Atmospheric carbon monoxide oxidation is a widespread mechanism supporting microbial survival
Atmospheric carbon monoxide oxidation is a widespread mechanism supporting microbial survival
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DOI：
10.1038/s41396-019-0479-8
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发表时间：
2019-11-01
期刊：
影响因子：
11
通讯作者：
Greening, Chris
中科院分区：
文献类型：
--
作者：
Cordero, Paul R. F.;Bayly, Katherine;Greening, Chris
一氧化碳（CO）是一种普遍存在的大气痕量气体，由自然和人为来源产生。一些好氧细菌可以氧化大气中的一氧化碳，它们每年从大气中净损失的一氧化碳约为250太克。然而，这一过程的生理作用、遗传基础和生态分布仍然没有完全解决。在这项工作中，我们通过基于文化和独立于文化的工作来解决这些知识差距。我们证实，通过鸟枪蛋白质组学和转录分析，遗传上易处理的好氧土壤放线菌耻垢分枝杆菌upregulates表达的形式I的铜-铜一氧化碳脱氢酶50倍时耗尽的有机碳底物。在野生型和突变体背景的全细胞生物化学测定证实，这种生物体有氧呼吸CO，包括在低于大气压的浓度，使用酶。与目前的CO氧化范例相反，该酶不支持chemolithoautotrophic生长，并被用于CO解毒。然而，它显着提高了长期生存，这表明大气中的CO在有机碳饥饿期间作为补充能源。系统发育分析表明，大气CO氧化广泛存在，并且是CO脱氢酶的祖先特征。Homestrase酶由685种测序的细菌和古细菌编码，包括来自7个优势土壤门，我们证实编码这种酶的基因是丰富的，并在陆地和海洋环境中表达。在此基础上，我们提出了一个新的生存为中心的有氧CO氧化的演变模型，并得出结论，像大气中的H-2，大气中的CO是一个主要的能源支持持久的好氧异养细菌在剥夺或多变的环境。
Carbon monoxide (CO) is a ubiquitous atmospheric trace gas produced by natural and anthropogenic sources. Some aerobic bacteria can oxidize atmospheric CO and, collectively, they account for the net loss of similar to 250 teragrams of CO from the atmosphere each year. However, the physiological role, genetic basis, and ecological distribution of this process remain incompletely resolved. In this work, we addressed these knowledge gaps through culture-based and culture-independent work. We confirmed through shotgun proteomic and transcriptional analysis that the genetically tractable aerobic soil actinobacterium Mycobacterium smegmatis upregulates expression of a form I molydenum-copper carbon monoxide dehydrogenase by 50-fold when exhausted for organic carbon substrates. Whole-cell biochemical assays in wild-type and mutant backgrounds confirmed that this organism aerobically respires CO, including at sub-atmospheric concentrations, using the enzyme. Contrary to current paradigms on CO oxidation, the enzyme did not support chemolithoautotrophic growth and was dispensable for CO detoxification. However, it significantly enhanced long-term survival, suggesting that atmospheric CO serves a supplemental energy source during organic carbon starvation. Phylogenetic analysis indicated that atmospheric CO oxidation is widespread and an ancestral trait of CO dehydrogenases. Homologous enzymes are encoded by 685 sequenced species of bacteria and archaea, including from seven dominant soil phyla, and we confirmed genes encoding this enzyme are abundant and expressed in terrestrial and marine environments. On this basis, we propose a new survival-centric model for the evolution of aerobic CO oxidation and conclude that, like atmospheric H-2, atmospheric CO is a major energy source supporting persistence of aerobic heterotrophic bacteria in deprived or changeable environments.