20S proteasome and accumulation of oxidized and ubiquitinated proteins in maize leaves subjected to cadmium stress. Phytochemistry

Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires (C1113AAC), Argentina.
Phytochemistry (Impact Factor: 2.55). 04/2007; 68(8):1139-46. DOI: 10.1016/j.phytochem.2007.02.022
Source: PubMed


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.

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Available from: Liliana Beatriz Pena, Jan 06, 2015
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    • "proteins has been observed in plants with inhibited HSP90 and UPS activities ( Nishizawa - Yokoi et al . , 2010 ) . The inhibition of the 26S proteasome , followed by the accumulation of polyubiquitinated proteins , stimulates the expression of heat - inducible genes in the cells of plants and mammals ( Kim et al . , 1999 ; Kurepa et al . , 2008 ; Pena et al . , 2007 ) . We have found that TYLCV infection of tomato plants by itself does not lead to significant changes in the pattern of polyubiquitinated proteins , but reduces the levels of protein Fig . 6 Heat shock protein 90 ( HSP90 ) inactivation enhances the aggregation of Tomato yellow leaf curl virus ( TYLCV ) coat protein ( CP ) ."
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    ABSTRACT: To ensure a successful long-term infection cycle, begomoviruses must restrain their destructive effect on the host cells and prevent drastic plant responses, at least in the early stages of infection. The monopartite begomovirus Tomato yellow leaf curl virus (TYLCV) does not induce a hypersensitive response and cell death upon whitefly-mediated infection of virus-susceptible tomato plants, until diseased tomatoes become senescent. The way begomoviruses evade the plant defenses and interfere with the cell death pathways is still poorly understood. We show here that the chaperone HSP90 and its co-chaperone SGT1 are involved in the establishment of TYLCV infection. Inactivation of HSP90 as well as silencing of the Hsp90 and Sgt1 genes leads to accumulation of damaged ubiquitinated proteins, and to a cell death phenotype. These effects are relieved under TYLCV infection. HSP90-dependent inactivation of 26S proteasome degradation and the transcriptional activation of the heat shock transcription factors HsfA2 and HsfB1 and that of the downstream genes Hsp17, Apx1/2 are suppressed in TYLCV-infected tomatoes. Following suppression of plant stress response, TYLCV can replicate and accumulate in a permissive environment. This article is protected by copyright. All rights reserved.
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    • "Over-production of ROS leads to oxidative damage in proteins manifested by protein carbonylation (Braconi et al., 2011). In fact, an increase in the levels of carbonylated proteins has been observed in maize, pea, alfalfa, cucumber, sunflower, and potato plants treated with cadmium (Romero-Puertas et al., 2002; Pena et al., 2006, 2007; Gonçalves et al., 2009). Some of the oxidized proteins in pea plants were identified as Rubisco and antioxidant enzymes namely glutathione reductase, manganese superoxide dismutase and catalase (Romero-Puertas et al., 2002). "
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    • "tration of the metal . Djebali et al . ( 2008 ) showed a similar behaviour in Solanum lycopersicum roots to that observed in soybean roots with a reduction in carbonyl group content , although increasing in leaves only for the higher Cd concen - trations , as already observed in pea or maize leaves of plants exposed to Cd ( Sandalio et al . 2001 ; Pena et al . 2007 ) . Further - more , an increase was observed in carbonylation in durum wheat roots and leaves after 3 and 7 d of 20 and 30 μm Cd exposure , but no differences were observed with a lower concentration ( Paradiso et al . 2008 ) ."
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