FIG. 8.

Model of the alternative mechanisms of nucleosome-dependent transcriptional activation of yeast HIS7 initiated by two different transcription factors. +ade/+aa, Growth in the presence of adenine and amino acids, that is, without any acid starvation; +ade/−aa, growth in presence of adenine but without amino acids, that is, with amino acid starvation; −ade/+aa, growth without adenine but in the presence of amino acids, that is, with purine starvation. Dark circles represent positioned nucleosomes with strong DNA-histone interactions.