Functional dissection of the transactivation domain of interferon regulatory factor-1.
Interferon regulatory factor-1 (IRF-1), a putative tumor suppressor protein, is a transcriptional mediator of interferon-responsive signaling pathways that are involved in antiviral defense, apoptosis, immune response, and cell growth regulation. To delineate the IRF-1 domain responsible for transactivation, we performed a detailed deletion analysis of IRF-1. We found that the amino acid segment 217-260 was necessary and sufficient for transactivation. The structure of this region was predicted to be loop-helix-loop-sheet using the program PHD. Further studies indicated that casein kinase II and protein kinase C sites on each of the two loops are not important for transactivation, and a region containing amino acids 233-255 comprises the core activation domain. To verify the physiological role of segment 233-255, we constructed an IRF-1 deletion mutant lacking these amino acids and examined it using IRF-1 transactivation assay, fluorescence-activated cell sorting, and in situ beta-galactosidase staining techniques. From the results of these studies, we conclude that the amino acid segment 233-255 of IRF-1 comprises the core activation domain required for the physiological functions of IRF-1.
Kim
Eun-Joo
EJ
Department of Bioscience and Biotechnology/Institute of Bioscience, Sejong University, 98 Kunja-dong, Kwangjin-gu, Seoul 143-747, Republic of Korea.
Park
Chong-Ho
CH
Park
Jong-Sup
JS
Um
Soo-Jong
SJ
D016475:3T3 Cells; D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D006801:Humans; D050856:Interferon Regulatory Factor-1; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D010750:Phosphoproteins; D015534:Trans-Activators