Specific sequences from the carboxyl terminus of human p53 gene product form anti-parallel tetramers in solution.
Specific sequences from the carboxyl terminus of human p53 gene product form anti-parallel tetramers in solution.
复制标题
来自人p53基因产物羧基末端的特定序列在溶液中形成反平行四聚体。
DOI：
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发表时间：
1994
影响因子：
11.1
通讯作者：
K. Sakaguchi
中科院分区：
文献类型：
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作者：
H. Sakamoto;M. Lewis;H. Kodama;E. Appella;K. Sakaguchi
人类P53是一种肿瘤抑制基因产物，与细胞周期控制和生长抑制有关，已知它在溶液中形成同源异构体。为了研究结构与四聚化的关系，化学合成了9个与人P53羧基末端序列相对应的多肽，并通过分析超速离心法测定了它们的平衡结合性质。通过圆二色谱测量确定的二级结构与每个肽的齐聚特性相关。多肽319-393和319-360的沉降谱符合多肽单体与多肽四聚体平衡的二态模型。319-360氨基和羧基末端残基的连续缺失减少了四聚体的形成。此外，丙氨酸替代Leu-323、Tyr-327和Leu-330取消了四聚反应。圆二色谱研究表明，319-351肽的α-螺旋含量最高，而其他未形成四聚体的多肽螺旋结构较低。这些研究定义了一个最小区域，并确定了参与四聚反应的某些关键残基。四聚体中单体单元之间的交联研究表明，螺旋采用反平行排列。我们认为，P53四聚化结构域螺旋结构的构象变化导致了亚基相对于彼此的重新定位。这种重新定位提供了一种解释，将羧基末端的构象变化与高度保守的中央结构域在序列特异性DNA结合中的变化联系起来。
Human p53 is a tumor-suppressor gene product associated with control of the cell cycle and with growth suppression, and it is known to form homotetramers in solution. To investigate the relationship of structure to tetramerization, nine peptides corresponding to carboxyl-terminal sequences in human p53 were chemically synthesized, and their equilibrium associative properties were determined by analytical ultracentrifugation. Secondary structure, as determined by circular dichroism measurements, was correlated with oligomerization properties of each peptide. The sedimentation profiles of peptides 319-393 and 319-360 fit a two-state model of peptide monomers in equilibrium with peptide tetramers. Successive deletion of amino- and carboxyl-terminal residues from 319-360 reduced tetramer formation. Further, substitution of alanine for Leu-323, Tyr-327, and Leu-330 abolished tetramerization. Circular dichroism studies showed that peptide 319-351 had the highest alpha-helix content, while the other peptides that did not form tetramers had low helical structure. These studies define a minimal region and identify certain critical residues involved in tetramerization. Cross-linking studies between monomer units in the tetramer suggest that the helices adopt an anti-parallel arrangement. We propose that conformational shifts in the helical structure of the p53 tetramerization domain result in a repositioning of subunits relative to one another. This repositioning provides an explanation relating conformational changes at the carboxyl terminus with changes in sequence-specific DNA binding by the highly conserved central domain.