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Earlier researches have pointed about the accumulation of peroxynitrite modified proteins and their aggregates in the etiopathogenesis of many age-related neurodegenerative and several autoimmune diseases. Human serum albumin (HSA) is present in abundance in plasma and is susceptible to modification by peroxynitrite. In this study, HSA modified with peroxynitrite (nitroxidized-HSA) formed aggregate besides other gross structural changes. Aggregation or assembly of aberrant proteins is responsible for increase in production of reactive species and is often correlated with toxicity in neurodegenerative diseases. However, lack of literature on the cytotoxicity of aggregated nitroxidized-HSA led us to explore its toxicity using human peripheral blood lymphocytes. Elevated protein carbonyl coupled with decreased protein thiol, and release of antioxidant enzymes and lactate dehydrogenase (LDH) were observed upon incubation of lymphocytes with nitroxidized-HSA. Trypan blue exclusion and MTT assays indicated nitroxidized-HSA induced injury/death of lymphocytes. This may be attributed to the observed reactive oxygen species generation during the interaction of nitroxidized-HSA with lymphocytes. Moreover, the analysis of the cellular morphology by dual staining, fluorescence and confocal microscopy further confirms the cytotoxicity of nitroxidized-HSA. Since various age-related degenerative diseases are characterized by deposition of protein aggregates, the demonstrated toxicity of nitroxidized-HSA may be an important driver in the pathophysiology of neurodegenerative diseases.
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Objective To determine the function of toxic protein VapC in toxin/antitoxin system of Leptospira species and the cytotoxicity to host cells of the toxic protein.Methods Using genomic DNA of pathogenic L.interrogans serogroup Icterohaemorrhagiae serovar Lai strain Lai as the template,several PCRs were performed to amplify entire vapB,vapC and vapBC genes.Subsequently,the prokaryotic expression systems of vapB,vapC and vapBC genes were constructed.Expression of the target recombinant proteins rVapB and rVapC was detected by SDS-PAGE and the expressed rVapB and rVapC were extracted by NiNTA affinity chromatography.Activity of rVapB and rVapC to lyse the DNAs or RNAs from L.interrogans strain Lai and THP-1 cells were then determined.The changes of transcription and expression of vapB and vapC genes of L.interrogans strain Lai before and after infection of THP-1 cells were detected by real-time fluorescent quantitative RT-PCR and Western blot assay.The eukaryotic expression vectors of the vapB and vapC genes were generated for transfection of host cells and CCK-8 agent was used to detect the effect of leptospiral VapB and VapC proteins on activity of host cells.Results The nucleotide and putative amino acid sequences of the cloned vapB and vapC genes were completely identical with the reported corresponding genes.The constructed prokaryotic expression systems could express rVapB and rVapC,respectively.rVapC displayed RNase avtivity but did not lyse DNA.When L.interrogans strain Lai infected THP-1 cells,the transcription and expression of vapB and vapC genes were upregulated and partial VapC protein was secreted from the leptospiral cells.The mass mortality was observed in HEK293 human renal tubular epithelial ceils containing the vapC gene through transfection.Conclusion VapC protein of L.interrogans strain Lai is a RNase and is secreted during infection of host cells with obvious cytotoxicity.
RESUMO
Clostridium spp. is a common food contaminating anaerobic bacteria. Most of the packaged food contamination found to be caused due to Clostridium spp. Study was done on Clostridium spp. isolated from contaminated food and soil samples to characterize their toxic protein by SDS PAGE and to do their molecular characterization with the help of RAPD associated with restriction digestion by EcoRI using a random primer.