Abstract
We have characterized chloroplastic fructose 1,6-bisphosphate aldolase (FBA), one of the glutathionylated proteins previously found in the suspension-cultured cells of Arabidopsis [Plant Cell Physiol. 44:655-660]. The activity of recombinant FBA was upregulated by the conditional transition from pH 7 to 8, and reached the peak level at 10 min after transition. CD spectrometry showed the pH-dependent activation of FBA was accompanied with some structural changes. GSH inhibited the FBA activity at pH 7, but promptly activated it to the peak level at pH 8.
At pH 7, GSSG little affected the FBA activity, while it had a strong activating effect at pH 8. Thioredoxin reduced with DTT inhibited the FBA activity more strongly than DTT alone at between pH 7 and 8, this inhibition being abolished by GSSG. These suggest that the activity of FBA is specifically regulated by glutathione and that the mechanism is not a simple redox regulation.
