Molecular analysis of the promoter region of the hexokinase 2 gene of Saccharomyces cerevisiae.

lacZ fusions of the hexokinase 2 gene promoter were constructed and a deletion analysis was performed in order to identify the cis-acting regulatory elements of the promoter that controls hexokinase 2 gene expression. Expression of the hexokinase 2 gene is induced by glucose and around 40-fold repressed by ethanol. This repression seems to be mediated mainly by a repression element located within the coding region of the hexokinase 2 gene, between +39 and +404 bp from the ATG start codon. A second repressing element for ethanol growing cells was located between -455 bp and -254 bp. A synergistic effect on repression of transcription, when ethanol is the carbon source used for growth, was demonstrated by experiments in which both repressing elements were simultaneously removed. The finding of regulatory sequences in the coding region of the hexokinase 2 gene stimulates a search for regulatory elements in the coding region of other yeast genes.