The Schizosaccharomyces pombe spqM gene is a new member of the Qm transcription factor family

The Qm family of proteins, which are found in a wide variety of species such as budding yeast, plants and humans, are believed to play a role in gene expression. Here, we report the isolation of a gene, spqM, from the fission yeast Schizosaccharomyces pombe whose deduced amino-acid sequence shared 71.6 to 61.36% identity with members of the Qm family. The high degree of conservation of the Qm members suggest that they were selectively conserved, because of an important biological role     

Regulation of the yeast metallothionein gene

To study regulation of the yeast CUP1 gene, we have employed plasmids containing the CUP1 regulatory sequences fused to the Escherichia coli galK gene. A comparison of galK expression from low- and high-copy-number CUP1/galK fusion plasmids demonstrated that both basal and induced levels of galactokinase (GalK) increase proportionately with plasmid copy number. Host strains with an amplified, single or deleted CUP1 locus were compared to look for effects of chromosomal CUP1 gene dosage on expression from the episomal CUP1 promoter. Basal GalK levels are similar in CUP1R and cupls hosts, but can be induced to higher levels in the cup1s than the CUP1R host. In contrast, in a strain deleted for the chromosomal copy of CUP1, synthesis of GalK is constitutive but can be induced to yet higher levels by copper. A hybrid vector, placing the CUP1 coding sequence under the control of a constitutive promoter, was constructed. Introduction of this hybrid CUP1 gene into the deletion host containing the CUP1/galK plasmid restores regulation. Thus, metallothionein, in trans, can effect repression of the CUP1 promoter. The possible roles of metallothionein and free copper in CUP1 regulation are discussed.