Professur für Organische Chemie (Lebensmittelchemie), Fakultät für Biologie, Chemie und Geowissenschaften, Universität Bayreuth, Universitätsstrasse 30, 95447, Bayreuth, Germany.
Zentrum für Biomolekulare Wirkstoffe, Leibniz Universität Hannover, Schneiderberg 38, 30167, Hannover, Germany.
Angew Chem Int Ed Engl. 2016 Oct 17;55(43):13589-13592. doi: 10.1002/anie.201607827. Epub 2016 Sep 27.
The olefin shift is an important modification during polyketide biosynthesis. Particularly for type I cis-AT PKS, little information has been gained on the enzymatic mechanisms involved. We present our in vitro investigations on the olefin shift occurring during ambruticin biosynthesis. The unique, multifunctional domain AmbDH4 catalyzes consecutive dehydration, epimerization, and enoyl isomerization. The resulting 3-enethioate is removed from the equilibrium by α-methylation catalyzed by the highly specific C-methyltransferase AmbM. This thermodynamically unfavorable overall process is enabled by the high, concerted substrate specificity of the involved enzymes. AmbDH4 shows close relationship to DH domains and initial mechanistic studies suggest that the olefin shift occurs via a similar proton-shuttling mechanism as previously described for EI domains from trans-AT-PKS.
烯烃移位是聚酮化合物生物合成过程中的一个重要修饰。特别是对于 I 型顺式-AT PKS，关于涉及的酶促机制几乎没有信息。我们介绍了在安布霉素生物合成过程中发生的烯烃移位的体外研究。独特的多功能域 AmbDH4 催化连续的脱水、差向异构化和烯酰异构化。由高度特异性的 C-甲基转移酶 AmbM 催化的α-甲基化将生成的 3-硫代乙酯从平衡中去除。这种热力学上不利的整体过程是由参与酶的高协同底物特异性所实现的。AmbDH4 与 DH 结构域密切相关，初步的机制研究表明，烯烃移位通过类似于先前描述的来自反式-AT-PKS 的 EI 结构域的类似质子转移机制发生。
