Martins Vicente P, Soriani Frederico M, Magnani Taisa, Tudella Valéria G, Goldman Gustavo H, Curti Carlos, Uyemura Sérgio A
Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.
J Bioenerg Biomembr. 2008 Aug;40(4):297-305. doi: 10.1007/s10863-008-9163-9. Epub 2008 Sep 17.
Differences between the respiratory chain of the fungus Paracoccidioides brasiliensis and its mammalian host are reported. Respiration, membrane potential, and oxidative phosphorylation in mitochondria from P. brasiliensis spheroplasts were evaluated in situ, and the presence of a complete (Complex I-V) functional respiratory chain was demonstrated. In succinate-energized mitochondria, ADP induced a transition from resting to phosphorylating respiration. The presence of an alternative NADH-ubiquinone oxidoreductase was indicated by: (i) the ability to oxidize exogenous NADH and (ii) the lack of sensitivity to rotenone and presence of sensitivity to flavone. Malate/NAD(+)-supported respiration suggested the presence of either a mitochondrial pyridine transporter or a glyoxylate pathway contributing to NADH and/or succinate production. Partial sensitivity of NADH/succinate-supported respiration to antimycin A and cyanide, as well as sensitivity to benzohydroxamic acids, suggested the presence of an alternative oxidase in the yeast form of the fungus. An increase in activity and gene expression of the alternative NADH dehydrogenase throughout the yeast's exponential growth phase was observed. This increase was coupled with a decrease in Complex I activity and gene expression of its subunit 6. These results support the existence of alternative respiratory chain pathways in addition to Complex I, as well as the utilization of NADH-linked substrates by P. brasiliensis. These specific components of the respiratory chain could be useful for further research and development of pharmacological agents against the fungus.
报道了巴西副球孢子菌呼吸链与其哺乳动物宿主之间的差异。对巴西副球孢子菌原生质体线粒体中的呼吸、膜电位和氧化磷酸化进行了原位评估，并证明存在完整的（复合体I-V）功能性呼吸链。在琥珀酸供能的线粒体中，ADP诱导了从静息呼吸到磷酸化呼吸的转变。以下证据表明存在一种替代的NADH-泛醌氧化还原酶：（i）氧化外源NADH的能力，以及（ii）对鱼藤酮不敏感且对黄酮敏感。苹果酸/NAD(+)支持的呼吸表明存在线粒体吡啶转运体或乙醛酸途径，有助于NADH和/或琥珀酸的产生。NADH/琥珀酸支持的呼吸对抗霉素A和氰化物部分敏感，以及对苯并异羟肟酸敏感，表明该真菌酵母形式中存在替代氧化酶。在酵母的指数生长期观察到替代NADH脱氢酶的活性和基因表达增加。这种增加与复合体I活性及其亚基6的基因表达减少相关。这些结果支持除复合体I外还存在替代呼吸链途径，以及巴西副球孢子菌利用NADH连接底物的观点。呼吸链的这些特定成分可能有助于针对该真菌的药物制剂的进一步研发。
