The N-end rule pathway is required for import of histidine in yeast lacking the kinesin-like protein Cin8p.
The N-end rule pathway is required for import of histidine in yeast lacking the kinesin-like protein Cin8p.
复制标题
在缺乏驱动蛋白样蛋白 Cin8p 的酵母中，组氨酸的输入需要 N 端规则途径。
DOI：
10.1007/s002940050480
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发表时间：
1999
期刊：
影响因子：
2.5
通讯作者：
Varshavsky,A
中科院分区：
文献类型：
--
作者：
Xie,Y;Varshavsky,A
N-末端规则通路是一个泛素依赖的蛋白分解系统，其靶标包括含有不稳定N-末端残基的蛋白质。我们对需要N-端规则通路的酿酒酵母突变株进行了合成致死筛选。这样鉴定的突变株termedsln2在没有Ubr1p的情况下不能生长，Ubr1p是N-端规则途径的识别成分，而Ubr1p对亲本菌株在相同条件下的生存不是必不可少的。进一步的分析表明，S1n2ubr1Δ细胞的丧失活力可以被HIS3基因(亲本菌株中缺失)或培养液中高浓度的组氨酸拯救。这种组氨酸摄取缺陷由突变体ln2在没有Ubr1p存在的情况下表现出来，可追溯到编码组氨酸转运蛋白的基因HIP1。与sLn2 ubr1或sLn2 ubr1Δ细胞相比，hIP1在sLn2 ubr1Δ细胞中低表达。Ln2突变体的另一个特性是在37 °C下不能存活，这是UBR1或HIS3都不能挽救的。SLn2的这一特征使得SLn2的克隆成为可能，该基因被发现是一个被称为CIN8的基因，编码一种激动素样蛋白。因此，对于组氨酸导入INS的活性维持率而言，必须存在N端规则通路或Cin8p。组氨酸的啤酒营养缺乏症。我们考虑了这种先前未被怀疑的运动蛋白、泛素依赖的蛋白分解和组氨酸输入之间的联系的可能机制。
The N-end rule pathway is a ubiquitin-dependent proteolytic system whose targets include proteins bearing destabilizing N-terminal residues. We carried out a synthetic lethal screen forSaccharomyces cerevisiaemutants that require the N-end rule pathway for cell viability. A mutant thus identified, termedsln2, could not grow in the absence of Ubr1p, the recognition component of the N-end rule pathway, which was not essential for viability of the parental strain under the same conditions. Further analysis showed that inviability ofsln2ubr1Δ cells could be rescued either by theHIS3gene (which was absent from the parental strain) or by a high concentration of histidine in the medium. This defect in histidine uptake, exhibited by thesln2mutant in the absence but not in the presence of Ubr1p, was traced to the geneHIP1, which encodes the histidine transporter.HIP1was underexpressed insln2 ubr1Δ cells, in comparison to eithersln2 UBR1orSLN2 ubr1Δ cells. Yet another property of thesln2mutant was its inviability at 37 °C, which could not be rescued by eitherUBR1orHIS3. This feature ofsln2allowed the cloning ofSLN2, which was found to be a gene calledCIN8, encoding a kinesin-like protein. Thus, either the N-end rule pathway or Cin8p must be present for the viability-sustaining rate of histidine import inS. cerevisiaeauxotrophic for histidine. We consider possible mechanisms of this previously unsuspected link between kinesins, ubiquitin-dependent proteolysis, and the import of histidine.