Imhoff Johannes F, Rahn Tanja, Künzel Sven, Neulinger Sven C
Research Unit Marine Microbiology, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany.
Max Planck Institute for Evolutionary Biology, Plön, Germany.
Front Microbiol. 2018 Jan 23;8:2679. doi: 10.3389/fmicb.2017.02679. eCollection 2017.
Two different photosystems for performing bacteriochlorophyll-mediated photosynthetic energy conversion are employed in different bacterial phyla. Those bacteria employing a photosystem II type of photosynthetic apparatus include the phototrophic purple bacteria (Proteobacteria), and with their photosynthetic relatives. The proteins of the photosynthetic reaction center PufL and PufM are essential components and are common to all bacteria with a type-II photosynthetic apparatus, including the anaerobic as well as the aerobic phototrophic Proteobacteria. Therefore, PufL and PufM proteins and their genes are perfect tools to evaluate the phylogeny of the photosynthetic apparatus and to study the diversity of the bacteria employing this photosystem in nature. Almost complete gene sequences and the derived protein sequences from 152 type strains and 45 additional strains of phototrophic Proteobacteria employing photosystem II were compared. The results give interesting and comprehensive insights into the phylogeny of the photosynthetic apparatus and clearly define Chromatiales, Rhodobacterales, Sphingomonadales as major groups distinct from other Alphaproteobacteria, from Betaproteobacteria and from Caulobacterales (). A special relationship exists between the PufLM sequences of those bacteria employing bacteriochlorophyll instead of bacteriochlorophyll . A clear phylogenetic association of aerobic phototrophic purple bacteria to anaerobic purple bacteria according to their PufLM sequences is demonstrated indicating multiple evolutionary lines from anaerobic to aerobic phototrophic purple bacteria. The impact of pufLM gene sequences for studies on the environmental diversity of phototrophic bacteria is discussed and the possibility of their identification on the species level in environmental samples is pointed out.
不同细菌门类采用两种不同的光系统来进行细菌叶绿素介导的光合能量转换。那些采用光系统II型光合装置的细菌包括光合性紫色细菌（变形菌门）及其光合亲缘菌。光合反应中心的PufL和PufM蛋白是必需成分，对于所有具有II型光合装置的细菌都是共有的，包括厌氧以及需氧的光合变形菌。因此，PufL和PufM蛋白及其基因是评估光合装置系统发育以及研究自然界中采用该光系统的细菌多样性的理想工具。比较了来自152个模式菌株和另外45个采用光系统II的光合变形菌菌株的几乎完整的基因序列和推导的蛋白质序列。结果为光合装置的系统发育提供了有趣且全面的见解，并明确将色菌目、红杆菌目、鞘脂单胞菌目定义为与其他α-变形菌、β-变形菌和柄杆菌目不同的主要类群。采用细菌叶绿素a而非细菌叶绿素b的那些细菌的PufLM序列之间存在特殊关系。根据其PufLM序列证明了需氧光合紫色细菌与厌氧紫色细菌之间存在明确的系统发育关联，表明从厌氧光合紫色细菌到需氧光合紫色细菌有多个进化路线。讨论了pufLM基因序列对光合细菌环境多样性研究的影响，并指出了在环境样品中在物种水平上鉴定它们的可能性。
