Molecular evidence for the early evolution of photosynthesis
Molecular evidence for the early evolution of photosynthesis
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DOI：
10.1126/science.289.5485.1724
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发表时间：
2000-09-08
期刊：
影响因子：
56.9
通讯作者：
Bauer, CE
中科院分区：
文献类型：
--
作者：
Xiong, J;Fischer, WM;Bauer, CE
由于缺乏整个光合域的光合作用基因序列信息，光合作用的起源和进化长期以来一直是个谜。为了探索光合作用的早期进化史，我们从绿色硫磺细菌Chlorobium tepidum和绿色非硫细菌Chlorofleus aurantiacus中获得了一些光合作用基因的新序列信息。在约100kb的基因组序列中，共鉴定出31个开放阅读框，编码参与细菌-叶绿素/卟啉生物合成、类胡萝卜素生物合成和光合作用电子传递的酶。采用距离法、最大简约法和最大似然法相结合的方法对多个镁-四吡咯生物合成基因进行了系统发育分析，结果表明，幽门螺杆菌是所有产氧光合作用谱系的最后共同祖先，绿色硫磺细菌和绿色非硫细菌是彼此最近的亲缘关系。简约和距离分析进一步确定紫色细菌是最早出现的光合作用谱系。这些结果挑战了以前基于16S核糖体RNA和Hsp60/Hsp70分析的结论，即绿色非硫细菌或螺旋杆菌是最早的光养生物。我们系统发育分析的总体共识，即细菌-叶绿素生物合成先于叶绿素生物合成，也与长期持有的格兰尼克假说背道而驰。
The origin and evolution of photosynthesis have Long remained enigmatic due to a Lack of sequence information of photosynthesis genes across the entire photosynthetic domain. To probe early evolutionary history of photosynthesis, we obtained new sequence information of a number of photosynthesis genes from the green sulfur bacterium Chlorobium tepidum and the green nonsulfur bacterium Chloroflexus aurantiacus. A total of 31 open reading frames that encode enzymes involved in bacteriochlorophyll/porphyrin biosynthesis, carotenoid biosynthesis, and photosynthetic electron transfer were identified in about 100 kilobase pairs of genomic sequence. Phylogenetic analyses of multiple magnesium-tetrapyrrole biosynthesis genes using a combination of distance, maximum parsimony, and maximum likelihood methods indicate that heliobacteria are closest to the Last common ancestor of all oxygenic photosynthetic Lineages and that green sulfur bacteria and green nonsulfur bacteria are each other's closest relatives. Parsimony and distance analyses further identify purple bacteria as the earliest emerging photosynthetic Lineage. These results challenge previous conclusions based on 16S ribosomal RNA and Hsp60/Hsp70 analyses that green nonsulfur bacteria or heliobacteria are the earliest phototrophs. The overall consensus of our phylogenetic analysis, that bacteriochlorophyll biosynthesis evolved before chlorophyll biosynthesis, also argues against the long-held Granick hypothesis.