Localization of different photosystems in separate regions of chloroplast membranes

• Jan M. Anderson

  Division of Molecular Plant Biology, 313 Hilgard Hall, University of California, Berkeley, California 94720

• Anastasios Melis

  Division of Molecular Plant Biology, 313 Hilgard Hall, University of California, Berkeley, California 94720

抄録

The stoichiometric amounts and the photoactivity kinetics of photosystem I (PSI) and of the α and β components of photosystem II (PSII α and PSII β ) were compared in spinach chloroplast membrane (thylakoid) fractions derived from appressed and nonappressed regions. Stroma-exposed thylakoid fractions from the nonappressed regions were isolated by differential centrifugation following a mechanical press treatment of the chloroplasts. Thylakoid vesicles derived mainly from the appressed membranes of grana were isolated by the aqueous polymer two-phase partition method. Stroma-exposed thylakoids were found to have a chlorophyll a /chlorophyll b ratio of 6.0 and a PSII β /PSI reaction center ratio of 0.3. Kinetic analysis of system II photoactivity revealed the absence of PSII α from stroma-exposed thylakoids. The photoactivity of system I in stroma-exposed thylakoids showed a single kinetic component identical to that of unfractionated chloroplasts, suggesting that PSI does not receive excitation energy from the PSII-chlorophyll ab light-harvesting complex. Thus, stroma-exposed thylakoids are significantly enriched in both PSI and PSII β . Inside-out vesicles from the appressed membranes of grana-partition regions had a chlorophyll a /chlorophyll b ratio of 2.0 and a PSII/PSI reaction center ratio of 10.0. The photoactivity of system II showed the membranes of the grana-partition regions to be significantly enriched in PSII α . We conclude that PSII α is exclusively located in the membranes of the grana partitions while PSII β and PSI are located in stroma-exposed thylakoids. The low PSI reaction center (P700) content of vesicles derived from grana partitions and the kinetic homogeneity of the PSI complex suggest total exclusion of P700 as a functional component in the membrane of the grana-partition region.

収録刊行物

• Proceedings of the National Academy of Sciences

  Proceedings of the National Academy of Sciences 80 (3), 745-749, 1983-02

  Proceedings of the National Academy of Sciences

キーワード

• Multidisciplinary

詳細情報

• CRID: 1360574095136176000
• NII論文ID: 30016264596
• DOI: 10.1073/pnas.80.3.745
• ISSN: 10916490
• ISSN: 00278424
• Web Site: https://pnas.org/doi/pdf/10.1073/pnas.80.3.745
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