Photosystem II protein phosphorylation follows four distinctly different regulatory patterns induced by environmental cues

Abstract

Differential redox regulation of thylakoid phosphoproteins was studied in winter rye plants in vivo . The redox state of chloroplasts was modulated by growing plants under different light/temperature conditions and by transient shifts to different light/temperature regimes. Phosphorylation of PSII reaction centre proteins D1 and D2, the chlorophyll a binding protein CP43, the major chlorophyll a / b binding proteins Lhcb1 and Lhcb2 (LHCII) and the minor lightharvesting antenna protein CP29 seem to belong to four distinct regulatory groups. Phosphorylation of D1 and D2 was directly dependent on the reduction state of the plastoquinone pool. CP43 protein phosphorylation generally followed the same pattern, but often remained phosphorylated even in darkness. Phosphorylation of CP29 occurred upon strong reduction of the plastoquinone pool, and was further enhanced by low temperatures. In vitro studies further demonstrated that CP29 phosphorylation is independent of the redox state of both the cytochrome b 6 /f complex and the thiol compounds. Complete phosphorylation of Lhcb1 and 2 proteins, on the contrary, required only modest reduction of the plastoquinone pool, and was subject to inhibition upon increase in the thiol redox state of the stroma. Furthermore, the reversible phosphorylation of Lhcb1 and 2 proteins appeared to be an extremely dynamic process, being rapidly modulated by short-term fluctuations in chloroplast redox conditions.

High Light-Dependent Phosphorylation of Photosystem II Inner Antenna CP29 in Monocots Is STN7 Independent and Enhances Nonphotochemical Quenching

“…Although sharing with STN7 the activation by reduced PQ, CP29 kinase is not inactivated by HL, which is required for CP29 phosphorylation. This strongly suggests involvement of a kinase different from STN7, consistent with the results by Pursiheimo et al (2003; Fig. 2E).…”

Cyclic electron flow around PSI monitored by afterglow luminescence in leaves of maize inbred lines (Zea mays L.): correlation with chilling tolerance

“…This afterglow emission would tend to merge with the B band at a lower temperature when state 2 is induced either by an illumination with white or blue light exciting preferentially PSII or by other treatments, such as anerobiosis (Joe¨t et al 2002). Phosphorylation of PSII antenna and centre proteins is a complex phenomenon following four different regulatory patterns induced by environmental cues (Pursiheimo et al 2003) and some of them play a role in the state transition, hence in the afterglow emission. Phosphorylation of LHCII appears very flexible, whilst that of CP29 is induced only by harsher cold treatments (Bergantino et al 1995;Mauro et al 1997).…”

Quality Control of Photosystem II

“…However, it was shown previously that CP43 is first dephosphorylated and is detached from the PS II complex to ensure removal of the photodamaged D1 protein (38). Phosphorylation and dephosphorylation of the PS II core proteins appear to be catalyzed by kinases and phosphatases that are different from those working in phosphorylation and dephosphorylation of LHCII (39,40). Distribution of phosphatase around PS II and regulation of the phosphatase activity should affect dephosphorylation rates of the D1 protein.…”