生物谷：在發(fā)表于《生物化學雜志》（Journal of Biological Chemistry）上的文章中,，來自Missouri-Columbia大學的科學家報道了他們在植物趨光性機制的分子水平上的新發(fā)現(xiàn),，趨光性是植物向著或背離光線生長的一種現(xiàn)象,。
趨光作用通過植物中的光感受器探測到有方向性的藍光而激發(fā)。MU的生物科學系教授MannieLiscum表示,，了解這一機制對于提高農(nóng)作物的種植水平有著非常重要的意義,。
Liscum說：“通過了解趨光性的分子機制，我們就可以提高植物的單位面積數(shù)量,，并增加其耐旱性,。例如，可以通過這些機制來優(yōu)化植物捕捉陽光進行光合作用的能力,，這能使植物獲得更多能量,，從而帶來更好的生長等農(nóng)業(yè)有力因素。”
Liscum和博士生UllasPedmale研究了擬南芥中的趨光性信號的調(diào)節(jié)過程,，擬南芥是一種常用于實驗室研究的模式植物,。小組主要分析了一種對于趨光性非常關(guān)鍵的蛋白NPH3，他們研究了這一蛋白的磷酸化作用,。利用一系列分析方法,，小組發(fā)現(xiàn)幼苗在黑暗中生長過程中的NPH3是一種被磷酸化的蛋白。而當它們暴露于陽光下時,，NPH3變得去磷酸化,。
以上結(jié)果顯示,，控制趨光性的主要感受器phot1吸收光將導致NPH3去除磷酸基,，從而使得趨光信號能進一步傳遞。
Liscum說：“我們發(fā)現(xiàn)暴露于藍光下時NPH3將去磷酸化，這一過程通過藍光激活phot1而實現(xiàn),。”Liscum和Pedmale目前計劃進一步研究哪一個氨基酸決定了NPH3的這一可逆磷酸化過程以及NPH3在植物的其它過程中起到的作用,。（援引 教育部科技發(fā)展中心）
原文鏈接：http://www.physorg.com/news102871414.html
原始出處:
Originally published In Press as doi:10.1074/jbc.M702551200 on May 10, 2007
J. Biol. Chem., Vol. 282, Issue 27, 19992-20001, July 6, 2007
Regulation of Phototropic Signaling in Arabidopsis via Phosphorylation State Changes in the Phototropin 1-interacting Protein NPH3*
Ullas V. Pedmale and Emmanuel Liscum1
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.
