生物谷：在發(fā)表于《生物化學(xué)雜志》（Journal of Biological Chemistry）上的文章中,，來自Missouri-Columbia大學(xué)的科學(xué)家報(bào)道了他們?cè)谥参镖吂庑詸C(jī)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(zhǎng)的一種現(xiàn)象,。
趨光作用通過植物中的光感受器探測(cè)到有方向性的藍(lán)光而激發(fā),。MU的生物科學(xué)系教授MannieLiscum表示,，了解這一機(jī)制對(duì)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(jī)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(jī)制來優(yōu)化植物捕捉陽(yáng)光進(jìn)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(zhǎng)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(hào)的調(diào)節(jié)過程，擬南芥是一種常用于實(shí)驗(yàn)室研究的模式植物,。小組主要分析了一種對(duì)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(zhǎng)過程中的NPH3是一種被磷酸化的蛋白,。而當(dāng)它們暴露于陽(yáng)光下時(shí)，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(dǎo)致NPH3去除磷酸基，從而使得趨光信號(hào)能進(jìn)一步傳遞,。
Liscum說：“我們發(fā)現(xiàn)暴露于藍(lán)光下時(shí)NPH3將去磷酸化,，這一過程通過藍(lán)光激活phot1而實(shí)現(xiàn)。”Liscum和Pedmale目前計(jì)劃進(jìn)一步研究哪一個(gè)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.
