Bacillus cereus Fur regulates iron metabolism and is required for full virulence
Bacillus cereus Fur regulates iron metabolism and is required for full virulence
复制标题
DOI：
10.1099/mic.0.27744-0
复制
发表时间：
2005-02-01
期刊：
影响因子：
2.8
通讯作者：
Ellar, DJ
中科院分区：
文献类型：
--
作者：
Harvie, DR;Vílchez, S;Ellar, DJ
在蜡样芽孢杆菌中发现了枯草芽孢杆菌的同源基因并进行了鉴定。克隆基因的预测氨基酸序列与转录调控因子Fur家族的其他成员高度相似。蜡样芽孢杆菌皮毛基因被证明可以部分补充大肠杆菌皮毛突变体。纯化的蜡样芽孢杆菌皮毛以金属依赖的方式特异性地与枯草芽孢杆菌毛皮盒同源的19bp DNA序列结合。通过对现有蜡样芽孢杆菌基因组数据的分析，发现许多基因在启动子区域含有预测的Fur box序列。据预测，其中许多基因在细菌铁摄取和代谢中起作用，但也有一些基因在毒力中起作用。铁和铁对铁载体生物合成操纵子的调节在β -半乳糖苷酶测定中得到证实。用卡那霉素抗性盒破坏的拷贝替换染色体基因，构建了蜡样芽孢杆菌零株。发现Deltafur突变体组成性表达铁载体，细胞内铁积累水平约为野生型的三倍，并且对过氧化氢敏感。在昆虫感染模型中，发现fur null菌株的毒力显著减弱，突出了fur在该病原体的毒力中发挥的重要作用。
A homologue of the Bacillus subtilis fur gene was identified in Bacillus cereus and characterized. The predicted amino acid sequence of the cloned gene was found to be highly similar to other members of the Fur family of transcriptional regulators. The B. cereus fur gene was shown to partially complement an Escherichia coli fur mutant. Purified B. cereus Fur bound specifically to a 19 bp DNA sequence homologous to the B. subtilis Fur box in a metal-dependent manner. Analysis of the available B. cereus genome data identified a number of genes which contain predicted Fur box sequences in the promoter region. Many of these genes are predicted to play a role in bacterial iron uptake and metabolism, but several have also been implicated as having a role in virulence. Fur and iron regulation of a siderophore biosynthesis operon was confirmed in a beta-galactosidase assay. A B. cereus fur null strain was constructed by allelic replacement of the chromosomal gene with a copy disrupted with a kanamycin resistance cassette. The Deltafur mutant was found to constitutively express siderophores, to accumulate iron intracellularly to a level approximately threefold greater than the wild-type, and to be hypersensitive to hydrogen peroxide. In an insect infection model, the virulence of the fur null strain was found to be significantly attenuated, highlighting the essential role played by Fur in the virulence of this pathogen.