Global and specific transcriptional repression by the histone H3
amino terminus in budding yeast.
Randall Morse (1), Nevin
Sabet (1), Fumin Tong (1), Mitchell Smith (2)
(1) Molecular
Genetics, Wadsworth Center, 120 New Scotland Ave, Albany , NY 12054,
USA; (2) Dept. of Microbiology, Univ. of Virginia School of Medicine,
Charlottesville, VA 22908
The yeast CHA1 promoter is activated
in the presence of serine or threonine. Its activation requires the
Cha4p activator, and results in perturbation of a nucleosome that
incorporates the TATA element under non-inducing conditions. We have
found that in yeast lacking the amino terminus of histone H3, the
promoter is constitutively active and the chromatin concomitantly
perturbed. This derepression occurs in the absence of elevated
intracellular levels of serine or threonine and requires the primary
activator of this promoter, Cha4p, thereby implicating the H3 amino
terminus in a mechanism that prevents this activator from turning on
CHA1 transcription in the absence of inducer. We also present the
results of a microarray experiment showing that the H3 amino terminus
has a substantial repressive effect on a genome-wide scale.
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