Gerasimenko O G, Iurkevich V V
Biokhimiia. 1987 Nov;52(11):1887-97.
New thermosensitive mutants of the yeast Saccharomyces cerevisiae which block the secretion of periplasmic enzymes at restriction temperature have been obtained. These mutants accumulate active low molecular weight and mature invertase species in the cell; the buoyant density of the cells in a Percoll gradient is higher than that in the wild strain cells. The mutant cells transferred to permissive temperature (25 degrees C) in the absence of protein synthesis can secrete some amount of accumulated invertase. It was found that the secretory defects of conditional mutants do not affect the activity of cytoplasmic enzymes (e.g., alcohol dehydrogenase) or the level of total protein synthesis and glycosylation and do not induce non-specific disturbances in energy metabolism and plasma membrane functions at restriction temperature. Some strains of new secretory mutants revealed uncoupled defective secretion of periplasmic enzymes and intrinsic membrane proteins (proline permease). The possibility of branching of the secretory pathway for periplasmic enzymes and cytoplasmic membrane proteins is discussed.
已获得酿酒酵母的新型热敏突变体，这些突变体在限制温度下会阻断周质酶的分泌。这些突变体在细胞中积累活性低分子量和成熟的转化酶；在Percoll梯度中，突变体细胞的浮力密度高于野生型菌株细胞。在缺乏蛋白质合成的情况下转移到允许温度（25℃）的突变体细胞可以分泌一定量积累的转化酶。发现条件突变体的分泌缺陷不影响细胞质酶（如乙醇脱氢酶）的活性或总蛋白质合成和糖基化水平，并且在限制温度下不会诱导能量代谢和质膜功能的非特异性紊乱。一些新的分泌突变体菌株显示周质酶和内在膜蛋白（脯氨酸通透酶）的分泌缺陷解偶联。讨论了周质酶和细胞质膜蛋白分泌途径分支的可能性。
