RbcL | Rubisco large subunit, form I (rabbit)

Immunogold TEM images of cyanobacterial cells from YNP samples.All cells were immunogold labelled by Rabbit anti-RuBisCO (large subunit, form I and II, AS03 037) at a dilution of 1000X. The gold particles are uniformly sized and dark, two examples are marked by red arrows in (A, B, C). (A) The distribution of immunogold particles tagging free RuBisCO in a cell lacking cyanophycin or carboxysomes. SiO2 around the cell is marked by a black arrow, these granules are bigger than gold particles. (B) The absence of immunogold particles in cyanophycin granules indicates the absence of RuBisCO. (C) Immunogold particles tagging RuBisCO in small inclusions suggest the presence of morphologically atypical carboxysomes. These inclusions are rare and are found in the same areas where large cyanophycin granules typically occur. Few gold particles outside the cell in (A, B, C) indicate a low level backgroung. Scale bars: 200 nm in (A, B), and 100 nm in (C).

Quantitative analysis of RbcL.A) Immunoblot analysis of in vitro expressed and affinity purified RbcL protein using a RbcL-specific antibody and a microcystin-specific antibody, respectively. Microcystin was added as indicated. B) Representative Coomassie-stained gel pictures (upper panel) and immunoblot analyses (lower panel) with a RbcL-specific antibody of soluble protein extracts of M. aeruginosa PCC 7806 wild type (left) and the ΔmcyB mutant (right) after high light treatment of 700 µmol photons m−2 s−1 for up to four hours. The irradiation time of the individual samples is indicated. The sample 4′h was irradiated with high light for three hours and subsequently transferred to low light for one hour.

Isolation and characterization of Arabidopsis cgl160 mutants.A. DNA insertion sites in CGL160 gene of Arabidopsis. DNA insertion sites (black triangles) are shown in relation to the CGL160 gene structure. The two cgl160 alleles analyzed in this study are denoted as cgl160-1 and cgl160-2. The CGL160 coding region is indicated by the translational start (ATG). The CGL160 genomic locus contains nine exons but only the first four are shown in the fig (grey boxes), shown are also the first four introns (black thin connecting lines). Before ATG is the promoter region in light gray. The region used for CGL160 specific antibody is shown as antigen. B. Characterization of CGL160 amount in Arabidopsis cgl160-1 mutant from isolated chloroplasts. The CGL160 antibody was used for immunoblotting and 10 μg protein was loaded in each lane. The LHCB1 antibody was used as a loading control. C. Characterization of CGL160 amount in Arabidopsis cgl160-2 mutant from isolated chloroplasts. The CGL160 antibody was used for immunoblotting and 10 μg protein was loaded in each lane. The LHCB1 antibody was used as a loading control.

Isolation and characterization of Arabidopsis cgl160 mutants.A. DNA insertion sites in CGL160 gene of Arabidopsis. DNA insertion sites (black triangles) are shown in relation to the CGL160 gene structure. The two cgl160 alleles analyzed in this study are denoted as cgl160-1 and cgl160-2. The CGL160 coding region is indicated by the translational start (ATG). The CGL160 genomic locus contains nine exons but only the first four are shown in the fig (grey boxes), shown are also the first four introns (black thin connecting lines). Before ATG is the promoter region in light gray. The region used for CGL160 specific antibody is shown as antigen. B. Characterization of CGL160 amount in Arabidopsis cgl160-1 mutant from isolated chloroplasts. The CGL160 antibody was used for immunoblotting and 10 μg protein was loaded in each lane. The LHCB1 antibody was used as a loading control. C. Characterization of CGL160 amount in Arabidopsis cgl160-2 mutant from isolated chloroplasts. The CGL160 antibody was used for immunoblotting and 10 μg protein was loaded in each lane. The LHCB1 antibody was used as a loading control.

CGL160 is a membrane-integral chloroplast protein located in non-appressed thylakoid membranes.A. Subcellular localization of CGL160. Immunoblot analysis performed on initial plant extract, isolated chloroplasts or isolated mitochondria. TOM40 is a marker for the mitochondrion. B. Suborganellar localization determined by immunoblot analysis of chloroplast proteins diagnostic for photosystem I (PsaA), photosystem II (D1), Rubisco, LHCII (LHCB1.2) and CGL160. Protein extracts were separated by SDS-PAGE and probed with specific antibodies directed against PsaA, (PSI reaction center subunit), D1 (PSII reaction center subunits), LHCB1 (outer PSII antenna protein), the large subunit of Rubisco, a soluble protein in the stroma, and CGL160. C. Immunoblot analysis show that CG160 is an integral membrane protein associated with the thylakoid membranes. Isolated thylakoid membranes were washed with 0.4 M NaCl, and the thylakoid membranes and the supernatant were probed by immunoblotting with antibodies against CGL160 and the PSII reaction center protein D1.

Altered protein accumulation and stability of the chloroplast ATP synthase in the cgl160 mutant visualized by immunoblotting.A. Immunoblots with antibodies against essential subunits of the photosynthetic protein complexes of wild-type (Col-4) Arabidopsis and the two cgl160 T-DNA insertion lines grown under long-day and short-day conditions. Isolated thylakoid membranes were used, and equal amounts of chlorophyll were loaded onto the SDS-PAGE gel. For approximate quantification, wild-type samples from long-day plants were diluted to 10%, 25% and 50%, respectively. Accumulation of PSII was probed with antibodies against PsbB and PSBO. Additionally, the PSBS protein involved in NPQ and the minor PSII antenna protein LHCB4 were probed. Accumulation of the cytochrome b6f complex was probed with antibodies against the essential subunits PetA (cytochrome f), PetB (cytochrome b6), and PETC (Rieske protein). Accumulation of PSI was probed with antibodies against the reaction center subunit PsaB and the stromal ridge subunit PsaD. ATP synthase accumulation was probed with antibodies against the CF1 subunits AtpA (CF1α), AtpB (CF1β) and AtpD (CF1δ) and antibodies against the CF0 subunits AtpF (CF0b) and AtpI (CF0a). B. Loading difference estimation for immunoblotting CF1 between wild type and cgl160-1. To obtain similar immunoblotting signal three times more (15 μg protein) was needed for cgl160-1 compared to wild type (5 μg protein). C. Maintenance of CF1 was measured by incubating leaves from wild type and cgl160-1 in solution containing the plastid protein synthesis inhibitor chloramphenicol for the indicated time points. Protein extract was isolated and separated by SDS-PAGE, immunoblotted and probed with specific antibodies against CF1 and LHCB2.1. Three times more protein was loaded from the mutant to obtain equal level of CF1 immunoblotting signal, as specified in B.

Altered protein accumulation and stability of the chloroplast ATP synthase in the cgl160 mutant visualized by immunoblotting.A. Immunoblots with antibodies against essential subunits of the photosynthetic protein complexes of wild-type (Col-4) Arabidopsis and the two cgl160 T-DNA insertion lines grown under long-day and short-day conditions. Isolated thylakoid membranes were used, and equal amounts of chlorophyll were loaded onto the SDS-PAGE gel. For approximate quantification, wild-type samples from long-day plants were diluted to 10%, 25% and 50%, respectively. Accumulation of PSII was probed with antibodies against PsbB and PSBO. Additionally, the PSBS protein involved in NPQ and the minor PSII antenna protein LHCB4 were probed. Accumulation of the cytochrome b6f complex was probed with antibodies against the essential subunits PetA (cytochrome f), PetB (cytochrome b6), and PETC (Rieske protein). Accumulation of PSI was probed with antibodies against the reaction center subunit PsaB and the stromal ridge subunit PsaD. ATP synthase accumulation was probed with antibodies against the CF1 subunits AtpA (CF1α), AtpB (CF1β) and AtpD (CF1δ) and antibodies against the CF0 subunits AtpF (CF0b) and AtpI (CF0a). B. Loading difference estimation for immunoblotting CF1 between wild type and cgl160-1. To obtain similar immunoblotting signal three times more (15 μg protein) was needed for cgl160-1 compared to wild type (5 μg protein). C. Maintenance of CF1 was measured by incubating leaves from wild type and cgl160-1 in solution containing the plastid protein synthesis inhibitor chloramphenicol for the indicated time points. Protein extract was isolated and separated by SDS-PAGE, immunoblotted and probed with specific antibodies against CF1 and LHCB2.1. Three times more protein was loaded from the mutant to obtain equal level of CF1 immunoblotting signal, as specified in B.

Changes of PSII and PSI antenna and core protein levels. Proteins from control and Tl-treated white mustard leaves were separated by SDS-PAGE followed by immunodetection with antibodies against Lhcb1, Lhcb2, Lhca1 (antenna proteins) and D1, D2, CP43, PsbO, PsaA (core proteins). Samples were loaded on the equal amount of chlorophyll (0.25 μg). Description of samples abbreviation as given in the legend to Fig. 3

Immunological analyses of the relative amounts of photosynthesis-associated proteins during senescence of primary leaves from wild-type (WT) and RNAi-W1-7 plants grown at high irradiance. Samples were prepared from wild-type plants grown for 10, 14, 21, 26, 29, and 31 das, as well as from RNAi-W1-7 plants grown for 10, 14, 21, 24, 29, 31, 34, and 36 das. The analysis was done with two biological replicates. WHIRLY1, photosynthesis-related proteins, and Cu/ZnSOD were detected by specific antibodies.

Perturbation of the RdDM pathway does not significantly affect chlorophyll biosynthesis. (a) Determination of total chlorophyll (Chl a + b) contents of 4-day-old seedlings grown under LD conditions. Chlorophyll was acetone-extracted and measured spectrophotometrically, and concentrations were determined as described (see “Methods”). Data are shown as mean values ± SD from 6 different plant pools. Each pool contained more than 100 seedlings. Significant differences (t-test; p < 0.05) with respect to Col-0 are indicated by asterisks. (b) Graph displaying the Chl a/b ratio of chlorophylls extracted in (a). (c) Immunoblot analysis of representative enzymes involved in chlorophyll biosynthesis (FLU and GBP) and the light-harvesting chlorophyll a/b binding protein Lhcb1. Total protein extracts from 4-day-old seedlings obtained from the wild-type (Col-0) and representative (de)methylation mutants were fractionated by SDS-PAGE, and blots were probed with antibodies raised against the individual proteins. Increasing levels of wild-type proteins were loaded in the lanes marked 0.25 WT, 0.5 WT and WT. The relative loading amounts of each sample were visualized by staining the blot with Ponceau S. FLU, FLUORESCENT IN BLUE LIGHT; GBP, glutamyl-tRNA reductase-binding protein. The figure was assembled from different blots (delineated by a black rectangle) and full-length blots are presented in Supplementary Fig. S6.

Photomorphogenesis is not significantly affected in ros1, nrpd1, nrpe1, rdr2 or ago4 mutant seedlings. (a) Phenotypes (upper panel) and the corresponding maximum quantum yields of PSII (Fv/Fm) (lower panel) of 4-day-old etiolated seedlings. Fv/Fm was measured with an imaging Chl fluorometer (Imaging PAM). Scale bar = 1 cm. (b) Phenotypes (upper panel) and corresponding Fv/Fm values (lower panel) of 3-day-old etiolated seedlings which had been exposed to continuous light for 24 h. (c) Immunoblot analysis of the PSII core proteins (D1 and D2), Lhcb1 and FLU during greening of etiolated seedlings. WT seedlings were grown for 3 days in the dark and exposed to light for between 0 and 48 h, as indicated. Extracted total proteins were normalized with respect to fresh weight and fractionated by SDS-PAGE. Blots were then probed with antibodies raised against the individual proteins. Total proteins from 5-day-old WT seedlings grown under continuous light (LL) and LD conditions (LD) were used as positive controls. The total protein accumulation of each sample was visualized by staining the gel with Coomassie Blue R250 (C.B.). The figure was assembled from different blots (delineated by a black rectangle) and full-length blots are presented in Supplementary Fig. S7. (d) Immunoblot analysis of representative photosynthesis proteins of 3-day-old etiolated mutant seedlings which had been exposed to continuous light for 24 h. Immunoblot analysis was performed as in (c). The figure was assembled from different blots (delineated by a black rectangle) and full-length blots are presented in Supplementary Fig. S8. (e) Real-time PCR analyses of 3-day-old etiolated WT (Col-0) and mutant seedlings that had been exposed to continuous light for 24 h. Real-time PCR was performed with primers specific for the nuclear genes LHCB1.2, LHCB2.1, LHCB6, LHCA5, PSBP-1 and PSBTn, and the plastid genes psaA and atpB. Note that the primers for LHCB2.1 also amplify LHCB2.2 mRNA. Expression values are reported relative to the corresponding transcript levels in the WT and were normalized with respect to the expression level of ACTIN2. Data are shown as mean values ± SD from three different plant pools.

The second, chloroplast growth phase involves greening and is supported by protein accumulation profiles. a Chlorophyll content, quantified in each of three independent biological replicates per sample. Error bars represent standard error of the mean. See Additional file 5: Table S6 for calculations. b, c, d Expression (Z-scores) of pigment biosynthesis and thylakoid biogenesis (b), light reactions (c) and carbon fixation-associated genes (d). e Expression (Z-scores) of chloroplast development-associated transcripts reflecting two stages of plastid development, peaking in the early plastid phase (RCB, ARC5 and TIC40) and, second, chloroplast phase (PSBO2, LHCB1.4 and SBPAse). f Immunoblot analysis of the protein products of the genes displayed in e. In total, 20 μg of protein of samples 1–14 (for PSBO2, LHCB1.4 and SBPAse), 40 μg (for RCB, ARC5 and TIC40) or 10 μg (for Histone H3 as a constitutive control) was separated on denaturing SDS-PAGE gels, transferred to blots and probed with antibodies against the protein indicated. A Coomassie-stained total protein replica gel is also shown. Molecular weights (KDa) are indicated on the left. The results show one typical example from among three independent protein extraction and immunoblot experiments