UBIQUITIN-PROTEASOME SYSTEM AND CELLULAR CYCLE PROTEINS IN WHEAT UNDER COPPER STRESS

PENA, LILIANA B.; AZPILICUETA, CLAUDIA E.; PASQUINI, LAURA A.; TOMARO, MARÍA L.; GALLEGO, SUSANA M.

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Ub-proteasome system is responsible for the degradation of proteins in cytoplasm and nucleus, controlling the regulatory short-life proteins that affect processes such as cellular proliferation. The aim of the present work was to evaluate the effect of copper on Ub-proteasome system and on proteins related to cellular cycle. Seeds of Triticum aestivum L. were floated for 48 h on distillated water (control) or adding with 1, 10 y 100 µM CuCl2. The highest Cu concentration used inhibited the germination. Growth was evaluated measuring the length of the primary root. While 1 µM Cu induced the growth (15%), 10 µM Cu inhibited it (54%), effect knew as hormesis. Membrane permeability was unchanged with 1 and 10 µM Cu treatments. Total oxidized proteins were increased with treatments, but total soluble and Ub-proteins contents were unaltered respect to control. In Cu treatments, 20S proteasome protein abundance was similar to control. Although cyclin D protein abundance in treated seedlings was similar to control, with 10 µM Cu decreased Ub-cyclin (30%) and increased oxidized-cyclin level (117%) with respect to control values. CDKD2 protein was unaffected by Cu. In conclusion, Cu did not show effect on the proteasome system but produced oxidation of specific proteins involved in the cellular cycle that could be responsible of growth inhibition observed in the treated seedlings.