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First published online August 19, 2005; 10.1104/pp.105.065656 Plant Physiology 139:127-137 (2005) © 2005 American Society of Plant Biologists
Activation of a Novel Transcription Factor through Phosphorylation by WIPK, a Wound-Induced Mitogen-Activated Protein Kinase in Tobacco Plants1Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630–0192, Japan
Wound-induced protein kinase (WIPK) is a tobacco (Nicotiana tabacum) mitogen-activated protein kinase known to play an essential role in defense against wounding and pathogens, although its downstream targets have yet to be clarified. This study identified a gene encoding a protein of 648 amino acids, which directly interacts with WIPK, designated as N. tabacum WIPK-interacting factor (NtWIF). The N-terminal region with approximately 250 amino acids showed a high similarity to the plant-specific DNA binding domain, B3, but no other similarity with known proteins. The C terminus of approximately 200 amino acids appeared to be essential for the interaction with WIPK, and a Luciferase-reporter gene assay using Bright Yellow 2 cells indicated the full-length protein to possess trans-activation activity, located to the middle region of approximately 200 amino acids. In vitro phosphorylation assays indicated that WIPK efficiently phosphorylates the full-length protein and the N terminus but not the C terminus. When full-length NtWIF was coexpressed with WIPK in Bright Yellow 2 cells, the Luciferase transcriptional activity increased up to 5-fold that of NtWIF alone, whereas no effect was observed with a kinase-deficient WIPK mutant. Transcripts of NtWIF began to simultaneously accumulate with those of WIPK 30 min after wounding and 1 h after the onset of hypersensitive response upon tobacco mosaic virus infection. These results suggest that NtWIF is a transcription factor that is directly phosphorylated by WIPK, thereby being activated for transcription of target gene(s) involved in wound and pathogen responses.
1 This work was supported by a grant for the Research for the Future from the Japan Society for the Promotion of Science Program (grant no. JSPS–RFTF 00L01604). 2 These authors contributed equally to the paper. 3 Present address: Institut für Phytopathologie und Angewandte Zoologie, Justus-Liebig Universitaet Giessen, D–35392 Giessen, Germany. 4 Present address: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164–6340. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.065656. * Corresponding author; e-mail sano{at}gtc.naist.jp; fax 81–743–72–5659. Received May 15, 2005; returned for revision June 23, 2005; accepted June 24, 2005. This article has been cited by other articles:
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