A novel Mcm1-dependent element in the SWI4, CLN3, CDC6, and CDC47 promoters activates M/G1-specific transcription.

Abstract

We have identified a novel promoter element that confers M/Gl-specific transcription in Saccharomyces cerevisiae. This element, which we call an ECB (early cell cycle box), was first identified in the SWI4 promoter, but it is also present in the promoter of a G 1 cyclin CLN3, as well as in the promoters of three DNA replication genes: CDC6, CDC47, and CDC46. Transcripts from all five of these genes oscillate during the cell cycle and peak at the M/G1 boundary, as do isolated ECB elements in reporter constructs. The ECB element contains an Mcml binding site to which Mcml binds in vitro, and an Mcml-VP16 fusion, which places a constitutive activator on Mcml-binding sites in vivo, can deregulate ECB-containing promoters. Mcml is a transcription factor that is also required for minichromosome maintenance. We provide evidence that the replication defect of mcml mutants can be suppressed by ectopic CDC6 transcription. Periodic expression of SWI4 and CLN3 may be important for cell cycle progression, as we find that these genes are both haploinsufficient and rate limiting for G1 progression. We suggest that ECB-regulated gene products play critical roles in promoting the initiation of S-phase, both by regulating CLN1 and CLN2 transcription and as components of the initiation complex on origins of replication.

Comprehensive Identification of Cell Cycle–regulated Genes of the YeastSaccharomyces cerevisiaeby Microarray Hybridization

“…This cluster has similarities to the CLB2 cluster, except that peak expression is slightly later. Searches of the upstream regions reveal that the majority of these genes contain binding sites for Mcm1p, as was previously shown for some members of the cluster (McInerny et al, 1997). Some, but not all, of these MCM1 sites have nearby sites for SFF (e.g., in FAR1, SPO12, KIN3, and CDC47), although these presumptive SFF sites are of varying quality.…”

“…Some, but not all, of these MCM1 sites have nearby sites for SFF (e.g., in FAR1, SPO12, KIN3, and CDC47), although these presumptive SFF sites are of varying quality. It has been suggested that some of the genes in this cluster are regulated through the "ECB," a variant of the Mcm1p binding site (McInerny et al, 1997).…”

“…In cooperation with an uncloned factor called "Swi five factor" (SFF), it induces the expression of CLB1, CLB2, BUD4, and SWI5 in M (Lydall et al, 1991;Sanders and Herskowitz, 1996). Finally, possibly acting without a partner, it induces transcription of CLN3, SWI4, and CDC6 at the M/G1 boundary (McInerny et al, 1997). The Mcm1p ϩ SFF combination is interesting, because it is somehow activated by Clb2p-Cdc28p, and Mcm1p ϩ SFF then induces further transcription of CLB2.…”

A role for the Pcl9‐Pho85 cyclin–cdk complex at the M/G1 boundary in Saccharomyces cerevisiae

“…The regulation that we have discovered for PCL9 is unique among known cyclins. The G 1 cyclin CLN3, like PCL9, has peak expression at the M/G 1 boundary but is regulated by the Mcm1 protein rather than Swi5 (McInerny et al, 1997).…”

Disruption of Yeast Forkhead-associated Cell Cycle Transcription by Oxidative Stress

“…The major part of this coordination is achieved by the sequential activation of a small number of transcription regulators (reviewed in Mendenhall and Hodge, 1998): MBF (a complex of Mbp1p and Swi6p) and SBF (a complex of Swi4p and Swi6p) are responsible for activating G1 transcription (Koch et al, 1993); Fkh1p and a complex formed by the cooperative promoter binding of Mcm1p and Fkh2p and a later recruitment of Ndd1p are responsible for activating G2/M transcription (Koranda et al, 2000;Kumar et al, 2000;Pic et al, 2000;Hollenhorst et al, 2001); Swi5p and Ace2p, which are themselves expressed during G2/M, are the transcription factors responsible for activating the greater part of the next wave of M/G1 transcription (Dohrmann et al, 1992;Toyn et al, 1997); and Mcm1p, this time alone, is additionally responsible for activating transcription of several other M/G1 genes (McInerny et al, 1997).…”