PsaN | PSI-N subunit of photosystem I

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.

Estimation of the efficacy of free and membrane-associated lumen isolation. Western blot detection of FKBP16-1, PsbO1/PsbO2 and PsaN in thylakoid membrane and lumen fractions isolated during lumen preparations. 1—total thylakoids; 2—thylakoid membranes after removal of the free lumen fraction; 3—thylakoid membranes after removal of the membrane-associated lumen fraction; 4—free lumen; 5—membrane-associated lumen. Lanes 1–3 contain 10 µg protein, lanes 4–5 contain 30 µg protein. Arrows indicate protein of interest.