Pena Liliana B, Pasquini Laura A, Tomaro María L, Gallego Susana M
Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires (C1113AAC), Argentina.
Phytochemistry. 2007 Apr;68(8):1139-46. doi: 10.1016/j.phytochem.2007.02.022. Epub 2007 Mar 30.
In order to examine the possible involvement of the 20S proteasome in degradation of oxidized proteins, the effects of different cadmium concentrations on its activities, protein abundance and oxidation level were studied using maize (Zea mays L.) leaf segments. The accumulation of carbonylated and ubiquitinated proteins was also investigated. Treatment with 50 microM CdCl(2) increased both trypsin- and PGPH-like activities of the 20S proteasome. The incremental changes in 20S proteasome activities were probably caused by an increased level of 20S proteasome oxidation, with this being responsible for degradation of the oxidized proteins. When leaf segments were treated with 100 microM CdCl(2), the chymotrysin- and trypsin-like activities of the 20S proteasome also decreased, with a concomitant increase in accumulation of carbonylated and ubiquitinated proteins. With both Cd(2+) concentrations, the abundance of the 20S proteasome protein remained similar to the control experiments. These results provide evidence for the involvement of this proteolytic system in cadmium-stressed plants.
为了研究20S蛋白酶体是否可能参与氧化蛋白质的降解，利用玉米（Zea mays L.）叶片切段研究了不同镉浓度对其活性、蛋白质丰度和氧化水平的影响。还研究了羰基化和泛素化蛋白质的积累情况。用50 microM CdCl₂处理可提高20S蛋白酶体的胰蛋白酶样活性和类PGPH活性。20S蛋白酶体活性的增量变化可能是由20S蛋白酶体氧化水平的提高引起的，这导致了氧化蛋白质的降解。当叶片切段用100 microM CdCl₂处理时，20S蛋白酶体的胰凝乳蛋白酶样和胰蛋白酶样活性也降低，同时羰基化和泛素化蛋白质的积累增加。在两种镉离子浓度下，20S蛋白酶体蛋白的丰度与对照实验相似。这些结果为该蛋白水解系统参与镉胁迫植物提供了证据。
