Pyoverdines Are Essential for the Antibacterial Activity of Pseudomonas chlororaphis YL-1 under Low-Iron Conditions
Pyoverdines Are Essential for the Antibacterial Activity of Pseudomonas chlororaphis YL-1 under Low-Iron Conditions
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吡维丁对于低铁条件下绿针假单胞菌 YL-1 的抗菌活性至关重要
DOI：
10.1128/aem.02840-20
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发表时间：
2021-04-01
影响因子：
4.4
通讯作者：
Lu, Shi-En
中科院分区：
文献类型：
--
作者：
Liu, Youzhou;Dai, Chen;Lu, Shi-En
结果表明，在低铁条件下，PVDs对于菌株YL-1对革兰氏阳性菌和革兰氏阴性菌的广谱抗菌活性至关重要。我们的研究结果还强调了外源性铁对PVD产生的影响以及这种细菌产物在细菌相互作用中的重要性。PVDs作为生防菌，除参与铁竞争外，还可直接抑制被测细菌的增殖。绿针假单胞菌YL-1对植物病原菌具有广泛的抗菌活性，其基因组中含有绿脓菌荧光素（PVD）生物合成基因簇。铜绿假单胞菌PAO 1中的替代σ因子PvdS在响应铁饥饿中充当关键调节剂。PVD骨架的组装开始于肽合成酶PvdL。PvdF催化I-OH-Orn的还原以产生I-N5-羟基鸟氨酸。在这里，我们描述了YL-1中PVD产生的表征及其与其PVD缺陷ΔpvdS、ΔpvdF和ΔpvdL突变体的抗菌活性的比较，这些突变体是使用基于sacB的位点特异性诱变策略获得的。使用体外方法，我们研究了低铁条件下的外源铁和铁螯合剂在铁充足的条件下对PVD生产，抗菌活性和PVD转录因子基因pvdS在YL-1中的相对表达的影响。结果表明，菌株YL-1、ΔpvdF突变株和ΔpvdS（pUCP 26-pvdS）互补株在低铁条件下能产生明显的PVD，并对革兰氏阴性菌和革兰氏阳性菌表现出广泛的体外抑菌作用，且随着铁浓度的增加，其PVD产生量和抑菌活性降低。经液相色谱-串联质谱（LC-MS/MS）分析，菌株YL-1在低铁条件下产生的抗菌化合物为PVDs。此外，在体外观察到的抗菌活性与菌株YL-1对由黄单胞菌引起的水稻白叶枯病（BLB）的体内防治效果相关。米。总的来说，PVDs负责菌株YL-1在天然和诱导的低铁条件下的抗菌活性。结果表明，PVDs是菌株YL-1在低铁条件下对革兰氏阳性菌和革兰氏阴性菌的广谱抗菌活性所必需的。我们的研究结果还强调了外源性铁对PVD产生的影响以及这种细菌产物在细菌相互作用中的重要性。PVDs作为生防菌，除参与铁竞争外，还可直接抑制被测细菌的增殖。
The results demonstrated that PVDs are essential for the broad-spectrum antibacterial activities of strain YL-1 against both Gram-positive and Gram-negative bacteria under low-iron conditions. Our findings also highlight the effect of exogenous iron on the production of PVD and the importance of this bacterial product in bacterial interactions. As a biocontrol agent, PVDs can directly inhibit the proliferation of the tested bacteria in addition to participating in iron competition. ABSTRACT Pseudomonas chlororaphis YL-1 has extensive antimicrobial activities against phytopathogens, and its genome harbors a pyoverdine (PVD) biosynthesis gene cluster. The alternative sigma factor PvdS in Pseudomonas aeruginosa PAO1 acts as a critical regulator in response to iron starvation. The assembly of the PVD backbone starts with peptide synthetase enzyme PvdL. PvdF catalyzes formylation of l-OH-Orn to produce l-N5-hydroxyornithine. Here, we describe the characterization of PVD production in YL-1 and its antimicrobial activity in comparison with that of its PVD-deficient ΔpvdS, ΔpvdF, and ΔpvdL mutants, which were obtained using a sacB-based site-specific mutagenesis strategy. Using in vitro methods, we examined the effect of exogenous iron under low-iron conditions and an iron-chelating agent under iron-sufficient conditions on PVD production, antibacterial activity, and the relative expression of the PVD transcription factor gene pvdS in YL-1. We found that strain YL-1, the ΔpvdF mutant, and the ΔpvdS(pUCP26-pvdS) complemented strain produced visible PVDs and demonstrated a wide range of inhibitory effects against Gram-negative and Gram-positive bacteria in vitro under low-iron conditions and that with the increase of iron, its PVD production and antibacterial activity were reduced. The antibacterial compounds produced by strain YL-1 under low-iron conditions were PVDs based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Moreover, the antibacterial activity observed in vitro was correlated with in vivo control efficacies of strain YL-1 against rice bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae. Collectively, PVDs are responsible for the antibacterial activities of strain YL-1 under both natural and induced low-iron conditions. IMPORTANCE The results demonstrated that PVDs are essential for the broad-spectrum antibacterial activities of strain YL-1 against both Gram-positive and Gram-negative bacteria under low-iron conditions. Our findings also highlight the effect of exogenous iron on the production of PVD and the importance of this bacterial product in bacterial interactions. As a biocontrol agent, PVDs can directly inhibit the proliferation of the tested bacteria in addition to participating in iron competition.