1
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Bourgeois JS, Hu LT. Hitchhiker's Guide to Borrelia burgdorferi. J Bacteriol 2024:e0011624. [PMID: 39140751 DOI: 10.1128/jb.00116-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [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.
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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
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2
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Thompson C, Waldron C, George S, Ouyang Z. Assessment of the hypothetical protein BB0616 in the murine infection of Borrelia burgdorferi. Infect Immun 2024; 92:e0009024. [PMID: 38700336 PMCID: PMC11237664 DOI: 10.1128/iai.00090-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 04/08/2024] [Indexed: 05/05/2024] Open
Abstract
bb0616 of Borrelia burgdorferi, the Lyme disease pathogen, encodes a hypothetical protein of unknown function. In this study, we showed that BB0616 was not surface-exposed or associated with the membrane through localization analyses using proteinase K digestion and cell partitioning assays. The expression of bb0616 was influenced by a reduced pH but not by growth phases, elevated temperatures, or carbon sources during in vitro cultivation. A transcriptional start site for bb0616 was identified by using 5' rapid amplification of cDNA ends, which led to the identification of a functional promoter in the 5' regulatory region upstream of bb0616. By analyzing a bb0616-deficient mutant and its isogenic complemented counterparts, we found that the infectivity potential of the mutant was significantly attenuated. The inactivation of bb0616 displayed no effect on borrelial growth in the medium or resistance to oxidative stress, but the mutant was significantly more susceptible to osmotic stress. In addition, the production of global virulence regulators such as BosR and RpoS as well as virulence-associated outer surface lipoproteins OspC and DbpA was reduced in the mutant. These phenotypes were fully restored when gene mutation was complemented with a wild-type copy of bb0616. Based on these findings, we concluded that the hypothetical protein BB0616 is required for the optimal infectivity of B. burgdorferi, potentially by impacting B. burgdorferi virulence gene expression as well as survival of the spirochete under stressful conditions.
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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
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3
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Raghunandanan S, Zhang K, Zhang Y, Sze CW, Priya R, Luo Y, Lynch MJ, Crane BR, Li C, Yang XF. MCP5, a methyl-accepting chemotaxis protein regulated by both the Hk1-Rrp1 and Rrp2-RpoN-RpoS pathways, is required for the immune evasion of Borrelia burgdorferi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.598185. [PMID: 38915556 PMCID: PMC11195095 DOI: 10.1101/2024.06.10.598185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Borrelia (or Borreliella) burgdorferi, the causative agent of Lyme disease, is a motile and invasive zoonotic pathogen, adept at navigating between its arthropod vector and mammalian host. While motility and chemotaxis are well established as essential for its enzootic cycle, the function of methyl-accepting chemotaxis proteins (MCPs) in the infectious cycle of B. burgdorferi remains unclear. In this study, we demonstrate that MCP5, one of the most abundant MCPs in B. burgdorferi, is differentially expressed in response to environmental signals as well as at different stages of the pathogen's enzootic cycle. Specifically, the expression of mcp5 is regulated by the Hk1-Rrp1 and Rrp2-RpoN-RpoS pathways, which are critical for the spirochete's colonization of the tick vector and mammalian host, respectively. Infection experiments with an mcp5 mutant revealed that spirochetes lacking MCP5 could not establish infections in either C3H/HeN mice or Severe Combined Immunodeficiency (SCID) mice, which are defective in adaptive immunity, indicating the essential role of MCP5 in mammalian infection. However, the mcp5 mutant could establish infection and disseminate in NOD SCID Gamma (NSG) mice, which are deficient in both adaptive and most innate immune responses, suggesting a crucial role of MCP5 in evading host innate immunity. In the tick vector, the mcp5 mutants survived feeding but failed to transmit to mice, highlighting the importance of MCP5 in transmission. Our findings reveal that MCP5, regulated by the Rrp1 and Rrp2 pathways, is critical for the establishment of infection in mammalian hosts by evading host innate immunity and is important for the transmission of spirochetes from ticks to mammalian hosts, underscoring its potential as a target for intervention strategies.
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Affiliation(s)
- Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Kai Zhang
- Department of Oral Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - Yan Zhang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China, 325035
| | - Ching Wooen Sze
- Department of Oral Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - Raj Priya
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Yongliang Luo
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China, 325035
| | - Michael J Lynch
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Chunhao Li
- Department of Oral Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
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4
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Zhang JJ, Raghunandanan S, Wang Q, Priya R, Alanazi F, Lou Y, Yang XF. BadR directly represses the expression of the glycerol utilization operon in the Lyme disease pathogen. J Bacteriol 2024; 206:e0034023. [PMID: 38214528 PMCID: PMC10882987 DOI: 10.1128/jb.00340-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 12/14/2023] [Indexed: 01/13/2024] Open
Abstract
Glycerol utilization as a carbohydrate source by Borreliella burgdorferi, the Lyme disease spirochete, is critical for its successful colonization and persistence in the tick vector. The expression of the glpFKD (glp) operon, which encodes proteins for glycerol uptake/utilization, must be tightly regulated during the enzootic cycle of B. burgdorferi. Previous studies have established that the second messenger cyclic di-GMP (c-di-GMP) is required for the activation of glp expression, while an alternative sigma factor RpoS acts as a negative regulator for glp expression. In the present study, we report identification of a cis element within the 5´ untranslated region of glp that exerts negative regulation of glp expression. Further genetic screen of known and predicted DNA-binding proteins encoded in the genome of B. burgdorferi uncovered that overexpressing Borrelia host adaptation regulator (BadR), a known global regulator, dramatically reduced glp expression. Similarly, the badR mutant significantly increased glp expression. Subsequent electrophoretic mobility shift assay analyses demonstrated that BadR directly binds to this cis element, thereby repressing glp independent of RpoS-mediated repression. The efficiency of BadR binding was further assessed in the presence of c-di-GMP and various carbohydrates. This finding highlights multi-layered positive and negative regulatory mechanisms employed by B. burgdorferi to synchronize glp expression throughout its enzootic cycle.IMPORTANCEBorreliella burgdorferi, the Lyme disease pathogen, must modulate its gene expression differentially to adapt successfully to its two disparate hosts. Previous studies have demonstrated that the glycerol uptake and utilization operon, glpFKD, plays a crucial role in spirochetal survival within ticks. However, the glpFKD expression must be repressed when B. burgdorferi transitions to the mammalian host. In this study, we identified a specific cis element responsible for the repression of glpFKD. We further pinpointed Borrelia host adaptation regulator as the direct binding protein to this cis element, thereby repressing glpFKD expression. This discovery paves the way for a deeper exploration of how zoonotic pathogens sense distinct hosts and switch their carbon source utilization during transmission.
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Affiliation(s)
- Jun-Jie Zhang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Qian Wang
- Department of Clinical Laboratory, Wenzhou People’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Raj Priya
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Fuad Alanazi
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - 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, Zhejiang, China
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Sloupenska K, Koubkova B, Horak P, Dolezilkova J, Hutyrova B, Racansky M, Miklusova M, Mares J, Raska M, Krupka M. Antigenicity and immunogenicity of different morphological forms of Borrelia burgdorferi sensu lato spirochetes. Sci Rep 2024; 14:4014. [PMID: 38369537 PMCID: PMC10874929 DOI: 10.1038/s41598-024-54505-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/13/2024] [Indexed: 02/20/2024] Open
Abstract
Borrelia burgdorferi sensu lato is a species complex of pleomorphic spirochetes, including species that cause Lyme disease (LD) in humans. In addition to classic spiral forms, these bacteria are capable of creating morphological forms referred to as round bodies and aggregates. The subject of discussion is their possible contribution to the persistence of infection or post-infection symptoms in LD. This study investigates the immunological properties of these forms by monitoring reactivity with early (n = 30) and late stage (n = 30) LD patient sera and evaluating the immune response induced by vaccination of mice. In patient sera, we found a quantitative difference in reactivity with individual morphotypes, when aggregates were recognized most intensively, but the difference was statistically significant in only half of the tested strains. In post-vaccination mouse sera, we observed a statistically significant higher reactivity with antigens p83 and p25 (OspC) in mice vaccinated with aggregates compared to mice vaccinated with spiral forms. The importance of the particulate nature of the antigen for the induction of a Th1-directed response has also been demonstrated. In any of morphological forms, the possibility of inducing antibodies cross-reacting with human nuclear and myositis specific/associated autoantigens was not confirmed by vaccination of mice.
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Affiliation(s)
- Kristyna Sloupenska
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic
| | - Barbora Koubkova
- Department of Allergology and Clinical Immunology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
| | - Pavel Horak
- Third Department of Internal Medicine-Nephrology, Rheumatology and Endocrinology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
- Third Department of Internal Medicine-Nephrology, Rheumatology and Endocrinology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic
| | - Jana Dolezilkova
- Laboratory of Medical Parasitology and Zoology, Public Health Institute Ostrava, Partyzanske Namesti 2633/7, Moravska Ostrava, 702 00, Ostrava, Czech Republic
| | - Beata Hutyrova
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic
- Department of Allergology and Clinical Immunology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
| | - Mojmir Racansky
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic
- Department of Allergology and Clinical Immunology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
| | - Martina Miklusova
- Department of Neurology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
| | - Jan Mares
- Department of Neurology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
- Department of Neurology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic
| | - Milan Raska
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic
- Department of Immunology, University Hospital Olomouc, Zdravotniku 248/7, 779 00, Olomouc, Czech Republic
| | - Michal Krupka
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 779 00, Olomouc, Czech Republic.
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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. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.574763. [PMID: 38260690 PMCID: PMC10802411 DOI: 10.1101/2024.01.08.574763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
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 preferentially 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.
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Affiliation(s)
- Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Margie Kinnersley
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Diane M. Brooks
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Laura S. Hall
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Eric Luo
- Vaccine and Infectious Disease Organization, Saskatoon, SK, Canada
| | | | - Jenny Wachter
- Vaccine and Infectious Disease Organization, Saskatoon, SK, Canada
| | - D. Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
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7
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Alanazi F, Raghunandanan S, Priya R, Yang XF. The Rrp2-RpoN-RpoS pathway plays an important role in the blood-brain barrier transmigration of the Lyme disease pathogen. Infect Immun 2023; 91:e0022723. [PMID: 37874144 PMCID: PMC10652863 DOI: 10.1128/iai.00227-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 09/14/2023] [Indexed: 10/25/2023] Open
Abstract
Lyme disease, caused by Borrelia (or Borreliella) burgdorferi, is a complex multisystemic disorder that includes Lyme neuroborreliosis resulting from the invasion of both the central and peripheral nervous systems. However, factors that enable the pathogen to cross the blood-brain barrier (BBB) and invade the central nervous system (CNS) are still not well understood. The objective of this study was to identify the B. burgdorferi factors required for BBB transmigration. We utilized a transwell BBB model based on human brain-microvascular endothelial cells and focused on investigating the Rrp2-RpoN-RpoS pathway, a central regulatory pathway that is essential for mammalian infection by B. burgdorferi. Our results demonstrated that the Rrp2-RpoN-RpoS pathway is crucial for BBB transmigration. Furthermore, we identified OspC, a major surface lipoprotein controlled by the Rrp2-RpoN-RpoS pathway, as a significant contributor to BBB transmigration. Constitutive production of OspC in a mutant defective in the Rrp2-RpoN-RpoS pathway did not rescue the impairment in BBB transmigration, indicating that this pathway controls additional factors for this process. Two other major surface lipoproteins controlled by this pathway, DbpA/B and BBK32, appeared to be dispensable for BBB transmigration. In addition, both the surface lipoprotein OspA and the Rrp1 pathway, which are required B. burgdorferi colonization in the tick vector, were found not required for BBB transmigration. Collectively, our findings using in vitro transwell assays uncover another potential role of the Rrp2-RpoN-RpoS pathway in BBB transmigration of B. burgdorferi and invasion into the CNS.
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Affiliation(s)
- Fuad Alanazi
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Sajith Raghunandanan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Raj Priya
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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8
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Sapiro AL, Hayes BM, Volk RF, Zhang JY, Brooks DM, Martyn C, Radkov A, Zhao Z, Kinnersley M, Secor PR, Zaro BW, Chou S. Longitudinal map of transcriptome changes in the Lyme pathogen Borrelia burgdorferi during tick-borne transmission. eLife 2023; 12:RP86636. [PMID: 37449477 PMCID: PMC10393048 DOI: 10.7554/elife.86636] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
Borrelia burgdorferi (Bb), the causative agent of Lyme disease, adapts to vastly different environments as it cycles between tick vector and vertebrate host. During a tick bloodmeal, Bb alters its gene expression to prepare for vertebrate infection; however, the full range of transcriptional changes that occur over several days inside of the tick are technically challenging to capture. We developed an experimental approach to enrich Bb cells to longitudinally define their global transcriptomic landscape inside nymphal Ixodes scapularis ticks during a transmitting bloodmeal. We identified 192 Bb genes that substantially change expression over the course of the bloodmeal from 1 to 4 days after host attachment. The majority of upregulated genes encode proteins found at the cell envelope or proteins of unknown function, including 45 outer surface lipoproteins embedded in the unusual protein-rich coat of Bb. As these proteins may facilitate Bb interactions with the host, we utilized mass spectrometry to identify candidate tick proteins that physically associate with Bb. The Bb enrichment methodology along with the ex vivo Bb transcriptomes and candidate tick interacting proteins presented here provide a resource to facilitate investigations into key determinants of Bb priming and transmission during the tick stage of its unique transmission cycle.
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Affiliation(s)
- Anne L Sapiro
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Beth M Hayes
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Regan F Volk
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San FranciscoSan FranciscoUnited States
| | - Jenny Y Zhang
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Diane M Brooks
- Division of Biological Sciences, University of MontanaMissoulaUnited States
| | - Calla Martyn
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Atanas Radkov
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Ziyi Zhao
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Margie Kinnersley
- Division of Biological Sciences, University of MontanaMissoulaUnited States
| | - Patrick R Secor
- Division of Biological Sciences, University of MontanaMissoulaUnited States
| | - Balyn W Zaro
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San FranciscoSan FranciscoUnited States
| | - Seemay Chou
- Department of Biochemistry & Biophysics, University of California, San FranciscoSan FranciscoUnited States
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9
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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.
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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
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10
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Steingard CH, Helmann JD. Meddling with Metal Sensors: Fur-Family Proteins as Signaling Hubs. J Bacteriol 2023; 205:e0002223. [PMID: 37010421 PMCID: PMC10127796 DOI: 10.1128/jb.00022-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023] Open
Abstract
The ferric uptake regulator (Fur) protein is the founding member of the FUR superfamily of metalloregulatory proteins that control metal homeostasis in bacteria. FUR proteins regulate metal homeostasis in response to the binding of iron (Fur), zinc (Zur), manganese (Mur), or nickel (Nur). FUR family proteins are generally dimers in solution, but the DNA-bound complex can involve a single dimer, a dimer-of-dimers, or an extended array of bound protein. Elevated FUR levels due to changes in cell physiology increase DNA occupancy and may also kinetically facilitate protein dissociation. Interactions between FUR proteins and other regulators are commonplace, often including cooperative and competitive DNA-binding interactions within the regulatory region. Further, there are many emerging examples of allosteric regulators that interact directly with FUR family proteins. Here, we focus on newly uncovered examples of allosteric regulation by diverse Fur antagonists (Escherichia coli YdiV/SlyD, Salmonella enterica EIIANtr, Vibrio parahaemolyticus FcrX, Acinetobacter baumannii BlsA, Bacillus subtilis YlaN, and Pseudomonas aeruginosa PacT) as well as one Zur antagonist (Mycobacterium bovis CmtR). Small molecules and metal complexes may also serve as regulatory ligands, with examples including heme binding to Bradyrhizobium japonicum Irr and 2-oxoglutarate binding to Anabaena FurA. How these protein-protein and protein-ligand interactions act in conjunction with regulatory metal ions to facilitate signal integration is an active area of investigation.
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Affiliation(s)
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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11
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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.
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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
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12
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Grassmann AA, Tokarz R, Golino C, McLain MA, Groshong AM, Radolf JD, Caimano MJ. BosR and PlzA reciprocally regulate RpoS function to sustain Borrelia burgdorferi in ticks and mammals. J Clin Invest 2023; 133:e166710. [PMID: 36649080 PMCID: PMC9974103 DOI: 10.1172/jci166710] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
The RNA polymerase alternative σ factor RpoS in Borrelia burgdorferi (Bb), the Lyme disease pathogen, is responsible for programmatic-positive and -negative gene regulation essential for the spirochete's dual-host enzootic cycle. RpoS is expressed during tick-to-mammal transmission and throughout mammalian infection. Although the mammalian-phase RpoS regulon is well described, its counterpart during the transmission blood meal is unknown. Here, we used Bb-specific transcript enrichment by tick-borne disease capture sequencing (TBDCapSeq) to compare the transcriptomes of WT and ΔrpoS Bb in engorged nymphs and following mammalian host-adaptation within dialysis membrane chambers. TBDCapSeq revealed dramatic changes in the contours of the RpoS regulon within ticks and mammals and further confirmed that RpoS-mediated repression is specific to the mammalian-phase of Bb's enzootic cycle. We also provide evidence that RpoS-dependent gene regulation, including repression of tick-phase genes, is required for persistence in mice. Comparative transcriptomics of engineered Bb strains revealed that the Borrelia oxidative stress response regulator (BosR), a noncanonical Fur family member, and the cyclic diguanosine monophosphate (c-di-GMP) effector PlzA reciprocally regulate the function of RNA polymerase complexed with RpoS. BosR is required for RpoS-mediated transcription activation and repression in addition to its well-defined role promoting transcription of rpoS by the RNA polymerase alternative σ factor RpoN. During transmission, ligand-bound PlzA antagonizes RpoS-mediated repression, presumably acting through BosR.
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Affiliation(s)
| | - Rafal Tokarz
- Center for Infection and Immunity and
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Caroline Golino
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
| | | | - Ashley M. Groshong
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Pediatrics
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Pediatrics
- Department of Molecular Biology and Biophysics
- Department of Genetics and Genome Sciences, and
- Department of Immunology, UConn Health, Farmington, Connecticut, USA
| | - Melissa J. Caimano
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Pediatrics
- Department of Molecular Biology and Biophysics
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13
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Saylor TC, Savage CR, Krusenstjerna AC, Jusufovic N, Zückert WR, Brissette CA, Motaleb M, Schlax PJ, Stevenson B. Quantitative analyses of interactions between SpoVG and RNA/DNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527361. [PMID: 36860938 PMCID: PMC9976275 DOI: 10.1101/2023.02.06.527361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The Borrelia burgdorferi SpoVG protein has previously been found to be a DNA- and RNA-binding protein. To aid in the elucidation of ligand motifs, affinities for numerous RNAs, ssDNAs, and dsDNAs were measured and compared. The loci used in the study were spoVG, glpFKD, erpAB, bb0242, flaB, and ospAB, with particular focus on the untranslated 5' portion of the mRNAs. Performing binding and competition assays yielded that the 5' end of spoVG mRNA had the highest affinity while the lowest observed affinity was to the 5' end of flaB mRNA. Mutagenesis studies of spoVG RNA and ssDNA sequences suggested that the formation of SpoVG-nucleic acid complexes are not entirely dependent on either sequence or structure. Additionally, exchanging uracil for thymine in ssDNAs did not affect protein-nucleic acid complex formation.
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Affiliation(s)
- Timothy C. Saylor
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA
| | - Christina R. Savage
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA
| | - Andrew C. Krusenstjerna
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA
| | - Nerina Jusufovic
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA
| | - Wolfram R. Zückert
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Catherine A. Brissette
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Md. Motaleb
- Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
| | - Paula J. Schlax
- Department of Chemistry and Biochemistry, Bates College, Lewiston, ME, USA
| | - Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY, USA
- Department of Entomology, University of Kentucky, Lexington, KY, USA
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14
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Borreliella burgdorferi Antimicrobial-Tolerant Persistence in Lyme Disease and Posttreatment Lyme Disease Syndromes. mBio 2022; 13:e0344021. [PMID: 35467428 PMCID: PMC9239140 DOI: 10.1128/mbio.03440-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The annual incidence of Lyme disease, caused by tick-transmitted Borreliella burgdorferi, is estimated to be at least 476,000 cases in the United States and many more worldwide. Ten to 20% of antimicrobial-treated Lyme disease patients display posttreatment Lyme disease syndrome (PTLDS), a clinical complication whose etiology and pathogenesis remain uncertain. Autoimmunity, cross-reactivity, molecular mimicry, coinfections, and borrelial tolerance to antimicrobials/persistence have been hypothesized and studied as potential causes of PTLDS. Studies of borrelial tolerance/persistence in vitro in response to antimicrobials and experimental studies in mice and nonhuman primates, taken together with clinical reports, have revealed that B. burgdorferi becomes tolerant to antimicrobials and may sometimes persist in animals and humans after the currently recommended antimicrobial treatment. Moreover, B. burgdorferi is pleomorphic and can generate viable-but-nonculturable bacteria, states also involved in antimicrobial tolerance. The multiple regulatory pathways and structural genes involved in mediating this tolerance to antimicrobials and environmental stressors by persistence might include the stringent (rel and dksA) and host adaptation (rpoS) responses, sugar metabolism (glpD), and polypeptide transporters (opp). Application of this recently reported knowledge to clinical studies can be expected to clarify the potential role of bacterial antibacterial tolerance/persistence in Lyme disease and PTLDS.
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15
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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.
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16
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Utilizing Two Borrelia bavariensis Isolates Naturally Lacking the PFam54 Gene Array To Elucidate the Roles of PFam54-Encoded Proteins. Appl Environ Microbiol 2022; 88:e0155521. [PMID: 34986011 DOI: 10.1128/aem.01555-21] [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: 11/20/2022] Open
Abstract
Lyme borreliosis is the most common vector-borne disease in the Northern Hemisphere, caused by spirochetes belonging to the Borrelia burgdorferi sensu lato species complex, which are transmitted by ixodid ticks. B. burgdorferi sensu lato species produce a family of proteins on the linear plasmid 54 (PFam54), some of which confer the functions of cell adhesion and inactivation of complement, the first line of host defense. However, the impact of PFam54 in promoting B. burgdorferi sensu lato pathogenesis remains unclear because of the hurdles to simultaneously knock out all PFam54 proteins in a spirochete. Here, we describe two Borrelia bavariensis strains, PBN and PNi, isolated from patients naturally lacking PFam54 but maintaining the rest of the genome with greater than 95% identity to the reference B. bavariensis strain, PBi. We found that PBN and PNi less efficiently survive in human serum than PBi. Such defects were restored by introducing two B. bavariensis PFam54 recombinant proteins, BGA66 and BGA71, confirming the role of these proteins in providing complement evasion of B. bavariensis. Further, we found that all three strains remain detectable in various murine tissues 21 days post-subcutaneous infection, supporting the nonessential role of B. bavariensis PFam54 in promoting spirochete persistence. This study identified and utilized isolates deficient in PFam54 to associate the defects with the absence of these proteins, building the foundation to further study the role of each PFam54 protein in contributing to B. burgdorferi sensu lato pathogenesis. IMPORTANCE To establish infections, Lyme borreliae utilize various means to overcome the host's immune system. Proteins encoded by the PFam54 gene array play a role in spirochete survival in vitro and in vivo. Moreover, this gene array has been described in all currently available Lyme borreliae genomes. By investigating the first two Borrelia bavariensis isolates naturally lacking the entire PFam54 gene array, we showed that both patient isolates display an increased susceptibility to human serum, which can be rescued in the presence of two PFam54 recombinant proteins. However, both isolates remain infectious to mice after intradermal inoculation, suggesting the nonessential role of PFam54 during the long-term, but may differ slightly in the colonization of specific tissues. Furthermore, these isolates show high genomic similarity to type strain PBi (>95%) and could be used in future studies investigating the role of each PFam54 protein in Lyme borreliosis pathogenesis.
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The evolving story of Borrelia burgdorferi sensu lato transmission in Europe. Parasitol Res 2022; 121:781-803. [PMID: 35122516 PMCID: PMC8816687 DOI: 10.1007/s00436-022-07445-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 01/19/2022] [Indexed: 12/13/2022]
Abstract
Beside mosquitoes, ticks are well-known vectors of different human pathogens. In the Northern Hemisphere, Lyme borreliosis (Eurasia, LB) or Lyme disease (North America, LD) is the most commonly occurring vector-borne infectious disease caused by bacteria of the genus Borrelia which are transmitted by hard ticks of the genus Ixodes. The reported incidence of LB in Europe is about 22.6 cases per 100,000 inhabitants annually with a broad range depending on the geographical area analyzed. However, the epidemiological data are largely incomplete, because LB is not notifiable in all European countries. Furthermore, not only differ reporting procedures between countries, there is also variation in case definitions and diagnostic procedures. Lyme borreliosis is caused by several species of the Borrelia (B.) burgdorferi sensu lato (s.l.) complex which are maintained in complex networks including ixodid ticks and different reservoir hosts. Vector and host influence each other and are affected by multiple factors including climate that have a major impact on their habitats and ecology. To classify factors that influence the risk of transmission of B. burgdorferi s.l. to their different vertebrate hosts as well as to humans, we briefly summarize the current knowledge about the pathogens including their astonishing ability to overcome various host immune responses, regarding the main vector in Europe Ixodes ricinus, and the disease caused by borreliae. The research shows, that a higher standardization of case definition, diagnostic procedures, and standardized, long-term surveillance systems across Europe is necessary to improve clinical and epidemiological data.
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18
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Groshong AM, Grassmann AA, Luthra A, McLain MA, Provatas AA, Radolf JD, Caimano MJ. PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi. PLoS Pathog 2021; 17:e1009725. [PMID: 34265024 PMCID: PMC8323883 DOI: 10.1371/journal.ppat.1009725] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 07/30/2021] [Accepted: 06/18/2021] [Indexed: 02/05/2023] Open
Abstract
In this study, we examined the relationship between c-di-GMP and its only known effector protein, PlzA, in Borrelia burgdorferi during the arthropod and mammalian phases of the enzootic cycle. Using a B. burgdorferi strain expressing a plzA point mutant (plzA-R145D) unable to bind c-di-GMP, we confirmed that the protective function of PlzA in ticks is c-di-GMP-dependent. Unlike ΔplzA spirochetes, which are severely attenuated in mice, the plzA-R145D strain was fully infectious, firmly establishing that PlzA serves a c-di-GMP-independent function in mammals. Contrary to prior reports, loss of PlzA did not affect expression of RpoS or RpoS-dependent genes, which are essential for transmission, mammalian host-adaptation and murine infection. To ascertain the nature of PlzA's c-di-GMP-independent function(s), we employed infection models using (i) host-adapted mutant spirochetes for needle inoculation of immunocompetent mice and (ii) infection of scid mice with in vitro-grown organisms. Both approaches substantially restored ΔplzA infectivity, suggesting that PlzA enables B. burgdorferi to overcome an early bottleneck to infection. Furthermore, using a Borrelia strain expressing a heterologous, constitutively active diguanylate cyclase, we demonstrate that 'ectopic' production of c-di-GMP in mammals abrogates spirochete virulence and interferes with RpoS function at the post-translational level in a PlzA-dependent manner. Structural modeling and SAXS analysis of liganded- and unliganded-PlzA revealed marked conformational changes that underlie its biphasic functionality. This structural plasticity likely enables PlzA to serve as a c-di-GMP biosensor that in its respective liganded and unliganded states promote vector- and host-adaptation by the Lyme disease spirochete.
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Affiliation(s)
- Ashley M. Groshong
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
| | - André A. Grassmann
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Melissa A. McLain
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
| | - Anthony A. Provatas
- Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, Connecticut, United States of America
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, United States of America
- Department of Genetics and Genome Science, UConn Health, Farmington, Connecticut, United States of America
- Department of Immunology, UConn Health, Farmington, Connecticut, United States of America
| | - Melissa J. Caimano
- Department of Medicine, UConn Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, UConn Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, United States of America
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19
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Singh A, Izac JR, Schuler EJA, Patel DT, Davies C, Marconi RT. High-resolution crystal structure of the Borreliella burgdorferi PlzA protein in complex with c-di-GMP: new insights into the interaction of c-di-GMP with the novel xPilZ domain. Pathog Dis 2021; 79:6297269. [PMID: 34117751 PMCID: PMC8240479 DOI: 10.1093/femspd/ftab030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 06/10/2021] [Indexed: 12/27/2022] Open
Abstract
In the tick-borne pathogens, Borreliella burgdorferi and Borrelia hermsii, c-di-GMP is produced by a single diguanylate cyclase (Rrp1). In these pathogens, the Plz proteins (PlzA, B and C) are the only c-di-GMP receptors identified to date and PlzA is the sole c-di-GMP receptor found in all Borreliella isolates. Bioinformatic analyses suggest that PlzA has a unique PilZN3-PilZ architecture with the relatively uncommon xPilZ domain. Here, we present the crystal structure of PlzA in complex with c-di-GMP (1.6 Å resolution). This is the first structure of a xPilz domain in complex with c-di-GMP to be determined. PlzA has a two-domain structure, where each domain comprises topologically equivalent PilZ domains with minimal sequence identity but remarkable structural similarity. The c-di-GMP binding site is formed by the linker connecting the two domains. While the structure of apo PlzA could not be determined, previous fluorescence resonance energy transfer data suggest that apo and holo forms of the protein are structurally distinct. The information obtained from this study will facilitate ongoing efforts to identify the molecular mechanisms of PlzA-mediated regulation in ticks and mammals.
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Affiliation(s)
- Avinash Singh
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Jerilyn R Izac
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, 1112 East Clay Street, Room 101 McGuire Hall, Richmond, VA 23298-0678, USA
| | - Edward J A Schuler
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, 1112 East Clay Street, Room 101 McGuire Hall, Richmond, VA 23298-0678, USA
| | - Dhara T Patel
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, 1112 East Clay Street, Room 101 McGuire Hall, Richmond, VA 23298-0678, USA
| | - Christopher Davies
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Richard T Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, 1112 East Clay Street, Room 101 McGuire Hall, Richmond, VA 23298-0678, USA
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