AbstractThe yeastERG2 gene codes for the C‐8 sterol isomerase, an enzyme required for the isomerization of the δ8 double bond to the δ7 position in ergosterol biosynthesis. TheERG2 gene was cloned by complementation of a C‐8 sterol isomerase mutant strain (erg2). The complementing region of DNA required to restore ergosterol synthesis toerg2 was limited to a 1.0 kbStuI‐BglII fragment. In order to determine whether theERG2 gene was essential for yeast viability, aLEU2 gene was inserted into theNdeI site (made blunt) of this 1.0 kb fragment. Transformation of a wild type diploid strain with theERG2 substituted DNA resulted in the generation of viable haploids containing theerg2 null allele (erg2–4∶∶Leu2). These results suggest that the C‐8 sterol isomerase activity is not essential for yeast cell viability. This disruption represents the second ergosterol biosynthetic gene in the distal portion of the pathway to be disrupted without adversely affecting cell viability.
摘要酵母ERG2基因编码C-8甾醇异构酶,这是麦角甾醇生物合成过程中δ8双键向δ7位置异构化所需的一种酶。ERG2基因是通过对C-8甾醇异构酶突变株(erg2)进行互补而克隆的。恢复 erg2 麦角甾醇合成所需的 DNA 互补区仅限于 1.0 kbStuI-BglII 片段。为了确定ERG2基因是否对酵母的活力至关重要,我们在这1.0 kb片段的NdeI位点(钝化)插入了一个LEU2基因。用取代ERG2基因的DNA转化野生型二倍体菌株,结果产生了含有ERG2无效等位基因(ERG2-4∶∶Leu2)的有活力的单倍体。这些结果表明,C-8甾醇异构酶活性对酵母细胞的活力并不重要。这种干扰是该途径远端部分的第二个麦角甾醇生物合成基因被干扰而不会对细胞活力产生不利影响。