The C-terminal region of the Hot1 transcription factor binds GGGACAAA-related sequences in the promoter of its target genes

Response to hyperosmotic stress in the yeast Saccharomyces cerevisiae involves the participation of the general stress response mediated by Msn2/4 transcription factors and the HOG pathway. One of the transcription factors activated through this pathway is Hot1, which contributes to the control of the expression of several genes involved in glycerol synthesis and flux, or in other functions related to adaptation to adverse conditions. This work provides new data about the interaction mechanism of this transcription factor with DNA. By means of one-hybrid and electrophoretic mobility assays, we demonstrate that the C-terminal region, which corresponds to amino acids 610-719, is the DNA-binding domain of Hot1. We also describe how this domain recognizes sequence 5'-GGGACAAA-3' located in the promoter of gene STL1. The bioinformatics analysis carried out in this work allowed the identification of identical or similar sequences (with up to two mismatches) in the promoter of other Hot1 targets, where central element GGACA was quite conserved among them. Finally, we found that small variations in the sequence recognized by Hot1 may influence its ability to recognize its targets in vivo.