López-Mirabal H Reynaldo, Winther Jakob R, Kielland-Brandt Morten C
Carlsberg Laboratory, Copenhagen Valby, Denmark.
Biosci Biotechnol Biochem. 2007 Dec;71(12):2934-42. doi: 10.1271/bbb.70323. Epub 2007 Dec 7.
The conditional ero1-1 mutant, deficient in the ER-localized PDI oxidase Ero1p, is blocked in disulfide bond formation under restrictive conditions, such as high temperature, lack of oxygen, or high concentrations of membrane-permeant thiols. Previous studies of the physiological consequences of the ero1-1 mutation were carried out in a leu2 mutant. The ero1-1 leu2 strain does not grow in standard synthetic complete medium at 30 degrees C, a defect that can be remedied by increasing the L-leucine concentration in the medium or by transforming the ero1-1 leu2 strain with the LEU2 wild-type allele. In addition, the LEU2 gene can partially complement the growth impairment at 37 degrees C of the ero1-1 leu2 mutant. The leucine transporter Bap2p exhibits a dramatic decrease in stability in an ero1-1 strain, which may account for the pronounced leucine demand observed in the ero1-1 leu2 mutant.
条件性ero1-1突变体缺乏内质网定位的蛋白二硫键异构酶氧化酶Ero1p，在高温、缺氧或高浓度膜通透性硫醇等限制条件下，其二硫键形成受阻。先前对ero1-1突变体生理后果的研究是在leu2突变体中进行的。ero1-1 leu2菌株在30℃的标准合成完全培养基中无法生长，通过增加培养基中L-亮氨酸的浓度或用LEU2野生型等位基因转化ero1-1 leu2菌株，可弥补这一缺陷。此外，LEU2基因可部分弥补ero1-1 leu2突变体在37℃时的生长缺陷。亮氨酸转运蛋白Bap2p在ero1-1菌株中的稳定性显著降低，这可能解释了ero1-1 leu2突变体中观察到的明显亮氨酸需求。
