The Gac regulon of Pseudomonas fluorescens SBW25
The Gac regulon of Pseudomonas fluorescens SBW25
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DOI：
10.1111/1758-2229.12061
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发表时间：
2013-08-01
影响因子：
3.3
通讯作者：
Raaijmakers, Jos M.
中科院分区：
文献类型：
--
作者：
Cheng, Xu;de Bruijn, Irene;Raaijmakers, Jos M.
荧光假单胞菌SBW25的转录组分析显示，gacS::Tn5突变体中有702个基因受到差异调节，其中分别有300个和402个基因上调和下调。与其他假单胞菌属物种的 Gac 调节子类似，参与运动、生物膜形成、铁载体生物合成和氧化应激的基因在 SBW25 的 gacS 突变体中受到差异调节。我们的分析还首次揭示，在 gacS 突变体中，19 个根际诱导基因以及涉及 II 型分泌、（外）多糖和果胶酸裂合酶生物合成、抽搐运动和孤儿非核糖体肽合成酶（NRPS）的基因的转录受到显着影响。此外，gacS突变体对卵菌、真菌和细菌病原体生长的抑制作用显着强于野生型SBW25。由于 RP-HPLC 分析没有揭示任何潜在的候选代谢物，因此我们将重点放在 Gac 调节的孤儿 NRPS 基因簇上，该基因簇预计编码八个氨基酸的鸟角蛋白样肽。定点诱变表明，编码的肽不参与 gacS 突变体增强的抗菌活性，但可能起到铁载体的作用。总的来说，这项全基因组分析表明，GacS/A 双组分调控系统中的突变导致 SBW25 发生重大转录变化，并通过未知的机制显着增强其抗菌活性。
Transcriptome analysis of Pseudomonas fluorescensSBW25 showed that 702 genes were differentially regulated in a gacS::Tn5 mutant, with 300 and 402 genes up- and downregulated respectively. Similar to the Gac regulon of other Pseudomonas species, genes involved in motility, biofilm formation, siderophore biosynthesis and oxidative stress were differentially regulated in the gacS mutant of SBW25. Our analysis also revealed, for the first time, that transcription of 19 rhizosphere-induced genes and of genes involved in type II secretion, (exo)polysaccharide and pectate lyase biosynthesis, twitching motility and an orphan non-ribosomal peptide synthetase (NRPS) were significantly affected in the gacS mutant. Furthermore, the gacS mutant inhibited growth of oomycete, fungal and bacterial pathogens significantly more than wild type SBW25. Since RP-HPLC analysis did not reveal any potential candidate metabolites, we focused on the Gac-regulated orphan NRPS gene cluster that was predicted to encode an eight-amino-acid ornicorrugatin-like peptide. Site-directed mutagenesis indicated that the encoded peptide is not involved in the enhanced antimicrobial activity of the gacS mutant but may function as a siderophore. Collectively, this genome-wide analysis revealed that a mutation in the GacS/A two-component regulatory system causes major transcriptional changes in SBW25 and significantly enhances its antimicrobial activities by yet unknown mechanisms.