Department of Chemistry, Brown University, Providence, Rhode Island, USA.
J Bacteriol. 2013 Mar;195(6):1255-66. doi: 10.1128/JB.02079-12. Epub 2013 Jan 11.
The orthologous penR and pntR genes from the pentalenolactone biosynthetic gene clusters of Streptomyces exfoliatus UC5319 and S. arenae TÜ469, respectively, were predicted to encode MarR/SlyA family transcriptional regulators, responsible for regulation of the biosynthesis of the sesquiterpenoid antibiotic pentalenolactone. The intrinsic target DNA sequences and small molecule ligands of purified recombinant PenR and PntR were identified by electrophoretic mobility shift assays. PenR bound to DNA from both the penR-gapN and penM-penH intergenic regions, while PntR bound only the corresponding pntR-gapR intergenic region. The targets of PenR and PntR were shown to be limited to conserved 37-bp DNA segments. Pentalenolactone and two late-stage biosynthetic intermediates, pentalenolactones D and F, act as ligands of both PenR and PntR, resulting in release of these proteins from their target DNA. The production of pentalenolactones was significantly decreased in the penR deletion mutant S. exfoliatus ΔpenR ZD27 but could be restored by complementation with either penR or pntR. Reverse transcription-PCR established that transcription of pentalenolactone biosynthetic and resistance genes decreased, while that of the penR gene itself increased in the penR deletion mutant S. exfoliatus ZD27 compared to the wild-type strain. The PenR protein thus serves as a positive regulator of pentalenolactone biosynthesis and self-resistance while acting as an autorepressor of penR.
来自链霉菌属脱皮亚种 UC5319 和 S. arenae TÜ469 中的 pentalenolactone 生物合成基因簇的同源 penR 和 pntR 基因分别预测编码 MarR/SlyA 家族转录调节剂，负责调节倍半萜类抗生素 pentalenolactone 的生物合成。通过电泳迁移率变动分析鉴定了纯化的重组 PenR 和 PntR 的固有靶 DNA 序列和小分子配体。PenR 结合来自 penR-gapN 和 penM-penH 基因间区的 DNA，而 PntR 仅结合相应的 pntR-gapR 基因间区。PenR 和 PntR 的靶标被证明仅限于保守的 37-bp DNA 片段。pentalenolactone 和两个晚期生物合成中间体 pentalenolactones D 和 F 作为 PenR 和 PntR 的配体，导致这些蛋白质从其靶 DNA 上释放。在链霉菌属脱皮亚种ΔpenR ZD27 的 penR 缺失突变体中，pentalenolactone 的产量显著降低，但通过与 penR 或 pntR 互补可以恢复。反转录-PCR 确定在 penR 缺失突变体 S. exfoliatus ZD27 中，pentalenolactone 生物合成和抗性基因的转录减少，而 penR 基因本身的转录增加，与野生型菌株相比。因此，PenR 蛋白作为 pentalenolactone 生物合成和自我抗性的正调节剂，同时作为 penR 的自身阻遏物。
