Oxidative modification of proteins in Arabidopsis thaliana wild type and KO-CAT2 knock-out mutant upon heat stress
Aim. Denaturation of proteins and increased generation of reactive oxygen species (ROS) result in plant cell damage upon heat stress. The aim of the study was to elucidate the presumptive protecting role of catalase isoform CAT2 of Arabidopsis thaliana upon increased temperatures. Methods. Leaves of wild type and КО-Cat2 knock-out mutant plants were subjected to heat treatment. Development of heat stress reaction was monitored comparing the intensities of protein carbonylation induced by ROS. Results. It was found that the loss of CAT2 isoform in knock-out mutant causes chronic oxidative stress even in plants cultivated upon optimal grow conditions. Especially, enhanced carbonylation of proteins in intact leaves of mutant plants compared to wild type was demonstrated. The antioxidative defence mechanisms, which are activated in response to the chronic oxidative stress appear to be effective in limiting of lipid peroxidation, but not effective in preventing of protein carbonylation. The constitutive activation of defence mechanisms provides short-term (1 h) protection of the mutant plants upon heat stress. However, upon prolonged severe heat treatment (44 °C, 4 h) the defence mechanisms in mutant plants undergo preferential depletion resulting in enhanced carbonylation of proteins. Conclusions. CAT2 is involved in plant cell protection against thermooxidative stress and appears to be especially important for limiting of protein carbonylation.
Keywords: Arabidopsis thaliana, heat stress, carbonyl groups of proteins, knock-out mutants.