Aca1 and Aca2, ATF/CREB activators in Saccharomyces cerevisiae, are important for carbon source utilization but not the response to stress.
In Saccharomyces cerevisiae, the family of ATF/CREB transcriptional regulators consists of a repressor, Acr1 (Sko1), and two activators, Aca1 and Aca2. The AP-1 factor Gen4 does not activate transcription through ATF/CREB sites in vivo even though it binds these sites in vitro. Unlike ATF/CREB activators in other species, Aca1- and Aca2-dependent transcription is not affected by protein kinase A or by stress, and Aca1 and Aca2 are not required for Hog1-dependent salt induction of transcription through an optimal ATF/CREB site. Aca2 is important for a variety of biological functions including growth on nonoptimal carbon sources, and Aca2-dependent activation is modestly regulated by carbon source. Strains lacking Aca1 are phenotypically normal, but overexpression of Aca1 suppresses some defects associated with the loss of Aca2, indicating a functional overlap between Aca1 and Aca2. Acr1 represses transcription both by recruiting the Cyc8-Tup1 corepressor and by directly competing with Aca1 and Aca2 for target sites. Acr1 does not fully account for osmotic regulation through ATF/CREB sites, and a novel Hog1-dependent activator(s) that is not a bZIP protein is required for ATF/CREB site activation in response to high salt. In addition, Acr1 does not affect a number of phenotypes that arise from loss of Aca2. Thus, members of the S. cerevisiae ATF/CREB family have overlapping, but distinct, biological functions and target genes.
Garcia-Gimeno
M A
MA
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Struhl
K
K
D051696:Activating Transcription Factors; D000595:Amino Acid Sequence; D002244:Carbon / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology
C410227:ACA1 protein, S cerevisiae; D051696:Activating Transcription Factors; C410226:CST6 protein, S cerevisiae; D017362:Cyclic AMP Response Element-Binding Protein; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D002244:Carbon