Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada.
PLoS Pathog. 2012 Feb;8(2):e1002523. doi: 10.1371/journal.ppat.1002523. Epub 2012 Feb 2.
The eukaryotic cytoskeleton is essential for structural support and intracellular transport, and is therefore a common target of animal pathogens. However, no phytopathogenic effector has yet been demonstrated to specifically target the plant cytoskeleton. Here we show that the Pseudomonas syringae type III secreted effector HopZ1a interacts with tubulin and polymerized microtubules. We demonstrate that HopZ1a is an acetyltransferase activated by the eukaryotic co-factor phytic acid. Activated HopZ1a acetylates itself and tubulin. The conserved autoacetylation site of the YopJ / HopZ superfamily, K289, plays a critical role in both the avirulence and virulence function of HopZ1a. Furthermore, HopZ1a requires its acetyltransferase activity to cause a dramatic decrease in Arabidopsis thaliana microtubule networks, disrupt the plant secretory pathway and suppress cell wall-mediated defense. Together, this study supports the hypothesis that HopZ1a promotes virulence through cytoskeletal and secretory disruption.
真核细胞骨架对于结构支撑和细胞内运输至关重要，因此是动物病原体的常见靶标。然而，目前还没有证据表明植物病原体效应物能够特异性靶向植物细胞骨架。在这里，我们证明了丁香假单胞菌 III 型分泌效应物 HopZ1a 与微管蛋白和聚合微管相互作用。我们证明 HopZ1a 是一种由真核辅助因子植酸激活的乙酰转移酶。激活的 HopZ1a 自身和微管蛋白发生乙酰化。YopJ / HopZ 超家族的保守自身乙酰化位点 K289 在 HopZ1a 的无毒和毒性功能中都起着关键作用。此外，HopZ1a 需要其乙酰转移酶活性才能导致拟南芥微管网络急剧减少，破坏植物分泌途径并抑制细胞壁介导的防御。总之，这项研究支持了这样一种假设，即 HopZ1a 通过细胞骨架和分泌的破坏来促进毒力。
