A single Photorhabdus gene, makes caterpillars floppy (mcf), allows Escherichia coli to persist within and kill insects
A single Photorhabdus gene, makes caterpillars floppy (mcf), allows Escherichia coli to persist within and kill insects
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DOI：
10.1073/pnas.102068099
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发表时间：
2002-08-06
影响因子：
11.1
通讯作者：
Ffrench-Constant, RH
中科院分区：
文献类型：
--
作者：
Daborn, PJ;Waterfield, N;Ffrench-Constant, RH
光habdus luminesens是一种具有交替致病和共生生活方式的细菌，代表了与毒力和共生相关的新基因的来源。这种昆虫病原体与入侵昆虫的线虫“共生”。因此，这种细菌与昆虫病原线虫共生，但从线虫释放到昆虫血液系统后就会致病。在昆虫体内，细菌既需要避免肽和细胞（血细胞）介导的免疫反应，也需要杀死宿主，宿主随后成为细菌和线虫繁殖的储存库。然而，光habdus逃避昆虫免疫系统并杀死宿主的机制尚不清楚。在这里，我们展示了一个大的光habdus基因，使毛虫松软（mcf），足以让大肠杆菌在昆虫体内持续存在并杀死昆虫。预测的高分子量Mcf毒素与其他已知的蛋白质序列几乎没有相似性，但携带BH3结构域并引发昆虫血细胞和中肠上皮细胞的凋亡。
Photorhabdus luminescens, a bacterium with alternate pathogenic and symbiotic phases of its lifestyle, represents a source of novel genes associated with both virulence and symbiosis. This entomopathogen lives in a "symbiosis of pathogens" with nematodes that invade insects. Thus the bacteria are symbiotic with entomopathogenic nematodes but become pathogenic on release from the nematode into the insect blood system. Within the insect, the bacteria need to both avoid the peptide- and cellular- (hemocyte) mediated immune response and also to kill the host, which then acts as a reservoir for bacterial and nematode reproduction. However, the mechanisms whereby Photorhabdus evades the insect immune system and kills the host are unclear. Here we show that a single large Photorhabdus gene, makes caterpillars floppy (mcf), is sufficient to allow Esherichia coli both to persist within and kill an insect. The predicted high molecular weight Mcf toxin has little similarity to other known protein sequences but carries a BH3 domain and triggers apoptosis in both insect hemocytes and the midgut epithelium.