The de novo folate synthesis pathway is a well-established drug target in the treatment of many infectious diseases. Antimalarial antifolate drugs have proven to be effective against malaria, however, rapid drug resistance has emerged on the two primary targeted enzymes: dihydrofolate reductase and dihydroptoreate synthase. The need to identify alternative antifolate drugs and novel metabolic targets is of imminent importance. The 6-pyruvol tetrahydropterin synthase (PTPS) enzyme belongs to the tunneling fold protein superfamily which is characterized by a distinct central tunnel/cavity. The enzyme catalyzes the second reaction step of the parasite’s de novo folate synthesis pathway and is responsible for the conversion of 7,8-dihydroneopterin to 6-pyruvoyl-tetrahydropterin. In this study, we examine the structural dynamics of Plasmodium falciparum PTPS using the anisotropic network model, to elucidate the collective motions that drive the function of the enzyme and identify potential sites for allosteric modulation of its binding properties. Based on our modal analysis, we identified key sites in the N-terminal domains and central helices which control the accessibility to the active site. Notably, the N-terminal domains were shown to regulate the open-to-closed transition of the tunnel, via a distinctive wringing motion that deformed the core of the protein. We, further, combined the dynamic analysis with motif discovery which revealed highly conserved motifs that are unique to the Plasmodium species and are located in the N-terminal domains and central helices. This provides essential structural information for the efficient design of drugs such as allosteric modulators that would have high specificity and low toxicity as they do not target the PTPS active site that is highly conserved in humans.

的 从头叶酸合成途径是治疗许多传染病的公认药物靶标。抗疟疾抗叶酸药物已被证明对疟疾有效，但是，在两种主要的靶向酶上出现了快速耐药性：二氢叶酸还原酶和二氢戊酸合酶。鉴定替代抗叶酸药物和新的代谢靶标的需求迫在眉睫。6-丙酮酸四氢蝶呤合酶（PTPS）酶属于隧道折叠蛋白超家族，其特征是独特的中央隧道/空腔。该酶催化寄生虫的第二反应步骤从头叶酸合成途径，负责将7,8-二氢蝶呤转化为6-丙酮酰-四氢蝶呤。在这项研究中，我们研究了恶性疟原虫PTPS使用各向异性网络模型阐明了驱动酶功能的集体运动，并确定了变构调节其结合特性的潜在位点。根据我们的模态分析，我们确定了N末端域和中央螺旋中的关键位点，这些关键位点控制着对活性位点的可及性。值得注意的是，N末端结构域通过独特的拧紧运动使蛋白的核心变形，从而调节了通道的从开到关的过渡。我们进一步将动态分析与基序发现相结合，揭示了高度保守的基序，这些基序是疟原虫物种特有的，位于N末端结构域和中央螺旋中。