结核分枝杆菌gyrB基因上三个天然突变对氟喹诺酮药物敏感性的影响研究  

Effect of Three Spontaneous Mutations in gyrB on the Susceptibility of Mycobacterium tuberculosis H37Rv to Fluoroquinolones

作　　者：崔振玲[1] 王洁[1] 陆俊梅[1] 黄晓辰[1] 胡忠义[1] 

机构地区：[1]同济大学医学院附属上海市肺科医院\上海市结核病(肺)重点实验室,上海200433

出　　处：《世界最新医学信息文摘》2012年第1期14-19,共6页World Latest Medicine Information Electronic Version

基　　金：教育部博士点新教师基金（20090072120049）

摘　　要：目的：分析研究gyrB基因上的三个天然突变住点（R485C、D500N和T539N）对结核分枝杆菌H37Rv氟喹诺酮药物敏感性的作用。方法：将野生型gyrB基因和突变型gyrB基因通过pVV16质粒电转导入结核分枝杆菌H37Rv中，并通过微孔板硝酸盐还原法检测重组子对三种氟喹诺酮类药物的MIC值。结果：携带有R485C、D500N和T539N的重组子时氟喹诺酮的抗性比野生型强（MIC值至少为野生型的2倍及以上）；其中携带D500N的重组子MIC值是野生型的8倍，携带R485C的重组子抗性较野生型变化最小。通过结核分枝杆菌DNA螺旋酶的3D模型分析显示，D500和T539位于氟喹诺酮与DNA结合的区域，而R483位于ATP酶和B亚基C末端的铰链区（非酶活性区）。结论：本研究首次研究显示gyrB上3个不同的天然突变可导致结核分枝杆菌对多种氟喹诺酮类药物敏感性的降低。Objective： The aim of this study was to examine the effects of three spontaneous mutations in gyrB （causing residue substitutions at R485C, D500N and T539N） on the susceptibility of Mycobacterium tuberculosis H37Rv （MTB H37Rv） to fluoroquinolones （FQs）. Methods： Wild type gyrB and the mutant genes were electro- transformed into MTB H37Rv using the pVV16 plasmid vector. The minimum inhibitory concentrations （MICs） of the recombinants were determined against three FQs （ofloxacin, levofloxacin and moxifloxacin） using a micro- plate nitrate reductase assay. Results： Recombinants bearing gyrB with the R485C, D500N and T539N substitu- tions were more resistant to the growth inhibitory effects of each of the FQs （MICs at least 2-fold greater than the bacteria containing wild type gyrB）. The FQ resistance of the recombinant bearing the D500N substituted gyrB was greatest （MIC was 8-fold greater than wild type gyrB）, while the recombinant bearing the R485C substituted gyrB showed least increase in resistance to FQs. The mutations were analysed structurally using a 3D-model of the MTB DNA gyrase catalytic core. Residues D500 and T539 are located in the quinolone-binding pocket of the DNA gyrase, while residue R485 is located in the hinge region between the ATPase and the Toprim domains of subunit B （i.e., not in the catalytic core）. Conclusions： This is the first study to show that three different spontane- ous mutations in gyrB （causing residue substitutions in subunit B of DNA gyrase and affecting FQ-binding） con- fer reduced susceptibility ofMTB H37Rv to multiple FQs.

关 键 词：医学微生物 结核分枝杆菌 氟喹诺酮 基因突变 

分 类 号：R446.5[医药卫生—诊断学]