Tcn1p/Crz1p, a calcineurin-dependent transcription factor that differentially regulates gene expression in Saccharomyces cerevisiae.
Ca2+ signals regulate gene expression in animal and yeast cells through mechanisms involving calcineurin, a protein phosphatase activated by binding Ca2+ and calmodulin. Tcn1p, also named Crz1p, was identified as a transcription factor in yeast required for the calcineurin-dependent induction of PMC1, PMR1, PMR2A, and FKS2 which confer tolerance to high Ca2+, Mn2+, Na+, and cell wall damage, respectively. Tcn1p was not required for other calcineurin-dependent processes, such as inhibition of a vacuolar H+/Ca2+ exchanger and inhibition of a pheromone-stimulated Ca2+ uptake system, suggesting that Tcn1p functions downstream of calcineurin on a branch of the calcium signaling pathway leading to gene expression. Tcn1p contains three zinc finger motifs at its carboxyl terminus resembling the DNA-binding domains of Zif268, Swi5p, and other transcription factors. When fused to the transcription activation domain of Gal4p, the carboxy terminal domain of Tcn1p directed strong calcineurin-independent expression of PMC1-lacZ and other target genes. The amino-terminal domain of Tcn1p was found to function as a calcineurin-dependent transcription activation domain when fused to the DNA-binding domain of Gal4p. This amino-terminal domain also formed Ca2+-dependent and FK506-sensitive interactions with calcineurin in the yeast two-hybrid assay. These findings suggest that Tcn1p functions as a calcineurin-dependent transcription factor. Interestingly, induction of Tcn1p-dependent genes was found to be differentially controlled in response to physiological Ca2+ signals generated by treatment with mating pheromone and high salt. We propose that different promoters are sensitive to variations in the strength of Ca2+ signals generated by these stimuli and to effects of other signaling pathways.
Matheos
D P
DP
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218 USA.
Kingsbury
T J
TJ
Ahsan
U S
US
Cunningham
K W
KW
D000595:Amino Acid Sequence; D001665:Binding Sites; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D005964:Glucosyltransferases; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010675:Pheromones / Q000494:pharmacology; D053499:Plasma Membrane Calcium-Transporting ATPases; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
C109868:CRZ1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; C085484:PMC1 protein, S cerevisiae; D010675:Pheromones; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D005964:Glucosyltransferases; C095724:GSC2 protein, S cerevisiae; D019703:Calcineurin; D001616:beta-Galactosidase; D053499:Plasma Membrane Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D002118:Calcium