Quinn Jeanette M, Kropat Janette, Merchant Sabeeha
Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California 90095-1569, USA.
Eukaryot Cell. 2003 Oct;2(5):995-1002. doi: 10.1128/EC.2.5.995-1002.2003.
The Cpx1 and Cyc6 genes of Chlamydomonas reinhardtii are activated in copper-deficient cells via a signal transduction pathway that requires copper response elements (CuREs) and a copper response regulator defined by the CRR1 locus. The two genes can also be activated by provision of nickel or cobalt ions in the medium. The response to nickel ions requires at least one CuRE and also CRR1 function, suggesting that nickel interferes with a component in the nutritional copper signal transduction pathway. Nickel does not act by preventing copper uptake/utilization because (i) holoplastocyanin formation is unaffected in Ni(2+)-treated cells and (ii) provision of excess copper cannot reverse the Ni-dependent activation of the target genes. The CuRE is sufficient for conferring Ni-responsive expression to a reporter gene, which suggests that the system has practical application as a vehicle for inducible gene expression. The inducer can be removed either by replacing the medium or by chelating the inducer with excess EDTA, either of which treatments reverses the activation of the target genes.
莱茵衣藻的Cpx1和Cyc6基因在缺铜细胞中通过一条信号转导途径被激活，该途径需要铜反应元件（CuREs）和由CRR1位点定义的铜反应调节因子。这两个基因也可通过在培养基中提供镍离子或钴离子而被激活。对镍离子的反应至少需要一个CuRE以及CRR1的功能，这表明镍干扰了营养性铜信号转导途径中的一个成分。镍并非通过阻止铜的摄取/利用来发挥作用，因为（i）在镍离子处理的细胞中质体蓝素的形成不受影响，且（ii）提供过量铜不能逆转镍依赖的靶基因激活。CuRE足以赋予报告基因镍响应性表达，这表明该系统作为诱导型基因表达的载体具有实际应用价值。通过更换培养基或用过量EDTA螯合诱导剂均可去除诱导剂，这两种处理方式均可逆转靶基因的激活。
