多种因素的遗传控制和镁水平控制着一种具有不寻常细胞密度依赖性的抗生素的产生。
Multifactorial genetic control and magnesium levels govern the production of a antibiotic with unusual cell density dependence.
机构信息
Institute of Infectious Disease Research and Department of Biology, McMaster University, Hamilton, Ontario, Canada.
出版信息
mSystems. 2024 Apr 16;9(4):e0136823. doi: 10.1128/msystems.01368-23. Epub 2024 Mar 11.
bacteria are renowned both for their antibiotic production capabilities and for their cryptic metabolic potential. Their metabolic repertoire is subject to stringent genetic control, with many of the associated biosynthetic gene clusters being repressed by the conserved nucleoid-associated protein Lsr2. In an effort to stimulate new antibiotic production in wild isolates, we leveraged the activity of an Lsr2 knockdown construct and successfully enhanced antibiotic production in the wild isolate WAC07094. We determined that this new activity stemmed from increased levels of the angucycline-like family member saquayamycin. Saquayamycin has both antibiotic and anti-cancer activities, and intriguingly, beyond Lsr2-mediated repression, we found saquayamycin production was also suppressed at high density on solid or in liquid growth media; its levels were greatest in low-density cultures. This density-dependent control was exerted at the level of the cluster-situated regulatory gene and was mediated in part through the activity of the PhoRP two-component regulatory system, where deleting led to both constitutive antibiotic production and expression. This suggests that PhoP functions to repress the expression of at high cell density. We further discovered that magnesium supplementation could alleviate this density dependence, although its action was independent of PhoP. Finally, we revealed that the nitrogen-responsive regulators GlnR and AfsQ1 could relieve the repression exerted by Lsr2 and PhoP. Intriguingly, we found that this low density-dependent production of saquayamycin was not unique to WAC07094; saquayamycin production by another wild isolate also exhibited low-density activation, suggesting that this spatial control may serve an important ecological function in their native environments.IMPORTANCE specialized metabolic gene clusters are subject to complex regulation, and their products are frequently not observed under standard laboratory growth conditions. For the wild isolate WAC07094, production of the angucycline-family compound saquayamycin is subject to a unique constellation of control factors. Notably, it is produced primarily at low cell density, in contrast to the high cell density production typical of most antibiotics. This unusual density dependence is conserved in other saquayamycin producers and is driven by the pathway-specific regulator SqnR, whose expression is influenced by both nutritional and genetic elements. Collectively, this work provides new insights into an intricate regulatory system governing antibiotic production and indicates there may be benefits to including low-density cultures in antibiotic screening platforms.
细菌以其抗生素生产能力和隐藏的代谢潜力而闻名。它们的代谢谱受到严格的遗传控制,许多相关的生物合成基因簇被保守的核相关蛋白 Lsr2 抑制。为了刺激野生分离株产生新的抗生素,我们利用 Lsr2 敲低构建体的活性,成功地增强了野生分离株 WAC07094 的抗生素产生。我们确定这种新的活性源于 angucycline 样家族成员 saquayamycin 水平的增加。Saquayamycin 具有抗生素和抗癌活性,有趣的是,除了 Lsr2 介导的抑制作用外,我们还发现 saquayamycin 的产生在固体或液体生长培养基中的高密度下也受到抑制;其水平在低密度培养物中最高。这种密度依赖性控制是在位于簇中的调节基因 的水平上施加的,部分是通过 PhoRP 双组分调节系统的活性介导的,其中删除 导致组成型抗生素产生和 表达。这表明 PhoP 功能是在高细胞密度时抑制 的表达。我们进一步发现,镁补充可以减轻这种密度依赖性,尽管其作用独立于 PhoP。最后,我们发现氮响应调节剂 GlnR 和 AfsQ1 可以缓解 Lsr2 和 PhoP 施加的抑制作用。有趣的是,我们发现 WAC07094 并不是唯一表现出 saquayamycin 低密度依赖性产生的野生分离株;另一个野生分离株也表现出 saquayamycin 的低浓度激活,这表明这种空间控制可能在其天然环境中发挥重要的生态功能。
重要性
专门的代谢基因簇受到复杂的调节,它们的产物通常在标准实验室生长条件下观察不到。对于野生 分离株 WAC07094,angucycline 家族化合物 saquayamycin 的产生受到一组独特的控制因素的影响。值得注意的是,与大多数抗生素典型的高细胞密度生产相反,它主要在低细胞密度下产生。这种不寻常的密度依赖性在其他 saquayamycin 产生菌中是保守的,由途径特异性调节剂 SqnR 驱动,其表达受营养和遗传因素的影响。总的来说,这项工作为控制抗生素产生的复杂调节系统提供了新的见解,并表明在抗生素筛选平台中包括低密度培养可能会有好处。