Table I.
Phosphorylation of LHCII proteins in vivo and the effect of thiol oxidant on the restoration of LHCII protein phosporylation in thylakoid membranes isolated from high-light-illuminated leaves
Plant leaves were illuminated at low light (LL) or at high light (HL) as described in “Materials and Methods,” and the phosphorylation level of LHCII proteins in isolated thylakoids was analyzed by immunoblotting. Subsequently, thylakoids isolated from the LL-treated and HL-treated leaves were rephosphorylated in vitro in the absence (−DTTox) or presence (+DTTox) of 2 mm thiol oxidant. Phosphoproteins were detected by immunoblotting with phospho-Thr antibody, and the immunoblots were quantified by scanning. Results are presented as a percentage of the phosphorylation level of LHCII proteins in LL-illuminated leaves in vivo. Results are means of three independent experiments ± se. n.d., Not determined.
| Species | In Vivo Phosphorylation
|
In Vitro Assay in Light
|
||||
|---|---|---|---|---|---|---|
| LL Thylakoids
|
HL Thylakoids
|
|||||
| LL | HL | −DTTox | +DTTox | −DTTox | +DTTox | |
| % | ||||||
| Spinach | 100 | 2 ± 2 | 102 ± 5 | 115 ± 2 | 27 ± 7 | 58 ± 10 |
| Pumpkin | 100 | 9 ± 3 | 98 ± 7 | n.d. | 91 ± 8 | 91 ± 3 |