A distinct gene expression program is regulated by a specific
phosphorylated form of the transcription factor Pho4.
Dennis
Wykoff, Michael Springer, Nicole Miller, Erin O'Shea
Biochemistry/Biophysics, UCSF/HHMI, 513 Parnassus Ave, San Francisco, CA
94143-0448, USA
In high phosphate growth medium, the budding yeast
transcription factor Pho4 is phosphorylated on four critical residues by
the cyclin-CDK complex Pho80-Pho85. This phosphorylation leads to the
inhibition of both its nuclear localization and its activity. We show
that in intermediate phosphate medium, a form of Pho4 phosphorylated on
one of the four sites accumulates in the nucleus and activates
transcription of a subset of phosphate responsive genes. Differential
phosphorylation may help to explain how a small number of transcription
factors can generate complex patterns of gene regulation by responding
to different levels of stimuli.
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