在绝大多数细菌中,原生动物和植物,甲基赤藓糖醇磷酸(MEP)途径用于合成异戊烯基二磷酸(IDP)和二甲基烯丙基二磷酸(DMADP),它们是类异戊二烯的前体。类异戊二烯,如胆固醇和辅酶Q,在生理活动中发挥各种关键作用,包括细胞膜的形成,蛋白质降解,细胞凋亡,和转录调控。相比之下,人类使用甲羟戊酸(MVA)途径生产IDP和DMADP,MEP途径中的蛋白质对抗菌剂具有吸引力。该途径由七个连续的酶促反应组成,其中4-二磷酸-2C-甲基-D-赤藓糖醇合成酶(IspD)和2C-甲基-D-赤藓糖醇2,4-环二磷酸合成酶(IspF)催化第三和第五步,分别。在这项研究中,我们表征了幽门螺杆菌IspDF和鲍曼不动杆菌IspD的酶活性和蛋白质结构。然后,使用基于直接相互作用的热转移测定,我们对已批准的药物库进行了化合物筛选,鉴定出27种可能与AbIspD结合的化合物.其中,两种天然产物,迷迭香酸和丹参酮IIA磺酸钠,对HpIspDF和AbIspD表现出抑制活性,通过与其中一种基质竞争,MEP。此外,丹参酮IIA磺酸钠也证明了对幽门螺杆菌的某些抗菌作用。总之,我们从批准的成分中鉴定出两种IspD抑制剂,拓宽了针对MEP途径的抗生素发现范围。
In a vast majority of bacteria, protozoa and plants, the methylerythritol phosphate (MEP) pathway is utilized for the synthesis of isopentenyl diphosphate (IDP) and dimethylallyl diphosphate (DMADP), which are precursors for isoprenoids. Isoprenoids, such as cholesterol and coenzyme Q, play a variety of crucial roles in physiological activities, including cell-membrane formation, protein degradation, cell apoptosis, and transcription regulation. In contrast, humans employ the mevalonate (MVA) pathway for the production of IDP and DMADP, rendering proteins in the MEP pathway appealing targets for antimicrobial agents. This pathway consists of seven consecutive enzymatic reactions, of which 4-diphosphocytidyl-2C-methyl-D-erythritol synthase (IspD) and 2C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF) catalyze the third and fifth steps, respectively. In this study, we characterized the enzymatic activities and protein structures of Helicobacter pylori IspDF and Acinetobacter baumannii IspD. Then, using the direct interaction-based thermal shift assay, we conducted a compound screening of an approved drug library and identified 27 hit compounds potentially binding to AbIspD. Among them, two natural products, rosmarinic acid and tanshinone IIA sodium sulfonate, exhibited inhibitory activities against HpIspDF and AbIspD, by competing with one of the substrates, MEP. Moreover, tanshinone IIA sodium sulfonate also demonstrated certain antibacterial effects against H. pylori. In summary, we identified two IspD inhibitors from approved ingredients, broadening the scope for antibiotic discovery targeting the MEP pathway.