Very rapid phosphorylation kinetics suggest a unique role for Lhcb2 during state transitions in Arabidopsis |
| |
Authors: | Claudia Leoni Malgorzata Pietrzykowska Anett Z. Kiss Marjaana Suorsa Luigi R. Ceci Eva‐Mari Aro Stefan Jansson |
| |
Affiliation: | 1. Ume? Plant Science Centre, Department of Plant Physiology, Ume? University, , 901 87 Ume?, Sweden;2. Department of Biosciences Biotechnologies and Pharmacology Sciences, Bari University, , 70126 Bari, Italy;3. Department of Biochemistry and Food Chemistry, Molecular Plant Biology, University of Turku, , FI‐20014 Turku, Finland;4. Institute of Biomembranes and Bioenergetics, CNR, , 70126 Bari, Italy |
| |
Abstract: | Light‐harvesting complex II (LHCII) contains three highly homologous chlorophyll‐a/b‐binding proteins (Lhcb1, Lhcb2 and Lhcb3), which can be assembled into both homo‐ and heterotrimers. Lhcb1 and Lhcb2 are reversibly phosphorylated by the action of STN7 kinase and PPH1/TAP38 phosphatase in the so‐called state‐transition process. We have developed antibodies that are specific for the phosphorylated forms of Lhcb1 and Lhcb2. We found that Lhcb2 is more rapidly phosphorylated than Lhcb1: 10 sec of ‘state 2 light’ results in Lhcb2 phosphorylation to 30% of the maximum level. Phosphorylated and non‐phosphorylated forms of the proteins showed no difference in electrophoretic mobility and dephosphorylation kinetics did not differ between the two proteins. In state 2, most of the phosphorylated forms of Lhcb1 and Lhcb2 were present in super‐ and mega‐complexes that comprised both photosystem (PS)I and PSII, and the state 2‐specific PSI–LHCII complex was highly enriched in the phosphorylated forms of Lhcb2. Our results imply distinct and specific roles for Lhcb1 and Lhcb2 in the regulation of photosynthetic light harvesting. |
| |
Keywords: | Arabidopsis Lhcb2 LHCII phosphorylation state transitions |
|
|