DNA ligase also known as molecular glue, is an essential enzyme that assumes a focal part in the duplication and replication of DNA. The molecular glue function guarantees DNA stability which allows cells to precisely perform DNA repair and DNA replication processes. The Journal of Molecular Biology published an article suggesting that DNA ligases sustain genome integrity through DNA break repairs which occur during replication, differentiation, immune functions, and DNA damage cases. Recent scientific research uses DNA ligases as potential tools to create treatments for immunodeficiency syndrome, mutational disorders, and cancer therapies. In this article, we will dig into the structure, role, types, mechanisms, and uses of DNA ligase, featuring its basic job in biotechnology and medication.
Structure of DNA ligase
DNA ligase is a highly conserved enzyme tracked down in all forms of life, from microscopic organisms to humans. Despite varieties in structure among various species, the major parts and usefulness of DNA ligase remain remarkably similar. The enzyme comprises the following domains.
Adenylation domain
This site attaches to ATP or NAD⁺, which fills in as an energy source for the ligation response.
DNA-Binding domain
This area is associated especially with the DNA substrate, guaranteeing the enzyme’s activity is designated to the right site.
Catalytic domain
The reactant area works with the development of a phosphodiester bond between DNA parts.
Function of DNA ligase in genetic engineering
The enzymatic catalyst activity of DNA ligase connects DNA strands through phosphodiester bond formation between the hydroxyl group at position 3′ and the 5′-phosphate group of nearby DNA strands. This cycle is essential for:
- DNA replication: DNA ligase seals Okazaki fragments, and short DNA sequences are incorporated on the lagging strand during replication.
- DNA repair: The protein assumes a key part in fixing single- and double-strand breaks brought about by environmental elements, like radiation, or by cell processes.
- Recombination: DNA ligase works with the incorporation of foreign DNA into host genomes during genomic recombination processes.
Types of DNA ligase
DNA ligases are classified because of their energy source for the ligation process.
- ATP-Dependent ligases: These catalysts use ATP to perform the ligation response. They are regularly tracked down in eukaryotes.
- NAD⁺-Dependent ligases: Found mostly in prokaryotes, these biological catalyst uses NAD⁺ as the energy source.
- T4 DNA ligase: This is a generally utilized ATP-dependent ligase obtained from the T4 bacteriophage, especially preferred in molecular biology applications.
Mechanism of action
DNA ligase performs its mechanism through three sequential processes.
Adenylation
The enzyme binds to ATP or NAD⁺ to create an enzyme AMP intermediate which yields pyrophosphate (PPi) or nicotinamide mononucleotide (NMN).
DNA binding and activation
The enzyme-AMP intermediate attaches to the broken DNA fragment. The AMP is moved to the 5′- phosphate group of the DNA, initiating it for the ligation response.
Phosphodiester bond formation
The 3′- hydroxyl group of DNA forms a chemical bond with the 5′- phosphate group through phosphodiester bond formation while releasing AMP as an end product. The DNA strand is now completely fixed.
| Type of DNA Ligase | Energy Source | Organisms Found In | Key Applications |
| ATP-Dependent | ATP | Eukaryotes | Genome repair, cloning |
| NAD⁺-Dependent | NAD⁺ | Prokaryotes | Bacterial DNA replication |
| T4 DNA Ligase | ATP | Bacteriophage | Molecular cloning |
Applications of DNA ligase
DNA ligase has revolutionized molecular biology, biochemistry, biotechnology, and medication. Its capacity to join DNA broken pieces has made it a basic device for different applications.
- Molecular cloning: The process of embedding DNA fragments into vectors requires DNA ligase which enables the development of desired qualities in a host organism.
- Polymerase chain reaction (PCR): DNA ligase serves as the main amplification tool for specific DNA sequences within particular PCR variations including ligase chain response (LCR). It also helps in DNA fingerprinting.
- Genome editing: During the genome modification process CRISPR-Cas9 methods rely on DNA ligase to repair the double-strand breaks that occur during gene therapy and genome editing procedures.
- DNA sequencing: The sequencing-by-ligation method requires DNA ligase to ensure correct DNA sequence determination.
- Diagnostics: DNA or RNA sequence recognition for microorganisms and inherited problems occurs through ligase-based testing.
DNA ligase in DNA repair mechanisms
DNA repair is a basic cycle that guarantees genomic stability. DNA ligase adds to several repair pathways.
- Base excision repair (BER): DNA ligase acts to mend the single-strand breaks that develop throughout base damage repair.
- Nucleotide excision repair (NER): DNA ligase enzymes help restore damages caused by sun exposure along with chemical damage.
- Non-Homologous end joining (NHEJ): DNA ligase executes a recurring mechanism to link DNA breakage sites without requiring sequence homology patterns.
- Homologous recombination (HR): The error-free repair process allows DNA ligase to mend DNA strands through the usage of homologous sequences.
DNA ligase deficiencies and disorders
Mutations or lack of DNA ligase can prompt extreme hereditary disorders and an inclination to malignant growth. For example:
- Ligase IV syndrome: Brought about by mutations in the LIG4 gene, this condition is portrayed by immunodeficiency, developmental delay, and expanded malignant growth risk leading to cancer.
- Xeroderma pigmentosum (XP): Deformities in DNA repair pathways including DNA ligase add to outrageous sensitivity to UV radiation resulting in skin cancer.
Advancements in DNA ligase research
Recent research has extended how we might interpret DNA ligase and its possible applications.
- Engineering enhanced ligases: Researchers are designing engineered ligases with further developed effectiveness and specificity for biotechnological applications.
- Synthetic biology: DNA ligase is being utilized to gather synthetic genomes, making way for new organisms and bioengineered frameworks.
- Therapeutic targets: DNA ligase inhibitors are being investigated as possible treatments for malignant growth and cancer, as they can sensitize cancer cells to DNA-harming agents.
The research published in 2024 in Frontiers in Oncology Journal reported the combined therapeutic value of selective inhibition of DNA ligase IV gene and doxorubicin (DNA-damaging agents) increased cellular apoptosis of cancerous cells for thyroid cancer treatment.
Challenges and future perspectives
While DNA ligase has transformed molecular biology, certain difficulties are still considered as challenges.
- Substrate specificity: Upgrading the capacity of DNA ligase to perceive and tie assorted DNA substrates remains an area of dynamic exploration.
- Thermal stability: Creating ligases with higher thermal stability can work on their application in PCR and other high-temperature processes.
- Cost reduction: Making high-quality DNA ligase more reasonable will grow its openness to scientists around the world.
Molecular glue of life
DNA ligase acts as a core enzyme to sustain DNA replication together with DNA repair and recombination sequences. The flexible and high-quality properties of DNA ligase establish its vital position in biochemistry, molecular biology research, and biotechnology applications. The forward momentum of scientific advancement will be driven by DNA ligase because research continues unveiling its complex nature to create innovative applications for medication and genetic engineering fields along with genetics and genomics.
“DNA ligase, the ‘molecular glue of life,’ keeps on transforming medication and biotechnology. As scientists refine its applications, from CRISPR-based genome editing to accurate malignant growth treatments, its role in designing the future of hereditary disorders remains unmatched.”
