Oxidative posttranslational modifications (PTM): an alternative in regulating metabolism during abiotic stress in plants

AAE MENDEZ; MP BENAVIDES; LB PENA; CL MATAYOSHI; SM GALLEGO

Santiago del Estero

Conferencia; SAB XLIV; 2015

Oxidative posttranslational modifications (PTM): an alternative in regulating metabolism during abiotic stress in plants1.- Benavides , MP, 2.- Pena , LB, 3.- Méndez , AEA, 4.- Matayoshi , CL, 5.- Gallego , SMSeveral abiotic stress factors are characterized by disturbing the cell redox balance, increasing the level of reactive oxygen species (ROS). Proteins are one of ROS targets owing to their abundance and reactivity to radicals. Amongst the protein oxidative (redox) changes, carbonylation of the molecules represent an irreversible process that leads to loss of protein functionality. Despite protein carbonylation is associated with general and random processes, studies in our laboratory indicate a great degree of selectivity in the protein oxidation process, thus regulating cell metabolism. There are proteins, such as catalase, that respond to metal-induced oxidative stress by regulating the translation of isoforms and thus inducing the synthesis of new subunits less sensitive to oxidation. Furthermore, the intracellular level of oxidized proteins is the product of a balance between the rate of their oxidation and degradation. Abiotic stress can alter plant cell capacity for removing damaged proteins. As part of the proteolytic system, the 20S proteasome is responsible for the proteolysis of the carbonylated proteins. The 20S proteasome activity is regulated through oxidative modification of the proteasome itself. Whereas a moderate 20S protein oxidation increases its activity, a severe oxidative condition decreases it, concomitantly producing oxidized proteins accumulation. Cellular redox status is currently recognized as an important regulator of cell division. Carbonylation of cell cycle proteins could be an alternative molecular mechanism by which ROS regulate cell proliferation. This would rapidly block cell cycle progression and would allow the cellular defense system to be activated during plant abiotic stress.