Ducret A, Sidler W, Wehrli E, Frank G, Zuber H
Institute for Molecular Biology and Biophysics, Federal Institute of Technology, Zürich, Switzerland.
Eur J Biochem. 1996 Mar 15;236(3):1010-24. doi: 10.1111/j.1432-1033.1996.01010.x.
In this work we present the characterization of a hemidiscoidal phycobilisome type of the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. The phycobilisome of this organism contains allophycocyanin, phycocyanin and phycoerythrocyanin, similar to the closely related thermophilic cyanobacterium Mastigocladus laminosus. Intact phycobilisomes exhibit an absorption maximum at 619 nm and two fluorescence maxima at 664 nm and 680 nm, corroborating the presence of a complete energy pathyway along the antenna. Upon dissociation, the phycobiliproteins were released from the phycobilisome. One phycoerythrocyanin, one phycocyanin and three allophycocyanin complexes were isolated by ion-exchange chromatography and characterized by absorption and fluorescence spectroscopy and by SDS/PAGE. The amino-terminal sequences of the polypeptides belonging to the phycoerythrocyanin and phycocyanin families were identical with the derived sequences of their corresponding genes. Partial amino-terminal sequences of the polypeptides belonging to the allophycocyanin family are presented here. Our results show that the phycobiliproteins and linker polypeptides from Anabaena sp. PCC 7120 are similar to the phycobilisome components characterized in other cyanobacteria. The phycobilisome of Anabaena sp. PCC 7120 was extensively analyzed by electron microscopy. It differs from the common hemidiscoidal tricylindrical, six-rod phycobilisome type by a core domain consisting of five core cylinders surrounded by up to eight rods radiating in a hemidiscoidal manner. One rod is linked to each basal core cylinder, whereas the remaining core cylinders bind two rods each. On the basis of the data presented in this work, a revised model for the hemidiscoidal pentacylindrical phycobilisome of Anabaena sp. PCC 7120, M. laminosus and Anabaena variabilis is proposed. This model accounts more accurately for the 'grape' pattern typically exhibited by these phycobilisomes in electron micrographs.
在本研究中，我们描述了形成异形胞的蓝藻鱼腥藻Anabaena sp. PCC 7120中的一种半盘状藻胆体的特征。该生物体的藻胆体含有别藻蓝蛋白、藻蓝蛋白和藻红胆素蛋白，这与密切相关的嗜热蓝藻层理鞭枝藻Mastigocladus laminosus相似。完整的藻胆体在619 nm处有一个吸收峰，在664 nm和680 nm处有两个荧光峰，证实了沿天线存在完整的能量传递途径。解离后，藻胆蛋白从藻胆体中释放出来。通过离子交换色谱法分离出一种藻红胆素蛋白、一种藻蓝蛋白和三种别藻蓝蛋白复合物，并通过吸收光谱、荧光光谱和SDS/PAGE进行了表征。属于藻红胆素蛋白和藻蓝蛋白家族的多肽的氨基末端序列与其相应基因的推导序列相同。本文给出了属于别藻蓝蛋白家族的多肽的部分氨基末端序列。我们的结果表明，来自鱼腥藻Anabaena sp. PCC 7120的藻胆蛋白和连接多肽与其他蓝藻中表征的藻胆体成分相似。通过电子显微镜对鱼腥藻Anabaena sp. PCC 7120的藻胆体进行了广泛分析。它与常见的半盘状三圆柱形、六杆藻胆体类型不同，其核心结构域由五个核心圆柱体组成，周围最多有八个以半盘状方式辐射的杆。一根杆与每个基部核心圆柱体相连，而其余的核心圆柱体各结合两根杆。根据本研究中的数据，提出了鱼腥藻Anabaena sp. PCC 7120、层理鞭枝藻M. laminosus和多变鱼腥藻Anabaena variabilis的半盘状五圆柱形藻胆体的修订模型。该模型更准确地解释了这些藻胆体在电子显微镜照片中典型呈现的“葡萄”模式。
