PsaB | PSI-B core subunit of photosystem I

Membrane protein complexes of PSII and PSI survive in the 35S:A9 seedlings.(A) Western detection of complexes after the H2O2 treatments. The PSII complexes (top) separated by BN-PAGE were detected using anti-D1 (DE-loop) antibodies at 1/5,000 dilution. The PSI complexes (bottom) were detected using anti-PsaB antibodies at 1/4,000 dilution. PSII symbols: •, and the bracket on top respectively mark the dimeric PSII complex, and the PSII-LHCII super-complexes. The asterisk marks the CVII (CP43-less PSII monomer) complex. PSI symbols: • marks the PSI-LHCI super-complex that co-migrates in our gel system with the dimeric PSII complex; the asterisk marks the PSI monomer. (B) The PSII complexes also withstand drastic dehydration. The thylakoid samples were analyzed immediately (0 h) after the dehydration treatment (DT), and following rehydration for 16 h, DT (16 h). In this case the complexes were detected using anti-D1 (C-terminal) antibodies at 1/15,000 dilution. An additional PSII complex mentioned in the text is indicated: CV (**, PSII monomer).

Photosynthetic properties of ?rpoZ. (A) Light-saturated photosynthetic activity of a 1 ml of culture (OD730 = 1) of CS (white bar) and ?rpoZ (black bar) in standard conditions. Each bar represents an average of three independent biological replicates, and the error bars denote SE. (B) Fluorescence at 77 K was measured using 440-nm light that excites Chl. The data were normalized by dividing with the height of the PSI emission peak at 723 nm. (C) Total proteins were isolated, separated with SDS-PAGE and the amounts of PSI reaction center protein PsaB, PSII core protein CP43 and the phycobilisome proteins allophycocyanin (APC) and phycocyanin (PC) were measured by western blotting. The protein contents of PsaB, CP43, ACP and PC were 99 ± 6%, 97 ± 7, 103 ± 7% and 99 ± 4, respectively, in ?rpoZ of that measured in CS.

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 (CF1?), AtpB (CF1?) and AtpD (CF1?) 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 ?g protein) was needed for cgl160-1 compared to wild type (5 ?g 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.

Immunoblot analysis of photosynthetic complex accumulation in wild-type tobacco and the two ?psaI lines grown under low, intermediate, and high-light conditions. Because the accumulation of most tested proteins was highest under high-light conditions, lanes one to three contain samples diluted to 25%, 50%, and a 100% sample of wild-type tobacco grown under high-light conditions, to allow for semi-quantitative determination of changes in protein abundance. Lanes four and five contain the two transplastomic lines grown at 1000 µE m?2 s?1. Lanes six to eight contain wild-type tobacco and the mutants grown at intermediate light intensities, and lanes nine to eleven contain samples grown at low light intensities. For PSII, the accumulation of the essential subunits PsbB (CP43) and PsbD (D2) and the LHCB1 antenna protein were determined, while for the cytochrome b6f complex, the accumulation of the essential redox-active subunits PetA (cytochrome f), PetB (cytochrome b6), and PETC (Rieske FeS protein) was tested. AtpB was probed as an essential subunit of the chloroplast ATP. For PSI, in addition to the three essential plastome-encoded subunits PsaA, PsaB, and PsaC, the accumulation of the nuclear-encoded subunits PSAD, PSAH, PSAK, PSAL, and PSAN and of the four LHCI proteins (LHCA1, LHCA2, LHCA3, LHCA4) was determined. Finally, we examined the accumulation of Ycf4, the chloroplast-encoded PSI-biogenesis factor encoded in the same operon as PsaI, and the nuclear-encoded assembly factor Y3IP1.

Content of proteins functioning in the photosynthetic electron transfer chain (PETC), cyclic electron flow (CEF), and chlororespiration in WT, ntrc, OE?NTRC, pgr5, and ndho. (a) Representative immunoblots showing the content of D1, PsaB, Cyt f, NdhH, NdhS, PGR5, PGRL1, and PTOX. Appropriate amount of thylakoid extract (based on protein content) was separated with SDS?PAGE and probed with specific antibodies. Equal loading was confirmed by protein staining with Li?Cor Revert Total Protein Stain. (b) Relative content of proteins in mutant lines as percentage of WT. The numbers represent the average protein content ±SE in three to five biological replicates. The quantified values were normalized to the total protein content in the sample determined with Li?Cor Revert Total Protein Stain. Statistically significant differences to WT according to Student's t tests (p < 0.05) are marked with *

Stepwise detachment of photosynthetic protein complexes from the thylakoid membrane of WT, stn7, stn8, stn7stn8, and tap38/pph1. Thylakoid membranes of WT, stn7, stn8, stn7stn8, and tap38/pph1 plants harvested from moderate growth light (GL, 120 ?mol photons m?2 s?1) or after high light illumination (HL, 600 ?mol photons m?2 s?1 for 2 hr) were isolated and solubilized with 0%, 0.25%, 0.5%, 1%, and 2% DIG. Equal volumes of the soluble supernatant (S) and insoluble pellet (P) fractions were loaded and separated in SDS?PAGE followed by immunodetection of (a) proteins D1, PSAB, CYTF, and ATPF representing the protein complexes PSII, PSI, LHCII, Cyt b6f, and ATP synthase, respectively, as well as (b) proteins LHCB1, P?LHCB1, LHCB2, P?LHCB2, and LHCB3, representing the different subunits of the LHCII complexes. The differences in mutants with respect to WT as well as the differences in WT in response to Hl are marked with white boxes. Representative data from three different biological replicates are shown