Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.
Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.
Elife. 2022 Apr 5;11:e76970. doi: 10.7554/eLife.76970.
-Type cytochromes (cyt ) are proteins that undergo post-translational modification to covalently bind heme, which allows them to facilitate redox reactions in electron transport chains across all domains of life. Genomic evidence suggests that cyt are involved in electron transfer processes among the Archaea, especially in members that produce or consume the potent greenhouse gas methane. However, neither the maturation machinery for cyt in Archaea nor their role in methane metabolism has ever been functionally characterized. Here, we have used CRISPR-Cas9 genome editing tools to map a distinct pathway for cyt biogenesis in the model methanogenic archaeon and have also identified substrate-specific functional roles for cyt during methanogenesis. Although the cyt maturation machinery from is universally conserved in the Archaea, our evolutionary analyses indicate that different clades of Archaea acquired this machinery through multiple independent horizontal gene transfer events from different groups of Bacteria. Overall, we demonstrate the convergent evolution of a novel Archaea-specific cyt maturation machinery and its physiological role during methanogenesis, a process which contributes substantially to global methane emissions.
细胞色素（cyt ）是一类经过翻译后修饰，能共价结合血红素的蛋白质，使其能够在所有生命领域的电子传递链中促进氧化还原反应。基因组证据表明，细胞色素在古菌中参与电子传递过程，特别是在产生或消耗强效温室气体甲烷的成员中。然而，古菌中细胞色素的成熟机制及其在甲烷代谢中的作用从未被功能表征过。在这里，我们使用 CRISPR-Cas9 基因组编辑工具来绘制模型产甲烷古菌中细胞色素生物发生的独特途径，并且还确定了细胞色素在甲烷生成过程中的底物特异性功能作用。尽管 的细胞色素成熟机制在古菌中普遍保守，但我们的进化分析表明，不同的古菌分支通过来自不同细菌群体的多次独立水平基因转移事件获得了这种机制。总的来说，我们证明了一种新型的古菌特异性细胞色素成熟机制的趋同进化及其在甲烷生成过程中的生理作用，这个过程对全球甲烷排放有很大贡献。
