DNA--- the information-holding material of the cell which had scientists stumped for decades. Is it possible that something that seems so simple can hold the extensive information needed for a cell to function? How can a pattern of A, C, T, and G encode the various specialized proteins necessary for advanced life to occur? How is this “knowledge” passed on from the mother cell to the daughter cells?
The mechanism of the method of genetic inheritance, was one that obligated the careers of many scientists. The process of DNA replication is thought to be quite well known today as a result of their work.
Needless to say, the process of DNA synthesis is absolutely essential during cell proliferation as seen in reproduction and growth. DNA Ligase is a protein which functions during the replication process of DNA to ensure that the complementary, double-stranded structure of DNA results. DNA Ligase functions in piecing together the Okazaki fragments of the lagging strand to form a continuous complementary strand. The reaction it catalyzes requires the use of ATP. AMP is added to the active site releasing pyrophosphate. DNA then enters the active site and the AMP is used to attach together the 3’ and 5’ ends of the lagging strand.
|DNA Ligase interacting with ATP|
Not only is DNA Ligase in action during DNA synthesis, but also during DNA repair. Some harsh environmental or intracellular factors, such as UV radiation or radicals, can cause breaks in the DNA chain requiring DNA Ligase activity. The structure of DNA Ligase facilitates its ability to recognize the damage and catalyze the crucial reactions to repair our information source. The enzyme is composed of two domains with a deep gap between them where both DNA and ATP are bound. Upon the binding of DNA and ATP, pyrophosphate is released, and the strand is returned to its former, continuous state.
If not for DNA Ligase, genetic information would not be able to be passed from mother to daughter cell, and each event resulting in the breakage of a DNA strand would result in malfunction and potentially cell death.