Gerum A'Lissa B, Ulmer Jonathan E, Jacobus David P, Jensen Norman P, Sherman David R, Sibley Carol Hopkins
Department of Genome Sciences, University of Washington, Seattle, Washington 98195-7730, USA.
Antimicrob Agents Chemother. 2002 Nov;46(11):3362-9. doi: 10.1128/AAC.46.11.3362-3369.2002.
The ongoing selection of multidrug-resistant strains of Mycobacterium tuberculosis has markedly reduced the effectiveness of the standard treatment regimens. Thus, there is an urgent need for new drugs that are potent inhibitors of M. tuberculosis, that exhibit favorable resistance profiles, and that are well tolerated by patients. One promising drug target for treatment of mycobacterial infections is dihydrofolate reductase (DHFR; EC 1.5.1.3), a key enzyme in folate utilization. DHFR is an important drug target in many pathogens, but it has not been exploited in the search for drugs effective against M. tuberculosis. The triazine DHFR inhibitor WR99210 has been shown to be effective against other mycobacteria. We show here that WR99210 is also a potent inhibitor of M. tuberculosis and Mycobacterium bovis BCG growth in vitro and that resistance to WR99210 occurred less frequently than resistance to either rifampin or isoniazid. Screening of drugs with M. tuberculosis cultures is slow and requires biosafety level 3 facilities and procedures. We have developed an alternative strategy: initial screening in an engineered strain of the budding yeast Saccharomyces cerevisiae that is dependent on the M. tuberculosis DHFR for its growth. Using this system, we have screened 19 compounds related to WR99210 and found that 7 of these related compounds are also potent inhibitors of the M. tuberculosis DHFR. These studies suggest that compounds of this class are excellent potential leads for further development of drugs effective against M. tuberculosis.
不断出现的耐多药结核分枝杆菌菌株显著降低了标准治疗方案的有效性。因此，迫切需要新的药物，这些药物是结核分枝杆菌的有效抑制剂，具有良好的耐药性特征，并且患者耐受性良好。治疗分枝杆菌感染的一个有前景的药物靶点是二氢叶酸还原酶（DHFR；EC 1.5.1.3），它是叶酸利用中的关键酶。DHFR是许多病原体中的重要药物靶点，但在寻找有效对抗结核分枝杆菌的药物时尚未被利用。三嗪类DHFR抑制剂WR99210已被证明对其他分枝杆菌有效。我们在此表明，WR99210在体外也是结核分枝杆菌和牛分枝杆菌卡介苗生长的有效抑制剂，并且对WR99210产生耐药性的频率低于对利福平或异烟肼产生耐药性的频率。用结核分枝杆菌培养物进行药物筛选速度缓慢，需要生物安全3级设施和程序。我们开发了一种替代策略：在一种工程改造的酿酒酵母菌株中进行初步筛选，该菌株依赖结核分枝杆菌DHFR生长。利用这个系统，我们筛选了19种与WR99210相关的化合物，发现其中7种相关化合物也是结核分枝杆菌DHFR的有效抑制剂。这些研究表明，这类化合物是进一步开发有效对抗结核分枝杆菌药物的极佳潜在先导物。
