Borrel Guillaume, Adam Panagiotis S, Gribaldo Simonetta
Department of Microbiology, Unité De Biologie Moléculaire Du Gène Chez Les Extrêmophiles, Institut Pasteur, Paris, France
Department of Microbiology, Unité De Biologie Moléculaire Du Gène Chez Les Extrêmophiles, Institut Pasteur, Paris, France Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
Genome Biol Evol. 2016 Jun 13;8(6):1706-11. doi: 10.1093/gbe/evw114.
Methanogenesis coupled to the Wood-Ljungdahl pathway is one of the most ancient metabolisms for energy generation and carbon fixation in the Archaea. Recent results are sensibly changing our view on the diversity of methane-cycling capabilities in this Domain of Life. The availability of genomic sequences from uncharted branches of the archaeal tree has highlighted the existence of novel methanogenic lineages phylogenetically distant to previously known ones, such as the Methanomassiliicoccales. At the same time, phylogenomic analyses have suggested a methanogenic ancestor for all Archaea, implying multiple independent losses of this metabolism during archaeal diversification. This prediction has been strengthened by the report of genes involved in methane cycling in members of the Bathyarchaeota (a lineage belonging to the TACK clade), representing the first indication of the presence of methanogenesis outside of the Euryarchaeota. In light of these new data, we discuss how the association between methanogenesis and the Wood-Ljungdahl pathway appears to be much more flexible than previously thought, and might provide information on the processes that led to loss of this metabolism in many archaeal lineages. The combination of environmental microbiology, experimental characterization and phylogenomics opens up exciting avenues of research to unravel the diversity and evolutionary history of fundamental metabolic pathways.
与伍德-Ljungdahl途径偶联的产甲烷作用是古菌中最古老的能量产生和碳固定代谢方式之一。最近的研究结果正在合理地改变我们对这个生命域中甲烷循环能力多样性的看法。来自古菌树未探索分支的基因组序列的可得性突出了新的产甲烷谱系的存在，这些谱系在系统发育上与先前已知的谱系相距甚远，例如甲烷粒菌目。与此同时，系统发育基因组学分析表明所有古菌都有一个产甲烷祖先，这意味着在古菌多样化过程中这种代谢多次独立丧失。嗜温古菌（属于TACK进化枝的一个谱系）成员中参与甲烷循环的基因的报告加强了这一预测，这是广古菌域外存在产甲烷作用的首个迹象。鉴于这些新数据，我们讨论了产甲烷作用与伍德-Ljungdahl途径之间的关联似乎比以前认为的更加灵活，并且可能提供有关导致许多古菌谱系中这种代谢丧失的过程的信息。环境微生物学、实验表征和系统发育基因组学相结合，为揭示基本代谢途径的多样性和进化历史开辟了令人兴奋的研究途径。
