Allosteric Communication of the Dimerization and the Catalytic Domain in Photoreceptor Guanylate Cyclase.

IF 2.9 3区 生物学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY
Biochemistry Biochemistry Pub Date : 2024-09-03 Epub Date: 2024-08-23 DOI:10.1021/acs.biochem.4c00170
Manisha Kumari Shahu, Fabian Schuhmann, Siu Ying Wong, Ilia A Solov'yov, Karl-Wilhelm Koch
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引用次数: 0

Abstract

Phototransduction in vertebrate photoreceptor cells is controlled by Ca2+-dependent feedback loops involving the membrane-bound guanylate cyclase GC-E that synthesizes the second messenger guanosine-3',5'-cyclic monophosphate. Intracellular Ca2+-sensor proteins named guanylate cyclase-activating proteins (GCAPs) regulate the activity of GC-E by switching from a Ca2+-bound inhibiting state to a Ca2+-free/Mg2+-bound activating state. The gene GUCY2D encodes for human GC-E, and mutations in GUCY2D are often associated with an imbalance of Ca2+ and cGMP homeostasis causing retinal disorders. Here, we investigate the Ca2+-dependent inhibition of the constitutively active GC-E mutant V902L. The inhibition is not mediated by GCAP variants but by Ca2+ replacing Mg2+ in the catalytic center. Distant from the cyclase catalytic domain is an α-helical domain containing a highly conserved helix-turn-helix motif. Mutating the critical amino acid position 804 from leucine to proline left the principal activation mechanism intact but resulted in a lower level of catalytic efficiency. Our experimental analysis of amino acid positions in two distant GC-E domains implied an allosteric communication pathway connecting the α-helical and the cyclase catalytic domains. A computational connectivity analysis unveiled critical differences between wildtype GC-E and the mutant V902L in the allosteric network of critical amino acid positions.

Abstract Image

感光器鸟苷酸环化酶二聚体和催化域的异构通讯
脊椎动物感光细胞中的光传导受 Ca2+ 依赖性反馈回路控制,其中涉及膜结合鸟苷酸环化酶 GC-E,它能合成第二信使鸟苷-3',5'-环状单磷酸。名为鸟苷酸环化酶激活蛋白(GCAPs)的细胞内 Ca2+ 传感蛋白通过从 Ca2+ 结合的抑制状态转换到无 Ca2+ /Mg2+ 结合的激活状态来调节 GC-E 的活性。GUCY2D 基因编码人类 GC-E,GUCY2D 基因突变通常与 Ca2+ 和 cGMP 平衡失调有关,会导致视网膜疾病。在这里,我们研究了组成型活性 GC-E 突变体 V902L 的 Ca2+ 依赖性抑制作用。这种抑制作用不是由 GCAP 变体介导的,而是由催化中心的 Ca2+ 取代 Mg2+ 介导的。与环化酶催化结构域相隔较远的是一个 α 螺旋结构域,该结构域包含一个高度保守的螺旋-转螺旋基团。将关键氨基酸位置 804 从亮氨酸突变为脯氨酸后,主要的激活机制保持不变,但催化效率却降低了。我们对两个相距较远的 GC-E 结构域的氨基酸位置进行了实验分析,这意味着存在一条连接 α 螺旋结构域和环化酶催化结构域的异位沟通途径。计算连接性分析揭示了野生型 GC-E 与突变体 V902L 在关键氨基酸位置的异构网络中的关键差异。
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来源期刊
Biochemistry Biochemistry
Biochemistry Biochemistry 生物-生化与分子生物学
CiteScore
5.50
自引率
3.40%
发文量
336
审稿时长
1-2 weeks
期刊介绍: Biochemistry provides an international forum for publishing exceptional, rigorous, high-impact research across all of biological chemistry. This broad scope includes studies on the chemical, physical, mechanistic, and/or structural basis of biological or cell function, and encompasses the fields of chemical biology, synthetic biology, disease biology, cell biology, nucleic acid biology, neuroscience, structural biology, and biophysics. In addition to traditional Research Articles, Biochemistry also publishes Communications, Viewpoints, and Perspectives, as well as From the Bench articles that report new methods of particular interest to the biological chemistry community.
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