DNAligatie

DNAligatie refers to the enzymatic process by which DNA strands are joined end-to-end by DNA ligases. It is a fundamental step in DNA replication, repair, and many genetic engineering applications, enabling continuous DNA backbones after the removal of nucleotides, nicking, or fragment joining.

The core reaction is the formation of a phosphodiester bond at a nick between a 3' hydroxyl and a 5' phosphate. DNA ligases require energy, supplied by cofactors such as ATP or NAD+, depending on the ligase type. In eukaryotes and archaea, ATP-dependent ligases are common, while many bacterial ligases use NAD+. In laboratory settings, engineered enzymes like T4 DNA ligase (ATP-dependent) are widely used for cloning. Ligation can join cohesive (sticky) ends or blunt ends, with efficiency influenced by end compatibility, DNA concentration, and reaction conditions.

Biological roles of DNAligatie include sealing gaps during lagging-strand synthesis (joining Okazaki fragments), repairing single-strand nicks, and participating in double-strand break repair pathways such as non-homologous end joining, where ligase IV plays a key role in complex formation with XRCC4. Mitochondrial DNA maintenance also relies on ligation activity.

In research and biotechnology, DNAligatie is central to cloning, plasmid construction, and assembly of DNA fragments. Considerations for successful ligation include end compatibility, phosphorylation status, and the choice of ligase and cofactors. While highly versatile, blunt-end ligation is typically less efficient than cohesive-end ligation, often requiring optimization or alternative strategies.