Schizosaccharomyces pombe reporter strains for relative quantitative assessment of heterochromatin silencing

The fission yeast Schizosaccharomyces pombe has been emerging as an important model organism for studying the formation and repression of heterochromatin. To enable simple and relative quantitative assessment of heterochromatin silencing, we have created bioluminescence-based reporter strains. A green-emitting click beetle luciferase (CBG68) gene was inserted within pericentromeric heterochromatin or at the silent mating-type locus via homologous recombination. In the same strains, a red-emitting click beetle luciferase (CBR) gene is expressed from the euchromatic leu1(+) locus and can be used as a reference in dual-colour assays. Our reporter strains are suitable for performing Chroma-Glo™ assays, which can be carried out directly in the culture medium without prior cell lysis and in a multiwell format. Our reporter system reliably reflects the state of chromatin and can be easily adapted for use in high-throughput screening approaches.