State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Appl Microbiol Biotechnol. 2018 Nov;102(22):9719-9730. doi: 10.1007/s00253-018-9282-0. Epub 2018 Aug 21.
The rhizobacterium Pseudomonas protegens H78 biosynthesizes a number of antibiotic compounds, including pyoluteorin, 2,4-diacetylphloroglucinol, and pyrrolnitrin. Here, we investigated the global regulatory function of the nitrogen metabolism-related sigma factor RpoN in P. protegens H78 through RNA-seq and phenotypic analysis. During the mid- to late-log growth phase, transcriptomic profiling revealed that 562 genes were significantly upregulated, and 502 genes were downregulated by at least twofold at the RNA level in the rpoN deletion mutant in comparison with the wild-type strain H78. With respect to antibiotics, Plt biosynthesis and the expression of its operon were positively regulated, while Prn biosynthesis and the expression of its operon were negatively regulated by RpoN. RpoN is responsible for the global activation of operons involved in flagellar biogenesis and assembly, biofilm formation, and bacterial mobility. In contrast, RpoN was shown to negatively control a number of secretion system operons including one type VI secretion system operon (H1-T6SS), two pilus biogenesis operons (Flp/Tad-T4b pili and Csu-T1 pili), and one polysaccharide biosynthetic operon (psl). In addition, two operons that are involved in mannitol and inositol utilization are under the positive regulation of RpoN. Consistent with this result, the ability of H78 to utilize mannitol or inositol as a sole carbon source is positively influenced by RpoN. Taken together, the RpoN-mediated global regulation is mainly involved in flagellar biogenesis and assembly, bacterial mobility, biofilm formation, antibiotic biosynthesis, secretion systems, and carbon utilization in P. protegens H78.
根际细菌恶臭假单胞菌 H78 生物合成多种抗生素化合物，包括吡咯并喹啉醌、2,4-二乙酰基间苯二酚和吡咯菌素。在这里，我们通过 RNA-seq 和表型分析研究了氮代谢相关 sigma 因子 RpoN 在恶臭假单胞菌 H78 中的全局调控功能。在中到对数生长后期，转录组谱分析显示，与野生型菌株 H78 相比，rpoN 缺失突变体中 562 个基因的转录水平显著上调，502 个基因的转录水平至少下调了两倍。就抗生素而言，plt 生物合成及其操纵子的表达受到正调控，而 prn 生物合成及其操纵子的表达受到 RpoN 的负调控。RpoN 负责参与鞭毛生物发生和组装、生物膜形成和细菌运动的操纵子的全局激活。相反，RpoN 被证明负调控许多分泌系统操纵子，包括一个类型 VI 分泌系统操纵子（H1-T6SS）、两个菌毛生物发生操纵子（Flp/Tad-T4b 菌毛和 Csu-T1 菌毛）和一个多糖生物合成操纵子（psl）。此外，两个涉及甘露醇和肌醇利用的操纵子受 RpoN 的正调控。与这一结果一致，H78 利用甘露醇或肌醇作为唯一碳源的能力受到 RpoN 的正向影响。总之，RpoN 介导的全局调控主要涉及鞭毛生物发生和组装、细菌运动、生物膜形成、抗生素生物合成、分泌系统和恶臭假单胞菌 H78 中的碳利用。
