In Vivo phosphorylation site mapping and functional characterization of Arabidopsis phototropin 1

Sullivan, S. , Thomson, C. E., Lamont, D. J., Jones, M. A. and Christie, J. M. (2008) In Vivo phosphorylation site mapping and functional characterization of Arabidopsis phototropin 1. Molecular Plant, 1(1), pp. 178-194. (doi: 10.1093/mp/ssm017) (PMID:20031924)

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Phototropins (phot1 and phot2) are blue-light receptor kinases controlling a range of responses that optimize the photosynthetic efficiency of plants. Light sensing is mediated by two flavin-binding motifs, known as LOV1 and LOV2, located within the N-terminal region of the protein. Photoexcitation via LOV2 leads to activation of the C-terminal kinase domain and consequently receptor autophosphorylation. However, knowledge of the in-vivo phosphorylation sites for Arabidopsis phototropins is lacking and has impeded progress in elucidating the functional significance of receptor phosphorylation. We have purified phot1 from Arabidopsis and identified the in-vivo sites of receptor phosphorylation by liquid chromatography tandem mass spectrometry. Arabidopsis-derived phot1 binds flavin mononucleotide as chromophore and is phosphorylated at four major sites located upstream of LOV2 (Ser58, Ser85, Ser350, and Ser410), three of which are induced by blue light. Nevertheless, structure-function analysis indicates that the biological activity of phot1 can be attributed to a modular unit comprising the LOV2-kinase region of the protein. Thus, peptide regions upstream of LOV2, including the sites of receptor phosphorylation identified here, do not appear to be important for receptor signaling. By contrast, these regions may be necessary for maximizing stomatal performance and possibly light-induced relocalization of phot1

Item Type:Articles
Glasgow Author(s) Enlighten ID:Jones, Dr Matt and Christie, Professor John and Sullivan, Dr Stuart
Authors: Sullivan, S., Thomson, C. E., Lamont, D. J., Jones, M. A., and Christie, J. M.
Subjects:Q Science > QH Natural history > QH301 Biology
Q Science > QK Botany
College/School:College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
Journal Name:Molecular Plant
Journal Abbr.:Mol. Plant
Publisher:Oxford University Press
ISSN (Online):1752-9867
Published Online:01 January 2007

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
378561Characterisation of the phot1-interacting protein AtMRD1 and its role in regulating phototropismJohn ChristieBiotechnology and Biological Sciences Research Council (BBSRC)BB/C000366/1Institute of Molecular Cell and Systems Biology