Phosphatidylglycerol Requirement for the Function of Electron Acceptor Plastoquinone Q_B in the Photosystem II Reaction Center

Citations Over TimeTop 10% of 2002 papers

Abstract

Phosphatidylglycerol (PG), a ubiquitous constituent of thylakoid membranes of chloroplasts and cyanobacteria, is demonstrated to be essential for the functionality of plastoquinone electron acceptor Q(B) in the photosystem II reaction center of oxygenic photosynthesis. Growth of the pgsA mutant cells of Synechocystis sp. PCC6803 that are defective in phosphatidylglycerolphosphate synthase and are incapable of synthesizing PG, in a medium without PG, resulted in a 90% decrease in PG content and a 50% loss of photosynthetic oxygen-evolving activity as reported [Hagio, M., Gombos, Z., Várkonyi, Z., Masamoto, K., Sato, N., Tsuzuki, M., and Wada, H. (2000) Plant Physiol. 124, 795-804]. We have studied each step of the electron transport in photosystem II of the pgsA mutant to clarify the functional site of PG. Accumulation of Q(A)(-) was indicated by the fast rise of chlorophyll fluorescence yield under continuous and flash illumination. Oxidation of Q(A)(-) by Q(B) plastoquinone was shown to become slow, and Q(A)(-) reoxidation required a few seconds when measured by double flash fluorescence measurements. Thermoluminescence measurements further indicated the accumulation of the S(2)Q(A)(-) state but not of the S(2)Q(B)(-) state following the PG deprivation. These results suggest that the function of Q(B) plastoquinone was inactivated by the PG deprivation. We assume that PG is an indispensable component of the photosystem II reaction center complex to maintain the structural integrity of the Q(B)-binding site. These findings provide the first clear identification of a specific functional site of PG in the photosynthetic reaction center.

Related Papers

• → Quantitation of the rapid electron donors to P700, the functional plastoquinone pool, and the ratio of the photosystems in spinach chloroplasts.(1984)184 cited
• → Reaction kinetics of intermediates of the photosynthetic chain between the two photosystems(1972)43 cited
• → Localization of electron transport inhibition in plastoquinone reactions(1982)15 cited
• → Investigating changes in the redox state of Photosystem I at low pH(2015)1 cited
• → Multiparticle Direct Simulation of Photosynthetic Electron Transport Processes(2007)2 cited