Tizón Lorena, Maneiro María, Peón Antonio, Otero José M, Lence Emilio, Poza Sergio, van Raaij Mark J, Thompson Paul, Hawkins Alastair R, González-Bello Concepción
Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela, calle Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain.
Org Biomol Chem. 2015 Jan 21;13(3):706-16. doi: 10.1039/c4ob01782j.
The irreversible inhibition of type I dehydroquinase (DHQ1), the third enzyme of the shikimic acid pathway, is investigated by structural, biochemical and computational studies. Two epoxides, which are mimetics of the natural substrate, were designed as irreversible inhibitors of the DHQ1 enzyme and to study the binding requirements of the linkage to the enzyme. The epoxide with the S configuration caused the covalent modification of the protein whereas no reaction was obtained with its epimer. The first crystal structure of DHQ1 from Salmonella typhi covalently modified by the S epoxide, which is reported at 1.4 Å, revealed that the modified ligand is surprisingly covalently attached to the essential Lys170 by the formation of a stable Schiff base. The experimental and molecular dynamics simulation studies reported here highlight the huge importance of the conformation of the C3 carbon of the ligand for covalent linkage to this type of aldolase I enzyme, revealed the key role played by the essential His143 as a Lewis acid in this process and show the need for a neatly closed active site for catalysis.
通过结构、生化和计算研究，对莽草酸途径的第三种酶——I型脱氢奎尼酸酶（DHQ1）的不可逆抑制作用进行了研究。设计了两种作为天然底物模拟物的环氧化物，作为DHQ1酶的不可逆抑制剂，并研究与该酶连接的结合要求。具有S构型的环氧化物导致蛋白质的共价修饰，而其差向异构体则未发生反应。报道了伤寒沙门氏菌DHQ1与S环氧化物共价修饰后的首个晶体结构，分辨率为1.4 Å，结果显示修饰后的配体通过形成稳定的席夫碱，惊人地与必需的赖氨酸170共价连接。本文报道的实验和分子动力学模拟研究突出了配体C3碳的构象对于与这类醛缩酶I酶共价连接的巨大重要性，揭示了必需的组氨酸143作为路易斯酸在此过程中所起的关键作用，并表明催化需要一个紧密封闭的活性位点。
