Calcineurin acts through theCRZ1/TCN1-encoded transcription factor to regulate gene expression in yeast

Abstract

Calcineurin is a conserved Ca²⁺/calmodulin-dependent protein phosphatase that plays a critical role in Ca²⁺ signaling. We describe new components of a calcineurin-mediated response in yeast, the Ca²⁺-induced transcriptional activation ofFKS2, which encodes a β-1,3 glucan synthase. A 24-bp region of the FKS2 promoter was defined as sufficient to confer calcineurin-dependent transcriptional induction on a minimal promoter in response to Ca²⁺ and was named CDRE (forcalcineurin-dependentresponse element). The product ofCRZ1 (YNL027w) was identified as an activator of CDRE-driven transcription. Crz1p contains zinc finger motifs and binds specifically to the CDRE. Genetic analysis revealed that crz1Δ mutant cells exhibit several phenotypes similar to those of calcineurin mutants and that overexpression of CRZ1 in calcineurin mutants suppressed these phenotypes. These results suggest that Crz1p functions downstream of calcineurin to effect multiple calcineurin-dependent responses. Moreover, the calcineurin-dependent transcriptional induction of FKS2 in response to Ca²⁺, α-factor, and Na⁺ was found to require CRZ1. In addition, we found that the calcineurin-dependent transcriptional regulation ofPMR2 and PMC1 required CRZ1. However, transcription of PMR2 and PMC1 was activated by only a subset of the treatments that activated FKS2 transcription. Thus, in response to multiple signals, calcineurin acts through the Crz1p transcription factor to differentially regulate the expression of several target genes in yeast.

Keywords

• S. cerevisiae
• calcineurin
• calcium signaling
• transcriptional activation
• cell wall maintenance
• ion homeostasis