| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
Enterohemorrhagic Escherichia coli (EHEC) O157 isolate F2 of food-origin in an outbreak, showed resistant to NaCl osmolarity but the patient isolate related to the outbreak was sensitive to it. The phenotypic difference in stress-resistance was experimentally demonstrated by mice passage with F2, and mice-passaged, NaCl-sensitive isogenic variant of F2 (MP37) decreased culturability on TSA by oxidation, but retained membrane integrity and some portions were recovered by amendment with puruvate under both stressing, so we speculated that mice passage modifies stress responses of F2.
We further performed a proteome-based analysis to characterize (i) the phenotypic changes induced by in vivo passage, and (ii) the oxidation-stress response in EHEC O157 in relation to viability. Comparative analyses of strains F2 and MP37 showed that ribosome- associated proteins were more abundant in F2, while at least nine proteins were more abundant in MP37, suggesting that changes in stress-resistance during mice passage might be regulated through the modification of ribosomal activities.
Under oxidation, F2 enriched proteins responsible for oxidative resistance, while, the non-culturable MP37 cells showed decreased some oxidation-responsive factors, but about 2,400-fold increase in Outer membrane protein W (OmpW). Although oxidation induced enrichment of OmpW in MP37 after loss of culturability, a mutation in omp W gene increased the recovery from the dormancy, suggesting that the overexpression of OmpW might be suicidal for the microorganism.
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