Li Qi, Huang Yue, Liu Xichun, Gan Jianhua, Chen Hao, Yang Cai-Guang
From the Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
the Coordination Chemistry Institute and State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China, and.
J Biol Chem. 2016 May 20;291(21):11083-93. doi: 10.1074/jbc.M115.711895. Epub 2016 Mar 25.
The AlkB repair enzymes, including Escherichia coli AlkB and two human homologues, ALKBH2 and ALKBH3, are iron(II)- and 2-oxoglutarate-dependent dioxygenases that efficiently repair N(1)-methyladenine and N(3)-methylcytosine methylated DNA damages. The development of small molecule inhibitors of these enzymes has seen less success. Here we have characterized a previously discovered natural product rhein and tested its ability to inhibit AlkB repair enzymes in vitro and to sensitize cells to methyl methane sulfonate that mainly produces N(1)-methyladenine and N(3)-methylcytosine lesions. Our investigation of the mechanism of rhein inhibition reveals that rhein binds to AlkB repair enzymes in vitro and promotes thermal stability in vivo In addition, we have determined a new structural complex of rhein bound to AlkB, which shows that rhein binds to a different part of the active site in AlkB than it binds to in fat mass and obesity-associated protein (FTO). With the support of these observations, we put forth the hypothesis that AlkB repair enzymes would be effective pharmacological targets for cancer treatment.
包括大肠杆菌AlkB以及两种人类同源物ALKBH2和ALKBH3在内的AlkB修复酶，是依赖于铁（II）和2-氧代戊二酸的双加氧酶，可有效修复N（1）-甲基腺嘌呤和N（3）-甲基胞嘧啶甲基化的DNA损伤。这些酶的小分子抑制剂的开发成效较小。在此，我们对一种先前发现的天然产物大黄酸进行了表征，并测试了其在体外抑制AlkB修复酶以及使细胞对主要产生N（1）-甲基腺嘌呤和N（3）-甲基胞嘧啶损伤的甲磺酸甲酯敏感的能力。我们对大黄酸抑制机制的研究表明，大黄酸在体外与AlkB修复酶结合，并在体内促进热稳定性。此外，我们确定了大黄酸与AlkB结合的新结构复合物，这表明大黄酸与AlkB活性位点结合的部位不同于其与脂肪量和肥胖相关蛋白（FTO）结合的部位。基于这些观察结果，我们提出假设，AlkB修复酶将成为癌症治疗的有效药理学靶点。
