查找使用阿拉丁产品的科研文献

Promoted sulfamethoxazole extracellular biodegradation in Citrobacter freundii JH@Pd by launching AcrB efflux pump

Jian Gao,Jingyu Wu,Yuancai Chen

This study found that bio-Pd 0 nanoparticles could launch proton motive force (PMF)-mediated antibiotics efflux pump (AEP) to confer the detoxification capability on Citrobacter freundii , as evidenced by the highest sulfamethoxazole (SMX) specific degradation rate (81.7 μg L −1 mg −1 protein d −1 ) at high PMF (pH 6). The batch experiment and RT-qPCR results indicated that bio-Pd 0 activated the AcrB efflux pump through upregulating the AEP transcriptional regulation factor ramA (2.7–3.1 times), which benefited the intra/extracellular respiration and ATP production/utilization. Path analysis revealed that the prosperity of metabolic activity and extracellular electron output capacity enabled SMX biodegradation, mainly through the electron redistribution and energy optimization with the formate dehydrogenase/hydrogenase based Short-chain (FDH/Hase-S-chain). The upregulation of hypE (2.7–8.6 times) and atpD (1.9–2.3 times) genes encoding the Hase respiratory chain and the F-type ATP synthase, respectively, further supports this mechanism. These novel findings provided a new strategy to improve the biodegradation efficiency of antibiotics wastewater.

Analysis of Regulatory Mechanism of AcrB and CpxR on Colistin Susceptibility Based on Transcriptome and Metabolome of Salmonella Typhimurium

Ya-Jun Zhai,Pei-Yi Liu,Xing-Wei Luo,Jun Liang,Ya-Wei Sun,Xiao-Die Cui,Dan-Dan He,Yu-Shan Pan,Hua Wu,Gong-Zheng Hu

With the increasing and inappropriate use of colistin, the emerging colistin-resistant isolates have been frequently reported during the last few decades. Therefore, new potential targets and adjuvants to reverse colistin resistance are urgently needed. Our previous study has confirmed a marked increase of colistin susceptibility (16-fold compared to the wild-type Salmonella strain) of cpxR overexpression strain JSΔacrBΔcpxR::kan/pcpxR (simplified as JSΔΔ/pR). To searching for potential new drug targets, the transcriptome and metabolome analysis were carried out in this study. We found that the more susceptible strain JSΔΔ/pR displayed striking perturbations at both the transcriptomics and metabolomics levels. The virulence-related genes and colistin resistance-related genes (CRRGs) were significantly downregulated in JSΔΔ/pR. There were significant accumulation of citrate, α-ketoglutaric acid, and agmatine sulfate in JSΔΔ/pR, and exogenous supplement of them could synergistically enhance the bactericidal effect of colistin, indicating that these metabolites may serve as potential adjuvants for colistin therapy. Additionally, we also demonstrated that AcrB and CpxR could target the ATP and reactive oxygen species (ROS) generation, but not proton motive force (PMF) production pathway to potentiate antibacterial activity of colistin. Collectively, these findings have revealed several previously unknown mechanisms contributing to increased colistin susceptibility and identified potential targets and adjuvants for potentiating colistin treatment of Salmonella infections.IMPORTANCE Emergence of multidrug-resistant (MDR) Gram-negative (G-) bacteria have led to the reconsideration of colistin as the last-resort therapeutic option for health care-associated infections. Finding new drug targets and strategies against the spread of MDR G- bacteria are global challenges for the life sciences community and public health. In this paper, we demonstrated the more susceptibility strain JSΔΔ/pR displayed striking perturbations at both the transcriptomics and metabolomics levels and revealed several previously unknown regulatory mechanisms of AcrB and CpxR on the colistin susceptibility. Importantly, we found that exogenous supplement of citrate, α-ketoglutaric acid, and agmatine sulfate could synergistically enhance the bactericidal effect of colistin, indicating that these metabolites may serve as potential adjuvants for colistin therapy. These results provide a theoretical basis for finding potential new drug targets and adjuvants.

EefR mutations drive sanguinarine resistance by activating cryptic multidrug efflux pumps in AcrB-Null Escherichia coli

Hao-Jie Shen,Jun-Feng Wang,Zheng-Jie Xue,Jia-Qi Shi,Bing Chen,Dong-Min Chen,Ni-Pi Chen,Yu-Dong Li,Chao-Dong Qian

Antimicrobial resistance is one of the greatest threats to global health. A thorough comprehension of the underlying processes through which bacteria evolve the ability to withstand diverse stressors is vital for the development of efficacious strategies to address this challenge. This study aimed to elucidate the mechanisms underlying the adaptation of an acrB-deficient strain of Escherichia coli ATCC 35218 (35218m) to sanguinarine (SAN), the main component of phytobiotic derived from Macleaya cordata. Analysis of the in vitro-selected SAN-resistant clones of strain 35218m led to the identification of a functionally uncharacterized TetR regulator, EefR. The regulator represses its own expression and that of four neighboring genes forming the eefRABCD operon, encoding components of a tripartite RND-efflux pump (EefABC) and a putative MFS-type exporter (EefD). Overexpression of these pumps reduces the susceptibility of acrB-deficient E. coli to SAN and structurally diverse antibiotics. The eefR-eefABC-eefD cluster, widely distributed across Enterobacteriaceae genomes, is also found on plasmids in several E. coli isolates, indicating a significant risk for the rapid spread of this multidrug resistance mechanism.

Design of New Antibacterial Enhancers Based on AcrB’s Structure and the Evaluation of Their Antibacterial Enhancement Activity

Yi Song,Rongxin Qin,Xichun Pan,Qin Ouyang,Tianyu Liu,Zhaoxia Zhai,Yingchun Chen,Bin Li,Hong Zhou

Previously, artesunate (AS) and dihydroartemisinine 7 (DHA7) were found to have antibacterial enhancement activity againstEscherichia colivia inhibition of the efflux pump AcrB. However, they were only effective againstE. colistandard strains. This study aimed to develop effective antibacterial enhancers based on the previous work. Our results demonstrate that 86 new antibacterial enhancers were designed via 3D-SAR and molecular docking. Among them, DHA27 had the best antibacterial enhancement activity. It could potentiate the antibacterial effects of ampicillin against not onlyE. colistandard strain but also clinical strains, and of β-lactam antibiotics, not non-β-lactamantibiotics. DHA27 could increase the accumulation of daunomycin and nile red withinE. coliATCC 35218, but did not increase the bacterial membrane permeability. DHA27 reducedacrB’s mRNA expression ofE. coliATCC 35218 in a dose-dependent manner, and its antibacterial enhancement activity is related to the degree ofacrBmRNA expression inE. coliclinical strains. The polypeptides from AcrB were obtained via molecular docking assay; the pre-incubated polypeptides could inhibit the activity of DHA27. Importantly, DHA27 had no cytotoxicity on cell proliferation. In conclusion, among newly designed antibacterial enhancers, DHA27 had favorable physical and pharmacological properties with no significant cytotoxicity at effective concentrations, and might serve as a potential efflux pump inhibitor in the future.Keywords:antibacterial enhancer;AcrB inhibitor;DHA27;molecular mechanism

The induced and intrinsic resistance of Escherichia coli to sanguinarine is mediated by AcrB efflux pump

Jian-Sheng Dai,Jian Xu,Hao-Jie Shen,Ni-Pi Chen,Bing-Qi Zhu,Zheng-Jie Xue,Hao-Han Chen,Zhi-Shan Ding,Rui Ding,Chao-Dong Qian

Artesunate, EDTA, and colistin work synergistically against MCR-negative and -positive colistin-resistant Salmonella

Yajun Zhai,Peiyi Liu,Xueqin Hu,Changjian Fan,Xiaodie Cui,Qibiao He,Dandan He,Xiaoyuan Ma,Gongzheng Hu

Discovering new strategies to combat the multidrug-resistant bacteria constitutes a major medical challenge of our time. Previously, artesunate (AS) has been reported to exert antibacterial enhancement activity in combination with β-lactam antibiotics via inhibition of the efflux pump AcrB. However, combination of AS and colistin (COL) revealed a weak synergistic effect against a limited number of strains, and few studies have further explored its possible mechanism of synergistic action. In this article, we found that AS and EDTA could strikingly enhance the antibacterial effects of COL against mcr-1- and mcr-1+ Salmonella strains either in vitro or in vivo, when used in triple combination. The excellent bacteriostatic effect was primarily related to the increased cell membrane damage, accumulation of toxic compounds and inhibition of MCR-1. The potential binding sites of AS to MCR-1 (THR283, SER284, and TYR287) were critical for its inhibition of MCR-1 activity. Additionally, we also demonstrated that the CheA of chemosensory system and virulence-related protein SpvD were critical for the bacteriostatic synergistic effects of the triple combination. Selectively targeting CheA, SpvD, or MCR using the natural compound AS could be further investigated as an attractive strategy for the treatment of Salmonella infection. Collectively, our work opens new avenues toward the potentiation of COL and reveals an alternative drug combination strategy to overcome COL-resistant bacterial infections.

Bactericidal activity of gallic acid against multi-drug resistance Escherichia coli

QiMing Tian,SiMin Wei,HongRui Su,ShuMei Zheng,ShuYa Xu,MingJiang Liu,RuoNan Bo,JinGui Li

The continuous emergence of multidrug-resistant (MDR) bacteria has posed an increasingly serious public health threat which urges people to develop some alternatives. Gallic acid (GA) is a natural ingredient in many traditional Chinese medicines , which has many biological activities, such as antibacterial, and antiseptic. Here, clinical isolates of MDR Escherichia coli ( E. coli ) were used to evaluate the antibacterial effect of GA and the underlying mechanism. The results revealed that GA exerted bactericidal activity and inhibited the formation of bacterial biofilm. GA enhanced the activities of ceftiofur sodium or tetracycline against E. coli , and facilitated antibiotic accumulation in bacteria. Further analysis of morphological alterations and efflux pump gene expressions confirmed that GA damaged outer and inner membranes, and suppressed the mRNA expressions of acrA, acrB, tolC, acrD and acrF involved in membrane permeability . In addition, GA showed protective effects against bacterial infection and improved the survival rates of Galleria mellonella and BALB/c mice. These data highlight a better understanding of GA against bacteria and provide an alternative strategy for MDR bacterial infection.