Plant Cell email content delivery
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
 QUICK SEARCH:   [advanced]


     


Plant Cell Advance Online Publication
Published on February 10, 2005; 10.1105/tpc.104.030205


This Article
Right arrow Full Text - TPC Advance Online Pub. (PDF)
Right arrow All Versions of this Article:
17/3/804    most recent
tpc.104.030205v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Yang, J.
Right arrow Articles by Wang, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Yang, J.
Right arrow Articles by Wang, H.
Agricola
Right arrow Articles by Yang, J.
Right arrow Articles by Wang, H.

Received December 13, 2004
Accepted December 21, 2004

Light Regulates COP1-Mediated Degradation of HFR1, a Transcription Factor Essential for Light Signaling in Arabidopsis

Jianping Yang 1, Rongcheng Lin 1, James Sullivan 2, Ute Hoecker 3, Bolin Liu 1, Ling Xu 1, Xing Wang Deng 2, and Haiyang Wang 1*

1 Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853
2 Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520
3 Department of Plant Developmental and Molecular Biology, Heinrich-heine-Universitaet, D-40225 Duesseldorf, Germany

* To whom correspondence should be addressed. E-mail: hw75{at}cornell.edu.

Arabidopsis thaliana seedlings undergo photomorphogenesis in the light and etiolation in the dark. Long Hypocotyl in Far-Red 1 (HFR1), a basic helix-loop-helix transcription factor, is required for both phytochrome A-mediated far-red and cryptochrome 1-mediated blue light signaling. Here, we report that HFR1 is a short-lived protein in darkness and is degraded through a 26S proteasome-dependent pathway. Light, irrespective of its quality, enhances HFR1 protein accumulation via promoting its stabilization. We demonstrate that HFR1 physically interacts with Constitutive Photomorphogenesis 1 (COP1) and that COP1 exhibits ubiquitin ligase activity toward HFR1 in vitro. In addition, we show that COP1 is required for degradation of HFR1 in vivo. Furthermore, plants overexpressing a C-terminal 161-amino acid fragment of HFR1 (CT161) display enhanced photomorphogenesis, suggesting an autonomous function of CT161 in promoting light signaling. This truncated HFR1 gene product is more stable than the full-length HFR1 protein in darkness, indicating that the COP1-interacting N-terminal portion of HFR1 is essential for COP1-mediated destabilization of HFR1. These results suggest that light enhances HFR1 protein accumulation by abrogating COP1-mediated degradation of HFR1, which is necessary and sufficient for promoting light signaling. Additionally, our results substantiate the E3 ligase activity of COP1 and its critical role in desensitizing light signaling.







HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
ASPB Publications THE PLANT CELL PLANT PHYSIOLOGY
Copyright © 2005 by the American Society of Plant Biologists