Catalytic role of carbonyl oxygens and water in selinadiene synthase
Catalytic role of carbonyl oxygens and water in selinadiene synthase
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羰基氧和水在硒二烯合酶中的催化作用
DOI：
10.1038/s41929-022-00735-0
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发表时间：
2022-02-17
期刊：
影响因子：
37.8
通讯作者：
Dickschat, Jeroen S.
中科院分区：
文献类型：
--
作者：
Wang, Yong-Heng;Xu, Houchao;Dickschat, Jeroen S.
萜烯脱氢酶（TS）催化自然界中最复杂的环化级联反应，产生和驯服活性碳阳离子。尽管去质子化-再质子化序列经常与TS催化相关，但对酶在这些过程中的作用知之甚少。本文通过量子力学（密度泛函理论）/分子力学分子动力学模拟，证明了Selina-4（15），7（11）-diene synthase（SdS）Gly 182的主链羰基氧具有碱和酸的双重作用，并与一个水分子同步作用。同位素标记实验证实了预测的立体化学过程与去质子化reprotonation序列的计算模型的支持。Gly 182位于SdS的G1/2螺旋断裂内，所有骨架羰基氧指向活性位点，具有识别底物构象、稳定碳阳离子中间体和锚定它们的位姿的功能。严格保守的G1/2螺旋断裂的I型TS从细菌，真菌和植物表明，它的功能，如这里所描述的TS催化可能是普遍的重要性。
Terpene synthases (TSs) catalyse the most complex cyclization cascades in nature, with generation and taming of reactive carbocations. Although deprotonation-reprotonation sequences are frequently relevant for TS catalysis, little is known how the enzyme acts in these processes. Here we show, through quantum mechanics (density functional theory)/molecular mechanics molecular dynamics simulations that the main-chain carbonyl oxygen of Gly182 of selina-4(15),7(11)-diene synthase (SdS) has a dual role as a base and an acid and acts in synchrony with one water molecule. The computational model is supported by isotopic labelling experiments confirming the predicted stereochemical course associated with the deprotonation-reprotonation sequence. Gly182 is located within the G1/2 helix break of SdS, with all backbone carbonyl oxygens pointing into the active site having functions in recognizing substrate conformation, stabilizing carbocation intermediates and anchoring their poses. The strict conservation of the G1/2 helix break in type I TSs from bacteria, fungi and plants suggests that its functions as described here may be of general importance in TS catalysis.