ULTRASTRUCTURAL AND BIOCHEMICAL-CHARACTERIZATION OF A SYNECHOCYSTIS-6803 MUTANT WITH INACTIVATED PSBA GENES
ULTRASTRUCTURAL AND BIOCHEMICAL-CHARACTERIZATION OF A SYNECHOCYSTIS-6803 MUTANT WITH INACTIVATED PSBA GENES
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DOI：
10.1016/0003-9861(92)90526-3
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发表时间：
1992-06-01
影响因子：
3.9
通讯作者：
ANDERSSON, B
中科院分区：
文献类型：
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作者：
NILSSON, F;SIMPSON, DJ;ANDERSSON, B
对构建的缺失三个epsbA基因的聚球藻6803突变体进行了超微结构和生化特性的研究。该D1缺失突变体也缺乏D2蛋白和叶绿素a结合蛋白CP-47。对野生型和突变型进行一般的超微结构比较，没有发现细胞外观有任何重大变化。我们通过冷冻-断裂分析发现，在野生型类囊体中发现的大约60%的内质面颗粒在突变体中缺失。突变体类囊体中原生质面颗粒的相应增加可能代表光系统II(PS II)多肽的亚复合体，这些多肽在没有D1蛋白的情况下积累。PS I/PS II比值与冻裂数据的关联表明，每个PS II冻裂颗粒中只有一个反应中心。荧光测量表明，突变体中的CP-43多肽与叶绿素结合，可能与藻胆体相连。在没有光系统II反应中心异二聚体和CP-47的情况下，激发能可以从藻胆体转移到光系统I。这表明激子向光系统I的转移是由藻胆体末端递质或通过CP-43直接介导的。
A constructedSynechocystis6803 mutant with a deletion of the threepsbA genes was subjected to ultrastructural and biochemical characterization. This D1-depleted mutant also lacks the D2 protein and the chlorophyll a-binding protein CP-47. A general ultrastructural comparison between the wild type and the mutant did not reveal any major changes in cell appearance. We found by freeze-fracture analysis that approximately 60% of the endoplasmic face particles found in the wild-type thylakoids were missing in the mutant. A corresponding increase in protoplasmic face particles in the mutant thylakoids may represent a subcomplex of those photosystem II (PS II) polypeptides which accumulate in the absence of the D1 protein. Correlation of the PS I:PS II ratio with freeze-fracture data indicates that there is only one reaction center in each PS II freeze-fracture particle. Fluorescence measurements show that the CP-43 polypeptide in the mutant binds chlorophyll and that it may be connected to the phycobilisomes. Excitation energy can be transferred from the phycobilisomes to photosystem I in the absence of the photosystem II reaction center heterodimer and CP-47. This suggests that exciton transfer to photosystem I is mediated either directly by a terminal phycobilisome transmitter or via CP-43.