Modules for cloning-free chromatin tagging in Saccharomyces cerevisae.

We describe a straightforward two-step PCR-based method to insert arrays of lac or tet operators (lacO or tetO) at specific loci in the budding yeast genome. The method entails insertion of a marker generated by PCR with classical long primers recognizing the locus of interest, followed by the replacement of this marker by a linearized plasmid bearing an array of lacI- or tetR-binding motifs. Using this technique, loci located either in the yeast genome or on yeast artificial chromosomes can be efficiently tagged. We provide a set of plasmids with different markers for cloning-free integration of lacO or tetO repeats into the yeast genome.