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Differential phosphorylation of thylakoid proteins in mesophyll and bundle sheath chloroplasts from maize plants grown under low or high light
Author(s) -
Fristedt Rikard,
Wasilewska Wioleta,
Romanowska Elzbieta,
Vener Alexander V.
Publication year - 2012
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.201200196
Subject(s) - thylakoid , phosphorylation , photosystem ii , chloroplast , protein phosphorylation , biochemistry , biology , photosystem i , biophysics , photosystem , membrane , peptide , photosynthesis , chemistry , protein kinase a , gene
In C 4 plants, such as maize, the photosynthetic apparatus is partitioned over two cell types called mesophyll ( M ) and bundle sheath ( BS ), which have different structure and specialization of the photosynthetic thylakoid membranes. We characterized protein phosphorylation in thylakoids of the two cell types from maize grown under either low or high light. Western blotting with phosphothreonine antibodies and P ro Q phosphostaining detected light‐dependent changes in the protein phosphorylation patterns. LC‐MS/MS with alternating CID and electron transfer dissociation sequencing of peptide ions mapped 15 protein phosphorylation sites. Phosphorylated D 2, CP 29, CP 26, L hcb2 proteins, and ATP synthase were found only in M membranes. A previously unknown phosphorylation site was mapped in phosphoenolpyruvate carboxykinase from the BS cells. Phosphorylation stoichiometry was calculated from the ratios of normalized ion currents for phosphorylated to nonphosphorylated peptide pairs from the D 1, D 2, CP 43, and P bs H proteins of photosystem II ( PS II). Every PS II in M thylakoids contained on average 1.5 ± 0.1 or 2.3 ± 0.2 phosphoryl groups in plants grown under either low or high light, while in BS membranes the corresponding numbers were 0.25 ± 0.1 or 0.7 ± 0.2, respectively. It is suggested that the phosphorylation level, as well as turnover of PS II depend on the structure of thylakoids.