Valentin K, Zetsche K
Institut für Pflanzenphysiologie, Justus Liebig Universität, Giessen, FRG.
Plant Mol Biol. 1990 Oct;15(4):575-84. doi: 10.1007/BF00017832.
The genes for both subunits of Rubisco (rbcL, rbcS) are located on the plastome of the brown alga Ectocarpus siliculosus (Chromophyta, Phaeophyceae). The organization of these genes in the form of an operon was similar to that found in rhodoplasts, cyanobacteria and the plastids of Cryptomonas phi. Sequence analysis of the complete operon revealed a high degree of homology and great structural similarities to corresponding genes from two red algae. In contrast, sequence homology to Rubisco genes from chloroplasts and cyanobacteria was much lower. This clearly indicated a close phylogenetic relationship between the plastids of Rhodophyta and Chromophyta which seem to have evolved independently from the chloroplasts (polyphyletic origin). Our data suggest that the plastids of Chromophyta and Cryptophyta have originated from endosymbiotic unicellular red algae. Surprisingly, red and brown algal Rubiscos show a significantly higher degree of homology to that from a hydrogen bacterium than to those from cyanobacteria.
核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）两个亚基的基因（rbcL、rbcS）位于褐藻硅藻（Chromophyta，Phaeophyceae）的质体基因组上。这些基因以操纵子的形式组织，与红藻质体、蓝细菌和隐藻phi的质体中发现的情况相似。对完整操纵子的序列分析表明，与两种红藻的相应基因具有高度同源性和很大的结构相似性。相比之下，与叶绿体和蓝细菌的Rubisco基因的序列同源性要低得多。这清楚地表明红藻门和褐藻门的质体之间存在密切的系统发育关系，它们似乎是从叶绿体独立进化而来的（多源起源）。我们的数据表明，褐藻门和隐藻门的质体起源于内共生单细胞红藻。令人惊讶的是，红藻和褐藻的Rubisco与氢细菌的Rubisco的同源程度明显高于与蓝细菌的同源程度。
