Momoli, Marisa M , Van Sluys, Marie-Anne .
Distinctive antioxidant profiles: toward the biological role of the Arabidopsis thi1 in organellar genome stability.
Arabidopsis thi1 gene is involved in thiamine biosynthesis, more specifically, in the thiazole ring. Recently, its structure was resolved with an unexpected intermediate identified, namely 2-carboxylate-4-methyl-5-Î²-(ethyl adenosine 5`-diphosphate) thiazole (Godoy et al, 2006; JBC, 281:30957). However, the gene was first described as having a potential role in organellar genome stability due to bacteria and yeast complementation experiments. While an essential cofactor for several carbon mobilization enzymes in chloroplast, mitochondria and cytoplasm, TPP is associated to essential enzymes of the glycolysis, carbon fixation and fermentation pathways. Impairment of any of these pathways would generate reactive oxygen species (ROS). In this work, a comparative study was carried to evaluate the antioxidant response between thi1 wild-type (Ler) and mutant (tz-201) lines under hypoxia growth condition. Ler and tz-201 plants grown in media supplied with free thiamine were analyzed for H2O2, ascorbate (ASC) and glutathione (GSH) contents, and superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase and glutathione peroxidase (GPX) activities. No differences in activity were detected for any of the enzymes tested between Ler and tz-201. However, in the wild-type background an increase in H2O2 content was observed while the mutant line content remained constant. On the other hand, ASC and GSH decreased in Ler whereas in tz-201 an increase was observed. The results presented support tz-201 mutant plants respond differently to the environment conditions even with thiamine supplementation supporting that the tolerance observed may be related to a specific function of THI1 protein.
Log in to add this item to your schedule
1 - Universidade de São Paulo, Departamento de Botânica, Rua do Matão, 277 Sala 153, São Paulo, São Paulo, 05422-970, Brasil
2 - Universidade de São Paulo, Departamento de Botânica
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM