EsxA membrane-permeabilizing activity plays a key role in mycobacterial cytosolic translocation and virulence: effects of single-residue mutations at glutamine 5.
EsxA membrane-permeabilizing activity plays a key role in mycobacterial cytosolic translocation and virulence: effects of single-residue mutations at glutamine 5.
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EsxA 膜透化活性在分枝杆菌胞质易位和毒力中发挥关键作用：谷氨酰胺 5 处单残基突变的影响。
DOI：
10.1038/srep32618
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发表时间：
2016
影响因子：
4.6
通讯作者：
Jianjun Sun
中科院分区：
文献类型：
--
作者：
Qi Zhang;王德成;Guozhong Jiang;Wei Liu;Qing Deng;Xiujun Li;Wei Qian;Hugues Ouellet;Jianjun Sun
EsxA 是结核分枝杆菌 (Mtb) 毒力所必需的，并且在吞噬体破裂和易位至巨噬细胞胞浆中发挥重要作用。最近的生化研究表明 EsxA 是一种膜透化蛋白。然而，缺乏将 EsxA 膜透化活性与 Mtb 胞质易位和毒力联系起来的证据。在这里，我们发现谷氨酰胺 5 (Q5) 的突变可以上调或下调 EsxA 膜透化活性。突变Q5K显着降低了膜透化活性，而Q5V则增强了该活性。通过利用单残基突变，我们使用海分枝杆菌 (Mm) 和 Mtb 的 esxA/esxB 敲除菌株测试了 EsxA 膜透化活性对分枝杆菌毒力和胞质易位的影响。与野生型（WT）相比，Q5K突变体表现出显着减弱的毒力，小鼠巨噬细胞的细胞内存活和细胞毒性以及斑马鱼胚胎的感染证明了这一点。 Q5K突变体的毒力减弱与胞质易位受损相关。相反，Q5V突变体的胞质易位显着增加，并表现出总体毒力增加。这项研究提供了令人信服的证据，证明 EsxA 因其胞质易位所需的膜透化活性而有助于分枝杆菌毒力。
EsxA is required for virulence ofMycobacterium tuberculosis (Mtb) and plays an essential role in phagosome rupture and translocation to the cytosol of macrophages. Recent biochemical studies have demonstrated that EsxA is a membrane-permeabilizing protein. However, evidence that link EsxA membrane-permeabilizing activity toMtbcytosolic translocation and virulence is lacking. Here we found that mutations at glutamine 5 (Q5) could up or down regulate EsxA membrane-permeabilizing activity. The mutation Q5K significantly diminished the membrane-permeabilizing activity, while Q5V enhanced the activity. By taking advantage of the single-residue mutations, we tested the effects of EsxA membrane-permeabilizing activity on mycobacterial virulence and cytosolic translocation using theesxA/esxBknockout strains ofMycobacterium marinum (Mm) andMtb. Compared to wild type (WT), the Q5K mutant exhibited significantly attenuated virulence, evidenced by intracellular survival and cytotoxicity in mouse macrophages as well as infection of zebra fish embryos. The attenuated virulence of the Q5K mutant was correlated to the impaired cytosolic translocation. On the contrary, the Q5V mutant had a significantly increased cytosolic translocation and showed an overall increased virulence. This study provides convincing evidence that EsxA contributes to mycobacterial virulence with its membrane-permeabilizing activity that is required for cytosolic translocation.