AtpC | Gamma subunit of ATP synthase (chloroplastic)

Double mutant maintains thylakoid protein phosphorylation and state transitions after high light. (A) Total protein extracts of wild type (WT), abc1k1.1, -2, abc1k3.1, -2, and abc1k1/abc1k3.1, -2 light-exposed leaves were separated by SDS PAGE, transferred on nitrocellulose membrane and decorated with anti-phosphothreonine antibody. The main thylakoid phospho-proteins are indicated on the right according to their size. Core photosystem II proteins D1 (PsbA) and D2 (PsbD) are indicated together due their poor resolution. (B) The accumulation of the principal photosynthetic complexes was assessed using antibodies against specific subunits of each complex: anti-Lhcb2 for the major LHCII, anti-D1 (PsbA) for PSII, anti-PetC for cytochrome b6f, anti-PsaD and anti-PsaC for PSI, and anti-AtpC for ATP synthase. Actin signal is shown as a loading control. (C) Fluorescence quenching related to the state transitions (qT) of wild type (WT), abc1k1.1, -2, abc1k3.1, -2, and abc1k1/abc1k3.1, -2 under moderate light (120 ?mol of photons m–2 s–1) (ML) and after 3 h of high light (500 ?mol of photons m–2 s–1) (HL). qT was calculated from the maximal chlorophyll fluorescence measured after 10 min exposure to red light (660 nm) supplemented with far-red illumination (720 nm) “State 1” (FMST1) or to pure red light “State 2” (FMST2). Quenching related to state transition was calculated as qT = (FMST1 – FMST2)/FM. Each value represents the average of a pot containing 2–3 plants. Superscript letters are used to indicate statistically different groups (p < 0.05) by paired Student’s t-test.

Accumulation dynamics of photosynthesis-related proteins during de-etiolation.Three-day-old etiolated seedlings of Arabidopsis thaliana were illuminated for 0 hr (T0), 4 hr (T4), 8 hr (T8), 12 hr (T12), 24 hr (T24), 48 hr (T48), 72 hr (T72), and 96 hr (T96) under white light (40 µmol/m2/s). (A) Proteins were separated by SDS-PAGE and transferred onto nitrocellulose membrane and immunodetected with antibodies against PsbA, PsbD, PsbO, PetC, PsaD, PsaC, Lhcb2, AtpC, ELIP, POR, phyA, HY5, and ACTIN proteins. (B–C) Quantification of PsbA, PetC, and PsaC during de-etiolation. Heatmap (B) was generated after normalization of the amount of each protein relative to the last time point (T96). Graph (C) corresponds to the absolute quantification of proteins at T96. Error bars indicate ± SD (n = 3). Quantification of photosystem-related proteins during de-etiolation is detailed in Figure 6—figure supplement 1.Figure 6—source data 1.Quantitative data for immunoblot analysis.Quantitative data for immunoblot analysis.Quantification of photosynthesis-related proteins.(A) Immunodetection of PsbA, PetC, and PsaC during de-etiolation. Dilutions were used for the later time points to avoid saturation of the signal. (B) Different bands were detected by Amersham Imager program and quantified by Image QuantTL (Amersham). (C) Calibration curves were created using recombinant proteins (Agrisera). Calibration curve composition: PsbA 10 ng (A; lane a), 5 ng (b), 2.5 ng (c), and 1.25 ng (d); PetC 10 ng (e), 5 ng (f), 2.5 ng (g), and 1.25 ng (h); PsaC 3 ng (i), 1.5 ng (l), 0.75 ng (m), and 0.325 ng (n). Data indicate mean ± SD (n = 3–4). Raw data and calculations are shown in Figure 6—source data 1.