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CDK phosphorylation of a novel NLS-NES module distributed between two subunits of the Mcm2-7 complex prevents chromosomal rereplication.

Cyclin-dependent kinases (CDKs) use multiple mechanisms to block reassembly of prereplicative complexes (pre-RCs) at replication origins to prevent inappropriate rereplication. In Saccharomyces cerevisiae, one of these mechanisms promotes the net nuclear export of a pre-RC component, the Mcm2-7 complex, during S, G2, and M phases. Here we identify two partial nuclear localization signals (NLSs) on Mcm2 and Mcm3 that are each necessary, but not sufficient, for nuclear localization of the Mcm2-7 complex. When brought together in cis, however, the two partial signals constitute a potent NLS, sufficient for robust nuclear localization when fused to an otherwise cytoplasmic protein. We also identify a Crm1-dependent nuclear export signal (NES) adjacent to the Mcm3 NLS. Remarkably, the Mcm2-Mcm3 NLS and the Mcm3 NES are sufficient to form a transport module that recapitulates the cell cycle-regulated localization of the entire Mcm2-7 complex. Moreover, we show that CDK regulation promotes net export by phosphorylation of the Mcm3 portion of this module and that nuclear export of the Mcm2-7 complex is sufficient to disrupt replication initiation. We speculate that the distribution of partial transport signals among distinct subunits of a complex may enhance the specificity of protein localization and raises the possibility that previously undetected distributed transport signals are used by other multiprotein complexes.

Pubmed ID: 16093348


  • Liku ME
  • Nguyen VQ
  • Rosales AW
  • Irie K
  • Li JJ


Molecular biology of the cell

Publication Data

October 29, 2005

Associated Grants

  • Agency: NCI NIH HHS, Id: 1 F31 CA110268-01
  • Agency: NIGMS NIH HHS, Id: 1 R25 GM56847
  • Agency: NIGMS NIH HHS, Id: R01 GM59704
  • Agency: NCI NIH HHS, Id: T32 CA09270

Mesh Terms

  • Amino Acid Sequence
  • CDC28 Protein Kinase, S cerevisiae
  • Cell Cycle
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • Chromosomes, Fungal
  • DNA Replication
  • DNA-Binding Proteins
  • Fungal Proteins
  • Karyopherins
  • Minichromosome Maintenance Complex Component 3
  • Minichromosome Maintenance Complex Component 4
  • Minichromosome Maintenance Complex Component 6
  • Minichromosome Maintenance Complex Component 7
  • Molecular Sequence Data
  • Nuclear Localization Signals
  • Nuclear Proteins
  • Phosphorylation
  • Protein Subunits
  • Protein Transport
  • Receptors, Cytoplasmic and Nuclear
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins