Vector-borne pathogens such as Borrelia burgdorferi, the agent of Lyme disease, produce different proteins during infection of the mammalian host and the arthropod vector. These include distinct surface proteins to interact with the variety of tissues that are encountered. In addition, vector-borne bacteria must sense when thevectorisfeedingonahost,andefficientlycoordinatetransmissionprocesses. We discovered that several key infection-associated proteins that are produced during tick feeding and transmission can be induced in culture by increasing the rate of bacterial replication. A model proposes that this correspondstothedramatic increase in growth rate of B. burgdorferi whenatick begins tofeed onblood. We found that the master regulator of chromosomal replication, the DnaA protein, binds adjacent to the transcriptional promoters of loci that encode two global regulatory proteins. Both of those regulatory proteins directtheproductionofsurfaceproteinsthatcontributetomammalianinfectionprocesses.DnaAhomologsare known to regulate transcription in E. coli and other bacterial species. We hypothesize that DnaA serves to connectborrelialreplicationwithproductionofinfection-associatedproteins. The planned studies will critically test that hypothesis by identifying DnaA-binding sites throughout the B. burgdorferi genome by chromatin immunoprecipitation - sequencing (ChIP-Seq), characterizing new DnaA- regulatedloci,andbiochemicallydefiningfactorsinvolvedwithDnaA-binding. Altogether, results ofthese studies will characterizea novel regulon of theLyme diseasespirochete,providing substantialnewinsightonthebacteria?sphysiologyandinfectiousmechanisms.

Public Health Relevance

During transmission from tick-to-mammal, the Lyme disease spirochete, Borrelia burgdorferi, produces a distinct repertoire of surface proteins that are critical for mammalian infection. Our studies indicate that the master controller of B. burgdorferi chromosomal replication, the DnaA protein, is involved with regulation of at least some of those transmission-induced proteins. The proposed studies will identify DnaA-binding sites throughout the B. burgdorferi genome, functionally characterize novel DnaA-regulated loci, and biochemically definethemechanismsbywhichDnaAinteractswithitstargetDNAs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI147139-01A1
Application #
9984651
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Ilias, Maliha R
Project Start
2020-02-14
Project End
2022-01-31
Budget Start
2020-02-14
Budget End
2021-01-31
Support Year
1
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Kentucky
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40526