Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA.
Sci Rep. 2021 Feb 26;11(1):4771. doi: 10.1038/s41598-021-84057-4.
Bacterial-derived polyketide and non-ribosomal peptide natural products are crucial sources of therapeutics and yet little is known about the conditions that favor activation of natural product genes or the regulatory machinery controlling their transcription. Recent findings suggest that the σ system, which includes σ-loaded RNA polymerase and transcriptional activators called enhancer binding proteins (EBPs), might be a common regulator of natural product genes. Here, we explored this idea by analyzing a selected group of putative σ promoters identified in Myxococcus xanthus natural product gene clusters. We show that mutations in putative σ-RNA polymerase binding regions and in putative Nla28 EBP binding sites dramatically reduce in vivo promoter activities in growing and developing cells. We also show in vivo promoter activities are reduced in a nla28 mutant, that Nla28 binds to wild-type fragments of these promoters in vitro, and that in vitro binding is lost when the Nla28 binding sites are mutated. Together, our results indicate that M. xanthus uses σ promoters for transcription of at least some of its natural product genes. Interestingly, the vast majority of experimentally confirmed and putative σ promoters in M. xanthus natural product loci are located within genes and not in intergenic sequences.
细菌衍生的聚酮和非核糖体肽天然产物是治疗的重要来源，但人们对有利于天然产物基因激活的条件或控制其转录的调节机制知之甚少。最近的研究结果表明，σ 系统，包括负载 σ 的 RNA 聚合酶和称为增强子结合蛋白 (EBP) 的转录激活因子，可能是天然产物基因的常见调节剂。在这里，我们通过分析黄色粘球菌天然产物基因簇中鉴定的一组选定的假定 σ 启动子来探讨这个想法。我们表明，假定的 σ-RNA 聚合酶结合区域和假定的 Nla28 EBP 结合位点的突变会显著降低生长和发育细胞中体内启动子的活性。我们还表明，在 nla28 突变体中，体内启动子活性降低，Nla28 在体外与这些启动子的野生型片段结合，并且当 Nla28 结合位点发生突变时，体外结合丢失。总之，我们的结果表明，黄色粘球菌至少使用 σ 启动子转录其一些天然产物基因。有趣的是，黄色粘球菌天然产物基因座中绝大多数经过实验证实和假定的 σ 启动子都位于基因内，而不是基因间序列中。
