The effect of irradiance and redox-modifying reagents on the 52 kDa protein disulfide isomerase of Arabidopsis chloroplasts
2008
Lu, D.P.,University of Hawai, Honolulu (USA). Dept. of Molecular Biosciences and Bioengineering | Christopher, D.A.,University of Hawai, Honolulu (USA). Dept. of Molecular Biosciences and Bioengineering
Immunoblot analysis was used to assess the effects of light and redox-modifying chemicals on the 52 kDa protein disulfide isomerase (PDI) from chloroplasts of Arabidopsis thaliana. A monoclonal antiserum was used that preferentially cross-reacts with the 52 kDa relative to the 65 kDa isoform of PDI. The PDI-52 was most abundant in leaves, flowers, stems and seeds, but was undetected in roots. PDI-52 formed a protein complex (approx. 220 kDa) on blue native gels, indicating that it associates with either itself or other proteins in chloroplasts. Light decreased the levels of PDI-52 by 80%, relative to the control protein (the CF1 subunit of chloroplast ATP synthase). Treatment with dithiothreitol decreased the content of the 52 kDa protein by half. In contrast, when the reduction of plastoquinone is blocked by DCMU, or when the plants are treated with phosphate, PDI-52 contents increased by 1.5 to 2-fold relative to CF1. The effect of the chemical treatments coincided with the effect of the light/dark cycle and implied that light decreased PDI-52 protein content by way of the cellular redox environment.
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