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Mutational Analysis of Phototropin 1 Provides Insights into the Mechanism Underlying LOV2 Signal Transmission

Jones, MA and Feeney, KA and Kelly, SM and Christie, JM (2007) 'Mutational Analysis of Phototropin 1 Provides Insights into the Mechanism Underlying LOV2 Signal Transmission.' Journal of Biological Chemistry, 282 (9). pp. 6405-6414. ISSN 0021-9258

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Abstract

Phototropins (phot1 and phot2) are blue light-activated serine/threonine protein kinases that elicit a variety of photoresponses in plants. Light sensing by the phototropins is mediated by two flavin mononucleotide (FMN)-binding domains, designated LOV1 and LOV2, located in the N-terminal region of the protein. Exposure to light results in the formation of a covalent adduct between the FMN chromophore and a conserved cysteine residue within the LOV domain. LOV2 photoexcitation is essential for phot1 function in Arabidopsis and is necessary to activate phot1 kinase activity through light-induced structural changes within a conserved ?-helix situated C-terminal to LOV2. Here we have used site-directed mutagenesis to identify further amino acid residues that are important for phot1 activation by light. Mutagenesis of bacterially expressed LOV2 and full-length phot1 expressed in insect cells indicates that perturbation of the conserved salt bridge on the surface of LOV2 does not play a role in receptor activation. However, mutation of a conserved glutamine residue (Gln575) within LOV2, reported previously to be required to propagate structural changes at the LOV2 surface, attenuates light-induced autophosphorylation of phot1 expressed in insect cells without compromising FMN binding. These findings, in combination with double mutant analyses, indicate that Gln575 plays an important role in coupling light-driven cysteinyl adduct formation from within LOV2 to structural changes at the LOV2 surface that lead to activation of the C-terminal kinase domain.

Item Type: Article
Uncontrolled Keywords: Cell Line; Animals; Arabidopsis; Cysteine; Flavin Mononucleotide; Glutamine; Flavoproteins; Arabidopsis Proteins; Transfection; Mutagenesis, Site-Directed; DNA Mutational Analysis; Biological Clocks; Light Signal Transduction; Cryptochromes
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 12 Jan 2013 11:46
Last Modified: 06 Jan 2022 13:30
URI: http://repository.essex.ac.uk/id/eprint/5085

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