DNA ligase

DNA ligase is an enzyme that facilitates the joining of DNA strands together by forming a phosphodiester bond. It plays a crucial role in the process of DNA replication and DNA repair.

Function

DNA ligase is responsible for repairing the millions of DNA breaks generated during the normal course of a cell's life. In the absence of DNA ligase, cells can become unstable and die. DNA ligase is also essential for the process of DNA replication. During replication, the DNA molecule is broken into two strands. DNA ligase is responsible for rejoining these two strands to form a complete DNA molecule.

Types

There are three types of DNA ligase: DNA ligase I, DNA ligase III, and DNA ligase IV. Each type has a different role in the cell.

• DNA ligase I is involved in DNA replication and repair.
• DNA ligase III is involved in DNA repair.
• DNA ligase IV is involved in DNA repair and is essential for V(D)J recombination, a process that generates diversity in B-cell and T-cell receptors in the immune system.

Clinical significance

Mutations in the genes encoding DNA ligase can lead to immunodeficiency syndromes, such as LIG4 syndrome, which is characterized by immunodeficiency, abnormal sensitivity to DNA-damaging agents, and a variety of other symptoms.

See also

• DNA replication
• DNA repair
• Enzyme
• Phosphodiester bond

References

• 
  DNA Repair Process
• 
  DNA Ligase Enzyme
• 
  Diagram of Ligase
• 
  DNA Ligation Process