Comparison of the Moonlighting Actions of the Two Highly Homologous Chaperonin 60 Proteins of Mycobacterium tuberculosis
Comparison of the Moonlighting Actions of the Two Highly Homologous Chaperonin 60 Proteins of Mycobacterium tuberculosis
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DOI：
10.1128/iai.01379-09
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发表时间：
2010-07-01
影响因子：
3.1
通讯作者：
Henderson, Brian
中科院分区：
文献类型：
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作者：
Cehovin, Ana;Coates, Anthony R. M.;Henderson, Brian
有证据表明，结核分枝杆菌的两种伴侣蛋白(Cpn60.1和Cpn60.2)具有兼职作用，可能与结核病的病理有关。我们研究了结核分枝杆菌和感染的巨噬细胞释放Cpn60.1，并在一系列基于细胞的检测中比较了重组Cpn60.1和Cpn60.2，以确定这些高度同源的蛋白质的作用有多相似。我们现在确定CPN类似于：(I)Cpn60.1，正如Cpn60.2所示，是由结核分枝杆菌在培养中释放的，当细菌处于静止但未激活的巨噬细胞时，Cpn60.1进一步释放；(Ii)与脂多糖相比，这两种蛋白质都只显示MyD88诱导促炎细胞因子产生的部分需要。然而，我们也发现了CPN在细胞作用上的主要差异。(1)Cpn60.2比Cpn60.1对全血白细胞有更强的刺激作用，是唯一能诱导肿瘤坏死因子α合成的刺激因子。(Ii)Cpn60.1结合了约90%的循环单核细胞，而Cpn60.2结合了这些细胞的50%。这两种伴侣蛋白都与不同的细胞表面受体结合，而在TLR4(-/-)小鼠中，这两种蛋白对单核细胞的激活都被完全取消，尽管Cpn60.2也显示出对TLR2的显著需求。最后，在体外人肉芽肿实验中，一个缺乏cpn60.1但含有完整cpn60.2的等位基因突变体在产生多核巨细胞方面受到严重抑制。这些结果清楚地表明，尽管有显著的序列同源性，结核分枝杆菌Cpn60蛋白与人或小鼠巨噬细胞以不同的方式相互作用。
Evidence is emerging that the two chaperonin (Cpn) 60 proteins of Mycobacterium tuberculosis, Cpn60.1 and Cpn60.2, have moonlighting actions that may contribute to the pathology of tuberculosis. We studied the release of Cpn60.1 from M. tuberculosis and infected macrophagelike cells and compared recombinant Cpn60.1 and Cpn60.2 in a range of cell-based assays to determine how similar the actions of these highly homologous proteins are. We now establish that Cpns are similar as follows: (i) Cpn60.1, as it has been shown for Cpn60.2, is released by M. tuberculosis in culture, and Cpn60.1 is furthermore released when the bacterium is in quiescent, but not activated, macrophagelike cells, and (ii) both proteins only showed a partial requirement for MyD88 for the induction of proinflammatory cytokine production compared to lipopolysaccharide. However, we also found major differences in the cellular action of Cpns. (i) Cpn60.2 proved to be a more potent stimulator of whole blood leukocytes than Cpn60.1 and was the only one to induce tumor necrosis factor alpha synthesis. (ii) Cpn60.1 bound to ca. 90% of circulating monocytes compared to Cpn60.2, which bound < 50% of these cells. Both chaperonins bound to different cell surface receptors, while monocyte activation by both proteins was completely abrogated in TLR4(-/-) mice, although Cpn60.2 also showed significant requirement for TLR2. Finally, an isogenic mutant lacking cpn60.1, but containing intact cpn60.2, was severely inhibited in generating multinucleate giant cells in an in vitro human granuloma assay. These results clearly show that, despite significant sequence homology, M. tuberculosis Cpn60 proteins interact in distinct ways with human or murine macrophages.