Document Detail

Photoactivated phytochromes interact with HEMERA and promote its accumulation to establish photomorphogenesis in Arabidopsis.
MedLine Citation:
PMID:  22895253     Owner:  NLM     Status:  MEDLINE    
Plant development is profoundly regulated by ambient light cues through the red/far-red photoreceptors, the phytochromes. Early phytochrome signaling events include the translocation of phytochromes from the cytoplasm to subnuclear domains called photobodies and the degradation of antagonistically acting phytochrome-interacting factors (PIFs). We recently identified a key phytochrome signaling component, HEMERA (HMR), that is essential for both phytochrome B (phyB) localization to photobodies and PIF degradation. However, the signaling mechanism linking phytochromes and HMR is unknown. Here we show that phytochromes directly interact with HMR to promote HMR protein accumulation in the light. HMR binds more strongly to the active form of phytochromes. This interaction is mediated by the photosensory domains of phytochromes and two phytochrome-interacting regions in HMR. Missense mutations in either HMR or phyB that alter the phytochrome/HMR interaction can also change HMR levels and photomorphogenetic responses. HMR accumulation in a constitutively active phyB mutant (YHB) is required for YHB-dependent PIF3 degradation in the dark. Our genetic and biochemical studies strongly support a novel phytochrome signaling mechanism in which photoactivated phytochromes directly interact with HMR and promote HMR accumulation, which in turn mediates the formation of photobodies and the degradation of PIFs to establish photomorphogenesis.
Rafaelo M Galvão; Meina Li; Sonya M Kothadia; Jonathan D Haskel; Peter V Decker; Elise K Van Buskirk; Meng Chen
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Genes & development     Volume:  26     ISSN:  1549-5477     ISO Abbreviation:  Genes Dev.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-08-16     Completed Date:  2012-10-29     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  8711660     Medline TA:  Genes Dev     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1851-63     Citation Subset:  IM    
Department of Biology, Duke University, Durham, North Carolina 27708, USA.
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MeSH Terms
Arabidopsis / genetics,  metabolism*
Arabidopsis Proteins / genetics,  metabolism*
Phytochrome / metabolism*
Protein Binding
Protein Structure, Tertiary
Signal Transduction
Grant Support
Reg. No./Substance:
0/Arabidopsis Proteins; 11121-56-5/Phytochrome

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