Investigation of the peroxidase activity and chaperone function of LeTpx, ana atypical 2-cys peroxiredoxin from tomato
2007
Toufaily, C.
The aim of this study is to examine the ambiguous multiple functions of a peroxiredoxin Letpx. The tomato LeTpx is an atypical 2-cystein peroxiredoxin that was initially identified as an interacting protein to the glutathione S-transferase/ peroxidase BI-GST/GPx. To this end, a eukaryotic expression of LeTpx was done in different plasmids, as well as the expression of LeTpx derivatives where the conserved cysteines on its active site were substituted by serine and alanine independently. The involvement of LeTpx in the oxidative stress as well its chaperon function were examined. The role of the conserved cysteines in the activity of the enzyme was also checked. A series of growth curves assays, using different yeast strains (BY4741, BY4741�Tsa1 and EGY48) carrying different plasmids, were performed under different temperatures and under diamide drugs. Analysis of proteins aggregation was also done in the aim to investigate the molecular chaperone function. LeTpx showed a dual role where it could act as a peroxidase and as a molecular chaperone. It could vaguely protect against heat in certain conditions and it could complement the role of the TSA1 which is an important peroxiredoxin in yeast. LeTpx, showed a chaperone function as the amount of aggregated protein was dramatically lower in the strains where LeTpx was expressed then in the control strains. The peroxidatic cysteine 51 was shown to be essential for this protein activity. Deletion of the C-terminal cysteine did not disrupt the protein's chaperone activity.
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