Dynamic metabolic response of Aspergillus niger to glucose perturbation: evidence of regulatory mechanism for reduced glucoamylase production
Dynamic metabolic response of Aspergillus niger to glucose perturbation: evidence of regulatory mechanism for reduced glucoamylase production
复制标题
黑曲霉对葡萄糖扰动的动态代谢反应：减少葡糖淀粉酶产生的调节机制的证据
DOI：
10.1016/j.jbiotec.2018.08.005
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发表时间：
2018-12-10
影响因子：
4.1
通讯作者：
Xia, Jianye
中科院分区：
文献类型：
--
作者：
Li, Chao;Shu, Wei;Xia, Jianye
环境梯度是蛋白质生产放大过程中的一个重要问题。为探讨非均匀葡萄糖浓度对尼日尔曲霉生长的动态调控机制，对稳态条件下的黑曲霉进行了葡萄糖扰动实验。尼日尔恒化器培养物，并以秒的时间尺度跟踪中心碳代谢中细胞内代谢物的动态分布。上层糖酵解和磷酸戊糖途径在葡萄糖扰动后表现出急剧变化，而下层糖酵解、TCA循环和氨基酸库由于酶的变构调节和大库代谢产物的缓冲功能而表现出中度和延长的响应。葡萄糖-6-磷酸的提高显著增加了PP途径的代谢通量，不仅为蛋白质合成提供了更多的氧化还原辅因子（NADPH），而且为细胞生长提供了更多的前体物质（磷酸核糖焦磷酸和核糖-5-磷酸）。此外，总腺嘌呤核苷酸和主要前体氨基酸的减少表明RNA合成的上调是产生胁迫蛋白所必需的，并部分解释了当A.尼日尔经历了葡萄糖浓度波动的环境。这些发现将有助于从工程或遗传学角度改进生物反应器的操作、设计和放大。
Environmental gradient is an important common issue during scale-up process for protein production. To address the dynamic regulatory mechanism of Aspergillus niger being exposed to inhomogeneous glucose concentrations, glucose perturbation were experimented on the steady state of A. niger chemostat culture, and dynamic profiles of the intracellular metabolites in central carbon metabolism were tracked in a time scale of seconds. The upper glycolysis and pentose phosphate pathway showed sharp variations after glucose perturbation, while the lower glycolysis, TCA cycle and amino acid pools represented a moderate and prolonged response due to the allosteric regulation of enzymes and buffering function of metabolites with large pool sizes. Improved glucose-6-phosphate enhanced the metabolic flux to PP pathway remarkably, which provided not only more redox cofactors (NADPH) for protein synthesis but also more precursors (phosphoribosyl pyrophosphate and ribose-5-phosphate) for cell growth. Moreover, reduction of the total adenine nucleotides and major precursor amino acids indicated the upregulated RNA synthesis was required to produce stress proteins, and partially explained the drop of glucoamylase production when A. niger experienced a fluctuated glucose concentration environment. These findings would be valuable for improving bioreactor operation, design, and scaleup from engineering or genetic aspects.