HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 27, 19992-20001, July 6, 2007

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 282/27/19992    most recent M702551200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pedmale, U. V. Articles by Liscum, E. Search for Related Content PubMed PubMed Citation Articles by Pedmale, U. V. Articles by Liscum, E. Social Bookmarking                      What's this?

Regulation of Phototropic Signaling in Arabidopsis via Phosphorylation State Changes in the Phototropin 1-interacting Protein NPH3^*

From the Division of Biological Sciences and the Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211

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.

Received for publication, March 26, 2007 , and in revised form, May 3, 2007.

^* This work was supported by National Science Foundation Grants IOS-0114992 and IOS-0415970 (to E. L.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Fig. S1.

¹ To whom correspondence should be addressed. Tel.: 573-882-2672; Fax: 573-882-0123; E-mail: liscume{at}missouri.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				J. J. Holland, D. Roberts, and E. Liscum Understanding phototropism: from Darwin to today J. Exp. Bot., May 1, 2009; 60(7): 1969 - 1978. [Abstract] [Full Text] [PDF]

				Y. Cheng, G. Qin, X. Dai, and Y. Zhao NPY genes and AGC kinases define two key steps in auxin-mediated organogenesis in Arabidopsis PNAS, December 30, 2008; 105(52): 21017 - 21022. [Abstract] [Full Text] [PDF]

				X. Chen, W.-H. Lin, Y. Wang, S. Luan, and H.-W. Xue An Inositol Polyphosphate 5-Phosphatase Functions in PHOTOTROPIN1 Signaling in Arabidopis by Altering Cytosolic Ca2+ PLANT CELL, February 1, 2008; 20(2): 353 - 366. [Abstract] [Full Text] [PDF]

				Y. Cheng, G. Qin, X. Dai, and Y. Zhao NPY1, a BTB-NPH3-like protein, plays a critical role in auxin-regulated organogenesis in Arabidopsis PNAS, November 20, 2007; 104(47): 18825 - 18829. [Abstract] [Full Text] [PDF]