Crystal structure of Mycobacterium tuberculosis catalase-peroxidase
Crystal structure of Mycobacterium tuberculosis catalase-peroxidase
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DOI：
10.1074/jbc.m402382200
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发表时间：
2004-09-10
影响因子：
4.8
通讯作者：
Brown, KA
中科院分区：
文献类型：
--
作者：
Bertrand, T;Eady, NAJ;Brown, KA
结核分枝杆菌过氧化氢酶-过氧化物酶是一种多功能血红素依赖酶，可激活核心抗结核药物异烟肼。已经进行了大量的研究来阐明异烟肼激活的酶依赖机制，并且有充分的证据表明，降低过氧化氢酶-过氧化物酶活性或使其失活的突变导致结核分枝杆菌异烟肼耐药性水平增加。由于缺乏该酶的三维结构，迄今为止对该酶的催化活性和突变对其作用的影响的解释受到限制。为了提供一个更准确的结核杆菌过氧化氢酶的三维结构模型，我们已经将酶结晶，现在报告其晶体结构细化到2.4埃的分辨率。该结构揭示了二聚体组装的新信息，并提供了可能在催化中起作用的残基的位置信息，包括蛋白质基自由基形成的候选物。模型和计算研究表明，异烟肼的结合位点位于三角洲-中位血红素边缘附近，而不是目前提出的表面环结构。结核分枝杆菌过氧化氢酶-过氧化物酶晶体结构的可用性也允许对引起临床分离株异烟肼耐药水平升高的突变的结构和功能影响进行更有信心的解释。
The Mycobacterium tuberculosis catalase-peroxidase is a multifunctional heme-dependent enzyme that activates the core anti-tuberculosis drug isoniazid. Numerous studies have been undertaken to elucidate the enzyme-dependent mechanism of isoniazid activation, and it is well documented that mutations that reduce activity or inactivate the catalase-peroxidase lead to increased levels of isoniazid resistance in M. tuberculosis. Interpretation of the catalytic activities and the effects of mutations upon the action of the enzyme to date have been limited due to the lack of a three-dimensional structure for this enzyme. In order to provide a more accurate model of the three-dimensional structure of the M. tuberculosis catalase-peroxidase, we have crystallized the enzyme and now report its crystal structure refined to 2.4-Angstrom resolution. The structure reveals new information about dimer assembly and provides information about the location of residues that may play a role in catalysis including candidates for protein-based radical formation. Modeling and computational studies suggest that the binding site for isoniazid is located near the delta-meso heme edge rather than in a surface loop structure as currently proposed. The availability of a crystal structure for the M. tuberculosis catalase-peroxidase also permits structural and functional effects of mutations implicated in causing elevated levels of isoniazid resistance in clinical isolates to be interpreted with improved confidence.