Sundin Charlotta, Wolfgang Matthew C, Lory Stephen, Forsberg Ake, Frithz-Lindsten Elisabet
Department of Medical Countermeasures, FOI NBC-Defence, S-901 82, Umeå, Sweden.
Microb Pathog. 2002 Dec;33(6):265-77. doi: 10.1006/mpat.2002.0534.
The type III secretion system (TTSS) of the opportunistic pathogen Pseudomonas aeruginosa enables the bacterium to deliver exoenzymes directly into the eukaryotic cell. In this study we have investigated the role of key factors involved in this process. We could demonstrate that the translocators PopB, PopD and PcrV are absolutely required for delivery of Exoenzyme S into host cells. By analyzing different Tfp (type IV pili) mutants we could establish a correlation between the frequency of bacteria binding to the host cell and the levels of translocated ExoS, thereby verifying that the process is contact dependent. However, there was no absolute requirement for the Tfp per se, since the pilus could be substituted with a different type of adhesin, the non-fimbrial adhesin pH6 antigen of Yersinia pestis. Taken together, our results demonstrate that binding to establish close contact between the type III secretion organelle and the host cell is essential for translocation, while the additional activities of Tfp are not essential for the delivery of TTSS proteins.
机会致病菌铜绿假单胞菌的III型分泌系统（TTSS）可使该细菌将外切酶直接输送到真核细胞中。在本研究中，我们调查了参与此过程的关键因子的作用。我们能够证明，转运蛋白PopB、PopD和PcrV是将外切酶S输送到宿主细胞所绝对必需的。通过分析不同的IV型菌毛（Tfp）突变体，我们能够确定细菌与宿主细胞结合频率与转运的ExoS水平之间的相关性，从而证实该过程是接触依赖性的。然而，对Tfp本身并没有绝对的需求，因为菌毛可以被另一种粘附素替代，即鼠疫耶尔森菌的非菌毛粘附素pH6抗原。综上所述，我们的结果表明，III型分泌细胞器与宿主细胞之间建立紧密接触的结合对于转运至关重要，而Tfp的其他活性对于TTSS蛋白的输送并非必不可少。
