Lyme disease is the most reported vector-borne disease in the United States. The causative agent, Borrelia burgdorferi (Bb), is an obligate pathogenic spirochete that is transmitted via a tick bite. How Bb is maintained in its enzootic cycle between mammals and ticks is poorly understood; yet, this understanding is critical for developing innovative approaches to disrupt the tick-mammal-tick natural cycle. We and others have identified a two-component signal transduction system, Hk1-Rrp1, that is essential for Bb survival in the tick. Rrp1is a response regulator possessing diguanylate cyclase (DGC) activity that produces cyclic dimeric GMP (c-di-GMP), a new bacterial second messenger that controls the switch between the motile, single-cellular lifestyle and the sessile, multicellular lifestyle (biofilms). We discovered that c-di-GMP-mediated signaling controls a catabolic switch from glucose to glycerol upon the transition from the mammal to the tick, by regulating the transcription of the glp operon for glycerol transport and utilization which are critical for spirochete survival in ticks. Further, we found that the c-di-GMP-binding effector protein PlzA, previously known to influence Bb motility, also controls glp expression as well as synthesis of multiple virulence factors. We hypothesize that, because of the small genome and streamlined regulatory repertoire, Bb employs the same c-di-GMP effector protein, PlzA, or a protein that interacts with PlzA, to coordinate diverse processes (motility, catabolism, virulence) that are involved in the mammal-to-tick transition. To test this hypothesis and to to understand the role of c-di-GMP signaling in the mammal-to-arthropod host transition, we have formulated the following Specific Aims: (1) Elucidate the mechanism of regulation of the glycerol metabolism and virulence by the c-di-GMP- binding protein PlzA in Bb; (2) Identify and characterize new c-di-GMP-binding effector proteins in Bb and interrogate their role in survival in the tick. Outcomes will uncover novel processes underlying the mammal-to-arthropod host transition, novel c-di-GMP effector proteins and new c-di-GMP signaling paradigm.

Public Health Relevance

Lyme disease remains the No. 1 reported vector-borne disease in the US. The insights on c-di- GMP-dependent regulation of the mammal-to-arthropod host transition that will emerge from this application are expected to guide the development of new strategies to control the spread of vector- borne bacterial pathogens and to manage diseases caused by these pathogens.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI117198-02
Application #
8994274
Study Section
Special Emphasis Panel (ZRG1-IDM-B (80))
Program Officer
Ilias, Maliha R
Project Start
2015-01-15
Project End
2016-12-31
Budget Start
2016-01-01
Budget End
2016-12-31
Support Year
2
Fiscal Year
2016
Total Cost
$187,750
Indirect Cost
$42,000
Name
Indiana University-Purdue University at Indianapolis
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
603007902
City
Indianapolis
State
IN
Country
United States
Zip Code
46202
Zhang, Jun-Jie; Chen, Tong; Yang, Youyun et al. (2018) Positive and Negative Regulation of Glycerol Utilization by the c-di-GMP Binding Protein PlzA in Borrelia burgdorferi. J Bacteriol 200:
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Yin, Yanping; Yang, Youyun; Xiang, Xuwu et al. (2016) Insight into the Dual Functions of Bacterial Enhancer-Binding Protein Rrp2 of Borrelia burgdorferi. J Bacteriol 198:1543-52
Ye, Meiping; Zhou, Yan; Lou, Yongliang et al. (2016) Genome reduction of Borrelia burgdorferi: two TCS signaling pathways for two distinct host habitats. Sci China Life Sci 59:19-21
Carrasco, Sebastian E; Yang, Youyun; Troxell, Bryan et al. (2015) Borrelia burgdorferi elongation factor EF-Tu is an immunogenic protein during Lyme borreliosis. Emerg Microbes Infect 4:e54
Carrasco, Sebastian E; Troxell, Bryan; Yang, Youyun et al. (2015) Outer surface protein OspC is an antiphagocytic factor that protects Borrelia burgdorferi from phagocytosis by macrophages. Infect Immun 83:4848-60