1
|
Bourgeois JS, Hu LT. Hitchhiker's Guide to Borrelia burgdorferi. J Bacteriol 2024; 206:e0011624. [PMID: 39140751 PMCID: PMC11411949 DOI: 10.1128/jb.00116-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024] Open
Abstract
Don't Panic. In the nearly 50 years since the discovery of Lyme disease, Borrelia burgdorferi has emerged as an unlikely workhorse of microbiology. Interest in studying host-pathogen interactions fueled significant progress in making the fastidious microbe approachable in laboratory settings, including the development of culture methods, animal models, and genetic tools. By developing these systems, insight has been gained into how the microbe is able to survive its enzootic cycle and cause human disease. Here, we discuss the discovery of B. burgdorferi and its development as a model organism before diving into the critical lessons we have learned about B. burgdorferi biology at pivotal stages of its lifecycle: gene expression changes during the tick blood meal, colonization of a new vertebrate host, and developing a long-lasting infection in that vertebrate until a new tick feeds. Our goal is to highlight the advancements that have facilitated B. burgdorferi research and identify gaps in our current understanding of the microbe.
Collapse
Affiliation(s)
- Jeffrey S Bourgeois
- Department of Molecular Biology and Microbiology, Tufts University Lyme Disease Initiative, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Linden T Hu
- Department of Molecular Biology and Microbiology, Tufts University Lyme Disease Initiative, Tufts University School of Medicine, Boston, Massachusetts, USA
| |
Collapse
|
2
|
Jackson-Litteken CD, Guo W, Hogland BA, Ratliff CT, McFadden L, Fullerton MS, Voth DE, Rego ROM, Blevins JS. Development and validation of systems for genetic manipulation of the Old World tick-borne relapsing fever spirochete, Borrelia duttonii. PLoS Negl Trop Dis 2024; 18:e0012348. [PMID: 39038047 PMCID: PMC11293673 DOI: 10.1371/journal.pntd.0012348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 08/01/2024] [Accepted: 07/08/2024] [Indexed: 07/24/2024] Open
Abstract
Relapsing fever (RF), a vector-borne disease caused by Borrelia spp., is characterized by recurring febrile episodes due to repeated bouts of bacteremia. RF spirochetes can be geographically and phylogenetically divided into two distinct groups; Old World RF Borrelia (found in Africa, Asia, and Europe) and New World RF Borrelia (found in the Americas). While RF is a rarely reported disease in the Americas, RF is prevalent in endemic parts of Africa. Despite phylogenetic differences between Old World and New World RF Borrelia and higher incidence of disease associated with Old World RF spirochete infection, genetic manipulation has only been described in New World RF bacteria. Herein, we report the generation of genetic tools for use in the Old World RF spirochete, Borrelia duttonii. We describe methods for transformation and establish shuttle vector- and integration-based approaches for genetic complementation, creating green fluorescent protein (gfp)-expressing B. duttonii strains as a proof of principle. Allelic exchange mutagenesis was also used to inactivate a homolog of the Borrelia burgdorferi p66 gene, which encodes an important virulence factor, in B. duttonii and demonstrate that this mutant was attenuated in a murine model of RF. Finally, the B. duttonii p66 mutant was complemented using shuttle vector- and cis integration-based approaches. As expected, complemented p66 mutant strains were fully infectious, confirming that P66 is required for optimal mammalian infection. The genetic tools and techniques reported herein represent an important advancement in the study of RF Borrelia that allows for future characterization of virulence determinants and colonization factors important for the enzootic cycle of Old World RF spirochetes.
Collapse
Affiliation(s)
- Clay D. Jackson-Litteken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Wanfeng Guo
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Brandon A. Hogland
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - C. Tyler Ratliff
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - LeAnn McFadden
- Department of Biology, University of Arkansas at Little Rock, Little Rock, Arkansas, United States of America
| | - Marissa S. Fullerton
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Daniel E. Voth
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Ryan O. M. Rego
- Institute of Parasitology, Biology Centre CAS, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Jon S. Blevins
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| |
Collapse
|
3
|
Raghunandanan S, Priya R, Alanazi F, Lybecker MC, Schlax P, Yang X. A Fur family protein BosR is a novel RNA-binding protein that controls rpoS RNA stability in the Lyme disease pathogen. Nucleic Acids Res 2024; 52:5320-5335. [PMID: 38366569 PMCID: PMC11109971 DOI: 10.1093/nar/gkae114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 02/01/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
The σ54-σS sigma factor cascade plays a central role in regulating differential gene expression during the enzootic cycle of Borreliella burgdorferi, the Lyme disease pathogen. In this pathway, the primary transcription of rpoS (which encodes σS) is under the control of σ54 which is activated by a bacterial enhancer-binding protein (EBP), Rrp2. The σ54-dependent activation in B. burgdorferi has long been thought to be unique, requiring an additional factor, BosR, a homologue of classical Fur/PerR repressor/activator. However, how BosR is involved in this σ54-dependent activation remains unclear and perplexing. In this study, we demonstrate that BosR does not function as a regulator for rpoS transcriptional activation. Instead, it functions as a novel RNA-binding protein that governs the turnover rate of rpoS mRNA. We further show that BosR directly binds to the 5' untranslated region (UTR) of rpoS mRNA, and the binding region overlaps with a region required for rpoS mRNA degradation. Mutations within this 5'UTR region result in BosR-independent RpoS production. Collectively, these results uncover a novel role of Fur/PerR family regulators as RNA-binding proteins and redefine the paradigm of the σ54-σS pathway in B. burgdorferi.
Collapse
Affiliation(s)
- Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Raj Priya
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Fuad Alanazi
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 12372, Saudi Arabia
| | - Meghan C Lybecker
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Center for Disease Control and Prevention, Fort Collins, CO, USA
| | - Paula Jean Schlax
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - X Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| |
Collapse
|
4
|
Vance DJ, Basir S, Piazza CL, Willsey GG, Haque HME, Tremblay JM, Rudolph MJ, Muriuki B, Cavacini L, Weis DD, Shoemaker CB, Mantis NJ. Single-domain antibodies reveal unique borrelicidal epitopes on the Lyme disease vaccine antigen, outer surface protein A (OspA). Infect Immun 2024; 92:e0008424. [PMID: 38470113 PMCID: PMC11003225 DOI: 10.1128/iai.00084-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/13/2024] Open
Abstract
Camelid-derived, single-domain antibodies (VHHs) have proven to be extremely powerful tools in defining the antigenic landscape of immunologically heterogeneous surface proteins. In this report, we generated a phage-displayed VHH library directed against the candidate Lyme disease vaccine antigen, outer surface protein A (OspA). Two alpacas were immunized with recombinant OspA serotype 1 from Borrelia burgdorferi sensu stricto strain B31, in combination with the canine vaccine RECOMBITEK Lyme containing lipidated OspA. The phage library was subjected to two rounds of affinity enrichment ("panning") against recombinant OspA, yielding 21 unique VHHs within two epitope bins, as determined through competition enzyme linked immunosorbent assays (ELISAs) with a panel of OspA-specific human monoclonal antibodies. Epitope refinement was conducted by hydrogen exchange-mass spectrometry. Six of the monovalent VHHs were expressed as human IgG1-Fc fusion proteins and shown to have functional properties associated with protective human monoclonal antibodies, including B. burgdorferi agglutination, outer membrane damage, and complement-dependent borreliacidal activity. The VHHs displayed unique reactivity profiles with the seven OspA serotypes associated with B. burgdorferi genospecies in the United States and Europe consistent with there being unique epitopes across OspA serotypes that should be considered when designing and evaluating multivalent Lyme disease vaccines.
Collapse
Affiliation(s)
- David J. Vance
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - Saiful Basir
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - Carol Lyn Piazza
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
| | - Graham G. Willsey
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
| | | | - Jacque M. Tremblay
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
| | | | - Beatrice Muriuki
- Department of Medicine, University of Massachusetts Chan School of Medicine, Worcester, Massachusetts, USA
| | - Lisa Cavacini
- Department of Medicine, University of Massachusetts Chan School of Medicine, Worcester, Massachusetts, USA
| | - David D. Weis
- Department of Chemistry, The University of Kansas, Lawrence, Kansas, USA
| | - Charles B. Shoemaker
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
| | - Nicholas J. Mantis
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| |
Collapse
|
5
|
Faith DR, Kinnersley M, Brooks DM, Drecktrah D, Hall LS, Luo E, Santiago-Frangos A, Wachter J, Samuels DS, Secor PR. Characterization and genomic analysis of the Lyme disease spirochete bacteriophage ϕBB-1. PLoS Pathog 2024; 20:e1012122. [PMID: 38558079 PMCID: PMC11008901 DOI: 10.1371/journal.ppat.1012122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/11/2024] [Accepted: 03/13/2024] [Indexed: 04/04/2024] Open
Abstract
Lyme disease is a tick-borne infection caused by the spirochete Borrelia (Borreliella) burgdorferi. Borrelia species have highly fragmented genomes composed of a linear chromosome and a constellation of linear and circular plasmids some of which are required throughout the enzootic cycle. Included in this plasmid repertoire by almost all Lyme disease spirochetes are the 32-kb circular plasmid cp32 prophages that are capable of lytic replication to produce infectious virions called ϕBB-1. While the B. burgdorferi genome contains evidence of horizontal transfer, the mechanisms of gene transfer between strains remain unclear. While we know that ϕBB-1 transduces cp32 and shuttle vector DNA during in vitro cultivation, the extent of ϕBB-1 DNA transfer is not clear. Herein, we use proteomics and long-read sequencing to further characterize ϕBB-1 virions. Our studies identified the cp32 pac region and revealed that ϕBB-1 packages linear cp32s via a headful mechanism with preferential packaging of plasmids containing the cp32 pac region. Additionally, we find ϕBB-1 packages fragments of the linear chromosome and full-length plasmids including lp54, cp26, and others. Furthermore, sequencing of ϕBB-1 packaged DNA allowed us to resolve the covalently closed hairpin telomeres for the linear B. burgdorferi chromosome and most linear plasmids in strain CA-11.2A. Collectively, our results shed light on the biology of the ubiquitous ϕBB-1 phage and further implicates ϕBB-1 in the generalized transduction of diverse genes and the maintenance of genetic diversity in Lyme disease spirochetes.
Collapse
Affiliation(s)
- Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Margie Kinnersley
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Diane M. Brooks
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Eric Luo
- Vaccine and Infectious Disease Organization, Saskatoon, Canada
| | - Andrew Santiago-Frangos
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jenny Wachter
- Vaccine and Infectious Disease Organization, Saskatoon, Canada
| | - D. Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| |
Collapse
|
6
|
Hammond EM, Olsen KJ, Ram S, Tran GVV, Hall LS, Bradley JE, Lund FE, Samuels DS, Baumgarth N. Antigen-Specific CD4 T Cell and B Cell Responses to Borrelia burgdorferi. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 211:994-1005. [PMID: 37556156 PMCID: PMC10530202 DOI: 10.4049/jimmunol.2200890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 07/18/2023] [Indexed: 08/10/2023]
Abstract
Long-lived T-dependent B cell responses fail to develop during persistent infection of mice with Borrelia burgdorferi, the causative agent of Lyme disease, raising questions about the induction and/or functionality of anti-B. burgdorferi adaptive immune responses. Yet, a lack of reagents has limited investigations into B. burgdorferi-specific T and B cells. We attempted two approaches to track B. burgdorferi-induced CD4 T cells. First, a B. burgdorferi mutant was generated with an influenza hemagglutinin (HA) peptide, HA111-119, inserted into the B. burgdorferi arthritis-related protein (Arp) locus. Although this B. burgdorferi arp::HA strain remained infectious, peptide-specific TCR transgenic CD4 T cells in vitro, or adoptively transferred into B. burgdorferi arp::HA-infected BALB/c mice, did not clonally expand above those of recipients infected with the parental B. burgdorferi strain or a B. burgdorferi mutant containing an irrelevant peptide. Some expansion, however, occurred in B. burgdorferi arp::HA-infected BALB/c SCID mice. Second, a (to our knowledge) newly identified I-Ab-restricted CD4 T cell epitope, Arp152-166, was used to generate Arp MHC class II tetramers. Flow cytometry showed small numbers of Arp-specific CD4 T cells emerging in mice infected with B. burgdorferi but not with Arp-deficient Borrelia afzelii. Although up to 30% of Arp-specific CD4 T cells were ICOS+PD-1+CXCR5+BCL6+ T follicular helper cells, their numbers declined after day 12, before germinal centers (GCs) are prominent. Although some Arp-specific B cells, identified using fluorochrome-labeled rArp proteins, had the phenotype of GC B cells, their frequencies did not correlate with anti-Arp serum IgG. The data suggest a failure not in the induction, but in the maintenance of GC T follicular helper and/or B cells to B. burgdorferi.
Collapse
Affiliation(s)
- Elizabeth M. Hammond
- Graduate Group in Immunology, University of California Davis
- Center for Immunology and Infectious Diseases, University of California Davis
- Department of Pathology, Microbiology, and Immunology, University of California Davis
| | - Kimberly J. Olsen
- Center for Immunology and Infectious Diseases, University of California Davis
- Department of Pathology, Microbiology, and Immunology, University of California Davis
| | - Shivneel Ram
- Center for Immunology and Infectious Diseases, University of California Davis
| | - Giang Vu Vi Tran
- Center for Immunology and Infectious Diseases, University of California Davis
- Department of Pathology, Microbiology, and Immunology, University of California Davis
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana
| | - John E. Bradley
- Department of Microbiology, University of Alabama, Birmingham
| | - Frances E. Lund
- Department of Microbiology, University of Alabama, Birmingham
| | | | - Nicole Baumgarth
- Graduate Group in Immunology, University of California Davis
- Center for Immunology and Infectious Diseases, University of California Davis
- Department of Pathology, Microbiology, and Immunology, University of California Davis
- Department of Molecular Microbiology and Immunology and Department of Molecular and Comparative Pathobiology, Johns Hopkins University
| |
Collapse
|
7
|
Roy S, Booth CE, Powell-Pierce AD, Schulz AM, Skare JT, Garcia BL. Conformational dynamics of complement protease C1r inhibitor proteins from Lyme disease- and relapsing fever-causing spirochetes. J Biol Chem 2023; 299:104972. [PMID: 37380082 PMCID: PMC10413161 DOI: 10.1016/j.jbc.2023.104972] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/16/2023] [Accepted: 06/19/2023] [Indexed: 06/30/2023] Open
Abstract
Borrelial pathogens are vector-borne etiological agents known to cause Lyme disease, relapsing fever, and Borrelia miyamotoi disease. These spirochetes each encode several surface-localized lipoproteins that bind components of the human complement system to evade host immunity. One borrelial lipoprotein, BBK32, protects the Lyme disease spirochete from complement-mediated attack via an alpha helical C-terminal domain that interacts directly with the initiating protease of the classical complement pathway, C1r. In addition, the B. miyamotoi BBK32 orthologs FbpA and FbpB also inhibit C1r, albeit via distinct recognition mechanisms. The C1r-inhibitory activities of a third ortholog termed FbpC, which is found exclusively in relapsing fever-causing spirochetes, remains unknown. Here, we report the crystal structure of the C-terminal domain of Borrelia hermsii FbpC to a limiting resolution of 1.5 Å. We used surface plasmon resonance and assays of complement function to demonstrate that FbpC retains potent BBK32-like anticomplement activities. Based on the structure of FbpC, we hypothesized that conformational dynamics of the complement inhibitory domains of borrelial C1r inhibitors may differ. To test this, we utilized the crystal structures of the C-terminal domains of BBK32, FbpA, FbpB, and FbpC to carry out molecular dynamics simulations, which revealed borrelial C1r inhibitors adopt energetically favored open and closed states defined by two functionally critical regions. Taken together, these results advance our understanding of how protein dynamics contribute to the function of bacterial immune evasion proteins and reveal a surprising plasticity in the structures of borrelial C1r inhibitors.
Collapse
Affiliation(s)
- Sourav Roy
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Charles E Booth
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Alexandra D Powell-Pierce
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Bryan, Texas, USA
| | - Anna M Schulz
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Jon T Skare
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Bryan, Texas, USA.
| | - Brandon L Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
| |
Collapse
|
8
|
Ren Z, Takacs CN, Brandão HB, Jacobs-Wagner C, Wang X. Organization and replicon interactions within the highly segmented genome of Borrelia burgdorferi. PLoS Genet 2023; 19:e1010857. [PMID: 37494383 PMCID: PMC10406323 DOI: 10.1371/journal.pgen.1010857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/07/2023] [Accepted: 07/05/2023] [Indexed: 07/28/2023] Open
Abstract
Borrelia burgdorferi, a causative agent of Lyme disease, contains the most segmented bacterial genome known to date, with one linear chromosome and over twenty plasmids. How this unusually complex genome is organized, and whether and how the different replicons interact are unclear. We recently demonstrated that B. burgdorferi is polyploid and that the copies of the chromosome and plasmids are regularly spaced in each cell, which is critical for faithful segregation of the genome to daughter cells. Regular spacing of the chromosome is controlled by two separate partitioning systems that involve the protein pairs ParA/ParZ and ParB/Smc. Here, using chromosome conformation capture (Hi-C), we characterized the organization of the B. burgdorferi genome and the interactions between the replicons. We uncovered that although the linear chromosome lacks contacts between the two replication arms, the two telomeres are in frequent contact. Moreover, several plasmids specifically interact with the chromosome oriC region, and a subset of plasmids interact with each other more than with others. We found that Smc and the Smc-like MksB protein mediate long-range interactions on the chromosome, but they minimally affect plasmid-chromosome or plasmid-plasmid interactions. Finally, we found that disruption of the two partition systems leads to chromosome restructuring, correlating with the mis-positioning of chromosome oriC. Altogether, this study revealed the conformation of a complex genome and analyzed the contribution of the partition systems and SMC family proteins to this organization. This work expands the understanding of the organization and maintenance of multipartite bacterial genomes.
Collapse
Affiliation(s)
- Zhongqing Ren
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Constantin N. Takacs
- Department of Biology, Stanford University, Stanford, California, United States of America
- Sarafan ChEM-H Institute, Stanford University, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford, California, United States of America
| | - Hugo B. Brandão
- Illumina Inc., 5200 Illumina Way, San Diego, California, United States of America
| | - Christine Jacobs-Wagner
- Department of Biology, Stanford University, Stanford, California, United States of America
- Sarafan ChEM-H Institute, Stanford University, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford, California, United States of America
| | - Xindan Wang
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| |
Collapse
|
9
|
Van Gundy T, Patel D, Bowler BE, Rothfuss MT, Hall AJ, Davies C, Hall LS, Drecktrah D, Marconi RT, Samuels DS, Lybecker MC. c-di-GMP regulates activity of the PlzA RNA chaperone from the Lyme disease spirochete. Mol Microbiol 2023; 119:711-727. [PMID: 37086029 PMCID: PMC10330241 DOI: 10.1111/mmi.15066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/09/2023] [Accepted: 04/10/2023] [Indexed: 04/23/2023]
Abstract
PlzA is a c-di-GMP-binding protein crucial for adaptation of the Lyme disease spirochete Borrelia (Borreliella) burgdorferi during its enzootic life cycle. Unliganded apo-PlzA is important for vertebrate infection, while liganded holo-PlzA is important for survival in the tick; however, the biological function of PlzA has remained enigmatic. Here, we report that PlzA has RNA chaperone activity that is inhibited by c-di-GMP binding. Holo- and apo-PlzA bind RNA and accelerate RNA annealing, while only apo-PlzA can strand displace and unwind double-stranded RNA. Guided by the crystal structure of PlzA, we identified several key aromatic amino acids protruding from the N- and C-terminal domains that are required for RNA-binding and unwinding activity. Our findings illuminate c-di-GMP as a switch controlling the RNA chaperone activity of PlzA, and we propose that complex RNA-mediated modulatory mechanisms allow PlzA to regulate gene expression during both the vector and host phases of the B. burgdorferi life cycle.
Collapse
Affiliation(s)
- Taylor Van Gundy
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Center for Disease Control and Prevention, Fort Collins, CO 80521, USA
| | - Dhara Patel
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
| | - Bruce E. Bowler
- Department of Chemistry and Biochemistry, University of Montana, Missoula, MT 59812, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA
| | - Michael T. Rothfuss
- Department of Chemistry and Biochemistry, University of Montana, Missoula, MT 59812, USA
| | - Allie J. Hall
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Center for Disease Control and Prevention, Fort Collins, CO 80521, USA
| | - Christopher Davies
- Department of Biochemistry and Molecular Biology, University of Southern Alabama, Mobile, AL 36688, USA
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Richard T. Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
| | - D. Scott Samuels
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Meghan C. Lybecker
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Center for Disease Control and Prevention, Fort Collins, CO 80521, USA
- Department of Biology, University of Colorado, 1420 Austin Bluffs Parkway, Colorado Springs CO 80917, USA
| |
Collapse
|
10
|
Ren Z, Takacs CN, Brandão HB, Jacobs-Wagner C, Wang X. Organization and replicon interactions within the highly segmented genome of Borrelia burgdorferi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.19.532819. [PMID: 37066390 PMCID: PMC10103936 DOI: 10.1101/2023.03.19.532819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Borrelia burgdorferi , a causative agent of Lyme disease, contains the most segmented bacterial genome known to date, with one linear chromosome and over twenty plasmids. How this unusually complex genome is organized, and whether and how the different replicons interact are unclear. We recently demonstrated that B. burgdorferi is polyploid and that the copies of the chromosome and plasmids are regularly spaced in each cell, which is critical for faithful segregation of the genome to daughter cells. Regular spacing of the chromosome is controlled by two separate partitioning systems that involve the protein pairs ParA/ParZ and ParB/SMC. Here, using chromosome conformation capture (Hi-C), we characterized the organization of the B. burgdorferi genome and the interactions between the replicons. We uncovered that although the linear chromosome lacks contacts between the two replication arms, the two telomeres are in frequent contact. Moreover, several plasmids specifically interact with the chromosome oriC region, and a subset of plasmids interact with each other more than with others. We found that SMC and the SMC-like MksB protein mediate long-range interactions on the chromosome, but they minimally affect plasmid-chromosome or plasmid-plasmid interactions. Finally, we found that disruption of the two partition systems leads to chromosome restructuring, correlating with the mis-positioning of chromosome oriC . Altogether, this study revealed the conformation of a complex genome and analyzed the contribution of the partition systems and SMC family proteins to this organization. This work expands the understanding of the organization and maintenance of multipartite bacterial genomes.
Collapse
Affiliation(s)
- Zhongqing Ren
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Constantin N. Takacs
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- Sarafan ChEM-H Institute, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford, CA 94305, USA
| | | | - Christine Jacobs-Wagner
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- Sarafan ChEM-H Institute, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford, CA 94305, USA
- Corresponding authors: ;
| | - Xindan Wang
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Corresponding authors: ;
| |
Collapse
|
11
|
Thompson C, Waldron C, George S, Ouyang Z. Role of the Hypothetical Protein BB0563 during Borrelia burgdorferi Infection in Animals. Infect Immun 2023; 91:e0053922. [PMID: 36744894 PMCID: PMC10016080 DOI: 10.1128/iai.00539-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The alternative sigma factor RpoS in Borrelia burgdorferi, the etiological agent of Lyme disease, has long been postulated to regulate virulence-associated genes other than ospC and dbpA. Here, we demonstrate that bb0563, a gene encoding a hypothetical protein, is regulated by RpoS and contributes to the optimal infectivity of B. burgdorferi. When B. burgdorferi was exposed to environmental stimuli, bb0563 showed similar expression patterns as rpoS, ospC, and dbpA. Expression of bb0563 was significantly downregulated when rpoS was inactivated and was restored in the complemented strain. By using rapid amplification of cDNA ends (RACE) and luciferase reporter assays, a functional promoter was identified in the regulatory region upstream of bb0563. Gene expression from this promoter was drastically decreased in the rpoS mutant. We next investigated the role of bb0563 during animal infection. By using quantitative reverse transcription-PCR (RT-PCR), we found that bb0563 was highly expressed in mouse tissues during infection. We further created a bb0563-deficient mutant in a bioluminescent B. burgdorferi strain and examined infection dynamics using in vivo imaging. Relative to the parental and complemented strains, the mutant showed a delayed infection pattern and bacterial load was reduced. Another bb0563 deletion mutant was also created in the strain 297 background, and quantitative PCR (qPCR) analysis revealed a significantly lower spirochetal burden in tissue samples collected from animals infected with the mutant. In addition, localization studies indicate that BB0563 is not exposed on the cell surface but is associated with outer membrane. Taken together, these results suggest that bb0563 is required for optimal infectivity of B. burgdorferi during experimental infection.
Collapse
Affiliation(s)
- Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Connor Waldron
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Sierra George
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| |
Collapse
|
12
|
Roy S, Booth CE, Powell-Pierce AD, Schulz AM, Skare JT, Garcia BL. "Conformational dynamics of C1r inhibitor proteins from Lyme disease and relapsing fever spirochetes". BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.01.530473. [PMID: 36909632 PMCID: PMC10002728 DOI: 10.1101/2023.03.01.530473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Borrelial pathogens are vector-borne etiological agents of Lyme disease, relapsing fever, and Borrelia miyamotoi disease. These spirochetes each encode several surface-localized lipoproteins that bind to components of the human complement system. BBK32 is an example of a borrelial lipoprotein that protects the Lyme disease spirochete from complement-mediated attack. The complement inhibitory activity of BBK32 arises from an alpha helical C-terminal domain that interacts directly with the initiating protease of the classical pathway, C1r. Borrelia miyamotoi spirochetes encode BBK32 orthologs termed FbpA and FbpB, and these proteins also inhibit C1r, albeit via distinct recognition mechanisms. The C1r-inhibitory activities of a third ortholog termed FbpC, which is found exclusively in relapsing fever spirochetes, remains unknown. Here we report the crystal structure of the C-terminal domain of B. hermsii FbpC to a limiting resolution of 1.5 Å. Surface plasmon resonance studies and assays of complement function demonstrate that FbpC retains potent BBK32-like anti-complement activities. Based on the structure of FbpC, we hypothesized that conformational dynamics of the complement inhibitory domains of borrelial C1r inhibitors may differ. To test this, we utilized the crystal structures of the C-terminal domains of BBK32, FbpA, FbpB, and FbpC to carry out 1 µs molecular dynamics simulations, which revealed borrelial C1r inhibitors adopt energetically favored open and closed states defined by two functionally critical regions. This study advances our understanding of how protein dynamics contribute to the function of bacterial immune evasion proteins and reveals a surprising plasticity in the structures of borrelial C1r inhibitors.
Collapse
Affiliation(s)
- Sourav Roy
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Charles E. Booth
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Alexandra D. Powell-Pierce
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States of America
| | - Anna M. Schulz
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Jon T. Skare
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States of America
| | - Brandon L. Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| |
Collapse
|
13
|
Phelan JP, Bourgeois JS, McCarthy JE, Hu LT. A putative xanthine dehydrogenase is critical for Borrelia burgdorferi survival in ticks and mice. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001286. [PMID: 36748545 PMCID: PMC9993122 DOI: 10.1099/mic.0.001286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Borrelia burgdorferi is a pathogenic bacterium and the causative agent of Lyme disease. It is exposed to reactive oxygen species (ROS) in both the vertebrate and tick hosts. While some mechanisms by which B. burgdorferi ameliorates the effects of ROS exposure have been studied, there are likely other unknown mechanisms of ROS neutralization that contribute to virulence. Here, we follow up on a three gene cluster of unknown function, bb_0554, bb_0555, and bb_0556, that our prior unbiased transposon insertional sequencing studies implicated in both ROS survival and survival in Ixodes scapularis. We confirmed these findings through genetic knockout and provide evidence that these genes are co-transcribed as an operon to produce a xanthine dehydrogenase. In agreement with these results, we found that B. burgdorferi exposure to either uric acid (a product of xanthine dehydrogenase) or allopurinol (an inhibitor of xanthine dehydrogenase) could modulate sensitivity to ROS in a bb_0554-bb_0556 dependent manner. Together, this study identifies a previously uncharacterized three gene operon in B. burgdorferi as encoding a putative xanthine dehydrogenase critical for virulence. We propose renaming this locus xdhACB.
Collapse
Affiliation(s)
- James P Phelan
- Tufts University, Department of Molecular Biology and Microbiology, Boston, Massachusetts, USA.,Tufts University, Tufts Lyme Disease Initiative, Boston, Massachusetts, USA
| | - Jeffrey S Bourgeois
- Tufts University, Department of Molecular Biology and Microbiology, Boston, Massachusetts, USA.,Tufts University, Tufts Lyme Disease Initiative, Boston, Massachusetts, USA
| | - Julie E McCarthy
- Tufts University, Department of Molecular Biology and Microbiology, Boston, Massachusetts, USA.,Tufts University, Tufts Lyme Disease Initiative, Boston, Massachusetts, USA
| | - Linden T Hu
- Tufts University, Department of Molecular Biology and Microbiology, Boston, Massachusetts, USA.,Tufts University, Tufts Lyme Disease Initiative, Boston, Massachusetts, USA
| |
Collapse
|
14
|
Takacs CN, Wachter J, Xiang Y, Ren Z, Karaboja X, Scott M, Stoner MR, Irnov I, Jannetty N, Rosa PA, Wang X, Jacobs-Wagner C. Polyploidy, regular patterning of genome copies, and unusual control of DNA partitioning in the Lyme disease spirochete. Nat Commun 2022; 13:7173. [PMID: 36450725 PMCID: PMC9712426 DOI: 10.1038/s41467-022-34876-4] [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: 07/06/2022] [Accepted: 11/09/2022] [Indexed: 12/03/2022] Open
Abstract
Borrelia burgdorferi, the tick-transmitted spirochete agent of Lyme disease, has a highly segmented genome with a linear chromosome and various linear or circular plasmids. Here, by imaging several chromosomal loci and 16 distinct plasmids, we show that B. burgdorferi is polyploid during growth in culture and that the number of genome copies decreases during stationary phase. B. burgdorferi is also polyploid inside fed ticks and chromosome copies are regularly spaced along the spirochete's length in both growing cultures and ticks. This patterning involves the conserved DNA partitioning protein ParA whose localization is controlled by a potentially phage-derived protein, ParZ, instead of its usual partner ParB. ParZ binds its own coding region and acts as a centromere-binding protein. While ParA works with ParZ, ParB controls the localization of the condensin, SMC. Together, the ParA/ParZ and ParB/SMC pairs ensure faithful chromosome inheritance. Our findings underscore the plasticity of cellular functions, even those as fundamental as chromosome segregation.
Collapse
Affiliation(s)
- Constantin N Takacs
- Department of Biology, Stanford University, Palo Alto, CA, USA
- Sarafan ChEM-H Institute, Stanford University, Palo Alto, CA, USA
- The Howard Hughes Medical Institute, Palo Alto, CA, USA
| | - Jenny Wachter
- Laboratory of Bacteriology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
- Bacterial Vaccine Development Group, Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK, Canada
| | - Yingjie Xiang
- Department of Mechanical Engineering, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale West Campus, West Haven, CT, USA
| | - Zhongqing Ren
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Xheni Karaboja
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Molly Scott
- Microbial Sciences Institute, Yale West Campus, West Haven, CT, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
| | - Matthew R Stoner
- The Howard Hughes Medical Institute, Palo Alto, CA, USA
- Microbial Sciences Institute, Yale West Campus, West Haven, CT, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
| | - Irnov Irnov
- Department of Biology, Stanford University, Palo Alto, CA, USA
- Sarafan ChEM-H Institute, Stanford University, Palo Alto, CA, USA
- The Howard Hughes Medical Institute, Palo Alto, CA, USA
| | - Nicholas Jannetty
- The Howard Hughes Medical Institute, Palo Alto, CA, USA
- Microbial Sciences Institute, Yale West Campus, West Haven, CT, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
| | - Patricia A Rosa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Xindan Wang
- Department of Biology, Indiana University, Bloomington, IN, USA.
| | - Christine Jacobs-Wagner
- Department of Biology, Stanford University, Palo Alto, CA, USA.
- Sarafan ChEM-H Institute, Stanford University, Palo Alto, CA, USA.
- The Howard Hughes Medical Institute, Palo Alto, CA, USA.
| |
Collapse
|
15
|
Ramos D, Lasseter AG, Richards CL, Schwarz B, Ghosh S, Victoria B, Bosio CM, Gherardini FC, Jewett MW. Riboflavin salvage by Borrelia burgdorferi supports carbon metabolism and is essential for survival in the tick vector. Mol Microbiol 2022; 118:443-456. [PMID: 36054485 PMCID: PMC9588712 DOI: 10.1111/mmi.14977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 10/20/2023]
Abstract
The Lyme disease agent, Borrelia burgdorferi, harbors a significantly reduced genome and relies on the scavenging of critical nutrients from its tick and mammalian hosts for survival. Riboflavin salvage has been shown to be important for B. burgdorferi infection of mice, yet the contributions of riboflavin to B. burgdorferi metabolism and survival in the tick remain unknown. Using a targeted mass spectrometry approach, we confirmed the importance of bb0318, the putative ATPase component of an ABC-type riboflavin transporter, for riboflavin salvage and the production of FMN and FAD. This analysis further revealed that Δbb0318 B. burgdorferi displayed increased levels of glycerol 3-phosphate compared to the wild-type. The glycerol 3-phosphate dehydrogenase activity of GlpD was found to be FAD-dependent and the transcription and translation of glpD were significantly decreased in Δbb0318 B. burgdorferi. Finally, gene bb0318 was found to be important for maximal spirochete burden in unfed larvae and essential for survival in feeding ticks. Together, these data demonstrate the importance of riboflavin salvage for B. burgdorferi carbon metabolism and survival in ticks.
Collapse
Affiliation(s)
- Darlene Ramos
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Amanda G. Lasseter
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Crystal L. Richards
- Laboratory of Bacteriology, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Benjamin Schwarz
- Laboratory of Bacteriology, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Susmita Ghosh
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
- Tectonic Therapeutics, Watertown, Massachusetts, USA
| | - Berta Victoria
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Catharine M. Bosio
- Laboratory of Bacteriology, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Frank C. Gherardini
- Laboratory of Bacteriology, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Mollie W. Jewett
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| |
Collapse
|
16
|
Booth CE, Powell-Pierce AD, Skare JT, Garcia BL. Borrelia miyamotoi FbpA and FbpB Are Immunomodulatory Outer Surface Lipoproteins With Distinct Structures and Functions. Front Immunol 2022; 13:886733. [PMID: 35693799 PMCID: PMC9186069 DOI: 10.3389/fimmu.2022.886733] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/19/2022] [Indexed: 01/04/2023] Open
Abstract
Pathogens that traffic in the blood of their hosts must employ mechanisms to evade the host innate immune system, including the complement cascade. The Lyme disease spirochete, Borreliella burgdorferi, has evolved numerous outer membrane lipoproteins that interact directly with host proteins. Compared to Lyme disease-associated spirochetes, relatively little is known about how an emerging tick-borne spirochetal pathogen, Borrelia miyamotoi, utilizes surface lipoproteins to interact with a human host. B. burgdorferi expresses the multifunctional lipoprotein, BBK32, that inhibits the classical pathway of complement through interaction with the initiating protease C1r, and also interacts with fibronectin using a separate intrinsically disordered domain. B. miyamotoi encodes two separate bbk32 orthologs denoted fbpA and fbpB; however, the activities of these proteins are unknown. Here, we show that B. miyamotoi FbpA binds human fibronectin in a manner similar to B. burgdorferi BBK32, whereas FbpB does not. FbpA and FbpB both bind human complement C1r and protect a serum-sensitive B. burgdorferi strain from complement-mediated killing, but surprisingly, differ in their ability to recognize activated C1r versus zymogen states of C1r. To better understand the observed differences in C1r recognition and inhibition properties, high-resolution X-ray crystallography structures were solved of the C1r-binding regions of B. miyamotoi FbpA and FbpB at 1.9Å and 2.1Å, respectively. Collectively, these data suggest that FbpA and FbpB have partially overlapping functions but are functionally and structurally distinct. The data presented herein enhances our overall understanding of how bloodborne pathogens interact with fibronectin and modulate the complement system.
Collapse
Affiliation(s)
- Charles E Booth
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Alexandra D Powell-Pierce
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States
| | - Jon T Skare
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States
| | - Brandon L Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| |
Collapse
|
17
|
Castellanos M, Verhey TB, Goldstein M, Chaconas G. The Putative Endonuclease Activity of MutL Is Required for the Segmental Gene Conversion Events That Drive Antigenic Variation of the Lyme Disease Spirochete. Front Microbiol 2022; 13:888494. [PMID: 35663861 PMCID: PMC9159922 DOI: 10.3389/fmicb.2022.888494] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/18/2022] [Indexed: 11/30/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi, encodes an elaborate antigenic variation system that promotes the ongoing variation of a major surface lipoprotein, VlsE. Changes in VlsE are continual and always one step ahead of the host acquired immune system, which requires 1–2 weeks to generate specific antibodies. By the time this happens, new VlsE variants have arisen that escape immunosurveillance, providing an avenue for persistent infection. This antigenic variation system is driven by segmental gene conversion events that transfer information from a series of silent cassettes (vls2-16) to the expression locus, vlsE. The molecular details of this process remain elusive. Recombinational switching at vlsE is RecA-independent and the only required factor identified to date is the RuvAB branch migrase. In this work we have used next generation long-read sequencing to analyze the effect of several DNA replication/recombination/repair gene disruptions on the frequency of gene conversions at vlsE and report a requirement for the mismatch repair protein MutL. Site directed mutagenesis of mutL suggests that the putative MutL endonuclease activity is required for recombinational switching at vlsE. This is the first report of an unexpected essential role for MutL in a bacterial recombination system and expands the known function of this protein as well as our knowledge of the details of the novel recombinational switching mechanism for vlsE variation.
Collapse
Affiliation(s)
- Mildred Castellanos
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Theodore B. Verhey
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Madeleine Goldstein
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - George Chaconas
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- *Correspondence: George Chaconas,
| |
Collapse
|
18
|
Wong JK, Crowley MA, Bankhead T. Deletion of a Genetic Region of lp17 Affects Plasmid Copy Number in Borrelia burgdorferi. Front Cell Infect Microbiol 2022; 12:884171. [PMID: 35493747 PMCID: PMC9039534 DOI: 10.3389/fcimb.2022.884171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Borrelia burgdorferi, the Lyme disease pathogen, is maintained in its enzootic life cycle through complex gene regulatory pathways encoded on its uniquely fragmented genome. This genome consists of over 20 plasmids, and the regulatory mechanisms of plasmid maintenance and replication are largely unknown. The bbd21 gene, encoded on lp17 and a member of the paralogous family 32 proteins, was originally proposed to be a putative parA orthologue involved with plasmid partitioning; however, this function has not been confirmed to date. To determine the role of bbd21 in B. burgdorferi, we utilized targeted gene deletion and discovered bbd21 and bbd22 are co-transcribed. The effects of bbd21 and bbd22 deletion on plasmid copy number and mammalian infectivity were assessed. By qPCR, lp17 copy number did not differ amongst strains during mid-exponential and stationary growth phases. However, after in vitro passaging, the mutant strain demonstrated an 8-fold increase in lp17 copies, suggesting a cumulative defect in plasmid copy number regulation. Additionally, we compared lp17 copy number between in vitro and mammalian host-adapted conditions. Our findings showed 1) lp17 copy number was significantly different between these growth conditions for both the wild type and bbd21-bbd22 deletion mutant and 2) under mammalian host-adapted cultivation, the absence of bbd21-bbd22 resulted in significantly decreased copies of lp17. Murine infection studies using culture and qPCR demonstrated bbd21-bbd22 deletion resulted in a tissue colonization defect, particularly in the heart. Lastly, we showed bbd21 transcription appears to be independent of direct rpoS regulation based on similar expression levels in wild type and ΔrpoS. Altogether, our findings indicate the bbd21-bbd22 genetic region is involved with regulation of lp17 plasmid copy number. Furthermore, we propose the possibility that lp17 plasmid copy number is important for microbial pathogenesis by the Lyme disease spirochete.
Collapse
|
19
|
Drecktrah D, Hall LS, Crouse B, Schwarz B, Richards C, Bohrnsen E, Wulf M, Long B, Bailey J, Gherardini F, Bosio CM, Lybecker MC, Samuels DS. The glycerol-3-phosphate dehydrogenases GpsA and GlpD constitute the oxidoreductive metabolic linchpin for Lyme disease spirochete host infectivity and persistence in the tick. PLoS Pathog 2022; 18:e1010385. [PMID: 35255112 PMCID: PMC8929704 DOI: 10.1371/journal.ppat.1010385] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/17/2022] [Accepted: 02/18/2022] [Indexed: 12/18/2022] Open
Abstract
We have identified GpsA, a predicted glycerol-3-phosphate dehydrogenase, as a virulence factor in the Lyme disease spirochete Borrelia (Borreliella) burgdorferi: GpsA is essential for murine infection and crucial for persistence of the spirochete in the tick. B. burgdorferi has a limited biosynthetic and metabolic capacity; the linchpin connecting central carbohydrate and lipid metabolism is at the interconversion of glycerol-3-phosphate and dihydroxyacetone phosphate, catalyzed by GpsA and another glycerol-3-phosphate dehydrogenase, GlpD. Using a broad metabolomics approach, we found that GpsA serves as a dominant regulator of NADH and glycerol-3-phosphate levels in vitro, metabolic intermediates that reflect the cellular redox potential and serve as a precursor for lipid and lipoprotein biosynthesis, respectively. Additionally, GpsA was required for survival under nutrient stress, regulated overall reductase activity and controlled B. burgdorferi morphology in vitro. Furthermore, during in vitro nutrient stress, both glycerol and N-acetylglucosamine were bactericidal to B. burgdorferi in a GlpD-dependent manner. This study is also the first to identify a suppressor mutation in B. burgdorferi: a glpD deletion restored the wild-type phenotype to the pleiotropic gpsA mutant, including murine infectivity by needle inoculation at high doses, survival under nutrient stress, morphological changes and the metabolic imbalance of NADH and glycerol-3-phosphate. These results illustrate how basic metabolic functions that are dispensable for in vitro growth can be essential for in vivo infectivity of B. burgdorferi and may serve as attractive therapeutic targets. Lyme disease (borreliosis) is the most common tick-borne disease in the Northern hemisphere and its prevalence is increasing. Borrelia burgdorferi, the etiological agent of Lyme disease, is an enzootic pathogen that alternates between a tick vector and vertebrate host. Humans are considered an incidental host after transmission of B. burgdorferi following the bite of an infected tick. The mechanisms by which B. burgdorferi persists in the Ixodid tick, transmits to a vertebrate host and establishes infection are not well understood. Therefore, identifying virulence factors and uncovering the pathogenic strategies in the spirochete remain important to address the public health concerns of Lyme disease. In this study, we identify an enzyme involved in three-carbon metabolism, GpsA, as a new virulence factor with an effect on persistence in ticks. GpsA and GlpD, another enzyme, constitute a bidirectional metabolic node connecting lipid biosynthesis and glycolysis, which serves as the linchpin for regulating carbon utilization for B. burgdorferi throughout its enzootic cycle. Disruption of this node causes a lethal metabolic imbalance revealing a potential therapeutic target for the treatment of Lyme disease.
Collapse
Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
- * E-mail: (DD); (DSS)
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Bethany Crouse
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Benjamin Schwarz
- Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Crystal Richards
- Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Eric Bohrnsen
- Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Michael Wulf
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Bonnie Long
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Jessica Bailey
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Frank Gherardini
- Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Catharine M. Bosio
- Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Meghan C. Lybecker
- Department of Biology, University of Colorado, Colorado Springs, Colorado, United States of America
| | - D. Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, United States of America
- * E-mail: (DD); (DSS)
| |
Collapse
|
20
|
Garrigues RJ, Powell-Pierce AD, Hammel M, Skare JT, Garcia BL. A Structural Basis for Inhibition of the Complement Initiator Protease C1r by Lyme Disease Spirochetes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2021; 207:2856-2867. [PMID: 34759015 PMCID: PMC8612984 DOI: 10.4049/jimmunol.2100815] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 09/23/2021] [Indexed: 12/26/2022]
Abstract
Complement evasion is a hallmark of extracellular microbial pathogens such as Borrelia burgdorferi, the causative agent of Lyme disease. Lyme disease spirochetes express nearly a dozen outer surface lipoproteins that bind complement components and interfere with their native activities. Among these, BBK32 is unique in its selective inhibition of the classical pathway. BBK32 blocks activation of this pathway by selectively binding and inhibiting the C1r serine protease of the first component of complement, C1. To understand the structural basis for BBK32-mediated C1r inhibition, we performed crystallography and size-exclusion chromatography-coupled small angle X-ray scattering experiments, which revealed a molecular model of BBK32-C in complex with activated human C1r. Structure-guided site-directed mutagenesis was combined with surface plasmon resonance binding experiments and assays of complement function to validate the predicted molecular interface. Analysis of the structures shows that BBK32 inhibits activated forms of C1r by occluding substrate interaction subsites (i.e., S1 and S1') and reveals a surprising role for C1r B loop-interacting residues for full inhibitory activity of BBK32. The studies reported in this article provide for the first time (to our knowledge) a structural basis for classical pathway-specific inhibition by a human pathogen.
Collapse
Affiliation(s)
- Ryan J Garrigues
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Alexandra D Powell-Pierce
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan/College Station, TX; and
| | - Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Jon T Skare
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan/College Station, TX; and
| | - Brandon L Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC;
| |
Collapse
|
21
|
Kuhn HW, Lasseter AG, Adams PP, Avile CF, Stone BL, Akins DR, Jewett TJ, Jewett MW. BB0562 is a nutritional virulence determinant with lipase activity important for Borrelia burgdorferi infection and survival in fatty acid deficient environments. PLoS Pathog 2021; 17:e1009869. [PMID: 34415955 PMCID: PMC8409650 DOI: 10.1371/journal.ppat.1009869] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 09/01/2021] [Accepted: 08/05/2021] [Indexed: 11/22/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi relies on uptake of essential nutrients from its host environments for survival and infection. Therefore, nutrient acquisition mechanisms constitute key virulence properties of the pathogen, yet these mechanisms remain largely unknown. In vivo expression technology applied to B. burgdorferi (BbIVET) during mammalian infection identified gene bb0562, which encodes a hypothetical protein comprised of a conserved domain of unknown function, DUF3996. DUF3996 is also found across adjacent encoded hypothetical proteins BB0563 and BB0564, suggesting the possibility that the three proteins could be functionally related. Deletion of bb0562, bb0563 and bb0564 individually and together demonstrated that bb0562 alone was important for optimal disseminated infection in immunocompetent and immunocompromised mice by needle inoculation and tick bite transmission. Moreover, bb0562 promoted spirochete survival during the blood dissemination phase of infection. Gene bb0562 was also found to be important for spirochete growth in low serum media and the growth defect of Δbb0562 B. burgdorferi was rescued with the addition of various long chain fatty acids, particularly oleic acid. In mammals, fatty acids are primarily stored in fat droplets in the form of triglycerides. Strikingly, addition of glyceryl trioleate, the triglyceride form of oleic acid, to the low serum media did not rescue the growth defect of the mutant, suggesting bb0562 may be important for the release of fatty acids from triglycerides. Therefore, we searched for and identified two canonical GXSXG lipase motifs within BB0562, despite the lack of homology to known bacterial lipases. Purified BB0562 demonstrated lipolytic activity dependent on the catalytic serine residues within the two motifs. In sum, we have established that bb0562 is a novel nutritional virulence determinant, encoding a lipase that contributes to fatty acid scavenge for spirochete survival in environments deficient in free fatty acids including the mammalian host. Borrelia burgdorferi, the causative agent of Lyme disease, has a small genome and lacks the ability to synthesize essential nutrients on its own as well as many of the virulence properties typical of bacterial pathogens that contribute to disease. The clinical manifestations of Lyme disease predominantly result from inflammation in response to the B. burgdorferi infection. Therefore, nutrient acquisition functions constitute key virulence factors for the pathogen. Fatty acids are critical components of B. burgdorferi membranes and lipoproteins, which the spirochete must scavenge from the host environment. Previously, through a genetic screen for B. burgdorferi genes that are expressed during mammalian infection we identified gene of unknown function, bb0562. Herein, we demonstrate that bb0562 encodes a lipase that plays a role in the release of free fatty acids from triglycerides. Furthermore, bb0562 contributes to B. burgdorferi survival and dissemination in the mammalian host. BB0562 is important for spirochete survival in environments low in free fatty acids thereby adding to B. burgdorferi’s arsenal of nutritional virulence determinants necessary for the pathogen to be maintained in the tick-mouse enzootic cycle and to cause disseminated disease.
Collapse
Affiliation(s)
- Hunter W. Kuhn
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida, United States of America
| | - Amanda G. Lasseter
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida, United States of America
| | - Philip P. Adams
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida, United States of America
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America
- Postdoctoral Research Associate Program, National Institute of General Medical Sciences, National Institute of Health, Bethesda, Maryland, United States of America
| | - Carlos Flores Avile
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida, United States of America
| | - Brandee L. Stone
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Darrin R. Akins
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Travis J. Jewett
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida, United States of America
| | - Mollie W. Jewett
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida, United States of America
- * E-mail:
| |
Collapse
|
22
|
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.
Collapse
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
| |
Collapse
|
23
|
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.
Collapse
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
| |
Collapse
|
24
|
Boyle WK, Richards CL, Dulebohn DP, Zalud AK, Shaw JA, Lovas S, Gherardini FC, Bourret TJ. DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity. PLoS Pathog 2021; 17:e1009072. [PMID: 33600418 PMCID: PMC7924775 DOI: 10.1371/journal.ppat.1009072] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/02/2021] [Accepted: 02/03/2021] [Indexed: 12/14/2022] Open
Abstract
Throughout its enzootic cycle, the Lyme disease spirochete Borreliella (Borrelia) burgdorferi, senses and responds to changes in its environment using a small repertoire of transcription factors that coordinate the expression of genes required for infection of Ixodes ticks and various mammalian hosts. Among these transcription factors, the DnaK suppressor protein (DksA) plays a pivotal role in regulating gene expression in B. burgdorferi during periods of nutrient limitation and is required for mammalian infectivity. In many pathogenic bacteria, the gene regulatory activity of DksA, along with the alarmone guanosine penta- and tetra-phosphate ((p)ppGpp), coordinate the stringent response to various environmental stresses, including nutrient limitation. In this study, we sought to characterize the role of DksA in regulating the transcriptional activity of RNA polymerase and its role in the regulation of RpoS-dependent gene expression required for B. burgdorferi infectivity. Using in vitro transcription assays, we observed recombinant DksA inhibits RpoD-dependent transcription by B. burgdorferi RNA polymerase independent of ppGpp. Additionally, we determined the pH-inducible expression of RpoS-dependent genes relies on DksA, but this relationship is independent of (p)ppGpp produced by Relbbu. Subsequent transcriptomic and western blot assays indicate DksA regulates the expression of BBD18, a protein previously implicated in the post-transcriptional regulation of RpoS. Moreover, we observed DksA was required for infection of mice following intraperitoneal inoculation or for transmission of B. burgdorferi by Ixodes scapularis nymphs. Together, these data suggest DksA plays a central role in coordinating transcriptional responses in B. burgdorferi required for infectivity through DksA’s interactions with RNA polymerase and post-transcriptional control of RpoS. Lyme disease, caused by the spirochete bacteria Borreliella (Borrelia) burgdorferi, is the most common vector-borne illness in North America. The ability of B. burgdorferi to establish infection is predicated by its ability to coordinate the expression of virulence factors in response to diverse environmental stimuli encountered within Ixodes ticks and mammalian hosts. Previous studies have shown an essential role for the alternative sigma factor RpoS in regulating the expression of genes required for the successful transmission of B. burgdorferi by Ixodes ticks and infection of mammalian hosts. The DnaK suppressor protein (DksA) is a global gene regulator in B. burgdorferi that contributes to the expression of RpoS-dependent genes. In this study, using in vitro transcription assays, we determined DksA exerts its gene regulatory function through direct interactions with the B. burgdorferi RNA polymerase and controls the expression of RpoS-dependent genes required for mammalian infection by post-transcriptionally regulating cellular levels of RpoS. Our results demonstrate the utility of in vitro transcription assays to determine how gene regulatory proteins like DksA control gene expression in B. burgdorferi and reveal a novel role for DksA in the infectious cycle of B. burgdorferi.
Collapse
Affiliation(s)
- William K. Boyle
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Crystal L. Richards
- Laboratory of Bacteriology, Gene Regulation Section, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Daniel P. Dulebohn
- Laboratory of Bacteriology, Gene Regulation Section, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Amanda K. Zalud
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Jeff A. Shaw
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Sándor Lovas
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska, United States of America
| | - Frank C. Gherardini
- Laboratory of Bacteriology, Gene Regulation Section, Division of Intramural Research, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Travis J. Bourret
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
- * E-mail:
| |
Collapse
|
25
|
A CRISPR interference platform for selective downregulation of gene expression in Borrelia burgdorferi. Appl Environ Microbiol 2021; 87:AEM.02519-20. [PMID: 33257311 PMCID: PMC7851697 DOI: 10.1128/aem.02519-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The spirochete Borrelia burgdorferi causes Lyme disease, an increasingly prevalent infection. While previous studies have provided important insight into B. burgdorferi biology, many aspects, including basic cellular processes, remain underexplored. To help speed up the discovery process, we adapted a CRISPR interference (CRISPRi) platform for use in B. burgdorferi For efficiency and flexibility of use, we generated various CRISPRi template constructs that produce different basal and induced levels of dcas9 and carry different antibiotic resistance markers. We characterized the effectiveness of our CRISPRi platform by targeting the motility and cell morphogenesis genes flaB, mreB, rodA, and ftsI, whose native expression levels span two orders of magnitude. For all four genes, we obtained gene repression efficiencies of at least 95%. We showed by darkfield microscopy and cryo-electron tomography that flagellin (FlaB) depletion reduced the length and number of periplasmic flagella, which impaired cellular motility and resulted in cell straightening. Depletion of FtsI caused cell filamentation, implicating this protein in cell division in B. burgdorferi Finally, localized cell bulging in MreB- and RodA-depleted cells matched the locations of new peptidoglycan insertion specific to spirochetes of the Borrelia genus. These results therefore implicate MreB and RodA in the particular mode of cell wall elongation of these bacteria. Collectively, our results demonstrate the efficiency and ease of use of our B. burgdorferi CRISPRi platform, which should facilitate future genetic studies of this important pathogen.IMPORTANCE Gene function studies are facilitated by the availability of rapid and easy-to-use genetic tools. Homologous recombination-based methods traditionally used to genetically investigate gene function remain cumbersome to perform in B. burgdorferi, as they often are relatively inefficient. In comparison, our CRISPRi platform offers an easy and fast method to implement as it only requires a single plasmid transformation step and IPTG addition to obtain potent (>95%) downregulation of gene expression. To facilitate studies of various genes in wild-type and genetically modified strains, we provide over 30 CRISPRi plasmids that produce distinct levels of dcas9 expression and carry different antibiotic resistance markers. Our CRISPRi platform represents a useful and efficient complement to traditional genetic and chemical methods to study gene function in B. burgdorferi.
Collapse
|
26
|
Abstract
Genetic studies in Borrelia require special consideration of the highly segmented genome, complex growth requirements and evolutionary distance of spirochetes from other genetically tractable bacteria. Despite these challenges, a robust molecular genetic toolbox has been constructed to investigate the biology and pathogenic potential of these important human pathogens. In this review we summarize the tools and techniques that are currently available for the genetic manipulation of Borrelia, including the relapsing fever spirochetes, viewing them in the context of their utility and shortcomings. Our primary objective is to help researchers discern what is feasible and what is not practical when thinking about potential genetic experiments in Borrelia. We have summarized published methods and highlighted their critical elements, but we are not providing detailed protocols. Although many advances have been made since B. burgdorferi was first transformed over 25 years ago, some standard genetic tools remain elusive for Borrelia. We mention these limitations and why they persist, if known. We hope to encourage investigators to explore what might be possible, in addition to optimizing what currently can be achieved, through genetic manipulation of Borrelia.
Collapse
Affiliation(s)
- Patricia A. Rosa
- Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S 4th St. Hamilton, MT 59840 USA
| | - Mollie W. Jewett
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, 6900 Lake Nona Blvd, Orlando, FL 32827 USA
| |
Collapse
|
27
|
Pal U, Kitsou C, Drecktrah D, Yaş ÖB, Fikrig E. Interactions Between Ticks and Lyme Disease Spirochetes. Curr Issues Mol Biol 2020; 42:113-144. [PMID: 33289683 PMCID: PMC8045411 DOI: 10.21775/cimb.042.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Borrelia burgdorferi sensu lato causes Lyme borreliosis in a variety of animals and humans. These atypical bacterial pathogens are maintained in a complex enzootic life cycle that primarily involves a vertebrate host and Ixodes spp. ticks. In the Northeastern United States, I. scapularis is the main vector, while wild rodents serve as the mammalian reservoir host. As B. burgdorferi is transmitted only by I. scapularis and closely related ticks, the spirochete-tick interactions are thought to be highly specific. Various borrelial and arthropod proteins that directly or indirectly contribute to the natural cycle of B. burgdorferi infection have been identified. Discrete molecular interactions between spirochetes and tick components also have been discovered, which often play critical roles in pathogen persistence and transmission by the arthropod vector. This review will focus on the past discoveries and future challenges that are relevant to our understanding of the molecular interactions between B. burgdorferi and Ixodes ticks. This information will not only impact scientific advancements in the research of tick- transmitted infections but will also contribute to the development of novel preventive measures that interfere with the B. burgdorferi life cycle.
Collapse
Affiliation(s)
- Utpal Pal
- Department of Veterinary Medicine, University of Maryland, 8075 Greenmead Drive, College Park, MD 20742, USA
- Virginia-Maryland College of Veterinary Medicine, 8075 Greenmead Drive, College Park, MD 20742, USA
| | - Chrysoula Kitsou
- Department of Veterinary Medicine, University of Maryland, 8075 Greenmead Drive, College Park, MD 20742, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Özlem Büyüktanir Yaş
- Department of Microbiology and Clinical Microbiology, Faculty of Medicine, Istinye University, Zeytinburnu, İstanbul, 34010, Turkey
| | - Erol Fikrig
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| |
Collapse
|
28
|
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.
Collapse
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
| |
Collapse
|
29
|
The Lon-1 Protease Is Required by Borrelia burgdorferi To Infect the Mammalian Host. Infect Immun 2020; 88:IAI.00951-19. [PMID: 32205400 DOI: 10.1128/iai.00951-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/14/2020] [Indexed: 01/23/2023] Open
Abstract
Borrelia burgdorferi encodes a functional homolog of canonical Lon protease termed Lon-2. In addition, B. burgdorferi encodes a second Lon homolog called Lon-1. Recent studies suggest that Lon-1 may function differently from the prototypical Lon protease. However, the function of Lon-1 in B. burgdorferi biology remains virtually unknown. Particularly, the contribution of Lon-1 to B. burgdorferi fitness and infection remains hitherto unexplored. Herein, we show that Lon-1 plays a critical role for the infection of B. burgdorferi in a mammalian host. We found that lon-1 was highly expressed during animal infection, implying an important function of this protein in bacterial infection. We further generated a lon-1 deletion mutant and an isogenic complemented strain. Relative to that of the wild-type strain, the infectivity of the mutant was severely attenuated in a murine infection model. Our data also showed that the mutant displayed growth defects in regular BSK-II medium. Furthermore, bacterial resistance to osmotic stress was markedly reduced when lon-1 was inactivated. When exposed to tert-butyl hydroperoxide, survival of the lon-1 mutant was impaired. In addition, production of several virulence factors, such as BosR, RpoS, and OspC, was elevated in the mutant. These phenotypes were restored when the lon-1 mutation was complemented. Finally, we created a lon-1(S714A) mutant and found that this mutant failed to infect mice, suggesting that the proteolytic activity of Lon-1 is essential for bacterial infection. Taken together, these results demonstrate that Lon-1 is required by B. burgdorferi to infect animal hosts and to cope with environmental stresses.
Collapse
|
30
|
Establishment of an in vitro RNA polymerase transcription system: a new tool to study transcriptional activation in Borrelia burgdorferi. Sci Rep 2020; 10:8246. [PMID: 32427963 PMCID: PMC7237435 DOI: 10.1038/s41598-020-65104-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/27/2020] [Indexed: 12/04/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi exhibits dramatic changes in gene expression as it transits between its tick vector and vertebrate host. A major hurdle to understanding the mechanisms underlying gene regulation in B. burgdorferi has been the lack of a functional assay to test how gene regulatory proteins and sigma factors interact with RNA polymerase to direct transcription. To gain mechanistic insight into transcriptional control in B. burgdorferi, and address sigma factor function and specificity, we developed an in vitro transcription assay using the B. burgdorferi RNA polymerase holoenzyme. We established reaction conditions for maximal RNA polymerase activity by optimizing pH, temperature, and the requirement for divalent metals. Using this assay system, we analyzed the promoter specificity of the housekeeping sigma factor RpoD to promoters encoding previously identified RpoD consensus sequences in B. burgdorferi. Collectively, this study established an in vitro transcription assay that revealed RpoD-dependent promoter selectivity by RNA polymerase and the requirement of specific metal cofactors for maximal RNA polymerase activity. The establishment of this functional assay will facilitate molecular and biochemical studies on how gene regulatory proteins and sigma factors exert control of gene expression in B. burgdorferi required for the completion of its enzootic cycle.
Collapse
|
31
|
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.
Collapse
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
| |
Collapse
|
32
|
Mason C, Thompson C, Ouyang Z. DksA plays an essential role in regulating the virulence of Borrelia burgdorferi. Mol Microbiol 2020; 114:172-183. [PMID: 32227372 DOI: 10.1111/mmi.14504] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/13/2020] [Accepted: 03/20/2020] [Indexed: 12/16/2022]
Abstract
The RNA polymerase-binding protein DksA, together with the alarmone nucleotides (p)ppGpp, mediates the stringent response to nutrient starvation in Borrelia burgdorferi. To date, the contribution of DksA to B. burgdorferi infection remains unknown. We report here that DksA is essential for B. burgdorferi to infect a mammalian host. dksA expression was highly induced during infection. Moreover, a dksA-deficient mutant was incapable of infecting mice. The mutant displayed growth defects when cultured in vitro and resistance to osmotic pressure was markedly reduced. These phenotypes were fully restored to those of the wild type when dksA mutation was complemented. We further showed that DksA controlled the expression of virulence-associated lipoprotein OspC, likely via the central alternative sigma factor RpoS. Synthesis of RpoS was abolished in the dksA mutant, but rpoS transcription remained unaffected. Additionally, we found that the expression of clpX, clpA, clpP, and clpP2 was significantly increased in the mutant, suggesting that DksA may post-transcriptionally regulate rpoS expression via its effect on ClpXP and/or ClpAP proteases. These combined data demonstrate that DksA regulates B. burgdorferi virulence at least partially through its influence on RpoS and OspC. This study thus elucidates that, in addition to function as a stringent response regulator, DksA promotes the transcription and/or translation of genes contributing to B. burgdorferi infectivity.
Collapse
Affiliation(s)
- Charlotte Mason
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| |
Collapse
|
33
|
Zhang K, He J, Cantalano C, Guo Y, Liu J, Li C. FlhF regulates the number and configuration of periplasmic flagella in Borrelia burgdorferi. Mol Microbiol 2020; 113:1122-1139. [PMID: 32039533 DOI: 10.1111/mmi.14482] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/17/2022]
Abstract
The Lyme disease bacterium Borrelia burgdorferi has 7-11 periplasmic flagella (PF) that arise from the cell poles and extend toward the midcell as a flat-ribbon, which is distinct from other bacteria. FlhF, a signal recognition particle (SRP)-like GTPase, has been found to regulate the flagellar number and polarity; however, its role in B. burgdorferi remains unknown. B. burgdorferi has an FlhF homolog (BB0270). Structural and biochemical analyses show that BB0270 has a similar structure and enzymatic activity as its counterparts from other bacteria. Genetics and cryo-electron tomography studies reveal that deletion of BB0270 leads to mutant cells that have less PF (4 ± 2 PF per cell tip) and fail to form a flat-ribbon, indicative of a role of BB0270 in the control of PF number and configuration. Mechanistically, we demonstrate that BB0270 localizes at the cell poles and controls the number and position of PF via regulating the flagellar protein stability and the polar localization of the MS-ring protein FliF. Our study not only provides the detailed characterizations of BB0270 and its profound impacts on flagellar assembly, morphology and motility in B. burgdorferi, but also unveils mechanistic insights into how spirochetes control their unique flagellar patterns.
Collapse
Affiliation(s)
- Kai Zhang
- Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA, USA
| | - Jun He
- Department of Microbial Pathogenesis, Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Claudio Cantalano
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA.,Institute for Structural Biology, Drug Discovery and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Youzhong Guo
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA.,Institute for Structural Biology, Drug Discovery and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Chunhao Li
- Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| |
Collapse
|
34
|
Drecktrah D, Hall LS, Brinkworth AJ, Comstock JR, Wassarman KM, Samuels DS. Characterization of 6S RNA in the Lyme disease spirochete. Mol Microbiol 2020; 113:399-417. [PMID: 31742773 PMCID: PMC7047579 DOI: 10.1111/mmi.14427] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 11/05/2019] [Accepted: 11/16/2019] [Indexed: 12/31/2022]
Abstract
6S RNA binds to RNA polymerase and regulates gene expression, contributing to bacterial adaptation to environmental stresses. In this study, we examined the role of 6S RNA in murine infectivity and tick persistence of the Lyme disease spirochete Borrelia (Borreliella) burgdorferi. B. burgdorferi 6S RNA (Bb6S RNA) binds to RNA polymerase, is expressed independent of growth phase or nutrient stress in culture, and is processed by RNase Y. We found that rny (bb0504), the gene encoding RNase Y, is essential for B. burgdorferi growth, while ssrS, the gene encoding 6S RNA, is not essential, indicating a broader role for RNase Y activity in the spirochete. Bb6S RNA regulates expression of the ospC and dbpA genes encoding outer surface protein C and decorin binding protein A, respectively, which are lipoproteins important for host infection. The highest levels of Bb6S RNA are found when the spirochete resides in unfed nymphs. ssrS mutants lacking Bb6S RNA were compromised for infectivity by needle inoculation, but injected mice seroconverted, indicating an ability to activate the adaptive immune response. ssrS mutants were successfully acquired by larval ticks and persisted through fed nymphs. Bb6S RNA is one of the first regulatory RNAs identified in B. burgdorferi that controls the expression of lipoproteins involved in host infectivity.
Collapse
Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | | | | | - Karen M. Wassarman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - D. Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA
| |
Collapse
|
35
|
Mason C, Thompson C, Ouyang Z. The Lon-2 protease of Borrelia burgdorferi is critical for infection in the mammalian host. Mol Microbiol 2020; 113:938-950. [PMID: 31955462 DOI: 10.1111/mmi.14460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/10/2020] [Accepted: 01/13/2020] [Indexed: 01/08/2023]
Abstract
Borrelia burgdorferi encodes a functional homolog of canonical Lon protease termed Lon-2. To date, the contribution of Lon-2 to B. burgdorferi fitness and infection remains unexplored. Herein, we showed that expression of lon-2 was highly induced during animal infection, suggesting that Lon-2 is important for B. burgdorferi infection. We further generated a lon-2 deletion mutant. Compared with that of wild-type (WT) strain, the infectivity of the mutant was severely attenuated in a murine infection model. Although no growth defect was observed for the mutant in normal BSK-II medium, resistance of the lon-2 mutant to osmotic stress was markedly reduced. In addition, when exposed to tert-Butyl hydroperoxide, survival of the lon-2 mutant was impaired. In addition, we found that the protein levels of RpoS and RpoS-dependent OspC were decreased in the mutant. All these phenotypes were restored to WT or near-WT levels when lon-2 mutation was complemented in cis. Taken together, these results demonstrate that Lon-2 is critical for B. burgdorferi to establish infection and to cope with environmental stresses. This study provides a foundation for further uncovering the direct link between the dual roles of Lon-2 in protein quality control and bacterial pathogenesis.
Collapse
Affiliation(s)
- Charlotte Mason
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL, USA
| |
Collapse
|
36
|
Xu H, He J, Liu J, Motaleb MA. BB0326 is responsible for the formation of periplasmic flagellar collar and assembly of the stator complex in Borrelia burgdorferi. Mol Microbiol 2019; 113:418-429. [PMID: 31743518 DOI: 10.1111/mmi.14428] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 11/15/2019] [Accepted: 11/16/2019] [Indexed: 12/19/2022]
Abstract
Borrelia burgdorferi is a highly motile spirochete due to its periplasmic flagella. Unlike flagella of other bacteria, spirochetes' periplasmic flagella possess a complex structure called the collar, about which little is known in terms of function and composition. Using various approaches, we have identified a novel protein, BB0326, as a key component of the collar. We show that a peripheral portion of the collar is diminished in the Δbb0326 mutant and restored in the complemented bb0326+ cells, leading us to rename BB0326 as periplasmic flagellar collar protein A or FlcA. The ΔflcA mutant cells produced fewer, abnormally tilted and shorter flagella, as well as diminished stators, suggesting that FlcA is crucial for flagellar and stator assemblies. We provide further evidence that FlcA interacts with the stator and that this collar-stator interaction is essential for the high torque needed to power the spirochete's periplasmic flagellar motors. These observations suggest that the collar provides various important functions to the spirochete's periplasmic flagellar assembly and rotation.
Collapse
Affiliation(s)
- Hui Xu
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Jun He
- Department of Microbial Pathogenesis, Microbial Sciences Institute, Yale School of Medicine, New Haven, CT, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Microbial Sciences Institute, Yale School of Medicine, New Haven, CT, USA
| | - Md A Motaleb
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| |
Collapse
|
37
|
Caimano MJ, Groshong AM, Belperron A, Mao J, Hawley KL, Luthra A, Graham DE, Earnhart CG, Marconi RT, Bockenstedt LK, Blevins JS, Radolf JD. The RpoS Gatekeeper in Borrelia burgdorferi: An Invariant Regulatory Scheme That Promotes Spirochete Persistence in Reservoir Hosts and Niche Diversity. Front Microbiol 2019; 10:1923. [PMID: 31507550 PMCID: PMC6719511 DOI: 10.3389/fmicb.2019.01923] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/05/2019] [Indexed: 11/28/2022] Open
Abstract
Maintenance of Borrelia burgdorferi within its enzootic cycle requires a complex regulatory pathway involving the alternative σ factors RpoN and RpoS and two ancillary trans-acting factors, BosR and Rrp2. Activation of this pathway occurs within ticks during the nymphal blood meal when RpoS, the effector σ factor, transcribes genes required for tick transmission and mammalian infection. RpoS also exerts a 'gatekeeper' function by repressing σ70-dependent tick phase genes (e.g., ospA, lp6.6). Herein, we undertook a broad examination of RpoS functionality throughout the enzootic cycle, beginning with modeling to confirm that this alternative σ factor is a 'genuine' RpoS homolog. Using a novel dual color reporter system, we established at the single spirochete level that ospA is expressed in nymphal midguts throughout transmission and is not downregulated until spirochetes have been transmitted to a naïve host. Although it is well established that rpoS/RpoS is expressed throughout infection, its requirement for persistent infection has not been demonstrated. Plasmid retention studies using a trans-complemented ΔrpoS mutant demonstrated that (i) RpoS is required for maximal fitness throughout the mammalian phase and (ii) RpoS represses tick phase genes until spirochetes are acquired by a naïve vector. By transposon mutant screening, we established that bba34/oppA5, the only OppA oligopeptide-binding protein controlled by RpoS, is a bona fide persistence gene. Lastly, comparison of the strain 297 and B31 RpoS DMC regulons identified two cohorts of RpoS-regulated genes. The first consists of highly conserved syntenic genes that are similarly regulated by RpoS in both strains and likely required for maintenance of B. burgdorferi sensu stricto strains in the wild. The second includes RpoS-regulated plasmid-encoded variable surface lipoproteins ospC, dbpA and members of the ospE/ospF/elp, mlp, revA, and Pfam54 paralogous gene families, all of which have evolved via inter- and intra-strain recombination. Thus, while the RpoN/RpoS pathway regulates a 'core' group of orthologous genes, diversity within RpoS regulons of different strains could be an important determinant of reservoir host range as well as spirochete virulence.
Collapse
Affiliation(s)
- Melissa J. Caimano
- Department of Medicine, UConn Health, Farmington, CT, United States,Department of Pediatrics, UConn Health, Farmington, CT, United States,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States,*Correspondence: Melissa J. Caimano,
| | | | - Alexia Belperron
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jialing Mao
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Kelly L. Hawley
- Department of Pediatrics, UConn Health, Farmington, CT, United States,Division of Infectious Diseases and Immunology, Connecticut Children’s Medical Center, Hartford, CT, United States
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, CT, United States
| | - Danielle E. Graham
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Christopher G. Earnhart
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Richard T. Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Linda K. Bockenstedt
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jon S. Blevins
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, CT, United States,Department of Pediatrics, UConn Health, Farmington, CT, United States,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States,Department of Genetics and Genome Science, UConn Health, Farmington, CT, United States,Department of Immunology, UConn Health, Farmington, CT, United States
| |
Collapse
|
38
|
Phelan JP, Kern A, Ramsey ME, Lundt ME, Sharma B, Lin T, Gao L, Norris SJ, Hyde JA, Skare JT, Hu LT. Genome-wide screen identifies novel genes required for Borrelia burgdorferi survival in its Ixodes tick vector. PLoS Pathog 2019; 15:e1007644. [PMID: 31086414 PMCID: PMC6516651 DOI: 10.1371/journal.ppat.1007644] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/15/2019] [Indexed: 12/25/2022] Open
Abstract
Borrelia burgdorferi, the causative agent of Lyme disease in humans, is maintained in a complex biphasic life cycle, which alternates between tick and vertebrate hosts. To successfully survive and complete its enzootic cycle, B. burgdorferi adapts to diverse hosts by regulating genes required for survival in specific environments. Here we describe the first ever use of transposon insertion sequencing (Tn-seq) to identify genes required for B. burgdorferi survival in its tick host. We found that insertions into 46 genes resulted in a complete loss of recovery of mutants from larval Ixodes ticks. Insertions in an additional 56 genes resulted in a >90% decrease in fitness. The screen identified both previously known and new genes important for larval tick survival. Almost half of the genes required for survival in the tick encode proteins of unknown function, while a significant portion (over 20%) encode membrane-associated proteins or lipoproteins. We validated the results of the screen for five Tn mutants by performing individual competition assays using mutant and complemented strains. To better understand the role of one of these genes in tick survival, we conducted mechanistic studies of bb0017, a gene previously shown to be required for resistance against oxidative stress. In this study we show that BB0017 affects the regulation of key borrelial virulence determinants. The application of Tn-seq to in vivo screening of B. burgdorferi in its natural vector is a powerful tool that can be used to address many different aspects of the host pathogen interaction. Borrelia burgdorferi, the causative agent of Lyme disease, must adjust to environmental changes as it moves between its tick and vertebrate hosts. We performed a screen of a B. burgdorferi transposon library using massively parallel sequencing (Tn-seq) to identify fitness defects involved in survival in its tick host. This screen accurately identified genes known to cause decreased fitness for tick survival and identified new genes involved in B. burgdorferi survival in ticks. All of the genes tested individually confirmed the Tn-seq results. One of the genes identified encodes a protein whose function was previously unknown that appears to be involved in regulating expression of proteins known to be involved in environmental adaptation. Tn-seq is a powerful tool for understanding vector-pathogen interactions and may reveal new opportunities for interrupting the infectious cycle of vector-borne diseases.
Collapse
Affiliation(s)
- James P. Phelan
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
- * E-mail: (JPP); (STH)
| | - Aurelie Kern
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
| | - Meghan E. Ramsey
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
| | - Maureen E. Lundt
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
| | - Bijaya Sharma
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
| | - Tao Lin
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lihui Gao
- MD Anderson Cancer Center Thoracic & Cardiovascular Surgery, Houston, Texas, United States of America
| | - Steven J. Norris
- Department of Pathology and Laboratory Medicine, McGovern Medical School at UT Health, Houston, Texas, 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
| | - Jon T. Skare
- Department of Microbial Pathogenesis and Immunology, Texas A & M University Health Science Center, Bryan, Texas, United States of America
| | - Linden T. Hu
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
- * E-mail: (JPP); (STH)
| |
Collapse
|
39
|
Zhang K, Qin Z, Chang Y, Liu J, Malkowski MG, Shipa S, Li L, Qiu W, Zhang JR, Li C. Analysis of a flagellar filament cap mutant reveals that HtrA serine protease degrades unfolded flagellin protein in the periplasm of Borrelia burgdorferi. Mol Microbiol 2019; 111:1652-1670. [PMID: 30883947 DOI: 10.1111/mmi.14243] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2019] [Indexed: 12/16/2022]
Abstract
Unlike external flagellated bacteria, spirochetes have periplasmic flagella (PF). Very little is known about how PF are assembled within the periplasm of spirochaetal cells. Herein, we report that FliD (BB0149), a flagellar cap protein (also named hook-associated protein 2), controls flagellin stability and flagellar filament assembly in the Lyme disease spirochete Borrelia burgdorferi. Deletion of fliD leads to non-motile mutant cells that are unable to assemble flagellar filaments and pentagon-shaped caps (10 nm in diameter, 12 nm in length). Interestingly, FlaB, a major flagellin protein of B. burgdorferi, is degraded in the fliD mutant but not in other flagella-deficient mutants (i.e., in the hook, rod, or MS-ring). Biochemical and genetic studies reveal that HtrA, a serine protease of B. burgdorferi, controls FlaB turnover. Specifically, HtrA degrades unfolded but not polymerized FlaB, and deletion of htrA increases the level of FlaB in the fliD mutant. Collectively, we propose that the flagellar cap protein FliD promotes flagellin polymerization and filament growth in the periplasm. Deletion of fliD abolishes this process, which leads to leakage of unfolded FlaB proteins into the periplasm where they are degraded by HtrA, a protease that prevents accumulation of toxic products in the periplasm.
Collapse
Affiliation(s)
- Kai Zhang
- Department of Oral and Craniofacial Molecular Biology, Philips Research Institute, Virginia Commonwealth University, Richmond, VI, 23298, USA
| | - Zhuan Qin
- Department of Microbial Pathogenesis & Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, 06516, USA
| | - Yunjie Chang
- Department of Microbial Pathogenesis & Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, 06516, USA
| | - Jun Liu
- Department of Microbial Pathogenesis & Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, 06516, USA
| | - Michael G Malkowski
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, Buffalo, NY, 14203, USA
| | - Saimtun Shipa
- Department of Biological Sciences, City University of New York, New York, NY, 10021, USA
| | - Li Li
- Department of Biological Sciences, City University of New York, New York, NY, 10021, USA
| | - Weigang Qiu
- Department of Biological Sciences, City University of New York, New York, NY, 10021, USA
| | - Jing-Ren Zhang
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Chunhao Li
- Department of Oral and Craniofacial Molecular Biology, Philips Research Institute, Virginia Commonwealth University, Richmond, VI, 23298, USA
| |
Collapse
|
40
|
Mason C, Liu X, Prabhudeva S, Ouyang Z. The CXXC Motifs Are Essential for the Function of BosR in Borrelia burgdorferi. Front Cell Infect Microbiol 2019; 9:109. [PMID: 31041197 PMCID: PMC6476982 DOI: 10.3389/fcimb.2019.00109] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/28/2019] [Indexed: 01/07/2023] Open
Abstract
BosR, a Fur family member, is essential for the pathogenesis of the Lyme disease pathogen, Borrelia burgdorferi. Unlike typical Fur proteins in which DNA binding represses gene expression, binding of BosR to the rpoS promoter directly activates rpoS transcription in B. burgdorferi. However, virtually nothing is known concerning potential structural features and amino acid residues of BosR that are important for protein function and virulence regulation in B. burgdorferi. Particularly, it remains unknown what structural motifs or residues of BosR coordinate Zn, although previous analyses have indicated that the function of BosR may depend on Zn. To address these information gaps, we herein introduced mutations into four conserved cysteine residues in two putative CXXC motifs of BosR. Our data showed that the ability of BosR to bind Zn was dramatically reduced when the CXXC motifs were mutated. Moreover, we found that the two CXXC motifs contributed to the ability of BosR to form dimers. By using a trans-complementation genetic approach, we additionally demonstrated that both CXXC motifs of BosR were essential for in vivo gene expression regulation. Mutation of any of the four cysteines abolished the transcriptional activation of rpoS. In contrast to wild type BosR, each mutant protein was incapable of binding the rpoS promoter in electrophoretic mobility shift assays. The combined data strongly support that the two CXXC motifs and four cysteines constitute the structural site essential for Zn-coordination, protein dimerization, and the unique regulatory activity of BosR.
Collapse
Affiliation(s)
- Charlotte Mason
- Department of Molecular Medicine, University of South Florida, Tampa, FL, United States
| | - Xiaoyan Liu
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Spoorthy Prabhudeva
- Department of Molecular Medicine, University of South Florida, Tampa, FL, United States
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, FL, United States
| |
Collapse
|
41
|
Structural determination of the complement inhibitory domain of Borrelia burgdorferi BBK32 provides insight into classical pathway complement evasion by Lyme disease spirochetes. PLoS Pathog 2019; 15:e1007659. [PMID: 30897158 PMCID: PMC6445466 DOI: 10.1371/journal.ppat.1007659] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 04/02/2019] [Accepted: 02/26/2019] [Indexed: 01/07/2023] Open
Abstract
The carboxy-terminal domain of the BBK32 protein from Borrelia burgdorferi sensu stricto, termed BBK32-C, binds and inhibits the initiating serine protease of the human classical complement pathway, C1r. In this study we investigated the function of BBK32 orthologues of the Lyme-associated Borrelia burgdorferi sensu lato complex, designated BAD16 from B. afzelii strain PGau and BGD19 from B. garinii strain IP90. Our data show that B. afzelii BAD16-C exhibits BBK32-C-like activities in all assays tested, including high-affinity binding to purified C1r protease and C1 complex, and potent inhibition of the classical complement pathway. Recombinant B. garinii BGD19-C also bound C1 and C1r with high-affinity yet exhibited significantly reduced in vitro complement inhibitory activities relative to BBK32-C or BAD16-C. Interestingly, natively produced BGD19 weakly recognized C1r relative to BBK32 and BAD16 and, unlike these proteins, BGD19 did not confer significant protection from serum killing. Site-directed mutagenesis was performed to convert BBK32-C to resemble BGD19-C at three residue positions that are identical between BBK32 and BAD16 but different in BGD19. The resulting chimeric protein was designated BXK32-C and this BBK32-C variant mimicked the properties observed for BGD19-C. To query the disparate complement inhibitory activities of BBK32 orthologues, the crystal structure of BBK32-C was solved to 1.7Å limiting resolution. BBK32-C adopts an anti-parallel four-helix bundle fold with a fifth alpha-helix protruding from the helical core. The structure revealed that the three residues targeted in the BXK32-C chimera are surface-exposed, further supporting their potential relevance in C1r binding and inhibition. Additional binding assays showed that BBK32-C only recognized C1r fragments containing the serine protease domain. The structure-function studies reported here improve our understanding of how BBK32 recognizes and inhibits C1r and provide new insight into complement evasion mechanisms of Lyme-associated spirochetes of the B. burgdorferi sensu lato complex.
Collapse
|
42
|
DksA Controls the Response of the Lyme Disease Spirochete Borrelia burgdorferi to Starvation. J Bacteriol 2019; 201:JB.00582-18. [PMID: 30478087 PMCID: PMC6351744 DOI: 10.1128/jb.00582-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/20/2018] [Indexed: 12/17/2022] Open
Abstract
The pathogenic spirochete Borrelia burgdorferi senses and responds to changes in the environment, including changes in nutrient availability, throughout its enzootic cycle in Ixodes ticks and vertebrate hosts. This study examined the role of DnaK suppressor protein (DksA) in the transcriptional response of B. burgdorferi to starvation. Wild-type and dksA mutant B. burgdorferi strains were subjected to starvation by shifting cultures grown in rich complete medium, Barbour-Stoenner-Kelly II (BSK II) medium, to a defined mammalian tissue culture medium, RPMI 1640, for 6 h under microaerobic conditions (5% CO2, 3% O2). Microarray analyses of wild-type B. burgdorferi revealed that genes encoding flagellar components, ribosomal proteins, and DNA replication machinery were downregulated in response to starvation. DksA mediated transcriptomic responses to starvation in B. burgdorferi, as the dksA-deficient strain differentially expressed only 47 genes in response to starvation compared to the 500 genes differentially expressed in wild-type strains. Consistent with a role for DksA in the starvation response of B. burgdorferi, fewer CFU of dksA mutants were observed after prolonged starvation in RPMI 1640 medium than CFU of wild-type B. burgdorferi spirochetes. Transcriptomic analyses revealed a partial overlap between the DksA regulon and the regulon of RelBbu, the guanosine tetraphosphate and guanosine pentaphosphate [(p)ppGpp] synthetase that controls the stringent response; the DksA regulon also included many plasmid-borne genes. Additionally, the dksA mutant exhibited constitutively elevated (p)ppGpp levels compared to those of the wild-type strain, implying a regulatory relationship between DksA and (p)ppGpp. Together, these data indicate that DksA, along with (p)ppGpp, directs the stringent response to effect B. burgdorferi adaptation to its environment.IMPORTANCE The Lyme disease bacterium Borrelia burgdorferi survives diverse environmental challenges as it cycles between its tick vectors and various vertebrate hosts. B. burgdorferi must withstand prolonged periods of starvation while it resides in unfed Ixodes ticks. In this study, the regulatory protein DksA is shown to play a pivotal role controlling the transcriptional responses of B. burgdorferi to starvation. The results suggest that DksA gene regulatory activity impacts B. burgdorferi metabolism, virulence gene expression, and the ability of this bacterium to complete its natural life cycle.
Collapse
|
43
|
Takacs CN, Kloos ZA, Scott M, Rosa PA, Jacobs-Wagner C. Fluorescent Proteins, Promoters, and Selectable Markers for Applications in the Lyme Disease Spirochete Borrelia burgdorferi. Appl Environ Microbiol 2018; 84:e01824-18. [PMID: 30315081 PMCID: PMC6275353 DOI: 10.1128/aem.01824-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/08/2018] [Indexed: 11/30/2022] Open
Abstract
Lyme disease is the most widely reported vector-borne disease in the United States. Its incidence is rapidly increasing, and disease symptoms can be debilitating. The need to understand the biology of the disease agent, the spirochete Borrelia burgdorferi, is thus evermore pressing. Despite important advances in B. burgdorferi genetics, the array of molecular tools available for use in this organism remains limited, especially for cell biological studies. Here, we adapt a palette of bright and mostly monomeric fluorescent proteins for versatile use and multicolor imaging in B. burgdorferi We also characterize two novel antibiotic selection markers and establish the feasibility of their use in conjunction with extant markers. Last, we describe a set of promoters of low and intermediate strengths that allow fine-tuning of gene expression levels. These molecular tools complement and expand current experimental capabilities in B. burgdorferi, which will facilitate future investigation of this important human pathogen. To showcase the usefulness of these reagents, we used them to investigate the subcellular localization of BB0323, a B. burgdorferi lipoprotein essential for survival in the host and vector environments. We show that BB0323 accumulates at the cell poles and future division sites of B. burgdorferi cells, highlighting the complex subcellular organization of this spirochete.IMPORTANCE Genetic manipulation of the Lyme disease spirochete B. burgdorferi remains cumbersome, despite significant progress in the field. The scarcity of molecular reagents available for use in this pathogen has slowed research efforts to study its unusual biology. Of interest, B. burgdorferi displays complex cellular organization features that have yet to be understood. These include an unusual morphology and a highly fragmented genome, both of which are likely to play important roles in the bacterium's transmission, infectivity, and persistence. Here, we complement and expand the array of molecular tools available for use in B. burgdorferi by generating and characterizing multiple fluorescent proteins, antibiotic selection markers, and promoters of varied strengths. These tools will facilitate investigations in this important human pathogen, as exemplified by the polar and midcell localization of the cell envelope regulator BB0323, which we uncovered using these reagents.
Collapse
Affiliation(s)
- Constantin N Takacs
- Microbial Sciences Institute, Yale West Campus, West Haven, Connecticut, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
- Howard Hughes Medical Institute, Yale West Campus, West Haven, Connecticut, USA
| | - Zachary A Kloos
- Microbial Sciences Institute, Yale West Campus, West Haven, Connecticut, USA
- Microbiology Program, Yale University, New Haven, Connecticut, USA
| | - Molly Scott
- Microbial Sciences Institute, Yale West Campus, West Haven, Connecticut, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
- Howard Hughes Medical Institute, Yale West Campus, West Haven, Connecticut, USA
| | - Patricia A Rosa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Christine Jacobs-Wagner
- Microbial Sciences Institute, Yale West Campus, West Haven, Connecticut, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
- Howard Hughes Medical Institute, Yale West Campus, West Haven, Connecticut, USA
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| |
Collapse
|
44
|
Drecktrah D, Hall LS, Rescheneder P, Lybecker M, Samuels DS. The Stringent Response-Regulated sRNA Transcriptome of Borrelia burgdorferi. Front Cell Infect Microbiol 2018; 8:231. [PMID: 30027068 PMCID: PMC6041397 DOI: 10.3389/fcimb.2018.00231] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/19/2018] [Indexed: 12/12/2022] Open
Abstract
The Lyme disease spirochete Borrelia (Borreliella) burgdorferi must tolerate nutrient stress to persist in the tick phase of its enzootic life cycle. We previously found that the stringent response mediated by RelBbu globally regulates gene expression to facilitate persistence in the tick vector. Here, we show that RelBbu regulates the expression of a swath of small RNAs (sRNA), affecting 36% of previously identified sRNAs in B. burgdorferi. This is the first sRNA regulatory mechanism identified in any spirochete. Threefold more sRNAs were RelBbu-upregulated than downregulated during nutrient stress and included antisense, intergenic and 5′ untranslated region sRNAs. RelBbu-regulated sRNAs associated with genes known to be important for host infection (bosR and dhhp) as well as persistence in the tick (glpF and hk1) were identified, suggesting potential mechanisms for post-transcriptional regulation of gene expression.
Collapse
Affiliation(s)
- Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Laura S Hall
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Philipp Rescheneder
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories, Medical University of Vienna, Vienna, Austria
| | - Meghan Lybecker
- Department of Biology, University of Colorado, Colorado Springs, CO, United States
| | - D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT, United States.,Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, United States
| |
Collapse
|
45
|
Anacker ML, Drecktrah D, LeCoultre RD, Lybecker M, Samuels DS. RNase III Processing of rRNA in the Lyme Disease Spirochete Borrelia burgdorferi. J Bacteriol 2018; 200:e00035-18. [PMID: 29632096 PMCID: PMC5996687 DOI: 10.1128/jb.00035-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/04/2018] [Indexed: 02/08/2023] Open
Abstract
The rRNA genes of Borrelia (Borreliella) burgdorferi are unusually organized; the spirochete has a single 16S rRNA gene that is more than 3 kb from a tandem pair of 23S-5S rRNA operons. We generated an rnc null mutant in B. burgdorferi that exhibits a pleiotropic phenotype, including decreased growth rate and increased cell length. Here, we demonstrate that endoribonuclease III (RNase III) is, as expected, involved in processing the 23S rRNA in B. burgdorferi The 5' and 3' ends of the three rRNAs were determined in the wild type and rncBb mutants; the results suggest that RNase III in B. burgdorferi is required for the full maturation of the 23S rRNA but not for the 5S rRNA nor, curiously, for the 16S rRNA.IMPORTANCE Lyme disease, the most common tick-borne zoonosis in the Northern Hemisphere, is caused by the bacterium Borrelia (Borreliella) burgdorferi, a member of the deeply branching spirochete phylum. B. burgdorferi carries a limited suite of ribonucleases, enzymes that cleave RNA during processing and degradation. Several ribonucleases, including RNase III, are involved in the production of ribosomes, which catalyze translation and are a major target of antibiotics. This is the first study to dissect the role of an RNase in any spirochete. We demonstrate that an RNase III mutant is viable but has altered processing of rRNA.
Collapse
MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Borrelia burgdorferi/enzymology
- Borrelia burgdorferi/genetics
- Borrelia burgdorferi/metabolism
- Humans
- Lyme Disease/microbiology
- Operon
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
- RNA, Ribosomal, 5S/genetics
- RNA, Ribosomal, 5S/metabolism
- Ribonuclease III/genetics
- Ribonuclease III/metabolism
Collapse
Affiliation(s)
- Melissa L Anacker
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Richard D LeCoultre
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Meghan Lybecker
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Department of Biology, University of Colorado, Colorado Springs, Colorado, USA
| | - D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, USA
| |
Collapse
|