Koç, AhmetWheeler, Linda J.Mathews, Christopher K.2017-06-192017-06-192003KOÇ, A., Wheeler, L., Mathews, C., & Gary, M. (2003). Hydroxyurea arrests DNA replication by a mechanism that preserves basal dNTP pools . J Biol Chem, (279(1)), 223–0.http://www.jbc.org/content/279/1/223.full.pdfhttps://hdl.handle.net/11616/7112J Biol ChemThe relationship between dNTP levels and DNA synthesis was investigated using factor-synchronized yeast treated with the ribonucleotide reductase inhibitor hydroxyurea (HU). Although HU blocked DNA synthesis and prevented the dNTP pool expansion that normally occurs at G1/S, it did not exhaust the levels of any of the four dNTPs, which dropped to about 80% of G1 levels. When dbf4 yeast that are ts for replication initiation were allowed to preaccumulate dNTPs at 37 °C before being released to 25 °C in the presence of HU, they synthesized 0.3 genome equivalents of DNA and then arrested as dNTPs approached sub-G1 levels. Accumulation of dNTPs at G1/S was not a prerequisite for replication initiation, since dbf4 cells incubated in HU at 25 °C were able to replicate when subsequently switched to 37 °C in the absence of HU. The replication arrest mechanism was not dependent on the Mec1/ Rad53 pathway, since checkpoint-deficient rad53 cells also failed to exhaust basal dNTPs when incubated in HU. The persistence of basal dNTP levels in HU-arrested cells and partial bypass of the arrest in cells that had preaccumulated dNTPs suggest that cells have a mechanism for arresting DNA chain elongation when dNTP levels are not maintained above a critical threshold.eninfo:eu-repo/semantics/openAccessArticle27912230