Terminal Deoxynucleotidyl Transferase in the Synthesis and Modification of Nucleic Acids

The terminal deoxynucleotidyl transferase (TdT) belongs to the X family of DNA polymerases. This unusual polymerase catalyzes the template‐independent addition of random nucleotides on 3′‐overhangs during V(D)J recombination. The biological function and intrinsic biochemical properties of the TdT have spurred the development of numerous oligonucleotide‐based tools and methods, especially if combined with modified nucleoside triphosphates. Herein, we summarize the different applications stemming from the incorporation of modified nucleotides by the TdT. The structural, mechanistic, and biochemical properties of this polymerase are also discussed. Turning the (nucleo)tide: The terminal deoxynucleotidyl transferase (TdT) catalyzes the template‐independent addition of nucleotides at the 3′‐ends of single‐stranded DNA substrates. The combination of the TdT with modified nucleoside triphosphates is an alluring method for the development of nucleic acid‐based tools and assays, which are the topic of this minireview.