School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
New Phytol. 2012 Oct;196(2):414-426. doi: 10.1111/j.1469-8137.2012.04262.x. Epub 2012 Aug 20.
Metabolic control analysis allows the study of metabolic regulation. We applied both single- and double-manipulation top-down control analysis to examine the control of lipid accumulation in developing oilseed rape (Brassica napus) embryos. The biosynthetic pathway was conceptually divided into two blocks of reactions (fatty acid biosynthesis (Block A), lipid assembly (Block B)) connected by a single system intermediate, the acyl-coenzyme A (acyl-CoA) pool. Single manipulation used exogenous oleate. Triclosan was used to inhibit specifically Block A, whereas diazepam selectively manipulated flux through Block B. Exogenous oleate inhibited the radiolabelling of fatty acids from [1-(14)C]acetate, but stimulated that from [U-14C]glycerol into acyl lipids. The calculation of group flux control coefficients showed that c. 70% of the metabolic control was in the lipid assembly block of reactions. Monte Carlo simulations gave an estimation of the error of the resulting group flux control coefficients as 0.27±0.06 for Block A and 0.73±0.06 for Block B. The two methods of control analysis gave very similar results and showed that Block B reactions were more important under our conditions. This contrasts notably with data from oil palm or olive fruit cultures and is important for efforts to increase oilseed rape lipid yields.
代谢控制分析可用于研究代谢调控。我们应用单因素和双因素自上而下控制分析方法来研究油菜胚胎发育过程中脂质积累的控制。生物合成途径概念上被划分为两个反应模块（脂肪酸合成（模块 A），脂质组装（模块 B）），由一个单一的系统中间产物酰基辅酶 A（酰基辅酶 A）池连接。单因素操纵使用外源性油酸。三氯生用于特异性抑制模块 A，而地西泮则选择性地影响模块 B 的通量。外源性油酸抑制了[1-(14)C]乙酸盐标记的脂肪酸，但刺激了[U-14C]甘油进入酰基脂质。群集通量控制系数的计算表明，约 70%的代谢控制在脂质组装反应模块中。蒙特卡罗模拟估计了所得群集通量控制系数的误差，对于模块 A 为 0.27±0.06，对于模块 B 为 0.73±0.06。两种控制分析方法得出了非常相似的结果，表明在我们的条件下，模块 B 的反应更为重要。这与油棕或橄榄果实培养的数据形成鲜明对比，对于提高油菜籽脂质产量的努力非常重要。
