OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 148/2/981    most recent pp.108.120436v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Lin, R. Articles by Wang, H. Search for Related Content PubMed PubMed Citation Articles by Lin, R. Articles by Wang, H. Agricola Articles by Lin, R. Articles by Wang, H.

ENVIRONMENTAL STRESS AND ADAPTATION TO STRESS

Discrete and Essential Roles of the Multiple Domains of Arabidopsis FHY3 in Mediating Phytochrome A Signal Transduction^{1,[C],[W],[OA]}

Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853 (R.L., Y.T., H.-J.P., L.D., C.B., H.Y.); and College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310029, People's Republic of China (Y.T., P.F.)

Phytochrome A is the primary photoreceptor for mediating various far-red light-induced responses in higher plants. We recently showed that Arabidopsis (Arabidopsis thaliana) FAR-RED ELONGATED HYPOCOTYL3 (FHY3) and FAR-RED-IMPAIRED RESPONSE1 (FAR1), a pair of homologous proteins sharing significant sequence homology to Mutator-like transposases, act as novel transcription factors essential for activating the expression of FHY1 and FHL (for FHY1-like), whose products are required for light-induced phytochrome A nuclear accumulation and subsequent light responses. FHY3, FAR1, and Mutator-like transposases also share a similar domain structure, including an N-terminal C2H2 zinc finger domain, a central putative core transposase domain, and a C-terminal SWIM motif (named after SWI2/SNF and MuDR transposases). In this study, we performed a promoter-swapping analysis of FHY3 and FAR1. Our results suggest that the partially overlapping functions of FHY3 and FAR1 entail divergence of their promoter activities and protein subfunctionalization. To gain a better understanding of the molecular mode of FHY3 function, we performed a structure-function analysis, using site-directed mutagenesis and transgenic approaches. We show that the conserved N-terminal C2H2 zinc finger domain is essential for direct DNA binding and biological function of FHY3 in mediating light signaling, whereas the central core transposase domain and C-terminal SWIM domain are essential for the transcriptional regulatory activity of FHY3 and its homodimerization or heterodimerization with FAR1. Furthermore, the ability to form homodimers or heterodimers largely correlates with the transcriptional regulatory activity of FHY3 in plant cells. Together, our results reveal discrete roles of the multiple domains of FHY3 and provide functional support for the proposition that FHY3 and FAR1 represent transcription factors derived from a Mutator-like transposase(s).

² These authors contributed equally to the article.

³ Present address: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China.

⁴ Present address: Department of Biology, Indiana University, Bloomington, IN 47405.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Haiyang Wang (hw75{at}cornell.edu).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.120436

^* Corresponding author; e-mail hw75{at}cornell.edu.

Received April 3, 2008; accepted August 15, 2008; published August 20, 2008.