Figure 5.

HY5 Negatively Regulates FHY3/FAR1-Activated FHY1/FHL Transcription in Yeast and Plant Cells.

(A) and (B) Quantification of β-galactosidase activity in yeast cells harboring the FHY1p-B:LacZ (A) or FHLp-B:LacZ (B) reporter construct and coexpressing AD/AD-FHY3/AD-FAR1 and AD/HY5/AD-HY5 protein combinations shown on the left. Error bars represent sd (n = 4).

(C) Structure of the dual-luciferase reporter construct in which the firefly luciferase (LUC) reporter gene is driven by the wild type or ACE-mutated (both of the ACGT elements were mutated to AaaT) FHY1-B promoter fragment. The Renillia luciferase (REN) reporter gene is controlled by the constitutive 35S promoter. A 105-bp (−101 to +4) NOS minimal promoter (Puente et al., 1996) was inserted upstream of the LUC coding sequence to allow the promoter fragment to drive the LUC reporter gene transcription. Cauliflower mosaic virus terminator (Ter) and the T-DNA left border (LB) and right border (RB) are also indicated.

(D) Relative reporter activity in tobacco cells transiently transformed with the indicated effector and reporter constructs. FHY3 and HY5 are expressed by the 35S:FHY3 and 35S:HY5 effector plasmids (see Methods), respectively. Tobacco leaves were kept in white light for 4 d after infiltration. The relative LUC activities normalized to the REN activity are shown (LUC/REN). Error bars represent sd (n = 3).

[See online article for color version of this figure.]