A new inducible protein expression system in fission yeast based on the glucose-repressed inv1 promoter.

Studies of the fission yeast Schizosaccharomyces pombe have made major contributions towards understanding cell-cycle control and many other important aspects of cell biology. A series of pREP expression vectors that utilize the thiamine-repressible nmt1 promoter are used routinely to manipulate the expression of genes in fission yeast. A shortcoming of the nmt1 promoter is that it is very slowly induced following removal of thiamine from the growth medium, requiring approx. 16h for full induction. Invertase, an enzyme responsible for sucrose metabolism, is regulated transcriptionally by glucose derepression in S. pombe. Using the inv1 promoter, we have developed the pINV1 set of inducible protein expression vectors. A shift from glucose to sucrose-based culture medium leads to a very rapid induction of the inv1 promoter. Genes that are regulated by the inv1 promoter are fully induced within 1h of the shift to sucrose-based medium. The pINV1 vectors utilize a simple induction protocol and enable studies in fission yeast requiring tight and rapid regulation of protein synthesis.