TY - JOUR
T1 - Assessing the Contribution of an HtrA Family Serine Protease During Borrelia turicatae Mammalian Infection
AU - Jackson-Litteken, Clay D.
AU - Zalud, Amanda K.
AU - Ratliff, C. Tyler
AU - Latham, Jacob I.
AU - Bourret, Travis J.
AU - Lopez, Job E.
AU - Blevins, Jon S.
N1 - Funding Information:
We acknowledge Daniel Voth for his helpful discussions and Brendan Moore, Marissa Fullerton, and Daniel Stuckey for experimental assistance. We also thank Brittany Armstrong and Aparna Krishnavajhala for their assistance with the qPCR-based bacterial burden assays. Finally, we would also like to acknowledge Allen Gies in the UAMS DNA Sequencing Core Facility and Alan Tackett and Sam Mackintosh in the UAMS Proteomic Core Facility for technical assistance. Funding. This research was supported by funding to JB through the UAMS Center for Microbial Pathogenesis and Host Inflammatory Responses (NIGMS P20-GM103625), the Arkansas Biosciences Institute (major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000), Barton Research Endowment, and the UAMS Vice Chancellor for Research pilot award, as well as by startup funds from Creighton University to TB.
Publisher Copyright:
© Copyright © 2019 Jackson-Litteken, Zalud, Ratliff, Latham, Bourret, Lopez and Blevins.
PY - 2019/8/13
Y1 - 2019/8/13
N2 - Tick-borne relapsing fever (TBRF), characterized by recurring febrile episodes, is globally distributed and among the most common bacterial infections in some African countries. Despite the public health concern that this disease represents, little is known regarding the virulence determinants required by TBRF Borrelia during infection. Because the chromosomes of TBRF Borrelia show extensive colinearity with those of Lyme disease (LD) Borrelia, the exceptions represent unique genes encoding proteins that are potentially essential to the disparate enzootic cycles of these two groups of spirochetes. One such exception is a gene encoding an HtrA family protease, BtpA, that is present in TBRF Borrelia, but not in LD spirochetes. Previous work suggested that btpA orthologs may be important for resistance to stresses faced during mammalian infection. Herein, proteomic analyses of the TBRF spirochete, Borrelia turicatae, demonstrated that BtpA, as well as proteins encoded by adjacent genes in the B. turicatae genome, were produced in response to culture at mammalian body temperature, suggesting a role in mammalian infection. Further, transcriptional analyses revealed that btpA was expressed with the genes immediately upstream and downstream as part of an operon. To directly assess if btpA is involved in resistance to environmental stresses, btpA deletion mutants were generated. btpA mutants demonstrated no growth defect in response to heat shock, but were more sensitive to oxidative stress produced by t-butyl peroxide compared to wild-type B. turicatae. Finally, btpA mutants were fully infectious in a murine relapsing fever (RF) infection model. These results indicate that BtpA is either not required for mammalian infection, or that compensatory mechanisms exist in TBRF spirochetes to combat environmental stresses encountered during mammalian infection in the absence of BtpA.
AB - Tick-borne relapsing fever (TBRF), characterized by recurring febrile episodes, is globally distributed and among the most common bacterial infections in some African countries. Despite the public health concern that this disease represents, little is known regarding the virulence determinants required by TBRF Borrelia during infection. Because the chromosomes of TBRF Borrelia show extensive colinearity with those of Lyme disease (LD) Borrelia, the exceptions represent unique genes encoding proteins that are potentially essential to the disparate enzootic cycles of these two groups of spirochetes. One such exception is a gene encoding an HtrA family protease, BtpA, that is present in TBRF Borrelia, but not in LD spirochetes. Previous work suggested that btpA orthologs may be important for resistance to stresses faced during mammalian infection. Herein, proteomic analyses of the TBRF spirochete, Borrelia turicatae, demonstrated that BtpA, as well as proteins encoded by adjacent genes in the B. turicatae genome, were produced in response to culture at mammalian body temperature, suggesting a role in mammalian infection. Further, transcriptional analyses revealed that btpA was expressed with the genes immediately upstream and downstream as part of an operon. To directly assess if btpA is involved in resistance to environmental stresses, btpA deletion mutants were generated. btpA mutants demonstrated no growth defect in response to heat shock, but were more sensitive to oxidative stress produced by t-butyl peroxide compared to wild-type B. turicatae. Finally, btpA mutants were fully infectious in a murine relapsing fever (RF) infection model. These results indicate that BtpA is either not required for mammalian infection, or that compensatory mechanisms exist in TBRF spirochetes to combat environmental stresses encountered during mammalian infection in the absence of BtpA.
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UR - http://www.scopus.com/inward/citedby.url?scp=85071648298&partnerID=8YFLogxK
U2 - 10.3389/fcimb.2019.00290
DO - 10.3389/fcimb.2019.00290
M3 - Article
C2 - 31456953
AN - SCOPUS:85071648298
VL - 9
JO - Frontiers in cellular and infection microbiology
JF - Frontiers in cellular and infection microbiology
SN - 2235-2988
M1 - 290
ER -