Institute of Botany, University of Münster, Schlossgarten 3, D-48149, Münster, Germany.
Photosynth Res. 1994 Jun;40(3):279-86. doi: 10.1007/BF00034777.
In cyanobacteria, solubilization of thylakoid membranes by detergents yields both monomeric and trimeric Photosystem I (PS I) complexes in variable amounts. We present evidence for the existence of both monomeric and trimeric PS I in cyanobacterial thylakoid membranes with the oligomeric state depending 'in vitro' on the ion concentration. At low salt concentrations (i.e.≤10 mM MgSO4) PS I is mainly extracted as a trimer from these membranes and at high salt concentrations (i.e.≥150 mM MgSO4) nearly exclusively as a monomer, irrespective of the type of salt used (i.e. mono- or bivalent ions) and the temperature (i.e. 4°C or 20°C). Once solubilized, the PS I trimer is stable over a wide range of ion concentrations (i.e. beyond 0.5 M). A model is presented which suggests a monomer-oligomer equilibrium of PS I, but also of PS II and the cyt. b6/f-complex in the cyanobacterial thylakoid membrane. The possible physiological role of this equilibrium in the regulation of state transitions is discussed.
在蓝藻中，通过去污剂溶解类囊体膜可得到不同数量的单体和三聚体 PS I（Photosystem I）复合物。我们提供了在蓝藻类囊体膜中存在单体和三聚体 PS I 的证据，其多聚体状态取决于“体外”离子浓度。在低盐浓度（即≤10 mM MgSO4）下，PS I 主要从这些膜中作为三聚体提取，而在高盐浓度（即≥150 mM MgSO4）下，几乎仅作为单体提取，而与所用盐的类型（即单价或二价离子）和温度（即 4°C 或 20°C）无关。一旦溶解，PS I 三聚体在很宽的离子浓度范围内（即超过 0.5 M）稳定。提出了一个模型，该模型表明 PS I 的单体-寡聚平衡，但也表明 PS II 和细胞色素 b6/f 复合物在蓝藻类囊体膜中存在平衡。讨论了这种平衡在调节状态转变中的可能生理作用。
