Molecular Origins of Transcriptional Heterogeneity in Diazotrophic Klebsiella oxytoca.
Molecular Origins of Transcriptional Heterogeneity in Diazotrophic Klebsiella oxytoca.
复制标题
DOI：
10.1128/msystems.00596-22
复制
发表时间：
2022-10-26
期刊：
影响因子：
6.4
通讯作者：
中科院分区：
文献类型：
--
作者：
克隆细菌分批培养中的表型异质性已被证明是一系列细菌系统;然而，这种异质性的分子起源及其程度还不清楚。在极端低氮胁迫条件下，模式固氮菌Klebsiella oxytoca的nifHDK基因表达具有高度的异质性，该基因编码固氮酶的结构基因，是全球氮循环的关键酶之一。这种异质性限制了大量观察到的固氮能力的人口。使用双探针，单细胞RNA荧光原位杂交，我们相关的nifHDK的表达与nifLA和glnK-amtB，这是主要的上游调控成分的代码。通过随机转录模型和互信息分析，我们揭示了固氮酶表达异质性的可能分子起源。在野生型和调节变体中，我们发现nifHDK转录本质上是突发性的，但我们确定通过信号传导的噪声传播也很重要。调节基因glnK对nifHDK变异的影响最大，而来自调节途径外因素的噪声可以忽略不计。了解固氮酶表达的内在异质性及其起源的基础可以为寻求增强生物固氮的生物技术策略提供信息。最后，我们推测在自然土壤环境中固氮生物异质性的潜在好处。氮是植物和动物生命所必需的微量营养素，自然存在于反应性和惰性化学形式中。现代农业严重依赖于通过能量昂贵的Haber-Bosch过程“固定”为反应形式的氮，这对环境造成了严重影响。固氮细菌为生物技术和农业环境提供了一种固定氮的替代来源，但这依赖于对单个细菌细胞内固定过程如何调节的坚定理解。我们研究了一种自由生活的细菌产酸克雷伯氏菌固氮行为的细胞间变异性。我们的研究的意义不仅在于识别显著变异的存在，而且还在于识别引起变异的具体机制，这种理解使我们深入了解了变异行为的进化优势以及生物技术应用的策略。
Phenotypic heterogeneity in clonal bacterial batch cultures has been shown for a range of bacterial systems; however, the molecular origins of such heterogeneity and its magnitude are not well understood. Under conditions of extreme low-nitrogen stress in the model diazotroph Klebsiella oxytoca, we found remarkably high heterogeneity of nifHDK gene expression, which codes for the structural genes of nitrogenase, one key enzyme of the global nitrogen cycle. This heterogeneity limited the bulk observed nitrogen-fixing capacity of the population. Using dual-probe, single-cell RNA fluorescent in situ hybridization, we correlated nifHDK expression with that of nifLA and glnK-amtB, which code for the main upstream regulatory components. Through stochastic transcription models and mutual information analysis, we revealed likely molecular origins for heterogeneity in nitrogenase expression. In the wild type and regulatory variants, we found that nifHDK transcription was inherently bursty, but we established that noise propagation through signaling was also significant. The regulatory gene glnK had the highest discernible effect on nifHDK variance, while noise from factors outside the regulatory pathway were negligible. Understanding the basis of inherent heterogeneity of nitrogenase expression and its origins can inform biotechnology strategies seeking to enhance biological nitrogen fixation. Finally, we speculate on potential benefits of diazotrophic heterogeneity in natural soil environments. IMPORTANCE Nitrogen is an essential micronutrient for both plant and animal life and naturally exists in both reactive and inert chemical forms. Modern agriculture is heavily reliant on nitrogen that has been “fixed” into a reactive form via the energetically expensive Haber-Bosch process, with significant environmental consequences. Nitrogen-fixing bacteria provide an alternative source of fixed nitrogen for use in both biotechnological and agricultural settings, but this relies on a firm understanding of how the fixation process is regulated within individual bacterial cells. We examined the cell-to-cell variability in the nitrogen-fixing behavior of Klebsiella oxytoca, a free-living bacterium. The significance of our research is in identifying not only the presence of marked variability but also the specific mechanisms that give rise to it. This understanding gives insight into both the evolutionary advantages of variable behavior as well as strategies for biotechnological applications.
登录
查看更多内容
影响因子：
3.2
作者：
Jack, R;De Zamaroczy, M;Merrick, M
通讯作者：
Merrick, M
影响因子：
--
作者：
Lenive O;W Kirk PD;H Stumpf MP
通讯作者：
H Stumpf MP
影响因子：
2
作者：
KO, MSH
通讯作者：
KO, MSH
DOI：
10.1016/0304-4165(66)90383-7
发表时间：
1966-01-01
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
DILWORTH, MJ
通讯作者：
DILWORTH, MJ
影响因子：
2.1
作者：
Arcondéguy, T;van Heeswijk, WC;Merrick, M
通讯作者：
Merrick, M