Rapamycin sensitivity of the Schizosaccharomyces pombe tor2 mutant and organization of two highly phosphorylated TOR complexes by specific and common subunits
Rapamycin sensitivity of the Schizosaccharomyces pombe tor2 mutant and organization of two highly phosphorylated TOR complexes by specific and common subunits
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DOI：
10.1111/j.1365-2443.2007.01141.x
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发表时间：
2007-12-01
期刊：
影响因子：
2.1
通讯作者：
Yanagida, Mitsuhiro
中科院分区：
文献类型：
--
作者：
Hayashi, Takeshi;Hatanaka, Mitsuko;Yanagida, Mitsuhiro
营养物质是细胞生长和分裂所必需的。对裂糖菌温度敏感菌株的筛选分离出一个营养不敏感的突变体tor2-287。该突变体在富培养基中产生氮饥饿诱导的停滞表型，无法从停滞中恢复，并且对雷帕霉素过敏。靠近ATP腺嘌呤碱基的催化区域的L2048S取代突变是独特的，因为它是引起雷帕霉素过敏的唯一已知遗传原因。在营养细胞质中，Tor2的定位呈斑点状，在滞留细胞的细胞质中，Tor2的定位呈斑点状和膜状。通过质谱分析，我们确定了6个亚基（Tco89、Bit61、Toc1、Tel2、Tti1和Cka1），除了之前确定的6个亚基（Tor1、Tor2、Mip1/Raptor、Ste20/Rictor、Sin1/Avo1和Wat1/Lst8）外，它们还组成了TOR复合物（TORCs）。到目前为止检查的所有亚基都是多次磷酸化的。与Tti1结合的Tel2与多种磷脂酰肌醇激酶（PIK）相关的激酶相互作用，包括Tra1、Tra2和Rad3，以及Tor1和Tor2。因此，Schizosaccharomyces pombe torc应该在功能上是冗余的，并且可能通过两种torc共同或特定的不同亚基，甚至是各种pik相关激酶共同的亚基广泛调节。torc的功能冗余可以解释tor2-287对雷帕霉素的超敏反应。
Nutrients are essential for cell growth and division. Screening of Schizosaccharomyces pombe temperature-sensitive strains led to the isolation of a nutrient-insensitive mutant, tor2-287. This mutant produces a nitrogen starvation-induced arrest phenotype in rich media, fails to recover from the arrest, and is hypersensitive to rapamycin. The L2048S substitution mutation in the catalytic domain in close proximity to the adenine base of ATP is unique as it is the sole known genetic cause of rapamycin hypersensitivity. Localization of Tor2 was speckled in the vegetative cytoplasm, and both speckled and membranous in the arrested cell cytoplasm. Using mass spectroscopic analysis, we identified six subunits (Tco89, Bit61, Toc1, Tel2, Tti1 and Cka1) that, in addition to the six previously identified subunits (Tor1, Tor2, Mip1/Raptor, Ste20/Rictor, Sin1/Avo1 and Wat1/Lst8), comprise the TOR complexes (TORCs). All of the subunits so far examined are multiply phosphorylated. Tel2 bound to Tti1 interacts with various phosphatidyl inositol kinase (PIK)-related kinases including Tra1, Tra2 and Rad3, as well as Tor1 and Tor2. Schizosaccharomyces pombe TORCs should thus be functionally redundant and might be broadly regulated through different subunits that are either common or specific to the two TORCs, or even common to various PIK-related kinases. Functional redundancy of the TORCs may explain the rapamycin hypersensitivity of tor2-287.