Abstract
Plants reserve nitrogen and sulfur (S) as seed storage proteins (SSPs) for germination of next generation. Composition of SSPs changes according to sulfur availability in soil to maintain nitrogen contents in seeds. To understand the adaptation mechanisms to nutritional stress and find the signal transduction pathway in plant seeds, we examined the difference of protein accumulation patterns in Arabidopsis seeds harvested under S-deficient and control condition by proteome analysis.
Several proteins increased under S-deficient condition. They were identified as modified forms of the 12S SSPs, CRA1 and putative cruciferin. MALDI-TOFMS analyses showed the C-terminal processing did not occurred under S-deficient condition. Other proteins that increased under S deficiency were identified as a precursor of CRA1 and alpha-subunits of CRA1 and putative cruciferin whose isoelectric points were shifted. These results suggested SSPs undergo some different post-translational cleavages and modifications under S-deficient condition.
