Flagella are natural rotary motors that promote swimming motility required by many bacterial pathogens to navigate environments, infect hosts to promote disease, and promote biofilm formation. Compared to peritrichous bacterial pathogens such as E. coli and Salmonella species, many significant pathogens including Campylobacter jejuni, Vibrio cholerae, Helicobacter pylori, and Pseudomonas aeruginosa produce only a very limited number of flagellar motors specifically at poles of a bacterial cell. Furthermore, these polar flagellar motors promote higher torque and greater velocity of motility compared to flagellar motors of peritrichous bacteria. Thus, alternative paradigms must exist to account for how polar flagellar motors form and function in bacterial pathogens. We have explored flagellar biogenesis in C. jejuni to discover new paradigms for how polarly-flagellated bacterial pathogens regulate flagellar gene transcription, spatially and numerically regulate flagellar biogenesis, and alter flagellar motor structure to power flagellar rotation for motility.We also found evidence for general conservation of these mechanisms in a range of polarly-flagellated pathogens. In this proposal, we will continue to use C. jejuni as a model system to understand how the flagellar motor, which is a universal virulence and colonization determinant, forms and functions in a wide range of polarly-flagellated bacterial pathogens. Our work will also continue to reveal how the bacterial flagellum functions beyond motility to influence signal transduction pathways, spatial organization of the bacterial cell, and cell division in C. jejuni.
n Aim 1, we will examine how conserved flagellar two-component regulatory systems (TCSs) of polarly-flagellated pathogens detect formation of the flagellar type III secretion system (T3SS) and surrounding ring structures to initiate signal transduction required for flagellar gene transcription. We will also exploit the natural engineering of T3SS formation to activation of the C. jejuni flagellar TCS to determine molecular requirements of proteins to form T3SSs in bacterial pathogens.
In Aim 2, we will explore how the conserved FlhG ATPase of polar flagellates and a possible unusual flagellar C ring composition function together to numerically regulate flagellar biogenesis and spatially control cell division in C. jejuni.
In Aim 3, we will exploit mutagenesis and electron cryotomography technologies to decipher the ordered biosynthetic pathway for formation of flagellar disk appendages, which are required for powering flagellar rotation and creation of a functional polar flagellar motor. Accomplishment of these aims will promote new insights for how: 1) TCSs detect and perceive stimuli for initiation of signal transduction required for flagellar gene expression; 2) conserved proteins initiate T3SS formation in bacterial pathogens; 3) bacteria numerically regulate polar flagellar motor biogenesis; 4) flagellar proteins are used in alternate biological activities such as signal transduction, cell division, and spatial organization of the cell; 5) polarly-flagellated pathogens employ disk appendages to diversify flagellar structure and power flagellar rotation to generate torque resulting in high velocities of motility.

Public Health Relevance

Flagellar motility is required for many pathogenic bacteria to infect hosts to promote disease and initiate biofilm formation to persist in hosts or environments. We discovered that polarly-flagellated bacterial pathogens evolved specific mechanisms for forming functional polar flagellar motors that include ordered transcription of flagellar genes, numerical and spatial regulation of flagellar motor biogenesis, and synthesis of unique appendages to power flagellar rotation and motility. The proposed research will use Campylobacter jejuni as a model system to further understand how polar flagellar motors form in a broad range of polarly-flagellated bacterial pathogens such as Vibrio cholerae, Pseudomonas aeruginosa, and Helicobacter pylori.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI065539-15
Application #
9955146
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Baqar, Shahida
Project Start
2005-07-01
Project End
2021-06-30
Budget Start
2020-07-01
Budget End
2021-06-30
Support Year
15
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Li, Jiaqi; Gulbronson, Connor J; Bogacz, Marek et al. (2018) FliW controls growth-phase expression of Campylobacter jejuni flagellar and non-flagellar proteins via the post-transcriptional regulator CsrA. Microbiology 164:1308-1319
Burnham, Peter M; Hendrixson, David R (2018) Campylobacter jejuni: collective components promoting a successful enteric lifestyle. Nat Rev Microbiol 16:551-565
Luethy, Paul M; Huynh, Steven; Ribardo, Deborah A et al. (2017) Microbiota-Derived Short-Chain Fatty Acids Modulate Expression of Campylobacter jejuni Determinants Required for Commensalism and Virulence. MBio 8:
Beeby, Morgan; Ribardo, Deborah A; Brennan, Caitlin A et al. (2016) Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold. Proc Natl Acad Sci U S A 113:E1917-26
Gulbronson, Connor J; Ribardo, Deborah A; Balaban, Murat et al. (2016) FlhG employs diverse intrinsic domains and influences FlhF GTPase activity to numerically regulate polar flagellar biogenesis in Campylobacter jejuni. Mol Microbiol 99:291-306
Fields, Joshua A; Li, Jiaqi; Gulbronson, Connor J et al. (2016) Campylobacter jejuni CsrA Regulates Metabolic and Virulence Associated Proteins and Is Necessary for Mouse Colonization. PLoS One 11:e0156932
Luethy, Paul M; Huynh, Steven; Parker, Craig T et al. (2015) Analysis of the activity and regulon of the two-component regulatory system composed by Cjj81176_1484 and Cjj81176_1483 of Campylobacter jejuni. J Bacteriol 197:1592-605
Barrero-Tobon, Angelica M; Hendrixson, David R (2014) Flagellar biosynthesis exerts temporal regulation of secretion of specific Campylobacter jejuni colonization and virulence determinants. Mol Microbiol 93:957-74
Kendall, John J; Barrero-Tobon, Angelica M; Hendrixson, David R et al. (2014) Hemerythrins in the microaerophilic bacterium Campylobacter jejuni help protect key iron-sulphur cluster enzymes from oxidative damage. Environ Microbiol 16:1105-21
Abrusci, Patrizia; Vergara-Irigaray, Marta; Johnson, Steven et al. (2013) Architecture of the major component of the type III secretion system export apparatus. Nat Struct Mol Biol 20:99-104

Showing the most recent 10 out of 27 publications