Yang Z, Bisson L F
Department of Viticulture and Enology, University of California, Davis 95616-8749, USA.
Yeast. 1996 Nov;12(14):1407-19. doi: 10.1002/(SICI)1097-0061(199611)12:14%3C1407::AID-YEA36%3E3.0.CO;2-1.
Saccharomyces cerevisiae strains carrying snf3 are defective in high affinity glucose transport, and thus are unable to grow fermentatively on media with low concentrations of glucose. A multicopy suppressor of the snf3 growth defect, SKS1 (suppressor kinase of snf3), was found to encode a putative ser/thr protein kinase homologous to Ran1p, a kinase that regulates the switch between meiosis and vegetative growth in Schizosaccharomyces pombe. Overexpression of the SKS1 open reading frame is sufficient for suppression of the growth defects of snf3 mutants. Disruption of the open reading frame eliminates this suppression; as does the mutation of the consensus ATP binding site of Sks1p. A DDSE (DNA dependent snf3 suppressor element) was found to be present in the SKS1 promoter region. The suppression by this DDSE occurs in the absence of SKS1 coding region, that is, the DDSE can suppress a snf3 sks1 double null mutant which fails to grow fermentatively on low glucose as a snf3 mutant does. Both SKS1 and its DDSE can additionally suppress the growth defects of grr1 mutants, which are also impaired in high affinity glucose transport. The snf3 genomic suppressors, rgt1, RGT2 and ssn6, are also capable of suppressing snf3 associated growth defects in a strain lacking sks1.
携带snf3的酿酒酵母菌株在高亲和力葡萄糖转运方面存在缺陷，因此无法在低浓度葡萄糖培养基上进行发酵生长。发现snf3生长缺陷的多拷贝抑制子SKS1（snf3的抑制激酶）编码一种假定的丝氨酸/苏氨酸蛋白激酶，与粟酒裂殖酵母中调节减数分裂和营养生长之间转换的激酶Ran1p同源。SKS1开放阅读框的过表达足以抑制snf3突变体的生长缺陷。开放阅读框的破坏消除了这种抑制作用；Sks1p共有ATP结合位点的突变也会消除这种抑制作用。发现SKS1启动子区域存在一个DDSE（DNA依赖性snf3抑制元件）。这种DDSE的抑制作用在没有SKS1编码区的情况下也会发生，也就是说，DDSE可以抑制snf3 sks1双缺失突变体，该突变体在低葡萄糖条件下不能像snf3突变体那样进行发酵生长。SKS1及其DDSE还可以额外抑制grr1突变体的生长缺陷，grr1突变体在高亲和力葡萄糖转运方面也存在缺陷。snf3基因组抑制子rgt1、RGT2和ssn6也能够在缺乏sks1的菌株中抑制与snf3相关的生长缺陷。
