Dif1 is a DNA-damage-regulated facilitator of nuclear import for ribonucleotide reductase.
The control of dNTP concentrations is critical to the fidelity of DNA synthesis and repair. One level of regulation is through subcellular localization of ribonucleotide reductase. In Saccharomyces cerevisiae, the small subunit Rnr2-Rnr4 is nuclear, whereas the large subunit Rnr1 is cytoplasmic. In response to S phase or DNA damage, Rnr2-Rnr4 enters the cytoplasm to bind Rnr1, forming an active complex. We previously reported that Wtm1 anchors Rnr2-Rnr4 in the nucleus. Here, we identify DIF1, which regulates localization of Rnr2-Rnr4. Dif1 binds directly to the Rnr2-Rnr4 complex through a conserved Hug domain to drive nuclear import. Dif1 is both cell-cycle and DNA-damage regulated, the latter of which occurs via the Mec1-Dun1 pathway. In response to DNA damage, Dun1 directly phosphorylates Dif1, which both inactivates and degrades Dif1 and allows Rnr2-Rnr4 to become cytoplasmic. We propose that Rnr2-Rnr4 nuclear localization is achieved by a dynamic combination of Wtm1-mediated nuclear retention to limit export and regulated nuclear import through Dif1.
Harvard Medical School, Department of Genetics, Brigham and Women's Hospital, Center for Genetics and Genomics, Howard Hughes Medical Institute, Boston, MA 02115, USA.
Yang David
YD
Lee
Jun
J
Wang
Joanne
J
Stubbe
Stephen J
SJ
Elledge
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D002453:Cell Cycle; D017124:Conserved Sequence; D004249:DNA Damage; D005800:Genes, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D012262:Ribonucleoside Diphosphate Reductase / Q000378:metabolism; D012264:Ribonucleotide Reductases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D051155:Wnt1 Protein / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; D051155:Wnt1 Protein; D012264:Ribonucleotide Reductases; D012262:Ribonucleoside Diphosphate Reductase; C523202:Rnr4 protein, S cerevisiae; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases