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hnRNPA1 中的 RGG 盒特异性识别端粒 G-四链体 DNA,并增强 UP1 结构域的 G-四链体解链能力。

RGG-box in hnRNPA1 specifically recognizes the telomere G-quadruplex DNA and enhances the G-quadruplex unfolding ability of UP1 domain.

机构信息

Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560012, India.

NMR Research Centre, Indian Institute of Science, Bengaluru 560012, India.

出版信息

Nucleic Acids Res. 2018 Nov 2;46(19):10246-10261. doi: 10.1093/nar/gky854.

Abstract

hnRNPA1 is a member of heteronuclear ribonucleoproteins that has been shown to promote telomere elongation apart from its roles in RNA transport and alternative splicing. It is a modular protein with an N-terminal domain called UP1 that consists of two RNA Recognition Motifs (RRM1 and RRM2 domains) and a C-terminal region that harbors functional motifs such as RGG-box, a prion-like domain, and a nuclear shuttling sequence. UP1 has been reported to bind and destabilize telomeric DNA G-quadruplexes and thereby participate in DNA telomere remodeling. An RGG-box motif that consists of four RGG repeats (containing arginine and glycine residues) is located C-terminal to the UP1 domain and constitutes an additional nucleic acid and protein-binding domain. However, the precise role of the RGG-box of hnRNPA1 in telomere DNA recognition and G-quadruplex DNA unfolding remains unexplored. Here, we show that the isolated RGG-box interacts specifically with the structured telomere G-quadruplex DNA but not with the single-stranded DNA. Further the interaction of the RGG-box with the G-quadruplex DNA is dependent on the loop nucleotides of the G-quadruplex. Finally, we show that the RGG-box enhances the G-quadruplex unfolding activity of the adjacent UP1 domain. We propose that UP1 and RGG-box act synergistically to achieve complete telomere G-quadruplex DNA unfolding.

摘要

hnRNPA1 是核不均一核糖核蛋白的成员,它除了在 RNA 转运和选择性剪接中的作用外,还被证明可以促进端粒的延长。它是一种具有模块化结构的蛋白质,其 N 端结构域称为 UP1,由两个 RNA 识别基序(RRM1 和 RRM2 结构域)和一个 C 端区域组成,该区域包含功能基序,如 RGG 盒、类朊病毒结构域和核穿梭序列。已有报道称 UP1 可以结合并破坏端粒 DNA G-四链体,从而参与 DNA 端粒重塑。位于 UP1 结构域 C 端的 RGG 盒基序由四个 RGG 重复(包含精氨酸和甘氨酸残基)组成,构成了另一个核酸和蛋白质结合结构域。然而,hnRNPA1 的 RGG 盒在端粒 DNA 识别和 G-四链体 DNA 展开中的精确作用仍未被探索。在这里,我们表明分离的 RGG 盒与结构域化的端粒 G-四链体 DNA 特异性相互作用,但不与单链 DNA 相互作用。此外,RGG 盒与 G-四链体 DNA 的相互作用依赖于 G-四链体的环核苷酸。最后,我们表明 RGG 盒增强了相邻 UP1 结构域的 G-四链体展开活性。我们提出 UP1 和 RGG 盒协同作用以实现完整的端粒 G-四链体 DNA 展开。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/5ebc/6212785/16b335d09b0d/gky854fig1.jpg

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