Identification of an upstream activation sequence and other cis-acting elements required for transcription of COX6 from Saccharomyces cerevisiae.

Abstract

Transcription of Saccharomyces cerevisiae COX6, the nuclear gene for subunit VI

Release of two Saccharomyces cerevisiae cytochrome genes, COX6 and CYC1, from glucose repression requires the SNF1 and SSN6 gene products.

“…address the question, we studied COX6, (25,26) and CYCI (11), the genes that encode cytochrome c oxidase subunit VI and iso-1-cytochrome c, respectively. Previous studies demonstrated that the transcription of both genes is glucose repressible in conjunction with the product of the HAP2 gene (11,23). We report here that SNFI and SSN6 are also required for the release from glucose repression of COX6 and CYC1 and that they affect the transcription of these genes in a manner analogous to the way that they regulate SUC2.…”

“…To corroborate these observations, we transformed both strains with a high-copy-number COX6-lacZ fusion plasmid, pMC61L (23,24), that has 1.5 kilobase pairs of the COX6 upstream DNA and the first 21 codons of COX6 fused to the coding region of the Escherichia coli lacZ gene encoding P-galactosidase. Expression of the COX6-lacZ fusion gene carried on this plasmid is glucose repressible and requires heme and HAP2 in a way that mimics that of the copy of COX6 carried on the chromosome (23).…”

“…It affects the activity of some enzymes and the synthesis of others (6-8, 13). For many genes, the effect of glucose repression on synthesis operates at the level of transcription (18,22) and is mediated by upstream cis-acting sites, i.e., upstream activation sequence elements (10,18,21,23).Through the isolation of nonrepressible and nonderepressible mutants and their suppressors, it has been possible to gain initial insight into the genetic regulation of glucose repression. Of the dozen or so genes so far implicated in glucose repression (1, 6-9, 13, 19), some of the best understood are SNFJ (CA TI, CCRI) and SSN6 (CYC8).…”

“…It affects the activity of some enzymes and the synthesis of others (6-8, 13). For many genes, the effect of glucose repression on synthesis operates at the level of transcription (18,22) and is mediated by upstream cis-acting sites, i.e., upstream activation sequence elements (10,18,21,23).…”

“…Expression of the COX6-lacZ fusion gene carried on this plasmid is glucose repressible and requires heme and HAP2 in a way that mimics that of the copy of COX6 carried on the chromosome (23). Transformant cells were grown as described above, and P-galactosidase activity was measured 3 h after the shift into repressing or derepressing media.…”