De Novo DNA Synthesis by Human DNA Polymerase λ, DNA Polymerase μ and Terminal Deoxyribonucleotidyl Transferase

✍ Scribed by Kristijan Ramadan; Igor V Shevelev; Giovanni Maga; Ulrich Hübscher

• Book ID: 116661282
• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 825 KB
• Volume: 339
• Category: Article
• ISSN: 0022-2836
• DOI: 10.1016/j.jmb.2004.03.056

✦ Synopsis

DNA polymerases (pols) catalyse the synthesis of DNA. This reaction requires a primer-template DNA in order to grow from the 3 0 OH end of the primer along the template. On the other hand terminal deoxyribonucleotidyl transferase (TdT) catalyses the addition of nucleotides at the 3 0 OH end of a DNA strand, without the need of a template. Pol l and pol m are ubiquitous enzymes, possess both DNA polymerase and terminal deoxyribonucleotidyl transferase activities and belong to pol X family, together with pol b and TdT. Here we show that pol l, pol m and TdT, all possess the ability to synthesise in vitro short fragments of DNA in the absence of a primer-template or even a primer or a template in the reaction. The DNA synthesised de novo by pol l, pol m and TdT appears to have an unusual structure. Furthermore we found that the amino acid Phe506 of pol l is essential for the de novo synthesis. This novel catalytic activity might be related to the proposed functions of these three pol X family members in DNA repair and DNA recombination.