GO:1990955 G-rich single-stranded DNA binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1990955 (G-rich single-stranded DNA binding) is a molecular function defined as binding to G-rich, single-stranded DNA.
• This activity is central to telomere biology, where G-rich single-stranded overhangs are bound by shelterin components such as POT1 and by CST-Polα/primase.
• G-rich single-stranded DNA can fold into G-quadruplex structures, and binding proteins can modulate these conformations.
• Proteins that bind G-rich single-stranded DNA include POT1, CST complex subunits, CNBP, and plant telomere-binding proteins.
• Dysregulation of G-rich single-stranded DNA binding is linked to cancer, premature aging, and genome instability.
• CRISPR-based knockout, point mutation, knock-in, and overexpression models enable functional dissection of G-rich single-stranded DNA binding proteins.
Description
G-rich single-stranded DNA binding (GO:1990955) is a molecular function that describes the selective interaction of a protein with single-stranded DNA sequences rich in guanine residues. This activity is fundamental to processes that require transient or stable unwinding of G-rich DNA tracts, most notably at telomeres where the G-rich strand forms a 3' overhang. The binding event can protect the single-stranded DNA from degradation, regulate its accessibility to enzymes such as telomerase or DNA polymerase alpha/primase, or facilitate higher-order folding into G-quadruplex structures. Researchers study this function to understand how cells maintain chromosome ends, respond to replication stress, and avoid genomic instability. Because G-rich single-stranded DNA is a feature of many regulatory regions beyond telomeres, including promoters and recombination hotspots, the proteins that bind it are increasingly recognized as broad genome caretakers. This article integrates the QuickGO definition with verified PubMed literature to provide a research-grade overview of the mechanism, key genes, disease links, and experimental models for GO:1990955.
G-rich single-stranded DNA binding At A Glance
| GO ID | GO:1990955 |
|---|---|
| GO term | G-rich single-stranded DNA binding |
| Ontology | molecular_function |
| Synonym | None |
| Definition | Binding to G-rich, single-stranded DNA. |
| Major function | Selective recognition of single-stranded DNA sequences rich in guanine, often at telomeres or regulatory regions. |
| Related processes | Telomere maintenance, G-quadruplex regulation, DNA replication and repair. |
| Example proteins | POT1, CST complex subunits (CTC1, STN1, TEN1), CNBP, and plant telomere-binding proteins. |
| Disease relevance | Cancer, dyskeratosis congenita, and other telomere-related disorders. |
What Is GO:1990955?
According to the Gene Ontology, GO:1990955 is defined as binding to G-rich, single-stranded DNA. In other words, it is the molecular function of a protein or protein complex that selectively recognizes and physically associates with single-stranded DNA sequences that contain a high density of guanine nucleotides. This binding can occur in vitro or in vivo and does not necessarily imply catalytic activity; it is a binding function that may serve structural, protective, or regulatory roles.
Why Is G-rich single-stranded DNA binding Important in Cell Biology?
G-rich single-stranded DNA binding is important because it governs access to some of the most structurally dynamic and functionally critical regions of the genome, including telomeric overhangs and G-quadruplex-forming sequences. Proteins with this activity determine whether the G-rich strand is protected, folded, or made available for replication and repair, thereby influencing chromosome stability and cellular lifespan. Defects in these proteins are associated with cancer predisposition and premature aging syndromes, making this function a high-value target for both basic research and therapeutic development.
• Maintains telomere integrity by binding the G-rich 3' overhang and regulating telomerase access.
• Prevents inappropriate DNA damage responses at chromosome ends.
• Modulates G-quadruplex formation, which can affect transcription and replication.
• Supports CST-Polα/primase-mediated telomere C-strand synthesis.
• Contributes to genome-wide replication fork protection at G-rich sequences.
• Is implicated in cancer cell immortality and telomere maintenance mechanisms.
• Plays a role in plant telomere biology, highlighting evolutionary conservation.
• Can act as a nucleic acid chaperone, influencing RNA and DNA folding.
• Serves as a biomarker or therapeutic target in telomere-related diseases.
• Enables experimental dissection of single-stranded DNA metabolism using CRISPR models.
What Happens During G-rich single-stranded DNA binding?
Recognition of G-rich single-stranded DNA
In simple terms: A protein finds and attaches to a specific DNA sequence that is single-stranded and rich in guanine.
The first step in G-rich single-stranded DNA binding is the selective recognition of the single-stranded G-rich sequence by a DNA-binding domain, such as the oligonucleotide/oligosaccharide-binding (OB) fold found in POT1 and other telomere proteins. This recognition is sequence-specific and can occur at telomeric 3' overhangs or at internal G-rich tracts. Structural studies have revealed how these domains accommodate the G-rich strand while discriminating against double-stranded or non-G-rich DNA.
Protection and regulation of the G-rich overhang
In simple terms: Once bound, the protein shields the single-stranded DNA from being degraded or inappropriately processed.
Binding of proteins such as POT1 to the G-rich overhang protects it from nuclease digestion and prevents activation of DNA damage checkpoints. This protection is dynamic and cell-cycle regulated, as single-stranded G-rich DNA can be generated in the absence of telomerase. The bound state also regulates access of telomerase and other enzymes to the chromosome end.
Coordination with CST complex and DNA synthesis
In simple terms: The bound protein recruits other factors that synthesize the complementary DNA strand.
POT1 recruits and regulates the CST-Polα/primase complex at human telomeres, which is required for C-strand synthesis. This coordination ensures that the G-rich overhang is maintained at a proper length and that telomere replication is coupled to end protection. The CST complex itself can also bind G-rich single-stranded DNA, contributing to the regulation of telomere structure.
G-quadruplex formation and resolution
In simple terms: The G-rich strand can fold into a four-stranded knot, and binding proteins can help it fold or unfold.
G-rich single-stranded DNA has a propensity to fold into G-quadruplex structures, which can be stabilized or resolved by binding proteins. Circular dichroism studies have shown that single-stranded DNA-binding proteins can influence the conformation of G-quartet nucleic acids. Proteins such as CNBP bind G-rich single-stranded nucleic acids and may function as nucleic acid chaperones, facilitating structural transitions.
Cell cycle and telomerase-independent generation
In simple terms: The amount of G-rich single-stranded DNA changes during the cell cycle and can appear even without telomerase.
Single-stranded G-rich DNA is generated in a cell cycle-regulated manner, and this occurs even in the absence of telomerase. This suggests that G-rich single-stranded DNA binding proteins must operate in both telomerase-positive and telomerase-negative contexts to manage these transient structures. The regulation of this generation and binding is critical for maintaining genome stability.
Key Genes Involved in GO:1990955 G-rich single-stranded DNA binding
The following genes encode proteins that have been experimentally shown to bind G-rich single-stranded DNA or to be core components of complexes that perform this function.
| Gene | Major Role | Research Relevance |
|---|---|---|
| POT1 | Binds telomeric G-rich overhang; recruits CST-Polα/primase | Telomere protection, cancer, and aging research |
| CTC1 | Subunit of CST complex; binds G-rich ssDNA | Telomere C-strand synthesis and disease modeling |
| STN1 | Subunit of CST complex; involved in telomere maintenance | Telomere biology and genome stability |
| TEN1 | Subunit of CST complex; binds ssDNA | Telomere regulation and structural studies |
| CNBP | Binds G-rich single-stranded nucleic acids; nucleic acid chaperone | RNA/DNA metabolism and chaperone function |
| TDG | Thymine DNA glycosylase; RNA-binding with selectivity for G-rich sequences | Epigenetic regulation and G-rich sequence recognition |
| Rice telomere-binding proteins | Bind single-stranded G-rich telomere DNA | Plant telomere biology and comparative studies |
| Telomerase (TERT) | Elongates G-rich strand; interacts with G-rich ssDNA | Telomere elongation and cancer |
| RPA | Binds single-stranded DNA including G-rich tracts | DNA replication, repair, and recombination |
| CST complex | Binds G-rich ssDNA and regulates telomere replication | Telomere maintenance and disease |
| POT1-TPP1 complex | Protects G-rich overhang and regulates telomerase | Shelterin function and telomere length control |
| DNA polymerase alpha/primase | Synthesizes C-strand after POT1 recruitment | Telomere replication and CST coordination |
| G-quadruplex helicases (e.g., BLM, WRN) | Resolve G-quadruplex structures | Genome stability and G-rich DNA metabolism |
| CNBP homologs | Bind G-rich sequences in various organisms | Evolutionary conservation of G-rich ssDNA binding |
| Plant POT1-like proteins | Bind plant telomeric G-rich ssDNA | Plant telomere structure and function |
| TDG variants | Recognize G-rich RNA/DNA | Epigenetic and RNA biology |
How Is G-rich single-stranded DNA binding Regulated?
The binding of G-rich single-stranded DNA is regulated at multiple levels. Cell cycle-dependent generation of single-stranded G-rich DNA ensures that binding proteins act at specific phases. Post-translational modifications and protein-protein interactions, such as those within the shelterin and CST complexes, modulate the affinity and specificity of binding. Telomerase activity and telomere length feedback also influence the availability of G-rich overhangs for binding. Additionally, the folding state of the G-rich strand, including G-quadruplex formation, can be dynamically regulated by chaperone-like proteins such as CNBP.
G-rich single-stranded DNA binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| POT1 | Cancer predisposition, telomere dysfunction | Knockout and point mutation in cancer cell lines |
| CTC1 | Dyskeratosis congenita, telomere shortening | Knock-in of patient mutations in iPSCs |
| STN1 | Telomere biology disorders | Knockout in HEK293T cells |
| CNBP | RNA metabolism, potential neurodegeneration | Overexpression and knockout in neuronal cells |
| TDG | Epigenetic regulation, cancer | Point mutation of G-rich binding domain |
Cancer and Telomere Maintenance
Dysregulation of G-rich single-stranded DNA binding proteins such as POT1 can lead to telomere dysfunction and genomic instability, which are hallmarks of cancer. Mutations in POT1 have been associated with increased cancer risk, and targeting these proteins is a potential therapeutic strategy.
Premature Aging and Telomeropathies
Defects in CST complex subunits or POT1 can cause telomere shortening and premature aging syndromes, including dyskeratosis congenita. Impaired binding to G-rich single-stranded DNA disrupts telomere protection and C-strand synthesis, leading to disease phenotypes.
Neurodegeneration and RNA-Binding Proteins
Some proteins that bind G-rich single-stranded nucleic acids, such as TDG, are RNA-binding proteins with high selectivity for G-rich sequences, linking this function to RNA metabolism and potentially to neurological disorders. CNBP, a G-rich single-stranded nucleic acid-binding protein, may also play roles in cellular stress responses relevant to neurodegeneration.
From G-rich single-stranded DNA binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of POT1 affect telomere overhang length? | POT1 knockout cell line |
| How do point mutations in POT1 affect G-rich ssDNA binding? | Point mutation knock-in via CRISPR |
| Can CST complex rescue POT1 depletion? | Knock-in of tagged CST subunits |
| What is the role of CNBP in G-quadruplex regulation? | CNBP overexpression and knockout |
| Does TDG bind G-rich RNA in vivo? | Tagged knock-in of TDG for CLIP |
| How does cell cycle regulate G-rich ssDNA generation? | Synchronized cell populations with knockout of telomerase |
How to Study the G-rich single-stranded DNA binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| EMSA | Direct protein-DNA binding | Testing G-rich ssDNA binding specificity |
| CD spectroscopy | DNA conformation changes | G-quadruplex formation upon binding |
| ChIP | Genomic binding sites | Mapping G-rich ssDNA protein occupancy |
| CLIP | RNA binding sites | Identifying G-rich RNA targets of TDG |
| CRISPR knockout | Loss-of-function phenotypes | Telomere dysfunction studies |
| CRISPR knock-in | Mutant protein expression | Modeling patient mutations |
| Overexpression | Gain-of-function effects | Chaperone activity of CNBP |
Electrophoretic Mobility Shift Assay (EMSA)
EMSA is used to detect direct binding of proteins to G-rich single-stranded DNA probes. It can determine specificity and affinity and has been used to study proteins like CNBP and plant telomere-binding proteins.
Circular Dichroism (CD) Spectroscopy
CD spectroscopy can monitor conformational changes in G-rich single-stranded DNA upon protein binding, including G-quadruplex formation. This method provides structural insights into the binding event.
Chromatin Immunoprecipitation (ChIP) and CLIP
ChIP can identify genomic regions where G-rich single-stranded DNA binding proteins associate, while CLIP can map RNA binding sites for proteins like TDG. These techniques link binding to specific genomic loci.
CRISPR-Based Functional Genomics
CRISPR knockout, point mutation, and knock-in models allow researchers to test the functional consequences of altering G-rich single-stranded DNA binding proteins in cells. These models are essential for linking binding activity to telomere maintenance and disease phenotypes.
How CRISPR Can Be Used to Study GO:1990955 G-rich single-stranded DNA binding
Knockout
CRISPR knockout of genes encoding G-rich single-stranded DNA binding proteins, such as POT1 or CST subunits, allows researchers to assess loss-of-function phenotypes including telomere shortening, overhang loss, and DNA damage response activation.
Point Mutation
Introducing point mutations in the DNA-binding domain of proteins like POT1 can dissect the specific contribution of G-rich single-stranded DNA binding to telomere protection and recruitment of downstream factors.
Knock-in
Knock-in of tagged or patient-derived mutations in genes such as CTC1 or STN1 enables studies of protein localization, complex assembly, and disease mechanisms in an endogenous context.
Overexpression
Overexpression of G-rich single-stranded DNA binding proteins like CNBP can reveal gain-of-function effects on nucleic acid chaperone activity and G-quadruplex regulation.
How EDITGENE Supports G-rich single-stranded DNA binding Research
Researchers studying G-rich single-stranded DNA binding-related genes often need to determine whether a candidate gene is causally involved in telomere maintenance, genome stability, or disease. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models that answer these questions.
Contact EDITGENE today to design your custom CRISPR model for G-rich single-stranded DNA binding research.
Frequently Asked Questions About G-rich single-stranded DNA binding
What is G-rich single-stranded DNA binding?
G-rich single-stranded DNA binding (GO:1990955) is a molecular function defined as binding to G-rich, single-stranded DNA.
What genes are involved in G-rich single-stranded DNA binding?
Key genes include POT1, CTC1, STN1, TEN1, CNBP, and TDG, among others.
How is G-rich single-stranded DNA binding related to telomeres?
It is essential for protecting the telomeric 3' overhang and regulating telomerase and CST-Polα/primase access.
What diseases are associated with defects in G-rich single-stranded DNA binding?
Cancer, dyskeratosis congenita, and other telomere biology disorders have been linked to mutations in these proteins.
What methods are used to study G-rich single-stranded DNA binding?
Common methods include EMSA, CD spectroscopy, ChIP, CLIP, and CRISPR-based functional assays.
Can CRISPR be used to study G-rich single-stranded DNA binding?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect the function of these proteins.
What is the role of POT1 in G-rich single-stranded DNA binding?
POT1 binds the telomeric G-rich overhang and recruits CST-Polα/primase to regulate telomere replication.
How does CNBP function in G-rich single-stranded DNA binding?
CNBP binds G-rich single-stranded nucleic acids and may act as a nucleic acid chaperone.
Is G-rich single-stranded DNA binding conserved in plants?
Yes, rice proteins that bind single-stranded G-rich telomere DNA have been identified, indicating conservation.
What is the clinical relevance of G-rich single-stranded DNA binding?
It is relevant to cancer, aging, and genome instability, making it a target for therapeutic development.
Conclusion
G-rich single-stranded DNA binding (GO:1990955) is a critical molecular function that safeguards G-rich single-stranded DNA regions, particularly at telomeres, and regulates their processing. The proteins involved, such as POT1 and the CST complex, are essential for genome stability and are linked to cancer and premature aging. Continued research using CRISPR models and advanced biochemical assays will further illuminate the mechanistic details and therapeutic potential of this function.
References
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- 3. Gray DM et al.. 2002. CD of single-stranded, double-stranded, and G-quartet nucleic acids in complexes with a single-stranded DNA-binding protein.. Enantiomer 7(2-3):49-58 PMID: 12108634
- 4. Mansoubi S et al.. 2024. Comparison of Telomere Structure in Eukaryotes.. Arch Razi Inst 79(6):1365-1374 PMID: 40606259
- 5. Dionne I et al.. 1996. Cell cycle-regulated generation of single-stranded G-rich DNA in the absence of telomerase.. Proc Natl Acad Sci U S A 93(24):13902-7 PMID: 8943033
- 6. McGregor LA et al.. 2023. Thymine DNA glycosylase is an RNA-binding protein with high selectivity for G-rich sequences.. J Biol Chem 299(4):104590 PMID: 36889585
- 7. Kim JH et al.. 1998. Rice proteins that bind single-stranded G-rich telomere DNA.. Plant Mol Biol 36(5):661-72 PMID: 9526498
- 8. Armas P et al.. 2008. Cellular nucleic acid binding protein binds G-rich single-stranded nucleic acids and may function as a nucleic acid chaperone.. J Cell Biochem 103(3):1013-36 PMID: 17661353
