Botany Department, University of Georgia, Athens, Georgia 30602.
Plant Physiol. 1986 Sep;82(1):114-20. doi: 10.1104/pp.82.1.114.
Photosystem II particles of Chlamydomonas reinhardtii contain three extrinsic polypeptides of 29, 20, and 16 kilodaltons, whose functions are incompletely defined. We prepared a monospecific polyclonal antibody against the 29 kilodalton protein and determined that it also specifically recognizes a protein of approximately 33 kilodaltons in thylakoid membrane fractions of several vascular plants, eukaryotic algae, and a cyanobacterium. The cross-reacting 33 kilodalton protein of pea was removed from inverted thylakoid vesicles by CaCl(2) washes demonstrating the structural relationship between the Chlamydomonas polypeptide and the largest subunit of the water oxidation complex of vascular plants. Functional identity of the Chlamydomonas polypeptide was confirmed by antibody inhibition of O(2) evolution in inverted pea vesicles. In contrast to wild-type cells, only low levels of the 29 kilodalton polypeptide are recovered with purified thylakoid membranes of the mutants examined. However, we show that the mature form of the 29 kilodalton polypeptide accumulates to wild-type levels in whole cell extracts of photosystem II deficient mutants and a water oxidation mutant of Chlamydomonas. Impaired membrane assembly has no effect on the maturation or stability of this component of the multi-subunit water oxidation complex.
集光复合体 II 颗粒含有三种 29、20 和 16 千道尔顿的外在多肽，其功能尚未完全确定。我们制备了一种针对 29 千道尔顿蛋白的单特异性多克隆抗体，并确定它还特异性地识别几种维管束植物、真核藻类和蓝细菌类囊体膜部分的约 33 千道尔顿的蛋白质。豌豆的交叉反应 33 千道尔顿蛋白通过 CaCl(2) 洗涤从反转类囊体泡中去除，证明了 Chlamydomonas 多肽与维管束植物水氧化复合物的最大亚基之间的结构关系。豌豆反转类囊体泡中抗体抑制 O(2) 演化证实了 Chlamydomonas 多肽的功能同一性。与野生型细胞相比，用所研究的突变体纯化的类囊体膜仅回收低水平的 29 千道尔顿多肽。然而，我们表明，在 photosystem II 缺陷突变体和 Chlamydomonas 的水氧化突变体的整个细胞提取物中，29 千道尔顿多肽的成熟形式积累到野生型水平。膜组装受损对多亚基水氧化复合物这一成分的成熟或稳定性没有影响。
