Imhoff Johannes F, Rahn Tanja, Künzel Sven, Neulinger Sven C
GEOMAR Helmholtz Centre for Ocean Research, 24105 Kiel, Germany.
Max Planck Institute for Evolutionary Biologie, 24306 Plön, Germany.
Microorganisms. 2019 Nov 19;7(11):576. doi: 10.3390/microorganisms7110576.
Photosynthesis is a key process for the establishment and maintenance of life on earth, and it is manifested in several major lineages of the prokaryote tree of life. The evolution of photosynthesis in anoxygenic photosynthetic bacteria is of major interest as these have the most ancient roots of photosynthetic systems. The phylogenetic relations between anoxygenic phototrophic bacteria were compared on the basis of sequences of key proteins of the type-II photosynthetic reaction center, including PufLM and PufH (PuhA), and a key enzyme of bacteriochlorophyll biosynthesis, the light-independent chlorophyllide reductase BchXYZ. The latter was common to all anoxygenic phototrophic bacteria, including those with a type-I and those with a type-II photosynthetic reaction center. The phylogenetic considerations included cultured phototrophic bacteria from several phyla, including (138 species), (five species), (six species), as well as , and . Whenever available, type strains were studied. Phylogenetic relationships based on a photosynthesis tree (PS tree, including sequences of PufHLM-BchXYZ) were compared with those of 16S rRNA gene sequences (RNS tree). Despite some significant differences, large parts were congruent between the 16S rRNA phylogeny and photosynthesis proteins. The phylogenetic relations demonstrated that bacteriochlorophyll biosynthesis had evolved in ancestors of phototrophic green bacteria much earlier as compared to phototrophic purple bacteria and that multiple events independently formed different lineages of aerobic phototrophic purple bacteria, many of which have very ancient roots. The clearly represented the youngest group, which was separated from other by a large evolutionary gap.
光合作用是地球上生命建立和维持的关键过程，它体现在原核生物生命树的几个主要谱系中。无氧光合细菌中光合作用的进化备受关注，因为这些细菌拥有光合系统最古老的根源。基于II型光合反应中心关键蛋白的序列，包括PufLM和PufH（PuhA），以及细菌叶绿素生物合成的关键酶——不依赖光的叶绿素还原酶BchXYZ，对无氧光合细菌之间的系统发育关系进行了比较。后者在所有无氧光合细菌中都存在，包括具有I型和II型光合反应中心的细菌。系统发育研究包括来自几个门的培养光合细菌，包括（138种）、（5种）、（6种），以及、和。只要有可用的菌株，就对模式菌株进行研究。将基于光合作用树（PS树，包括PufHLM - BchXYZ的序列）的系统发育关系与16S rRNA基因序列（RNS树）的关系进行了比较。尽管存在一些显著差异，但16S rRNA系统发育和光合作用蛋白之间的大部分是一致的。系统发育关系表明，与光合紫色细菌相比，细菌叶绿素生物合成在光合绿色细菌的祖先中进化得更早，并且多个事件独立形成了需氧光合紫色细菌的不同谱系，其中许多谱系有非常古老的根源。明显代表了最年轻的群体，它与其他群体之间存在很大的进化差距。
