1. Spd2 assists Spd1 in modulation of RNR architecture but does not regulate deoxynucleotide pools
- Author
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Birthe B. Kragelund, Olaf Nielsen, Antony M. Carr, Christian Holmberg, Ulrik Fahnøe, Katrine Landvad, Oliver Fleck, Ann-Sofie Schreurs, Sebastian S. Broendum, and Rasmus Vejrup-Hansen
- Subjects
QD0415 ,Ribonucleotide reductase ,DNA synthesis ,Biochemistry ,DNA damage ,Protein subunit ,Mutant ,Schizosaccharomyces pombe ,Cell Biology ,Biology ,Nuclear transport ,biology.organism_classification ,Intracellular - Abstract
In yeasts, small intrinsically disordered proteins (IDPs) modulate ribonucleotide reductase (RNR) activity to ensure an optimal supply of dNTPs for DNA synthesis. The Schizosaccharomyces pombe Spd1 protein can directly inhibit the large RNR subunit (R1), import the small subunit (R2) into the nucleus and induce an architectural change in the R1–R2 holocomplex. Here, we report the characterization of Spd2, a protein with sequence similarity to Spd1. We show that Spd2 is a CRL4 Cdt2 -controlled IDP that functions together with Spd1 in the DNA damage response and in modulation of RNR architecture. However, Spd2 does not regulate dNTP pools and R2 nuclear import. Furthermore, deletion of spd2 only weakly suppresses the Rad3 ATR checkpoint dependency of CRL4 Cdt2 mutants. However, when we raised intracellular dNTP pools by inactivation of RNR feedback inhibition, deletion of spd2 could suppress the checkpoint dependency of CRL4 Cdt2 mutant cells to the same extent as deletion of spd1 . Collectively, these observations suggest that Spd1 on its own regulates dNTP pools, whereas in combination with Spd2 it modulates RNR architecture and sensitizes cells to DNA damage.
- Published
- 2014