Novel mode of ligand binding by the SH2 domain of the human XLP disease gene product SAP/SH2D1A
Novel mode of ligand binding by the SH2 domain of the human XLP disease gene product SAP/SH2D1A
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DOI：
10.1016/s0960-9822(00)80080-9
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发表时间：
1999-12-02
期刊：
影响因子：
9.2
通讯作者：
Pawson, T
中科院分区：
文献类型：
--
作者：
Li, SC;Gish, G;Pawson, T
背景资料：胞质信号蛋白的蛋白质同源2（SH 2）结构域通常在羧基末端残基的背景下结合磷酸酪氨酸（pTyr）位点。SAP（也称为SH 2D 1A或DSHP）是在人类X连锁淋巴组织增生性（XLP）疾病中突变的基因的产物，其几乎仅包含单个SH 2结构域，其可以通过接合T细胞共激活因子如SLAM来调节T细胞信号传导，从而阻断含有SH 2结构域的其他信号传导蛋白的结合。SAP-SLAM相互作用可以以磷酸化非依赖性方式发生。为了表征SAP和SLAM之间的相互作用，我们合成了对应于SLAM中残基Y281处的SAP结合位点的肽。11个残基的SLAM肽的磷酸化和非磷酸化形式都结合SAP，解离常数分别为150 nM和330 nM。在氨基或羧基末端截短的SLAM磷酸肽以高亲和力结合至SAP，表明SAP SH 2结构域相对于pTyr残基识别氨基末端和羧基末端序列。这些结果得到了证实的核磁共振（NMR）研究N-15-和C-13-标记的SAP与三个SLAM肽复合：氨基端截短的磷酸肽，羧基端截短的磷酸肽和非磷酸化的Tyr-含有全长peptide.Conclusions：SAP SH 2结构域具有独特的特异性。它不仅以磷酸化非依赖性方式结合肽，还识别氨基末端残基之前或羧基末端残基之后的pTyr残基。我们建议，三个“叉”的肽配体（氨基和羧基末端和pTyr）可以从事SAP SH 2结构域，占其不寻常的性能。这些数据表明模块化蛋白质相互作用结构域的灵活性。
Background: The proteins homology 2 (SH2) domains of cytoplasmic signaling proteins generally bind phosphotyrosine (pTyr) sites in the context of carboxyterminal residues. SAP (also known as SH2D1A or DSHP), the product of the gene that is mutated in human X-linked lymphoproliferative (XLP) disease, comprises almost exclusively a single SH2 domain, which may modulate T-cell signaling by engaging T-cell co-activators such as SLAM, thereby blocking binding of other signaling proteins that contain SH2 domains, The SAP-SLAM interaction can occur in a phosphorylation-independent manner.Results: To characterize the interaction between SAP and SLAM, we synthesized peptides corresponding to the SAP-binding site at residue Y281 in SLAM. Both phosphorylated and non-phosphorylated versions of an 11-residue SLAM peptide bound SAP, with dissociation constants of 150 nM and 330 nM, respectively. SLAM phosphopeptides that were truncated either at the amino or carboxyl terminus bound with high affinity to SAP, suggesting that the SAP SH2 domain recognizes both amino-terminal and carboxy-terminal sequences relative to the pTyr residue. These results were confirmed by nuclear magnetic resonance (NMR) studies on N-15- and C-13-labeled SAP complexed with three SLAM peptides: an amino-terminally truncated phosphopeptide, a carboxy-terminally truncated phosphopeptide and a non-phosphorylated Tyr-containing full-length peptide.Conclusions: The SAP SH2 domain has a unique specificity. Not only does it bind peptides in a phosphorylation-independent manner, it also recognizes a pTyr residue either preceded by amino-terminal residues or followed by carboxy-terminal residues. We propose that the three 'prongs' of a peptide ligand (the amino and carboxyl termini and the pTyr) can engage the SAP SH2 domain, accounting for its unusual properties. These data point to the flexibility of modular protein-interaction domains.