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首页> 外文会议>International Congress on Photosynthesis >Analysis of PSI and PSII driven electron transport during steady-state photosynthesis in the cyanobacterium Synechococcus PCC7942
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Analysis of PSI and PSII driven electron transport during steady-state photosynthesis in the cyanobacterium Synechococcus PCC7942

机译：稳态光合作用稳态光合作用稳态光合作用PSI和PSII驱动电子传输分析PCC7942

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The inorganic carbon concentrating mechanism (CCM) of cyanobacteria is supported by the active, inward transport of CO_2 and HCO_3~-.Intracellular concentrations of Ci greater than 1000 times those in the external medium, resultant from the activity of the CCM, ensure that CO_2 fixation is saturated (Badger and Gallagher 1987). The energisation of CO_2 and HCO_3~- transport in cyanobacteria is thought to be dependent upon the flow of electrons from PSII to PSI. It was shown in Synechocystis PCC 6803 that NDH-1 complexes can participate in cyclic electron transport around PSI via the re-reduction of plastoquinone and that these complexes were involved in some way in CO_2 uptake (Mi et al. 1992, Ogawa 1991). This prompted some to speculate that CO_2 uptake was coupled to cyclic electron transport by a 'CA-like'conversion of CO_2 to HCO_3~- mediated by a specialised NDH-1 complex (Kaplan and Reinhold 1999). In the same organism NDH-1 complexes containing NDHD3 or NDHD4 subunits were shown to be necessary for CO_2 transport. A double mutant (NDHD3-/NDHD4-) which had no CO_2 uptake showed normal P700+ oxidation kinetics suggesting that cyclic electron transport might not participate directly in CO_2 uptake (Ohkawa et al. 2000). The present study wasundertaken to provide insight into the nature of photosynthetic electron flux in the cyanobacterium, Synechococcus PCC 7942, under conditions where photosynthesis was driven primarily by CO_2 or HCO_3~- transport to delineate the contributions of linearand cyclic electron flows in the energisation of these Ci fluxes. A novel methodology for the combined measurement of the quantum yields of PSI and PSII and photosynthetic gas exchange is described.
机译：Cyanobacteria的无机碳浓缩机制（CCM）由CI _2和HCO_3〜-.IntroCellular浓度的CI浓度大于1000倍，从CCM的活性中得到的，确保CO_2固定是饱和的（獾和加拉赫1987）。 CO_2和HCO_3〜 - 凝聚胞间菌的动力依赖于从PSII到PSI的电子流动。它在SyneChocystis PCC 6803中显示，NDH-1络合物可以通过再减少塑性醌在PSI周围参与PSI周围的循环电子传输，并且这些配合物在CO_2摄取中以某种方式涉及（MI等人，1992，Ogawa 1991）。这提示一些推测CO_2摄取通过通过专用NDH-1复合物（Kaplan和Reinhold 1999）介导的CO_2至HCO_3〜HCO_3〜HCO_3的循环电子传输。在相同的生物体中，含有NDHD3或NDHD4亚基的NDH-1络合物被认为是CO_2转运所必需的。没有CO_2摄取的双突变体（NDHD3- / NDHD4-）显示正常的P700 +氧化动力学，表明循环电子传输可能不会直接参与CO_2摄取（OHKAWA等人。2000）。本研究尚未在光合作用主要由CO_2或HCO_3〜 - 传输以描绘这些循环电子流量的情况下，提供了对蓝色细菌的光合作用的光合杆菌PCC 7942中的光合作用的性质的洞察CI助焊剂。描述了一种用于组合PSI和PSII和光合气体交换的量子产量的组合测量的新方法。

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