Proteomic analysis of Caenorhabditis elegans against Salmonella Typhi toxic proteins

Abstract Background: Bacterial effector molecules are the crucial infectious agents and are sufficient to cause pathogenesis. In the present study, pathogenesis of Salmonella enteric serovar Typhi (S. Typhi) toxic proteins on the model host Caenorhabditis elegans was investigated by exploring the host regulatory proteins during infection through quantitative proteomics approach. In this regard, the host protein extract was analysed using two-dimensional gel electrophoresis (2D-GE) and differentially regulated proteins were identified using MALDI TOF/TOF/MS analysis. Results: Out of the 150 regulated proteins identified, 95 proteins were appeared to be downregulated while 55 were upregulated. Interaction network for regulated proteins was predicted using STRING tool. Most of the downregulated proteins were found to be involved in muscle contraction, locomotion, energy hydrolysis, lipid synthesis, serine/threonine kinase activity, oxidoreductase activity and protein unfolding and upregulated proteins were found to be involved in oxidative stress pathways. Hence, cellular stress generated by S. Typhi protein extract on the model host was determined using lipid peroxidation, oxidant and antioxidant assays. In addition to that the candidate proteins resulted from the host protein extract analysis were validated by Western blotting and roles of several crucial molecular players were analyzed in vivo using wild type and mutant C. elegans. Conclusions: To the best of our knowledge, this is the first study to report the protein regulation in host C. elegans during S. Typhi toxic proteins exposure which highlights the significance of p38 MAPK and JNK immune pathways. Keywords: Caenorhabditis elegans, Bacterial toxic proteins, 2D-GE, MALDI-TOF-TOF-MS, oxidative stress pathways, Western blotting, immune pathways