SPRTN protease and checkpoint kinase 1 cross-activation loop safeguards DNA replication

  • Nat Commun. 2019 Jul 17;10(1):3142. doi: 10.1038/s41467-019-11095-y.
Swagata Halder  1 ,  Ignacio Torrecilla  1 ,  Martin D Burkhalter  2  3 ,  Marta Popović  1  4 ,  John Fielden  1 ,  Bruno Vaz  1 ,  Judith Oehler  1 ,  Domenic Pilger  1 ,  Davor Lessel  5 ,  Katherine Wiseman  1 ,  Abhay Narayan Singh  1 ,  Iolanda Vendrell  1  6 ,  Roman Fischer  6 ,  Melanie Philipp  2  3 ,  Kristijan Ramadan  7
Affiliations
  • 1. Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK.
  • 2. Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
  • 3. Department of Experimental and Clinical Pharmacology and Pharmacogenomics, University of Tübingen, 72074, Tübingen, Germany.
  • 4. Institute Ruder Boškovic, Bijenička Cesta 54, 10000, Zagreb, Croatia.
  • 5. Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany.
  • 6. TDI Mass Spectrometry Laboratory, Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.
  • 7. Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK. [email protected].
PMID: 31316063 DOI: 10.1038/s41467-019-11095-y
Abstract

The SPRTN metalloprotease is essential for DNA-protein crosslink (DPC) repair and DNA replication in vertebrate cells. Cells deficient in SPRTN Protease exhibit DPC-induced replication stress and genome instability, manifesting as premature ageing and Liver Cancer. Here, we provide a body of evidence suggesting that SPRTN activates the ATR-CHK1 phosphorylation signalling cascade during physiological DNA replication by proteolysis-dependent eviction of Chk1 from replicative chromatin. During this process, SPRTN proteolyses the C-terminal/inhibitory part of Chk1, liberating N-terminal Chk1 kinase active fragments. Simultaneously, Chk1 full length and its N-terminal fragments phosphorylate SPRTN at the C-terminal regulatory domain, which stimulates SPRTN recruitment to chromatin to promote unperturbed DNA replication fork progression and DPC repair. Our data suggest that a SPRTN-CHK1 cross-activation loop plays a part in DNA replication and protection from DNA replication stress. Finally, our results with purified components of this pathway further support the proposed model of a SPRTN-CHK1 cross-activation loop.