Studies on a proteinase B mutant of yeast.
Studies on a proteinase B mutant of yeast.
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酵母蛋白酶 B 突变体的研究。
DOI：
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
C. Ehmann
中科院分区：
文献类型：
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作者：
D. Wolf;C. Ehmann
已经分离出缺乏蛋白酶B活性的酵母突变体[Wolf，D. H.和Ehmann，C. 04 The Dog of the Woman（1978）92，121- 124]。这些突变体之一（HP 232）的特点是详细。通过检查分离的突变体液泡中的蛋白酶B活性来证实液泡定位酶的缺失。蛋白酶B活性缺陷在减数分裂四分体中以2：2分离。该突变被证明是隐性的。突变蛋白酶B活性不仅对合成底物不存在。Azocoll，还能对抗前几丁质合成酶、胞质苹果酸脱氢酶和果糖-1，6-二磷酸酶的生理底物。该突变体表现出正常的营养生长，这一现象与蛋白酶B可能是体内几丁质合成酶酶原的激活原理的想法不一致。荧光显微镜显示正常几丁质插入。野生型细胞中碳分解代谢物失活的基础酶（提出可能由蛋白酶B触发的机制），如细胞质苹果酸脱氢酶、果糖-1，6-二磷酸酶、磷酸烯醇丙酮酸羧激酶和异柠檬酸裂解酶，在突变体中也失活。NADP依赖的谷氨酸脱氢酶，这是发现失活的葡萄糖饥饿的野生型细胞，在突变体中正常进行。突变细胞在饥饿条件下显示出超过40%的蛋白质降解减少。与纯合野生型二倍体或突变基因杂合的二倍体相比，蛋白酶B缺失纯合的孢子化二倍体也表现出约40%的蛋白质降解减少。与纯合野生型二倍体或突变基因杂合的二倍体相比，蛋白酶B缺乏纯合的二倍体细胞的第一个子囊孢子出现的时间延迟约50%，孢子形成频率降低至约相同的程度。
Yeast mutant lacking proteinase B activity have been isolated [Wolf, D. H. and Ehmann, C. (1978) FEBS Lett. 92, 121--124]. One of these mutants (HP232) is characterized in detail. Absence of the vacuolar localized enzyme is confirmed by checking for proteinase B activity in isolated mutant vacuoles. Defective proteinase B activity segregates 2:2 in meiotic tetrads. The mutation is shown to be recessive. Mutant proteinase B activity is not only absent against the synthetic substrate. Azocoll, but also against the physiological substrate pre-chitin synthetase, cytoplasmic malate dehydrogenase and fructose-1,6-bisphosphatase. The mutant shows normal vegetative growth, a phenomenon not consistent with the idea that proteinase B might be the activating principle of chitin synthetase zymogen in vivo. Fluorescence microscopy shows normal chitin insertion. Enzymes underlying carbon-catabolite inactivation in wild-type cells (a mechanism proposed to be possibly triggered by proteinase B) such as cytoplasmic malate dehydrogenase, fructose-1,6-bisphosphatase, phosphoenolpyruvate carboxykinase and isocitrate lyase, are inactivated also in the mutant. NADP-dependent glutamate dehydrogenase, which is found to be inactivated in glucose-starved wild-type cells, proceeds normally in the mutant. Mutant cells show more than 40% reduced protein degradation under starvation conditions. Sporulating diploids, homozygous for proteinase B absence, also exhibit an approximately 40% reduced protein degradation as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene. The time of the appearance of the first ascospores of diploid cells, homozygous for proteinase B deficiency, is delayed about 50% and sporulation frequency is reduced to about the same extent as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene.