LysR-Type Transcriptional Regulator MetR Controls Prodigiosin Production, Methionine Biosynthesis, Cell Motility, H2O2 Tolerance, Heat Tolerance, and Exopolysaccharide Synthesis in Serratia marcescens
LysR-Type Transcriptional Regulator MetR Controls Prodigiosin Production, Methionine Biosynthesis, Cell Motility, H2O2 Tolerance, Heat Tolerance, and Exopolysaccharide Synthesis in Serratia marcescens
复制标题
LysR 型转录调节因子 MetR 控制粘质沙雷氏菌中灵菌红的产生、蛋氨酸生物合成、细胞运动、H2O2 耐受性、耐热性和胞外多糖合成
DOI：
10.1128/aem.02241-19
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发表时间：
2020-02-01
影响因子：
4.4
通讯作者：
Rao, Zhiming
中科院分区：
文献类型：
--
作者：
Pan, Xuewei;Sun, Changhao;Rao, Zhiming
粘质沙雷氏菌是一种革兰氏阴性细菌，广泛存在于生态位中，可以产生多种次级代谢产物，包括灵菌红、阿硫霉素和沙雷莫利特。其中，灵菌红显示出作为免疫抑制剂、抗菌剂和抗癌剂的多种功能。然而，粘质链球菌中灵菌红素合成背后的调控机制尚不完全清楚。在这里，我们采用转座子突变体文库来鉴定与灵菌红素合成相关的基因，发现编码LysR型调节因子MetR的BVG90_22495基因对灵菌红素合成负调节。研究了metR突变体高产灵菌红素的分子机制。此外，我们还提供了证据支持 MetR 在调节粘质链球菌中的甲硫氨酸生物合成、细胞运动、耐热性、H2O2 耐受性和胞外多糖合成中的新作用。总的来说，这项工作为灵菌红素合成的调节机制提供了新的见解，并揭示了高度保守的 MetR 蛋白在调节灵菌红素合成、耐热性、胞外多糖 (EPS) 合成和生物膜形成中的新作用。摘要 灵菌红素是粘质沙雷氏菌产生的次级代谢产物，因其免疫抑制、抗菌和抗癌特性而引起人们的关注。然而，关于粘质链球菌中灵菌红素生物合成背后的调节机制的信息仍然有限。在这项工作中，从 Tn5G 转座子插入突变体的集合中选择了 BVG90_22495 基因破坏的灵菌红高产菌株（ZK66）。使用实时定量 PCR (RT-qPCR) 分析、β-半乳糖苷酶测定、转录组学分析和电泳迁移率变动测定 (EMSA)，发现 BVG90_22495 基因编码的 LysR 型调节因子 MetR 影响灵菌红素合成，这与 MetR 直接结合到灵菌红素启动子区域相关。 灵菌红合成正调节剂 PigP，因此负调节灵菌红相关猪操纵子的表达。更多分析表明，MetR 调节粘质链球菌中其他一些重要的细胞过程，包括甲硫氨酸生物合成、细胞运动、H2O2 耐受性、耐热性、胞外多糖合成和生物膜形成。尽管 MetR 蛋白在许多细菌中高度保守，但我们在此报道了 LysR 型调节剂 MetR 在负向调节灵菌红素合成和正向调节耐热性、胞外多糖合成和生物膜形成方面表现出新的作用。重要性 粘质沙雷氏菌是一种革兰氏阴性细菌，广泛存在于生态位中，可以产生多种次级代谢产物，包括灵菌红、阿硫霉素和沙雷莫利特。其中，灵菌红显示出作为免疫抑制剂、抗菌剂和抗癌剂的多种功能。然而，粘质链球菌中灵菌红素合成背后的调控机制尚不完全清楚。在这里，我们采用转座子突变体文库来鉴定与灵菌红素合成相关的基因，发现编码LysR型调节因子MetR的BVG90_22495基因对灵菌红素合成负调节。研究了metR突变体高产灵菌红素的分子机制。此外，我们还提供了证据支持 MetR 在调节粘质链球菌中的甲硫氨酸生物合成、细胞运动、耐热性、H2O2 耐受性和胞外多糖合成中的新作用。总的来说，这项工作为灵菌红素合成的调节机制提供了新的见解，并揭示了高度保守的 MetR 蛋白在调节灵菌红素合成、耐热性、胞外多糖 (EPS) 合成和生物膜形成中的新作用。
Serratia marcescens, a Gram-negative bacterium, is found in a wide range of ecological niches and can produce several secondary metabolites, including prodigiosin, althiomycin, and serratamolide. Among them, prodigiosin shows diverse functions as an immunosuppressant, antimicrobial, and anticancer agent. However, the regulatory mechanisms behind prodigiosin synthesis in S. marcescens are not completely understood. Here, we adapted a transposon mutant library to identify the genes related to prodigiosin synthesis, and the BVG90_22495 gene encoding the LysR-type regulator MetR was found to negatively regulate prodigiosin synthesis. The molecular mechanism of the metR mutant hyperproducing prodigiosin was investigated. Additionally, we provided evidence supporting new roles for MetR in regulating methionine biosynthesis, cell motility, heat tolerance, H2O2 tolerance, and exopolysaccharide synthesis in S. marcescens. Collectively, this work provides novel insight into regulatory mechanisms of prodigiosin synthesis and uncovers novel roles for the highly conserved MetR protein in regulating prodigiosin synthesis, heat tolerance, exopolysaccharide (EPS) synthesis, and biofilm formation. ABSTRACT Prodigiosin, a secondary metabolite produced by Serratia marcescens, has attracted attention due to its immunosuppressive, antimicrobial, and anticancer properties. However, information on the regulatory mechanism behind prodigiosin biosynthesis in S. marcescens remains limited. In this work, a prodigiosin-hyperproducing strain with the BVG90_22495 gene disrupted (ZK66) was selected from a collection of Tn5G transposon insertion mutants. Using real-time quantitative PCR (RT-qPCR) analysis, β-galactosidase assays, transcriptomics analysis, and electrophoretic mobility shift assays (EMSAs), the LysR-type regulator MetR encoded by the BVG90_22495 gene was found to affect prodigiosin synthesis, and this correlated with MetR directly binding to the promoter region of the prodigiosin-synthesis positive regulator PigP and hence negatively regulated the expression of the prodigiosin-associated pig operon. More analyses revealed that MetR regulated some other important cellular processes, including methionine biosynthesis, cell motility, H2O2 tolerance, heat tolerance, exopolysaccharide synthesis, and biofilm formation in S. marcescens. Although MetR protein is highly conserved in many bacteria, we report here on the LysR-type regulator MetR exhibiting novel roles in negatively regulating prodigiosin synthesis and positively regulating heat tolerance, exopolysaccharide synthesis, and biofilm formation. IMPORTANCE Serratia marcescens, a Gram-negative bacterium, is found in a wide range of ecological niches and can produce several secondary metabolites, including prodigiosin, althiomycin, and serratamolide. Among them, prodigiosin shows diverse functions as an immunosuppressant, antimicrobial, and anticancer agent. However, the regulatory mechanisms behind prodigiosin synthesis in S. marcescens are not completely understood. Here, we adapted a transposon mutant library to identify the genes related to prodigiosin synthesis, and the BVG90_22495 gene encoding the LysR-type regulator MetR was found to negatively regulate prodigiosin synthesis. The molecular mechanism of the metR mutant hyperproducing prodigiosin was investigated. Additionally, we provided evidence supporting new roles for MetR in regulating methionine biosynthesis, cell motility, heat tolerance, H2O2 tolerance, and exopolysaccharide synthesis in S. marcescens. Collectively, this work provides novel insight into regulatory mechanisms of prodigiosin synthesis and uncovers novel roles for the highly conserved MetR protein in regulating prodigiosin synthesis, heat tolerance, exopolysaccharide (EPS) synthesis, and biofilm formation.