Design of potential bisubstrate inhibitors against Mycobacterium tuberculosis (Mtb) 1-deoxy-d-xylulose 5-phosphate reductoisomerase (Dxr)—evidence of a novel binding mode
作者:Géraldine San Jose、Emily R. Jackson、Eugene Uh、Chinchu Johny、Amanda Haymond、Lindsay Lundberg、Chelsea Pinkham、Kylene Kehn-Hall、Helena I. Boshoff、Robin D. Couch、Cynthia S. Dowd
DOI:10.1039/c3md00085k
日期:——
In most bacteria, the nonmevalonate pathway is used to synthesize isoprene units. Dxr, the second step in the pathway, catalyzes the NADPH-dependent reductive isomerization of 1-deoxy-D-xylulose-5-phosphate (DXP) to 2-C-methyl-D-erythritol-4-phosphate (MEP). Dxr is inhibited by natural products fosmidomycin and FR900098, which bind in the DXP binding site. These compounds, while potent inhibitors of Dxr, lack whole cell activity against Mycobacterium tuberculosis (Mtb) due to their polarity. Our goal was to use the Mtb Dxr-fosmidomycin co-crystal structure to design bisubstrate ligands to bind to both the DXP and NADPH sites. Such compounds would be expected to demonstrate improved whole cell activity due to increased lipophilicity. Two series of compounds were designed and synthesized. Compounds from both series inhibited Mtb Dxr. The most potent compound (8) has an IC50 of 17.8 μM. Analysis shows 8 binds to Mtb Dxr via a novel, non-bisubstrate mechanism. Further, the diethyl ester of 8 inhibits Mtb growth making this class of compounds interesting lead molecules in the search for new antitubercular agents.
在大多数细菌中,非梅瓦隆酸途径用于合成异构烯单位。该途径的第二步是Dxr,它催化NADPH依赖的1-脱氧-D-木酮糖-5-磷酸(DXP)转化为2-C-甲基-D-赤藓糖-4-磷酸(MEP)的还原异构化反应。Dxr受到天然产品fosmidomycin和FR900098的抑制,这些化合物与DXP结合位点结合。这些化合物虽然是Dxr的强效抑制剂,但由于其极性,缺乏对结核分枝杆菌(Mtb)的全细胞活性。我们的目标是利用Mtb Dxr-fosmidomycin共晶结构设计双底物配体,以同时结合DXP和NADPH位点。这类化合物预计由于其增强的疏水性而表现出更好的全细胞活性。设计并合成了两系列化合物。两系列中的化合物均抑制Mtb Dxr。最强效的化合物(8)的IC50为17.8 µM。分析表明,化合物8通过一种新颖的非双底物机制与Mtb Dxr结合。此外,化合物8的二乙酯抑制了Mtb的生长,这使得这一类化合物成为寻找新抗结核药物的有趣领先分子。