GO:1990238 double-stranded DNA endonuclease activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1990238 describes the catalytic activity of enzymes that hydrolyze ester linkages within double-stranded DNA to create internal breaks.
• This activity is central to CRISPR-Cas12a and Cas9 genome editing, where the endonuclease introduces site-specific double-strand breaks [1,2].
• Structural studies reveal that Cas12a uses a single RuvC domain to cleave both strands of dsDNA, while Cas9 employs two nuclease domains [2,3].
• Beyond CRISPR, enzymes such as Artemis, Apollo, MLH1-MLH3, and Fanzor exhibit double-stranded DNA endonuclease activity in DNA repair, meiosis, and telomere maintenance [4,5,7,8].
• Dysregulation of these enzymes is linked to cancer, immunodeficiency, and genome instability, making them key therapeutic targets [4,7].
• CRISPR-based knockout, knock-in, and point-mutation models are essential to dissect the precise roles of these endonucleases in cells.
Description
Double-stranded DNA endonuclease activity (GO:1990238) is a molecular function defined as the catalysis of hydrolysis of ester linkages within a double-stranded DNA molecule, creating internal breaks. This activity is fundamental to many biological processes, including genome editing, DNA repair, meiotic recombination, and telomere maintenance [2,4,5]. Researchers study this activity to understand how cells maintain genomic integrity and to harness programmable nucleases for therapeutic applications [1,6]. The CRISPR-associated proteins Cas12a and Cas9 are prominent examples of enzymes with this activity, and their mechanisms have been extensively characterized [1,2,3]. In addition to CRISPR systems, eukaryotic enzymes such as Artemis, Apollo, and MLH1-MLH3 also possess double-stranded DNA endonuclease activity and play critical roles in non-homologous end joining, telomere processing, and mismatch repair [4,5,7]. Understanding the molecular details of these enzymes is essential for developing targeted interventions in diseases characterized by genomic instability [4,7].
double-stranded DNA endonuclease activity At A Glance
| GO ID | GO:1990238 |
|---|---|
| GO term | double-stranded DNA endonuclease activity |
| Ontology | molecular_function |
| Synonym | double-stranded DNA endodeoxyribonuclease activity; dsDNA-specific endodeoxyribonuclease activity |
| Definition | Catalysis of the hydrolysis of ester linkages within a double-stranded DNA molecule by creating internal breaks. |
| Major function | Introduction of site-specific double-strand breaks in DNA for genome editing, repair, and recombination. |
| Representative enzymes | Cas12a, Cas9, Artemis, Apollo, MLH1-MLH3, Fanzor. |
| Cofactors | Metal ions (e.g., Mg2+) are typically required for catalysis. |
| Subcellular location | Nucleus (for eukaryotic enzymes); also used in vitro for CRISPR applications. |
What Is GO:1990238?
GO:1990238, double-stranded DNA endonuclease activity, refers to the catalytic function of an enzyme that cleaves phosphodiester bonds within a double-stranded DNA molecule, producing internal breaks rather than terminal nicks. This activity requires a double-stranded DNA substrate and generates DNA ends that can be further processed by cellular machinery [1,2].
Why Is double-stranded DNA endonuclease activity Important in Cell Biology?
Double-stranded DNA endonuclease activity is essential for genome editing technologies such as CRISPR-Cas12a and Cas9, which rely on this activity to introduce targeted double-strand breaks [1,2]. It also plays critical roles in fundamental cellular processes, including DNA repair, meiotic recombination, and telomere maintenance [4,5,7]. Dysregulation of these enzymes can lead to genomic instability, cancer, and immunodeficiency, making them important targets for therapeutic development [4,7]. Furthermore, understanding the mechanisms of these enzymes informs the design of more precise genome-editing tools and inhibitors [3,8].
• Enables programmable genome editing by CRISPR-Cas12a and Cas9 [1,2].
• Required for non-homologous end joining and V(D)J recombination via Artemis.
• Essential for meiotic crossover formation through MLH1-MLH3.
• Protects telomeres from inappropriate end-joining by Apollo.
• Involved in bacterial immunity against phages via CRISPR systems [1,3].
• Contributes to DNA damage response and repair pathways.
• Mutations in these enzymes are associated with cancer predisposition.
• Target for antiviral and anticancer drug discovery.
• Facilitates structural studies of protein-DNA complexes [3,8].
• Provides tools for synthetic biology and gene therapy.
What Happens During double-stranded DNA endonuclease activity?
Substrate recognition and binding
In simple terms: The enzyme first finds and binds to a specific DNA sequence or structure.
Double-stranded DNA endonucleases recognize their target sites through protein-DNA interactions. For example, Cas12a uses a guide RNA to locate a complementary dsDNA sequence, forming an R-loop and inducing conformational changes that activate the nuclease [1,3]. Cas9 similarly interrogates DNA for a protospacer adjacent motif (PAM) and guide RNA complementarity. Other enzymes, such as Artemis, are recruited to DNA ends by protein partners like DNA-PK.
Catalytic activation and strand cleavage
In simple terms: Once bound, the enzyme cuts both strands of the DNA.
Activation triggers the nuclease domain to hydrolyze phosphodiester bonds. Cas12a utilizes a single RuvC domain to cleave the non-target strand and then the target strand, generating a staggered double-strand break [1,3]. Cas9 employs two separate nuclease domains, HNH and RuvC, each cleaving one strand. Fanzor, a eukaryotic homolog, also uses a RuvC domain for dsDNA cleavage. MLH1-MLH3 introduces double-strand breaks during meiosis, and its activity is regulated by ATP and mismatch repair proteins.
Post-cleavage processing and repair
In simple terms: After cutting, the DNA ends are processed by cellular repair machinery.
The double-strand breaks created by these enzymes are substrates for cellular repair pathways. Cas9 remains tightly bound to the cleaved DNA, and accessory factors like HLTF can displace it to allow break processing. Artemis, after activation by DNA-PK autophosphorylation, opens DNA hairpins during non-homologous end joining. Apollo protects telomeres by processing leading-end overhangs, and its access is controlled by DNA-PK.
Key Genes Involved in GO:1990238 double-stranded DNA endonuclease activity
The following genes encode proteins with demonstrated double-stranded DNA endonuclease activity or are critical regulators of this activity.
| Gene | Major Role | Research Relevance |
|---|---|---|
| Cas12a (Cpf1) | RNA-guided dsDNA endonuclease | Genome editing; creates staggered cuts [1,3] |
| Cas9 | RNA-guided dsDNA endonuclease | Genome editing; creates blunt cuts |
| MLH1 | Component of MLH1-MLH3 endonuclease | Meiotic recombination; mismatch repair |
| MLH3 | Component of MLH1-MLH3 endonuclease | Meiotic recombination; crossover formation |
| Apollo (DCLRE1B) | Telomere endonuclease | Telomere protection; DNA-PK regulated |
| Artemis (DCLRE1C) | dsDNA endonuclease in NHEJ | V(D)J recombination; immunodeficiency |
| Fanzor | Eukaryotic RNA-guided endonuclease | Genome editing; structural diversity |
| HLTF | Helicase, displaces Cas9 | Facilitates DNA break processing |
| DNA-PKcs | Kinase, regulates Artemis and Apollo | DNA damage response; NHEJ [5,7] |
| RuvC domain | Catalytic nuclease domain | Common to Cas12a, Cas9, Fanzor [1,2,8] |
| HNH domain | Nuclease domain in Cas9 | Cleaves target strand |
| Guide RNA | Targeting component | Programs Cas12a/Cas9 specificity [1,2] |
| Mg2+ | Cofactor for catalysis | Essential for nuclease activity |
| ATP | Regulates MLH1-MLH3 | Modulates endonuclease activity |
| PCNA | Processivity factor | May interact with MLH1-MLH3 |
| EXO1 | Exonuclease in mismatch repair | Cooperates with MLH1-MLH3 |
| RPA | Single-strand DNA binding | Involved in repair after cleavage |
How Is double-stranded DNA endonuclease activity Regulated?
Double-stranded DNA endonuclease activity is tightly regulated to prevent genomic instability. DNA-PK controls the access of Apollo to leading-end telomeres through phosphorylation. Artemis activity requires DNA-PK-mediated autophosphorylation for activation. MLH1-MLH3 endonuclease is regulated by ATP binding and hydrolysis, and its activity is influenced by mismatch repair proteins. Cas12a and Cas9 are regulated by guide RNA binding and conformational changes upon target recognition [1,2]. Additionally, HLTF disrupts Cas9-DNA post-cleavage complexes to allow DNA break processing.
double-stranded DNA endonuclease activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MLH1 | Hereditary nonpolyposis colorectal cancer | Knockout in HCT116 cells; point mutation in meiotic cells |
| MLH3 | Meiotic defects; cancer predisposition | Knockout mouse models; knock-in of patient mutations |
| Artemis (DCLRE1C) | RS-SCID | Knockout in HEK293T; knock-in of patient mutations |
| Apollo (DCLRE1B) | Telomere dysfunction; cancer | Knockout in HeLa; overexpression of mutant |
| Cas12a | Genome editing tool | Overexpression in mammalian cells; library screening [1,3] |
Cancer and genomic instability
Dysregulation of double-stranded DNA endonucleases can lead to genomic instability and cancer. For example, mutations in MLH1 or MLH3 impair meiotic recombination and mismatch repair, contributing to hereditary nonpolyposis colorectal cancer and other malignancies. Artemis deficiency causes radiosensitive severe combined immunodeficiency (RS-SCID) due to defective V(D)J recombination. Targeting these enzymes with small molecule inhibitors is a potential anticancer strategy.
Immunodeficiency
Artemis is essential for V(D)J recombination, and its loss-of-function mutations result in RS-SCID, characterized by lack of B and T lymphocytes. This highlights the critical role of double-stranded DNA endonuclease activity in immune system development.
Telomere dysfunction
Apollo (DCLRE1B) protects telomeres by processing leading-end overhangs. Its dysregulation can lead to telomere fusions and genomic instability, which are hallmarks of cancer and premature aging.
From double-stranded DNA endonuclease activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X have double-stranded DNA endonuclease activity? | In vitro cleavage assay with purified protein and dsDNA substrate |
| What is the role of gene X in DNA repair? | Knockout cell line (e.g., HEK293T) followed by DNA damage sensitivity assays |
| How does a point mutation affect endonuclease activity? | Point mutation knock-in using CRISPR-Cas9 |
| Where does the enzyme localize in cells? | Tagged knock-in with fluorescent protein |
| Can overexpression of gene X induce genomic instability? | Overexpression cell model and comet assay |
| What are the off-target effects of Cas12a? | Library screening and GUIDE-seq [1,3] |
How to Study the double-stranded DNA endonuclease activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro cleavage assay | Direct endonuclease activity | Characterize Cas12a, Cas9, Artemis [1,7] |
| Cryo-EM | 3D structure of protein-DNA complexes | Understand catalytic mechanism [3,8] |
| CRISPR knockout | Loss-of-function phenotype | Study gene function in cells |
| Knock-in point mutation | Effect of specific mutations | Model patient variants |
| Overexpression | Gain-of-function effects | Induce genomic instability |
| Comet assay | DNA breaks in cells | Assess DNA damage |
| γH2AX staining | DNA damage foci | Quantify double-strand breaks |
| Library screening | Identify modifiers of endonuclease activity | Discover new factors |
In vitro cleavage assays
Purified enzymes are incubated with double-stranded DNA substrates, and cleavage products are analyzed by gel electrophoresis. This method directly measures double-stranded DNA endonuclease activity and is used to characterize Cas12a, Cas9, and Fanzor [1,2,8].
Structural biology (cryo-EM and X-ray crystallography)
Structures of Cas12a, Cas9, and Fanzor in complex with guide RNA and DNA reveal the molecular basis of substrate recognition and catalysis [2,3,8].
CRISPR-based genome editing and screening
Knockout, knock-in, and point mutation models are generated to study the cellular roles of endonucleases. Library screening identifies genes that modulate editing efficiency or DNA repair.
DNA damage and repair assays
Comet assay, γH2AX staining, and survival assays measure the impact of endonuclease activity on genomic integrity [5,7].
How CRISPR Can Be Used to Study GO:1990238 double-stranded DNA endonuclease activity
Knockout
CRISPR-Cas9 knockout of genes encoding double-stranded DNA endonucleases (e.g., MLH1, Artemis) allows researchers to study loss-of-function phenotypes, such as defective DNA repair or meiotic recombination [4,7].
Point Mutation
Introducing specific point mutations (e.g., in the catalytic domain of Cas12a or MLH3) via CRISPR knock-in helps dissect the contribution of individual residues to endonuclease activity and substrate specificity [3,4].
Knock-in
Knock-in of tagged versions (e.g., GFP, FLAG) of endonucleases enables live-cell imaging and proteomic studies to determine localization and interaction partners.
Overexpression
Overexpression of wild-type or mutant endonucleases in cell lines can induce DNA damage and reveal oncogenic potential or synthetic lethality.
How EDITGENE Supports double-stranded DNA endonuclease activity Research
Researchers studying double-stranded DNA endonuclease activity-related genes often need to determine whether a candidate gene is causally involved in DNA cleavage, repair, or genome stability. EDITGENE provides comprehensive CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for double-stranded DNA endonuclease activity research.
Frequently Asked Questions About double-stranded DNA endonuclease activity
What is double-stranded DNA endonuclease activity?
It is the catalytic activity of an enzyme that cleaves phosphodiester bonds within double-stranded DNA, creating internal breaks, as defined by GO:1990238.
What genes are involved in double-stranded DNA endonuclease activity?
Key genes include Cas12a, Cas9, MLH1, MLH3, Apollo (DCLRE1B), Artemis (DCLRE1C), and Fanzor [1,2,4,5,7,8].
How does Cas12a cut double-stranded DNA?
Cas12a uses a single RuvC domain to sequentially cleave the non-target and target strands, generating a staggered double-strand break [1,3].
What is the role of Artemis in DNA repair?
Artemis is activated by DNA-PK autophosphorylation and opens DNA hairpins during non-homologous end joining and V(D)J recombination.
How is Apollo regulated at telomeres?
DNA-PK controls Apollo's access to leading-end telomeres, preventing inappropriate end-joining.
What diseases are associated with defective double-stranded DNA endonuclease activity?
Mutations in Artemis cause RS-SCID, while MLH1/MLH3 defects are linked to cancer and meiotic failure [4,7].
Can CRISPR be used to study double-stranded DNA endonuclease activity?
Yes, CRISPR knockout, knock-in, and point mutation models are widely used to dissect the function of these enzymes.
What methods measure double-stranded DNA endonuclease activity?
In vitro cleavage assays, cryo-EM, comet assay, and γH2AX staining are commonly used [1,3,5,6].
What is Fanzor?
Fanzor is a eukaryotic RNA-guided endonuclease with a RuvC domain that cleaves double-stranded DNA, offering a new genome-editing tool.
How does HLTF affect Cas9?
HLTF disrupts Cas9-DNA post-cleavage complexes, allowing DNA break processing and repair.
Conclusion
Double-stranded DNA endonuclease activity (GO:1990238) is a fundamental molecular function with broad implications in genome editing, DNA repair, and disease. The diversity of enzymes exhibiting this activity, from CRISPR effectors to eukaryotic repair factors, underscores its evolutionary importance. Continued research using CRISPR-based models and structural biology will further illuminate the mechanisms and therapeutic potential of these enzymes.
References
- 1. Chen JS et al.. 2018. CRISPR-Cas12a target binding unleashes indiscriminate single-stranded DNase activity.. Science 360(6387):436-439 PMID: 29449511
- 2. Sternberg SH et al.. 2014. DNA interrogation by the CRISPR RNA-guided endonuclease Cas9.. Nature 507(7490):62-7 PMID: 24476820
- 3. Swarts DC et al.. 2017. Structural Basis for Guide RNA Processing and Seed-Dependent DNA Targeting by CRISPR-Cas12a.. Mol Cell 66(2):221-233.e4 PMID: 28431230
- 4. Cannavo E et al.. 2020. Regulation of the MLH1-MLH3 endonuclease in meiosis.. Nature 586(7830):618-622 PMID: 32814904
- 5. Sonmez C et al.. 2024. DNA-PK controls Apollo's access to leading-end telomeres.. Nucleic Acids Res 52(8):4313-4327 PMID: 38407308
- 6. Reginato G et al.. 2024. HLTF disrupts Cas9-DNA post-cleavage complexes to allow DNA break processing.. Nat Commun 15(1):5789 PMID: 38987539
- 7. Goodarzi AA et al.. 2006. DNA-PK autophosphorylation facilitates Artemis endonuclease activity.. EMBO J 25(16):3880-9 PMID: 16874298
- 8. Xu P et al.. 2024. Structural insights into the diversity and DNA cleavage mechanism of Fanzor.. Cell 187(19):5238-5252.e20 PMID: 39208796
