Expression of a yeast glycolytic gene is subject to dosage limitation

The Saccharomyces cerevisiae pyruvate kinase-encoding gene (PYK1) has been transformed back into yeast using a derivative of the multicopy vector, pJDB207. High levels of PYK1 expression in these transformants are limited by at least two separate mechanisms. Pyruvate kinase assays and polysome analyses demonstrate that the translation of the PYK1 mRNA is inhibited as its abundance increases. The abundance of the PYK1 mRNA per gene copy also decreases as the copy number of the PYK1 gene increases. This is the first report which demonstrates that a eukaryotic glycolytic gene is subject to dosage limitation at the translational level.