Effect of different NADH oxidase levels on glucose metabolism by Lactococcus lactis:: Kinetics of intracellular metabolite pools determined by in vivo nuclear magnetic resonance
Effect of different NADH oxidase levels on glucose metabolism by Lactococcus lactis:: Kinetics of intracellular metabolite pools determined by in vivo nuclear magnetic resonance
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DOI：
10.1128/aem.68.12.6332-6342.2002
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发表时间：
2002-12-01
影响因子：
4.4
通讯作者：
Santos, H
中科院分区：
文献类型：
--
作者：
Neves, AR;Ramos, A;Santos, H
以3株产H2O型NADH氧化酶活性不同的乳酸乳球菌（Lactococcus lactis）为材料，研究了氧对葡萄糖代谢的影响。乳酸菌MG 1363、编码形成H2O的NADH氧化酶的基因缺失的NOX-菌株和NADH氧化酶活性增强约100倍的NOX+菌株。通过使用C-13核磁共振在体内获得代谢事件的全面描述。结果表明：（1）在有氧条件下，果糖1，6-二磷酸[Fru（1，6）P-2]的水平低于厌氧条件下的水平，且Fru（1，6）P-2的消耗速率很高;（ii）在有氧条件下，3-磷酸甘油酸和磷酸烯醇丙酮酸的水平显著提高，而在NOx-拉紧;和（iii）糖酵解通量在饱和氧水平的存在下降低，但在响应于NADH氧化酶活性的变化时不改变。特别地，观察到糖酵解通量在NOX+菌株中没有增强，表明糖酵解通量主要不是由细胞中的NADH水平决定的。最终产品的模式是相同的NOX-和亲本菌株;在，NOX+菌株的碳通量被转移到生产的α-乙酰乳酸衍生的化合物，并在低pH值下，该菌株产生的双乙酰浓度高达1.6 mM。的数据进行了整合的目标，确定在氧气的存在下，葡萄糖代谢的主要监管方面。
Three isogenic strains of Lactococcus lactis with different levels of H2O-forming NADH oxidase activity were used to study the effect of oxygen on glucose metabolism: the parent strain L. lactis MG1363, a NOX- strain harboring a deletion of the gene coding for H2O-forming NADH oxidase, and a NOX+ strain with the NADH oxidase activity enhanced by about 100-fold. A comprehensive description of the metabolic events was obtained by using C-13 nuclear magnetic resonance in vivo. The most noticeable results of this study are as follows: (i) under aerobic conditions the level of fructose 1,6-bisphosphate [Fru(1,6)P-2] was lower than the level under anaerobic conditions, and the rate of Fru(1,6)P-2 depletion was ' very high; (ii) the levels of 3-phosphoglycerate and phosphoenolpyruvate were considerably enhanced under aerobic conditions and significantly lower in the NOX- strain; and (iii) the glycolytic flux decreased in the presence of saturating levels of oxygen, but it was not altered in response to changes in the NADH oxidase activity. In particular, the observation that the glycolytic flux was not enhanced in the NOX+ strain indicated that glycolytic flux was not primarily determined by the level of NADH in the cell. The patterns of end products were identical for the NOX- and parent strains; in, the NOX+ strain the carbon flux was diverted to the production of alpha-acetolactate-derived compounds, and at a low pH this strain produced diacetyl at concentrations up to 1.6 mM. The data were integrated with the goal of identifying the main regulatory aspects of glucose metabolism in the presence of oxygen.