Department of Biochemistry, National JALMA Institute for Leprosy & Other Mycobacterial Diseases (ICMR), Agra, India.
Indian J Med Res. 2010 Oct;132:400-8.
BACKGROUND & OBJECTIVES: The resistance of Mycobacterium tuberculosis to streptomycin, a core drug for treatment of category II tuberculosis (TB) has posed a major challenge to the health providers as well as research workers worldwide and has severely compromised the therapeutic options. A significant proportion of streptomycin resistant M. tuberculosis isolates failed to show mutations in conventional targets like rpsL and rrs. Although efflux, permeability, etc. are also known to contribute, yet a substantial proportion of isolates remains resistant suggesting involvement of other unknown mechanism. A resistant isolate may show altered gene as well as protein expression under drug induced conditions and a whole cell proteome analysis under induced conditions might help in further understanding the mechanisms of drug resistance. The present study was therefore designed with the objective to identify proteins related to streptomycin resistance in M. tuberculosis isolate grown in presence and absence of streptomycin (SM).
A clinical isolate of M. tuberculosis from Mycobacterial Repository Centre at the Institute (NJIL & OMD), Agra was grown in Sauton's medium for 36 h with/without subinhibitory concentration of the drug (2 μg/ml) and the cell lysate of isolates was prepared by sonication and centrifugation. Two-dimensional (2D) gel electrophoresis was employed to study the protein profile. The selected proteins were finally identified by MALDI-TOF mass spectrometry.
Our study revealed eight inducible proteins (DnaK, fabG4, DNA-binding, hypothetical, two 14 kDa antigen and two 10 kDa chaperonin) that were upregulated in the presence of drug.
INTERPRETATION & CONCLUSION: This preliminary study has thrown light on whether or not and how the resistant isolate responds to streptomycin at its non-toxic but sub-inhibitory concentration. An in-depth study of the upregulated proteins will give an insight into probable sites of drug action other than established primary sites.
结核分枝杆菌（Mycobacterium tuberculosis）对链霉素（一种治疗 II 型结核病（TB）的核心药物）的耐药性，对全球卫生提供者和研究人员构成了重大挑战，并严重影响了治疗选择。相当一部分耐药结核分枝杆菌分离株在传统靶点（如 rpsL 和 rrs）中未显示突变。尽管外排、通透性等也被认为有贡献，但仍有相当一部分分离株耐药，这表明存在其他未知机制。耐药分离株在药物诱导条件下可能表现出改变的基因和蛋白表达，而诱导条件下的全细胞蛋白质组分析可能有助于进一步了解耐药机制。因此，本研究旨在鉴定在有/无链霉素（SM）存在下生长的结核分枝杆菌分离株中与链霉素耐药相关的蛋白质。
从印度尼西亚结核病和肺病研究所（NJIL & OMD）的分枝杆菌库中获得结核分枝杆菌临床分离株，在 Sauton 培养基中培养 36 小时，有/无药物亚抑菌浓度（2μg/ml），通过超声和离心制备分离株的细胞裂解物。采用二维（2D）凝胶电泳研究蛋白质谱。最后通过 MALDI-TOF 质谱鉴定选定的蛋白质。
我们的研究揭示了 8 种诱导蛋白（DnaK、fabG4、DNA 结合、假设、两种 14kDa 抗原和两种 10kDa 伴侣蛋白）在药物存在时上调。
这项初步研究阐明了耐药分离株是否以及如何在非毒性但亚抑菌浓度下对链霉素作出反应。对上调蛋白的深入研究将深入了解除既定主要作用部位以外可能的药物作用部位。
