Abstract
In the chloroplast stroma, thioredoxin regulates various enzyme acitivities including ATP-synthase, MDH, G6PDH, and the four Calvin cycle enzymes, GAPDH, FBPase, SBPase, and PRK, via the dithiol-disulfide exchange reaction. This regulation system is known as thiol-modulation. Two thioredoxin-isoforms, named Trx-f and Trx-m, function for this redox regulation. On the process of the reduction of the target protein, a reduced form thioredoxin exchanges the disulfide bond and dithiols with the target protein. This disulfide reduction directly affects the enzyme activity of these target proteins.
In the present study, we investigated the thiol-redox system in the thylakoid lumen. HCF164 is a thioredoxin-like protein localized on thylakoids and the catalytic domain containing reactive cysteines of this protein faces the lumen side. We surveyed the possible target proteins for HCF164 in thylakoids, and studied the changes of the redox states of these target proteins. We will discuss the possible role of HCF164 in the lumen.
