The WD40-repeat protein CreC interacts with and stabilizes the deubiquitinating enzyme CreB in vivo in Aspergillus nidulans
The WD40-repeat protein CreC interacts with and stabilizes the deubiquitinating enzyme CreB in vivo in Aspergillus nidulans
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DOI：
10.1046/j.1365-2958.2002.02811.x
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发表时间：
2002-03-01
影响因子：
3.6
通讯作者：
Kelly, JM
中科院分区：
文献类型：
--
作者：
Lockington, RA;Kelly, JM
对构巢曲霉碳代谢物阻遏的遗传剖析已经鉴定出两个基因，creB和creC，当它们发生突变时，会影响许多基因在碳代谢物阻遏和去阻遏条件下的表达。creB基因编码一种有功能的去泛素化酶，creC基因编码一种包含五个WD40重复基序和一个富含脯氨酸区域的蛋白质。这些发现使得对涉及去泛素化的细胞开关进行体内分子分析成为可能。我们证明，CreB去泛素化酶的过表达可以部分弥补细胞中CreC WD40重复蛋白的缺失，但反之则不行，因此，CreB去泛素化酶在CreC WD40重复蛋白的下游起作用。我们通过免疫共沉淀实验证明，在碳代谢物阻遏和碳代谢物去阻遏条件下，CreB去泛素化酶和CreC WD40重复蛋白在体内相互作用。此外，我们表明，在没有碳代谢物阻遏的情况下，CreC WD40重复蛋白是防止CreB去泛素化酶被蛋白酶解所必需的。这是首次表明一种调节性去泛素化酶与另一种对该去泛素化酶的稳定性所必需的蛋白质相互作用的案例。
Genetic dissection of carbon catabolite repression in Aspergillus nidulans has identified two genes, creB and creC, which, when mutated, affect expression of many genes in both carbon catabolite repressing and derepressing conditions. The creB gene encodes a functional deubiquitinating enzyme and the creC gene encodes a protein that contains five WD40 repeat motifs, and a proline-rich region. These findings have allowed the in vivo molecular analysis of a cellular switch involving deubiquitination. We demonstrate that overexpression of the CreB deubiquitinating enzyme can partially compensate for a lack of the CreC WD40-repeat protein in the cell, but not vice versa and, thus, the CreB deubiquitinating enzyme acts downstream of the CreC WD40-repeat protein. We demonstrate using co-immunoprecipitation experiments that the CreB deubiquitinating enzyme and the CreC WD40-repeat protein interact in vivo in both carbon catabolite repressing and carbon catabolite derepressing conditions. Further, we show that the CreC WD40-repeat protein is required to prevent the proteolysis of the CreB deubiquitinating enzyme in the absence of carbon catabolite repression. This is the first case in which a regulatory deubiquitinating enzyme has been shown to interact with another protein that is required for the stability of the deubiquitinating enzyme.