State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan, 430062, China.
Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
Angew Chem Int Ed Engl. 2018 Nov 12;57(46):15060-15064. doi: 10.1002/anie.201808231. Epub 2018 Oct 23.
Found recently in stignomatales, the Stig cyclases catalyze the Cope rearrangement and intramolecular cyclization to produce complex indole alkaloids. Five crystal structures were solved of subfamily 1 and 2 Stig cyclases, which adopt a β-sandwich fold like the non-catalytic carbohydrate-binding motif. Several complex structures were also determined of indole-based compounds, which are bound to the hydrophobic terminal cavity, where a conserved Asp residue makes an H-bond to the indole N and triggers the acid-catalyzed Cope rearrangement. Through analyzing the enzyme-ligand interactions and mutagenesis experiments, several aromatic residues were found important in catalysis. Apart from a common substrate binding mode and catalytic mechanism, potential subfamily variations that may attribute to the different product specificity are implicated. These results shall expand our scope of enzymology, in particular for further investigation of the biosynthetic Cope rearrangement.
最近在石蒜科中发现，Stig 环化酶催化 Cope 重排和分子内环化，生成复杂的吲哚生物碱。已经解决了亚家族 1 和 2 Stig 环化酶的五个晶体结构，它们采用类似于非催化碳水化合物结合基序的 β-三明治折叠。还确定了几种基于吲哚的化合物的复杂结构，这些化合物结合到疏水性末端腔中，其中保守的 Asp 残基与吲哚 N 形成氢键，并触发酸催化的 Cope 重排。通过分析酶-配体相互作用和突变实验，发现几个芳香族残基在催化中很重要。除了常见的底物结合模式和催化机制外，还暗示了可能导致不同产物特异性的潜在亚家族变化。这些结果将扩展我们对酶学的理解，特别是对生物合成 Cope 重排的进一步研究。
