Department of Biochemistry, University of Bayreuth, 95447, Bayreuth, Germany.
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
Nat Commun. 2022 May 12;13(1):2618. doi: 10.1038/s41467-022-30252-4.
In nature as in biotechnology, light-oxygen-voltage photoreceptors perceive blue light to elicit spatiotemporally defined cellular responses. Photon absorption drives thioadduct formation between a conserved cysteine and the flavin chromophore. An equally conserved, proximal glutamine processes the resultant flavin protonation into downstream hydrogen-bond rearrangements. Here, we report that this glutamine, long deemed essential, is generally dispensable. In its absence, several light-oxygen-voltage receptors invariably retained productive, if often attenuated, signaling responses. Structures of a light-oxygen-voltage paradigm at around 1 Å resolution revealed highly similar light-induced conformational changes, irrespective of whether the glutamine is present. Naturally occurring, glutamine-deficient light-oxygen-voltage receptors likely serve as bona fide photoreceptors, as we showcase for a diguanylate cyclase. We propose that without the glutamine, water molecules transiently approach the chromophore and thus propagate flavin protonation downstream. Signaling without glutamine appears intrinsic to light-oxygen-voltage receptors, which pertains to biotechnological applications and suggests evolutionary descendance from redox-active flavoproteins.
在自然界和生物技术中，光-氧-电压光感受器感知蓝光以引发时空定义明确的细胞反应。光子吸收驱动保守半胱氨酸和黄素发色团之间的硫代加合物形成。同样保守的、近端的谷氨酰胺将所得黄素质子化转化为下游氢键重排。在这里，我们报告说，这种长期以来被认为是必需的谷氨酰胺通常是可有可无的。在其不存在的情况下，几种光-氧-电压受体始终保留了有生产力的信号反应，尽管通常是减弱的。在大约 1Å 分辨率的光-氧-电压范例的结构揭示了高度相似的光诱导构象变化，无论谷氨酰胺是否存在。天然存在的、缺乏谷氨酰胺的光-氧-电压受体可能作为真正的光感受器发挥作用，我们为二鸟苷酸环化酶展示了这一点。我们提出，没有谷氨酰胺，水分子会短暂地接近发色团，从而将黄素质子化向下游传递。没有谷氨酰胺的信号传递似乎是光-氧-电压受体的固有特性，这与生物技术应用有关，并表明其从氧化还原活性黄素蛋白进化而来。
