Regulation of the Vibrio vulnificus hupA Gene by Temperature Alteration and Cyclic AMP Receptor Protein and Evaluation of Its Role in Virulence
Regulation of the Vibrio vulnificus hupA Gene by Temperature Alteration and Cyclic AMP Receptor Protein and Evaluation of Its Role in Virulence
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DOI：
10.1128/iai.01006-08
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发表时间：
2009-03-01
影响因子：
3.1
通讯作者：
Choi, Sang Ho
中科院分区：
文献类型：
--
作者：
Oh, Man Hwan;Lee, Sung Min;Choi, Sang Ho
在哺乳动物宿主体内，游离铁的可用性极其有限，而在宿主体内获取铁对于致病菌的成功感染至关重要。许多参与获取铁的基因的表达受到铁可利用性水平的调节，铁的调节是由Fur介导的。在这项研究中，创伤弧菌（Vibrio vulnificus）血红素受体蛋白HupA的细胞水平和HupA转录本在40℃下生长的细胞中比在30℃下生长的细胞中增加。结果表明，生长温度的变化以及铁的可用性是控制HupA基因表达的环境线索。研究了全局调控蛋白对hupA表达的影响，发现环AMP受体蛋白（CRP）在转录水平上激活hupA的表达。CRP通过直接结合hupA启动子P-hupA上游的DNA发挥作用，并且通过DNase I保护实验确定了位于转录起始位点上游174 bp的CRP结合位点。最后，hupA突变体在小鼠和组织培养中表现出毒性降低，在组织培养中，hupA突变体的生长受到损害，表明创伤弧菌的hupA对感染期间的生存和繁殖至关重要。
Availability of free iron is extremely limited in the mammalian host, and the acquisition of iron in the host is essential for successful infection by pathogenic bacteria. Expression of many genes involved in acquiring iron is regulated in response to the level of iron availability, and iron regulation is mediated by Fur. In this study, cellular levels of Vibrio vulnificus HupA, a heme receptor protein, and the hupA transcript were found to increase in cells grown at 40 degrees C compared to cells grown at 30 degrees C. The results suggested that change in growth temperature, in addition to iron availability, is an environmental cue controlling the expression of the hupA gene. The influence of global regulatory proteins on the expression of hupA was examined, and the cyclic AMP receptor protein (CRP) was found to activate the expression of hupA at the transcriptional level. CRP exerts its effects by directly binding to DNA upstream of the hupA promoter P-hupA, and a CRP binding site, centered at 174 bp upstream of the transcription start site, was identified by a DNase I protection assay. Finally, a hupA mutant showed reduced virulence in mice and in tissue cultures, in which growth of the hupA mutant was impaired, indicating that HupA of V. vulnificus is essential for survival and multiplication during infection.