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Limiting replication initiation factors execute the temporal programme of origin firing in budding yeast

Davide Mantiero, Amanda Mackenzie, Anne Donaldson, Philip Zegerman

Author Affiliations

  1. Davide Mantiero1,
  2. Amanda Mackenzie2,
  3. Anne Donaldson2 and
  4. Philip Zegerman (p.zegerman{at}gurdon.cam.ac.uk)*,1
  1. 1 Department of Zoology, Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Cambridge, UK
  2. 2 Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen, UK
  1. * Department of Zoology, Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Cambridge CB2 1QN, UK. Tel.: +44 1223 334132; Fax: +44 1223 334089; E‐mail: p.zegerman{at}gurdon.cam.ac.uk

Abstract

Eukaryotic chromosomes are replicated from multiple origins that initiate throughout the S‐phase of the cell cycle. Why all origins do not fire simultaneously at the beginning of S‐phase is not known, but two kinase activities, cyclin‐dependent kinase (CDK) and Dbf4‐dependent kinase (DDK), are continually required throughout the S‐phase for all replication initiation events. Here, we show that the two CDK substrates Sld3 and Sld2 and their binding partner Dpb11, together with the DDK subunit Dbf4 are in low abundance in the budding yeast, Saccharomyces cerevisiae. Over‐expression of these factors is sufficient to allow late firing origins of replication to initiate early and together with deletion of the histone deacetylase RPD3, promotes the firing of heterochromatic, dormant origins. We demonstrate that the normal programme of origin firing prevents inappropriate checkpoint activation and controls S‐phase length in budding yeast. These results explain how the competition for limiting DDK kinase and CDK targets at origins regulates replication initiation kinetics during S‐phase and establishes a unique system with which to investigate the biological roles of the temporal programme of origin firing.

  • Received July 21, 2011.
  • Accepted October 18, 2011.