Studies on cyanide-resistant respiration

1)交替氧化酶在异常汉逊酵母线粒体中构成了一条抗氰化物的呼吸途径。这种酶的核编码基因的表达受不同条件的高度调控。克隆了异型棘豆的基因组DNA，并对其进行了分析。在上游区检测到类UAS2元件。凝胶迁移率改变分析也表明该元件可能参与了对基因表达的碳源依赖的调节。2)在异型棘球藻中，交替氧化酶的基因表达受QI位点抑制剂和SH化合物的诱导。当细胞被吡硫酮、锌离子载体和螯合剂EDTA等预处理时，加入抗霉素A后，交替氧化酶mRNA的表达完全被抑制。加入锌离子后，观察到mRNA水平的恢复。因此，锌离子参与了交替氧化酶基因的表达机制。3)锥虫交替氧化酶是细长的非洲锥虫呼吸链的唯一末端氧化酶。克隆了布氏锥虫氧化物酶基因，并在大肠杆菌中进行了表达。该酶在大肠杆菌中的功能表达表明，抗生素阿司可呋喃酮能特异性地抑制锥虫体内替代氧化酶的泛喹酚氧化位点。

1) Alternative oxidase constitutes a cyanide-resistant reapiratory pathway in the mitochondria of the yeast Hansenula anomala. The expression of nuclear-encoded gene of this enzyme is highly regulated depending upon the various conditions. The genomic DNA was cloned from H. anomala and analyzed. In the upstream region, UAS2-like element was detected. The gel mobility shift assay also suggests the possible involvement of this element in the carbon source-dependent regulation of the gene expression.2) The gene expression of alternative oxidase is induced by Qi site inhibitors and SH compounds in H. anomala. When the cells were pre-treated with pyrithione, zinc ionophore, and chelator, such as EDTA, the expression of alternative oxidase mRNA upon the addition of antimycin A was completely suppressed. The recovery ofmRNA level was observed by the addition of zinc ions. Accordingly, zinc ion is suggested to be involved in the expression machinery of alternative oxidase gene.3) Trypanosome alternative oxidase is the sole terminal oxidase of the respiratory chain of long slender bloodstream forms of African trypanosomes. A cDNA encoding the oxidase from Trypanosoma brucei brucei was cloned and expressed in Escherichia coli. The functional expression of the oxidase in E. coli indicates that the antibiotic, ascofuranone, specifically inhibits the ubiquinol oxidation site of trypanosome alternative oxidase.