McKercher Marissa A, Guan Xiaoyang, Tan Zhongping, Wuttke Deborah S
Department of Chemistry and Biochemistry, University of Colorado Boulder , Boulder, Colorado 80309, United States.
Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado Boulder , Boulder, Colorado 80309, United States.
Biochemistry. 2017 Apr 25;56(16):2225-2237. doi: 10.1021/acs.biochem.7b00023. Epub 2017 Apr 11.
SH2 domains recognize phosphotyrosine (pY)-containing peptide ligands and play key roles in the regulation of receptor tyrosine kinase pathways. Each SH2 domain has individualized specificity, encoded in the amino acids neighboring the pY, for defined targets that convey their distinct functions. The C-terminal SH2 domain (PLCC) of the phospholipase C-γ1 full-length protein (PLCγ1) typically binds peptides containing small and hydrophobic amino acids adjacent to the pY, including a peptide derived from platelet-derived growth factor receptor B (PDGFRB) and an intraprotein recognition site (Y783 of PLCγ1) involved in the regulation of the protein's lipase activity. Remarkably, PLCC also recognizes unexpected peptides containing amino acids with polar or bulky side chains that deviate from this pattern. This versatility in recognition specificity may allow PLCγ1 to participate in diverse, previously unrecognized, signaling pathways in response to binding chemically dissimilar partners. We have used structural approaches, including nuclear magnetic resonance and X-ray crystallography, to elucidate the mechanisms of noncognate peptide binding to PLCC by ligands derived from receptor tyrosine kinase ErbB2 and from the insulin receptor. The high-resolution peptide-bound structures reveal that PLCC has a relatively static backbone but contains a chemically rich protein surface comprised of a combination of hydrophobic pockets and amino acids with charged side chains. We demonstrate that this expansive and chemically diverse PLCC interface, in addition to peptide conformational plasticity, permits PLCC to recognize specific noncognate peptide ligands with multimodal specificity.
SH2结构域识别含磷酸酪氨酸（pY）的肽配体，并在受体酪氨酸激酶途径的调节中发挥关键作用。每个SH2结构域对特定靶点具有个性化的特异性，这种特异性由pY附近的氨基酸编码，这些靶点传达着它们独特的功能。磷脂酶C-γ1全长蛋白（PLCγ1）的C末端SH2结构域（PLCC）通常结合与pY相邻的含有小的疏水性氨基酸的肽，包括源自血小板衍生生长因子受体B（PDGFRB）的肽以及参与调节该蛋白脂肪酶活性的蛋白内识别位点（PLCγ1的Y783）。值得注意的是，PLCC还能识别含有偏离这种模式的极性或大体积侧链氨基酸的意外肽段。这种识别特异性的多功能性可能使PLCγ1能够参与多种先前未被认识的信号通路，以响应与化学性质不同的伴侣结合。我们使用了包括核磁共振和X射线晶体学在内的结构方法，来阐明源自受体酪氨酸激酶ErbB2和胰岛素受体的配体与PLCC结合非同源肽的机制。高分辨率的肽结合结构表明，PLCC具有相对静态的主链，但包含一个化学性质丰富的蛋白质表面，该表面由疏水口袋和带电荷侧链的氨基酸组合而成。我们证明，除了肽构象可塑性外，这个广阔且化学性质多样的PLCC界面还允许PLCC以多模式特异性识别特定的非同源肽配体。
