Stainier I, Bleves S, Josenhans C, Karmani L, Kerbourch C, Lambermont I, Tötemeyer S, Boyd A, Cornelis G R
Microbial Pathogenesis Unit, Christian de Duve Institute of Cellular Pathology (ICP) and Faculté de Médecine, Université Catholique de Louvain, B-1200 Brussels, Belgium.
Mol Microbiol. 2000 Sep;37(5):1005-18. doi: 10.1046/j.1365-2958.2000.02026.x.
The Yersinia Ysc apparatus is made of more than 20 proteins, 11 of which have homologues in many type III systems. Here, we characterize YscP from Yersinia enterocolitica. This 515-residue protein has a high proline content, a large tandem repetition and a slow migration in SDS-PAGE. Unlike the products of neighbouring genes, it has a counterpart only in Pseudomonas aeruginosa and it varies even between Yersinia Ysc machineries. An yscPDelta97-465 mutant was unable to secrete any Yop, even under conditions overcoming feedback inhibition of Yop synthesis. Interestingly, a cloned yscPDelta57-324 from Yersinia pestis introduced in the yscPDelta97-465 mutant can sustain a significant Yop secretion and thus partially complemented the mutation. This explains the leaky phenotype observed with the yscP mutant of Y. pestis. In accordance with this secretion deficiency, YscP is required for the delivery of Yop effectors into macrophages. Mechanical shearing, immunolabelling and electron microscopy experiments showed that YscP is exposed at the bacterial surface when bacteria are incubated at 37 degrees C in the presence of Ca2+ and thus do not secrete Yops. At 37 degrees C, when Ca2+ ions are chelated, YscP is released like a Yop protein. We conclude that YscP is a part of the Ysc injectisome which is localized at the bacterial surface and is destabilized by Ca2+ chelation.
耶尔森氏菌的Ysc分泌装置由20多种蛋白质组成，其中11种在许多III型系统中都有同源物。在此，我们对小肠结肠炎耶尔森氏菌的YscP进行了表征。这种含有515个氨基酸残基的蛋白质脯氨酸含量高，有大量串联重复序列，在SDS-PAGE中迁移缓慢。与相邻基因的产物不同，它仅在铜绿假单胞菌中有对应物，甚至在不同的耶尔森氏菌Ysc机制之间也存在差异。一个yscPΔ97 - 465突变体即使在克服Yop合成反馈抑制的条件下也无法分泌任何Yop。有趣的是，将来自鼠疫耶尔森氏菌的克隆yscPΔ57 - 324导入yscPΔ97 - 465突变体中能够维持显著的Yop分泌，从而部分弥补了该突变。这解释了在鼠疫耶尔森氏菌的yscP突变体中观察到的渗漏表型。根据这种分泌缺陷，将Yop效应蛋白递送至巨噬细胞需要YscP。机械剪切、免疫标记和电子显微镜实验表明，当细菌在37℃、存在Ca2+的条件下培养时，YscP暴露于细菌表面，因此不分泌Yop。在37℃，当Ca2+离子被螯合时，YscP像Yop蛋白一样被释放出来。我们得出结论，YscP是Ysc注射体的一部分，它定位于细菌表面，并因Ca2+螯合而不稳定。
