A synthetic Pur-based peptide binds and alters G-quadruplex secondary structure present in the expanded RNA repeat of C9orf72 ALS/FTD.
A synthetic Pur-based peptide binds and alters G-quadruplex secondary structure present in the expanded RNA repeat of C9orf72 ALS/FTD.
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DOI：
10.1016/j.bbamcr.2020.118674
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发表时间：
2020-02
期刊：
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通讯作者：
M. Wortman;A. Dagdanova;Andrea M. Clark;E. Godfrey;S. Pascal;Edward M. Johnson;D. C. Daniel
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作者：
M. Wortman;A. Dagdanova;Andrea M. Clark;E. Godfrey;S. Pascal;Edward M. Johnson;D. C. Daniel
动物模型中 Pur-alpha (Pura) 蛋白水平的增加可缓解肌萎缩侧索硬化症/额颞叶痴呆 (ALS/FTD) 疾病谱的某些细胞症状。 Pura 是进化上保守的富含鸟嘌呤多核苷酸结合蛋白 Pur 家族的成员，含有 60-80 个氨基酸的重复特征 PUR 结构域。在这里，我们使用了一种合成肽 TZIP，与 Pur 结构域类似，但具有基于进化保守的 Pur 家族结合结构域的共识的序列改变，并具有添加的转运蛋白序列。 ALS/FTD 的一个主要家族形式 C9orf72(C9) 是由于 Pur 结合元件 (GGGGCC) 的六核苷酸重复扩增 (HRE) 所致。我们通过圆二色性证明，含有这种富含嘌呤序列的RNA寡核苷酸主要由平行的G-四链体组成。 TZIP 肽结合 DNA 和 RNA 中的该重复序列。它结合 RNA 元件，包括 G 四链体，与随机寡核苷酸相比具有高度特异性。此外，TZIP 结合线性和 G-四链体重复 RNA，形成更高阶的 G-四链体二级结构。这种基于 Pur 的肽的构象变化代表了调节 C9 重复序列内 G 四链体二级结构的新机制。 C9 RNA 结构构型的 TZIP 调节可能会改变复合物与其他蛋白质的相互作用。这种基于 Pur 的机制提供了新的治疗靶点，可能有助于解释 Pura 对 ALS/FTD 某些细胞病理学方面的缓解。
Increased Pur-alpha (Pura) protein levels in animal models alleviate certain cellular symptoms of the disease spectrum amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD). Pura is a member of the Pur family of evolutionarily conserved guanine-rich polynucleotide binding proteins containing a repeated signature PUR domain of 60–80 amino acids. Here we have employed a synthetic peptide, TZIP, similar to a Pur domain, but with sequence alterations based on a consensus of evolutionarily conserved Pur family binding domains and having an added transporter sequence. A major familial form of ALS/FTD,C9orf72(C9), is due to a hexanucleotide repeat expansion (HRE) of (GGGGCC), a Pur binding element. We show by circular dichroism that RNA oligonucleotides containing this purine-rich sequence consist largely of parallel G-quadruplexes. TZIP peptide binds this repeat sequence in both DNA and RNA. It binds the RNA element, including the G-quadruplexes, with a high degree of specificity versus a random oligonucleotide. In addition, TZIP binds both linear and G-quadruplex repeat RNA to form higher order G-quadruplex secondary structures. This change in conformational form by Pur-based peptide represents a new mechanism for regulating G quadruplex secondary structure within the C9 repeat. TZIP modulation of C9 RNA structural configuration may alter interaction of the complex with other proteins. This Pur-based mechanism provides new targets for therapy, and it may help to explain Pura alleviation of certain cellular pathological aspects of ALS/FTD.