Forst Steven, Boylan Brian
Department of Biological Sciences, University of Wisconsin, Milwaukee 53201, USA.
Antonie Van Leeuwenhoek. 2002 Aug;81(1-4):43-9. doi: 10.1023/a:1020517307743.
Xenorhabdus nematophila is an insect pathogen that forms a symbiotic association with the nematode, Steinernema carpocapsae. Xenorhabdus is carried into the insect host by the nematode, is released into the hemolymph and participates in killing the insect. The bacteria grow to high concentrations supporting the development of the nematode in the hemolymph. OmpR is a global regulatory protein involved in the regulation of porin genes, motility, acid tolerance and virulence in several enteric bacteria. To study the role of ompR in the lifecyle of XenorhabdIs, an ompR -minus strain was constructed. The ompR strain produced markedly reduced levels of the porin protein, OpnP and was both hypermotile and exhibited a hyperhemolysis phenotype. Inactivation of flhDC, the master regulator for flagella synthesis, eliminated hemolysin production in the ompR strain, suggesting that ompR regulates hemolysin production via flhDC. The ompR mutant strain was virulent towards insect hosts. However, when nematodes were grown on a mixture of the wild-type and the omnpR strain, only the wild-type strain was recovered indicating that ompR is required for competitive symbiotic interaction with the nematode. The role of ompR in the symbiosis between the bacterium and the nematode is under investigation.
嗜线虫致病杆菌是一种昆虫病原体，它与线虫小卷蛾斯氏线虫形成共生关系。嗜线虫致病杆菌由线虫携带进入昆虫宿主，释放到血淋巴中并参与杀死昆虫。细菌大量生长，支持线虫在血淋巴中的发育。OmpR是一种全局调节蛋白，参与多种肠道细菌中孔蛋白基因、运动性、耐酸性和毒力的调节。为了研究ompR在嗜线虫致病杆菌生命周期中的作用，构建了一个ompR缺失菌株。该ompR菌株产生的孔蛋白OpnP水平显著降低，并且具有高度运动性和高溶血表型。鞭毛合成的主要调节因子flhDC的失活消除了ompR菌株中的溶血素产生，这表明ompR通过flhDC调节溶血素的产生。ompR突变菌株对昆虫宿主具有毒性。然而，当线虫在野生型和ompR菌株的混合物上生长时，只回收了野生型菌株，这表明ompR是与线虫进行竞争性共生相互作用所必需的。ompR在细菌与线虫共生中的作用正在研究中。
