Post-translation regulation of antibiotic production in Streptomyces: the loaded gun hypothesis.

链霉菌抗生素生产的翻译后调控：装弹枪假说。

• 批准号: BB/W000628/1
• 负责人: Matthew Hutchings
• 金额: $ 70.67万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FW000628%2F1
• 关键词: Post; translation; regulation; antibiotic; production

Around three quarters of the antibiotics we use in human medicine are derived from the natural products of soil bacteria and fungi. We call these natural products specialised metabolites because they have a specialised function, which is usually to kill other bacteria and fungi in the highly competitive soil environment. These molecules can also be toxic to worms, insects and even plants and many have been used in medicine to treat parasite infections and as herbicides or pesticides in agriculture. The biggest producers of specialised metabolites are Streptomyces bacteria which make around 50% of all known antibiotics. These bacteria are incredibly important to humans but we have relatively little understanding of how they control the production of their specialised metabolites. This is important because they only make around 10% of their specialised metabolites when we grow them in the laboratory. We know this from sequencing all the DNA in their cells which shows they have the instructions and capacity to make many more. If we can understand how they control their production we should be able to engineer strains to switch on production of all the specialised metabolites in all of the >600 known Streptomyces species and discover many new and potentially useful natural products, including antibiotics. As part of our efforts to identify the master regulators of antibiotic production, we characterised a DNA binding protein called MtrA which is found in all Streptomyces species. MtrA controls antibiotic production in all the Streptomyces strains that have been tested so far and is part of a signal transduction pathway called a two-component system. These signalling systems are common in bacteria. MtrA is a response regulator, and these proteins are typically transcription factors which control gene expression by binding to promoter DNA. The DNA binding activity of MtrA is controlled by MtrB, a sensor kinase which spans the cell membrane and senses a signal outside the cell and then phosphorylates and activates MtrA inside the cell. MtrA binds to around 80% of the predicted biosynthetic gene clusters for specialised metabolites in Streptomyces coelicolor and S. venezuelae. MtrA also binds to other transcription factors which is unusual in bacteria and to enzymes involved in making specialised metabolites which, to our knowledge, has never been described before for any other bacterial transcription factor. In this proposal we will use S. venezuelae as a model to characterise the regulation of antibiotic production by MtrA since it controls chloramphenicol production by binding to the transporter genes and to the enzyme CmlS, which catalyses the final step in the biosynthetic pathway. It appears that antibiotic biosynthesis does not occur from scratch. Instead we hypothesise that it is like a loaded gun, the precursor is made but the final step is blocked by MtrA. When MtrA is switched off it is like pulling the trigger - the final step occurs, and the active antibiotic is made, the transport genes are expressed and the active compound is exported from the cell. In this project we will test this "loaded gun" hypothesis and the results will likely change the way we think about bacterial transcription factors and the regulation of antibiotic biosynthesis.MtrA also binds to a closely related response regulator called Vnz13500 which is conserved in Streptomyces species and probably also activated by MtrB suggesting its functions are complex in S. venezuelae. To test whether these functions are conserved in other streptomycetes we will use the distantly related S. coelicolor which is also experimentally tractable. Published data from our and other groups suggests S. coelicolor MtrAB and SCO3008 (its Vnz13500 homologue) are involved in controlling production of its antibiotic undecylprodigiosin and we will test if it does this at both the transcriptional and post translational levels.

我们在人类医学中使用的抗生素中，大约四分之三源自土壤细菌和真菌的天然产物。我们将这些天然产物称为特殊代谢物，因为它们具有特殊的功能，通常是在竞争激烈的土壤环境中杀死其他细菌和真菌。这些分子还可能对蠕虫、昆虫甚至植物有毒，许多分子已用于治疗寄生虫感染的药物以及农业中的除草剂或杀虫剂。专门代谢物的最大生产者是链霉菌属细菌，它生产的抗生素约占所有已知抗生素的 50%。这些细菌对人类非常重要，但我们对它们如何控制其特殊代谢物的产生知之甚少。这很重要，因为当我们在实验室培养它们时，它们只能产生大约 10% 的专门代谢物。我们通过对它们细胞中的所有 DNA 进行测序得知这一点，这表明它们拥有制造更多DNA的指令和能力。如果我们能够了解它们如何控制其生产，我们应该能够设计菌株来启动所有超过 600 种已知链霉菌物种中所有特殊代谢物的生产，并发现许多新的和潜在有用的天然产物，包括抗生素。作为我们努力确定抗生素生产主要调节因子的一部分，我们鉴定了一种称为 MtrA 的 DNA 结合蛋白，它存在于所有链霉菌属物种中。 MtrA 控制迄今为止已测试的所有链霉菌菌株中的抗生素生产，并且是称为双组分系统的信号转导途径的一部分。这些信号系统在细菌中很常见。 MtrA 是一种反应调节因子，这些蛋白质通常是转录因子，通过与启动子 DNA 结合来控制基因表达。 MtrA 的 DNA 结合活性由 MtrB 控制，MtrB 是一种传感器激酶，它跨越细胞膜并感知细胞外的信号，然后磷酸化并激活细胞内的 MtrA。 MtrA 与天蓝色链霉菌和委内瑞拉链霉菌中约 80% 的特定代谢物的预测生物合成基因簇结合。 MtrA 还与其他转录因子（这在细菌中不常见）结合，并与参与制造特殊代谢物的酶结合，据我们所知，以前从未对任何其他细菌转录因子进行过描述。在本提案中，我们将使用委内瑞拉链球菌作为模型来表征 MtrA 对抗生素生产的调节，因为它通过与转运蛋白基因和酶 CmlS 结合来控制氯霉素的生产，CmlS 催化生物合成途径的最后一步。看来抗生素的生物合成并不是从头开始的。相反，我们假设它就像一把上了膛的枪，前体已经制造出来，但最后一步被 MtrA 阻止了。当 MtrA 关闭时，就像扣动扳机一样——最后一步发生，活性抗生素被制造出来，转运基因被表达，活性化合物从细胞中输出。在这个项目中，我们将测试这种“上膛的枪”假设，结果可能会改变我们对细菌转录因子和抗生素生物合成调节的思考方式。MtrA 还与一种密切相关的反应调节因子 Vnz13500 结合，该调节因子在链霉菌属物种中保守并且可能也被 MtrB 激活，表明其在委内瑞拉链球菌中的功能很复杂。为了测试这些功能在其他链霉菌中是否保守，我们将使用远缘的天蓝色链霉菌，它在实验上也易于处理。我们和其他小组公布的数据表明，S. coelicolor MtrAB 和 SCO3008（其 Vnz13500 同源物）参与控制其抗生素十一烷基灵菌红素的产生，我们将测试它是否在转录和翻译后水平上发挥作用。

项目成果

Evidence of a role for CutRS and actinorhodin in the secretion stress response in Streptomyces coelicolor M145.

• DOI: 10.1099/mic.0.001358
• 发表时间: 2023-07
• 期刊: MICROBIOLOGY-SGM
• 影响因子: 2.8
• 作者: McLean, Thomas C.;Beaton, Ainsley D. M.;Martins, Carlo;Saalbach, Gerhard;Chandra, Govind;Wilkinson, Barrie;Hutchings, Matthew I.
• 通讯作者: Hutchings, Matthew I.