The bacterium Borrelia burgdorferi is a causative agent of Lyme disease. B. burgdorferi can synthesize several different outer surface proteins that are involved in pathogenesis or transmission during the enzootic cycle. The regulation of outer surface protein synthesis is not well understood at the molecular level. This application proposes to evaluate the hypothesis that cis-acting factors, such as DNA supercoiling, and trans-acting factors, such as DNA-binding repressor proteins, regulate the expression of outer surface protein genes in response to environmental signals. Production of outer surface proteins OspA and OspC is reciprocally regulated, which may be how B. burgdorferi adapts to the different environments of the tick vector and mammalian host or effects transmission between the environments. An ospAB operon promoter-specific trans-acting protein is hypothesized to repress ospAB transcription. The regulatory protein will be purified and identified. Cis-acting sequences in the ospAB promoter region are hypothesized to mediate transcriptional regulation. These sites will be mapped and characterized. The architectural DNA-binding protein Hbb is hypothesized to facilitate regulation of ospC expression. The function of Hbb will be probed by mutagenesis of the hbb gene and the Hbb binding site in the ospC promoter region. The ospC promoter will be replaced with an inducible promoter system to control cellular OspC levels without perturbing DNA supercoiling so that the coupling of ospC and ospAB transcription can be studied. ospC gene expression from the flac hybrid promoter is hypothesized to be regulated by IPTG and to influence ospAB operon expression. The mechanism by which DNA supercoiling regulates ospC expression is hypothesized to involve Hbb and specific sequence motifs in the ospC promoter region. Mutant ospC promoters will be constructed. The transcriptional response of these mutants to temperature and DNA supercoiling will be assayed in order to define the cis-acting elements responsible for regulation. The long-term objective of these studies is to understand the mechanism of outer surface protein gene regulation in response to environmental signals.
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| Drecktrah, Dan; Samuels, D Scott (2018) Genetic Manipulation of Borrelia Spp. Curr Top Microbiol Immunol 415:113-140 |
| Anacker, Melissa L; Drecktrah, Dan; LeCoultre, Richard D et al. (2018) RNase III Processing of rRNA in the Lyme Disease Spirochete Borrelia burgdorferi. J Bacteriol 200: |
| Samuels, D Scott; Drecktrah, Dan; Hall, Laura S (2018) Genetic Transformation and Complementation. Methods Mol Biol 1690:183-200 |
| Lybecker, Meghan C; Samuels, D Scott (2017) Small RNAs of Borrelia burgdorferi: Characterizing Functional Regulators in a Sea of sRNAs?. Yale J Biol Med 90:317-323 |
| Caimano, Melissa J; Drecktrah, Dan; Kung, Faith et al. (2016) Interaction of the Lyme disease spirochete with its tick vector. Cell Microbiol 18:919-27 |
| Samuels, D Scott; Samuels, Leah R N (2016) Gene Regulation During the Enzootic Cycle of the Lyme Disease Spirochete. For Immunopathol Dis Therap 7:205-212 |
| Drecktrah, Dan; Lybecker, Meghan; Popitsch, Niko et al. (2015) The Borrelia burgdorferi RelA/SpoT Homolog and Stringent Response Regulate Survival in the Tick Vector and Global Gene Expression during Starvation. PLoS Pathog 11:e1005160 |
| Drecktrah, Dan; Hall, Laura S; Hoon-Hanks, Laura L et al. (2013) An inverted repeat in the ospC operator is required for induction in Borrelia burgdorferi. PLoS One 8:e68799 |
| Imai, Denise M; Samuels, D Scott; Feng, Sunlian et al. (2013) The early dissemination defect attributed to disruption of decorin-binding proteins is abolished in chronic murine Lyme borreliosis. Infect Immun 81:1663-73 |
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