An unexpected 2-histidine phosphoesterase activity of suppressor of T-cell receptor signaling protein 1 contributes to the suppression of cell signaling.
An unexpected 2-histidine phosphoesterase activity of suppressor of T-cell receptor signaling protein 1 contributes to the suppression of cell signaling.
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T 细胞受体信号蛋白 1 抑制剂具有意想不到的 2-组氨酸磷酸酯酶活性，有助于抑制细胞信号传导。
DOI：
10.1074/jbc.ra120.013482
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Carpino,Nick
中科院分区：
文献类型：
--
作者：
Yin,Yue;Frank,David;Zhou,Weijie;Kaur,Neena;French,JarrodB;Carpino,Nick
T细胞受体（TCR）信号传导（Sts）抑制蛋白Sts-1和Sts-2抑制各种免疫细胞中受体介导的信号传导途径，包括T细胞中的TCR途径和吞噬细胞中的Dectin-1信号传导途径。作为多结构域酶，它们含有N-末端泛素缔合结构域、中心Src同源3结构域和C-末端组氨酸磷酸酶结构域。最近，2-组氨酸（2 H）磷酸酯酶基序内的N-末端部分的Sts。2 H磷酸酯酶基序定义了存在于几种酶中的进化上古老的蛋白质结构域，所述酶水解不同底物（包括环核苷酸）上的环状磷酸键。其特征在于两个不变的组氨酸残基在催化活性中起关键作用。与其作为磷酸酯酶的归属一致，我们在这里证明Sts-1 2 H磷酸酯酶结构域对二核苷酸2′，3 ′-环NADP显示催化的、可饱和的磷酸二酯酶活性。该酶表现出高度的底物特异性，并选择性地产生3′-核苷酸作为唯一产物。Sts-1对3′端含有2′，3 ′-环磷酸基团的5-mer RNA寡核苷酸也具有磷酸二酯酶催化活性。为了研究Sts-1 2 H磷酸酯酶活性的功能意义，我们产生了组氨酸-丙氨酸变体，并检查了它们负调节细胞信号传导途径的能力。保守组氨酸的取代损害Sts-1抑制TCR和Dectin-1受体下游信号通路的能力。我们的研究结果确定了一个迄今未知的细胞酶活性与Sts-1，并表明这种催化活性与特定的细胞信号转导结果。
The suppressor of T-cell receptor (TCR) signaling (Sts) proteins Sts-1 and Sts-2 suppress receptor-mediated signaling pathways in various immune cells, including the TCR pathway in T cells and the Dectin-1 signaling pathway in phagocytes. As multidomain enzymes, they contain an N-terminal ubiquitin-association domain, a central Src homology 3 domain, and a C-terminal histidine phosphatase domain. Recently, a 2-histidine (2H) phosphoesterase motif was identified within the N-terminal portion of Sts. The 2H phosphoesterase motif defines an evolutionarily ancient protein domain present in several enzymes that hydrolyze cyclic phosphate bonds on different substrates, including cyclic nucleotides. It is characterized by two invariant histidine residues that play a critical role in catalytic activity. Consistent with its assignment as a phosphoesterase, we demonstrate here that the Sts-1 2H phosphoesterase domain displays catalytic, saturable phosphodiesterase activity toward the dinucleotide 2′,3′-cyclic NADP. The enzyme exhibited a high degree of substrate specificity and selectively generated the 3′-nucleotide as the sole product. Sts-1 also had phosphodiesterase catalytic activity toward a 5-mer RNA oligonucleotide containing a 2′,3′-cyclic phosphate group at its 3′ terminus. To investigate the functional significance of Sts-1 2H phosphoesterase activity, we generated His-to-Ala variants and examined their ability to negatively regulate cellular signaling pathways. Substitution of either conserved histidine compromised the ability of Sts-1 to suppress signaling pathways downstream of both the TCR and the Dectin-1 receptor. Our results identify a heretofore unknown cellular enzyme activity associated with Sts-1 and indicate that this catalytic activity is linked to specific cell-signaling outcomes.