Evidence for light-dependent and light-independent protein dephosphorylation in chloroplasts.

A number of photosystem II (PSII) associated proteins, including core proteins D1, D2 and CP43, and several proteins of the LHCII complex, are phosphorylated by a thylakoid-bound, redox-regulated kinase(s). We demonstrate here that the compound propyl gallate is an effective inhibitor of LHCII phosphorylation in vivo while having little effect on PSII core protein phosphorylation. Using this inhibitor, we demonstrate that LHCII dephosphorylation is insensitive to light in vivo. Taken together with our previous conclusion (Elich et al., EMBO J. 12 (1993) 4857-4862) that PSII core protein dephosphorylation is light-stimulated, our data suggest the presence of multiple phosphatases responsible for thylakoid protein dephosphorylation in vivo.