Abstract
After light-induced nuclear translocation, phytochrome photoreceptors interact with and induce rapid phosphorylation and degradation of basic helix-loop-helix transcription factors, such as PHYTOCHROME-INTERACTING FACTOR 3 (PIF3), to regulate gene expression. Concomitantly, this interaction triggers feedback reduction of phytochrome B (phyB) levels. Light-induced phosphorylation of PIF3 is necessary for the degradation of both proteins. We report that this PIF3 phosphorylation induces, and is necessary for, recruitment of LRB [Light-Response Bric-a-Brack/Tramtrack/Broad (BTB)] E3 ubiquitin ligases to the PIF3-phyB complex. The recruited LRBs promote concurrent polyubiqutination and degradation of both PIF3 and phyB in vivo. These data reveal a linked signal-transmission and attenuation mechanism involving mutually assured destruction of the receptor and its immediate signaling partner.
Copyright © 2014, American Association for the Advancement of Science.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Active Transport, Cell Nucleus
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Arabidopsis / genetics
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Arabidopsis / growth & development*
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Arabidopsis / metabolism
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Basic Helix-Loop-Helix Transcription Factors / genetics
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Basic Helix-Loop-Helix Transcription Factors / metabolism*
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Cell Nucleus / metabolism
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Cullin Proteins / metabolism*
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Gene Expression Regulation, Plant
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HeLa Cells
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Humans
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Light Signal Transduction*
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Phosphorylation
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Phytochrome B / metabolism*
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Polyubiquitin / metabolism
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Proteolysis
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Ubiquitination*
Substances
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Arabidopsis Proteins
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Basic Helix-Loop-Helix Transcription Factors
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Cullin Proteins
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LRB1 protein, Arabidopsis
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LRB2 protein, Arabidopsis
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LRB3 protein, Arabidopsis
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Nuclear Proteins
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PHYB protein, Arabidopsis
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PIF3 protein, Arabidopsis
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Polyubiquitin
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Phytochrome B