Role of methanobactin in methane oxidation rates in the presence of mineral copper

矿物铜存在下甲烷杆菌素对甲烷氧化速率的作用

• 批准号: NE/F00608X/1
• 负责人: David Graham
• 金额: $ 73.82万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF00608X%2F1
• 关键词: Role; methanobactin; methane; oxidation; rates

Methane-oxidizing bacteria (methanotrophs) are nature's primary mechanism for reducing levels of atmospheric methane, the second most important greenhouse gas. Understanding the abundance and distribution of these key organisms is critical to understanding nature's response to increased anthropogenic production of the gas and other releases, such as warming-mediated melting of permafrost zones. Unfortunately, despite the importance of these organisms, little is known about what controls in situ methanotroph ecology and activity. Factors such as soil moisture, pH, and oxygen, methane, and nitrogen levels have all been considered, and although each conditionally influences methanotroph diversity, none provides a consistent explanation for the abundance of these environmentally critical organisms, nor, the rate at which they destroy methane. Interestingly, copper (Cu), which is central to methanotroph metabolism, has not been studied in detail as a factor affecting in situ methanotroph activity, which is surprising since Cu is a component of particulate methane monooxygenase (pMMO), the most efficient enzyme at methane destruction in nature. Fortunately, recent discoveries have provided a possible explanation for why past work on methanotroph ecology has been less than conclusive, which is based on a new class of molecules called methanobactins (mb). mbs are small molecules produced by some methanotrophs that allow them to acquire, transport, and use Cu (i.e., chalkophores), especially from mineral and other more refractory Cu sources in the environment. Specifically, data show that mb conditionally sequesters Cu from iron-oxides and borosilicate glass, which promotes pMMO expression under conditions that would normally not support pMMO expression. Therefore, mb production clearly makes a significant difference in the amount of pMMO within a system and likely provides a competitive advantage to organisms that produce mb, especially within geochemical systems. Further, mb-mediation almost certainly impacts net methane oxidation activity because of the strength of pMMO as a methane-oxidizing agent. Although these observations are promising, little is known about the actual breadth of mb production among methanotrophs, which limits how far we can extend our predictions; i.e., only one mb has been crystallised (from Methylosinus trichosporium OB3b), although three other mbs have been partially characterized, which suggests that more mbs likely exist, but have not yet been found. Therefore, the purpose of this project is to determine the breadth of methanotrophs that produce mb-like compounds, and assess how mb and other factors impact pMMO expression, methanotroph ecology, and methane oxidation rates in geochemical settings. Initial experiments will be performed on twelve different methanotrophs to assess mb production in known strains and types, and in isolates from soils with different native Cu conditions. From this initial set of mbs, a sub-set will be chosen for further purification to compare Cu-binding properties and structures with the one known mb from M. trichosporium OB3b. Simultaneous to these studies, a comprehensive set of experiments assessing the impact of Cu mineralogy, nitrogen source, oxygen level, iron level, and other factors on pMMO expression and methane oxidation patterns will be performed using our model organism, M. trichosporium OB3b. Based on these data and also on the nature of new mbs discovered, final experiments on real soils will be carried out to calibrate Cu availability and MMO expression data from defined mineral sources and different soils collected from natural systems. The ultimate goal of the work is provide the most complete picture yet of what regulates MMO gene expression in geochemical settings. This will better inform future field studies on methanotrophs, assist in climate change studies, and provide a tool for predicting methane oxidation rates based on geochemical information.

甲烷氧化细菌（甲烷氧化菌）是自然界减少大气甲烷（第二重要的温室气体）水平的主要机制。了解这些关键生物体的丰度和分布对于了解自然对人为气体产量增加和其他释放（例如变暖介导的永久冻土带融化）的反应至关重要。不幸的是，尽管这些生物体很重要，但人们对原位甲烷氧化菌生态和活动的控制因素知之甚少。土壤湿度、pH 值以及氧气、甲烷和氮气水平等因素都已被考虑在内，尽管每种因素都会有条件地影响甲烷氧化菌多样性，但没有一个因素能够对这些对环境至关重要的生物体的丰度及其破坏甲烷的速度提供一致的解释。有趣的是，作为甲烷氧化菌代谢的核心的铜（Cu）尚未被详细研究为影响原位甲烷氧化菌活性的因素，这是令人惊讶的，因为铜是颗粒甲烷单加氧酶（pMMO）的组成部分，而pMMO是自然界中破坏甲烷最有效的酶。幸运的是，最近的发现为为什么过去关于甲烷氧化菌生态学的研究尚未得出结论提供了可能的解释，该研究基于一类称为甲烷杆菌素（mb）的新分子。 mbs 是一些甲烷氧化菌产生的小分子，使它们能够获取、运输和使用铜（即铜基团），特别是来自环境中的矿物和其他更难处理的铜源。具体来说，数据显示 mb 有条件地从铁氧化物和硼硅酸盐玻璃中螯合 Cu，从而在通常不支持 pMMO 表达的条件下促进 pMMO 表达。因此，mb 的产生显然会对系统内 pMMO 的数量产生显着影响，并可能为产生 mb 的生物体提供竞争优势，尤其是在地球化学系统中。此外，由于 pMMO 作为甲烷氧化剂的强度，mb 介导几乎肯定会影响净甲烷氧化活性。尽管这些观察结果很有希望，但人们对甲烷氧化菌生产 mb 的实际范围知之甚少，这限制了我们的预测范围。即，只有一种 mb 已结晶（来自毛孢甲基红窦菌 OB3b），尽管其他三种 mb 已部分表征，这表明可能存在更多 mb，但尚未发现。因此，该项目的目的是确定产生 mb 类化合物的甲烷氧化菌的范围，并评估 mb 和其他因素如何影响地球化学环境中的 pMMO 表达、甲烷氧化菌生态和甲烷氧化速率。初步实验将在 12 种不同的甲烷氧化菌上进行，以评估已知菌株和类型以及来自具有不同天然铜条件的土壤的分离株的 mb 产量。从这组初始的 mbs 中，将选择一个子集进行进一步纯化，以将 Cu 结合特性和结构与来自毛孢分枝杆菌 OB3b 的已知 mb 进行比较。在这些研究的同时，将使用我们的模型生物毛孢分枝杆菌 OB3b 进行一组全面的实验，评估铜矿物学、氮源、氧水平、铁水平和其他因素对 pMMO 表达和甲烷氧化模式的影响。根据这些数据以及发现的新 mbs 的性质，将在真实土壤上进行最终实验，以校准来自确定的矿物来源和从自然系统收集的不同土壤的 Cu 可用性和 MMO 表达数据。这项工作的最终目标是提供迄今为止在地球化学环境中调节 MMO 基因表达的最完整的图景。这将更好地为未来甲烷氧化菌的实地研究提供信息，协助气候变化研究，并提供基于地球化学信息预测甲烷氧化速率的工具。

项目成果

Effects of copper mineralogy and methanobactin on cell growth and sMMO activity in <i>Methylosinus trichosporium</i> OB3b

铜矿物学和甲烷菌素对细胞生长和 sMMO 活性的影响

• DOI: 10.5194/bgd-8-2851-2011
• 发表时间: 2011
• 作者: Chi Fru E

Phenotypic Variability in Synthetic Biology Applications: Dealing with Noise in Microbial Gene Expression.

• DOI: 10.3389/fmicb.2016.00479
• 发表时间: 2016
• 期刊: Frontiers in microbiology
• 影响因子: 5.2
• 作者: Bandiera L;Furini S;Giordano E
• 通讯作者: Giordano E

Insight into Metal Removal from Peptides that Sequester Copper for Methane Oxidation.

• DOI: 10.1002/chem.201706035
• 发表时间: 2018-03-26
• 期刊: Chemistry (Weinheim an der Bergstrasse, Germany)
• 作者: Baslé A;El Ghazouani A;Lee J;Dennison C
• 通讯作者: Dennison C

Soil geochemistry confines microbial abundances across an arctic landscape; implications for net carbon exchange with the atmosphere

• DOI: 10.1007/s10533-014-9997-7
• 发表时间: 2014-08-01
• 期刊: BIOGEOCHEMISTRY
• 影响因子: 4
• 作者: Gray, N. D.;McCann, C. M.;Graham, D. W.
• 通讯作者: Graham, D. W.