Casalone E, Barberio C, Cavalieri D, Polsinelli M
Dipartimento di Scienze Biomediche, Università di Chieti, via dei Vestini, I-66100 Chieti, Italy.
Yeast. 2000 Apr;16(6):539-45. doi: 10.1002/(SICI)1097-0061(200004)16:6<539::AID-YEA547>3.0.CO;2-K.
The function of the open reading frame (ORF) YOR108w of Saccharomyces cerevisiae has been analysed. The deletion of this ORF from chromosome XV did not give an identifiable phenotype. A mutant in which both ORF YOR108w and LEU4 gene have been deleted proved to be leucine auxotrophic and alpha-isopropylmalate synthase (alpha-IPMS)-negative. This mutant recovered alpha-IPMS activity and a Leu(+) phenotype when transformed with a plasmid copy of YOR108w. These data and the sequence homology indicated that YOR108w is the structural gene for alpha-IPMS II, responsible for the residual alpha-IPMS activity found in a leu4Delta strain. The leu4Delta strain appeared to be very sensitive to the leucine analogue trifluoroleucine. In the absence of leucine, its growth was not much impaired in glucose but more on non-fermentable carbon sources.
对酿酒酵母开放阅读框（ORF）YOR108w的功能进行了分析。从第十五号染色体上删除该ORF未产生可识别的表型。一个同时缺失ORF YOR108w和LEU4基因的突变体被证明是亮氨酸营养缺陷型且α-异丙基苹果酸合酶（α-IPMS）阴性。当用YOR108w的质粒拷贝转化该突变体时，其恢复了α-IPMS活性和亮氨酸原养型（Leu(+)）表型。这些数据以及序列同源性表明，YOR108w是α-IPMS II的结构基因，负责在leu4Δ菌株中发现的残余α-IPMS活性。leu4Δ菌株似乎对亮氨酸类似物三氟亮氨酸非常敏感。在缺乏亮氨酸的情况下，其在葡萄糖中的生长受影响不大，但在非发酵碳源上的生长受影响更大。
