Proteomic analysis of Caenorhabditis elegans against S. Typhi toxic proteins

Background & Aims Bacterial effector molecules are the crucial infectious agents and are sufficient to cause pathogenesis. In the present study, pathogenesis of S. Typhi toxic proteins on the model host Caenorhabditis elegans was investigated by exploring the host regulatory proteins during infection through quantitative proteomics approach. Methods In this regard, the host proteome was analysed using two-dimensional gel electrophoresis (2D-GE) and differentially regulated proteins were identified using MALDI TOF/TOF/MS analysis. 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. Results 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 proteome on the model host was determined using lipid peroxidation, oxidant and antioxidant assays. In addition to that the candidate proteins resulted from the host proteome 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. These results may provide new clues for future therapeutic approaches for curing bacterial toxin protein-mediated infections in a host system. Summary We have precipitated the toxin proteins of S. Typhi. To gain insight into the worm’s response to ingestion of toxin, a proteomic analysis was performed to monitor the changes in protein regulation. 150 differential regulated proteins were identified, amongst 95 and 55 proteins were found to be downregulated and upregulated, respectively. This is the first study that reported the global proteome changes in C. elegans against toxin. Our findings suggested involvement of several regulatory proteins that appear to play a role in various molecular functions in combating toxin-mediated microbial pathogenicity and/or host C. elegans immunity modulation. A proteomics approach using C. elegans can facilitate the understanding of how toxin can lead to intoxication, which pave a way for delineating how higher eukaryotes could evolve defenses to protect against bacterial toxin. Toxin infection nematode showed increased accumulation of proteins that respond to oxidative –stress, lipid metabolism, embryonic development, immune and inflammatory processes. * 2D-GE : Two Dimensional Differential Gel Electrophoresis, DAF-21 : abnormal Dauer Formation (protein), JNK : C-Jun N-terminal Kinase, MAPK : Mitogen Activated Protein Kinase, MALDI-TOF : Matrix assisted laser desorption ionization-Time of Flight, STRING : Search Tool for the Retrieval of Interacting