EAGER: A System Identification Based Metabolic Flux Analysis and its Application to Production of Advanced Biofuels

随着基因组规模代谢网络模型的可用性，鉴定用于过量生产生物燃料和其它有价值的化学品的突变株的计算方法被广泛使用。然而，在大规模计算模型产生的复杂结果与生物学家容易理解和直接利用的有生物学意义的知识之间存在着显著的差距。EAGER项目将通过开发一种新的基于系统识别的代谢通量分析工具，推动系统代谢工程的发展。这样的工具不仅能使我们弥合上述差距，还有助于推断细胞调控机制。值得注意的是，尽管系统识别是一个成熟的领域，并已在许多领域得到广泛应用，但由于缺乏系统识别工具所需的高质量数据，其在代谢工程中的拟议应用尚属首次。通过将专门设计的计算机微扰实验与系统识别工具相结合，复杂网络结构中包含的生物学意义信息将被提取出来，并以生物学家易于理解的形式呈现。该方法将在E. coli和革兰氏阳性菌S.这个EAGER项目将是第一个将系统识别技术扩展到研究基因组规模代谢网络的项目。 所提取的生物信息不仅提供了对细胞调控机制的见解，而且使得能够使用通常本质上是定性的现有生物学知识来验证代谢网络模型。 通过E. coli和革兰氏阳性菌S. 酿酒酵母在先进生物燃料生产方面的研究，将获得关于突变菌株如何调节其细胞代谢的有价值的知识，并将作为未来定期提案的基础。所提出的方法可用于研究各种微生物以及其他活细胞（如癌细胞）的细胞代谢，只要它们的代谢网络模型可用。细胞调控机制的发现将对代谢工程、先进生物燃料、应用微生物学、药物开发等领域产生重大影响。 此外，该方法的基本思想还可以推广到其他细胞网络的研究中，如基因调控网络和信号转导网络，从而从大量的计算机模拟数据中提取有价值的信息.

1248388WangWith the availability of the genome-scale metabolic network models, computational procedures that identify mutant strains for over production of biofuels and other valuable chemicals are widely in use. However, there is a significant gap between the complicated results generated from large-scale computational models and biologically meaningful knowledge that can be easily appreciated and directly utilized by biologists. Such a gap limits the potential impact of genome-scale models on metabolic engineering.This EAGER project will advance the state-of-the-art in systems metabolic engineering through the development of a new systems identification based metabolic flux analysis tool. Such a tool will not only enable us to bridge the aforementioned gap, but also help infer cellular regulatory mechanisms. It is worth noting that although system identification is a well-established field and has been widely used in many areas, its proposed application to metabolic engineering is the first due to the lack of quality data required by the system identification tools. By combining the specially designed in silico perturbation experiments with system identification tools, biologically meaningful information contained in the complex network structure will be extracted and presented in the form that is easily interpretable by biologists. The proposed approach will be validated using E. coli and S. cerevisiae as the model systems with the focus on the production of advanced biofuels.This EAGER project will be the first to extend the system identification techniques to study genome-scale metabolic networks. The extracted biological information will not only provide insights on cellular regulatory mechanism, but also enable the validation of metabolic network models using existing biological knowledge that are often qualitative in nature. By validating the proposed approach with E. coli and S. cerevisiae on advanced biofuels production, valuable knowledge on how mutant strains regulate their cellular metabolism will be obtained and will serve as part of the foundation for a future regular proposal.The proposed approach can be applied to study cellular metabolism of various microorganisms as well as other living cells, such as cancer cells, as long as their metabolic network models are available. The discovered knowledge on cellular regulation mechanisms will have significant impact on metabolic engineering, advanced biofuels, applied microbiology, drug discovery and other areas. In addition, the basic idea of the proposed approach can be extended to study other cellular networks, such as gene regulatory networks and signal transduction networks, to extract valuable information from massive amount of data generated through in silico experiments.