Phylogenetic analyses of two "Archaeal" genes in Thermotoga maritima reveal multiple transfers between Archaea and Bacteria
Phylogenetic analyses of two "Archaeal" genes in Thermotoga maritima reveal multiple transfers between Archaea and Bacteria
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DOI：
10.1093/oxfordjournals.molbev.a003812
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发表时间：
2001-03-01
影响因子：
10.7
通讯作者：
Doolittle, WF
中科院分区：
文献类型：
--
作者：
Nesbo, CL;L'Haridon, S;Doolittle, WF
海栖热袍菌的基因组序列显示，在 BLAST 分析中，其 24% 的开放阅读框 (ORF) 与古菌基因的相似性得分最高。在这里，我们筛选了来自栖热袍菌属和其他相关栖热袍菌目的 16 个菌株，以发现其中两个“古菌”基因的出现：编码谷氨酸合酶大亚基 (gltB) 的基因和 mpo-肌醇 1P 合酶基因 (ino1)。这两个基因都仅限于栖热袍菌目中的栖热袍菌属。这两个基因的分布以及系统发育分析的结果表明，它们是在栖热袍菌目分化期间从古细菌中获得的。数据库搜索显示，另外三种细菌——Dehalococcoides ethenogenes、苜蓿中华根瘤菌和艰难梭菌——拥有古细菌型gltB，系统发育分析证实了细菌和古细菌之间至少有两个横向基因转移（LGT）事件。这些 LGT 事件也得到了基因结构数据的有力支持，因为细菌型 gltB 中的三个结构域与古细菌和具有古细菌型 gltB 的细菌中的三个独立 ORF 同源。 ino1基因在细菌中分布较分散，除了栖热袍菌菌株外，仅在Aquifex aeolicus、D.ethenogenes和一些高G+C革兰氏阳性菌中发现。 ino1 序列的系统发育分析揭示了三个高度支持的原核进化枝，全部含有古细菌和细菌序列的混合物，并表明所有细菌 ino1 基因都是从古细菌供体中招募的。 Thermotoga 菌株和 A. aeolicus 独立地从不同的古细菌物种中获得了该基因。尽管来自超嗜热古菌的基因转移可能促进了细菌超嗜热的进化，但域间转移也会影响嗜温物种。对于超级嗜热菌，我们假设 LGT 可能是适应超级嗜热菌的结果和原因。
The genome sequence of Thermotoga maritima revealed that 24% of its open reading frames (ORFs) showed the highest similarity scores to archaeal genes in BLAST analyses. Here we screened 16 strains from the genus Thermotoga and other related Thermotogales for the occurrence of two of these "archaeal" genes: the gene encoding the large subunit of glutamate synthase (gltB) and the mpo-inositol 1P synthase gene (ino1). Both genes were restricted to the Thermotoga species within the Thermotogales. The distribution of the two genes, along with results from phylogenetic analyses, showed that they were acquired from Archaea during the divergence of the Thermotogales. Database searches revealed that three other bacteria-Dehalococcoides ethenogenes, Sinorhizobium meliloti, and Clostridium difficile-possess archaeal-type gltBs, and the phylogenetic analyses confirmed at least two lateral gene transfer (LGT) events between Bacteria and Archaea. These LGT events were also strongly supported by gene structure data, as the three domains in bacterial-type gltB are homologous to three independent ORFs in Archaea and Bacteria with archaeal-type gltBs. The ino1 gene has a scattered distribution among Bacteria, and apart from the Thermotoga strains it is found only in Aquifex aeolicus, D. ethenogenes, and some high-G + C Gram-positive bacteria. Phylogenetic analysis of the ino1 sequences revealed three highly supported prokaryotic clades, all containing a mixture of archaeal and bacterial sequences, and suggested that all bacterial ino1 genes had been recruited from archaeal donors. The Thermotoga strains and A. aeolicus acquired this gene independently from different archaeal species. Although transfer of genes from hyperthermophilic Archaea may have facilitated the evolution of bacterial hyperthermophily, between-domain transfers also affect mesophilic species. For hyperthermophiles, we hypothesize that LGT may be as much a consequence as the cause of adaptation to hyperthermophily.