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首页> 外文期刊>Journal of bacteriology >The Intracellular Pathogen Rhodococcus equi Produces a Catecholate Siderophore Required for Saprophytic Growth
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The Intracellular Pathogen Rhodococcus equi Produces a Catecholate Siderophore Required for Saprophytic Growth

机译：细胞内病原体红球菌马鞭毛产生腐生性生长所需的儿茶酚铁载体

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Little is known about the iron acquisition systems of the soilborne facultative intracellular pathogen Rhodococcus equi. We previously reported that expression of iupABC, encoding a putative siderophore ABC transporter system, is iron regulated and required for growth at low iron concentrations. Here we show that disruption of iupA leads to the concomitant accumulation of catecholates and a chromophore with absorption maxima at 341 and 528 nm during growth under iron-replete conditions. In contrast, the wild-type strain produces these compounds only in iron-depleted medium. Disruption of iupU and iupS, encoding nonribosomal peptide synthetases, prevented growth of the corresponding R. equi SID1 and SID3 mutants at low iron concentrations. However, only R. equi SID3 did not produce the chromophore produced by the wild-type strain during growth at low iron concentrations. The phenotype of R. equi SID3, but not that of R. equi SID1, could be rescued by coculture with the wild type, allowing growth at low iron concentrations. This strongly suggests that the product of the iupS gene is responsible for the synthesis of a diffusible compound required for growth at low iron concentrations. Transcription of iupU was constitutive, but that of iupS was iron regulated, with an induction of 3 orders of magnitude during growth in iron-depleted compared to iron-replete medium. Neither mutant was attenuated in vivo in a mouse infection model, indicating that the iupU- and iupS-encoded iron acquisition systems are primarily involved in iron uptake during saprophytic life.
机译：对土壤传播兼性细胞内病原体 Rhodococcus equi 的铁捕获系统知之甚少。我们先前曾报道， iupABC 的表达编码铁的ABC转运蛋白假定系统，受铁调节，并且在低铁浓度下生长所需。在这里，我们显示在铁充足的条件下生长期间， iupA 的破坏会导致儿茶酚盐和发色团的同时积累，最大吸收量在341和528 nm。相反，野生型菌株仅在贫铁培养基中产生这些化合物。编码非核糖体肽合成酶的 iupU 和 iupS 的破坏阻止了相应 R的生长。低铁浓度时的equip SID1和SID3突变体。但是，只有 R。 equi SID3在低铁浓度下生长期间不产生野生型菌株产生的发色团。 R的表型。 equi SID3，但不是 R。 equi SID1，可以通过与野生型共培养来挽救，从而可以在低铁浓度下生长。这有力地表明， iupS 基因的产物负责合成低铁浓度下生长所需的可扩散化合物。 iupU 的转录本构，但 iupS 的转录受铁调节，与贫铁培养基相比，贫铁生长过程中诱导了3个数量级。在小鼠感染模型中，这两个突变体均未在体内减弱，这表明 iupU -和 iupS 编码的铁捕获系统主要参与腐生生活中的铁吸收。

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