PT  - JOURNAL ARTICLE
AU  - Chattopadhyay, Sudip
AU  - Ang, Lay-Hong
AU  - Puente, Pilar
AU  - Deng, Xing-Wang
AU  - Wei, Ning
TI  - Arabidopsis bZIP Protein HY5 Directly Interacts with Light-Responsive Promoters in Mediating Light Control of Gene Expression
AID  - 10.1105/tpc.10.5.673
DP  - 1998 May 01
TA  - The Plant Cell
PG  - 673--683
VI  - 10
IP  - 5
4099  - http://www.plantcell.org/content/10/5/673.short
4100  - http://www.plantcell.org/content/10/5/673.full
SO  - Plant Cell1998 May 01; 10
AB  - The Arabidopsis HY5 gene has been defined genetically as a positive regulator of photomorphogenesis and recently has been shown to encode a basic leucine zipper type of transcription factor. Here, we report that HY5 is constitutively nuclear localized and is involved in light regulation of transcriptional activity of the promoters containing the G-box, a well-characterized light-responsive element (LRE). In vitro DNA binding studies suggested that HY5 can bind specifically to the G-box DNA sequences but not to any of the other LREs present in the light-responsive promoters examined. High-irradiance light activation of two synthetic promoters containing either the consensus G-box alone or the G-box combined with the GATA motif (another LRE) and the native Arabidopsis ribulose bisphosphate carboxylase small subunit gene RBCS-1A promoter, which has an essential copy of the G-box, was significantly compromised in the hy5 mutant. The hy5 mutation's effect on the high-irradiance light activation of gene expression was observed in both photosynthetic and nonphotosynthetic tissues. Furthermore, the characteristic phytochrome-mediated red light– and farred light–reversible low-fluence induction of the G-box–containing promoters was diminished specifically in hy5 plants. These results suggest that HY5 may interact directly with the G-box in the promoters of light-inducible genes to mediate light-controlled transcriptional activity.