The pachytene checkpoint in Saccharomyces cerevisiae requires the Sum1 transcriptional repressor

AUTOR(ES)

Lindgren, Anne

FONTE

Oxford University Press

RESUMO

Saccharomyces cerevisiae mutants that fail to complete meiotic recombination are blocked by the RAD17/RAD24/MEC1 checkpoint signaling pathway in pachytene when early sporulation genes are expressed. Middle genes are not activated in checkpoint-arrested cells because the Ndt80 transcription factor is inhibited. We find that the pachytene checkpoint requires Sum1, a transcriptional repressor that recognizes a subset of Ndt80-binding sites. Mutants lacking Sum1 or Rad17 partially bypass the block to the nuclear divisions but do not form spores, while mutants lacking both Sum1 and Rad17 completely bypass the block and form morphologically normal spores. The level of Sum1 protein decreases as middle genes are expressed, and this decrease is blocked in checkpoint-arrested cells. These data suggest that Sum1 levels are regulated by the checkpoint and that progression of the meiotic divisions and spore differentiation can be differentially controlled by competition of the Sum1 repressor and Ndt80 activator for occupancy at key middle promoters.

Documentos Relacionados

• Role of Ndt80, Sum1, and Swe1 as Targets of the Meiotic Recombination Checkpoint That Control Exit from Pachytene and Spore Formation in Saccharomyces cerevisiae
• Sum1-1: A Suppressor of Silencing Defects in Saccharomyces Cerevisiae
• Xbp1, a stress-induced transcriptional repressor of the Saccharomyces cerevisiae Swi4/Mbp1 family.
• The sum1-1 mutation affects silent mating-type gene transcription in Saccharomyces cerevisiae.
• Nrg1 Is a Transcriptional Repressor for Glucose Repression of STA1 Gene Expression in Saccharomyces cerevisiae