Department of Chemistry and Biochemistry, Montclair State University, Montclair, New Jersey, United States of America.
School of Pharmacy and Health Sciences, Fairleigh Dickinson University, Florham Park, New Jersey, United States of America.
PLoS Negl Trop Dis. 2023 Apr 27;17(4):e0011303. doi: 10.1371/journal.pntd.0011303. eCollection 2023 Apr.
Lymphatic filariasis is a debilitating illness with an estimated 50 million cases as of 2018. The majority of cases are caused by the parasitic worm W. bancrofti and additional cases by the worms B. malayi and B. timori. Dihydrofolate reductase (DHFR) is an established target in the treatment of cancer, bacterial, and protozoal infections and may be a potential target for drugs targeting parasitic worm infections, including filariasis. Recent studies have shown that known antifolate compounds, including methotrexate, inhibit the activity of W. bancrofti DHFR (WbDHFR). However, the absence of structural information for filarial DHFRs has limited the study of more in-depth structure-function relationships. We report the structure of WbDHFR complexed with NADPH and folate using X-ray diffraction data measured to 2.47 Å resolution. The structure of WbDHFR reveals the usual DHFR fold and is currently only the second nematode DHFR structure in the Protein Data Bank. The equilibrium dissociation constants for NADPH (90 ± 29 nM) and folate (23 ± 4 nM) were determined by equilibrium titrations. The interactions of known antifolates with WbDHFR were analyzed using molecular docking programs and molecular dynamics simulations. Antifolates with a hydrophobic core and extended linker formed favorable interactions with WbDHFR. These combined data should now facilitate the rational design of filarial DHFR inhibitors, which in turn can be used to determine whether DHFR is a viable drug target for filariasis and whether existing antifolates may be repurposed for its treatment.
淋巴丝虫病是一种使人虚弱的疾病，截至 2018 年，估计有 5000 万人患有该病。大多数病例是由寄生蠕虫 W. bancrofti 引起的，另有病例是由 B. malayi 和 B. timori 引起的。二氢叶酸还原酶 (DHFR) 是治疗癌症、细菌和原生动物感染的既定靶点，也可能是针对寄生虫感染（包括丝虫病）的药物的潜在靶点。最近的研究表明，已知的抗叶酸化合物，包括甲氨蝶呤，可抑制 W. bancrofti DHFR（WbDHFR）的活性。然而，由于缺乏丝状 DHFR 的结构信息，限制了对更深入的结构-功能关系的研究。我们报告了用 X 射线衍射数据测量到 2.47 Å 分辨率的 WbDHFR 与 NADPH 和叶酸复合物的结构。WbDHFR 的结构揭示了通常的 DHFR 折叠，目前仅在蛋白质数据库中是第二个线虫 DHFR 结构。通过平衡滴定确定 NADPH（90 ± 29 nM）和叶酸（23 ± 4 nM）的平衡解离常数。使用分子对接程序和分子动力学模拟分析了已知抗叶酸与 WbDHFR 的相互作用。具有疏水核心和扩展接头的抗叶酸与 WbDHFR 形成有利的相互作用。这些综合数据现在应该有助于合理设计丝虫 DHFR 抑制剂，这反过来又可以用来确定 DHFR 是否是丝虫病的可行药物靶点，以及现有的抗叶酸是否可以重新用于其治疗。
