Characterization of the putative tryptophan synthase β-subunit from Mycobacterium tuberculosis
Characterization of the putative tryptophan synthase β-subunit from Mycobacterium tuberculosis
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DOI：
10.1093/abbs/gmp017
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发表时间：
2009-05-01
影响因子：
3.7
通讯作者：
Wang, Honghai
中科院分区：
文献类型：
--
作者：
Shen, Hongbo;Yang, Yanping;Wang, Honghai
耐药结核病的日益增多对控制这一疾病构成严重威胁。迫切需要开发新的结核病药物。色氨酸生物合成途径在结核分枝杆菌（Mycobacterium tuberculosis，Mtb）的生长和复制过程中起重要作用。色氨酸合成酶β亚基（TrpB）催化色氨酸生物合成途径的最后一步，可能成为结核病药物设计的潜在靶点。在这项研究中，我们过表达，纯化和其特征在于推定的TrpB编码基因Rv 1612的结核分枝杆菌H37 Rv。结果表明，Mtb His-TrpB的最佳酶活性是在pH 7.8，0.15 M Na+或0.18 M Mg 2+，37 ℃下。结构分析表明，Mtb TrpB具有典型的β/α桶结构。通过同源性建模和结构比对预测了被认为与酶辅因子吡哆醛-5 '-磷酸相互作用的氨基酸残基。这些残基在Mtb His-TrpB的催化活性中的作用通过定点诱变证实。这些结果为基于TrpB的药物设计提供了可靠的结构信息。
The increasing emergence of drug-resistant tuberculosis (TB) poses a serious threat to the control of this disease. It is in urgent need to develop new TB drugs. Tryptophan biosynthetic pathway plays an important role in the growth and replication of Mycobacterium tuberculosis (Mtb). The beta-subunit of tryptophan synthase (TrpB) catalyzes the last step of the tryptophan biosynthetic pathway, and it might be a potential target for TB drug design. In this study, we overexpressed, purified, and characterized the putative TrpB-encoding gene Rv1612 in Mtb H37Rv. Results showed that Mtb His-TrpB optimal enzymatic activity is at pH 7.8 with 0.15 M Na+ or 0.18 M Mg2+ at 37 degrees C. Structure analysis indicated that Mtb TrpB exhibited a typical beta/alpha barrel structure. The amino acid residues believed to interact with the enzyme cofactor pyridoxal-5'-phosphate were predicted by homology modeling and structure alignment. The role of these residues in catalytic activity of the Mtb His-TrpB was confirmed by site-directed mutagenesis. These results provided reassuring structural information for drug design based on TrpB.