Abstract
Green plant photosystem I (PSI) consists of at least 18 different protein subunits. The roles of some of these protein subunits are not well known, in particular those that do not occur in the well characterized PSI complexes from cyanobacteria. We investigated the spectroscopic properties and excited-state dynamics of isolated PSI-200 particles from wild-type and mutant Arabidopsis thaliana plants devoid of the PSI-G, PSI-K, PSI-L, or PSI-N subunit. Pigment analysis and a comparison of the 5 K absorption spectra of the various particles suggests that the PSI-L and PSI-H subunits together bind approximately five chlorophyll a molecules with absorption maxima near 688 and 667 nm, that the PSI-G subunit binds approximately two red-shifted beta-carotene molecules, that PSI-200 particles without PSI-K lack a part of the peripheral antenna, and that the PSI-N subunit does not bind pigments. Measurements of fluorescence decay kinetics at room temperature with picosecond time resolution revealed lifetimes of ~0.6, 5, 15, 50, 120, and 5000 ps in all particles. The 5- and 15-ps phases could, at least in part, be attributed to the excitation equilibration between bulk and red chlorophyll forms, though the 15-ps phase also contains a contribution from trapping by charge separation. The 50- and 120-ps phases predominantly reflect trapping by charge separation. We suggest that contributions from the core antenna dominate the 15-ps trapping phase, that those from the peripheral antenna proteins Lhca2 and Lhca3 dominate the 50-ps phase, and that those from Lhca1 and Lhca4 dominate the 120-ps phase. In the PSI-200 particles without PSI-K or PSI-G protein, more excitations are trapped in the 15-ps phase and less in 50- and 120-ps phases, which is in agreement with the notion that these subunits are involved in the interaction between the core and peripheral antenna proteins.
Full Text
The Full Text of this article is available as a PDF (401.5 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bibby T. S., Nield J., Barber J. Iron deficiency induces the formation of an antenna ring around trimeric photosystem I in cyanobacteria. Nature. 2001 Aug 16;412(6848):743–745. doi: 10.1038/35089098. [DOI] [PubMed] [Google Scholar]
- Boekema E. J., Hifney A., Yakushevska A. E., Piotrowski M., Keegstra W., Berry S., Michel K. P., Pistorius E. K., Kruip J. A giant chlorophyll-protein complex induced by iron deficiency in cyanobacteria. Nature. 2001 Aug 16;412(6848):745–748. doi: 10.1038/35089104. [DOI] [PubMed] [Google Scholar]
- Boekema E. J., Jensen P. E., Schlodder E., van Breemen J. F., van Roon H., Scheller H. V., Dekker J. P. Green plant photosystem I binds light-harvesting complex I on one side of the complex. Biochemistry. 2001 Jan 30;40(4):1029–1036. doi: 10.1021/bi0015358. [DOI] [PubMed] [Google Scholar]
- Chitnis Parag R. PHOTOSYSTEM I: Function and Physiology. Annu Rev Plant Physiol Plant Mol Biol. 2001 Jun;52(NaN):593–626. doi: 10.1146/annurev.arplant.52.1.593. [DOI] [PubMed] [Google Scholar]
- Chitnis V. P., Chitnis P. R. PsaL subunit is required for the formation of photosystem I trimers in the cyanobacterium Synechocystis sp. PCC 6803. FEBS Lett. 1993 Dec 27;336(2):330–334. doi: 10.1016/0014-5793(93)80831-e. [DOI] [PubMed] [Google Scholar]
- Croce R., Dorra D., Holzwarth A. R., Jennings R. C. Fluorescence decay and spectral evolution in intact photosystem I of higher plants. Biochemistry. 2000 May 30;39(21):6341–6348. doi: 10.1021/bi992659r. [DOI] [PubMed] [Google Scholar]
- Croce R., Zucchelli G., Garlaschi F. M., Bassi R., Jennings R. C. Excited state equilibration in the photosystem I-light-harvesting I complex: P700 is almost isoenergetic with its antenna. Biochemistry. 1996 Jul 2;35(26):8572–8579. doi: 10.1021/bi960214m. [DOI] [PubMed] [Google Scholar]
- Croce R., Zucchelli G., Garlaschi F. M., Jennings R. C. A thermal broadening study of the antenna chlorophylls in PSI-200, LHCI, and PSI core. Biochemistry. 1998 Dec 15;37(50):17355–17360. doi: 10.1021/bi9813227. [DOI] [PubMed] [Google Scholar]
- Fromme P., Jordan P., Krauss N. Structure of photosystem I. Biochim Biophys Acta. 2001 Oct 30;1507(1-3):5–31. doi: 10.1016/s0005-2728(01)00195-5. [DOI] [PubMed] [Google Scholar]
- Ganeteg U., Strand A, Gustafsson P., Jansson S. The properties of the chlorophyll a/b-binding proteins Lhca2 and Lhca3 studied in vivo using antisense inhibition. Plant Physiol. 2001 Sep;127(1):150–158. doi: 10.1104/pp.127.1.150. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gobets B., van Grondelle R. Energy transfer and trapping in photosystem I. Biochim Biophys Acta. 2001 Oct 30;1507(1-3):80–99. doi: 10.1016/s0005-2728(01)00203-1. [DOI] [PubMed] [Google Scholar]
- Gobets B., van Stokkum I. H., Rögner M., Kruip J., Schlodder E., Karapetyan N. V., Dekker J. P., van Grondelle R. Time-resolved fluorescence emission measurements of photosystem I particles of various cyanobacteria: a unified compartmental model. Biophys J. 2001 Jul;81(1):407–424. doi: 10.1016/S0006-3495(01)75709-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Haldrup A., Jensen P. E., Lunde C., Scheller H. V. Balance of power: a view of the mechanism of photosynthetic state transitions. Trends Plant Sci. 2001 Jul;6(7):301–305. doi: 10.1016/s1360-1385(01)01953-7. [DOI] [PubMed] [Google Scholar]
- Haldrup A., Naver H., Scheller H. V. The interaction between plastocyanin and photosystem I is inefficient in transgenic Arabidopsis plants lacking the PSI-N subunit of photosystem I. Plant J. 1999 Mar;17(6):689–698. doi: 10.1046/j.1365-313x.1999.00419.x. [DOI] [PubMed] [Google Scholar]
- Haldrup A., Simpson D. J., Scheller H. V. Down-regulation of the PSI-F subunit of photosystem I (PSI) in Arabidopsis thaliana. The PSI-F subunit is essential for photoautotrophic growth and contributes to antenna function. J Biol Chem. 2000 Oct 6;275(40):31211–31218. doi: 10.1074/jbc.M002933200. [DOI] [PubMed] [Google Scholar]
- Ihalainen J. A., Gobets B., Sznee K., Brazzoli M., Croce R., Bassi R., van Grondelle R., Korppi-Tommola J. E., Dekker J. P. Evidence for two spectroscopically different dimers of light-harvesting complex I from green plants. Biochemistry. 2000 Jul 25;39(29):8625–8631. doi: 10.1021/bi0007369. [DOI] [PubMed] [Google Scholar]
- Jansson S. The light-harvesting chlorophyll a/b-binding proteins. Biochim Biophys Acta. 1994 Feb 8;1184(1):1–19. doi: 10.1016/0005-2728(94)90148-1. [DOI] [PubMed] [Google Scholar]
- Jensen P. E., Gilpin M., Knoetzel J., Scheller H. V. The PSI-K subunit of photosystem I is involved in the interaction between light-harvesting complex I and the photosystem I reaction center core. J Biol Chem. 2000 Aug 11;275(32):24701–24708. doi: 10.1074/jbc.M000550200. [DOI] [PubMed] [Google Scholar]
- Jensen Poul Erik, Rosgaard Lisa, Knoetzel Jurgen, Scheller Henrik Vibe. Photosystem I activity is increased in the absence of the PSI-G subunit. J Biol Chem. 2001 Nov 13;277(4):2798–2803. doi: 10.1074/jbc.M110448200. [DOI] [PubMed] [Google Scholar]
- Jordan P., Fromme P., Witt H. T., Klukas O., Saenger W., Krauss N. Three-dimensional structure of cyanobacterial photosystem I at 2.5 A resolution. Nature. 2001 Jun 21;411(6840):909–917. doi: 10.1038/35082000. [DOI] [PubMed] [Google Scholar]
- Kjaerulff S., Andersen B., Nielsen V. S., Møller B. L., Okkels J. S. The PSI-K subunit of photosystem I from barley (Hordeum vulgare L.). Evidence for a gene duplication of an ancestral PSI-G/K gene. J Biol Chem. 1993 Sep 5;268(25):18912–18916. [PubMed] [Google Scholar]
- Knoetzel Jürgen, Mant Alexandra, Haldrup Anna, Jensen Poul Erik, Scheller Henrik Vibe. PSI-O, a new 10-kDa subunit of eukaryotic photosystem I. FEBS Lett. 2002 Jan 16;510(3):145–148. doi: 10.1016/s0014-5793(01)03253-7. [DOI] [PubMed] [Google Scholar]
- Lunde C., Jensen P. E., Haldrup A., Knoetzel J., Scheller H. V. The PSI-H subunit of photosystem I is essential for state transitions in plant photosynthesis. Nature. 2000 Nov 30;408(6812):613–615. doi: 10.1038/35046121. [DOI] [PubMed] [Google Scholar]
- Pålsson L. O., Flemming C., Gobets B., van Grondelle R., Dekker J. P., Schlodder E. Energy transfer and charge separation in photosystem I: P700 oxidation upon selective excitation of the long-wavelength antenna chlorophylls of Synechococcus elongatus. Biophys J. 1998 May;74(5):2611–2622. doi: 10.1016/S0006-3495(98)77967-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheller H. V., Jensen P. E., Haldrup A., Lunde C., Knoetzel J. Role of subunits in eukaryotic Photosystem I. Biochim Biophys Acta. 2001 Oct 30;1507(1-3):41–60. doi: 10.1016/s0005-2728(01)00196-7. [DOI] [PubMed] [Google Scholar]
- Soukoulis V., Savikhin S., Xu W., Chitnis P. R., Struve W. S. Electronic spectra of PS I mutants: the peripheral subunits do not bind red chlorophylls in Synechocystis sp. PCC 6803. Biophys J. 1999 May;76(5):2711–2715. doi: 10.1016/S0006-3495(99)77423-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Swiatek M., Kuras R., Sokolenko A., Higgs D., Olive J., Cinque G., Müller B., Eichacker L. A., Stern D. B., Bassi R. The chloroplast gene ycf9 encodes a photosystem II (PSII) core subunit, PsbZ, that participates in PSII supramolecular architecture. Plant Cell. 2001 Jun;13(6):1347–1367. doi: 10.1105/tpc.13.6.1347. [DOI] [PMC free article] [PubMed] [Google Scholar]