Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan.
School of Biomedical Sciences, Chung Shan Medical University, No.110, Sec.1, Chien-Kuo N. Rd., Taichung City, Taiwan.
Biochem Biophys Res Commun. 2021 Apr 30;551:33-37. doi: 10.1016/j.bbrc.2021.03.001. Epub 2021 Mar 11.
Dihydroorotase (DHOase) is the third enzyme in the de novo biosynthesis pathway of pyrimidine nucleotides and considered an attractive target for potential antimalarial, anticancer, and antipathogen chemotherapy. Whether the FDA-approved clinical drug 5-fluorouracil (5-FU) that is used to target the enzyme thymidylate synthase for anticancer therapy can also bind to DHOase remains unknown. Here, we report the crystal structures of DHOase from Saccharomyces cerevisiae (ScDHOase) complexed with malate, 5-FU, and 5-aminouracil (5-AU). ScDHOase shares structural similarity with Escherichia coli DHOase. We also characterized the binding of 5-FU and 5-AU to ScDHOase by using the fluorescence quenching method. These complexed structures revealed that residues Arg18, Asn43, Thr106, and Ala275 of ScDHOase were involved in the 5-FU (PDB entry 6L0B) and 5-AU binding (PDB entry 6L0F). Overall, these results provide structural insights that may facilitate the development of new inhibitors targeting DHOase and constitute the 5-FU and 5-AU interactomes for further clinical chemotherapies.
二氢乳清酸酶（DHOase）是嘧啶核苷酸从头生物合成途径中的第三酶，被认为是抗疟、抗癌和抗病原体化疗的潜在靶点。美国食品和药物管理局（FDA）批准的临床药物 5-氟尿嘧啶（5-FU）用于针对酶胸苷酸合酶的抗癌治疗，它是否也能与 DHOase 结合尚不清楚。在这里，我们报告了酿酒酵母（ScDHOase）二氢乳清酸酶与苹果酸、5-FU 和 5-氨基尿嘧啶（5-AU）复合物的晶体结构。ScDHOase 与大肠杆菌 DHOase 具有结构相似性。我们还通过荧光猝灭法对 5-FU 和 5-AU 与 ScDHOase 的结合进行了表征。这些复合物结构表明，ScDHOase 的残基 Arg18、Asn43、Thr106 和 Ala275 参与了 5-FU（PDB 条目 6L0B）和 5-AU 结合（PDB 条目 6L0F）。总的来说，这些结果提供了结构上的见解，可能有助于开发针对 DHOase 的新抑制剂，并构成 5-FU 和 5-AU 的相互作用组，以进一步进行临床化疗。
