Singh Ramandeep, Rao Vivek, Shakila H, Gupta Radhika, Khera Aparna, Dhar Neeraj, Singh Amit, Koul Anil, Singh Yogendra, Naseema M, Narayanan P R, Paramasivan C N, Ramanathan V D, Tyagi Anil K
Department of Biochemistry, University of Delhi South campus, Benito Juarez Road, New Delhi-110021, India.
Mol Microbiol. 2003 Nov;50(3):751-62. doi: 10.1046/j.1365-2958.2003.03712.x.
Protein tyrosine kinases and tyrosine phosphatases from several bacterial pathogens have been shown to act as virulence factors by modulating the phosphorylation and dephosphorylation of host proteins. The identification and characterization of two tyrosine phosphatases namely MptpA and MptpB from Mycobacterium tuberculosis has been reported earlier. MptpB is secreted by M. tuberculosis into extracellular mileu and exhibits a pH optimum of 5.6, similar to the pH of the lysosomal compartment of the cell. To determine the role of MptpB in the pathogenesis of M. tuberculosis, we constructed a mptpB mutant strain by homologous recombination and compared the ability of parent and the mutant strain to survive intracellularly. We show that disruption of the mptpB gene impairs the ability of the mutant strain to survive in activated macrophages and guinea pigs but not in resting macrophages suggesting the importance of its role in the host-pathogen interaction. Infection of guinea pigs with the mutant strain resulted in a 70-fold reduction in the bacillary load of spleens in infected animals as compared with the bacillary load in animals infected with the parental strain. Upon reintroduction of the mptpB gene into the mutant strain, the complemented strain was able to establish infection and survive in guinea pigs at rates comparable to the parental strain. These observations demonstrate a role of MptpB in the pathogenesis of M. tuberculosis.
几种细菌病原体的蛋白酪氨酸激酶和酪氨酸磷酸酶已被证明可通过调节宿主蛋白的磷酸化和去磷酸化作用来充当毒力因子。此前已有报道对来自结核分枝杆菌的两种酪氨酸磷酸酶MptpA和MptpB进行了鉴定和表征。MptpB由结核分枝杆菌分泌到细胞外环境中，其最适pH值为5.6，与细胞溶酶体区室的pH值相似。为了确定MptpB在结核分枝杆菌致病机制中的作用，我们通过同源重组构建了一个mptpB突变株，并比较了亲本菌株和突变株在细胞内存活的能力。我们发现mptpB基因的破坏损害了突变株在活化巨噬细胞和豚鼠中存活的能力，但在静止巨噬细胞中则不然，这表明其在宿主-病原体相互作用中的作用很重要。与感染亲本菌株的动物相比，用突变株感染豚鼠导致感染动物脾脏中的细菌载量降低了70倍。将mptpB基因重新导入突变株后，互补菌株能够像亲本菌株一样在豚鼠中建立感染并存活。这些观察结果证明了MptpB在结核分枝杆菌致病机制中的作用。
