Isoniazid Inhibits the Heme-Based Reactivity of Mycobacterium tuberculosis Truncated Hemoglobin N
Isoniazid Inhibits the Heme-Based Reactivity of Mycobacterium tuberculosis Truncated Hemoglobin N
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DOI：
10.1371/journal.pone.0069762
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发表时间：
2013-08-01
期刊：
影响因子：
3.7
通讯作者：
Coletta, Massimo
中科院分区：
文献类型：
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作者：
Ascenzi, Paolo;Coletta, Andrea;Coletta, Massimo
异烟肼是预防和治疗结核病的一线抗结核药物。该前药被称为KatG的分枝杆菌过氧化氢酶-过氧化物酶激活，从而抑制分枝杆菌细胞壁所需的分枝菌酸的合成。此外，通过KatG活化异烟肼产生一些自由基物质（例如，一氧化氮），其显示抗分枝杆菌活性。值得注意的是，分枝杆菌在活性氮和氧物质存在下在体内持续存在的能力意味着这些细菌中存在（假）酶促解毒系统，包括截短的血红蛋白（trHbs）。在这里，我们报告说，异烟肼可逆地结合铁和亚铁M。结核trHb N型（或I组;分别为Mt-trHbN（III）和Mt-trHbN（II））具有简单的双分子过程，其干扰基于血红素的光谱性质。异烟肼与Mt-trHbN（III）和Mt-trHbN（II）结合的热力学和动力学参数值为K =（1.1 +/- 0.1）x 10（24）M，k（开）=（5.3 +/- 0.6）x 10（3）M-1 s（-1）和k（关闭）=（4.6 +/- 0.5）x 10（-1）s（-1）;在pH 7.0和20.0 ℃时，D =（1.2 +/- 0.2）× 10（23）M，d（on）=（1.3 +/- 0.4）× 10（3）M-1 s（-1），d（off）= 1.5 +/- 0.4 s（-1）。因此，异烟肼竞争性抑制叠氮化物与Mt-trHbN（III）的结合和Mt-trHbN（III）催化的过氧亚硝酸盐异构化。此外，异烟肼抑制Mt-trHbN（II）氧化和羰基化。虽然Mt-trHbN-异烟肼复合物的结构是不可用的，在这里，我们通过对接模拟表明，异烟肼结合血红素-Fe原子确实可能发生。这些数据表明，异烟肼对损害分枝杆菌的基本功能（如清除活性氮和氧以及代谢）具有直接作用。
Isoniazid represents a first-line anti-tuberculosis medication in prevention and treatment. This prodrug is activated by a mycobacterial catalase-peroxidase enzyme called KatG in Mycobacterium tuberculosis), thereby inhibiting the synthesis of mycolic acid, required for the mycobacterial cell wall. Moreover, isoniazid activation by KatG produces some radical species (e.g., nitrogen monoxide), that display anti-mycobacterial activity. Remarkably, the ability of mycobacteria to persist in vivo in the presence of reactive nitrogen and oxygen species implies the presence in these bacteria of (pseudo-)enzymatic detoxification systems, including truncated hemoglobins (trHbs). Here, we report that isoniazid binds reversibly to ferric and ferrous M. tuberculosis trHb type N (or group I; Mt-trHbN(III) and Mt-trHbN(II), respectively) with a simple bimolecular process, which perturbs the heme-based spectroscopic properties. Values of thermodynamic and kinetic parameters for isoniazid binding to Mt-trHbN(III) and Mt-trHbN(II) are K = (1.1 +/- 0.1) x 10(24) M, k(on) = (5.3 +/- 0.6) x 10(3) M-1 s(-1) and k(off) = (4.6 +/- 0.5) x 10(-1) s(-1); and D = (1.2 +/- 0.2) x 10(23) M, d(on) = (1.3 +/- 0.4) x 10(3) M-1 s(-1), and d(off) = 1.5 +/- 0.4 s(-1), respectively, at pH 7.0 and 20.0 degrees C. Accordingly, isoniazid inhibits competitively azide binding to Mt-trHbN(III) and Mt-trHbN(III)-catalyzed peroxynitrite isomerization. Moreover, isoniazid inhibits Mt-trHbN(II) oxygenation and carbonylation. Although the structure of the Mt-trHbN-isoniazid complex is not available, here we show by docking simulation that isoniazid binding to the heme-Fe atom indeed may take place. These data suggest a direct role of isoniazid to impair fundamental functions of mycobacteria, e.g. scavenging of reactive nitrogen and oxygen species, and metabolism.