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Abstract

Campylobacter jejuni is a human pathogen that causes severe diarrhea! disease. However, our understanding of C. jejuni virulence mechanisms and survival during disease and transmission remains limited. Amino acid ATP Binding Cassette (AA-ABC) transporters in C. jejuni have been proposed as being important for bacterial physiology and pathogenesis. We have investigated a novel AA-ABC transporter system, encoded by cj0467-9, by generating targeted deletions of cj0467 (membrane transport component) and cj0469 (ATPase component) in C. jejuni 81-176. Analyses described herein have led us to designate these genes paqP and paqQ, respectively [pathogenesis-ssociated glutamine (q) ABC transporter permease () and ATPase (Q)]. We found that loss of either component resulted in amino acid uptake defects, most notably diminished glutamine uptake. Both ΔpaqP and ΔpaqQ mutants also exhibited a surprising but significant increase in short-term intracellular survival in macrophages and epithelial cells. Levels of resistance to a series of environmental and in vivo stresses were examined. Both mutants were hyper-resistant to aerobic and oxidative stress, and while ΔpaqP was also hyper-resistant to heat and osmotic shock, ΔpaqQ was more susceptible than wild-type to the latter two stresses. Annexin-V staining coupled with fluorescence microscopy revealed that macrophages infected with the ΔpaqP and ΔpaqQ mutants underwent a lower level of apoptosis than cells infected with wild-type bacteria. Macrophages infected with the mutant strains exhibited a transient decrease in ERK activation compared to wild type-infected macrophages, potentially explaining the reduced apoptosis phenotype. The ΔpaqP mutant did not exhibit a defect for short or longer term mouse colonization, consistent with its increased stress survival and diminished host cell damage phenotypes. Collectively, these results demonstrate a unique correlation between an AA-ABC transporter with bacterial stress tolerance, intracellular survival, host cell damage, and host signal transduction in response to pathogen infection.