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| Phototropin LOV domains exhibit distinct roles in regulating photoreceptor function |
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| Author(s): Christie JM, Swartz TE, Bogomolni RA, Briggs WR |
| Source: PLANT JOURNAL Volume: 32 Issue: 2 Pages: 205-219 Published: OCT 2002 |
| Times Cited: 95 References: 56 |
| Abstract: Phototropins (phot1 and phot2) are autophosphorylating serine/threonine kinases that function as photoreceptors for phototropism, light-induced chloroplast movement, and stomatal opening in Arabidopsis . The N-terminal region of phot1 and phot2 contains two specialized PAS domains, designated LOV1 and LOV2, which function as binding sites for the chromophore flavin mononucleotide (FMN). Both LOV1 and LOV2 undergo a self-contained photocycle, which involves the formation of a covalent adduct between the FMN chromophore and a conserved active-site cysteine residue (Cys39). Replacement of Cys39 with alanine abolishes the light-induced photochemical reaction of LOV1 and LOV2. Here we have used the Cys39Ala mutation to investigate the role of LOV1 and LOV2 in regulating phototropin function. Photochemical analysis of a bacterially expressed LOV1 + LOV2 fusion protein indicates that LOV2 functions as the predominant light-sensing domain for phot1. LOV2 also plays a major role in mediating light-dependent autophosphorylation of full-length phot1 expressed in insect cells and transgenic Arabidopsis . Moreover, photochemically active LOV2 alone in full-length phot1 is sufficient to elicit hypocotyl phototropism in transgenic Arabidopsis , whereas photochemically active LOV1 alone is not. Further photochemical and biochemical analyses also indicate that the LOV1 and LOV2 domains of phot2 exhibit distinct roles. The significance for the different roles of the phototropin LOV domains is discussed. |
| Document Type: Article |
| Language: English |
| Reprint Address: Briggs, WR (reprint author), Carnegie Inst Washington, Dept Plant Biol, 290 Panama St, Stanford, CA 94305 USA |
Addresses:
1. Carnegie Inst Washington, Dept Plant Biol, Stanford, CA 94305 USA
2. Univ Calif Santa Cruz, Dept Chem & Biochem, Santa Cruz, CA 95064 USA |
| Publisher: BLACKWELL PUBLISHING LTD, 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND |
| Subject Category: Plant Sciences |
| IDS Number: 604FC |
| ISSN: 0960-7412 |
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