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Davis MM, Brock AM, DeHart TG, Boribong BP, Lee K, McClune ME, Chang Y, Cramer N, Liu J, Jones CN, Jutras BL. The peptidoglycan-associated protein NapA plays an important role in the envelope integrity and in the pathogenesis of the lyme disease spirochete. PLoS Pathog 2021; 17:e1009546. [PMID: 33984073 PMCID: PMC8118282 DOI: 10.1371/journal.ppat.1009546] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/08/2021] [Indexed: 12/11/2022] Open
Abstract
The bacterial pathogen responsible for causing Lyme disease, Borrelia burgdorferi, is an atypical Gram-negative spirochete that is transmitted to humans via the bite of an infected Ixodes tick. In diderms, peptidoglycan (PG) is sandwiched between the inner and outer membrane of the cell envelope. In many other Gram-negative bacteria, PG is bound by protein(s), which provide both structural integrity and continuity between envelope layers. Here, we present evidence of a peptidoglycan-associated protein (PAP) in B. burgdorferi. Using an unbiased proteomics approach, we identified Neutrophil Attracting Protein A (NapA) as a PAP. Interestingly, NapA is a Dps homologue, which typically functions to bind and protect cellular DNA from damage during times of stress. While B. burgdorferi NapA is known to be involved in the oxidative stress response, it lacks the critical residues necessary for DNA binding. Biochemical and cellular studies demonstrate that NapA is localized to the B. burgdorferi periplasm and is indeed a PAP. Cryo-electron microscopy indicates that mutant bacteria, unable to produce NapA, have structural abnormalities. Defects in cell-wall integrity impact growth rate and cause the napA mutant to be more susceptible to osmotic and PG-specific stresses. NapA-linked PG is secreted in outer membrane vesicles and augments IL-17 production, relative to PG alone. Using microfluidics, we demonstrate that NapA acts as a molecular beacon-exacerbating the pathogenic properties of B. burgdorferi PG. These studies further our understanding of the B. burgdorferi cell envelope, provide critical information that underlies its pathogenesis, and highlight how a highly conserved bacterial protein can evolve mechanistically, while maintaining biological function.
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Affiliation(s)
- Marisela M. Davis
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Aaron M. Brock
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
- Molecular and Cellular Biology, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Tanner G. DeHart
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Brittany P. Boribong
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Katherine Lee
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Mecaila E. McClune
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Yunjie Chang
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, United States of America
| | - Nicholas Cramer
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, United States of America
| | - Caroline N. Jones
- Molecular and Cellular Biology, Virginia Tech, Blacksburg, Virginia, United States of America
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Brandon L. Jutras
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, Virginia, United States of America
- Molecular and Cellular Biology, Virginia Tech, Blacksburg, Virginia, United States of America
- Center for Emerging, Zoonotic and Arthropod-borne Pathogens, Virginia Tech, Blacksburg, Virginia, United States of America
- Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States of America
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