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Repressing Gene Transcription by Redirecting Cellular Machinery with Chemical Epigenetic Modifiers
Published on: September 20, 2018
Aux/IAA proteins contain a potent transcriptional repression domain
Shiv B Tiwari1, Gretchen Hagen, Tom J Guilfoyle
1Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA.
Abstract:
Aux/IAA proteins are short-lived nuclear proteins that repress expression of primary/early auxin response genes in protoplast transfection assays. Repression is thought to result from Aux/IAA proteins dimerizing with auxin response factor (ARF) transcriptional activators that reside on auxin-responsive promoter elements, referred to as AuxREs. Most Aux/IAA proteins contain four conserved domains, designated domains I, II, III, and IV. Domain II and domains III and IV play roles in protein stability and dimerization, respectively. A clear function for domain I had not been established. Results reported here indicate that domain I in Aux/IAA proteins is an active repression domain that is transferable and dominant over activation domains. An LxLxL motif within domain I is important for conferring repression. The dominance of Aux/IAA repression domains over activation domains in ARF transcriptional activators provides a plausible explanation for the repression of auxin response genes via ARF-Aux/IAA dimerization on auxin-responsive promoters.
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