Lysophospholipase A activity of Pseudomonas aeruginosa type III secretory toxin ExoU.
Lysophospholipase A activity of Pseudomonas aeruginosa type III secretory toxin ExoU.
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DOI：
10.1016/j.bbrc.2004.02.050
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发表时间：
2004-04
影响因子：
3.1
通讯作者：
Miki Tamura;T. Ajayi;L. Allmond;Kiyoshi Moriyama;J. Wiener‐Kronish;T. Sawa
中科院分区：
文献类型：
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作者：
Miki Tamura;T. Ajayi;L. Allmond;Kiyoshi Moriyama;J. Wiener‐Kronish;T. Sawa
铜绿假单胞菌肺炎的急性肺损伤主要依赖于通过 III 型分泌系统直接递送至真核细胞的 ExoU。最近的研究表明ExoU具有脂肪酶活性，并且ExoU的细胞毒性依赖于其patatin样磷脂酶结构域。我们研究了 ExoU 的磷脂酶 A (PLA) 活性。与 BEAS-2B 细胞裂解物预孵育的 ExoU（而非非催化 ExoU-S142A）显示不依赖 Ca2+ 的 PLA2 活性微弱增加。当激活的ExoU与分泌型PLA2混合时，观察到更多的磷脂酶活性，表明ExoU具有溶血磷脂酶A（lysoPLA）活性。还观察到 lysoPLA 活性显着增加。甘油增强了这种活性，iPLA2 抑制剂抑制了 ExoU 的 lysoPLA 活性。我们的结果表明，ExoU 具有有效的 lysoPLA 活性，需要催化活性位点 Ser142 和未知的真核细胞因子的存在才能激活。
Acute lung injury in Pseudomonas aeruginosa pneumonia depends primarily on ExoU that is delivered directly into the eukaryotic cell via the type III secretion system. Recent studies demonstrated that ExoU has lipase activity, and that the cytotoxicity of ExoU is dependent on its patatin-like phospholipase domain. We investigated the phospholipase A (PLA) activity of ExoU. ExoU, but not non-catalytic ExoU-S142A, preincubated with the BEAS-2B cell lysate showed a weak increase of Ca2+-independent PLA2activity. When activated ExoU was mixed with secretory type PLA2, more phospholipase activity was observed, suggesting that ExoU has lysophospholipase A (lysoPLA) activity. A significant increase in lysoPLA activity was also observed. Glycerol enhanced this activity and inhibitors of iPLA2suppressed ExoU’s lysoPLA activity. Our results suggest that ExoU has a potent lysoPLA activity that requires the presence of the catalytically active site Ser142with an unknown eukaryotic cell factor(s) for its activation.