Regulation of phototropic signaling in Arabidopsis via phosphorylation state changes in the phototropin 1-interacting protein NPH3

Pedmale, U. V., Liscum, E. (July 2007) Regulation of phototropic signaling in Arabidopsis via phosphorylation state changes in the phototropin 1-interacting protein NPH3. J Biol Chem, 282 (27). pp. 19992-20001. ISSN 0021-9258 (Print)0021-9258

URL: http://www.ncbi.nlm.nih.gov/pubmed/17493935
DOI: 10.1074/jbc.M702551200

Abstract

Phototropism, or the directional growth (curvature) of various organs toward or away from incident light, represents a ubiquitous adaptive response within the plant kingdom. This response is initiated through the sensing of directional blue light (BL) by a small family of photoreceptors known as the phototropins. Of the two phototropins present in the model plant Arabidopsis thaliana, phot1 (phototropin 1) is the dominant receptor controlling phototropism. Absorption of BL by the sensory portion of phot1 leads, as in other plant phototropins, to activation of a C-terminal serine/threonine protein kinase domain, which is tightly coupled with phototropic responsiveness. Of the five phot1-interacting proteins identified to date, only one, NPH3 (non-phototropic hypocotyl 3), is essential for all phot1-dependent phototropic responses, yet little is known about how phot1 signals through NPH3. Here, we show that, in dark-grown seedlings, NPH3 exists as a phosphorylated protein and that BL stimulates its dephosphorylation. phot1 is necessary for this response and appears to regulate the activity of a type 1 protein phosphatase that catalyzes the reaction. The abrogation of both BL-dependent dephosphorylation of NPH3 and development of phototropic curvatures by protein phosphatase inhibitors further suggests that this post-translational modification represents a crucial event in phot1-dependent phototropism. Given that NPH3 may represent a core component of a CUL3-based ubiquitin-protein ligase (E3), we hypothesize that the phosphorylation state of NPH3 determines the functional status of such an E3 and that differential regulation of this E3 is required for normal phototropic responsiveness.

Item Type: Paper
Uncontrolled Keywords: Arabidopsis/growth & development/*metabolism Arabidopsis Proteins/*metabolism Carrier Proteins/metabolism Cryptochromes Enzyme Inhibitors/pharmacology Flavoproteins/metabolism Phosphoprotein Phosphatases/antagonists & inhibitors/metabolism Phototropism/drug effects/*physiology Protein Processing, Post-Translational/drug effects/*physiology *Seedlings Signal Transduction/drug effects/*physiology Ubiquitin-Protein Ligases/metabolism
Subjects: organism description > plant > Arabidopsis
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > plant proteins > cryptochromes
organism description > plant
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > protein phosphatase
organs, tissues, organelles, cell types and functions > tissues types and functions > signal transduction
CSHL Authors:
Communities: CSHL labs > Pedmale lab
Depositing User: Matt Covey
Date: 6 July 2007
Date Deposited: 13 Jun 2016 16:12
Last Modified: 13 Jun 2016 16:12
Related URLs:
URI: http://repository.cshl.edu/id/eprint/32864

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