Replication in hydroxyurea: it's a matter of time

Mol Cell Biol. 2007 Sep;27(18):6396-406. doi: 10.1128/MCB.00719-07. Epub 2007 Jul 16.


Hydroxyurea (HU) is a DNA replication inhibitor that negatively affects both the elongation and initiation phases of replication and triggers the "intra-S phase checkpoint." Previous work with budding yeast has shown that, during a short exposure to HU, MEC1/RAD53 prevent initiation at some late S phase origins. In this study, we have performed microarray experiments to follow the fate of all origins over an extended exposure to HU. We show that the genome-wide progression of DNA synthesis, including origin activation, follows the same pattern in the presence of HU as in its absence, although the time frames are very different. We find no evidence for a specific effect that excludes initiation from late origins. Rather, HU causes S phase to proceed in slow motion; all temporal classes of origins are affected, but the order in which they become active is maintained. We propose a revised model for the checkpoint response to HU that accounts for the continued but slowed pace of the temporal program of origin activation.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Cycle Proteins / metabolism
  • Checkpoint Kinase 2
  • DNA Replication / drug effects*
  • DNA, Fungal / biosynthesis*
  • Genome, Fungal
  • Hydroxyurea / pharmacology*
  • Intracellular Signaling Peptides and Proteins
  • Models, Biological
  • Oligonucleotide Array Sequence Analysis
  • Protein Serine-Threonine Kinases / metabolism
  • Replication Origin
  • S Phase / drug effects
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / metabolism
  • Time Factors


  • Cell Cycle Proteins
  • DNA, Fungal
  • Intracellular Signaling Peptides and Proteins
  • Saccharomyces cerevisiae Proteins
  • Checkpoint Kinase 2
  • MEC1 protein, S cerevisiae
  • Protein Serine-Threonine Kinases
  • RAD53 protein, S cerevisiae
  • Hydroxyurea