Hartland E L, Green S P, Phillips W A, Robins-Browne R M
Department of Microbiology, University of Melbourne, Parkville, Victoria, Australia.
Infect Immun. 1994 Oct;62(10):4445-53. doi: 10.1128/iai.62.10.4445-4453.1994.
The respiratory burst is a key element of the bactericidal armamentarium of phagocytes. In this study we have shown that a virulent strain of Yersinia enterocolitica serogroup O:9 completely inhibited the ability of murine bone marrow-derived macrophages to mount a respiratory burst in response to stimulation by zymosan. This property of the bacterium was abrogated by curing the strain of its 71.5-kb virulence plasmid and by transposon mutagenesis of the plasmid-borne yopD gene. Derivatives of the bacterium which were unable to inhibit the respiratory burst were also less able to disrupt cytoskeletal actin and to resist phagocytosis. yopD mutants also showed an impaired ability to dephosphorylate phosphotyrosine residues in macrophage proteins and were completely avirulent for mice. All of these defects were fully or partly restored by trans-complementation of a yopD mutant with a cloned yopD gene. The results of this study and those of previous work with YopD (R. Rosqvist, A. Forsberg, and H. Wolf-Watz, Infect. Immun. 59:4562-4569, 1991) suggest that YopD functions chiefly by facilitating the transport of virulence plasmid-encoded proteins, such as YopE, a cytotoxin, and YopH, a protein tyrosine phosphatase, across the cytoplasmic membrane to their targets within host cells. The combined action of these Yops on cytoplasmic proteins, especially actin, could explain the effects of virulent Y. enterocolitica on macrophage morphology, phagocytic capacity, and respiratory burst activity, all of which rely on cytoskeletal integrity to function normally.
呼吸爆发是吞噬细胞杀菌武器库的关键要素。在本研究中，我们发现小肠结肠炎耶尔森菌O:9血清型的一个强毒株能完全抑制小鼠骨髓来源巨噬细胞对酵母聚糖刺激产生呼吸爆发的能力。通过去除该菌株的71.5 kb毒力质粒以及对质粒携带的yopD基因进行转座子诱变，该细菌的这一特性被消除。不能抑制呼吸爆发的该细菌衍生物破坏细胞骨架肌动蛋白和抵抗吞噬作用的能力也较弱。yopD突变体在使巨噬细胞蛋白中的磷酸酪氨酸残基去磷酸化方面也表现出受损能力，并且对小鼠完全无毒力。通过用克隆的yopD基因对yopD突变体进行反式互补，所有这些缺陷都得到了全部或部分恢复。本研究结果以及先前关于YopD的研究结果（R. Rosqvist、A. Forsberg和H. Wolf-Watz，《感染与免疫》59:4562 - 4569，1991）表明，YopD主要通过促进毒力质粒编码蛋白的转运来发挥作用，这些蛋白如细胞毒素YopE和蛋白酪氨酸磷酸酶YopH，通过细胞质膜转运到宿主细胞内的靶点。这些Yop蛋白对细胞质蛋白，尤其是肌动蛋白的联合作用，可以解释强毒小肠结肠炎耶尔森菌对巨噬细胞形态、吞噬能力和呼吸爆发活性的影响，所有这些都依赖于细胞骨架的完整性来正常发挥功能。
