CLB5-dependent activation of late replication origins in S. cerevisiae

Mol Cell. 1998 Aug;2(2):173-82. doi: 10.1016/s1097-2765(00)80127-6.


Replication origins in chromosomes are activated at specific times during the S phase. We show that the B-type cyclins are required for proper execution of this temporal program. clb5 cells activate early origins but not late origins, explaining the previously described long clb5 S phase. Origin firing appears normal in cIb6 mutants. In clb5 clb6 double mutant cells, the late origin firing defect is suppressed, accounting for the normal duration of the phase despite its delayed onset. Therefore, Clb5p promotes the timely activation of early and late origins, but Clb6p can activate only early origins. In clb5 clb6 mutants, the other B-type cyclins (Clb1-4p) promote an S phase during which both early and late replication origins fire.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Chromosomes, Fungal / genetics
  • Cyclin B*
  • Cyclins / genetics
  • Cyclins / metabolism*
  • DNA Replication / genetics
  • DNA, Fungal / biosynthesis
  • DNA, Fungal / genetics
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Kinetics
  • Models, Biological
  • Mutation
  • Replication Origin*
  • S Phase / genetics
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*


  • CLB5 protein, S cerevisiae
  • CLB6 protein, S cerevisiae
  • Cyclin B
  • Cyclins
  • DNA, Fungal
  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins