The fur-regulated gene encoding the alternative sigma factor PvdS is required for iron-dependent expression of the LysR-type regulator ptxR in Pseudomonas aeruginosa.
The fur-regulated gene encoding the alternative sigma factor PvdS is required for iron-dependent expression of the LysR-type regulator ptxR in Pseudomonas aeruginosa.
复制标题
铜绿假单胞菌中 LysR 型调节因子 ptxR 的铁依赖性表达需要编码替代 sigma 因子 PvdS 的毛皮调节基因。
DOI：
10.1128/jb.180.24.6784-6788.1998
复制
发表时间：
1998
影响因子：
3.2
通讯作者：
Hamood,AN
中科院分区：
文献类型：
--
作者：
Vasil,ML;Ochsner,UA;Johnson,Z;Colmer,JA;Hamood,AN
We previously identified a novel regulator of the exotoxin A gene (toxA) inPseudomonas aeruginosa, PtxR, that belongs to the LysR family of prokaryotic regulatory proteins. Preliminary data also suggest that PtxR affects the expression of siderophores inP. aeruginosa. BecausetoxAexpression and siderophore production in this organism are coordinately regulated by the ferric uptake regulator (Fur) and the Fur-regulated alternative sigma factor PvdS, regulation ofptxRitself in the context of these regulators was examined. RNase protection analyses ofptxRtranscription revealed that there are two independent transcription initiation sites (T1 and T2). While transcription from the promoter of T1 is constitutive throughout the growth cycle of PAO1, transcription from the second promoter (P2) is negatively affected by iron. Transcription from the P2 promoter is constitutive in afurmutant under microaerobic conditions but still iron regulated during aerobic growth. High concentrations (>100 nM) of the ferric uptake regulatory protein (Fur) failed to bind to either of the promoter regions ofptxRin either gel mobility shift assays or DNase I footprint experiments. These results indicate that Fur indirectly regulates the iron-dependent expression ofptxR. Iron-regulated transcription ofptxRfrom the P2 promoter, but not constitutive expression from the P1 promoter, was dependent on the Fur-regulated alternative sigma factor genepvdS, even under aerobic conditions. Consequently, there are two levels of iron-regulated expression ofptxR. The iron-regulated expression ofptxRunder microaerobic conditions from the P2 promoter ofptxRis mediated indirectly by Fur through the iron-regulated expression ofpvdS. In contrast,pvdS-mediated iron regulation ofptxRunder aerobic conditions is Fur independent.
