Collaborative Research: Investigations of the Plant Photoreceptor Kinase Family of Phototropins

植物光感受器介导了从生理到生化和分子水平的广泛的对光的反应，并且存在于从种子萌发到营养生长的几乎所有阶段到开花和衰老的整个植物发育过程中。目前已知的光感受器有光敏色素、隐色素和光感受器。促光蛋白是一种新的、以前未被表征的一类光感受器。这些双显色性光感受器结合两个FMN分子，与任何已知的光感受器不同，并通过独特的初始光化学作用并导致自磷酸化。目前的研究重点是嗜光蛋白（nph1）和迄今为止描述的各种nph1样蛋白。这些蛋白在异源系统中以发色团结合结构域和全长蛋白的形式表达。表达的蛋白，无论是天然结构体还是具有位点特异性突变的蛋白，都具有光活性。我们计划对各种分离的发色团结合结构域和全长蛋白进行有限的生化和详细的生物物理表征。生化研究将强调使用突变体结构来探测初始光化学。后者将重点研究探索光激活光化学的分子机制及其在蛋白质水平上的影响。这些研究将涉及时间分辨光学和振动光谱学。从古细菌到哺乳动物的多种蛋白质中，发色团结合结构域与所谓的PAS结构域密切相关，这应该为我们理解这些结构域的功能提供一个新的维度。

0090837BogomolniPlant photoreceptors mediate a broad spectrum of responses to light, ranging from the physiological through to the biochemical and molecular levels, and are present throughout plant development from seed germination through virtually all phases of vegetative growth to flowering and senescence. Currently well-known photoreceptors are phytochromes, cryptochromes, and phototropins. Phototropins represent a new and previously uncharacterized class of photoreceptors. These dual chromophoric photoreceptors, binding two molecules of FMN, are unlike any of the known classes of photoreceptors , and operate through an initial photochemistry that is unique and leads to autophosphorylation. The present project is focused on the chromoprotein phototropin (nph1) and the various nph1-like proteins described to date. These proteins are expressed in heterologous systems as the chromophore-binding domains and as the full length proteins. The expressed proteins both the native constructs and those with site-specific mutations are in the photoactive form. We plan to undertake a limited biochemical and detailed biophysical characterization of the various isolated chromophore-binding domains and of the full-length protein. The biochemical studies will emphasize the use of mutant constructs to probe the initial photochemistry. The latter will focus on studies probing the molecular mechanism by which light activates the photochemistry and its consequences at the protein level. These studies will involve time-resolved optical and vibrational spectroscopy. The chromophore-binding domains are closely related to domains (so-called PAS domains) in a diverse range of proteins from archaea through mammals, and should provide a new dimension to our understanding of the functions of these domains.