Research press release


Nature Microbiology

Life began in an iron-rich hot spring


あらゆる細胞のLUCAという概念は、初期進化や生命の起源の研究では重要である。しかし、LUCAがどのような場所でどのような仕組みで生きていたのかについては、ほとんど情報がない。William Martinたちは、LUCAに起源を持つ可能性のある古代の遺伝子を探すため、原核生物(単細胞)のタンパク質コード遺伝子610万個の進化上の関係を解析した。


同時掲載のNews & Views記事では、James McInerneyが、「推定されたこのLUCAの代謝を見ると、細菌と古細菌の分岐よりも前から、地球に有力で極めて効率の良い代謝系が存在したのを見る思いだ。この研究は、40億年も昔の生命について、非常に興味深い手掛かりを与えてくれる。」と述べている。

Key metabolic features of the organism from which all life evolved, and the type of environment in which it likely lived, are identified in a paper published online this week in Nature Microbiology. The genomic data analysis finds that the so-called last universal common ancestor (LUCA) was adapted to survive in warm, oxygen-free, mineral-rich environments, perhaps similar to hot springs we see on Earth today.

The concept of a LUCA for all cells is central to the study of early evolution and the origin of life. However, little information exists about how and where LUCA lived. William Martin and colleagues analysed the evolutionary relationships of 6.1 million prokaryotic (single-celled) protein-encoding genes to search for ancient genes that may have originated from LUCA.

Although only 355 protein groups met their strict criteria, they found this was enough to determine that LUCA was anaerobic (did not require oxygen for growth) and thermophilic (thrived at relatively high temperature), and used carbon dioxide, nitrogen and hydrogen to sustain its metabolic pathways. The authors find LUCA was also dependent on transition metals such as iron, and other elements such as selenium. Based on these evolutionary relationships, they conclude that some organisms alive today have similar lifestyles to LUCA, including the clostridia (Bacteria) and methanogens (Archaea). This work provides new evidence to support the theory that life on Earth today is descended from autotrophic organisms - which create nutritional organic substances from inorganic substances, such as CO2 - in a hydrothermal environment.

In an accompanying News & Views article, James McInerney writes: “When we look at the inferred metabolism of LUCA, we are looking at the dominant and most successful kind of metabolism on the planet before the Bacteria and Archaea diverged. This new study provides us with a very intriguing insight into life four billion years ago.”

doi: 10.1038/nmicrobiol.2016.116

「Nature 関連誌注目のハイライト」は、ネイチャー広報部門が報道関係者向けに作成したリリースを翻訳したものです。より正確かつ詳細な情報が必要な場合には、必ず原著論文をご覧ください。

メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週最新のNature 関連誌のハイライトを皆様にお届けいたします。