Relationship between the Stability of Antenna Chlα-Binding Proteins CP43/47 and the Accumulation of the Extrinsic 30-kDa Protein in PS II inEuglena

摘要

The accumulation of the extrinsic 30-kDa protein of PS II in thylakoid membranes was studied in relation to the assembly of PS II antenna Chl-proteins CP43/47 and light-harvesting Chi a/b-protein (LHC) in greening cells ofEuglena. We showed previously that the 30-kDa protein accumulates in the membrane later than the reaction center-binding Dl protein (Mizobuchi and Yamamoto 1989). In the present study, the rate of accumulation of the apoproteins of LHC and CP43/47 was shown to be similar to that of the Dl protein. By contrast, we found by non-denaturing lithium dodecyl sulfate-polyacrylamide gel electrophoresis that, at the early stages of greening, newly assembled antenna Chi a-binding proteins CP43 and CP47 were more susceptible to detergent than were the other Chl-protein complexes. Prolonged illumination was required for the stabilization of CP43 and CP47, and the time course of the light-dependent formation of stable CP43/47 paralleled that of the accumulation of the extrinsic 30-kDa protein. These results are discussed in terms of the relationship between the stabilization of CP43/47 and the accumulation of the 30-kDa protein in the thylakoid membrane and the roles of these two processes in the assembly of the oxygen-evolving system inEuglenaare examined.