Abstract
To avoid photoinhibition, an efficient degradation of D1 protein in the repair cycle of photosystem II is important. FtsH, an ATP-dependent metalloprotease in thylakoid membranes, is believed to predominantly act in this process. We attempt to demonstrate D1 degradation in vivo using Arabidopsis mutants. Despite the availability of the FtsH2 mutant var2, these leaves show variegation and are not good materials for an in vivo biochemical study. To overcome this problem, we incorporated another mutant fug1 that recovers leaf variegation in var2. Under various light conditions, the ability to degrade D1 in the presence of lincomycin was assayed in fug1 and fug1 var2 leaves using immuno-blot against anti-D1 antibodies. These assays showed that the D1 degradation was significantly attenuated in fug1 var2compared with fug1 irrespective of high and low light conditions. These results suggested that FtsH is required for in vivo degradation of the D1 protein.
