DNAligaasinella

DNAligaasinella is a hypothetical DNA ligase used in educational and fictional biology contexts to illustrate the chemical logic of DNA nick sealing. The name combines the general term DNA ligase with a diminutive genus-like suffix, signaling its status as a model protein rather than a defined natural product. It is not described as existing in nature outside of teaching examples.

Function and mechanism: In the model, DNAligaasinella catalyzes the formation of a phosphodiester bond at DNA nicks during replication, repair, or cloning workflows. The enzyme is depicted as operating via a conserved two-step mechanism common to many ligases: first, an active-site lysine forms a covalent ligase-AMP intermediate by reacting with ATP; second, the 5' phosphate at the nick is adenylated and the 3' hydroxyl attacks to seal the strand, releasing AMP. The result is a continuous sugar-phosphate backbone.

Structure and properties: In typical educational depictions, DNAligaasinella is shown as a modular protein with a catalytic core surrounded by DNA-binding regions that recognize a nicked duplex. It is described as requiring divalent metal ions and ATP, and functioning under conditions analogous to other ligases used in classroom settings.

Context and uses: The enzyme serves as a teaching tool to explain ligation steps in plasmid construction, genome repair, and DNA sequencing workflows. It has no experimental record and should be distinguished from real DNA ligases such as T4 DNA ligase and mammalian ligases.

See also: DNA ligase, DNA nick, ligation, plasmid cloning.