Role of Vfr in regulating exotoxin A production by Pseudomonas aeruginosa
Role of Vfr in regulating exotoxin A production by Pseudomonas aeruginosa
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DOI：
10.1099/mic.0.028373-0
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发表时间：
2009-07-01
期刊：
影响因子：
2.8
通讯作者：
Hamood, Abdul N.
中科院分区：
文献类型：
--
作者：
Davinic, Marko;Carty, Nancy L.;Hamood, Abdul N.
铜绿假单胞菌外毒素A（ETA）的产生依赖于毒力因子调节因子Vfr。最近的证据表明铜绿假单胞菌铁饥饿σ因子PvdS也通过ETA调节基因regA增强ETA产生。利用vfr、regA和pvdS缺陷的突变体、单独过表达这些基因的质粒和lacZ转录/翻译融合质粒来检查vfr、regA和pvdS在调节铜绿假单胞菌ETA产生中的关系。在PAO Delta vfr中，ETA浓度和regA表达显著降低，但pvdS表达不受影响。Vfr的过表达在PAO Delta pvdS中产生了有限的ETA产生增加，但在PAO Delta regA中没有。此外，RegA或I的过表达不增强PAO Delta vfr中的ETA产生。RT-PCR分析表明，铁不影响PAO 1中vfr mRNA的积累。这些结果表明：（i）Vfr通过regA直接和间接增强PAO 1中的toxA表达，但不通过pvdS;（ii）vfr表达不受铁调节;和（iii）Vfr和PvdS在RegA存在下合作以实现最大水平的toxA表达。
Pseudomonas aeruginosa exotoxin A (ETA) production depends on the virulence-factor regulator Vfr. Recent evidence indicates that the P. aeruginosa iron-starvation sigma factor PvdS also enhances ETA production through the ETA-regulatory gene regA. Mutants defective in vfr, regA and pvdS, plasmids that overexpress these genes individually and lacZ transcriptional/translational fusion plasmids were utilized to examine the relationship between vfr, regA and pvdS in regulating P. aeruginosa ETA production. ETA concentration and regA expression were reduced significantly in PAO Delta vfr, but pvdS expression was not affected. Overexpression of Vfr produced a limited increase in ETA production in PAO Delta pvdS, but not PAO Delta regA. Additionally, overexpression of either RegA or l did not enhance ETA production in PAO Delta vfr. RT-PCR analysis showed that iron did not affect the accumulation of vfr mRNA in PAO1. These results suggest that: (i) Vfr enhances toxA expression in PAO1 both directly and indirectly through regA, but not through pvdS; (ii) vfr expression is not regulated by iron; and (iii) both Vfr and PvdS cooperate in the presence of RegA to achieve a maximum level of toxA expression.