Superstructural self-assembly of the G-quadruplex structure formed by the homopurine strand in a DNA tract of human telomerase gene promoter

2008 ◽  
Vol 136 (2-3) ◽  
pp. 159-163 ◽  
Author(s):  
Sabrina Pisano ◽  
Michela Varra ◽  
Emanuela Micheli ◽  
Teresa Coppola ◽  
Pasquale De Santis ◽  
...  
Keyword(s):  
Self Assembly ◽  
Gene Promoter ◽  
Quadruplex Structure ◽  
G Quadruplex ◽  
Human Telomerase

scholarly journals A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution

2020 ◽  
Author(s):  
Bishnu P. Paudel ◽  
Aaron Lavel Moye ◽  
Hala Abou Assi ◽  
Roberto El-Khoury ◽  
Scott B. Cohen ◽  
...  
Keyword(s):  
Single Molecule ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Quadruplex Structure ◽  
G Quadruplex ◽  
Nucleotide Addition ◽  
Small Molecule Ligands ◽  
Large Conformational Change ◽  
Human Telomerase ◽  
Linear Product

AbstractTelomeric G-quadruplexes (G4) were long believed to form a protective structure at telomeres, preventing their extension by the ribonucleoprotein telomerase. Contrary to this belief, we have previously demonstrated that parallel-stranded conformations of telomeric G4 can be extended by human and ciliate telomerase. However, a mechanistic understanding of the interaction of telomerase with structured DNA remained elusive. Here, we use single-molecule fluorescence resonance energy transfer (smFRET) microscopy and bulk-phase enzymology to propose a mechanism for the resolution and extension of parallel G4 by telomerase. Binding is initiated by the RNA template of telomerase interacting with the G-quadruplex; nucleotide addition then proceeds to the end of the RNA template. It is only through the large conformational change of translocation following synthesis that the G-quadruplex structure is completely unfolded to a linear product. Surprisingly, parallel G4 stabilization with either small molecule ligands or by chemical modification does not always inhibit G4 unfolding and extension by telomerase. These data reveal that telomerase is a parallel G-quadruplex resolvase.

scholarly journals A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Bishnu P Paudel ◽  
Aaron Lavel Moye ◽  
Hala Abou Assi ◽  
Roberto El-Khoury ◽  
Scott B Cohen ◽  
...  
Keyword(s):  
Single Molecule ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Quadruplex Structure ◽  
G Quadruplex ◽  
Nucleotide Addition ◽  
Small Molecule Ligands ◽  
Large Conformational Change ◽  
Human Telomerase ◽  
Linear Product

Telomeric G-quadruplexes (G4) were long believed to form a protective structure at telomeres, preventing their extension by the ribonucleoprotein telomerase. Contrary to this belief, we have previously demonstrated that parallel-stranded conformations of telomeric G4 can be extended by human and ciliate telomerase. However, a mechanistic understanding of the interaction of telomerase with structured DNA remained elusive. Here, we use single-molecule fluorescence resonance energy transfer (smFRET) microscopy and bulk-phase enzymology to propose a mechanism for the resolution and extension of parallel G4 by telomerase. Binding is initiated by the RNA template of telomerase interacting with the G-quadruplex; nucleotide addition then proceeds to the end of the RNA template. It is only through the large conformational change of translocation following synthesis that the G-quadruplex structure is completely unfolded to a linear product. Surprisingly, parallel G4 stabilization with either small molecule ligands or by chemical modification does not always inhibit G4 unfolding and extension by telomerase. These data reveal that telomerase is a parallel G-quadruplex resolvase.

scholarly journals Up-Regulating Relaxin Expression by G-Quadruplex Interactive Ligand to Achieve Antifibrotic Action

Endocrinology ◽  
2012 ◽  
Vol 153 (8) ◽  
pp. 3692-3700 ◽  
Author(s):  
Hui-Ping Gu ◽  
Sen Lin ◽  
Ming Xu ◽  
Hai-Yi Yu ◽  
Xiao-Jun Du ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Cardiac Fibrosis ◽  
Cardiac Fibroblasts ◽  
Heart Diseases ◽  
Gene Promoter ◽  
Binding Motif ◽  
Endogenous Expression ◽  
G Quadruplex

Myocardial fibrosis is a key pathological change in a variety of heart diseases contributing to the development of heart failure, arrhythmias, and sudden death. Recent studies have shown that relaxin prevents and reverses cardiac fibrosis. Endogenous expression of relaxin was elevated in the setting of heart disease; the extent of such up-regulation, however, is insufficient to exert compensatory actions, and the mechanism regulating relaxin expression is poorly defined. In the rat relaxin-1 (RLN1, Chr1) gene promoter region we found presence of repeated guanine (G)-rich sequences, which allowed formation and stabilization of G-quadruplexes with the addition of a G-quadruplex interactive ligand berberine. The G-rich sequences and the G-quadruplexes were localized adjacent to the binding motif of signal transducer and activator of transcription (STAT)3, which negatively regulates relaxin expression. Thus, we hypothesized that the formation and stabilization of G-quadruplexes by berberine could influence relaxin expression. We found that berberine-induced formation of G-quadruplexes did increase relaxin gene expression measured at mRNA and protein levels. Formation of G-quadruplexes significantly reduced STAT3 binding to the promoter of relaxin gene. This was associated with consequent increase in the binding of RNA polymerase II and STAT5a to relaxin gene promoter. In cardiac fibroblasts and rats treated with angiotensin II, berberine was found to suppress fibroblast activation, collagen synthesis, and extent of cardiac fibrosis through up-regulating relaxin. The antifibrotic action of berberine in vitro and in vivo was similar to that by exogenous relaxin. Our findings document a novel therapeutic strategy for fibrosis through up-regulating expression of endogenous relaxin.

Design and Synthesis of an Expanded Porphyrin That Has Selectivity for the c-MYC G-Quadruplex Structure

2005 ◽  
Vol 127 (9) ◽  
pp. 2944-2959 ◽  
Author(s):  
Jeyaprakashnarayanan Seenisamy ◽  
Sridevi Bashyam ◽  
Vijay Gokhale ◽  
Hariprasad Vankayalapati ◽  
Daekyu Sun ◽  
...  
Keyword(s):  
Design And Synthesis ◽  
Quadruplex Structure ◽  
G Quadruplex ◽  
Expanded Porphyrin

Lab in a tube: a fast-assembled colorimetric sensor for highly sensitive detection of oligonucleotides based on a hybridization chain reaction

RSC Advances ◽  
2015 ◽  
Vol 5 (55) ◽  
pp. 44714-44721 ◽  
Author(s):  
Siqi Zhang ◽  
Kun Wang ◽  
Zhenyu Li ◽  
Zhongmin Feng ◽  
Ting Sun
Keyword(s):  
Complex Formation ◽  
Dna Sequence ◽  
Self Assembly ◽  
The Self ◽  
Hybridization Chain Reaction ◽  
Chain Reaction ◽  
Highly Sensitive ◽  
G Quadruplex ◽  
Colored Product ◽  
Highly Sensitive Detection

Upon adding THBV, the self-assembly of THBV with H1 allows the rest of the DNA sequence of H1 to accelerate H1–H2 complex formation. The G-quadruplex at the end of the H1–H2 complex could catalyze TMB into a colored product.

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