PDF(Pubmed)
Abstract：
Methanogenic archaea play a key role in the global carbon cycle because these microorganisms remineralize organic compounds in various anaerobic environments. The microorganism Methanosarcina barkeri is a metabolically versatile methanogen, which can utilize acetate, methanol, and H2/CO2 to synthesize methane. However, the regulatory mechanisms underlying methanogenesis for different substrates remain unknown. In this study, RNA-seq analysis was used to investigate M. barkeri growth and gene transcription under different substrate regimes. According to the results, M. barkeri showed the best growth under methanol, followed by H2/CO2 and acetate, and these findings corresponded well with the observed variations in genes transcription abundance for different substrates. In addition, we identified a novel regulator, MSBRM_RS03855 (designated as HdrR), which specifically activates the transcription of the heterodisulfide reductase hdrBCA operon in M. barkeri. HdrR was able to bind to the hdrBCA operon promoter to regulate transcription. Furthermore, the structural model analyses revealed a helix-turn-helix domain, which is likely involved in DNA binding. Taken together, HdrR serves as a model to reveal how certain regulatory factors control the expression of key enzymes in the methanogenic pathway.IMPORTANCEThe microorganism Methanosarcina barkeri has a pivotal role in the global carbon cycle and contributes to global temperature homeostasis. The consequences of biological methanogenesis are far-reaching, including impacts on atmospheric methane and CO2 concentrations, agriculture, energy production, waste treatment, and human health. As such, reducing methane emissions is crucial to meeting set climate goals. The methanogenic activity of certain microorganisms can be drastically reduced by inhibiting the transcription of the hdrBCA operon, which encodes heterodisulfide reductases. Here, we provide novel insight into the mechanisms regulating hdrBCA operon transcription in the model methanogen M. barkeri. The results clarified that HdrR serves as a regulator of heterodisulfide reductase hdrBCA operon transcription during methanogenesis, which expands our understanding of the unique regulatory mechanisms that govern methanogenesis. The findings presented in this study can further our understanding of how genetic regulation can effectively reduce the methane emissions caused by methanogens.
摘要：
产甲烷古细菌在全球碳循环中起着关键作用，因为这些微生物在各种厌氧环境中使有机化合物再矿化。巴氏甲烷微生物是一种代谢通用的产甲烷菌，可以利用醋酸盐，甲醇,和H2/CO2合成甲烷。然而,不同底物产甲烷的调节机制尚不清楚。在这项研究中,使用RNA-seq分析来研究在不同底物方案下的M.barkeri生长和基因转录。根据结果,M.barkeri在甲醇下表现出最好的生长，其次是H2/CO2和乙酸盐，这些发现与观察到的不同底物的基因转录丰度变化非常吻合。此外,我们确定了一个新的调节器，MSBRM_RS03855(指定为HdrR),特异性激活M.barkeri中异二硫化物还原酶hdrBCA操纵子的转录。HdrR能够与hdrBCA操纵子启动子结合以调节转录。此外，结构模型分析揭示了一个螺旋-转角-螺旋结构域，这可能与DNA结合有关。一起来看,HdrR用作揭示某些调节因子如何控制产甲烷途径中关键酶的表达的模型。重要的是，巴氏甲烷微生物在全球碳循环中起着关键作用，并有助于全球温度稳态。生物产甲烷的后果是深远的，包括对大气甲烷和二氧化碳浓度的影响，农业,能源生产，废物处理,和人类健康。因此，减少甲烷排放对于实现设定的气候目标至关重要。某些微生物的产甲烷活性可以通过抑制hdrBCA操纵子的转录而大大降低，它编码异二硫化物还原酶。这里,我们提供了在模型产甲烷菌M.barkeri中调节hdrBCA操纵子转录的机制的新见解。结果阐明，HdrR在产甲烷过程中充当异二硫化物还原酶hdrBCA操纵子转录的调节剂，这扩大了我们对控制甲烷生成的独特调节机制的理解。这项研究中提出的发现可以进一步了解遗传调控如何有效减少产甲烷菌引起的甲烷排放。
