The Ashbya gossypiiEF-1α promoter of the ubiquitously used MX cassettes is toxic to Saccharomyces cerevisiae.
Journal article, 2011

Protein overexpression based on introduction of multiple gene copies is well established. To improve purification or quantification, proteins are typically fused to peptide tags. In Saccharomyces cerevisiae, this has been hampered by multicopy toxicity of the TAP and GFP cassettes used in the global strain collections. Here, we show that this effect is due to the EF-1α promoter in the HIS3MX marker cassette rather than the tags per se. This promoter is frequently used in heterologous marker cassettes, including HIS3MX, KanMX, NatMX, PatMX and HphMX. Toxicity could be eliminated by promoter replacement or exclusion of the marker cassette. To our knowledge, this is the first report of toxicity caused by introduction of a heterologous promoter alone.

Histidine toxicity Protein overexpression HIS3 MX toxicity TAP-tag toxicity


Roja Babazadeh

University of Gothenburg

Soode Moghadas Jafari

Martin Zackrisson

University of Gothenburg

Anders Blomberg

University of Gothenburg

Stefan Hohmann

University of Gothenburg

Jonas Warringer

University of Gothenburg

Marcus Krantz

University of Gothenburg

FEBS letters

1873-3468 (ISSN)

Subject Categories

Cell Biology

Biochemistry and Molecular Biology





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