title: De novo DNA synthesis by human DNA polymerase lambda, DNA polymerase mu and terminal deoxyribonucleotidyl transferase.
abstract: DNA polymerases (pols) catalyse the synthesis of DNA. This reaction requires a primer-template DNA in order to grow from the 3'OH end of the primer along the template. On the other hand terminal deoxyribonucleotidyl transferase (TdT) catalyses the addition of nucleotides at the 3'OH end of a DNA strand, without the need of a template. Pol lambda and pol micro are ubiquitous enzymes, possess both DNA polymerase and terminal deoxyribonucleotidyl transferase activities and belong to pol X family, together with pol beta and TdT. Here we show that pol lambda, pol micro 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 lambda, pol micro and TdT appears to have an unusual structure. Furthermore we found that the amino acid Phe506 of pol lambda 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.
authors.affiliation: Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
authors.forename: Kristijan
authors.initials: K
authors.lastname: Ramadan
authors.forename: Igor V
authors.initials: IV
authors.lastname: Shevelev
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maga
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hübscher
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D006801:Humans
chemical_list: D017931:DNA Primers; C415367:DNA polymerase beta2; C407743:DNA polymerase mu; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase