Abstract
Photosynthetic CO2 fixation takes place through the Calvin cycle in the stroma, and its activity is redox-regulated through the thioredoxin-ferredoxin system. We previously reported that glutathione is involved in the regulation of photosynthesis, and that, among isozymes of chloroplastic fructose-1,6-bisphosphate aldolase (FBA), one isozyme (FBA1) undergoes glutathionylation. It has been known that chloroplastic FBA tetramer catalyzes the two reactions in the Calvin cycle, but it remains unknown how the isozymes participate in the regulation of the Calvin cycle. Arabidopsis plants have three chloroplastic FBA isozymes, FBA1 (At2g01140), FBA2 (At2g21330) and FBA3 (At4g38970). Based on FBA sequences from various plants, those isozymes proved to be classified into two group, FBA1 and FBA2/3 groups. Analysis of FBA complex from Arabidopsis plants revealed that FBA1 was incorporated into the tetramer of FBA2 and FBA3. We will discuss the function of FBA1 in the FBA hetero tetramer.
