STRUCTURE OF CYANOBACTERIAL PHYCOBILISOMES - MODEL
STRUCTURE OF CYANOBACTERIAL PHYCOBILISOMES - MODEL
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DOI：
10.1007/bf00446810
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发表时间：
1979-01-01
影响因子：
2.8
通讯作者：
COHENBAZIRE, G
中科院分区：
文献类型：
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作者：
BRYANT, DA;GUGLIELMI, G;COHENBAZIRE, G
藻胆体是一种水溶性辅助性色素的超分子复合物，是蓝藻（Synechococcus sp.（4株）、lyngbya - plectonma - phormidium群和Calothrix sp.）和红藻的主要捕光触角。在这些生物的类囊体膜表面发现了这些细胞器的规则排列。在本研究中，对几种蓝藻的半盘状藻胆体进行了分离和固定后的细胞薄片和阴性染色检测。它们的基本结构是相同的。分离的藻胆异构体具有由三堆圆盘状亚基组装而成的三角形核。每一叠包含两个光盘，分别是。直径为12nm，直径约为12nm。6-7纳米厚。每个圆盘都可能被分成两半。3-3.5 nm厚。三角形核的两边各辐射出大约三根棒。直径12纳米。每个杆大约由2到6个盘状亚基组成。6纳米厚。这些圆盘大约被分成两半。3nm厚。.apprx.的平均盘数。形成周围棒材的厚度为6nm，在所研究的菌株中有所不同。对于某些染色适应菌株，平均杆长取决于细胞在生长过程中暴露的光的波长。比较了光谱学、聚丙烯酰胺凝胶电泳和电子显微镜对藻胆体的分析。三角形核明显由异藻蓝蛋白组成，周围杆状体含有藻蓝蛋白和藻红蛋白（当存在时）。提出了半盘状藻胆体的详细模型。该模型可以解释藻胆蛋白组装和能量转移的许多方面。
Phycobilisomes, supramolecular complexes of water-soluble accessory pigments, serve as the major light-harvesting antennae in cyanobacteria [Synechococcus sp. (4 strains), Lyngbya-Plectonema-Phormidium group and Calothrix sp.] and red algae. Regular arrays of these organelles are found on the surface of the thylakoid membranes of these organisms. In the present study, the hemi-discoidal phycobilisomes of several species of cyanobacteria were examined [EM] in thin sections of cells and by negative staining after isolation and fixation. Their fundamental structures were the same. Isolated phycobilisomes possessed a triangular core assembled from three stacks of disc-shaped subunits. Each stack contained two discs which were .apprx. 12 nm in diameter and .apprx. 6-7 nm thick. Each of these discs was probably subdivided into halves .apprx. 3-3.5 nm thick. Radiating from each of two sides of the triangular core were three rods .apprx. 12 nm in diameter. Each rod consisted of stacks of 2 to 6 disc-shaped subunits .apprx. 6 nm thick. These discs were subdivided into halves .apprx. 3 nm thick. The average number of discs of .apprx. 6 nm thickness forming the peripheral rods varied among the strains studied. For certain chromatically adapting strains, the average rod length was dependent upon the wavelength of light to which cells were exposed during growth. Analyses of phycobilisomes by spectroscopic techniques, polyacrylamide gel electrophoresis, and EM were compared. The triangular core was apparently composed of allophycocyanin and that the peripheral rods contained phycocyanin and phycoerythrin (when present). A detailed model of the hemi-discoidal phycobilisome is proposed. This model can account for many aspects of phycobiliprotein assembly and energy transfer.