Chitale S, Ehrt S, Kawamura I, Fujimura T, Shimono N, Anand N, Lu S, Cohen-Gould L, Riley L W
Department of Medicine, Weill Medical College of Cornell University New York, NY, USA.
Cell Microbiol. 2001 Apr;3(4):247-54. doi: 10.1046/j.1462-5822.2001.00110.x.
The ability to gain entry and resist the antimicrobial intracellular environment of mammalian cells is an essential virulence property of Mycobacterium tuberculosis. A purified recombinant protein expressed by a 1362 bp locus (mce1) in the M. tuberculosis genome promoted uptake into HeLa cells of polystyrene latex microspheres coated with the protein. N-terminus deletion constructs of Mce1 identified a domain located between amino acid positions 106 and 163 that was needed for this cell uptake activity. Mce1 contained hydrophobic stretches at the N-terminus predictive of a signal sequence, and colloidal gold immunoelectron microscopy indicated that the corresponding native protein is expressed on the surface of the M. tuberculosis organism. The complete M. tuberculosis genome sequence revealed that it contained four homologues of mce (mce1, mce2, mce3, mce4) and that they were all located within operons composed of genes arranged similarly at different locations in the chromosome. Recombinant Mce2, which had the highest level of identity (67%) to Mce1, was unable to promote the association of microspheres with HeLa cells. Although the exact function of Mce1 is still unknown, it appears to serve as an effector molecule expressed on the surface of M. tuberculosis that is capable of eliciting plasma membrane perturbations in non-phagocytic mammalian cells.
进入哺乳动物细胞并抵抗其抗菌细胞内环境的能力是结核分枝杆菌的一种基本毒力特性。结核分枝杆菌基因组中一个1362 bp位点（mce1）表达的纯化重组蛋白促进了包被该蛋白的聚苯乙烯乳胶微球被HeLa细胞摄取。Mce1的N端缺失构建体确定了一个位于氨基酸位置106至163之间的结构域，该结构域是这种细胞摄取活性所必需的。Mce1在N端含有预测信号序列的疏水片段，胶体金免疫电子显微镜显示相应的天然蛋白在结核分枝杆菌表面表达。结核分枝杆菌的完整基因组序列显示它包含四个mce同源物（mce1、mce2、mce3、mce4），并且它们都位于由在染色体不同位置以相似方式排列的基因组成的操纵子内。与Mce1具有最高同源性水平（67%）的重组Mce2无法促进微球与HeLa细胞的结合。尽管Mce1的确切功能仍然未知，但它似乎作为结核分枝杆菌表面表达的一种效应分子，能够在非吞噬性哺乳动物细胞中引起质膜扰动。
