Article
- The EMBO Journal (2008) 27, 2628 - 2637
- doi:10.1038/emboj.2008.184
Published online: 11 September 2008
Subject Categories:
Structural basis for LEAFY floral switch function and similarity with helix-turn-helix proteins
Cécile Hamès1,a, Denis Ptchelkine2,3,a, Clemens Grimm2,b, Emmanuel Thevenon1, Edwige Moyroud1, Francine Gérard4, Jean-Louis Martiel5, Reyes Benlloch1,c, François Parcy1 and Christoph W Müller2,3
- Laboratoire Physiologie Cellulaire Végétale, UMR5168, Centre National de la Recherche Scientifique, Commissariat à l'énergie atomique, Institut National de la Recherche Agronomique, Université Joseph Fourier, Grenoble, France
- European Molecular Biology Laboratory, Grenoble, France
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Heidelberg, Germany
- Unit of Virus Host Cell Interactions, UMR5233 Université Joseph Fourier—European Molecular Biology Laboratory—Centre National de la Recherche Scientifique, Grenoble, France
- TIMC-IMAG Laboratory, Université Joseph Fourier, CNRS UMR5525, INSERM, Grenoble, France
Correspondence to:
François Parcy, Laboratoire Physiologie Cellulaire Végétale, CNRS, UMR5168, CEA, 17 av. des Martyrs, bât. C2, 38054 Grenoble, France. Tel.: +33 438 784 978; Fax: +33 438 784 091; E-mail: francois.parcy@cea.fr
Christoph W Müller, Structural and Computational Biology Unit, EMBL Meyerhofstrasse 1, 69012 Heidelberg, Germany. Tel.: +49 6221 387 8320; Fax: +49 6221 387 519; E-mail: christoph.mueller@embl.de
aThese authors contributed equally to this work
bPresent address: Institut für Biochemie, Biozentrum der Universität, Am Hubland, 97074 Würzburg, Germany
cPresent address: Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
Received 11 April 2008; Accepted 22 August 2008
Abstract
The LEAFY (LFY) protein is a key regulator of flower development in angiosperms. Its gradually increased expression governs the sharp floral transition, and LFY subsequently controls the patterning of flower meristems by inducing the expression of floral homeotic genes. Despite a wealth of genetic data, how LFY functions at the molecular level is poorly understood. Here, we report crystal structures for the DNA-binding domain of Arabidopsis thaliana LFY bound to two target promoter elements. LFY adopts a novel seven-helix fold that binds DNA as a cooperative dimer, forming base-specific contacts in both the major and minor grooves. Cooperativity is mediated by two basic residues and plausibly accounts for LFY's effectiveness in triggering sharp developmental transitions. Our structure reveals an unexpected similarity between LFY and helix-turn-helix proteins, including homeodomain proteins known to regulate morphogenesis in higher eukaryotes. The appearance of flowering plants has been linked to the molecular evolution of LFY. Our study provides a unique framework to elucidate the molecular mechanisms underlying floral development and the evolutionary history of flowering plants.
Keywords:
- crystal structure,
- flower development,
- homeotic genes,
- LEAFY,
- transcriptional regulation
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