Effects of overproduction of the catalytic domain of 3-hydroxy-3-methylglutaryl coenzyme A reductase on squalene synthesis in Saccharomyces cerevisiae
Effects of overproduction of the catalytic domain of 3-hydroxy-3-methylglutaryl coenzyme A reductase on squalene synthesis in Saccharomyces cerevisiae
复制标题
DOI：
10.1128/aem.63.9.3341-3344.1997
复制
发表时间：
1997-09-01
影响因子：
4.4
通讯作者：
Fritz, IB
中科院分区：
文献类型：
--
作者：
Donald, KAG;Hampton, RY;Fritz, IB
3-羟基-3-甲基戊二酰辅酶A（HMG-CoA）还原酶（HMG-R）是包括酵母在内的许多生物体中甲羟戊酸途径的主要限速酶。在酿酒酵母（Saccharomycescerevisiae）中，存在HMG-R的两种同工酶（Hmg 1 p和Hmg 2 p）。两者都由锚定跨膜结构域和催化结构域组成。我们已经通过过量生产Hmg 1 p的催化结构域去除了HMG-R的已知控制特征。这种过度生产导致角鲨烯生产的增强，这意味着HMG-R已被解除管制。在半厌氧和好氧条件下，这种增强作用是明显的。尽管角鲨烯产量增加，但过量生产HMG-R的酵母产生的麦角固醇的量没有增加。该结果表明在角鲨烯和麦角固醇形成之间存在另一个调节步骤。过量产生HMG-R催化结构域的细胞产生的角鲨烯水平估计高达野生型细胞产生的角鲨烯水平的10倍。角鲨烯产量的增加与生长率的下降相吻合。这种减少可能是途径的高浓度角鲨烯和前角鲨烯中间体积累的直接结果。
The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMG-R) is the major rate-limiting enzyme of the mevalonate pathway in many organisms, including yeasts. In the yeast Saccharomyces cerevisiae, there are two isoenzymes of HMG-R (Hmg1p and Hmg2p). Both consist of an anchoring transmembrane domain and a catalytic domain. We have removed the known controlling features of HMG-R by overproducing the catalytic domain of Hmg1p. This overproduction leads to an enhancement of squalene production, implying that HMG-R has been deregulated. The enhancement is apparent under semianaerobic and aerobic conditions. Despite the increase in squalene production, the amount of ergosterol produced by the HMG-R-overproducing yeast was not increased. This result suggests the presence of another regulatory step between squalene and ergosterol formation. Squalene levels generated by cells overproducing the catalytic domain of HMG-R were estimated to be up to 10 times those produced by wild-type cells. The enhancement in squalene production coincided with a reduction in growth rate. This reduction may be a direct consequence of the buildup of high concentrations of squalene and presqualene intermediates of the pathway.