Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA.
Plant J. 2010 Apr 1;62(1):64-76. doi: 10.1111/j.1365-313X.2010.04127.x. Epub 2010 Jan 7.
In recent years there has been much interest in the genetic enhancement of plant metabolism; however, attempts at genetic modification are often unsuccessful due to an incomplete understanding of network dynamics and their regulatory properties. Kinetic modeling of plant metabolic networks can provide predictive information on network control and response to genetic perturbations, which allow estimation of flux at any concentration of intermediate or enzyme in the system. In this research, a kinetic model of the benzenoid network was developed to simulate whole network responses to different concentrations of supplied phenylalanine (Phe) in petunia flowers and capture flux redistributions caused by genetic manipulations. Kinetic parameters were obtained by network decomposition and non-linear least squares optimization of data from petunia flowers supplied with either 75 or 150 mm(2)H(5)-Phe. A single set of kinetic parameters simultaneously accommodated labeling and pool size data obtained for all endogenous and emitted volatiles at the two concentrations of supplied (2)H(5)-Phe. The generated kinetic model was validated using flowers from transgenic petunia plants in which benzyl CoA:benzyl alcohol/phenylethanol benzoyltransferase (BPBT) was down-regulated via RNAi. The determined in vivo kinetic parameters were used for metabolic control analysis, in which flux control coefficients were calculated for fluxes around the key branch point at Phe and revealed that phenylacetaldehyde synthase activity is the primary controlling factor for the phenylacetaldehyde branch of the benzenoid network. In contrast, control of flux through the beta-oxidative and non-beta-oxidative pathways is highly distributed.
近年来，人们对植物代谢的遗传增强产生了浓厚的兴趣；然而，由于对网络动态及其调节特性的不完全了解，遗传修饰的尝试往往不成功。植物代谢网络的动力学建模可以提供有关网络控制和对遗传扰动的响应的预测信息，这允许在系统中任何中间物或酶浓度下估计通量。在这项研究中，开发了苯环网络的动力学模型，以模拟苯环网络对不同浓度供给的苯丙氨酸（Phe）的整体网络响应，并捕获遗传操作引起的通量再分配。动力学参数通过网络分解和非线性最小二乘优化来自供应 75 或 150 mm(2)H(5)-Phe 的矮牵牛花的数据获得。一组动力学参数同时适应了在两种浓度的供给 (2)H(5)-Phe 下获得的所有内源性和发射挥发性物质的标记和池大小数据。使用通过 RNAi 下调苯丙氨酸苄基 CoA：苄基醇/苯乙醇苯甲酰基转移酶（BPBT）的转基因矮牵牛植物的花朵验证了生成的动力学模型。确定的体内动力学参数用于代谢控制分析，其中计算了苯环网络中 Phe 处关键分支点周围的通量控制系数，并揭示了苯乙醛合酶活性是苯环网络中苯乙醛分支的主要控制因素。相比之下，通过β-氧化和非β-氧化途径的通量控制是高度分布的。
