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首页> 外文期刊>Journal of bacteriology >The Ornibactin Biosynthesis and Transport Genes of Burkholderia cenocepacia Are Regulated by an Extracytoplasmic Function σ Factor Which Is a Part of the Fur Regulon
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The Ornibactin Biosynthesis and Transport Genes of Burkholderia cenocepacia Are Regulated by an Extracytoplasmic Function σ Factor Which Is a Part of the Fur Regulon

机译：Burkholderia cenocepacia的Ornibactin生物合成和转运基因受胞外功能σ因子调节，该因子是毛发调节子的一部分

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Burkholderia cenocepacia mutants that fail to produce the siderophore ornibactin were obtained following mutagenesis with mini-Tn5Tp. These mutants were shown to be growth restricted under conditions of iron depletion. In eight of the mutants, the transposon had integrated into one of two genes, orbI and orbJ, encoding nonribosomal peptide synthetases. In the other mutant, the transposon had inserted into an open reading frame, orbS, located upstream from orbI. The polypeptide product of orbS exhibits a high degree of similarity to the Pseudomonas aeruginosa extracytoplasmic function (ECF) σ factor PvdS but possesses an N-terminal extension of approximately 29 amino acids that is not present in PvdS. Three predicted OrbS-dependent promoters were identified within the ornibactin gene cluster, based on their similarity to PvdS-dependent promoters. The iron-regulated activity of these promoters was shown to require OrbS. Transcription of the orbS gene was found to be under the control of an iron-regulated σ70-dependent promoter. This promoter, but not the OrbS-dependent promoters, was shown to be a target for repression by the global regulator Fur. Our results demonstrate that production of ornibactin by B. cenocepacia in response to iron starvation requires transcription of an operon that is dependent on the Fur-regulated ECF σ factor gene orbS. A mechanism is also proposed for the biosynthesis of ornibactin.
机译：mini-Tn 5 Tp诱变后获得了不能产生铁载体鸟氨酸的 Burkholderia cenocepacia 突变体。这些突变体在铁耗竭的条件下显示出生长受限。在八个突变体中，转座子已整合到两个编码非核糖体肽合成酶的基因 orbI 和 orbJ 中的一个。在另一个突变体中，转座子插入了一个位于 orbI 上游的开放阅读框 orbS 中。 orbS 的多肽产物与铜绿假单胞菌胞浆外功能（ECF）σ因子PvdS具有高度相似性，但其N端延伸约29个氨基酸，在PvdS中不存在。根据其与PvdS依赖性启动子的相似性，在鸟氨酸蛋白基因簇中鉴定了三个预测的OrbS依赖性启动子。这些启动子的铁调节活性显示需要OrbS。发现 orbS 基因的转录受铁调节的σ 70 依赖性启动子的控制。该启动子，而不是OrbS依赖性启动子，被全局调节剂Fur抑制为靶标。我们的结果证明 B产生鸟氨酸。响应铁饥饿而引起的败血症需要转录操纵子，该操纵子依赖于Fur调节的ECFσ因子基因 orbS 。还提出了鸟氨酸生物合成的机制。

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