1.4 ANGSTROM STRUCTURE OF PHOTOACTIVE YELLOW PROTEIN, A CYTOSOLIC PHOTORECEPTOR - UNUSUAL FOLD, ACTIVE-SITE, AND CHROMOPHORE
1.4 ANGSTROM STRUCTURE OF PHOTOACTIVE YELLOW PROTEIN, A CYTOSOLIC PHOTORECEPTOR - UNUSUAL FOLD, ACTIVE-SITE, AND CHROMOPHORE
复制标题
DOI：
10.1021/bi00019a004
复制
发表时间：
1995-05-16
期刊：
影响因子：
2.9
通讯作者：
GETZOFF, ED
中科院分区：
文献类型：
--
作者：
BORGSTAHL, GEO;WILLIAMS, DR;GETZOFF, ED
感光蛋白质将其发色团捕获的光能引导到一个光循环中。蛋白质的结构必须适应光周期，并促进导致信号转导的化学或构象变化。用多种同象取代法测定的光活性黄蛋白的1.4埃晶体结构，提供了具有光循环的蛋白质的原子分辨率的第一视图。与原始的链追踪不同，α/β折叠与信号转导蛋白profilin和SH2结构域的不同部分显示出惊人的相似之处。在光活性黄色蛋白的暗态结构中，新的4-羟基肉桂基发色团共价连接到Cys69上，埋藏在蛋白质的主要疏水核心中，并在两端通过氢键连接。在活性中心，发色团的黄色阴离子形式是通过从Tyr42和埋藏的Glu46的侧链到酚氧原子的氢键以及与Arg52的带正电荷的胍基的静电互补来稳定的。Thr50通过活性中心氢键网络进一步连接Tyr42、Glu46和Arg52。Arg52位于蛋白质表面的凹面上，毗邻负静电势的优势斑块，保护发色团免受溶剂的影响，并形成趋光信号的通道。总体而言，光活性黄色蛋白的高分辨率结构支持这样一种机制，即静电相互作用为光子诱导的重排和有效的蛋白质介导的信号转导创造了一个活跃的位置。
A photosensing protein directs light energy captured by its chromophore into a photocycle. The protein's structure must accommodate the photocycle and promote the resulting chemical or conformational changes that lead to signal transduction. The 1.4 Angstrom crystallographic structure of photoactive yellow protein, determined by multiple isomorphous replacement methods, provides the first view at atomic resolution of a protein with a photocycle. The alpha/beta fold, which differs from the original chain tracing, shows striking similarity to distinct parts of the signal transduction proteins profilin and the SH2 domain. In the dark state structure of photoactive yellow protein, the novel 4-hydroxycinnamyl chromophore, covalently attached to Cys69, is buried within the major hydrophobic core of the protein and is tethered at both ends by hydrogen bonds. In the active site, the yellow anionic form of the chromophore is stabilized by hydrogen bonds from the side chains of Tyr42 and buried Glu46 to the phenolic oxygen atom and by electrostatic complementarity with the positively charged guanidinium group of Arg52. Thr50 further interlocks Tyr42, Glu46, and Arg52 through a network of active site hydrogen bonds. Arg52, located in a concavity of the protein surface adjacent to the dominant patch of negative electrostatic potential, shields the chromophore from solvent and is positioned to form a gateway for the phototactic signal. Overall, the high-resolution structure of photoactive yellow protein supports a mechanism whereby electrostatic interactions create an active site poised for photon-induced rearrangements and efficient protein-mediated signal transduction.