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首页> 外文期刊>Molecular and Cellular Biology >Inverse regulation of the yeast COX5 genes by oxygen and heme.
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Inverse regulation of the yeast COX5 genes by oxygen and heme.

机译：氧气和血红素对酵母COX5基因的反调控。

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The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.
机译：COX5a和COX5b基因编码酵母细胞色素c氧化酶亚基V的不同形式。尽管两个基因的多肽产物在功能上是可互换的，但通常在酵母线粒体和细胞色素c氧化酶的制剂中发现的是Va亚基。我们在这里显示，亚基Va的优势部分源于两个基因对分子氧的存在的差异反应。我们的结果表明，在有氧生长期间，COX5a水平较高，而COX5b水平较低。厌氧地，图案反转了。 COX5a水平下降了七倍，而COX5b水平上升了七倍。氧似乎在通过血红素的转录水平上起作用，因为添加血红素可恢复需氧生长细胞的需氧转录模式，并且在血红素生物合成途径（hem1）中含有突变的菌株中再现了厌氧菌对COX5转录的影响。 ）。结合氧血红素反应，我们确定了ROX1基因的产物，这是由氧控制的几个酵母基因的反式调节因子，也参与了COX5的表达。这些结果，以及我们在某些酵母菌株中观察到COX5b表达的显着变化，表明COX5基因经历了复杂的调控模式。这种调节，特别是厌氧状态下COX5b水平的增加，可能反映了对改变环境条件而调节关键呼吸酶活性的尝试。这里介绍的结果以及其他实验室的结果表明，厌氧菌过程中某些代谢酶的诱导或抑制可能是酵母细胞中常见且重要的生理反应。

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