Ashman W H, Barbuch R J, Ulbright C E, Jarrett H W, Bard M
Department of Biology, Indiana University-Purdue University, Indianapolis 46205.
Lipids. 1991 Aug;26(8):628-32. doi: 10.1007/BF02536427.
The yeast ERG2 gene codes for the C-8 sterol isomerase, an enzyme required for the isomerization of the delta 8 double bond to the delta 7 position in ergosterol biosynthesis. The ERG2 gene was cloned by complementation of a C-8 sterol isomerase mutant strain (erg2). The complementing region of DNA required to restore ergosterol synthesis to erg2 was limited to a 1.0 kb StuI-BglII fragment. In order to determine whether the ERG2 gene was essential for yeast viability, a LEU2 gene was inserted into the NdeI site (made blunt) of this 1.0 kb fragment. Transformation of a wild type diploid strain with the ERG2 substituted DNA resulted in the generation of viable haploids containing the erg2 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.
酵母ERG2基因编码C-8甾醇异构酶，该酶是麦角固醇生物合成过程中使δ8双键异构化为δ7位置所必需的。通过对C-8甾醇异构酶突变株（erg2）进行互补克隆得到了ERG2基因。将麦角固醇合成恢复到erg2所需的互补DNA区域被限制在一个1.0 kb的StuI-BglII片段。为了确定ERG2基因对酵母生存能力是否必不可少，将一个LEU2基因插入到这个1.0 kb片段的NdeI位点（处理成平端）。用ERG2替代DNA转化野生型二倍体菌株，产生了含有erg2无效等位基因（erg2-4::Leu2）的可存活单倍体。这些结果表明，C-8甾醇异构酶活性对酵母细胞生存能力不是必不可少的。这种破坏是该途径远端第二个被破坏而不影响细胞生存能力的麦角固醇生物合成基因。
