Nargang F E, Bertrand H
Mol Gen Genet. 1978 Oct 25;166(1):15-23. doi: 10.1007/BF00379724.
Three nuclear mutants of Neurospora crassa, temperature-sensitive for the synthesis of cytochrome aa3 have been isolated. When grown at 41 degrees C the mutants have large amounts of KCN-insensitive respiration, reduced amounts of cytochrome aa3 and cytochrome c oxidase activity, and grow more slowly than wild-type cultures grown at the same temperature. When the mutants are grown at 23 degrees C, they are virtually indistinguishable from wild-type strains. The mutants were selected on the basis of their slow growth at 41 degrees C in medium containing salicylhydroxamic acid, and by their inability to reduce 2,3,5-triphenyltetrazolium chloride at 41 degrees c. The selecttion technique was designed to eliminate mutants that did not carry thermolabile electron transport chain components. However, studies on the thermolability of the cytochrome oxidase activity in isolated mitochondria indicate that the enzyme of the mutants is no more susceptible to heat denaturation than is the enzyme in wild-type mitochondria. This suggests that the synthesis or assembly of cytochrome aa3 may be altered in the mutants at the restrictive temperature.
已分离出粗糙脉孢菌的三个对细胞色素aa3合成温度敏感的核突变体。当在41℃下生长时，这些突变体具有大量对氰化钾不敏感的呼吸作用，细胞色素aa3和细胞色素c氧化酶活性降低，并且比在相同温度下生长的野生型培养物生长得更慢。当突变体在23℃下生长时，它们与野生型菌株几乎没有区别。这些突变体是基于它们在含有水杨羟肟酸的培养基中于41℃下生长缓慢，以及在41℃下不能还原2,3,5-三苯基氯化四氮唑而被筛选出来的。该筛选技术旨在排除不携带热不稳定电子传递链成分的突变体。然而，对分离线粒体中细胞色素氧化酶活性的热稳定性研究表明，突变体的酶与野生型线粒体中的酶相比，对热变性并不更敏感。这表明在限制温度下，突变体中细胞色素aa3的合成或组装可能发生了改变。
