title: Yeast pol4 promotes tel1-regulated chromosomal translocations.
abstract: DNA double-strand breaks (DSBs) are one of the most dangerous DNA lesions, since their erroneous repair by nonhomologous end-joining (NHEJ) can generate harmful chromosomal rearrangements. PolX DNA polymerases are well suited to extend DSB ends that cannot be directly ligated due to their particular ability to bind to and insert nucleotides at the imperfect template-primer structures formed during NHEJ. Herein, we have devised genetic assays in yeast to induce simultaneous DSBs in different chromosomes in vivo. The repair of these breaks in trans could result in reciprocal chromosomal translocations that were dependent on classical Ku-dependent NHEJ. End-joining events leading to translocations were mainly based on the formation of short base pairing between 3'-overhanging DNA ends coupled to gap-filling DNA synthesis. A major proportion of these events were specifically dependent on yeast DNA polymerase Pol4 activity. In addition, we have discovered that Pol4-Thr(540) amino acid residue can be phosphorylated by Tel1/ATM kinase, which could modulate Pol4 activity during NHEJ. Our data suggest that the role of Tel1 in preventing break-induced chromosomal translocations can, to some extent, be due to its stimulating effect on gap-filling activity of Pol4 to repair DSBs in cis. Overall, this work provides further insight to the molecular mechanisms of DSB repair by NHEJ and presents a new perspective to the understanding of how chromosomal translocations are formed in eukaryotic cells.
authors.affiliation: Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid/CSIC, Madrid, Spain. jose.ruiz@cabimer.es
authors.forename: Jose F
authors.initials: JF
authors.lastname: Ruiz
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pardo
authors.forename: Guillermo
authors.initials: G
authors.lastname: Sastre-Moreno
authors.forename: Andrés
authors.initials: A
authors.lastname: Aguilera
authors.forename: Luis
authors.initials: L
authors.lastname: Blanco
mesh_terms: D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D019951:DNA Polymerase beta / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D014178:Translocation, Genetic / Q000235:genetics*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae; D019951:DNA Polymerase beta; C084892:POL4 protein, S cerevisiae