An efficient chloramphenicol-resistance marker for Saccharomyces cerevisiae and Escherichia coli.

Chloramphenicol (Cm) was demonstrated to be a suitable selective agent for the plasmid-mediated transformation of haploid and polyploid strains of Saccharomyces cerevisiae. A yeast/Escherichia coli shuttle Cm-resistance (CmR) marker was constructed by inserting the CAT coding sequence from Tn9, and its associated bacterial ribosome-binding site, between a modified yeast ADC1 promoter and CYC1 terminator. When present on a 2 microns-based replicating plasmid, this marker transformed yeast as efficiently as the auxotrophic markers TRP1 and LEU2. When included in an integrating vector, single-copy transformants were formed as efficiently as with LEU2 and HIS3. Industrial yeast strains were transformed with both the replicating and integrating plasmids. The CmR marker could also efficiently transform E. coli. This versatile and efficient performance is currently unique for a yeast dominant marker.