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Very rapid phosphorylation kinetics suggest a unique role for L hcb2 during state transitions in A rabidopsis
Author(s) -
Leoni Claudia,
Pietrzykowska Malgorzata,
Kiss Anett Z.,
Suorsa Marjaana,
Ceci Luigi R.,
Aro EvaMari,
Jansson Stefan
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12297
Subject(s) - dephosphorylation , phosphorylation , photosystem ii , phosphatase , biochemistry , kinetics , protein phosphorylation , biology , biophysics , photosystem , microbiology and biotechnology , chemistry , photosynthesis , protein kinase a , physics , quantum mechanics
Summary Light‐harvesting complex II ( LHCII ) contains three highly homologous chlorophyll‐ a/b ‐binding proteins ( L hcb1, L hcb2 and L hcb3), which can be assembled into both homo‐ and heterotrimers. Lhcb1 and L hcb2 are reversibly phosphorylated by the action of STN 7 kinase and PPH 1/ TAP 38 phosphatase in the so‐called state‐transition process. We have developed antibodies that are specific for the phosphorylated forms of L hcb1 and L hcb2. We found that L hcb2 is more rapidly phosphorylated than Lhcb1: 10 sec of ‘state 2 light’ results in L hcb2 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 L hcb1 and L hcb2 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 L hcb1 and L hcb2 in the regulation of photosynthetic light harvesting.