Subtopic Deep Dive

G-Quadruplex Structure and Stability
Research Guide

What is G-Quadruplex Structure and Stability?

G-quadruplexes are four-stranded DNA structures formed by stacks of G-tetrads from guanine-rich sequences, with stability influenced by topology, loop motifs, and cations like K+.

Researchers use NMR, X-ray crystallography, and CD spectroscopy to characterize intramolecular and intermolecular G4 topologies. Computational models predict thermal stability modulated by cations and loops. Over 10 key papers from 2005-2016, led by Burge et al. (2006, 2357 citations) and Kypr et al. (2009, 1719 citations), define sequence motifs and structures.

Curated Papers

Key Challenges

Why It Matters

G4 structures in telomeres and promoters regulate telomerase and gene expression, enabling ligand design for cancer therapy (Rhodes and Lipps, 2015; Huppert and Balasubramanian, 2006). Human telomeric G4s adopt hybrid topologies in K+ solution, stabilizing against telomerase (Ambrus et al., 2006). Promoter G4s offer targets for selective stabilization, impacting oncology (Patel et al., 2007).

Key Research Challenges

Topology Diversity Prediction

G4s form parallel, antiparallel, and hybrid topologies depending on loops and sequence context, complicating prediction (Burge et al., 2006). NMR and crystallography reveal varied scaffolds, but computational models struggle with accuracy (Luu et al., 2006). Over 20 motifs identified in human genome require better tools (Todd, 2005).

Cation-Dependent Stability

K+ stabilizes telomeric G4s more than Na+, affecting folding pathways measurable by CD (Kypr et al., 2009). Thermal stability varies with ion type and concentration, challenging in vivo relevance (Ambrus et al., 2006). Models need refinement for physiological conditions (Bedrat et al., 2016).

Loop Motif Variability

Loops between G-tracts dictate polymorphism and ligand binding, with prevalence in promoters (Huppert and Balasubramanian, 2006). Characterizing motif impacts requires high-resolution methods like X-ray (Patel et al., 2007). Systematic analysis reveals non-random patterns (Todd, 2005).

Essential Papers

Quadruplex DNA: sequence, topology and structure

Sarah Burge, Gary N. Parkinson, Pascale Hazel et al. · 2006 · Nucleic Acids Research · 2.4K citations

G-quadruplexes are higher-order DNA and RNA structures formed from G-rich sequences that are built around tetrads of hydrogen-bonded guanine bases. Potential quadruplex sequences have been identifi...

Circular dichroism and conformational polymorphism of DNA

Jaroslav Kypr, Iva Kejnovská, Daniel Renčiuk et al. · 2009 · Nucleic Acids Research · 1.7K citations

Here we review studies that provided important information about conformational properties of DNA using circular dichroic (CD) spectroscopy. The conformational properties include the B-family of st...

G-quadruplexes and their regulatory roles in biology

Daniela Rhodes, Hans J. Lipps · 2015 · Nucleic Acids Research · 1.5K citations

'If G-quadruplexes form so readily in vitro, Nature will have found a way of using them in vivo' (Statement by Aaron Klug over 30 years ago).During the last decade, four-stranded helical structures...

G-quadruplexes in promoters throughout the human genome

J Huppert, Shankar Balasubramanian · 2006 · Nucleic Acids Research · 1.3K citations

Certain G-rich DNA sequences readily form four-stranded structures called G-quadruplexes. These sequence motifs are located in telomeres as a repeated unit, and elsewhere in the genome, where their...

Human telomeric sequence forms a hybrid-type intramolecular G-quadruplex structure with mixed parallel/antiparallel strands in potassium solution

Attila Ambrus, D. Chen, Jixun Dai et al. · 2006 · Nucleic Acids Research · 1.1K citations

Human telomeric DNA consists of tandem repeats of the sequence d(TTAGGG). The formation and stabilization of DNA G-quadruplexes in the human telomeric sequence have been shown to inhibit the activi...

Nanomaterials Based on DNA

Nadrian C. Seeman · 2010 · Annual Review of Biochemistry · 986 citations

The combination of synthetic stable branched DNA and sticky-ended cohesion has led to the development of structural DNA nanotechnology over the past 30 years. The basis of this enterprise is that i...

Highly prevalent putative quadruplex sequence motifs in human DNA

Alan K. Todd · 2005 · Nucleic Acids Research · 960 citations

We report here the results of a systematic search for the existence and prevalence of potential intramolecular G-quadruplex forming sequences in the human genome. We have also examined the tendency...

Reading Guide

Foundational Papers

Start with Burge et al. (2006) for sequence/topology overview (2357 citations), then Kypr et al. (2009) for CD methods (1719 citations), and Ambrus et al. (2006) for telomeric hybrid structure.

Recent Advances

Bedrat et al. (2016) re-evaluates G4 propensity with G4Hunter (673 citations); Rhodes and Lipps (2015) details regulatory roles (1471 citations).

Core Methods

CD spectroscopy for polymorphism (Kypr et al., 2009); NMR/crystallography for atomic models (Luu et al., 2006; Patel et al., 2007); G4Hunter for sequence prediction (Bedrat et al., 2016).

How PapersFlow Helps You Research G-Quadruplex Structure and Stability

Discover & Search

Research Agent uses searchPapers and exaSearch to find G4 topology papers, revealing Burge et al. (2006) as top-cited via citationGraph. findSimilarPapers expands from Rhodes and Lipps (2015) to promoter studies like Huppert and Balasubramanian (2006).

Analyze & Verify

Analysis Agent applies readPaperContent to extract CD spectra data from Kypr et al. (2009), then runPythonAnalysis with NumPy to plot melting curves and verify stability predictions via statistical fits. verifyResponse (CoVe) cross-checks claims against Ambrus et al. (2006), with GRADE scoring evidence strength for K+-induced folding.

Synthesize & Write

Synthesis Agent detects gaps in loop motif coverage across papers, flagging underexplored hybrid topologies. Writing Agent uses latexEditText to draft structural descriptions, latexSyncCitations for Burge et al. (2006), and latexCompile for figures; exportMermaid visualizes G-tetrad stacking diagrams.

Use Cases

"Analyze thermal stability of human telomeric G4 in K+ vs Na+ from key papers"

Research Agent → searchPapers('telomeric G-quadruplex stability K+') → Analysis Agent → readPaperContent(Ambrus et al. 2006) + runPythonAnalysis (pandas curve fitting on Tm data) → researcher gets verified melting temperature comparison plot.

"Write LaTeX review section on G4 topologies with citations"

Synthesis Agent → gap detection on Burge et al. (2006) topologies → Writing Agent → latexEditText('topology description') → latexSyncCitations → latexCompile → researcher gets compiled PDF section with telomere hybrid structure figure.

"Find code for G4Hunter algorithm from recent papers"

Research Agent → paperExtractUrls(Bedrat et al. 2016) → paperFindGithubRepo → githubRepoInspect → researcher gets Python script for G4 propensity scoring with usage examples.

Automated Workflows

Deep Research workflow scans 50+ G4 papers via searchPapers → citationGraph → structured report on topology evolution from Burge et al. (2006) to Bedrat et al. (2016). DeepScan applies 7-step CoVe to verify cation effects in Kypr et al. (2009) CD data with runPythonAnalysis checkpoints. Theorizer generates hypotheses on loop-ligand interactions from Patel et al. (2007).

Try Doxa for G-Quadruplex Structure and Stability Research

Frequently Asked Questions

What defines a G-quadruplex structure?

G-quadruplexes form from G-rich sequences stacking Hoogsteen-bonded G-tetrads, stabilized by monovalent cations (Burge et al., 2006).

What methods characterize G4 stability?

CD spectroscopy detects polymorphism, NMR/X-ray resolve topologies, and computational tools predict cation effects (Kypr et al., 2009; Ambrus et al., 2006).

What are key papers on G4 structures?

Burge et al. (2006, 2357 citations) reviews topology; Luu et al. (2006, 805 citations) details (3+1) telomeric scaffold; Rhodes and Lipps (2015, 1471 citations) covers biology.

What open problems exist in G4 research?

Predicting in vivo formation, quantifying loop motif effects on stability, and designing selective ligands remain challenges (Bedrat et al., 2016; Patel et al., 2007).