ANTIMYCIN-INSENSITIVE MUTANTS OF CANDIDA-UTILIS .2. EFFECTS OF ANTIMYCIN ON CYTOCHROME-B
ANTIMYCIN-INSENSITIVE MUTANTS OF CANDIDA-UTILIS .2. EFFECTS OF ANTIMYCIN ON CYTOCHROME-B
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DOI：
10.1016/0005-2728(75)90173-5
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发表时间：
1975-01-01
期刊：
影响因子：
--
通讯作者：
SLATER, EC
中科院分区：
文献类型：
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作者：
GRIMMELIKHUIJZEN, CJP;MARRES, CAM;SLATER, EC
1. Cytochromeb-562在突变体28的亚线粒体颗粒中比在野生型颗粒中在琥珀酸的有氧稳态呼吸期间减少得更多。当达到厌氧状态时，突变体细胞色素的减少先于快速的再氧化。在低浓度抗霉素存在下，在野生型中观察到类似的再氧化。与野生型相反，突变体中电子传递的抑制具有比对细胞色素b的影响高得多的抗霉素滴度（即，有氧稳态还原;底物、氰化物和氧存在下的还原;细胞色素b-562的“红移”和E ′ 0的降低）。此外，电子传递的滴定曲线是双曲线，而还原曲线是S形的。结果表明，无论是突变型还是野生型，抗霉素对电子传递和细胞色素的作用是可以分离的.突变体中的红移比野生型中的更广泛。细胞色素b-558和细胞色素b-566（在突变体和野生型中在564.5 nm处吸收）不同时响应于添加抗霉素，表明它们是两种独立的细胞色素。抗霉素对电子传递和细胞色素b还原的影响在完整细胞中也存在差异.提出了一种野生型呼吸链模型，其中（i）在非偶联系统中，细胞色素blie不在主要的电子传递链中，（ii）抗霉素诱导QH 2-细胞色素还原酶的构象变化，导致对细胞色素的影响，从而抑制电子传递，（iii）存在对抗生素具有低亲和力的第二个抗霉素结合位点，能够抑制电子传递。
1. Cytochromeb-562 is more reduced in submitochondrial particles of mutant 28 during the aerobic steady-state respiration with succinate than in particles of the wild type. When anaerobiosis is reached, the reduction of cytochromebis preceded by a rapid reoxidation in the mutant. A similar reoxidation is observed in the wild type in the presence of low concentrations of antimycin.2. In contrast to the wild type, inhibition of electron transport in the mutant has a much higher antimycin titre than effects on cytochromesb(viz., aerobic steadystate reduction; reduction in the presence of substrate, cyanide and oxygen; the ‘red shift’ and lowering ofE′0of cytochromeb-562). Moreover, the titration curve of electron transport is hyperbolic whereas the curves for the reduction are sigmoidal. The conclusion is, that in both mutant and wild type, the actions of antimycin on electron transport and cytochromesbare separable.3. The red shift in the mutant is more extensive than in the wild type.4. Cytochromeb-558 and cytochromeb-566 (that absorbs in mutant and wild type at 564.5 nm) do not respond simultaneously to addition of antimycin, indicating that they are two separate cytochromes.5. The difference between the effect of antimycin on electron transport and cytochromesbreduction is also found in intact cells of the mutant.6. A model is suggested for the wild-type respiratory chain in which (i) the cytochromesblie, in an uncoupled system, out of the main electron-transfer chain, (ii) antimycin induces a conformation change in QH2-cytochromecreductase resulting in effects on cytochromeband inhibition of electron transport, (iii) a second antimycinbinding site with low affinity to the antibiotic is present, capable of inhibiting electron transport.