Oxygen Reductases in Alphaproteobacterial Genomes: Physiological Evolution From Low to High Oxygen Environments
Oxygen Reductases in Alphaproteobacterial Genomes: Physiological Evolution From Low to High Oxygen Environments
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DOI：
10.3389/fmicb.2019.00499
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发表时间：
2019-03-18
影响因子：
5.2
通讯作者：
Sousa, Filipa L.
中科院分区：
文献类型：
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作者：
Degli Esposti, Mauro;Mentel, Marek;Sousa, Filipa L.
氧还原末端氧化酶的亚基组成、血红素基团、操纵子结构和对O-2的亲和力不同。目前已知有六个末端氧化酶家族，它们都存在于α-变形菌基因组中，其中两个也存在于线粒体中。许多α-变形菌编码几种不同的末端氧化酶，可能反映了氧水平的生态多样性。末端氧化酶的进化可能始于大约24亿年前O-2的出现，末端氧化酶在元古代多样化，在此期间氧水平保持较低，大约在巴斯德点（约1000年）。2 μ M O-2）。在所调查的α-变形菌基因组中，来自杜鹃花科成员的基因组揭示了氧还原酶的最大多样性。一些港口所有六个终端氧化酶类型，除了许多可溶性酶典型的厌氧发酵线粒体和氢化酶体的真核生物。最近的数据表明，O-2水平增加到目前的值（21% v/v或约。250亩米）只有约4.3亿年前。生态适应产生了不同谱系的α-变形菌和不同谱系的真核生物，它们经历了高氧、低氧和厌氧生境的进化特化。有些仍然是兼性厌氧菌，能够在有或没有氧气的帮助下产生ATP，并代表与线粒体和真核生物起源的古老变形菌谱系的生理联系。我们的分析表明，α-变形菌的基因组似乎保留了有氧代谢中古老转变的特征，这些发现也与真核生物中的线粒体进化有关。
Oxygen reducing terminal oxidases differ with respect to their subunit composition, heme groups, operon structure, and affinity for O-2. Six families of terminal oxidases are currently recognized, all of which occur in alphaproteobacterial genomes, two of which are also present in mitochondria. Many alphaproteobacteria encode several different terminal oxidases, likely reflecting ecological versatility with respect to oxygen levels. Terminal oxidase evolution likely started with the advent of O-2 roughly 2.4 billion years ago and terminal oxidases diversified in the Proterozoic, during which oxygen levels remained low, around the Pasteur point (ca. 2 mu M O-2). Among the alphaproteobacterial genomes surveyed, those from members of the Rhodospirillaceae reveal the greatest diversity in oxygen reductases. Some harbor all six terminal oxidase types, in addition to many soluble enzymes typical of anaerobic fermentations in mitochondria and hydrogenosomes of eukaryotes. Recent data have it that O-2 levels increased to current values (21% v/v or ca. 250 mu M) only about 430 million years ago. Ecological adaptation brought forth different lineages of alphaproteobacteria and different lineages of eukaryotes that have undergone evolutionary specialization to high oxygen, low oxygen, and anaerobic habitats. Some have remained facultative anaerobes that are able to generate ATP with or without the help of oxygen and represent physiological links to the ancient proteobacterial lineage at the origin of mitochondria and eukaryotes. Our analysis reveals that the genomes of alphaproteobacteria appear to retain signatures of ancient transitions in aerobic metabolism, findings that are relevant to mitochondrial evolution in eukaryotes as well.