In Vivo Phosphorylation Site Mapping and Functional Characterization of Arabidopsis Phototropin 1

作     者：Stuart Sullivan Catriona E. Thomson Douglas J. Lamont Matthew A. Jones John M. Christie 

作者机构：Plant Science Group Division of Biochemistry and Molecular Biology. Institute of Biomedical and Life Sciences University of Glasgow. University Avenue. Glasgow Scotland UK FingerPrints Proteomics Facility Post-Genomics and Molecular Interactions Centre. School of Life Sciences MSI/WTB/CIR Complex University of Dundee. Dundee Scotland UK 

出 版 物：《Molecular Plant》 (分子植物（英文版）)

年 卷 期：2008年第1卷第1期

页      面：178-194页

核心收录：

学科分类：0710[理学-生物学] 09[农学] 0903[农学-农业资源与环境] 0901[农学-作物学] 090302[农学-植物营养学] 0902[农学-园艺学] 

基　　金：Biotechnology and Biological Sciences Research Council,BBSRC: BB/C000366/1 Royal Society Gatsby Charitable Foundation 

主　　题：Phototropins (phot1 and phot2) lavin-binding motifs 

摘      要：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 LOVl 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 phos- phorylation. We have purified photl from Arabidopsis and identified the in-vivo sites of receptor phosphorylation by liquid chromatography tandem mass spectrometry. Arabidopsis-derived photl binds flavin mononucleotide as chromophore and is phosphorylated at four major sites located upstream of LOV2 （Ser^58, Ser^85, Ser^350, and Ser^410）, three of which are induced by blue light. Nevertheless, structure-function analysis indicates that the biological activity of photl 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 photl.