High functional overlap between MluI cell-cycle box binding factor and Swi4/6 cell-cycle box binding factor in the G1/S transcriptional program in Saccharomyces cerevisiae.
In budding yeast, many genes are induced early in the cell cycle. Induction of these genes has been predominantly attributed to two transcription factors, Swi4-Swi6 (SBF) and Mbp1-Swi6 (MBF). Swi4 and Mbp1 are related DNA-binding proteins with dissimilar target sequences. For most G1/S-regulated genes that we tested in a cdc20 block-release protocol for cell-cycle synchronization, removal of both Swi4 and Mbp1 was necessary and sufficient to essentially eliminate cell-cycle-regulated expression. Detectable SBF or MBF binding sites (SCBs or MCBs) in the promoters or available genome-wide promoter occupancy data do not consistently explain this functional overlap. The overlapping ability of these transcription factors to regulate many promoters with very similar cell-cycle kinetics may provide robustness to the G1/S transcriptional response, but poses a puzzle with respect to promoter-transcription factor specificity. In addition, for some genes, deletion of Mbp1 or Swi4 enhances transcription, suggesting that these factors can also function as transcriptional repressors. Finally, we observe residual G1/S transcriptional regulation in the absence of Swi4 and Mbp1.
Bean
James M
JM
Rockefeller University, New York, New York 10021, USA.
Siggia
Eric D
ED
Cross
Frederick R
FR
D001665:Binding Sites / Q000235:genetics; D015152:Blotting, Northern; D002453:Cell Cycle / Q000235:genetics; D004268:DNA-Binding Proteins; D016193:G1 Phase / Q000235:genetics; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*
D004268:DNA-Binding Proteins; C083209:MBP1 protein, S cerevisiae; D012333:RNA, Messenger; C062214:SWI4 protein, S cerevisiae; C075111:SWI6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors