Zhang H, Bi L-J, Li C-Y, Sun Z-G, Deng J-Y, Zhang Xian-En
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
J Int Med Res. 2009 Sep-Oct;37(5):1430-5. doi: 10.1177/147323000903700517.
This study was designed to investigate the presence of mutations in the pncA gene, minimum inhibitory concentrations and pyrazinamidase activity of pyrazinamide-resistant Mycobacterium tuberculosis. In total, 47 M. tuberculosis clinical isolates from a local region of China were assayed. Pyrazinamidase activity was measured by pyrazinamide deamination to pyrazinoic acid and ammonia, and a 721 bp region, including the entire pncA open-reading frame, 104 bp of the upstream sequence and 59 bp of the downstream sequence, was determined by DNA sequencing of purified polymerase chain reaction products. Of the 47 isolates resistant to pyrazinamide, 44 lost pyrazinamidase activity and had pncA mutations that occurred mainly near pyrazinamidase's active or metal ion binding sites; nine of them have not been reported previously. Three pyrazinamide-resistant isolates carried the wild-type pncA sequence and retained pyrazinamidase activity. These results show the molecular mechanism of pyrazinamide resistance in China and may also contribute towards the prevention of tuberculosis in China.
本研究旨在调查耐吡嗪酰胺结核分枝杆菌的pncA基因突变情况、最低抑菌浓度及吡嗪酰胺酶活性。共检测了来自中国某局部地区的47株结核分枝杆菌临床分离株。通过测定吡嗪酰胺脱氨生成吡嗪酸和氨来检测吡嗪酰胺酶活性，通过对纯化的聚合酶链反应产物进行DNA测序，确定了一个721 bp的区域，包括整个pncA开放阅读框、104 bp的上游序列和59 bp的下游序列。在47株耐吡嗪酰胺的分离株中，44株失去了吡嗪酰胺酶活性且发生了pncA基因突变，这些突变主要发生在吡嗪酰胺酶的活性或金属离子结合位点附近；其中9个突变此前未见报道。3株耐吡嗪酰胺分离株携带野生型pncA序列并保留了吡嗪酰胺酶活性。这些结果揭示了中国耐吡嗪酰胺结核分枝杆菌的分子机制，也可能有助于中国的结核病防治工作。
