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

点击翻译按钮获取中文摘要

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.