Department of Botany, Arizona State University, 85287-1601, Tempe, AZ, USA.
Photosynth Res. 1994 Jul;41(1):285-94. doi: 10.1007/BF02184169.
The evolutionary position of the heliobacteria, a group of green photosynthetic bacteria with a photosynthetic apparatus functionally resembling Photosystem I of plants and cyanobacteria, has been investigated with respect to the evolutionary relationship to Gram-positive bacteria and cyanobacteria. On the basis of 16S rRNA sequence analysis, the heliobacteria appear to be most closely related to Gram-positive bacteria, but also an evolutionary link to cyanobacteria is evident. Interestingly, a 46-residue domain including the putative sixth membrane-spanning region of the heliobacterial reaction center protein shows rather strong similarity (33% identity and 72% similarity) to a region including the sixth membrane-spanning region of the CP47 protein, a chlorophyll-binding core antenna polypeptide of Photosystem II. The N-terminal half of the heliobacterial reaction center polypeptide shows a moderate sequence similarity (22% identity over 232 residues) with the CP47 protein, which is significantly more than the similarity with the Photosystem I core polypeptides in this region. An evolutionary model for photosynthetic reaction center complexes is discussed, in which an ancestral homodimeric reaction center protein (possibly resembling the heliobacterial reaction center protein) with 11 membrane-spanning regions per polypeptide has diverged to give rise to core of Photosystem I, Photosystem II, and of the photosynthetic apparatus in green, purple, and heliobacteria.
对具有类似于植物和蓝细菌的光合作用装置的光合细菌——噬盐菌，在其与革兰氏阳性菌和蓝细菌的进化关系方面，其进化地位已经过研究。根据 16S rRNA 序列分析，噬盐菌似乎与革兰氏阳性菌最为密切相关，但与蓝细菌也有明显的进化联系。有趣的是，噬盐菌反应中心蛋白的一个包含 46 个残基的假定第六跨膜区的结构域与 CP47 蛋白（光合作用系统 II 的叶绿素结合核心天线多肽）的第六跨膜区显示出相当强的相似性（33%的一致性和 72%的相似性）。噬盐菌反应中心多肽的 N-末端一半与 CP47 蛋白具有中等序列相似性（232 个残基中有 22%的一致性），与该区域的光合作用系统 I 核心多肽相比，其相似性显著更高。讨论了光合反应中心复合物的进化模型，其中一个具有 11 个跨膜区的同源二聚体反应中心蛋白（可能类似于噬盐菌的反应中心蛋白）发生了分歧，产生了光合作用系统 I、光合作用系统 II 的核心，以及绿、紫和噬盐菌的光合装置的核心。
