Trawick J D, Wright R M, Poyton R O
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder 80309-0347.
J Biol Chem. 1989 Apr 25;264(12):7005-8.
The COX6 gene encodes subunit VI of cytochrome c oxidase. Previously, this gene and its mRNAs were characterized, and its expression has been shown to be subject to glucose repression/derepression. In this study we have examined the effects of heme and the HAP1 (CYP1) and HAP2 genes on the expression of COX6. By quantitating COX6 RNA levels and assaying beta-galactosidase activity in yeast cells carrying COX6-lacZ fusion genes, we have found that COX6 is regulated positively by heme and HAP2, but is unaffected by HAP1. Through 5' deletion analysis we have also found that the effects of heme and HAP2 on COX6 are mediated by sequences between 135 and 590 base pairs upstream of its initiation codon. These findings identify COX6 as the fourth respiratory protein gene that is known to be regulated positively by heme and HAP2. The other three, CYC1, COX4, and COX5a, encode iso-1-cytochrome c, cytochrome c oxidase subunit IV, and an isolog, Va, of cytochrome c oxidase subunit V, respectively. Thus, it appears that the biogenesis of two interacting proteins, cytochrome c and cytochrome c oxidase, in the mitochondrial respiratory chain, are under the control of common factors.
COX6基因编码细胞色素c氧化酶的亚基VI。此前，已对该基因及其mRNA进行了表征，并且其表达已显示受到葡萄糖阻遏/去阻遏的影响。在本研究中，我们研究了血红素以及HAP1（CYP1）和HAP2基因对COX6表达的影响。通过定量携带COX6 - lacZ融合基因的酵母细胞中的COX6 RNA水平并测定β-半乳糖苷酶活性，我们发现COX6受到血红素和HAP2的正向调控，但不受HAP1的影响。通过5'缺失分析，我们还发现血红素和HAP2对COX6的影响是由其起始密码子上游135至590个碱基对之间的序列介导的。这些发现确定COX6是已知受血红素和HAP2正向调控的第四个呼吸蛋白基因。另外三个基因，CYC1、COX4和COX5a，分别编码异-1-细胞色素c、细胞色素c氧化酶亚基IV以及细胞色素c氧化酶亚基V的一个异构体Va。因此，线粒体呼吸链中两种相互作用的蛋白质，细胞色素c和细胞色素c氧化酶的生物合成似乎受共同因子的控制。
