Photoexcited CRY2 Interacts with CIB1 to Regulate Transcription and Floral Initiation in Arabidopsis

• Published in: Science (American Association for the Advancement of Science) Vol. 322; no. 5907; pp. 1535 - 1539
• Main Authors: Liu, Hongtao, Yu, Xuhong, Li, Kunwu, Klejnot, John, Yang, Hongyun, Lisiero, Dominique, Lin, Chentao
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 05-12-2008; The American Association for the Advancement of Science
• Subjects: Agronomy. Soil science and plant productions; Amino Acid Sequence; Antibodies; Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Basic helix loop helix transcription factors; Basic Helix-Loop-Helix Transcription Factors - chemistry; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Binding sites; Biological and medical sciences; Botany; Cell Nucleus - metabolism; Cellular biology; Chromatin Immunoprecipitation; Cryptochromes; DNA; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Flowers - growth & development; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genetics and breeding of economic plants; Light; Messenger RNA; Molecular Sequence Data; Mutant Proteins - chemistry; Mutant Proteins - metabolism; Photoreceptors; Plant cells; Plants; Plants, Genetically Modified; Promoter Regions, Genetic; Protein Binding; Proteins; Ribonucleic acid; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant - genetics; RNA, Plant - metabolism; Seedlings; Signal Transduction; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Two-Hybrid System Techniques; Yeasts; Helix loop helix structure; Chromatin; Yeast; Photoactivation; Photoreceptor; Floral initiation; Flavoprotein; In vitro; Protein; Arabidopsis thaliana; Messenger RNA; Gene; Cruciferae; Dicotyledones; DNA; Angiospermae; Affinity; Flowering; Spermatophyta; Blue light; Experimental plant; Transcription factor
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1163927

Cryptochromes (CRY) are photolyase-like blue-light receptors that mediate light responses in plants and animals. How plant cryptochromes act in response to blue light is not well understood. We report here the identification and characterization of the Arabidopsis CIB1 (cryptochrome-interacting basic-helix-loop-helix) protein. CIB1 interacts with CRY2 (cryptochrome 2) in a blue light-specific manner in yeast and Arabidopsis cells, and it acts together with additional CIB1-related proteins to promote CRY2-dependent floral initiation. CIB1 binds to G box (CACGTG) in vitro with a higher affinity than its interaction with other E-box elements (CANNTG). However, CIB1 stimulates FT messenger RNA expression, and it interacts with chromatin DNA of the FT gene that possesses various E-box elements except G box. We propose that the blue light-dependent interaction of cryptochrome(s) with CIB1 and CIB1-related proteins represents an early photoreceptor signaling mechanism in plants.