Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research, Ghaziabad, India.
DNA Repair (Amst). 2021 May;101:103078. doi: 10.1016/j.dnarep.2021.103078. Epub 2021 Feb 27.
Mitochondrion is an essential organelle in malaria parasite and its DNA must be maintained for optimal function during its complex life cycle. Base excision repair is one of the major pathways by which this is achieved. Apurinic/apyrimidinic (AP) endonucleases are important components of this pathway as they create a nick at the 5'-phosphodiester bond in the AP site and generate free 5'-phosphate and 3'-hydroxyl groups. Two class II AP endonucleases (Apn1 and Ape1) have been annotated in the Plasmodium berghei genome. Using reverse genetic approaches, we provide direct evidence that Apn1 is exclusively localized to the mitochondria of P. berghei. Surprisingly, our gene deletion study revealed a completely dispensable role of Apn1 for the entirety of the P. berghei life cycle. Apn1 parasites were found to successfully grow in the blood. They were transmitted normally to the mosquito midguts and salivary glands. Sporozoites obtained from the salivary glands were infective and achieved similar patency as WT. Our results help emphasize the non-availability of this enzyme as a plausible drug target. We also emphasize the importance of genetic validation of antimalarial drug targets before furthering them down the drug discovery pipeline.
线粒体是疟原虫的必需细胞器，其 DNA 必须在其复杂的生命周期中保持最佳功能。碱基切除修复是实现这一目标的主要途径之一。脱嘌呤/脱嘧啶 (AP) 内切酶是该途径的重要组成部分，因为它们在 AP 位点的 5'-磷酸二酯键处产生一个缺口，并生成游离的 5'-磷酸和 3'-羟基基团。在疟原虫伯氏疟原虫基因组中注释了两种 II 类 AP 内切酶 (Apn1 和 Ape1)。通过反向遗传方法，我们提供了直接证据表明 Apn1 仅定位于疟原虫的线粒体中。令人惊讶的是，我们的基因缺失研究表明 Apn1 在疟原虫生命周期的全部过程中完全可有可无。Apn1 寄生虫在血液中成功生长。它们正常传播到蚊子的中肠和唾液腺。从中肠获得的孢子能够感染并获得与 WT 相似的通透性。我们的研究结果有助于强调该酶作为合理药物靶点的不可用性。我们还强调在将抗疟药物靶点进一步推向药物发现管道之前，对其进行遗传验证的重要性。
