TY - JOUR
T1 - DksA controls the response of the lyme disease spirochete borrelia burgdorferi to starvation
AU - Boyle, William K.
AU - Groshong, Ashley M.
AU - Drecktrah, Dan
AU - Boylan, Julie A.
AU - Gherardini, Frank C.
AU - Blevins, Jon S.
AU - Scott Samuels, D.
AU - Bourret, Travis J.
N1 - Funding Information:
This research was supported by funding to T.J.B. from Creighton University and grants from the National Center for Research Resources (grant 5P20RR016469) and the National Institute for General Medical Science (grant 8P20GM103427); funding to D.S.S. from the National Institute of Allergy and Infectious Diseases (grant R01AI051486); funding to J.S.B. through the Arkansas Biosciences Institute (major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000), grants NIH/NIAID R01-AI087678 and NIH/NIAID R21-AI 119532, as well as support through the UAMS Center for Microbial Pathogenesis and Host Inflammatory Responses (grant P20-GM103625); funding to A.M.G. from The Global Lyme Alliance Deborah and Mark Blackman Postdoctoral Fellowship; and funds from the Division of Intramural Research, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Funding Information:
We thank the Rocky Mountain Laboratories Genomics unit and Dan Sturdevant for RNA expression analysis by Affymetrix Gene Chip, and Amanda Zulad, Crystal Richards, Daniel Dulebohn, and Sandy Stewart for critical review of the manuscript. We also thank Britney Cheff for valuable discussions. D.D., D.S.S., F.C.G., J.A.B., W.K.B., and T.J.B. contributed to the conception and design of the study; A.M.G., J.S.B., W.K.B., and T.J.B. generated the bacterial strains required for the study; W.K.B. performed the data analysis and statistical tests and wrote the sections of the manuscript. All authors contributed to manuscript revision and read and approved the submitted version. This research was supported by funding to T.J.B. from Creighton University and grants from the National Center for Research Resources (grant 5P20RR016469) and the National Institute for General Medical Science (grant 8P20GM103427); funding to D.S.S. from the National Institute of Allergy and Infectious Diseases (grant R01AI051486); funding to J.S.B. through the Arkansas Biosciences Institute (major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000), grants NIH/NIAID R01-AI087678 and NIH/NIAID R21-AI 119532, as well as support through the UAMS Center for Microbial Pathogenesis and Host Inflammatory Responses (grant P20-GM103625); funding to A.M.G. from The Global Lyme Alliance Deborah and Mark Blackman Postdoctoral Fellowship; and funds from the Division of Intramural Research, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA. The funders were not involved in study design, data collection, analysis, or interpretation, writing of the manuscript, or decision on where to submit for publication. We declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher Copyright:
Copyright © 2019 Boyle et al.
PY - 2019/2/1
Y1 - 2019/2/1
N2 - 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% CO 2 , 3% O 2 ). 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. Transcrip-tomic analyses revealed a partial overlap between the DksA regulon and the regulon of Rel Bbu , 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.
AB - 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% CO 2 , 3% O 2 ). 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. Transcrip-tomic analyses revealed a partial overlap between the DksA regulon and the regulon of Rel Bbu , 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.
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U2 - 10.1128/JB.00582-18
DO - 10.1128/JB.00582-18
M3 - Article
C2 - 30478087
AN - SCOPUS:85060626715
VL - 201
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 4
M1 - e00582-18
ER -