Induction mechanism of cyanide-resistant respiration in the yeast, Hansenula anomala

一种抗生素，抗坏血氯胺，以某种方式作用于细胞色素bc_1复合物。这种抗生素在减少Cyt方面表现出与Qo位点抑制剂相似的效果。b_<560>，而抗坏血氯诱导核编码的替代氧化酶基因的表达，类似于抗霉素A，Qi位点抑制剂。钙离子载体和膜渗透性钙螯合剂抑制抗霉素A_<3->、二硫苏糖醇和抗坏血氯依赖诱导的替代氧化酶。半胱氨酸特异性修饰剂对诱导有较强的抑制作用，二硫苏糖醇对修饰有保护作用。这些结果提示细胞内Ca^<2+>、特定巯基、蛋白磷酸化和去磷酸化参与了向细胞核表达替代氧化酶基因的信号传导机制。2)我们已经克隆了汉氏菌（Hansenula anomalala）替代氧化酶的基因组克隆。在转录起始位点的上游区域，发现了一个类似uas2的序列。该序列被认为是控制碳源调控的替代氧化酶基因的表达。3)一种名为ascofuranone的抗生素可特异性抑制布鲁氏锥虫细长血流形式中线粒体电子传递系统中的泛醌氧化还原机制。此外，ascofuranone与甘油联合有效地抑制了寄生虫的体外生长。在小鼠体内，乙酰呋喃酮与甘油联用有很强的杀锥虫活性。我们的结果强烈表明，ascofuranone可能是非洲锥虫病化疗药物的一个有希望的候选人。

1) An antibiotic, ascochlorin, somehow acts on the cytochrome bc_1 complex. This antibiotic exhibited similar effects to those by Qo site inhibitors, on the reduction of Cyt.b_<560> by succinate, whereas ascochlorin induced the expression of nuclear-encoded alternative oxidase gene, similarly to antimycin A,Qi site inhibitors. Ca ionophores and membrane permeable Ca chelating agents inhibited the antimycin A_<3->, dithiothreitol-, and ascochlorin-dependent induction of alternative oxidase. Cysteine-specific modifying reagents strongly inhibited the induction and dithiothreitol exhibited protective effects on the modification. The induction was sensitive to staurosporine and calyculin A.These results suggest that intracellular Ca^<2+>, certain sulfhydryl group (s), protein phosphorylation, and dephosphorylation are involved in the signaling mechanism toward nuclei to express the alternative oxidase gene.2) We have cloned genomic clones encoding alternative oxidase from Hansenula anomala. In the upstream region from the transcription start site, a UAS2-like sequence was found. This sequence is suggested to control the alternative oxidase gene expression regulated by carbon source in this organism.3) An antibiotic, ascofuranone, specifically inhibits the ubiquinone redox machinery in the mitochondrial electron transport system in the long slender bloodstream forms of Trypanosoma brucei brucei. Futher, ascofuranone in combination with glycerol potently inhibited the in vitro growth of the parasite. The in vivo trypanocidal activity of ascofuranone in combination with glycerol was very powerful in mice. Our results strongly suggest that ascofuranone may be a promising candidate for the chemotherapeutic agents of African trypanosomiasis.