Soto Aníbal, Carman George M
Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA.
J Biol Chem. 2008 Apr 11;283(15):10079-88. doi: 10.1074/jbc.M800502200. Epub 2008 Feb 14.
In the yeast Saccharomyces cerevisiae, the CKI1-encoded choline kinase catalyzes the committed step in the synthesis of phosphatidylcholine via the CDP-choline branch of the Kennedy pathway. Analysis of a P(CKI1)-lacZ reporter gene revealed that CKI1 expression was regulated by intracellular levels of the essential mineral zinc. Zinc depletion resulted in a concentration-dependent induction of CKI1 expression. This regulation was mediated by the zinc-sensing and zinc-inducible transcriptional activator Zap1p. A purified Zap1p probe interacted with two putative UAS(ZRE) sequences (ZRE1 and ZRE2) in the CKI1 promoter. Mutations of ZRE1 and ZRE2 to a nonconsensus UAS(ZRE) attenuated the induction of CKI1 expression in response to zinc depletion. A UAS(INO) element in the CKI1 promoter was responsible for stimulating CKI1 expression, but this element was not involved with the regulation by zinc depletion. The induction of CKI1 expression in zinc-depleted cells translated into increased choline kinase activity in vitro and in vivo, and an increase in phosphatidylcholine synthesis via the Kennedy pathway.
在酿酒酵母中，由CKI1编码的胆碱激酶通过肯尼迪途径的CDP - 胆碱分支催化磷脂酰胆碱合成的关键步骤。对P(CKI1)-lacZ报告基因的分析表明，CKI1的表达受必需矿物质锌的细胞内水平调控。锌缺乏导致CKI1表达呈浓度依赖性诱导。这种调控由锌感应和锌诱导的转录激活因子Zap1p介导。纯化的Zap1p探针与CKI1启动子中的两个假定的UAS(ZRE)序列（ZRE1和ZRE2）相互作用。将ZRE1和ZRE2突变为非一致性UAS(ZRE)会减弱对锌缺乏的CKI1表达诱导。CKI1启动子中的UAS(INO)元件负责刺激CKI1表达，但该元件与锌缺乏的调控无关。锌缺乏细胞中CKI1表达的诱导转化为体外和体内胆碱激酶活性的增加，以及通过肯尼迪途径的磷脂酰胆碱合成增加。
