Abstract
COP9 signalosome (CSN) is a nuclear complex regulating signal transduction in plants and animals. To dissect the function of CSN, we focus on the function of CSN1 subunit. The N-terminal region of CSN1 (CSN1N) possessed a transcriptional repression activity in mammals, and was essential for survival in plants. To understand this mechanism, Yeast Two-Hybrid method was utilized to isolate proteins interacting with CSN1N in Arabidopsis. Here, we isolated a transcription factor containing a predicted structural domain composed of three helixes and two loops. In Arabidopsis, transcription factors with this conserved domain form a novel family. This conservation was preserved in plants, but not in mammals, which suggests that these genes may encode proteins with plant-specific functions. In pull-down assays, this transcription factor, and two others from the family, was shown to directly bind CSN1N. Here, we characterize these transcriptional factors, and discuss their role in CSN regulation.
