Identification of beta-amyloid-binding sites on transthyretin
Identification of beta-amyloid-binding sites on transthyretin
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DOI：
10.1093/protein/gzs026
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发表时间：
2012-07-01
影响因子：
2.4
通讯作者：
Murphy, Regina M.
中科院分区：
文献类型：
--
作者：
Du, Jiali;Cho, Patricia Y.;Murphy, Regina M.
运甲状腺素蛋白 (TTR) 与阿尔茨海默病相关肽 β-淀粉样蛋白 (A) 结合，可防止 A 诱导的神经毒性。在这项工作中，探讨了 TTR 上与 A 结合相关的特定结构域。由源自 TTR 重叠序列的肽构建阵列。检测到 A 与 TIAALLSPYSYS（残基 106117）的强结合，对应于 TTR 内片上的 G 链。 A 与跨越残基 5983 的四个连续肽微弱结合，其中包括通过 E/F 螺旋和环的 E 链。为了进一步查明 TTR 上与 A 结合相关的特定残基，生成了九个丙氨酸突变体：I68A、I73A、K76A、L82A、I84A、S85A、L17A、T106A 和 L110A。仅在 L82A 和 L110A 中 A 结合受到显着抑制，表明 A 与 TTR 的结合是通过这些大的疏水性亮氨酸介导的。与 L17A 和 S85A 的结合显着高于与野生型 TTR 的结合。 L17A 中结合的增强被认为是由于内部 L110 位点的空间限制减少而引起的，因为这两个残基在天然蛋白质中是相邻的。 S85A突变导致TTR四聚体稳定性降低； A 结合增加被认为是四元稳定性降低的直接结果。
Transthyretin (TTR) binds to the Alzheimer-related peptide beta-amyloid (A), and may protect against A-induced neurotoxicity. In this work, the specific domains on TTR involved with binding to A were probed. An array was constructed of peptides derived from overlapping sequences from TTR. Strong binding of A to TIAALLSPYSYS (residues 106117) was detected, corresponding to strand G on the inner -sheet of TTR. A bound weakly to four contiguous peptides spanning residues 5983, which includes strand E through the E/F helix and loop. To further pinpoint specific residues on TTR involved with A binding, nine alanine mutants were generated: I68A, I73A, K76A, L82A, I84A, S85A, L17A, T106A and L110A. A binding was significantly inhibited only in L82A and L110A, indicating that A binding to TTR is mediated through these bulky hydrophobic leucines. A binding to L17A and S85A was significantly higher than to wild-type TTR. Enhancement of binding in L17A is postulated to arise from reduced steric restriction to the interior L110 site, since these two residues are adjacent in the native protein. The S85A mutation caused a reduction in TTR tetramer stability; increased A binding is postulated to be a direct consequence of the reduced quaternary stability.