Raghu Ram E V S, Kumar Ambrish, Biswas Subir, Kumar Ashutosh, Chaubey Sushma, Siddiqi Mohammad Imran, Habib Saman
Division of Molecular and Structural Biology, Central Drug Research Institute, Post Box 173, Chattar Manzil, Mahatma Gandhi Marg, Lucknow 226001, India.
Mol Biochem Parasitol. 2007 Jul;154(1):30-9. doi: 10.1016/j.molbiopara.2007.04.001. Epub 2007 Apr 7.
The DNA replication machinery of the Plasmodium falciparum apicoplast is a validated drug target. Nuclear-encoded gyrase subunits are predicted to play a critical role in maintaining DNA topology during the D-loop/bi-directional ori replication process of the parasite. We show the presence of P. falciparum gyrase subunits in parasite lysates by using antibodies generated against recombinant gyrase A and B. The ATPase activity of PfGyrB was inhibited by novobiocin that also caused parasite death in culture. Reduction of apicoplast/nuclear DNA ratio in the presence of novobiocin indicated that the drug targets apicoplast DNA replication. Molecular modeling of gyrase A and B subunits revealed extensive fold conservation with the Escherichia coli counterparts as well as the presence of a long disordered loop adjacent to the ATPase domain of PfGyrB. Our results have implications for development of PfGyrB as a drug target against malaria.
恶性疟原虫顶质体的DNA复制机制是一个经过验证的药物靶点。预测核编码的gyrase亚基在寄生虫的D环/双向ori复制过程中维持DNA拓扑结构方面起着关键作用。我们通过使用针对重组gyrase A和B产生的抗体，在寄生虫裂解物中显示了恶性疟原虫gyrase亚基的存在。新生霉素抑制了PfGyrB的ATPase活性，该药物也导致培养中的寄生虫死亡。在新生霉素存在下，顶质体/核DNA比例降低，表明该药物靶向顶质体DNA复制。gyrase A和B亚基的分子建模显示，与大肠杆菌对应物相比，其折叠结构具有广泛的保守性，并且在PfGyrB的ATPase结构域附近存在一个长的无序环。我们的结果对将PfGyrB开发为抗疟疾药物靶点具有重要意义。
