2؉ . Analysis of crz1⌬ cells established Crz1p as the major effector of calcineurin-regulated gene expression in yeast. We identified the Crz1p-binding site as 5-GNG-GC(G/T)CA-3 by in vitro site selection. A similar sequence, 5-GAGGCTG-3, was identified as a common sequence motif in the upstream regions of calcineurin/ Crz1p-dependent genes. This finding is consistent with direct regulation of these genes by Crz1p.

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The reduction of acetate ester synthesis by aeration and the addition of unsaturated fatty acids to the medium has been reported to be the result of the reduction in alcohol acetyltransferase (AATase) activity induced by inhibition of this enzyme. However, regulation of the AATase gene ATF1 has not been reported. In this study, ATF1 gene expression was studied by Northern analysis, and the results showed that the ATF1 gene was repressed both by aeration and by unsaturated fatty acids. The results also showed that the reduction of AATase activity is closely related to the degree of repression of ATF1 mRNA, which suggested that the gene repression is the primary means of reducing AATase activity in vivo. Using the Escherichia coli lacZ gene as a reporter gene, it was shown that a 150-bp fragment of the 5 flanking sequence played a major role in the repression by aeration and unsaturated fatty acid addition.

It is thought that the FLO8 gene encodes a transcriptional activator of the dominant flocculation gene FLO1 in Saccharomyces cerevisiae. To determine other genes which are regulated by FLO8, a detailed comparison of the transcripts from the FLO8 and Deltaflo8 strains was carried out. In addition to the FLO1 gene, it was found that transcription of the FLO11 and STA1 genes is positively regulated by FLO8. In flo8 strains, not only transcripts of the FLO11, STA1, and FLO1 genes but also invasive growth, extracellular glucoamylase production, and flocculation were undetected. From these results, it is suggested that FLO8 regulates these characteristics via the transcriptional regulation of the FLO11, STA1, and FLO1 genes.

No abstract