in an rpoS mutant. Consistent with the global loss of RpoS-dependent transcripts, we were unable to detect RpoS protein. However, constitutive expression of BBD18 did not diminish the amount of rpoS transcript, indicating post-transcriptional regulation of RpoS by BBD18. Interestingly, BBD18-mediated repression of RpoS is independent of both the rpoS promoter and the 5’ untranslated region, suggesting a mechanism of protein destabilization rather than translational control. We propose that BBD18 is a novel regulator of RpoS and its activity likely represents a first step in the transition from an RpoS-ON to an RpoS-OFF state, when spirochetes transition from the host to the tick vector.
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Affiliation(s)
- Daniel P. Dulebohn
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
- * E-mail:
| | - Beth M. Hayes
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Patricia A. Rosa
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
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CsrA (BB0184) is not involved in activation of the RpoN-RpoS regulatory pathway in Borrelia burgdorferi. Infect Immun 2014; 82:1511-22. [PMID: 24452681 DOI: 10.1128/iai.01555-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Borrelia burgdorferi encodes a homologue of the bacterial carbon storage regulator A (CsrA). Recently, it was reported that CsrA contributes to B. burgdorferi infectivity and is required for the activation of the central RpoN-RpoS regulatory pathway. However, many questions concerning the function of CsrA in B. burgdorferi gene regulation remain unanswered. In particular, there are conflicting reports concerning the molecular details of how CsrA may modulate rpoS expression and, thus, how CsrA may influence the RpoN-RpoS pathway in B. burgdorferi. To address these key discrepancies, we examined the role of CsrA in differential gene expression in the Lyme disease spirochete. Upon engineering an inducible csrA expression system in B. burgdorferi, controlled hyperexpression of CsrA in a merodiploid strain did not significantly alter the protein and transcript levels of bosR, rpoS, and RpoS-dependent genes (such as ospC and dbpA). In addition, we constructed isogenic csrA mutants in two widely used infectious B. burgdorferi strains. When expression of bosR, rpoS, ospC, and dbpA was compared between the csrA mutants and their wild-type counterparts, no detectable differences were observed. Finally, animal studies indicated that the csrA mutants remained infectious for and virulent in mice. Analyses of B. burgdorferi gene expression in mouse tissues showed comparable levels of rpoS transcripts by the csrA mutants and the parental strains. Taken together, these results constitute compelling evidence that CsrA is not involved in activation of the RpoN-RpoS pathway and is dispensable for mammalian infectious processes carried out by B. burgdorferi.
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HrpA, an RNA helicase involved in RNA processing, is required for mouse infectivity and tick transmission of the Lyme disease spirochete. PLoS Pathog 2013; 9:e1003841. [PMID: 24367266 PMCID: PMC3868530 DOI: 10.1371/journal.ppat.1003841] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 11/04/2013] [Indexed: 11/19/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi must differentially express genes and proteins in order to survive in and transit between its tick vector and vertebrate reservoir. The putative DEAH-box RNA helicase, HrpA, has been recently identified as an addition to the spirochete's global regulatory machinery; using proteomic methods, we demonstrated that HrpA modulates the expression of at least 180 proteins. Although most bacteria encode an HrpA helicase, RNA helicase activity has never been demonstrated for HrpAs and the literature contains little information on the contribution of this protein to bacterial physiology or pathogenicity. In this work, we report that B. burgdorferi HrpA has RNA-stimulated ATPase activity and RNA helicase activity and that this enzyme is essential for both mammalian infectivity by syringe inoculation and tick transmission. Reduced infectivity of strains carrying mutations in the ATPase and RNA binding motif mutants suggests that full virulence expression requires both ATPase and coupled helicase activity. Microarray profiling revealed changes in RNA levels of two-fold, or less in an hrpA mutant versus wild-type, suggesting that the enzyme functions largely or exclusively at the post-transcriptional level. In this regard, northern blot analysis of selected gene products highly regulated by HrpA (bb0603 [p66], bba74, bb0241 [glpK], bb0242 and bb0243 [glpA]) suggests a role for HrpA in the processing and translation of transcripts. In addition to being the first demonstration of RNA helicase activity for a bacterial HrpA, our data indicate that the post-transcriptional regulatory functions of this enzyme are essential for maintenance of the Lyme disease spirochete's enzootic cycle.
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Jutras BL, Jones GS, Verma A, Brown NA, Antonicello AD, Chenail AM, Stevenson B. Posttranscriptional self-regulation by the Lyme disease bacterium's BpuR DNA/RNA-binding protein. J Bacteriol 2013; 195:4915-23. [PMID: 23974034 PMCID: PMC3807498 DOI: 10.1128/jb.00819-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/21/2013] [Indexed: 01/21/2023] Open
Abstract
Bacteria require explicit control over their proteomes in order to compete and survive in dynamic environments. The Lyme disease spirochete Borrelia burgdorferi undergoes substantial protein profile changes during its cycling between vector ticks and vertebrate hosts. In an effort to understand regulation of these transitions, we recently isolated and functionally characterized the borrelial nucleic acid-binding protein BpuR, a PUR domain-containing protein. We now report that this regulatory protein governs its own synthesis through direct interactions with bpuR mRNA. In vitro and in vivo techniques indicate that BpuR binds with high affinity and specificity to the 5' region of its message, thereby inhibiting translation. This negative feedback could permit the bacteria to fine-tune cellular BpuR concentrations. These data add to the understanding of this newly described class of prokaryotic DNA- and RNA-binding regulatory proteins.
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Affiliation(s)
| | - Grant S. Jones
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | | | - Nicholas A. Brown
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Alyssa D. Antonicello
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Alicia M. Chenail
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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Contributions of environmental signals and conserved residues to the functions of carbon storage regulator A of Borrelia burgdorferi. Infect Immun 2013; 81:2972-85. [PMID: 23753623 DOI: 10.1128/iai.00494-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Carbon storage regulator A of Borrelia burgdorferi (CsrABb) contributes to vertebrate host-specific adaptation by modulating activation of the Rrp2-RpoN-RpoS pathway and is critical for infectivity. We hypothesized that the functions of CsrABb are dependent on environmental signals and on select residues. We analyzed the phenotype of csrABb deletion and site-specific mutants to determine the conserved and pathogen-specific attributes of CsrABb. Levels of phosphate acetyltransferase (Pta) involved in conversion of acetyl phosphate to acetyl-coenzyme A (acetyl-CoA) and posttranscriptionally regulated by CsrABb in the csrABb mutant were reduced from or similar to those in the control strains under unfed- or fed-tick conditions, respectively. Increased levels of supplemental acetate restored vertebrate host-responsive determinants in the csrABb mutant to parental levels, indicating that both the levels of CsrABb and the acetyl phosphate and acetyl-CoA balance contribute to the activation of the Rrp2-RpoN-RpoS pathway. Site-specific replacement of 8 key residues of CsrABb (8S) with alanines resulted in increased levels of CsrABb and reduced levels of Pta and acetyl-CoA, while levels of RpoS, BosR, and other members of rpoS regulon were elevated. Truncation of 7 amino acids at the C terminus of CsrABb (7D) resulted in reduced csrABb transcripts and posttranscriptionally reduced levels of FliW located upstream of CsrABb. Electrophoretic mobility shift assays revealed increased binding of 8S mutant protein to the CsrA binding box upstream of pta compared to the parental and 7D truncated protein. Two CsrABb binding sites were also identified upstream of fliW within the flgK coding sequence. These observations reveal conserved and unique functions of CsrABb that regulate adaptive gene expression in B. burgdorferi.
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Kung F, Anguita J, Pal U. Borrelia burgdorferi and tick proteins supporting pathogen persistence in the vector. Future Microbiol 2013; 8:41-56. [PMID: 23252492 DOI: 10.2217/fmb.12.121] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Borrelia burgdorferi, a pathogen transmitted by Ixodes ticks, is responsible for a prevalent illness known as Lyme disease, and a vaccine for human use is unavailable. Recently, genome sequences of several B. burgdorferi strains and Ixodes scapularis ticks have been determined. In addition, remarkable progress has been made in developing molecular genetic tools to study the pathogen and vector, including their intricate relationship. These developments are helping unravel the mechanisms by which Lyme disease pathogens survive in a complex enzootic infection cycle. Notable discoveries have already contributed to understanding the spirochete gene regulation accounting for the temporal and spatial expression of B. burgdorferi genes during distinct phases of the lifecycle. A number of pathogen and vector gene products have also been identified that contribute to microbial virulence and/or persistence. These research directions will enrich our knowledge of vector-borne infections and contribute towards the development of preventative strategies against Lyme disease.
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Affiliation(s)
- Faith Kung
- Department of Veterinary Medicine & Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA
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Abstract
Borrelia burgdorferi, the causative agent of Lyme disease, must adapt to two diverse niches, an arthropod vector and a mammalian host. RpoS, an alternative sigma factor, plays a central role in spirochetal adaptation to the mammalian host by governing expression of many genes important for mammalian infection. B. burgdorferi is known to be unique in metal utilization, and little is known of the role of biologically available metals in B. burgdorferi. Here, we identified two transition metal ions, manganese (Mn(2+)) and zinc (Zn(2+)), that influenced regulation of RpoS. The intracellular Mn(2+) level fluctuated approximately 20-fold under different conditions and inversely correlated with levels of RpoS and the major virulence factor OspC. Furthermore, an increase in intracellular Mn(2+) repressed temperature-dependent induction of RpoS and OspC; this repression was overcome by an excess of Zn(2+). Conversely, a decrease of intracellular Mn(2+) by deletion of the Mn(2+) transporter gene, bmtA, resulted in elevated levels of RpoS and OspC. Mn(2+) affected RpoS through BosR, a Fur family homolog that is required for rpoS expression: elevated intracellular Mn(2+) levels greatly reduced the level of BosR protein but not the level of bosR mRNA. Thus, Mn(2+) and Zn(2+) appeared to be important in modulation of the RpoS pathway that is essential to the life cycle of the Lyme disease spirochete. This finding supports the emerging notion that transition metals such as Mn(2+) and Zn(2+) play a critical role in regulation of virulence in bacteria.
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BB0172, a Borrelia burgdorferi outer membrane protein that binds integrin α3β1. J Bacteriol 2013; 195:3320-30. [PMID: 23687274 DOI: 10.1128/jb.00187-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Lyme disease is a multisystemic disorder caused by Borrelia burgdorferi infection. Upon infection, some B. burgdorferi genes are upregulated, including members of the microbial surface components recognizing adhesive matrix molecule (MSCRAMM) protein family, which facilitate B. burgdorferi adherence to extracellular matrix components of the host. Comparative genome analysis has revealed a new family of B. burgdorferi proteins containing the von Willebrand factor A (vWFA) domain. In the present study, we characterized the expression and membrane association of the vWFA domain-containing protein BB0172 by using in vitro transcription/translation systems in the presence of microsomal membranes and with detergent phase separation assays. Our results showed evidence of BB0172 localization in the outer membrane, the orientation of the vWFA domain to the extracellular environment, and its function as a metal ion-dependent integrin-binding protein. This is the first report of a borrelial adhesin with a metal ion-dependent adhesion site (MIDAS) motif that is similar to those observed in eukaryotic integrins and has a similar function.
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Abstract
The Lyme disease spirochete, Borrelia burgdorferi, exists in a zoonotic cycle involving an arthropod tick and mammalian host. Dissemination of the organism within and between these hosts depends upon the spirochete's ability to traverse through complex tissues. Additionally, the spirochete outruns the host immune cells while migrating through the dermis, suggesting the importance of B. burgdorferi motility in evading host clearance. B. burgdorferi's periplasmic flagellar filaments are composed primarily of a major protein, FlaB, and minor protein, FlaA. By constructing a flaB mutant that is nonmotile, we investigated for the first time the absolute requirement for motility in the mouse-tick life cycle of B. burgdorferi. We found that whereas wild-type cells are motile and have a flat-wave morphology, mutant cells were nonmotile and rod shaped. These mutants were unable to establish infection in C3H/HeN mice via either needle injection or tick bite. In addition, these mutants had decreased viability in fed ticks. Our studies provide substantial evidence that the periplasmic flagella, and consequently motility, are critical not only for optimal survival in ticks but also for infection of the mammalian host by the arthropod tick vector.
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Miller CL, Karna SLR, Seshu J. Borrelia host adaptation Regulator (BadR) regulates rpoS to modulate host adaptation and virulence factors in Borrelia burgdorferi. Mol Microbiol 2013; 88:105-24. [PMID: 23387366 DOI: 10.1111/mmi.12171] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2013] [Indexed: 11/27/2022]
Abstract
The RpoS transcription factor of Borrelia burgdorferi is a 'gatekeeper' because it activates genes required for spirochaetes to transition from tick to vertebrate hosts. However, it remains unknown how RpoS becomes repressed to allow the spirochaetes to transition back from the vertebrate host to the tick vector. Here we show that a putative carbohydrate-responsive regulatory protein, designated BadR (Borrelia host adaptation Regulator), is a transcriptional repressor of rpoS. BadR levels are elevated in B. burgdorferi cultures grown under in vitro conditions mimicking unfed-ticks and badR-deficient strains are defective for growth under these same conditions. Microarray and immunoblot analyses of badR-deficient strains showed upregulation of rpoS and other factors important for virulence in vertebrate hosts, as well as downregulation of putative tick-specific determinants (e.g. linear plasmid 28-4 genes). DNA-binding assays revealed BadR binds to upstream regions of rpoS. Site-directed mutations in BadR and the presence of phosphorylated sugars affected BadR's binding to the rpoS promoters. badR-deficient B. burgdorferi were unable to colonize mice. Several putative tick-specific targets have been identified. Our study identified a novel regulator, BadR, and provides a link between nutritional environmental cues utilized by spirochaetes to adaptation to disparate conditions found in the tick and vertebrate hosts.
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Affiliation(s)
- Christine L Miller
- South Texas Center for Emerging Infectious Diseases, Center for Excellence in Infection Genomics and Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, USA
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Aguirre JD, Clark HM, McIlvin M, Vazquez C, Palmere SL, Grab DJ, Seshu J, Hart PJ, Saito M, Culotta VC. A manganese-rich environment supports superoxide dismutase activity in a Lyme disease pathogen, Borrelia burgdorferi. J Biol Chem 2013; 288:8468-8478. [PMID: 23376276 DOI: 10.1074/jbc.m112.433540] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Lyme disease pathogen Borrelia burgdorferi represents a novel organism in which to study metalloprotein biology in that this spirochete has uniquely evolved with no requirement for iron. Not only is iron low, but we show here that B. burgdorferi has the capacity to accumulate remarkably high levels of manganese. This high manganese is necessary to activate the SodA superoxide dismutase (SOD) essential for virulence. Using a metalloproteomic approach, we demonstrate that a bulk of B. burgdorferi SodA directly associates with manganese, and a smaller pool of inactive enzyme accumulates as apoprotein. Other metalloproteins may have similarly adapted to using manganese as co-factor, including the BB0366 aminopeptidase. Whereas B. burgdorferi SodA has evolved in a manganese-rich, iron-poor environment, the opposite is true for Mn-SODs of organisms such as Escherichia coli and bakers' yeast. These Mn-SODs still capture manganese in an iron-rich cell, and we tested whether the same is true for Borrelia SodA. When expressed in the iron-rich mitochondria of Saccharomyces cerevisiae, B. burgdorferi SodA was inactive. Activity was only possible when cells accumulated extremely high levels of manganese that exceeded cellular iron. Moreover, there was no evidence for iron inactivation of the SOD. B. burgdorferi SodA shows strong overall homology with other members of the Mn-SOD family, but computer-assisted modeling revealed some unusual features of the hydrogen bonding network near the enzyme's active site. The unique properties of B. burgdorferi SodA may represent adaptation to expression in the manganese-rich and iron-poor environment of the spirochete.
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Affiliation(s)
- J Dafhne Aguirre
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205
| | - Hillary M Clark
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205
| | - Matthew McIlvin
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Christine Vazquez
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205
| | - Shaina L Palmere
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205
| | - Dennis J Grab
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - J Seshu
- Department of Biology, University of Texas, San Antonio, Texas 78249
| | - P John Hart
- Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, Texas 78229; Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Mak Saito
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Valeria C Culotta
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205.
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Changes in bacterial growth rate govern expression of the Borrelia burgdorferi OspC and Erp infection-associated surface proteins. J Bacteriol 2012; 195:757-64. [PMID: 23222718 DOI: 10.1128/jb.01956-12] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Lyme disease spirochete controls production of its OspC and Erp outer surface proteins, repressing protein synthesis during colonization of vector ticks but increasing expression when those ticks feed on vertebrate hosts. Early studies found that the synthesis of OspC and Erps can be stimulated in culture by shifting the temperature from 23°C to 34°C, leading to a hypothesis that Borrelia burgdorferi senses environmental temperature to determine its location in the tick-mammal infectious cycle. However, borreliae cultured at 34°C divide several times faster than do those cultured at 23°C. We developed methods that disassociate bacterial growth rate and temperature, allowing a separate evaluation of each factor's impacts on B. burgdorferi gene and protein expression. Altogether, the data support a new paradigm that B. burgdorferi actually responds to changes in its own replication rate, not temperature per se, as the impetus to increase the expression of the OspC and Erp infection-associated proteins.
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Chan K, Awan M, Barthold SW, Parveen N. Comparative molecular analyses of Borrelia burgdorferi sensu stricto strains B31 and N40D10/E9 and determination of their pathogenicity. BMC Microbiol 2012; 12:157. [PMID: 22846633 PMCID: PMC3511255 DOI: 10.1186/1471-2180-12-157] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 06/11/2012] [Indexed: 11/24/2022] Open
Abstract
Background Lyme disease in the United States is caused primarily by B. burgdorferi sensu stricto while other species are also prevalent in Europe. Genetic techniques have identified several chromosomal and plasmid-borne regulatory and virulence factors involved in Lyme pathogenesis. B31 and N40 are two widely studied strains of B. burgdorferi, which belong to two different 16 S-23 S rRNA spacer types (RST) and outer surface protein C (OspC) allelic groups. However, the presence of several known virulence factors in N40 has not been investigated. This is the first comprehensive study that compared these two strains both in vitro and using the mouse model of infection. Results Phylogenetic analyses predict B31 to be more infectious. However, our studies here indicate that N40D10/E9 is more infectious than the B31 strain at lower doses of inoculation in the susceptible C3H mice. Based-upon a careful analyses of known adhesins of these strains, it is predicted that the absence of a known fibronectin-glycosaminoglycan binding adhesin, bbk32, in the N40 strain could at least partially be responsible for reduction in its binding to Vero cells in vitro. Nevertheless, this difference does not affect the infectivity of N40D10/E9 strain. The genes encoding known regulatory and virulence factors critical for pathogenesis were detected in both strains. Differences in the protein profiles of these B. burgdorferi strains in vitro suggest that the novel, differentially expressed molecules may affect infectivity of B. burgdorferi. Further exacerbation of these molecular differences in vivo could affect the pathogenesis of spirochete strains. Conclusion Based upon the studies here, it can be predicted that N40D10/E9 disseminated infection at lower doses may be enhanced by its lower binding to epithelial cells at the site of inoculation due to the absence of BBK32. We suggest that complete molecular analyses of virulence factors followed by their evaluation using the mouse infection model should form the basis of determining infectivity and pathogenicity of different strains rather than simple phylogenetic group analyses. This study further emphasizes a need to investigate multiple invasive strains of B. burgdorferi to fully appreciate the pathogenic mechanisms that contribute to Lyme disease manifestations.
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Affiliation(s)
- Kamfai Chan
- Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 225 Warren Street, Newark, NJ 07103-3535, USA
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Van Laar TA, Lin YH, Miller CL, Karna SLR, Chambers JP, Seshu J. Effect of levels of acetate on the mevalonate pathway of Borrelia burgdorferi. PLoS One 2012; 7:e38171. [PMID: 22675445 PMCID: PMC3364977 DOI: 10.1371/journal.pone.0038171] [Citation(s) in RCA: 42] [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: 03/07/2012] [Accepted: 05/01/2012] [Indexed: 01/09/2023] Open
Abstract
Borrelia burgdorferi, the agent of Lyme disease, is a spirochetal pathogen with limited metabolic capabilities that survives under highly disparate host-specific conditions. However, the borrelial genome encodes several proteins of the mevalonate pathway (MP) that utilizes acetyl-CoA as a substrate leading to intermediate metabolites critical for biogenesis of peptidoglycan and post-translational modifications of proteins. In this study, we analyzed the MP and contributions of acetate in modulation of adaptive responses in B. burgdorferi. Reverse-transcription PCR revealed that components of the MP are transcribed as individual open reading frames. Immunoblot analysis using monospecific sera confirmed synthesis of members of the MP in B. burgdorferi. The rate-limiting step of the MP is mediated by HMG-CoA reductase (HMGR) via conversion of HMG-CoA to mevalonate. Recombinant borrelial HMGR exhibited a K(m) value of 132 µM with a V(max) of 1.94 µmol NADPH oxidized minute(-1) (mg protein)(-1) and was inhibited by statins. Total protein lysates from two different infectious, clonal isolates of B. burgdorferi grown under conditions that mimicked fed-ticks (pH 6.8/37°C) exhibited increased levels of HMGR while other members of the MP were elevated under unfed-tick (pH 7.6/23°C) conditions. Increased extra-cellular acetate gave rise to elevated levels of MP proteins along with RpoS, CsrA(Bb) and their respective regulons responsible for mediating vertebrate host-specific adaptation. Both lactone and acid forms of two different statins inhibited growth of B. burgdorferi strain B31, while overexpression of HMGR was able to partially overcome that inhibition. In summary, these studies on MP and contributions of acetate to host-specific adaptation have helped identify potential metabolic targets that can be manipulated to reduce the incidence of Lyme disease.
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Affiliation(s)
- Tricia A. Van Laar
- South Texas Center for Emerging Infectious Diseases and Department of Biology, Center for Excellence in Infection Genomics and The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Ying-Han Lin
- South Texas Center for Emerging Infectious Diseases and Department of Biology, Center for Excellence in Infection Genomics and The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Christine L. Miller
- South Texas Center for Emerging Infectious Diseases and Department of Biology, Center for Excellence in Infection Genomics and The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - S. L. Rajasekhar Karna
- South Texas Center for Emerging Infectious Diseases and Department of Biology, Center for Excellence in Infection Genomics and The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - James P. Chambers
- South Texas Center for Emerging Infectious Diseases and Department of Biology, Center for Excellence in Infection Genomics and The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - J. Seshu
- South Texas Center for Emerging Infectious Diseases and Department of Biology, Center for Excellence in Infection Genomics and The University of Texas at San Antonio, San Antonio, Texas, United States of America
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Ouyang Z, Narasimhan S, Neelakanta G, Kumar M, Pal U, Fikrig E, Norgard MV. Activation of the RpoN-RpoS regulatory pathway during the enzootic life cycle of Borrelia burgdorferi. BMC Microbiol 2012; 12:44. [PMID: 22443136 PMCID: PMC3320556 DOI: 10.1186/1471-2180-12-44] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 03/23/2012] [Indexed: 11/16/2022] Open
Abstract
Background The maintenance of Borrelia burgdorferi in its complex tick-mammalian enzootic life cycle is dependent on the organism's adaptation to its diverse niches. To this end, the RpoN-RpoS regulatory pathway in B. burgdorferi plays a central role in microbial survival and Lyme disease pathogenesis by up- or down-regulating the expression of a number of virulence-associated outer membrane lipoproteins in response to key environmental stimuli. Whereas a number of studies have reported on the expression of RpoS and its target genes, a more comprehensive understanding of when activation of the RpoN-RpoS pathway occurs, and when induction of the pathway is most relevant to specific stage(s) in the life cycle of B. burgdorferi, has been lacking. Results Herein, we examined the expression of rpoS and key lipoprotein genes regulated by RpoS, including ospC, ospA, and dbpA, throughout the entire tick-mammal infectious cycle of B. burgdorferi. Our data revealed that transcription of rpoS, ospC, and dbpA is highly induced in nymphal ticks when taking a blood meal. The RpoN-RpoS pathway remains active during the mammalian infection phase, as indicated by the sustained transcription of rpoS and dbpA in B. burgdorferi within mouse tissues following borrelial dissemination. However, dbpA transcription levels in fed larvae and intermolt larvae suggested that an additional layer of control likely is involved in the expression of the dbpBA operon. Our results also provide further evidence for the downregulation of ospA expression during mammalian infection, and the repression of ospC at later phases of mammalian infection by B. burgdorferi. Conclusion Our study demonstrates that the RpoN-RpoS regulatory pathway is initially activated during the tick transmission of B. burgdorferi to its mammalian host, and is sustained during mammalian infection.
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Affiliation(s)
- Zhiming Ouyang
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Abstract
Borrelia burgdorferi, the spirochete that causes Lyme disease, is maintained in nature via an enzootic cycle that comprises a tick vector and a vertebrate host. Transmission from the tick to the mammal, acquisition from the mammal back to the tick, and adaptation to the two disparate environments require sensing signals and responding by regulating programs of gene expression. The molecular mechanisms utilized to effect these lifestyle changes have begun to be elucidated and feature an alternative sigma factor cascade in which RpoN (σ(54)) and RpoS (σ(S)) globally control the genes required for the different phases of the enzootic cycle. The RpoN-RpoS pathway is surprisingly complex, entailing Rrp2, an unusual enhancer-binding protein and two-component regulatory system response regulator activated by acetyl phosphate; BosR, an unorthodox DNA-binding protein; DsrA(Bb), a small noncoding RNA; and Hfq and CsrA, two RNA-binding proteins. B. burgdorferi also has a c-di-GMP signaling system that regulates the tick side of the enzootic cycle and whose function is only beginning to be appreciated.
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Affiliation(s)
- D Scott Samuels
- Division of Biological Sciences and Biochemistry Program, The University of Montana, Missoula, Montana 59812, USA.
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Radolf JD, Caimano MJ, Stevenson B, Hu LT. Of ticks, mice and men: understanding the dual-host lifestyle of Lyme disease spirochaetes. Nat Rev Microbiol 2012; 10:87-99. [PMID: 22230951 PMCID: PMC3313462 DOI: 10.1038/nrmicro2714] [Citation(s) in RCA: 511] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In little more than 30 years, Lyme disease, which is caused by the spirochaete Borrelia burgdorferi, has risen from relative obscurity to become a global public health problem and a prototype of an emerging infection. During this period, there has been an extraordinary accumulation of knowledge on the phylogenetic diversity, molecular biology, genetics and host interactions of B. burgdorferi. In this Review, we integrate this large body of information into a cohesive picture of the molecular and cellular events that transpire as Lyme disease spirochaetes transit between their arthropod and vertebrate hosts during the enzootic cycle.
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Affiliation(s)
- Justin D Radolf
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
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Sze CW, Morado DR, Liu J, Charon NW, Xu H, Li C. Carbon storage regulator A (CsrA(Bb)) is a repressor of Borrelia burgdorferi flagellin protein FlaB. Mol Microbiol 2011; 82:851-64. [PMID: 21999436 DOI: 10.1111/j.1365-2958.2011.07853.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Lyme disease spirochete Borrelia burgdorferi lacks the transcriptional cascade control of flagellar protein synthesis common to other bacteria. Instead, it relies on a post-transcriptional mechanism to control its flagellar synthesis. The underlying mechanism of this control remains elusive. A recent study reported that the increased level of BB0184 (CsrA(Bb); a homologue of carbon storage regulator A) substantially inhibited the accumulation of FlaB, the major flagellin protein of B. burgdorferi. In this report, we deciphered the regulatory role of CsrA(Bb) on FlaB synthesis and the mechanism involved by analysing two mutants, csrA(Bb)(-) (a deletion mutant of csrA(Bb)) and csrA(Bb)(+) (a mutant conditionally overexpressing csrA(Bb)). We found that FlaB accumulation was significantly inhibited in csrA(Bb)(+) but was substantially increased in csrA(Bb)(-) . In contrast, the levels of other flagellar proteins remained unchanged. Cryo-electron tomography and immuno-fluorescence microscopic analyses revealed that the altered synthesis of CsrA(Bb) in these two mutants specifically affected flagellar filament length. The leader sequence of flaB transcript contains two conserved CsrA-binding sites, with one of these sites overlapping the Shine-Dalgarno sequence. We found that CsrA(Bb) bound to the flaB transcripts via these two binding sites, and this binding inhibited the synthesis of FlaB at the translational level. Taken together, our results indicate that CsrA(Bb) specifically regulates the periplasmic flagellar synthesis by inhibiting translation initiation of the flaB transcript.
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Affiliation(s)
- Ching Wooen Sze
- Department of Oral Biology, The State University of New York at Buffalo, New York 14214, USA
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Eggers CH, Caimano MJ, Malizia RA, Kariu T, Cusack B, Desrosiers DC, Hazlett KRO, Claiborne A, Pal U, Radolf JD. The coenzyme A disulphide reductase of Borrelia burgdorferi is important for rapid growth throughout the enzootic cycle and essential for infection of the mammalian host. Mol Microbiol 2011; 82:679-97. [PMID: 21923763 DOI: 10.1111/j.1365-2958.2011.07845.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In a microarray analysis of the RpoS regulon in mammalian host-adapted Borrelia burgdorferi, bb0728 (cdr) was found to be dually transcribed by the sigma factors σ(70) and RpoS. The cdr gene encodes a coenzyme A disulphide reductase (CoADR) that reduces CoA-disulphides to CoA in an NADH-dependent manner. Based on the abundance of CoA in B. burgdorferi and the biochemistry of the enzyme, CoADR has been proposed to play a role in the spirochaete's response to reactive oxygen species. To better understand the physiologic function(s) of BbCoADR, we generated a B. burgdorferi mutant in which the cdr gene was disrupted. RT-PCR and 5'-RACE analysis revealed that cdr and bb0729 are co-transcribed from a single transcriptional start site upstream of the bb0729 coding sequence; a shuttle vector containing the bb0729-cdr operon and upstream promoter element was used to complement the cdr mutant. Although the mutant was no more sensitive to hydrogen peroxide than its parent, it did exhibit increased sensitivity to high concentrations of t-butyl-hydroperoxide, an oxidizing compound that damages spirochetal membranes. Characterization of the mutant during standard (15% oxygen, 6% CO(2)) and anaerobic (< 1% O(2) , 9-13% CO(2)) cultivation at 37°C revealed a growth defect under both conditions that was particularly striking during anaerobiosis. The mutant was avirulent by needle inoculation and showed decreased survival in feeding nymphs, but displayed no survival defect in unfed flat nymphs. Based on these results, we propose that BbCoADR is necessary to maintain optimal redox ratios for CoA/CoA-disulphide and NAD(+) /NADH during periods of rapid replication throughout the enzootic cycle, to support thiol-disulphide homeostasis, and to indirectly protect the spirochaete against peroxide-mediated membrane damage; one or more of these functions are essential for infection of the mammalian host by B. burgdorferi.
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Affiliation(s)
- Christian H Eggers
- Department of Biomedical Sciences, Quinnipiac University, Hamden, CT 06518, USA.
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