Lombardo A, Cereghino G P, Scheffler I E
Department of Biology, University of California, San Diego, La Jolla 92093-0322.
Mol Cell Biol. 1992 Jul;12(7):2941-8. doi: 10.1128/mcb.12.7.2941-2948.1992.
We have examined the expression of the gene encoding the iron-protein subunit (Ip) of succinate dehydrogenase in Saccharomyces cerevisiae. The gene had been cloned by us and shown to be subject to glucose regulation (A. Lombardo, K. Carine, and I. E. Scheffler, J. Biol. Chem. 265:10419-10423, 1990). We discovered that a significant part of the regulation of the Ip mRNA levels by glucose involves the regulation of the turnover rate of this mRNA. In the presence of glucose, the half-life appears to be less than 5 min, while in glycerol medium, the half-life is greater than 60 min. The gene is also regulated transcriptionally by glucose. The upstream promoter sequence appeared to have four regulatory elements with consensus sequences shown to be responsible for the interaction with the HAP2/3/4 regulatory complex. A deletion analysis has shown that the two distal elements are redundant. These measurements were carried out by Northern (RNA) analyses of Ip mRNA transcripts as well as by assays of beta-galactosidase activity in cells carrying constructs of the Ip promoter linked to the lacZ coding sequence. These observations on the regulation of mRNA stability were also extended to the mRNA of the flavoprotein subunit of succinate dehydrogenase and in some experiments of iso-1-cytochrome c.
我们研究了酿酒酵母中琥珀酸脱氢酶铁蛋白亚基（Ip）编码基因的表达。该基因已由我们克隆，并显示受葡萄糖调控（A. 隆巴多、K. 卡琳和I. E. 谢弗勒，《生物化学杂志》265:10419 - 10423，1990年）。我们发现，葡萄糖对Ip mRNA水平的调控很大一部分涉及该mRNA周转率的调控。在葡萄糖存在的情况下，半衰期似乎小于5分钟，而在甘油培养基中，半衰期大于60分钟。该基因也受葡萄糖的转录调控。上游启动子序列似乎有四个调控元件，其共有序列显示负责与HAP2/3/4调控复合体相互作用。缺失分析表明，两个远端元件是多余的。这些测量通过对Ip mRNA转录本的Northern（RNA）分析以及对携带与lacZ编码序列相连的Ip启动子构建体的细胞中β-半乳糖苷酶活性的测定来进行。关于mRNA稳定性调控的这些观察结果也扩展到了琥珀酸脱氢酶黄素蛋白亚基的mRNA，并且在一些异-1-细胞色素c实验中也得到了验证。
