Department of Applied and Environmental Microbiology, School of Life Sciences, Ludong University, Yantai, China.
J Basic Microbiol. 2018 Sep;58(9):793-805. doi: 10.1002/jobm.201800206. Epub 2018 Jul 11.
In previous studies with Pseudomonas chlororaphis G05, two operons (phzABCDEFG and prnABCD) were confirmed to respectively encode enzymes for biosynthesis of phenazine-1-carboxylic acid and pyrrolnitrin that mainly contributed to suppression of some fungal phytopathogens. Although some regulators were identified to govern their expression, it is not known how two operons coordinately interact. By constructing the phz- or/and prn- deletion mutants, we found that in comparison with the wild-type strain G05, phenazine-1-carboxylic acid production in the mutant G05Δprn obviously decreased in GA broth in the absence of prn, and pyrrolnitrin production in the mutant G05Δphz remarkably declined in the absence of phz. By generating the phzA and prnA transcriptional and translational fusions with a truncated lacZ on shuttle vector or on the chromosome, we found that expression of the phz or prn operon was correspondingly increased in the presence of the prn or phz operon at the post-transcriptional level, not at the transcriptional level. These results indicated that the presence of one operon would promote the expression of the other one operon between the phz and prn. This reciprocal enhancement would keep the strain G05 producing more different antifungal compounds coordinately and living better with growth suppression of other microorganisms.
在先前对假单胞菌 G05 的研究中，确认了两个操纵子（phzABCDEFG 和 prnABCD）分别编码用于合成吩嗪-1-羧酸和吡咯并尼丁的酶，这些酶主要有助于抑制一些真菌植物病原体。尽管已经鉴定了一些调节剂来控制它们的表达，但尚不清楚两个操纵子如何协调相互作用。通过构建 phz 或/和 prn 缺失突变体，我们发现与野生型菌株 G05 相比，在没有 prn 的情况下，突变体 G05Δprn 在 GA 肉汤中产生的吩嗪-1-羧酸明显减少，而在没有 phz 的情况下，突变体 G05Δphz 产生的吡咯并尼丁明显减少。通过在穿梭载体或染色体上用截断的 lacZ 生成 phzA 和 prnA 转录和翻译融合物，我们发现 phz 或 prn 操纵子的表达在转录水平上没有变化，而是在后转录水平上相应增加，在另一个操纵子存在的情况下。这些结果表明，一个操纵子的存在会促进 phz 和 prn 之间另一个操纵子的表达。这种相互增强会使菌株 G05 更协调地产生更多不同的抗真菌化合物，并在其他微生物的生长抑制下更好地生存。
