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Foor SD, Brangulis K, Shakya AK, Rana VS, Bista S, Kitsou C, Ronzetti M, Alreja AB, Linden SB, Altieri AS, Baljinnyam B, Akopjana I, Nelson DC, Simeonov A, Herzberg O, Caimano MJ, Pal U. A unique borrelial protein facilitates microbial immune evasion. mBio 2023; 14:e0213523. [PMID: 37830812 PMCID: PMC10653885 DOI: 10.1128/mbio.02135-23] [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: 08/10/2023] [Accepted: 08/14/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Lyme disease is a major tick-borne infection caused by a bacterial pathogen called Borrelia burgdorferi, which is transmitted by ticks and affects hundreds of thousands of people every year. These bacterial pathogens are distinct from other genera of microbes because of their distinct features and ability to transmit a multi-system infection to a range of vertebrates, including humans. Progress in understanding the infection biology of Lyme disease, and thus advancements towards its prevention, are hindered by an incomplete understanding of the microbiology of B. burgdorferi, partly due to the occurrence of many unique borrelial proteins that are structurally unrelated to proteins of known functions yet are indispensable for pathogen survival. We herein report the use of diverse technologies to examine the structure and function of a unique B. burgdorferi protein, annotated as BB0238-an essential virulence determinant. We show that the protein is structurally organized into two distinct domains, is involved in multiplex protein-protein interactions, and facilitates tick-to-mouse pathogen transmission by aiding microbial evasion of early host cellular immunity. We believe that our findings will further enrich our understanding of the microbiology of B. burgdorferi, potentially impacting the future development of novel prevention strategies against a widespread tick-transmitted infection.
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Affiliation(s)
- Shelby D. Foor
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Kalvis Brangulis
- Latvian Biomedical Research and Study Centre, Riga, Latvia
- Department of Human Physiology and Biochemistry, Riga Stradins University, Riga, Latvia
| | - Anil K. Shakya
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
| | - Vipin S. Rana
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Sandhya Bista
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Chrysoula Kitsou
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
| | - Michael Ronzetti
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Adit B. Alreja
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
| | - Sara B. Linden
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
| | - Amanda S. Altieri
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
| | - Bolormaa Baljinnyam
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Inara Akopjana
- Latvian Biomedical Research and Study Centre, Riga, Latvia
| | - Daniel C. Nelson
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Osnat Herzberg
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, USA
| | - Melissa J. Caimano
- Departments of Medicine, Pediatrics, and Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Utpal Pal
- Department of Veterinary Medicine, University of Maryland, College Park, Maryland, USA
- Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
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Controlled Proteolysis of an Essential Virulence Determinant Dictates Infectivity of Lyme Disease Pathogens. Infect Immun 2022; 90:e0005922. [PMID: 35416705 DOI: 10.1128/iai.00059-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Borrelia burgdorferi BB0323 protein undergoes a complex yet poorly defined proteolytic maturation event that generates N-terminal and C-terminal proteins with essential functions in cell growth and infection. Here, we report that a borrelial protease, B. burgdorferi high temperature requirement A protease (BbHtrA), cleaves BB0323 between asparagine (N) and leucine (L) at positions 236 and 237, while the replacement of these residues with alanine in the mutant protein prevents its cleavage, despite preserving its normal secondary structure. The N-terminal BB0323 protein binds BbHtrA, but its cleavage site mutant displays deficiency in such interaction. An isogenic borrelial mutant with NL-to-AA substitution in BB0323 (referred to as Bbbb0323NL) maintains normal growth yet is impaired for infection of mice or transmission from infected ticks. Notably, the BB0323 protein is still processed in Bbbb0323NL, albeit with lower levels of mature N-terminal BB0323 protein and multiple aberrantly processed polypeptides, which could result from nonspecific cleavages at other asparagine and leucine residues in the protein. The lack of infectivity of Bbbb0323NL is likely due to the impaired abundance or stoichiometry of a protein complex involving BB0238, another spirochete protein. Together, these studies highlight that a precise proteolytic event and a particular protein-protein interaction, involving multiple borrelial virulence determinants, are mutually inclusive and interconnected, playing essential roles in the infectivity of Lyme disease pathogens.
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Membrane directed expression in Escherichia coli of BBA57 and other virulence factors from the Lyme disease agent Borrelia burgdorferi. Sci Rep 2019; 9:17606. [PMID: 31772280 PMCID: PMC6879480 DOI: 10.1038/s41598-019-53830-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 11/05/2019] [Indexed: 12/22/2022] Open
Abstract
Membrane-embedded proteins are critical to the establishment, survival and persistence in the host of the Lyme disease bacterium Borrelia burgdorferi (Bb), but to date, there are no solved structures of transmembrane proteins representing these attractive therapeutic targets. All available structures from the genus Borrelia represent proteins expressed without a membrane-targeting signal peptide, thus avoiding conserved pathways that modify, fold and assemble membrane protein complexes. Towards elucidating structure and function of these critical proteins, we directed translocation of eleven expression-optimized Bb virulence factors, including the signal sequence, to the Escherichia coli membrane, of which five, BBA57, HtrA, BB0238, BB0323, and DipA, were expressed with C-terminal His-tags. P66 was also expressed using the PelB signal sequence fused to maltose binding protein. Membrane-associated BBA57 lipoprotein was solubilized by non-ionic and zwitterionic detergents. We show BBA57 translocation to the outer membrane, purification at a level sufficient for structural studies, and evidence for an α-helical multimer. Previous studies showed multiple critical roles of BBA57 in transmission, joint arthritis, carditis, weakening immune responses, and regulating other Bb outer surface proteins. In describing the first purification of membrane-translocated BBA57, this work will support subsequent studies that reveal the precise mechanisms of this important Lyme disease virulence factor.
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