The solution structure of the FATC domain of the protein kinase target of rapamycin suggests a role for redox-dependent structural and cellular stability
The solution structure of the FATC domain of the protein kinase target of rapamycin suggests a role for redox-dependent structural and cellular stability
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DOI：
10.1074/jbc.m501116200
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发表时间：
2005-05-27
影响因子：
4.8
通讯作者：
Grzesiek, S
中科院分区：
文献类型：
--
作者：
Dames, SA;Mulet, JM;Grzesiek, S
雷帕霉素（TOR）的靶标是一种高度保守的丝氨酸/苏氨酸激酶，在细胞生长的控制中起着核心作用。TOR具有典型的多域结构。只有激酶结构域具有催化功能；其他结构域被认为介导与TOR底物和调节因子的相互作用。除了雷帕霉素结合结构域外，TOR没有高分辨率的结构数据。在这里，我们提出了极其保守的cooh末端FATC结构域的结构，生物物理和诱变研究。这一领域对于TOR功能的重要性已在一些出版物中得到强调。我们发现，氧化形式的FATC结构域呈现出一种新的结构基序，由两个完全保守的半胱氨酸残基之间的α -螺旋和cooh末端二硫键环组成。减少后，环路区域的柔韧性显著增加。结构数据、二硫桥氧化还原电位和半胱氨酸到丝氨酸突变体的生化数据表明，细胞内氧化还原电位可以通过FATC结构域影响TOR蛋白的细胞数量。由于TOR mRNA的数量没有改变，因此FATC二硫键的氧化还原状态可能影响了TOR的降解。
The target of rapamycin ( TOR) is a highly conserved Ser/Thr kinase that plays a central role in the control of cellular growth. TOR has a characteristic multidomain structure. Only the kinase domain has catalytic function; the other domains are assumed to mediate interactions with TOR substrates and regulators. Except for the rapamycin-binding domain, there are no high-resolution structural data available for TOR. Here, we present a structural, biophysical, and mutagenesis study of the extremely conserved COOH-terminal FATC domain. The importance of this domain for TOR function has been highlighted in several publications. We show that the FATC domain, in its oxidized form, exhibits a novel structural motif consisting of an alpha-helix and a COOH-terminal disulfide-bonded loop between two completely conserved cysteine residues. Upon reduction, the flexibility of the loop region increases dramatically. The structural data, the redox potential of the disulfide bridge, and the biochemical data of a cysteine to serine mutant indicate that the intracellular redox potential can affect the cellular amount of the TOR protein via the FATC domain. Because the amount of TOR mRNA is not changed, the redox state of the FATC disulfide bond is probably influencing the degradation of TOR.