title: 14-3-3 Proteins regulate exonuclease 1-dependent processing of stalled replication forks.
abstract: Replication fork integrity, which is essential for the maintenance of genome stability, is monitored by checkpoint-mediated phosphorylation events. 14-3-3 proteins are able to bind phosphorylated proteins and were shown to play an undefined role under DNA replication stress. Exonuclease 1 (Exo1) processes stalled replication forks in checkpoint-defective yeast cells. We now identify 14-3-3 proteins as in vivo interaction partners of Exo1, both in yeast and mammalian cells. Yeast 14-3-3-deficient cells fail to induce Mec1-dependent Exo1 hyperphosphorylation and accumulate Exo1-dependent ssDNA gaps at stalled forks, as revealed by electron microscopy. This leads to persistent checkpoint activation and exacerbated recovery defects. Moreover, using DNA bi-dimensional electrophoresis, we show that 14-3-3 proteins promote fork progression under limiting nucleotide concentrations. We propose that 14-3-3 proteins assist in controlling the phosphorylation status of Exo1 and additional unknown targets, promoting fork progression, stability, and restart in response to DNA replication stress.
authors.affiliation: Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
authors.forename: Kim
authors.initials: K
authors.lastname: Engels
authors.forename: Michele
authors.initials: M
authors.lastname: Giannattasio
authors.forename: Marco
authors.initials: M
authors.lastname: Muzi-Falconi
authors.forename: Massimo
authors.initials: M
authors.lastname: Lopes
authors.forename: Stefano
authors.initials: S
authors.lastname: Ferrari
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D004260:DNA Repair; D004261:DNA Replication; D015180:Electrophoresis, Gel, Two-Dimensional; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D017353:Gene Deletion; D057809:HEK293 Cells; D006801:Humans; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D029701:Saccharomyces cerevisiae Proteins; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I