B-168. Differential Function of a Campylobacter jejuni Amino Acid ABC Transporter in Bacterial stress Regulation and Cellular Infection

A. E. Lin1, K. Krastel2, D. G. Cvitkovitch2, E. C. Gaynor1;
1Univ. of British Columbia, Vancouver, BC, CANADA, 2Univ. of Toronto, Toronto, ON, CANADA.

Campylobacter jejuni is an important human pathogen causing severe diarrheal disease. It can also lead to post-infectious complications such as Guillain-Barré Syndrome, the primary cause of acute ascending bilateral paralysis. Despite its prevalence, our current understanding of C. jejuni virulence mechanisms and survival throughout the pathogenesis and transmission processes to cause disease in the human gastrointestinal tract remains limited. Amino acid ATP Binding Cassette (AA-ABC) transporters in C. jejuni have been proposed as important virulence factors necessary for disease etiology. Here, we investigated a novel AA-ABC transporter system, encoded by cj0467-9, by generating targeted deletions of cj0467 (membrane transport component) and cj0469 (ATP-binding component) in C. jejuni 81-176, a highly invasive strain. We then examined if loss of these functional domains in this AA-ABC transporter altered C. jejuni amino acid uptake, caused changes in bacterial stress survival, and affected its pathogenesis during host infection. We found that the AA-ABC transporter mutants exhibited a significant decrease in glutamine uptake compared to wild type. Simultaneous to this observation, the mutants also displayed a surprising increase in resistance to a series of stresses, including oxidative, heat and osmotic shock. Additionally, these mutants exhibited a significant increase in intracellular survival in RAW 264.7 murine macrophage cells and INT407 human epithelial cells. Using annexin-V staining coupled with fluorescence microscopy, we also found that macrophages infected with the cj0467 and cj0469 mutants underwent a significantly lower level of apoptosis than cells infected with wild type bacteria. Furthermore, the mutant-infected macrophages exhibited a remarkable decrease in ERK MAP kinase activation compared to wild type-infected macrophages. Together, these results suggest the function of this AA-ABC transporter in C. jejuni correlates with both bacterial stress response regulation as well as host cell response induction during pathogenesis.