Abstract：
BACKGROUND: Quorum sensing inhibitors (QSIs) are an emerging control tool that inhibits the quorum sensing (QS) system of pathogenic bacteria. We aimed to screen for potential QSIs in the metabolites of Trichoderma and to explore their inhibitory mechanisms.
RESULTS: We screened a strain of Trichoderma asperellum LN004, which demonstrated the ability to inhibit the color development of Chromobacterium subtsugae CV026, primarily attributed to the presence of emodin as its key QSI component. The quantitative polymerase chain reaction with reverse transcription results showed that after emodin treatment of Pectobacterium carotovorum subsp. carotovorum (Pcc), plant cell wall degrading enzyme-related synthetic genes were significantly downregulated, and the exogenous enzyme synthesis gene negative regulator (rsmA) was upregulated 3.5-fold. Docking simulations indicated that emodin could be a potential ligand for ExpI and ExpR proteins because it exhibited stronger competition than the natural ligands in Pcc. In addition, western blotting showed that emodin attenuated the degradation of n-acylhomoserine lactone on the ExpR protein and protected it. Different concentrations of emodin reduced the activity of pectinase, cellulase, and protease in Pcc by 20.81%-72.21%, 8.38%-52.73%, and 3.57%-47.50%. Lesion size in Chinese cabbages, carrots and cherry tomatoes following Pcc infestation was reduced by 10.02%-68.57%, 40.17%-88.56% and 11.36%-86.17%.
CONCLUSIONS: Emodin from T. asperellum LN004 as a QSI can compete to bind both ExpI and ExpR proteins, interfering with the QS of Pcc and reducing the production of virulence factors. The first molecular mechanism reveals the ability of emodin as a QSI to competitively inhibit two QS proteins simultaneously. © 2023 Society of Chemical Industry.
RESULTS: We screened a strain of Trichoderma asperellum LN004, which demonstrated the ability to inhibit the color development of Chromobacterium subtsugae CV026, primarily attributed to the presence of emodin as its key QSI component. The quantitative polymerase chain reaction with reverse transcription results showed that after emodin treatment of Pectobacterium carotovorum subsp. carotovorum (Pcc), plant cell wall degrading enzyme-related synthetic genes were significantly downregulated, and the exogenous enzyme synthesis gene negative regulator (rsmA) was upregulated 3.5-fold. Docking simulations indicated that emodin could be a potential ligand for ExpI and ExpR proteins because it exhibited stronger competition than the natural ligands in Pcc. In addition, western blotting showed that emodin attenuated the degradation of n-acylhomoserine lactone on the ExpR protein and protected it. Different concentrations of emodin reduced the activity of pectinase, cellulase, and protease in Pcc by 20.81%-72.21%, 8.38%-52.73%, and 3.57%-47.50%. Lesion size in Chinese cabbages, carrots and cherry tomatoes following Pcc infestation was reduced by 10.02%-68.57%, 40.17%-88.56% and 11.36%-86.17%.
CONCLUSIONS: Emodin from T. asperellum LN004 as a QSI can compete to bind both ExpI and ExpR proteins, interfering with the QS of Pcc and reducing the production of virulence factors. The first molecular mechanism reveals the ability of emodin as a QSI to competitively inhibit two QS proteins simultaneously. © 2023 Society of Chemical Industry.
摘要：
背景：群体感应抑制剂（QSI）是一种新兴的控制工具，可以抑制病原菌的群体感应（QS）系统。我们旨在筛选木霉属代谢物中潜在的QSI，并探讨其抑制机制。
结果：我们筛选了一株木霉菌LN004菌株，该菌株显示出抑制sb下色杆菌CV026颜色发育的能力，主要归因于大黄素作为其关键QSI成分的存在。.qRT-PCR成果显示，大黄素处置后能对类烟杆菌亚种。Carotovorum(Pcc),PCWDEs相关合成基因显著下调，外源酶合成基因负调节因子(rsmA)上调3.5倍。对接模拟表明大黄素可能是ExpI和ExpR蛋白的潜在配体，因为它比Pcc中的天然配体表现出更强的竞争。此外,Westernblot结果显示,大黄素能抑制正酰基高丝氨酸(AHL)内酯对ExpR蛋白的降解并对其起到保护作用。不同浓度的大黄素降低果胶酶的活性，纤维素酶,Pcc中的蛋白酶减少了20.81-72.21%，8.38-52.73%，和3.57-47.50%，卷心菜的病变大小，受Pcc感染的胡萝卜和樱桃番茄减少了10.02-68.57％，40.17-88.56%和11.36-86.17%。
结论：来自木霉LN004的大黄素作为QSI可以竞争结合ExpI和ExpR蛋白，干扰Pcc的QS，减少毒力因子的产生。第一个分子机制揭示了大黄素作为QSI同时竞争性抑制两种QS蛋白的能力。本文受版权保护。保留所有权利。
结果：我们筛选了一株木霉菌LN004菌株，该菌株显示出抑制sb下色杆菌CV026颜色发育的能力，主要归因于大黄素作为其关键QSI成分的存在。.qRT-PCR成果显示，大黄素处置后能对类烟杆菌亚种。Carotovorum(Pcc),PCWDEs相关合成基因显著下调，外源酶合成基因负调节因子(rsmA)上调3.5倍。对接模拟表明大黄素可能是ExpI和ExpR蛋白的潜在配体，因为它比Pcc中的天然配体表现出更强的竞争。此外,Westernblot结果显示,大黄素能抑制正酰基高丝氨酸(AHL)内酯对ExpR蛋白的降解并对其起到保护作用。不同浓度的大黄素降低果胶酶的活性，纤维素酶,Pcc中的蛋白酶减少了20.81-72.21%，8.38-52.73%，和3.57-47.50%，卷心菜的病变大小，受Pcc感染的胡萝卜和樱桃番茄减少了10.02-68.57％，40.17-88.56%和11.36-86.17%。
结论：来自木霉LN004的大黄素作为QSI可以竞争结合ExpI和ExpR蛋白，干扰Pcc的QS，减少毒力因子的产生。第一个分子机制揭示了大黄素作为QSI同时竞争性抑制两种QS蛋白的能力。本文受版权保护。保留所有权利。
