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Rigueira LL, Perecmanis S. Concerns about the use of antimicrobials in swine herds and alternative trends. Transl Anim Sci 2024; 8:txae039. [PMID: 38685989 PMCID: PMC11056889 DOI: 10.1093/tas/txae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/15/2024] [Indexed: 05/02/2024] Open
Abstract
Pig productivity in Brazil has advanced a lot in recent decades. Specialized breeds are more vulnerable to pathogens, which has boosted the use of antimicrobials by farmers. The selective pressure generated favors the emergence of resistant bacteria, which compromises the effectiveness of this treatment and limits therapeutic options. In addition to increasing costs and mortality rates in the production system, public awareness of this issue has increased. The authorities have imposed restrictive measures to control the use of antimicrobials and have banned their use as growth promoters. This literature review highlights biosecurity and animal welfare to prevent pig diseases. Hence, we describe alternatives to the use of antimicrobials in pig production for the selection of effective non-antibiotic feed additives that help maintain good health and help the pig resist disease when infection occurs.
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Affiliation(s)
- Luciana L Rigueira
- Department of Animal Health, Brasília University, 70910-900, Brasília, Brazil
- Secretary of Agriculture of Federal District, 70770-914, Brasília, Brazil
| | - Simone Perecmanis
- Department of Animal Health, Brasília University, 70910-900, Brasília, Brazil
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2
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Yu T, Jiang X, Xu X, Xu P, Qiu S, Yin J, Hamilton DP, Jiang X. Cross-Phosphorylation between AgrC Histidine Kinase and the Noncognate Response Regulator Lmo1172 in Listeria monocytogenes under Benzalkonium Chloride Stress. Microorganisms 2024; 12:392. [PMID: 38399796 PMCID: PMC10891604 DOI: 10.3390/microorganisms12020392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/12/2024] [Accepted: 02/14/2024] [Indexed: 02/25/2024] Open
Abstract
Benzalkonium chloride (BC) is widely used for disinfection in the food industry. However, Listeria monocytogenes strains with resistance to BC have been reported recently. In L. monocytogenes, the Agr communication system consists of a membrane-bound peptidase AgrB, a precursor peptide AgrD, a histidine kinase (HK) AgrC, and a response regulator (RR) AgrA. Our previous study showed that the agr genes are significantly upregulated by BC adaptation. This study aimed to investigate the role of the Agr system in BC resistance in L. monocytogenes. Our results showed that the Agr system was involved in BC resistance. However, a direct interaction between BC and AgrC was not observed, nor between BC and AgrA. These results indicated that BC could induce the Agr system via an indirect action. Both AgrBD and AgrC were required for growth under BC stress. Nevertheless, when exposed to BC, the gene deletion mutant ∆agrA strain exhibited better growth performance than its parental strain. The RR Lmo1172 played a role in BC resistance in the ∆agrA strain, suggesting that Lmo1172 may be an alternative to AgrA in the phosphotransfer pathway. Phosphorylation of Lmo1172 by AgrC was observed in vitro. The cognate HK Lmo1173 of Lmo1172 was not involved in BC stress, regardless of whether it was as the wild-type or the ∆agrA mutant strain. Our evidence suggests that the HK AgrC cross-phosphorylates its noncognate RR Lmo1172 to cope with BC stress when the cognate RR AgrA is absent. In vivo, further studies will be required to detect phosphotransfer of AgrC/AgrA and AgrC/Lmo1172.
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Affiliation(s)
- Tao Yu
- School of Biological Engineering, Xinxiang University, Xinxiang 453003, China; (T.Y.); (X.J.); (X.X.); (P.X.)
- Australian Rivers Institute, Griffith University, Brisbane, QLD 4111, Australia;
| | - Xiaojie Jiang
- School of Biological Engineering, Xinxiang University, Xinxiang 453003, China; (T.Y.); (X.J.); (X.X.); (P.X.)
| | - Xiaobo Xu
- School of Biological Engineering, Xinxiang University, Xinxiang 453003, China; (T.Y.); (X.J.); (X.X.); (P.X.)
| | - Ping Xu
- School of Biological Engineering, Xinxiang University, Xinxiang 453003, China; (T.Y.); (X.J.); (X.X.); (P.X.)
| | - Shuxing Qiu
- Key Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Medical College, Xinxiang University, Xinxiang 453003, China; (S.Q.); (J.Y.)
| | - Junlei Yin
- Key Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Medical College, Xinxiang University, Xinxiang 453003, China; (S.Q.); (J.Y.)
| | - David P. Hamilton
- Australian Rivers Institute, Griffith University, Brisbane, QLD 4111, Australia;
| | - Xiaobing Jiang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
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3
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Jiang X, Kang R, Yu T, Jiang X, Chen H, Zhang Y, Li Y, Wang H. Cinnamaldehyde Targets the LytTR DNA-Binding Domain of the Response Regulator AgrA to Attenuate Biofilm Formation of Listeria monocytogenes. Microbiol Spectr 2023; 11:e0030023. [PMID: 37140461 PMCID: PMC10269664 DOI: 10.1128/spectrum.00300-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/19/2023] [Indexed: 05/05/2023] Open
Abstract
The Agr quorum sensing (QS) system is known to contribute to biofilm formation in Listeria monocytogenes. Cinnamaldehyde, a natural food preservative, is considered an inhibitor of Agr-mediated QS in L. monocytogenes. However, the exact mechanism by which cinnamaldehyde acts on Agr remains unclear. In this study, we assessed the effects of cinnamaldehyde on the histidine kinase AgrC and the response regulator AgrA in the Agr system. AgrC kinase activity was not influenced by cinnamaldehyde, and binding between AgrC and cinnamaldehyde was not observed when microscale thermophoresis (MST) was performed, indicating that AgrC was not the target of cinnamaldehyde. AgrA is specifically bound to the agr promoter (P2) to activate the transcription of the Agr system. However, AgrA-P2 binding was prevented by cinnamaldehyde. The interaction between cinnamaldehyde and AgrA was further confirmed with MST. Two conserved amino acids, Asn-178 and Arg-179, located in the LytTR DNA-binding domain of AgrA, were identified as the key sites for cinnamaldehyde-AgrA binding by alanine mutagenesis and MST. Coincidentally, Asn-178 was also involved in the AgrA-P2 interaction. Taken together, these results suggest that cinnamaldehyde acts as a competitive inhibitor of AgrA in AgrA-P2 binding, which leads to suppressed transcription of the Agr system and reduced biofilm formation in L. monocytogenes. IMPORTANCE Listeria monocytogenes can form biofilms on various food contact surfaces, posing a serious threat to food safety. Biofilm formation of L. monocytogenes is positively regulated by the Agr quorum sensing system. Thus, an alternative strategy for controlling L. monocytogenes biofilms is interfering with the Agr system. Cinnamaldehyde is considered an inhibitor of the L. monocytogenes Agr system; however, its exact mechanism of action is still unclear. Here, we found that AgrA (response regulator), rather than AgrC (histidine kinase), was the target of cinnamaldehyde. The conserved Asn-178 in the LytTR DNA-binding domain of AgrA was involved in cinnamaldehyde-AgrA and AgrA-P2 binding. Therefore, the occupation of Asn-178 by cinnamaldehyde suppressed transcription of the Agr system and reduced biofilm formation in L. monocytogenes. Our findings could provide a better understanding of the mechanism by which cinnamaldehyde inhibits L. monocytogenes biofilm formation.
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Affiliation(s)
- Xiaobing Jiang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Rui Kang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Tao Yu
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang, China
- Key Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Xinxiang, China
| | - Xiaojie Jiang
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang, China
| | - Hong Chen
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Yiping Zhang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Yi Li
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Hailei Wang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
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Hajiagha MN, Kafil HS. Efflux pumps and microbial biofilm formation. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2023:105459. [PMID: 37271271 DOI: 10.1016/j.meegid.2023.105459] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/25/2023] [Accepted: 05/27/2023] [Indexed: 06/06/2023]
Abstract
Biofilm-related infections are resistant forms of pathogens that are regarded as a medical problem, particularly due to the spread of multiple drug resistance. One of the factors associated with biofilm drug resistance is the presence of various types of efflux pumps in bacteria. Efflux pumps also play a role in biofilm formation by influencing Physical-chemical interactions, mobility, gene regulation, quorum sensing (QS), extracellular polymeric substances (EPS), and toxic compound extrusion. According to the findings of studies based on efflux pump expression analysis, their role in the anatomical position within the biofilm will differ depending on the biofilm formation stage, encoding gene expression level, the type and concentration of substrate. In some cases, the function of the efflux pumps can overlap with each other, so it seems necessary to accurate identify the efflux pumps of biofilm-forming bacteria along with their function in this process. Such studies will help to choose treatment strategy, at least in combination with antibiotics. Furthermore, if the goal of treatment is an efflux pump manipulation, we should not limit it to inhibition.
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Affiliation(s)
- Mahdyeh Neghabi Hajiagha
- Department of Microbiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Samadi Kafil
- Drug Applied Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
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Tomita K, Hirose A, Tanaka Y, Kouzuma A, Watanabe K. Electrogenetic control of gene expression in Shewanella oneidensis MR-1 using Arc-dependent transcriptional promoters. J Biosci Bioeng 2023:S1389-1723(23)00134-2. [PMID: 37244813 DOI: 10.1016/j.jbiosc.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/29/2023] [Accepted: 05/01/2023] [Indexed: 05/29/2023]
Abstract
Electrochemically active bacteria (EAB) are capable of electrically interacting with electrodes, enabling their application in bioelectrochemical systems (BESs). As the performance of BES is related to the metabolic activities of EAB, the development of methods to control their metabolic activities is important to facilitate BES applications. A recent study found that the EAB Shewanella oneidensis MR-1 uses the Arc system to regulate the expression of catabolic genes in response to electrode potentials, suggesting that a methodology for electrical control of gene expression in EAB, referred to as electrogenetics, can be developed by using electrode potential-responsive, Arc-dependent transcriptional promoters. Here, we explored Arc-dependent promoters in the genomes of S. oneidensis MR-1 and Escherichia coli to identify electrode potential-responsive promoters that are differentially activated in MR-1 cells exposed to high- and low-potential electrodes. LacZ reporter assays using electrode-associated cells of MR-1 derivatives revealed that the activities of promoters located upstream of the E. coli feo gene (Pfeo) and the MR-1 nqrA2 (SO_0902) gene (Pnqr2) were significantly increased when S. oneidensis cells were exposed to electrodes poised at +0.7 V and -0.4 V (versus the standard hydrogen electrode), respectively. Additionally, we developed a microscopic system for in situ monitoring of promoter activity in electrode-associated cells and found that Pnqr2 activity was persistently induced in MR-1 cells associated with an electrode poised at -0.4 V. Our results indicate that these electrode potential-responsive promoters enable efficient regulation of gene expression in EAB, providing a molecular basis for the development of electrogenetics.
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Affiliation(s)
- Keisuke Tomita
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Atsumi Hirose
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Yugo Tanaka
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Atsushi Kouzuma
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
| | - Kazuya Watanabe
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
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6
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Schwarz J, Schumacher K, Brameyer S, Jung K. Bacterial battle against acidity. FEMS Microbiol Rev 2022; 46:6652135. [PMID: 35906711 DOI: 10.1093/femsre/fuac037] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 01/09/2023] Open
Abstract
The Earth is home to environments characterized by low pH, including the gastrointestinal tract of vertebrates and large areas of acidic soil. Most bacteria are neutralophiles, but can survive fluctuations in pH. Herein, we review how Escherichia, Salmonella, Helicobacter, Brucella, and other acid-resistant Gram-negative bacteria adapt to acidic environments. We discuss the constitutive and inducible defense mechanisms that promote survival, including proton-consuming or ammonia-producing processes, cellular remodeling affecting membranes and chaperones, and chemotaxis. We provide insights into how Gram-negative bacteria sense environmental acidity using membrane-integrated and cytosolic pH sensors. Finally, we address in more detail the powerful proton-consuming decarboxylase systems by examining the phylogeny of their regulatory components and their collective functionality in a population.
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Affiliation(s)
- Julia Schwarz
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kilian Schumacher
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Sophie Brameyer
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kirsten Jung
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
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7
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Yu T, Jiang X, Xu X, Jiang C, Kang R, Jiang X. Andrographolide Inhibits Biofilm and Virulence in Listeria monocytogenes as a Quorum-Sensing Inhibitor. Molecules 2022; 27:molecules27103234. [PMID: 35630711 PMCID: PMC9145827 DOI: 10.3390/molecules27103234] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/14/2022] [Accepted: 05/17/2022] [Indexed: 12/27/2022] Open
Abstract
Listeria monocytogenes is a major foodborne pathogen that can cause listeriosis in humans and animals. Andrographolide is known as a natural antibiotic and exhibits good antibacterial activity. We aimed to investigate the effect of andrographolide on two quorum-sensing (QS) systems, LuxS/AI-2 and Agr/AIP of L. monocytogenes, as well as QS-controlled phenotypes in this study. Our results showed that neither luxS expression nor AI-2 production was affected by andrographolide. Nevertheless, andrographolide significantly reduced the expression levels of the agr genes and the activity of the agr promoter P2. Results from the crystal violet staining method, confocal laser scanning microscopy (CLSM), and field emission scanning electron microscopy (FE-SEM) demonstrated that andrographolide remarkably inhibited the biofilm-forming ability of L. monocytogenes 10403S. The preformed biofilms were eradicated when exposed to andrographolide, and reduced surviving cells were also observed in treated biofilms. L. monocytogenes treated with andrographolide exhibited decreased ability to secrete LLO and adhere to and invade Caco-2 cells. Therefore, andrographolide is a potential QS inhibitor by targeting the Agr QS system to reduce biofilm formation and virulence of L. monocytogenes.
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Affiliation(s)
- Tao Yu
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang 453000, China; (T.Y.); (X.J.); (X.X.)
- Key Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Xinxiang University, Xinxiang 453000, China
| | - Xiaojie Jiang
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang 453000, China; (T.Y.); (X.J.); (X.X.)
| | - Xiaobo Xu
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang 453000, China; (T.Y.); (X.J.); (X.X.)
| | - Congyi Jiang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang 453007, China; (C.J.); (R.K.)
| | - Rui Kang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang 453007, China; (C.J.); (R.K.)
| | - Xiaobing Jiang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang 453007, China; (C.J.); (R.K.)
- Correspondence: ; Tel.: +86-03733326340
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8
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Jiang X, Jiang C, Yu T, Jiang X, Ren S, Kang R, Qiu S. Benzalkonium Chloride Adaptation Increases Expression of the Agr System, Biofilm Formation, and Virulence in Listeria monocytogenes. Front Microbiol 2022; 13:856274. [PMID: 35283841 PMCID: PMC8905296 DOI: 10.3389/fmicb.2022.856274] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
Benzalkonium chloride (BC) is widely used for disinfection in food industry. However, prolonged exposure to BC may lead to the emergence of BC adapted strains of Listeria monocytogenes, an important foodborne pathogen. Until now, two communication systems, the LuxS/AI-2 system and the Agr system, have been identified in L. monocytogenes. This study aimed to investigate the role of communication systems in BC adaptation and the effect of BC adaptation on two communication systems and the communication-controlled behaviors in L. monocytogenes. Results demonstrated that the Agr system rather than the LuxS system plays an important role in BC adaptation of L. monocytogenes. Neither luxS expression nor AI-2 production was affected by BC adaptation. On the other hand, the expression of the agr operon and the activity of the agr promoter were significantly increased after BC adaptation. BC adaptation enhanced biofilm formation of L. monocytogenes. However, swarming motility was reduced by BC adaptation. Data from qRT-PCR showed that flagella-mediated motility-related genes (flaA, motA, and motB) were downregulated in BC adapted strains. BC adaptation increased the ability of L. monocytogenes to adhere to and invade Caco-2 cells but did not affect the hemolytic activity. Compared with the wild-type strains, the expression levels of virulence genes prfA, plcA, mpl, actA, and plcB increased more than 2-fold in BC adapted strains; however, lower than 2-fold changes in the expression of hemolysis-associated gene hly were observed. Our study suggests that BC adaptation could increase the expression of the Agr system and enhance biofilm formation, invasion, and virulence of L. monocytogenes, which brings about threats to food safety and public health. Therefore, effective measures should be taken to avoid the emergence of BC adapted strains of L. monocytogenes.
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Affiliation(s)
- Xiaobing Jiang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Congyi Jiang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Tao Yu
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang, China.,Key Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Xinxiang, China
| | - Xiaojie Jiang
- School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang, China
| | - Siyu Ren
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Rui Kang
- Henan Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Shuxing Qiu
- Key Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Xinxiang, China
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Jian Z, Zeng L, Xu T, Sun S, Yan S, Yang L, Huang Y, Jia J, Dou T. Antibiotic resistance genes in bacteria: Occurrence, spread, and control. J Basic Microbiol 2021; 61:1049-1070. [PMID: 34651331 DOI: 10.1002/jobm.202100201] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 09/11/2021] [Accepted: 09/26/2021] [Indexed: 11/07/2022]
Abstract
The production and use of antibiotics are becoming increasingly common worldwide, and the problem of antibiotic resistance is increasing alarmingly. Drug-resistant infections threaten human life and health and impose a heavy burden on the global economy. The origin and molecular basis of bacterial resistance is the presence of antibiotic resistance genes (ARGs). Investigations on ARGs mostly focus on the environments in which antibiotics are frequently used, such as hospitals and farms. This literature review summarizes the current knowledge of the occurrence of antibiotic-resistant bacteria in nonclinical environments, such as air, aircraft wastewater, migratory bird feces, and sea areas in-depth, which have rarely been involved in previous studies. Furthermore, the mechanism of action of plasmid and phage during horizontal gene transfer was analyzed, and the transmission mechanism of ARGs was summarized. This review highlights the new mechanisms that enhance antibiotic resistance and the evolutionary background of multidrug resistance; in addition, some promising points for controlling or reducing the occurrence and spread of antimicrobial resistance are also proposed.
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Affiliation(s)
- Zonghui Jian
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Li Zeng
- The Chenggong Department, Kunming Medical University Affiliated Stomatological Hospital, Kunming, Yunnan, China
| | - Taojie Xu
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Shuai Sun
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Shixiong Yan
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Lan Yang
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Ying Huang
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Junjing Jia
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Tengfei Dou
- Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming, Yunnan, China
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10
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Schaffner SH, Lee AV, Pham MTN, Kassaye BB, Li H, Tallada S, Lis C, Lang M, Liu Y, Ahmed N, Galbraith LG, Moore JP, Bischof KM, Menke CC, Slonczewski JL. Extreme Acid Modulates Fitness Trade-Offs of Multidrug Efflux Pumps MdtEF-TolC and AcrAB-TolC in Escherichia coli K-12. Appl Environ Microbiol 2021; 87:e0072421. [PMID: 34085861 PMCID: PMC8315180 DOI: 10.1128/aem.00724-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/29/2021] [Indexed: 12/26/2022] Open
Abstract
Bacterial genomes encode various multidrug efflux pumps (MDR) whose specific conditions for fitness advantage are unknown. We show that the efflux pump MdtEF-TolC, in Escherichia coli, confers a fitness advantage during exposure to extreme acid (pH 2). Our flow cytometry method revealed pH-dependent fitness trade-offs between bile acids (a major pump substrate) and salicylic acid, a membrane-permeant aromatic acid that induces a drug resistance regulon but depletes proton motive force (PMF). The PMF drives MdtEF-TolC and related pumps such as AcrAB-TolC. Deletion of mdtE (with loss of the pump MdtEF-TolC) increased the strain's relative fitness during growth with or without salicylate or bile acids. However, when the growth cycle included a 2-h incubation at pH 2 (below the pH growth range), MdtEF-TolC conferred a fitness advantage. The fitness advantage required bile salts but was decreased by the presence of salicylate, whose uptake is amplified by acid. For comparison, AcrAB-TolC, the primary efflux pump for bile acids, conferred a PMF-dependent fitness advantage with or without acid exposure in the growth cycle. A different MDR pump, EmrAB-TolC, conferred no selective benefit during growth in the presence of bile acids. Without bile acids, all three MDR pumps incurred a large fitness cost with salicylate when exposed at pH 2. These results are consistent with the increased uptake of salicylate at low pH. Overall, we showed that MdtEF-TolC is an MDR pump adapted for transient extreme-acid exposure and that low pH amplifies the salicylate-dependent fitness cost for drug pumps. IMPORTANCE Antibiotics and other drugs that reach the gut must pass through stomach acid. However, little is known of how extreme acid modulates the effect of drugs on gut bacteria. We find that extreme-acid exposure leads to a fitness advantage for a multidrug pump that otherwise incurs a fitness cost. At the same time, extreme acid amplifies the effect of salicylate selection against multidrug pumps. Thus, organic acids and stomach acid could play important roles in regulating multidrug resistance in the gut microbiome. Our flow cytometry assay provides a way to measure the fitness effects of extreme-acid exposure to various membrane-soluble organic acids, including plant-derived nutrients and pharmaceutical agents. Therapeutic acids might be devised to control the prevalence of multidrug pumps in environmental and host-associated habitats.
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Affiliation(s)
| | - Abigail V. Lee
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | | | - Haofan Li
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | - Cassandra Lis
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Mark Lang
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Yangyang Liu
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Nafeez Ahmed
- Department of Biology, Kenyon College, Gambier, Ohio, USA
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11
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Inada S, Okajima T, Utsumi R, Eguchi Y. Acid-Sensing Histidine Kinase With a Redox Switch. Front Microbiol 2021; 12:652546. [PMID: 34093469 PMCID: PMC8174306 DOI: 10.3389/fmicb.2021.652546] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/19/2021] [Indexed: 12/22/2022] Open
Abstract
The EvgS/EvgA two-component signal transduction system in Escherichia coli is activated under mildly acidic pH conditions. Upon activation, this system induces the expression of a number of genes that confer acid resistance. The EvgS histidine kinase sensor has a large periplasmic domain that is required for perceiving acidic signals. In addition, we have previously proposed that the cytoplasmic linker region of EvgS is also involved in the activation of this sensor. The cytoplasmic linker region resembles a Per-ARNT-Sim (PAS) domain, which is known to act as a molecular sensor that is responsive to chemical and physical stimuli and regulates the activity of diverse effector domains. Our EvgS/EvgA reporter assays revealed that under EvgS-activating mildly acidic pH conditions, EvgS was activated only during aerobic growth conditions, and not during anaerobic growth. Studies using EvgS mutants revealed that C671A and C683A mutations in the cytoplasmic PAS domain activated EvgS even under anaerobic conditions. Furthermore, among the electron carriers of the electron transport chain, ubiquinone was required for EvgS activation. The present study proposes a model of EvgS activation by oxidation and suggests that the cytoplasmic PAS domain serves as an intermediate redox switch for this sensor.
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Affiliation(s)
- Shinya Inada
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Japan
| | - Toshihide Okajima
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Japan
| | - Ryutaro Utsumi
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Japan
| | - Yoko Eguchi
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Japan
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12
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Sheikh SW, Ali A, Ahsan A, Shakoor S, Shang F, Xue T. Insights into Emergence of Antibiotic Resistance in Acid-Adapted Enterohaemorrhagic Escherichia coli. Antibiotics (Basel) 2021; 10:522. [PMID: 34063307 PMCID: PMC8147483 DOI: 10.3390/antibiotics10050522] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/15/2021] [Accepted: 04/29/2021] [Indexed: 12/17/2022] Open
Abstract
The emergence of multidrug-resistant pathogens presents a global challenge for treating and preventing disease spread through zoonotic transmission. The water and foodborne Enterohaemorrhagic Escherichia coli (EHEC) are capable of causing intestinal and systemic diseases. The root cause of the emergence of these strains is their metabolic adaptation to environmental stressors, especially acidic pH. Acid treatment is desired to kill pathogens, but the protective mechanisms employed by EHECs cross-protect against antimicrobial peptides and thus facilitate opportunities for survival and pathogenesis. In this review, we have discussed the correlation between acid tolerance and antibiotic resistance, highlighting the identification of novel targets for potential production of antimicrobial therapeutics. We have also summarized the molecular mechanisms used by acid-adapted EHECs, such as the two-component response systems mediating structural modifications, competitive inhibition, and efflux activation that facilitate cross-protection against antimicrobial compounds. Moving beyond the descriptive studies, this review highlights low pH stress as an emerging player in the development of cross-protection against antimicrobial agents. We have also described potential gene targets for innovative therapeutic approaches to overcome the risk of multidrug-resistant diseases in healthcare and industry.
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Affiliation(s)
- Salma Waheed Sheikh
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China;
| | - Ahmad Ali
- School of Agronomy, Anhui Agricultural University, Hefei 230036, China;
| | - Asma Ahsan
- Faculty of Life Sciences, University of Central Punjab, Lahore 54000, Punjab, Pakistan;
| | - Sidra Shakoor
- Station de Neucfchateau, CIRAD, 97130 Sainte-Marie, Capesterre Belle Eau, Guadeloupe, France;
| | - Fei Shang
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China;
| | - Ting Xue
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China;
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13
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Henderson PJF, Maher C, Elbourne LDH, Eijkelkamp BA, Paulsen IT, Hassan KA. Physiological Functions of Bacterial "Multidrug" Efflux Pumps. Chem Rev 2021; 121:5417-5478. [PMID: 33761243 DOI: 10.1021/acs.chemrev.0c01226] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacterial multidrug efflux pumps have come to prominence in human and veterinary pathogenesis because they help bacteria protect themselves against the antimicrobials used to overcome their infections. However, it is increasingly realized that many, probably most, such pumps have physiological roles that are distinct from protection of bacteria against antimicrobials administered by humans. Here we undertake a broad survey of the proteins involved, allied to detailed examples of their evolution, energetics, structures, chemical recognition, and molecular mechanisms, together with the experimental strategies that enable rapid and economical progress in understanding their true physiological roles. Once these roles are established, the knowledge can be harnessed to design more effective drugs, improve existing microbial production of drugs for clinical practice and of feedstocks for commercial exploitation, and even develop more sustainable biological processes that avoid, for example, utilization of petroleum.
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Affiliation(s)
- Peter J F Henderson
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Claire Maher
- School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, New South Wales, Australia
| | - Liam D H Elbourne
- Department of Biomolecular Sciences, Macquarie University, Sydney 2109, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
| | - Bart A Eijkelkamp
- College of Science and Engineering, Flinders University, Bedford Park 5042, South Australia, Australia
| | - Ian T Paulsen
- Department of Biomolecular Sciences, Macquarie University, Sydney 2109, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
| | - Karl A Hassan
- School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
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14
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Mapping the Transcriptional and Fitness Landscapes of a Pathogenic E. coli Strain: The Effects of Organic Acid Stress under Aerobic and Anaerobic Conditions. Genes (Basel) 2020; 12:genes12010053. [PMID: 33396416 PMCID: PMC7824302 DOI: 10.3390/genes12010053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 12/31/2022] Open
Abstract
Several methods are available to probe cellular responses to external stresses at the whole genome level. RNAseq can be used to measure changes in expression of all genes following exposure to stress, but gives no information about the contribution of these genes to an organism’s ability to survive the stress. The relative contribution of each non-essential gene in the genome to the fitness of the organism under stress can be obtained using methods that use sequencing to estimate the frequencies of members of a dense transposon library grown under different conditions, for example by transposon-directed insertion sequencing (TraDIS). These two methods thus probe different aspects of the underlying biology of the organism. We were interested to determine the extent to which the data from these two methods converge on related genes and pathways. To do this, we looked at a combination of biologically meaningful stresses. The human gut contains different organic short-chain fatty acids (SCFAs) produced by fermentation of carbon compounds, and Escherichia coli is exposed to these in its passage through the gut. Their effect is likely to depend on both the ambient pH and the level of oxygen present. We, therefore, generated RNAseq and TraDIS data on a uropathogenic E. coli strain grown at either pH 7 or pH 5.5 in the presence or absence of three SCFAs (acetic, propionic and butyric), either aerobically or anaerobically. Our analysis identifies both known and novel pathways as being likely to be important under these conditions. There is no simple correlation between gene expression and fitness, but we found a significant overlap in KEGG pathways that are predicted to be enriched following analysis of the data from the two methods, and the majority of these showed a fitness signature that would be predicted from the gene expression data, assuming expression to be adaptive. Genes which are not in the E. coli core genome were found to be particularly likely to show a positive correlation between level of expression and contribution to fitness.
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15
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Sun H, Song Y, Chen F, Zhou C, Liu P, Fan Y, Zheng Y, Wan X, Feng L. An ArcA-Modulated Small RNA in Pathogenic Escherichia coli K1. Front Microbiol 2020; 11:574833. [PMID: 33329434 PMCID: PMC7719688 DOI: 10.3389/fmicb.2020.574833] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 10/23/2020] [Indexed: 02/05/2023] Open
Abstract
Escherichia coli K1 is the leading cause of meningitis in newborns. Understanding the molecular basis of E. coli K1 pathogenicity will help develop treatment of meningitis and prevent neurological sequelae. E. coli K1 replicates in host blood and forms a high level of bacteremia to cause meningitis in human. However, the mechanisms that E. coli K1 employs to sense niche signals for survival in host blood are poorly understood. We identified one intergenic region in E. coli K1 genome that encodes a novel small RNA, sRNA-17. The expression of sRNA-17 was downregulated by ArcA in microaerophilic blood. The ΔsRNA-17 strain grew better in blood than did the wild-type strain and enhanced invasion frequency in human brain microvascular endothelial cells. Transcriptome analyses revealed that sRNA-17 regulates tens of differentially expressed genes. These data indicate that ArcA downregulates the sRNA-17 expression to benefit bacterial survival in blood and penetration of the blood–brain barrier. Our findings reveal a signaling mechanism in E. coli K1 for host adaptation.
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Affiliation(s)
- Hao Sun
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China.,College of Life Sciences, Nankai University, Tianjin, China
| | - Yajun Song
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China.,College of Life Sciences, Nankai University, Tianjin, China
| | - Fang Chen
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China
| | - Changhong Zhou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China
| | - Peng Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China
| | - Yu Fan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China
| | - Yangyang Zheng
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China.,College of Life Sciences, Nankai University, Tianjin, China
| | - Xuehua Wan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China
| | - Lu Feng
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China.,College of Life Sciences, Nankai University, Tianjin, China
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16
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The Roles of Microbial Cell-Cell Chemical Communication Systems in the Modulation of Antimicrobial Resistance. Antibiotics (Basel) 2020; 9:antibiotics9110779. [PMID: 33171916 PMCID: PMC7694446 DOI: 10.3390/antibiotics9110779] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 01/25/2023] Open
Abstract
Rapid emergence of antimicrobial resistance (AMR) has become a critical challenge worldwide. It is of great importance to understand how AMR is modulated genetically in order to explore new antimicrobial strategies. Recent studies have unveiled that microbial communication systems, which are known to play key roles in regulation of bacterial virulence, are also associated with the formation and regulation of AMR. These microbial cell-to-cell chemical communication systems, including quorum sensing (QS) and pathogen-host communication mechanisms, rely on detection and response of various chemical signal molecules, which are generated either by the microbe itself or host cells, to activate the expression of virulence and AMR genes. This article summarizes the generic signaling mechanisms of representative QS and pathogen-host communications systems, reviews the current knowledge regarding the roles of these chemical communication systems in regulation of AMR, and describes the strategies developed over the years for blocking bacterial chemical communication systems in disease control. The research progress in this field suggests that the bacterial cell-cell communication systems are a promising target not only for disease control but also for curbing the problem of microbial drug resistance.
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17
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Fanelli G, Pasqua M, Colonna B, Prosseda G, Grossi M. Expression Profile of Multidrug Resistance Efflux Pumps During Intracellular Life of Adherent-Invasive Escherichia coli Strain LF82. Front Microbiol 2020; 11:1935. [PMID: 33013734 PMCID: PMC7462009 DOI: 10.3389/fmicb.2020.01935] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/22/2020] [Indexed: 01/15/2023] Open
Abstract
Efflux pumps (EPs) are present in all living cells and represent a large and important group of transmembrane proteins involved in transport processes. In bacteria, multidrug resistance efflux pumps (MDR EPs) confer resistance to antibiotics at different levels and are deeply implicated in the fast and dramatic emergence of antibiotic resistance. Recently, several reports have outlined the great versatility of MDR EPs in exporting a large variety of compounds other than antibiotics, thus promoting bacterial adaptation to a wide range of habitats. In several bacterial pathogens, MDR EPs contribute to increase the virulence potential and are directly involved in the crosstalk with host cells. In this work, we have investigated the possible role of MDR EPs in the infectious process of the adherent-invasive Escherichia coli (AIEC), a group of pathogenic E. coli that colonize the ileal mucosa of Crohn disease (CD) patients causing a strong intestinal inflammation. The results we have obtained indicate that, with the exception of mdtM, all MDR-EPs encoding genes present in E.coli K12 are conserved in the AIEC prototype strain LF82. The analysis of MDR EP expression during LF82 infection of macrophages and epithelial cells reveals that their transcription is highly modulated during the bacterial intracellular life. Notably, some EP genes are regulated in a cell-type specific manner, strongly suggesting that their function is required for LF82 successful infection. AIEC are able to adhere to and invade intestinal epithelial cells and, importantly, to survive and multiply within macrophages. Thus, we further investigated the role of EPs specifically induced by macrophage environment. We present evidence indicating that deletion of mdtEF genes, encoding an MDR EP belonging to the resistance nodulation division (RND) family, significantly impairs survival of LF82 in macrophages and that the wild type phenotype can be restored by trans-complementation with functional MdtEF pump. Altogether, our results indicate a strong involvement of MDR EPs in host pathogen interaction also in AIEC and highlight the contribution of MdtEF to the fitness of LF82 in the macrophage environment.
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Affiliation(s)
- Giulia Fanelli
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza-Università di Roma, Rome, Italy
| | - Martina Pasqua
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza-Università di Roma, Rome, Italy
| | - Bianca Colonna
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza-Università di Roma, Rome, Italy
| | - Gianni Prosseda
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza-Università di Roma, Rome, Italy
| | - Milena Grossi
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza-Università di Roma, Rome, Italy
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18
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Interactions between DksA and Stress-Responsive Alternative Sigma Factors Control Inorganic Polyphosphate Accumulation in Escherichia coli. J Bacteriol 2020; 202:JB.00133-20. [PMID: 32341074 DOI: 10.1128/jb.00133-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/21/2020] [Indexed: 01/24/2023] Open
Abstract
Bacteria synthesize inorganic polyphosphate (polyP) in response to a variety of different stress conditions. polyP protects bacteria by acting as a protein-stabilizing chaperone, metal chelator, or regulator of protein function, among other mechanisms. However, little is known about how stress signals are transmitted in the cell to lead to increased polyP accumulation. Previous work in the model enterobacterium Escherichia coli has indicated that the RNA polymerase-binding regulatory protein DksA is required for polyP synthesis in response to nutrient limitation stress. In this work, I set out to characterize the role of DksA in polyP regulation in more detail. I found that overexpression of DksA increases cellular polyP content (explaining the long-mysterious phenotype of dksA overexpression rescuing growth of a dnaK mutant at high temperatures) and characterized the roles of known functional residues of DksA in this process, finding that binding to RNA polymerase is required but that none of the other functions of DksA appear to be necessary. Transcriptomics revealed genome-wide transcriptional changes upon nutrient limitation, many of which were affected by DksA, and follow-up experiments identified complex interactions between DksA and the stress-sensing alternative sigma factors FliA, RpoN, and RpoE that impact polyP production, indicating that regulation of polyP synthesis is deeply entwined in the multifactorial stress response network of E. coli IMPORTANCE Inorganic polyphosphate (polyP) is an evolutionarily ancient, widely conserved biopolymer required for stress resistance and pathogenesis in diverse bacteria, but we do not understand how its synthesis is regulated. In this work, I gained new insights into this process by characterizing the role of the transcriptional regulator DksA in polyP regulation in Escherichia coli and identifying previously unknown links between polyP synthesis and the stress-responsive alternative sigma factors FliA, RpoN, and RpoE.
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19
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Jiang X, Ren S, Geng Y, Yu T, Li Y, Liu L, Liu G, Wang H, Shi L. The sug operon involves in resistance to quaternary ammonium compounds in Listeria monocytogenes EGD-e. Appl Microbiol Biotechnol 2020; 104:7093-7104. [DOI: 10.1007/s00253-020-10741-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 06/02/2020] [Accepted: 06/09/2020] [Indexed: 02/07/2023]
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20
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Xu Z, Wang P, Wang H, Yu ZH, Au-Yeung HY, Hirayama T, Sun H, Yan A. Zinc excess increases cellular demand for iron and decreases tolerance to copper in Escherichia coli. J Biol Chem 2019; 294:16978-16991. [PMID: 31586033 DOI: 10.1074/jbc.ra119.010023] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/25/2019] [Indexed: 12/11/2022] Open
Abstract
Transition metals serve as an important class of micronutrients that are indispensable for bacterial physiology but are cytotoxic when they are in excess. Bacteria have developed exquisite homeostatic systems to control the uptake, storage, and efflux of each of biological metals and maintain a thermodynamically balanced metal quota. However, whether the pathways that control the homeostasis of different biological metals cross-talk and render cross-resistance or sensitivity in the host-pathogen interface remains largely unknown. Here, we report that zinc (Zn) excess perturbs iron (Fe) and copper (Cu) homeostasis in Escherichia coli, resulting in increased Fe and decreased Cu levels in the cell. Gene expression analysis revealed that Zn excess transiently up-regulates Fe-uptake genes and down-regulates Fe-storage genes and thereby increases the cellular Fe quota. In vitro and in vivo protein-DNA binding assays revealed that the elevated intracellular Fe poisons the primary Cu detoxification transcription regulator CueR, resulting in dysregulation of its target genes copA and cueO and activation of the secondary Cu detoxification system CusSR-cusCFBA Supplementation with the Fe chelator 2,2'-dipyridyl (DIP) or with the reducing agent GSH abolished the induction of cusCFBA during Zn excess. Consistent with the importance of this metal homeostatic network in cell physiology, combined metal treatment, including simultaneously overloading cells with both Zn (0.25 mm) and Cu (0.25 mm) and sequestering Fe with DIP (50 μm), substantially inhibited E. coli growth. These results advance our understanding of bacterial metallobiology and may inform the development of metal-based antimicrobial regimens to manage infectious diseases.
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Affiliation(s)
- Zeling Xu
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Pengchao Wang
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Haibo Wang
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Zuo Hang Yu
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ho Yu Au-Yeung
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Tasuku Hirayama
- Laboratory of Pharmaceutical and Medicinal Chemistry, Gifu Pharmaceutical University, 1-25-4, Dairaku-nishi, Gifu, 501-1196, Japan
| | - Hongzhe Sun
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Aixin Yan
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China
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21
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The VirAB-VirSR-AnrAB Multicomponent System Is Involved in Resistance of Listeria monocytogenes EGD-e to Cephalosporins, Bacitracin, Nisin, Benzalkonium Chloride, and Ethidium Bromide. Appl Environ Microbiol 2019; 85:AEM.01470-19. [PMID: 31399408 DOI: 10.1128/aem.01470-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 08/01/2019] [Indexed: 02/06/2023] Open
Abstract
In Listeria monocytogenes, it has been proposed that the VirSR two-component signal transduction systems (TCSs) and two ATP-binding cassette (ABC) transporters, VirAB and AnrAB, constitute a complex TCS/ABC transporter system which has been recognized as a unique resistance mode. The role of the putative VirAB-VirSR-AnrAB system in antimicrobial resistance and the respective contributions of the members of the system to resistance were investigated in this study. We constructed gene deletion mutants of L. monocytogenes EGD-e and complemented strains of the mutants and determined MICs of antimicrobial agents against these strains against using the agar dilution method. We assessed the relative expression levels of target genes by reverse transcription-quantitative PCR (RT-qPCR) and measured promoter activity levels by β-galactosidase assays. Our results showed that the VirAB-VirSR-AnrAB system mediates not only nisin and bacitracin resistance but also resistance to cephalosporins, ethidium bromide (EtBr), and benzalkonium chloride (BC). In this system, two ABC transporters, VirAB and AnrAB, play distinct roles in cefotaxime resistance: the former is responsible only for antimicrobial sensing and signaling by VirSR, while the latter contributes to transportation of antimicrobials. Notably, VirAB itself, rather than the VirAB-VirSR-AnrAB system as a whole, contributes to kanamycin and tetracycline resistance. On the basis of the results obtained from this study, we speculate that VirAB acts as a sensor for VirSR in response to cephalosporins, bacitracin, nisin, EtBr, and BC, while VirAB itself plays a role in response to kanamycin and tetracycline in L. monocytogenes EGD-e.IMPORTANCE This report describes TCS/ABC transporter modules characterized in Listeria monocytogenes EGD-e. The modules consist of the VirSR TCS and the VirAB and AnrAB ABC transporters. Our results showed that this system is involved in nisin and bacitracin resistance, as well as resistance to cephalosporins, ethidium bromide (EtBr), and benzalkonium chloride (BC). In this system, VirAB is responsible only for antimicrobial sensing and signaling by VirSR, while AnrAB contributes to transportation of antimicrobials. Interestingly, VirAB itself, rather than the VirAB-VirSR-AnrAB system as a whole, contributes to kanamycin and tetracycline resistance.
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22
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Moore JP, Li H, Engmann ML, Bischof KM, Kunka KS, Harris ME, Tancredi AC, Ditmars FS, Basting PJ, George NS, Bhagwat AA, Slonczewski JL. Inverted Regulation of Multidrug Efflux Pumps, Acid Resistance, and Porins in Benzoate-Evolved Escherichia coli K-12. Appl Environ Microbiol 2019; 85:e00966-19. [PMID: 31175192 PMCID: PMC6677852 DOI: 10.1128/aem.00966-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 05/30/2019] [Indexed: 01/23/2023] Open
Abstract
Benzoic acid, a partial uncoupler of the proton motive force (PMF), selects for sensitivity to chloramphenicol and tetracycline during the experimental evolution of Escherichia coli K-12. Transcriptomes of E. coli isolates evolved with benzoate showed the reversal of benzoate-dependent regulation, including the downregulation of multidrug efflux pump genes, the gene for the Gad acid resistance regulon, the nitrate reductase genes narHJ, and the gene for the acid-consuming hydrogenase Hyd-3. However, the benzoate-evolved strains had increased expression of OmpF and other large-hole porins that admit fermentable substrates and antibiotics. Candidate genes identified from benzoate-evolved strains were tested for their roles in benzoate tolerance and in chloramphenicol sensitivity. Benzoate or salicylate tolerance was increased by deletion of the Gad activator ariR or of the acid fitness island from slp to the end of the gadX gene encoding Gad regulators and the multidrug pump genes mdtEF Benzoate tolerance was also increased by deletion of multidrug component gene emrA, RpoS posttranscriptional regulator gene cspC, adenosine deaminase gene add, hydrogenase gene hyc (Hyd-3), and the RNA chaperone/DNA-binding regulator gene hfq Chloramphenicol resistance was decreased by mutations in genes for global regulators, such as RNA polymerase alpha subunit gene rpoA, the Mar activator gene rob, and hfq Deletion of lipopolysaccharide biosynthetic kinase gene rfaY decreased the rate of growth in chloramphenicol. Isolates from experimental evolution with benzoate had many mutations affecting aromatic biosynthesis and catabolism, such as aroF (encoding tyrosine biosynthesis) and apt (encoding adenine phosphoribosyltransferase). Overall, benzoate or salicylate exposure selects for the loss of multidrug efflux pumps and of hydrogenases that generate a futile cycle of PMF and upregulates porins that admit fermentable nutrients and antibiotics.IMPORTANCE Benzoic acid is a common food preservative, and salicylic acid (2-hydroxybenzoic acid) is the active form of aspirin. At high concentrations, benzoic acid conducts a proton across the membrane, depleting the proton motive force. In the absence of antibiotics, benzoate exposure selects against proton-driven multidrug efflux pumps and upregulates porins that admit fermentable substrates but that also allow the entry of antibiotics. Thus, evolution with benzoate and related molecules, such as salicylates, requires a trade-off for antibiotic sensitivity, a trade-off that could help define a stable gut microbiome. Benzoate and salicylate are naturally occurring plant signal molecules that may modulate the microbiomes of plants and animal digestive tracts so as to favor fermenters and exclude drug-resistant pathogens.
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Affiliation(s)
- Jeremy P Moore
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Haofan Li
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | | | - Karina S Kunka
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Mary E Harris
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | | | | | - Nadja S George
- Environmental Microbiology and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, Maryland, USA
| | - Arvind A Bhagwat
- Environmental Microbiology and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Beltsville, Maryland, USA
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Experimental Evolution of Escherichia coli K-12 in the Presence of Proton Motive Force (PMF) Uncoupler Carbonyl Cyanide m-Chlorophenylhydrazone Selects for Mutations Affecting PMF-Driven Drug Efflux Pumps. Appl Environ Microbiol 2019; 85:AEM.02792-18. [PMID: 30578262 DOI: 10.1128/aem.02792-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 12/06/2018] [Indexed: 01/10/2023] Open
Abstract
Experimental evolution of Escherichia coli K-12 with benzoate, a partial uncoupler of the proton motive force (PMF), selects for mutations that decrease antibiotic resistance. We conducted experimental evolution in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), a strong uncoupler. Cultures were serially diluted daily 1:100 in LBK medium containing 20 to 150 µM CCCP buffered at pH 6.5 or at pH 8.0. After 1,000 generations, the populations tolerated up to 150 µM CCCP. Sequenced isolates had mutations in mprA (emrR), which downregulates the EmrAB-TolC pump that exports CCCP. A mprA::kanR deletion conferred growth at 60 μM CCCP, though not at the higher levels resisted by evolved strains (150 µM). Some mprA mutant strains also had point mutations affecting emrA, but deletion of emrA abolished the CCCP resistance. Thus, CCCP-evolved isolates contained additional adaptations. One isolate lacked emrA or mprA mutations but had mutations in cecR (ybiH), whose product upregulates drug pumps YbhG and YbhFSR, and in gadE, which upregulates the multidrug pump MdtEF. A cecR::kanR deletion conferred partial resistance to CCCP. Other multidrug efflux genes that had mutations included ybhR and acrAB The acrB isolate was sensitive to the AcrAB substrates chloramphenicol and tetracycline. Other mutant genes in CCCP-evolved strains include rng (RNase G) and cyaA (adenylate cyclase). Overall, experimental evolution revealed a CCCP-dependent fitness advantage for mutations increasing CCCP efflux via EmrA and for mutations that may deactivate proton-driven pumps for drugs not present (cecR, gadE, acrAB, and ybhR). These results are consistent with our previous report of drug sensitivity associated with evolved benzoate tolerance.IMPORTANCE The genetic responses of bacteria to depletion of proton motive force (PMF), and their effects on drug resistance, are poorly understood. PMF drives export of many antibiotics, but the energy cost may decrease fitness when antibiotics are absent. Our evolution experiment reveals genetic mechanisms of adaptation to the PMF uncoupler CCCP, including selection for increased CCCP efflux but also against the expression of PMF-driven pumps for drugs not present. The results have implications for our understanding of the gut microbiome, which experiences high levels of organic acids that decrease PMF.
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MdrL, a major facilitator superfamily efflux pump of
Listeria monocytogenes
involved in tolerance to benzalkonium chloride. Appl Microbiol Biotechnol 2018; 103:1339-1350. [DOI: 10.1007/s00253-018-9551-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/21/2018] [Accepted: 11/30/2018] [Indexed: 12/16/2022]
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Microbial Cell Factories à la Carte: Elimination of Global Regulators Cra and ArcA Generates Metabolic Backgrounds Suitable for the Synthesis of Bioproducts in Escherichia coli. Appl Environ Microbiol 2018; 84:AEM.01337-18. [PMID: 30030227 DOI: 10.1128/aem.01337-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/16/2018] [Indexed: 11/20/2022] Open
Abstract
Manipulation of global regulators is one of the strategies used for the construction of bacterial strains suitable for the synthesis of bioproducts. However, the pleiotropic effects of these regulators can vary under different conditions and are often strain dependent. This study analyzed the effects of ArcA, CreC, Cra, and Rob using single deletion mutants of the well-characterized and completely sequenced Escherichia coli strain BW25113. Comparison of the effects of each regulator on the synthesis of major extracellular metabolites, tolerance to several compounds, and synthesis of native and nonnative bioproducts under different growth conditions allowed the discrimination of the particular phenotypes that can be attributed to the individual mutants and singled out Cra and ArcA as the regulators with the most important effects on bacterial metabolism. These data were used to identify the most suitable backgrounds for the synthesis of the reduced bioproducts succinate and 1,3-propanediol (1,3-PDO). The Δcra mutant was further modified to enhance succinate synthesis by the addition of enzymes that increase NADH and CO2 availability, achieving an 80% increase compared to the parental strain. Production of 1,3-PDO in the ΔarcA mutant was optimized by overexpression of PhaP, which increased more than twice the amount of the diol compared to the wild type in a semidefined medium using glycerol, resulting in 24 g · liter-1 of 1,3-PDO after 48 h, with a volumetric productivity of 0.5 g · liter-1 h-1 IMPORTANCE Although the effects of many global regulators, especially ArcA and Cra, have been studied in Escherichia coli, the metabolic changes caused by the absence of global regulators have been observed to differ between strains. This scenario complicates the identification of the individual effects of the regulators, which is essential for the design of metabolic engineering strategies. The genome of Escherichia coli BW25113 has been completely sequenced and does not contain additional mutations that could mask or interfere with the effects of the global regulator mutations. The uniform genetic background of the Keio collection mutants enabled the characterization of the physiological consequences of altered carbon and redox fluxes caused by each global regulator deletion, eliminating possible strain-dependent results. As a proof of concept, Δcra and ΔarcA mutants were subjected to further manipulations to obtain large amounts of succinate and 1,3-PDO, demonstrating that the metabolic backgrounds of the mutants were suitable for the synthesis of bioproducts.
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Rodionova IA, Goodacre N, Do J, Hosseinnia A, Babu M, Uetz P, Saier MH. The uridylyltransferase GlnD and tRNA modification GTPase MnmE allosterically control Escherichia coli folylpoly-γ-glutamate synthase FolC. J Biol Chem 2018; 293:15725-15732. [PMID: 30089654 DOI: 10.1074/jbc.ra118.004425] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 07/31/2018] [Indexed: 01/20/2023] Open
Abstract
Folate derivatives are important cofactors for enzymes in several metabolic processes. Folate-related inhibition and resistance mechanisms in bacteria are potential targets for antimicrobial therapies and therefore a significant focus of current research. Here, we report that the activity of Escherichia coli poly-γ-glutamyl tetrahydrofolate/dihydrofolate synthase (FolC) is regulated by glutamate/glutamine-sensing uridylyltransferase (GlnD), THF-dependent tRNA modification enzyme (MnmE), and UDP-glucose dehydrogenase (Ugd) as shown by direct in vitro protein-protein interactions. Using kinetics analyses, we observed that GlnD, Ugd, and MnmE activate FolC many-fold by decreasing the K half of FolC for its substrate l-glutamate. Moreover, FolC inhibited the GTPase activity of MnmE at low GTP concentrations. The growth phenotypes associated with these proteins are discussed. These results, obtained using direct in vitro enzyme assays, reveal unanticipated networks of allosteric regulatory interactions in the folate pathway in E. coli and indicate regulation of polyglutamylated tetrahydrofolate biosynthesis by the availability of nitrogen sources, signaled by the glutamine-sensing GlnD protein.
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Affiliation(s)
- Irina A Rodionova
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116,
| | - Norman Goodacre
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284, and
| | - Jimmy Do
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116
| | - Ali Hosseinnia
- Department of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Mohan Babu
- Department of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284, and
| | - Milton H Saier
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116,
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Competitive Growth Enhances Conditional Growth Mutant Sensitivity to Antibiotics and Exposes a Two-Component System as an Emerging Antibacterial Target in Burkholderia cenocepacia. Antimicrob Agents Chemother 2016; 61:AAC.00790-16. [PMID: 27799222 DOI: 10.1128/aac.00790-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 10/26/2016] [Indexed: 01/08/2023] Open
Abstract
Chemogenetic approaches to profile an antibiotic mode of action are based on detecting differential sensitivities of engineered bacterial strains in which the antibacterial target (usually encoded by an essential gene) or an associated process is regulated. We previously developed an essential-gene knockdown mutant library in the multidrug-resistant Burkholderia cenocepacia by transposon delivery of a rhamnose-inducible promoter. In this work, we used Illumina sequencing of multiplex-PCR-amplified transposon junctions to track individual mutants during pooled growth in the presence of antibiotics. We found that competition from nontarget mutants magnified the hypersensitivity of a clone underexpressing gyrB to novobiocin by 8-fold compared with hypersensitivity measured during clonal growth. Additional profiling of various antibiotics against a pilot library representing most categories of essential genes revealed a two-component system with unknown function, which, upon depletion of the response regulator, sensitized B. cenocepacia to novobiocin, ciprofloxacin, tetracycline, chloramphenicol, kanamycin, meropenem, and carbonyl cyanide 3-chlorophenylhydrazone, but not to colistin, hydrogen peroxide, and dimethyl sulfoxide. We named the gene cluster esaSR for enhanced sensitivity to antibiotics sensor and response regulator. Mutational analysis and efflux activity assays revealed that while esaS is not essential and is involved in antibiotic-induced efflux, esaR is an essential gene and regulates efflux independently of antibiotic-mediated induction. Furthermore, microscopic analysis of cells stained with propidium iodide provided evidence that depletion of EsaR has a profound effect on the integrity of cell membranes. In summary, we unraveled a previously uncharacterized two-component system that can be targeted to reduce antibiotic resistance in B. cenocepacia.
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28
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Mutations That Enhance the Ciprofloxacin Resistance of Escherichia coli with qnrA1. Antimicrob Agents Chemother 2015; 60:1537-45. [PMID: 26711751 DOI: 10.1128/aac.02167-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/13/2015] [Indexed: 01/20/2023] Open
Abstract
Plasmid-mediated qnr genes provide only a modest decrease in quinolone susceptibility but facilitate the selection of higher-level resistance. In Escherichia coli strain J53 without qnr, ciprofloxacin resistance often involves mutations in the GyrA subunit of DNA gyrase. Mutations in gyrA were absent, however, when 43 mutants with decreased ciprofloxacin susceptibility were selected from J53(pMG252) with qnrA1. Instead, in 13 mutants, individual and whole-genome sequencing identified mutations in marR and soxR associated with increased expression of marA and soxS and, through them, increased expression of the AcrAB pump, which effluxes quinolones. Nine mutants had increased expression of the MdtE efflux pump, and six demonstrated increased expression of the ydhE pump gene. Many efflux mutants also had increased resistance to novobiocin, another pump substrate, but other mutants were novobiocin hypersusceptible. Mutations in rfaD and rfaE in the pathway for inner core lipopolysaccharide (LPS) biosynthesis were identified in five such strains. Many of the pump and LPS mutants had decreased expression of OmpF, the major porin channel for ciprofloxacin entry. Three mutants had increased expression of qnrA that persisted when pMG252 from these strains was outcrossed. gyrA mutations were also rare when mutants with decreased ciprofloxacin susceptibility were selected from E. coli J53 with aac(6')-Ib-cr or qepA. We suggest that multiple genes conferring low-level resistance contribute to enhanced ciprofloxacin resistance selected from an E. coli strain carrying qnrA1, aac(6')-Ib-cr, or qepA because these determinants decrease the effective ciprofloxacin concentration and allow more common but lower-resistance mutations than those in gyrA to predominate.
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Sood S, Kaur S, Shrivastava R. A lacZ Reporter-Based Strategy for Rapid Expression Analysis and Target Validation of Mycobacterium tuberculosis Latent Infection Genes. Curr Microbiol 2015; 72:213-219. [PMID: 26597215 DOI: 10.1007/s00284-015-0942-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/01/2015] [Indexed: 11/25/2022]
Abstract
We report a novel lacZ fusion vector and demonstrate its utility for expression analysis of genes associated with Mycobacterium tuberculosis latent infection. The vector contains E. coli (oriE) and mycobacterial (oriM) origins of replication, a kanamycin resistance gene (Km(r)) as selection marker, and a lacZ reporter gene in fusion with MCS for cloning of upstream regulatory sequence of the desired genes. β-galactosidase activity of the vector was standardized for expression analysis under latent mycobacterial conditions using Phsp60, a constitutive mycobacterial promoter, utilizing Mycobacterium smegmatis as model organism. Validation of the vector was done by cloning and expression analysis of PhspX (alpha crystalline) and Picl (isocitrate lyase), promoters from two of the genes shown to be involved in M. tuberculosis persistence. Both genes showed appreciable levels of β-galactosidase expression under hypoxia-induced persistent conditions in comparison to their actively replicating state. Expression analysis of a set of hypothetical genes was also done, of which Rv0628c showed increased expression under persistent conditions. The reported fusion vector and the strategy can be effectively used for short listing and validation of drug targets deduced from various non-conclusive approaches such as bioinformatics and microarray analysis against latent/persistent form of mycobacterial infection.
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Affiliation(s)
- Shivani Sood
- Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh, 173234, India
| | - Satinder Kaur
- Division of Microbiology, Central Drug Research Institute, Lucknow, Uttar Pradesh, 226001, India
| | - Rahul Shrivastava
- Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh, 173234, India.
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30
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Multidrug Efflux Systems in Microaerobic and Anaerobic Bacteria. Antibiotics (Basel) 2015; 4:379-96. [PMID: 27025630 PMCID: PMC4790292 DOI: 10.3390/antibiotics4030379] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 08/11/2015] [Accepted: 08/13/2015] [Indexed: 12/13/2022] Open
Abstract
Active drug efflux constitutes an important mechanism of antibiotic and multidrug resistance in bacteria. Understanding the distribution, expression, and physiological functions of multidrug efflux pumps, especially under physiologically and clinically relevant conditions of the pathogens, is the key to combat drug resistance. In animal hosts, most wounded, infected and inflamed tissues display low oxygen tensions. In this article, we summarize research development on multidrug efflux pumps in the medicinally relevant microaerobic and anaerobic pathogens and their implications in the effort to combat drug-resistant infections.
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31
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Anes J, McCusker MP, Fanning S, Martins M. The ins and outs of RND efflux pumps in Escherichia coli. Front Microbiol 2015; 6:587. [PMID: 26113845 PMCID: PMC4462101 DOI: 10.3389/fmicb.2015.00587] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 05/28/2015] [Indexed: 11/13/2022] Open
Abstract
Infectious diseases remain one of the principal causes of morbidity and mortality in the world. Relevant authorities including the WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. They have also reaffirmed the urgent need for investment in the discovery and development of new antibiotics and therapeutic approaches to treat multidrug resistant (MDR) bacteria. The extensive use of antimicrobial compounds in diverse environments, including farming and healthcare, has been identified as one of the main causes for the emergence of MDR bacteria. Induced selective pressure has led bacteria to develop new strategies of defense against these chemicals. Bacteria can accomplish this by several mechanisms, including enzymatic inactivation of the target compound; decreased cell permeability; target protection and/or overproduction; altered target site/enzyme and increased efflux due to over-expression of efflux pumps. Efflux pumps can be specific for a single substrate or can confer resistance to multiple antimicrobials by facilitating the extrusion of a broad range of compounds including antibiotics, heavy metals, biocides and others, from the bacterial cell. To overcome antimicrobial resistance caused by active efflux, efforts are required to better understand the fundamentals of drug efflux mechanisms. There is also a need to elucidate how these mechanisms are regulated and how they respond upon exposure to antimicrobials. Understanding these will allow the development of combined therapies using efflux inhibitors together with antibiotics to act on Gram-negative bacteria, such as the emerging globally disseminated MDR pathogen Escherichia coli ST131 (O25:H4). This review will summarize the current knowledge on resistance-nodulation-cell division efflux mechanisms in E. coli, a bacteria responsible for community and hospital-acquired infections, as well as foodborne outbreaks worldwide.
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Affiliation(s)
- João Anes
- UCD Centre for Food Safety, School of Public Health, Physiotherapy and Population Science, UCD Centre for Molecular Innovation and Drug Discovery, University College Dublin Dublin, Ireland
| | - Matthew P McCusker
- UCD Centre for Food Safety, School of Public Health, Physiotherapy and Population Science, UCD Centre for Molecular Innovation and Drug Discovery, University College Dublin Dublin, Ireland
| | - Séamus Fanning
- UCD Centre for Food Safety, School of Public Health, Physiotherapy and Population Science, UCD Centre for Molecular Innovation and Drug Discovery, University College Dublin Dublin, Ireland
| | - Marta Martins
- UCD Centre for Food Safety, School of Public Health, Physiotherapy and Population Science, UCD Centre for Molecular Innovation and Drug Discovery, University College Dublin Dublin, Ireland
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32
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Li XZ, Plésiat P, Nikaido H. The challenge of efflux-mediated antibiotic resistance in Gram-negative bacteria. Clin Microbiol Rev 2015; 28:337-418. [PMID: 25788514 PMCID: PMC4402952 DOI: 10.1128/cmr.00117-14] [Citation(s) in RCA: 939] [Impact Index Per Article: 104.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.
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Affiliation(s)
- Xian-Zhi Li
- Human Safety Division, Veterinary Drugs Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Patrick Plésiat
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Centre Hospitalier Régional Universitaire, Université de Franche-Comté, Besançon, France
| | - Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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33
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Lin J, Nishino K, Roberts MC, Tolmasky M, Aminov RI, Zhang L. Mechanisms of antibiotic resistance. Front Microbiol 2015; 6:34. [PMID: 25699027 PMCID: PMC4318422 DOI: 10.3389/fmicb.2015.00034] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/11/2015] [Indexed: 12/22/2022] Open
Affiliation(s)
- Jun Lin
- Department of Animal Science, The University of Tennessee Knoxville, TN, USA
| | - Kunihiko Nishino
- Institute of Scientific and Industrial Research, Osaka University Osaka, Japan
| | - Marilyn C Roberts
- Department of Environmental and Occupational Health Sciences, University of Washington Seatle, WA, USA
| | - Marcelo Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, CA, USA
| | - Rustam I Aminov
- Section for Bacteriology, Pathology, and Parasitology, National Veterinary Institute, Technical University of Denmark Frederiksberg, Denmark
| | - Lixin Zhang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences Beijing, China
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34
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De Biase D, Lund PA. The Escherichia coli Acid Stress Response and Its Significance for Pathogenesis. ADVANCES IN APPLIED MICROBIOLOGY 2015; 92:49-88. [PMID: 26003933 DOI: 10.1016/bs.aambs.2015.03.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Escherichia coli has a remarkable ability to survive low pH and possesses a number of different genetic systems that enable it to do this. These may be expressed constitutively, typically in stationary phase, or induced by growth under a variety of conditions. The activities of these systems have been implicated in the ability of E. coli to pass the acidic barrier of the stomach and to become established in the gastrointestinal tract, something causing serious infections. However, much of the work characterizing these systems has been done on standard laboratory strains of E. coli and under conditions which do not closely resemble those found in the human gut. Here we review what is known about acid resistance in E. coli as a model laboratory organism and in the context of its lifestyle as an inhabitant-sometimes an unwelcome one-of the human gut.
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Lund P, Tramonti A, De Biase D. Coping with low pH: molecular strategies in neutralophilic bacteria. FEMS Microbiol Rev 2014; 38:1091-125. [PMID: 24898062 DOI: 10.1111/1574-6976.12076] [Citation(s) in RCA: 282] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 02/26/2014] [Accepted: 03/14/2014] [Indexed: 12/31/2022] Open
Abstract
As part of their life cycle, neutralophilic bacteria are often exposed to varying environmental stresses, among which fluctuations in pH are the most frequent. In particular, acid environments can be encountered in many situations from fermented food to the gastric compartment of the animal host. Herein, we review the current knowledge of the molecular mechanisms adopted by a range of Gram-positive and Gram-negative bacteria, mostly those affecting human health, for coping with acid stress. Because organic and inorganic acids have deleterious effects on the activity of the biological macromolecules to the point of significantly reducing growth and even threatening their viability, it is not unexpected that neutralophilic bacteria have evolved a number of different protective mechanisms, which provide them with an advantage in otherwise life-threatening conditions. The overall logic of these is to protect the cell from the deleterious effects of a harmful level of protons. Among the most favoured mechanisms are the pumping out of protons, production of ammonia and proton-consuming decarboxylation reactions, as well as modifications of the lipid content in the membrane. Several examples are provided to describe mechanisms adopted to sense the external acidic pH. Particular attention is paid to Escherichia coli extreme acid resistance mechanisms, the activity of which ensure survival and may be directly linked to virulence.
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Affiliation(s)
- Peter Lund
- School of Biosciences, University of Birmingham, Birmingham, UK
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36
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Sun J, Deng Z, Yan A. Bacterial multidrug efflux pumps: mechanisms, physiology and pharmacological exploitations. Biochem Biophys Res Commun 2014; 453:254-67. [PMID: 24878531 DOI: 10.1016/j.bbrc.2014.05.090] [Citation(s) in RCA: 443] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 05/20/2014] [Indexed: 01/11/2023]
Abstract
Multidrug resistance (MDR) refers to the capability of bacterial pathogens to withstand lethal doses of structurally diverse drugs which are capable of eradicating non-resistant strains. MDR has been identified as a major threat to the public health of human being by the World Health Organization (WHO). Among the four general mechanisms that cause antibiotic resistance including target alteration, drug inactivation, decreased permeability and increased efflux, drug extrusion by the multidrug efflux pumps serves as an important mechanism of MDR. Efflux pumps not only can expel a broad range of antibiotics owing to their poly-substrate specificity, but also drive the acquisition of additional resistance mechanisms by lowering intracellular antibiotic concentration and promoting mutation accumulation. Over-expression of multidrug efflux pumps have been increasingly found to be associated with clinically relevant drug resistance. On the other hand, accumulating evidence has suggested that efflux pumps also have physiological functions in bacteria and their expression is subject tight regulation in response to various of environmental and physiological signals. A comprehensive understanding of the mechanisms of drug extrusion, and regulation and physiological functions of efflux pumps is essential for the development of anti-resistance interventions. In this review, we summarize the development of these research areas in the recent decades and present the pharmacological exploitation of efflux pump inhibitors as a promising anti-drug resistance intervention.
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Affiliation(s)
- Jingjing Sun
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Ziqing Deng
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Aixin Yan
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
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