Both non-pathogenic and pathogenic Burkholderia, including members of the opportunistic infection-causing Burkholderia cepacia complex, encode genes to produce contact-dependent growth inhibition (CDI) system proteins. CDI is a widespread phenomenon in which Gram-negative bacteria use the toxic C-terminus of a polymorphic surface-exposed exoprotein to inhibit the growth of susceptible bacteria upon cell-cell contact. The exoprotein toxin is delivered to the cytoplasm of target cells and autoinhibition is prevented by production of a small immunity protein. We previously demonstrated that, in addition to their role in interbacterial competition, the CDI system proteins in Burkholderia thailandensis, encoded by bcpAIOB, mediate biofilm formation. This requires the putative nuclease activity of the BcpA toxic exoprotein, but is independent of interbacterial killing, suggesting that biofilm formation in B. thailandensis involves an uncharacterized function of BcpA. Preliminary data suggest that bcpAIOB mediate interbacterial signaling in B. thailandensis, leading to a change in gene expression in immune target bacteria. Given these data and the conservation of CDI systems, it seems likely that CDI systems in other Burkholderia also function in interbacterial signaling and could play a role during infection. Toward understanding the role of CDI system-mediated signaling, this proposal will test the hypothesis that BcpA toxin delivered to an immune target cell interacts with specific periplasmic and cytoplasmic factors, leading to global gene expression changes, and represents a useful therapeutic target in pathogenic Burkholderia. Experiments proposed in Aim 1 will continue to investigate the mechanism of bcpAIOB-mediated interbacterial signaling in B. thailandensis, defining the affected gene regulation pathways and identifying required regions of BcpA, as well as other factors necessary for signaling. Studies in Aim 2 will explore the role of CDI systems and their potential for exploitation as therapies in pathogenic Burkholderia cepacia complex strains. These studies represent the first investigation of what may be a widespread phenomenon in Gram-negative bacteria and will work toward addressing an essential need for new drug targets and antimicrobials.

Public Health Relevance

Burkholderia are a group of environmental bacteria that can cause life-threatening opportunistic infections in patients with cystic fibrosis or other lung disorders. This proposal focuses on understanding of how these and related bacteria interact with each other and how that interaction may affect disease. Additionally, by studying antibacterial proteins produced by these bacteria, this research will lay the foundation for the development of new antimicrobial therapies against Burkholderia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Career Transition Award (K22)
Project #
1K22AI118949-01
Application #
8947449
Study Section
Microbiology and Infectious Diseases B Subcommittee (MID)
Program Officer
Mukhopadhyay, Suman
Project Start
2016-08-01
Project End
2018-07-31
Budget Start
2016-08-01
Budget End
2017-07-31
Support Year
1
Fiscal Year
2016
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
40506
Garcia, Erin C (2018) Contact-dependent interbacterial toxins deliver a message. Curr Opin Microbiol 42:40-46
Garcia, Erin C (2017) Burkholderia thailandensis: Genetic Manipulation. Curr Protoc Microbiol 45:4C.2.1-4C.2.15
Danka, Elizabeth S; Garcia, Erin C; Cotter, Peggy A (2017) Are CDI Systems Multicolored, Facultative, Helping Greenbeards? Trends Microbiol 25:391-401
Garcia, Erin C; Cotter, Peggy A (2016) Burkholderia thailandensis: Growth and Laboratory Maintenance. Curr Protoc Microbiol 42:4C.1.1-7