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Lobertti CA, Cabezudo I, Gizzi FO, Blancato V, Magni C, Furlán RLE, García Véscovi E. An allosteric inhibitor of the PhoQ histidine kinase with therapeutic potential against Salmonella infection. J Antimicrob Chemother 2024; 79:1820-1830. [PMID: 38853496 DOI: 10.1093/jac/dkae151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/30/2024] [Indexed: 06/11/2024] Open
Abstract
BACKGROUND The upsurge of antimicrobial resistance demands innovative strategies to fight bacterial infections. With traditional antibiotics becoming less effective, anti-virulence agents or pathoblockers, arise as an alternative approach that seeks to disarm pathogens without affecting their viability, thereby reducing selective pressure for the emergence of resistance mechanisms. OBJECTIVES To elucidate the mechanism of action of compound N'-(thiophen-2-ylmethylene)benzohydrazide (A16B1), a potent synthetic hydrazone inhibitor against the Salmonella PhoP/PhoQ system, essential for virulence. MATERIALS AND METHODS The measurement of the activity of PhoP/PhoQ-dependent and -independent reporter genes was used to evaluate the specificity of A16B1 to the PhoP regulon. Autokinase activity assays with either the native or truncated versions of PhoQ were used to dissect the A16B1 mechanism of action. The effect of A16B1 on Salmonella intramacrophage replication was assessed using the gentamicin protection assay. The checkerboard assay approach was used to analyse potentiation effects of colistin with the hydrazone. The Galleria mellonella infection model was chosen to evaluate A16B1 as an in vivo therapy against Salmonella. RESULTS A16B1 repressed the Salmonella PhoP/PhoQ system activity, specifically targeting PhoQ within the second transmembrane region. A16B1 demonstrates synergy with the antimicrobial peptide colistin, reduces the intramacrophage proliferation of Salmonella without being cytotoxic and enhances the survival of G. mellonella larvae systemically infected with Salmonella. CONCLUSIONS A16B1 selectively inhibits the activity of the Salmonella PhoP/PhoQ system through a novel inhibitory mechanism, representing a promising synthetic hydrazone compound with the potential to function as a Salmonella pathoblocker. This offers innovative prospects for combating Salmonella infections while mitigating the risk of antimicrobial resistance emergence.
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Affiliation(s)
- Carlos A Lobertti
- Instituto de Biología Molecular y Celular de Rosario Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Bioquímicas y Farmacéuticas, Departamento de Microbiología, Universidad Nacional de Rosario, Rosario S2000EZP, Argentina
| | - Ignacio Cabezudo
- Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario 2000, Argentina
| | - Fernán O Gizzi
- Instituto de Biología Molecular y Celular de Rosario Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Bioquímicas y Farmacéuticas, Departamento de Microbiología, Universidad Nacional de Rosario, Rosario S2000EZP, Argentina
| | - Víctor Blancato
- Instituto de Biología Molecular y Celular de Rosario Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Bioquímicas y Farmacéuticas, Departamento de Microbiología, Universidad Nacional de Rosario, Rosario S2000EZP, Argentina
| | - Christian Magni
- Instituto de Biología Molecular y Celular de Rosario Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Bioquímicas y Farmacéuticas, Departamento de Microbiología, Universidad Nacional de Rosario, Rosario S2000EZP, Argentina
| | - Ricardo L E Furlán
- Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario 2000, Argentina
| | - Eleonora García Véscovi
- Instituto de Biología Molecular y Celular de Rosario Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Bioquímicas y Farmacéuticas, Departamento de Microbiología, Universidad Nacional de Rosario, Rosario S2000EZP, Argentina
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Liu C, Zhang H, Peng X, Blackledge MS, Furlani RE, Li H, Su Z, Melander RJ, Melander C, Michalek S, Wu H. Small Molecule Attenuates Bacterial Virulence by Targeting Conserved Response Regulator. mBio 2023; 14:e0013723. [PMID: 37074183 PMCID: PMC10294662 DOI: 10.1128/mbio.00137-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 04/20/2023] Open
Abstract
Antibiotic tolerance within a biofilm community presents a serious public health challenge. Here, we report the identification of a 2-aminoimidazole derivative that inhibits biofilm formation by two pathogenic Gram-positive bacteria, Streptococcus mutans and Staphylococcus aureus. In S. mutans, the compound binds to VicR, a key response regulator, at the N-terminal receiver domain, and concurrently inhibits expression of vicR and VicR-regulated genes, including the genes that encode the key biofilm matrix producing enzymes, Gtfs. The compound inhibits S. aureus biofilm formation via binding to a Staphylococcal VicR homolog. In addition, the inhibitor effectively attenuates S. mutans virulence in a rat model of dental caries. As the compound targets bacterial biofilms and virulence through a conserved transcriptional factor, it represents a promising new class of anti-infective agents that can be explored to prevent or treat a host of bacterial infections. IMPORTANCE Antibiotic resistance is a major public health issue due to the growing lack of effective anti-infective therapeutics. New alternatives to treat and prevent biofilm-driven microbial infections, which exhibit high tolerance to clinically available antibiotics, are urgently needed. We report the identification of a small molecule that inhibits biofilm formation by two important pathogenic Gram-positive bacteria, Streptococcus mutans and Staphylococcus aureus. The small molecule selectively targets a transcriptional regulator leading to attenuation of a biofilm regulatory cascade and concurrent reduction of bacterial virulence in vivo. As the regulator is highly conserved, the finding has broad implication for the development of antivirulence therapeutics that selectively target biofilms.
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Affiliation(s)
- Chang Liu
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
| | - Hua Zhang
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Integrative Biomedical & Diagnostic Sciences, Oregon Health & Science University School of Dentistry, Portland, Oregon, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
| | - Xian Peng
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
| | - Meghan S. Blackledge
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Robert E. Furlani
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Haoting Li
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Zhaoming Su
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Suzanne Michalek
- Department of Integrative Biomedical & Diagnostic Sciences, Oregon Health & Science University School of Dentistry, Portland, Oregon, USA
| | - Hui Wu
- Department of Pediatric Dentistry, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
- Department of Integrative Biomedical & Diagnostic Sciences, Oregon Health & Science University School of Dentistry, Portland, Oregon, USA
- Department of Microbiology, University of Alabama at Birmingham Schools of Dentistry and Medicine, Birmingham, Alabama, USA
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Bhattarai S, Marsh L, Knight K, Ali L, Gomez A, Sunderhaus A, Abdel Aziz MH. NH125 Sensitizes Staphylococcus aureus to Cell Wall-Targeting Antibiotics through the Inhibition of the VraS Sensor Histidine Kinase. Microbiol Spectr 2023; 11:e0486122. [PMID: 37227302 PMCID: PMC10269531 DOI: 10.1128/spectrum.04861-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 05/09/2023] [Indexed: 05/26/2023] Open
Abstract
Staphylococcus aureus utilizes the two-component regulatory system VraSR to receive and relay environmental stress signals, and it is implicated in the development of bacterial resistance to several antibiotics through the upregulation of cell wall synthesis. VraS inhibition was shown to extend or restore the efficacy of several clinically used antibiotics. In this work, we study the enzymatic activity of the VraS intracellular domain (GST-VraS) to determine the kinetic parameters of the ATPase reaction and characterize the inhibition of NH125 under in vitro and microbiological settings. The rate of the autophosphorylation reaction was determined at different GST-VraS concentrations (0.95 to 9.49 μM) and temperatures (22 to 40°C) as well as in the presence of different divalent cations. The activity and inhibition by NH125, which is a known kinase inhibitor, were assessed in the presence and absence of the binding partner, VraR. The effects of inhibition on the bacterial growth kinetics and gene expression levels were determined. The GST-VraS rate of autophosphorylation increases with temperature and with the addition of VraR, with magnesium being the preferred divalent cation for the metal-ATP substrate complex. The mechanism of inhibition of NH125 was noncompetitive in nature and was attenuated in the presence of VraR. The addition of NH125 in the presence of sublethal doses of the cell wall-targeting antibiotics carbenicillin and vancomycin led to the complete abrogation of Staphylococcus aureus Newman strain growth and significantly decreased the gene expression levels of pbpB, blaZ, and vraSR in the presence of the antibiotics. IMPORTANCE This work characterizes the activity and inhibition of VraS, which is a key histidine kinase in a bacterial two-component system that is involved in Staphylococcus aureus antibiotic resistance. The results show the effect of temperature, divalent ions, and VraR on the activity and the kinetic parameters of ATP binding. The value of the KM of ATP is vital in designing screening assays to discover potent and effective VraS inhibitors with high translational potential. We report the ability of NH125 to inhibit VraS in vitro in a noncompetitive manner and investigate its effect on gene expression and bacterial growth kinetics in the presence and absence of cell wall-targeting antibiotics. NH125 effectively potentiated the effects of the antibiotics on bacterial growth and altered the expression of the genes that are regulated by VraS and are involved in mounting a resistance to antibiotics.
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Affiliation(s)
- Shrijan Bhattarai
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - Lane Marsh
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - Kelsey Knight
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - Liaqat Ali
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - Antonio Gomez
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - Allison Sunderhaus
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - May H. Abdel Aziz
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
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Alkatheri AH, Yap PSX, Abushelaibi A, Lai KS, Cheng WH, Erin Lim SH. Microbial Genomics: Innovative Targets and Mechanisms. Antibiotics (Basel) 2023; 12:190. [PMID: 36830101 PMCID: PMC9951906 DOI: 10.3390/antibiotics12020190] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Multidrug resistance (MDR) has become an increasing threat to global health because bacteria can develop resistance to antibiotics over time. Scientists worldwide are searching for new approaches that go beyond traditional antibiotic discovery and development pipelines. Advances in genomics, however, opened up an unexplored therapeutic opportunity for the discovery of new antibacterial agents. Genomic approaches have been used to discover several novel antibiotics that target critical processes for bacterial growth and survival, including histidine kinases (HKs), LpxC, FabI, peptide deformylase (PDF), and aminoacyl-tRNA synthetases (AaRS). In this review, we will discuss the use of microbial genomics in the search for innovative and promising drug targets as well as the mechanisms of action for novel antimicrobial agents. We will also discuss future directions on how the utilization of the microbial genomics approach could improve the odds of antibiotic development having a more successful outcome.
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Affiliation(s)
- Asma Hussain Alkatheri
- Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, Abu Dhabi 41012, United Arab Emirates
| | - Polly Soo-Xi Yap
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor 47500, Malaysia
| | - Aisha Abushelaibi
- Office of Campus Director, Abu Dhabi Colleges, Higher Colleges of Technology, Abu Dhabi 41012, United Arab Emirates
| | - Kok-Song Lai
- Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, Abu Dhabi 41012, United Arab Emirates
| | - Wan-Hee Cheng
- Faculty of Health and Life Sciences, INTI International University, Persiaran Perdana BBN, Nilai 71800, Malaysia
| | - Swee-Hua Erin Lim
- Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, Abu Dhabi 41012, United Arab Emirates
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Kong L, Su M, Sang J, Huang S, Wang M, Cai Y, Xie M, Wu J, Wang S, Foster SJ, Zhang J, Han A. The W-Acidic Motif of Histidine Kinase WalK Is Required for Signaling and Transcriptional Regulation in Streptococcus mutans. Front Microbiol 2022; 13:820089. [PMID: 35558126 PMCID: PMC9087282 DOI: 10.3389/fmicb.2022.820089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/14/2022] [Indexed: 02/05/2023] Open
Abstract
In Streptococcus mutans, we find that the histidine kinase WalK possesses the longest C-terminal tail (CTT) among all 14 TCSs, and this tail plays a key role in the interaction of WalK with its response regulator WalR. We demonstrate that the intrinsically disordered CTT is characterized by a conserved tryptophan residue surrounded by acidic amino acids. Mutation in the tryptophan not only disrupts the stable interaction, but also impairs the efficient phosphotransferase and phosphatase activities of WalRK. In addition, the tryptophan is important for WalK to compete with DNA containing a WalR binding motif for the WalR interaction. We further show that the tryptophan is important for in vivo transcriptional regulation and bacterial biofilm formation by S. mutans. Moreover, Staphylococcus aureus WalK also has a characteristic CTT, albeit relatively shorter, with a conserved W-acidic motif, that is required for the WalRK interaction in vitro. Together, these data reveal that the W-acidic motif of WalK is indispensable for its interaction with WalR, thereby playing a key role in the WalRK-dependent signal transduction, transcriptional regulation and biofilm formation.
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Affiliation(s)
- Lingyuan Kong
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Mingyang Su
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Jiayan Sang
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Shanshan Huang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Min Wang
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Yongfei Cai
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Mingquan Xie
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Jun Wu
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Shida Wang
- State Key Laboratory for Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Simon J Foster
- Department of Molecular Biology and Biotechnology, The Florey Institute, The University of Sheffield, Sheffield, United Kingdom
| | - Jiaqin Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Aidong Han
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
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uvrY deletion and acetate reduce gut colonization of Crohn's disease-associated adherent-invasive Escherichia coli by decreasing expression of type 1 fimbriae. Infect Immun 2022; 90:e0066221. [PMID: 34978926 DOI: 10.1128/iai.00662-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Adherent-invasive Escherichia coli (AIEC) is involved in onset and/or exacerbation of Crohn's disease. AIEC adapts to the gut environment by altering gene-expression programs, leading to successful gut-lumen colonization. However, the underlying mechanism of gut colonization is still far from clarified. Here, we show the role of UvrY, a response regulator of bacterial two-component signal transduction systems, in AIEC gut colonization. An AIEC mutant lacking the uvrY gene exhibited impairment of competitive colonization in the murine intestinal tract. UvrY contributes to functional expression of type 1 fimbriae by activating expression of small RNA CsrB, which confers adherence and invasion into epithelial cells on AIEC. In contrast, acetate suppresses the UvrY-dependent expression of type 1 fimbriae, resulting in less efficient cell invasion and attenuated gut colonization. Our findings might lead to therapeutic interventions for CD, in which inhibitions of UvrY activation and acetate supplementation reduce the colonization levels of AIEC by decreasing type-1 fimbriae expression.
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Progress Overview of Bacterial Two-Component Regulatory Systems as Potential Targets for Antimicrobial Chemotherapy. Antibiotics (Basel) 2020; 9:antibiotics9100635. [PMID: 32977461 PMCID: PMC7598275 DOI: 10.3390/antibiotics9100635] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 12/18/2022] Open
Abstract
Bacteria adapt to changes in their environment using a mechanism known as the two-component regulatory system (TCS) (also called “two-component signal transduction system” or “two-component system”). It comprises a pair of at least two proteins, namely the sensor kinase and the response regulator. The former senses external stimuli while the latter alters the expression profile of bacterial genes for survival and adaptation. Although the first TCS was discovered and characterized in a non-pathogenic laboratory strain of Escherichia coli, it has been recognized that all bacteria, including pathogens, use this mechanism. Some TCSs are essential for cell growth and fitness, while others are associated with the induction of virulence and drug resistance/tolerance. Therefore, the TCS is proposed as a potential target for antimicrobial chemotherapy. This concept is based on the inhibition of bacterial growth with the substances acting like conventional antibiotics in some cases. Alternatively, TCS targeting may reduce the burden of bacterial virulence and drug resistance/tolerance, without causing cell death. Therefore, this approach may aid in the development of antimicrobial therapeutic strategies for refractory infections caused by multi-drug resistant (MDR) pathogens. Herein, we review the progress of TCS inhibitors based on natural and synthetic compounds.
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Thielen MK, Vaneerd CK, Goswami M, Carlson EE, May JF. 2-Aminobenzothiazoles Inhibit Virulence Gene Expression and Block Polymyxin Resistance in Salmonella enterica. Chembiochem 2020; 21:3500-3503. [PMID: 32750193 DOI: 10.1002/cbic.202000422] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/30/2020] [Indexed: 01/01/2023]
Abstract
One promising strategy to combat antibiotic-resistant bacteria is to develop compounds that block bacterial defenses against antibacterial conditions produced by the innate immune system. Salmonella enterica, which causes food-borne gastroenteritis and typhoid fever, requires histidine kinases (HKs) to resist innate immune defenses such as cationic antimicrobial peptides (CAMPs). Herein, we report that 2-aminobenzothiazoles block histidine kinase-dependent phenotypes in Salmonella enterica serotype Typhimurium. We found that 2-aminobenzothiazoles inhibited growth under low Mg2+ , a stressful condition that requires histidine kinase-mediated responses, and decreased expression of the virulence genes pagC and pagK. Furthermore, we discovered that 2-aminobenzothiazoles weaken Salmonella's resistance to polymyxin B and polymyxin E, which are last-line antibiotics and models for host defense CAMPs. These findings raise the possibilities that 2-aminobenzothiazoles can block HK-mediated bacterial defenses and can be used in combination with polymyxins to treat infections caused by Salmonella.
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Affiliation(s)
- Michaela K Thielen
- Department of Chemistry and Biochemistry, University of Wisconsin-La Crosse, 1725 State St, La Crosse, WI 54601, USA
| | - Cody K Vaneerd
- Department of Chemistry and Biochemistry, University of Wisconsin-La Crosse, 1725 State St, La Crosse, WI 54601, USA
| | - Manibarsha Goswami
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Erin E Carlson
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - John F May
- Department of Chemistry and Biochemistry, University of Wisconsin-La Crosse, 1725 State St, La Crosse, WI 54601, USA
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Asif M, Imran M. Quorum Sensing Inhibition: Current Advances of the Natural Antimicrobial Agents. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2020. [DOI: 10.1134/s1068162019060049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Quinazoline-Based Antivirulence Compounds Selectively Target Salmonella PhoP/PhoQ Signal Transduction System. Antimicrob Agents Chemother 2019; 64:AAC.01744-19. [PMID: 31611347 DOI: 10.1128/aac.01744-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 09/27/2019] [Indexed: 01/06/2023] Open
Abstract
The rapid emergence of multidrug resistance among bacterial pathogens has become a significant challenge to human health in our century. Therefore, development of next-generation antibacterial compounds is an urgent need. Two-component signal transduction systems (TCS) are stimulus-response coupling devices that allow bacteria to sense and elaborate adaptive responses to changing environmental conditions, including the challenges that pathogenic bacteria face inside the host. The differential presence of TCS, present in bacteria but absent in the animal kingdom, makes them attractive targets in the search for new antibacterial compounds. In Salmonella enterica, the PhoP/PhoQ two-component system controls the expression of crucial phenotypes that define the ability of the pathogen to establish infection in the host. We now report the screening of 686 compounds from a GlaxoSmithKline published kinase inhibitor set in a high-throughput whole-cell assay that targets Salmonella enterica serovar Typhimurium PhoP/PhoQ. We identified a series of quinazoline compounds that showed selective and potent downregulation of PhoP/PhoQ-activated genes and define structural attributes required for their efficacy. We demonstrate that their bioactivity is due to repression of the PhoQ sensor autokinase activity mediated by interaction with its catalytic domain, acting as competitive inhibitors of ATP binding. While noncytotoxic, the hit molecules exhibit antivirulence effect by blockage of S Typhimurium intramacrophage replication. Together, these features make these quinazoline compounds stand out as exciting leads to develop a therapeutic intervention to fight salmonellosis.
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Bai J, Zhu X, Zhao K, Yan Y, Xu T, Wang J, Zheng J, Huang W, Shi L, Shang Y, Lv Z, Wang X, Wu Y, Qu D. The role of ArlRS in regulating oxacillin susceptibility in methicillin-resistant Staphylococcus aureus indicates it is a potential target for antimicrobial resistance breakers. Emerg Microbes Infect 2019; 8:503-515. [PMID: 30924407 PMCID: PMC6455253 DOI: 10.1080/22221751.2019.1595984] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA), also known as oxacillin-resistant S. aureus, is a leading cause of community and hospital associated infections globally. In this work, we found that deletion of the arlRS two-component system genes in the USA300 and USA500 strains resulted in increased susceptibilities to oxacillin (8–16-fold decrease in minimal inhibitory concentrations). In USA300ΔarlRS, transcriptional levels of mecA or blaZ showed no obvious change, while mRNA levels of spx showed a 4-fold decrease at 4 h and a 6.3-fold decrease at 10 h. Overexpression of spx in ΔarlRS restored oxacillin resistance to a similar level in USA300. In addition, gel shift assay showed that the recombinant ArlR bound to spx promoter region. Furthermore, silencing of spx led to a significant increase of oxacillin susceptibility in multiple MRSA isolates. Our results indicate that ArlRS plays a strong role in regulating oxacillin resistance in MRSA strains, which involves direct modulation of spx expression. Moreover, oritavancin showed inhibition to ATPase activity of the recombinant histidine kinase ArlS (IC50 = 5.47 μM). Oritavancin had synergy effect on oxacillin activity against the MRSA strains in both planktonic and biofilm state. Our data suggest that ArlRS is an attractive target for breaking antimicrobial resistance of MRSA.
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Affiliation(s)
- Jinna Bai
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Xiaoyi Zhu
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Keqing Zhao
- b Department of Otorhinolaryngology-Head and Neck Surgery, Eye & ENT Hospital, Shanghai Key Clinical Disciplines of otorhinolaryngology , Fudan University , Shanghai , People's Republic of China
| | - Yingjie Yan
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Tao Xu
- c Key Laboratory of Medical Molecular Virology , Huashan Hospital, Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Jiaxue Wang
- d Department of Laboratory Medicine , Hangzhou Medical College , Hangzhou , Zhejiang , People's Republic of China
| | - Jinxing Zheng
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China.,e Department of Infectious Diseases and the Key Laboratory of Endogenous Infection , Shenzhen Nanshan People's Hospital of Shenzhen University , Shenzhen , People's Republic of China
| | - Wei Huang
- f Medical Clinic, Hangzhou Haiqin Sanatorium , Hangzhou , Zhejiang , People's Republic of China
| | - Le Shi
- b Department of Otorhinolaryngology-Head and Neck Surgery, Eye & ENT Hospital, Shanghai Key Clinical Disciplines of otorhinolaryngology , Fudan University , Shanghai , People's Republic of China
| | - Yongpeng Shang
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Zhihui Lv
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Xiaofei Wang
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Yang Wu
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
| | - Di Qu
- a Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences , Shanghai Medical College of Fudan University , Shanghai , People's Republic of China
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Tierney AR, Rather PN. Roles of two-component regulatory systems in antibiotic resistance. Future Microbiol 2019; 14:533-552. [PMID: 31066586 DOI: 10.2217/fmb-2019-0002] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Two-component regulatory systems (TCSs) are a major mechanism by which bacteria sense and respond to changes in their environment. TCSs typically consist of two proteins that bring about major regulation of the cell genome through coordinated action mediated by phosphorylation. Environmental conditions that activate TCSs are numerous and diverse and include exposure to antibiotics as well as conditions inside a host. The resulting regulatory action often involves activation of antibiotic defenses and changes to cell physiology that increase antibiotic resistance. Examples of resistance mechanisms enacted by TCSs contained in this review span those found in both Gram-negative and Gram-positive species and include cell surface modifications, changes in cell permeability, increased biofilm formation, and upregulation of antibiotic-degrading enzymes.
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Affiliation(s)
- Aimee Rp Tierney
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, 30322 USA
| | - Philip N Rather
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, 30322 USA.,Research Service, Department of Veterans' Affairs, Atlanta VA Health Care System, Decatur, GA, 30033 USA
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13
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De Silva PM, Kumar A. Signal Transduction Proteins in Acinetobacter baumannii: Role in Antibiotic Resistance, Virulence, and Potential as Drug Targets. Front Microbiol 2019; 10:49. [PMID: 30761101 PMCID: PMC6363711 DOI: 10.3389/fmicb.2019.00049] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/14/2019] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a notorious pathogen in health care settings around the world, primarily due to high resistance to antibiotics. A. baumannii also shows an impressive capability to adapt to harsh conditions in clinical settings, which contributes to its persistence in such conditions. Following their traditional role, the Two Component Systems (TCSs) present in A. baumannii play a crucial role in sensing and adapting to the changing environmental conditions. This provides A. baumannii with a greater chance of survival even in unfavorable conditions. Since all the TCSs characterized to date in A. baumannii play a role in its antibiotic resistance and virulence, understanding the underlying molecular mechanisms behind TCSs can help with a better understanding of the pathways that regulate these phenotypes. This can also guide efforts to target TCSs as novel drug targets. In this review, we discuss the roles of TCSs in A. baumannii, their molecular mechanisms, and most importantly, the potential of using small molecule inhibitors of TCSs as potential novel drug targets.
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Affiliation(s)
- P Malaka De Silva
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada.,Manitoba Chemosensory Biology Group, University of Manitoba, Winnipeg, MB, Canada
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14
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Ahmad S, Shaker B, Ahmad F, Raza S, Azam SS. Moleculer dynamics simulaiton revealed reciever domain of Acinetobacter baumannii BfmR enzyme as the hot spot for future antibiotics designing. J Biomol Struct Dyn 2018; 37:2897-2912. [DOI: 10.1080/07391102.2018.1498805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Sajjad Ahmad
- Computational Biology Lab, National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan
| | - Bilal Shaker
- Computational Biology Lab, National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan
| | - Faisal Ahmad
- Computational Biology Lab, National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan
| | - Saad Raza
- Computational Biology Lab, National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan
| | - Syed Sikander Azam
- Computational Biology Lab, National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan
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15
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Muller C, Massier S, Le Breton Y, Rincé A. The role of the CroR response regulator in resistance of Enterococcus faecalis to D-cycloserine is defined using an inducible receiver domain. Mol Microbiol 2017; 107:416-427. [PMID: 29205552 DOI: 10.1111/mmi.13891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/28/2017] [Accepted: 12/01/2017] [Indexed: 11/28/2022]
Abstract
Enterococcus faecalis is an opportunistic multidrug-resistant human pathogen causing severe nosocomial infections. Previous investigations revealed that the CroRS two-component regulatory pathway likely displays a pleiotropic role in E. faecalis, involved in virulence, macrophage survival, oxidative stress response as well as antibiotic resistance. Therefore, CroRS represents an attractive potential new target for antibiotherapy. In this report, we further explored CroRS cellular functions by characterizing the CroR regulon: the 'domain swapping' method was applied and a CroR chimera protein was generated by fusing the receiver domain from NisR to the output domain from CroR. After demonstrating that the chimera CroR complements a croR gene deletion in E. faecalis (stress response, virulence), we conducted a global gene expression analysis using RNA-Seq and identified 50 potential CroR targets involved in multiple cellular functions such as cell envelope homeostasis, substrate transport, cell metabolism, gene expression regulation, stress response, virulence and antibiotic resistance. For validation, CroR direct binding to several candidate targets was demonstrated by EMSA. Further, this work identified alr, the gene encoding the alanine racemase enzyme involved in E. faecalis resistance to D-cycloserine, a promising antimicrobial drug to treat enterococcal infections, as a member of the CroR regulon.
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Affiliation(s)
- Cécile Muller
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
| | - Sébastien Massier
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
| | - Yoann Le Breton
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
| | - Alain Rincé
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
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16
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Cardona ST, Choy M, Hogan AM. Essential Two-Component Systems Regulating Cell Envelope Functions: Opportunities for Novel Antibiotic Therapies. J Membr Biol 2017; 251:75-89. [DOI: 10.1007/s00232-017-9995-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 10/20/2017] [Indexed: 01/22/2023]
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17
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Utsumi R. Bacterial signal transduction networks via connectors and development of the inhibitors as alternative antibiotics. Biosci Biotechnol Biochem 2017; 81:1663-1669. [PMID: 28743208 DOI: 10.1080/09168451.2017.1350565] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bacterial cells possess a signal transduction system that differs from those described in higher organisms, including human cells. These so-called two-component signal transduction systems (TCSs) consist of a sensor (histidine kinase, HK) and a response regulator, and are involved in cellular functions, such as virulence, drug resistance, biofilm formation, cell wall synthesis, cell division. They are conserved in bacteria across all species. Although TCSs are often studied and characterized individually, they are assumed to interact with each other and form signal transduction networks within the cell. In this review, I focus on the formation of TCS networks via connectors. I also explore the possibility of using TCS inhibitors, especially HK inhibitors, as alternative antimicrobial agents.
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Affiliation(s)
- Ryutaro Utsumi
- a Department of Bioscience, Graduate School of Agriculture , Kindai University , Nara , Japan
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18
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Draughn GL, Allen CL, Routh PA, Stone MR, Kirker KR, Boegli L, Schuchman RM, Linder KE, Baynes RE, James G, Melander C, Pollard A, Cavanagh J. Evaluation of a 2-aminoimidazole variant as adjuvant treatment for dermal bacterial infections. DRUG DESIGN DEVELOPMENT AND THERAPY 2017; 11:153-162. [PMID: 28138218 PMCID: PMC5241126 DOI: 10.2147/dddt.s111865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
2-Aminoimidazole (2-AI)-based compounds have been shown to efficiently disrupt biofilm formation, disperse existing biofilms, and resensitize numerous multidrug-resistant bacteria to antibiotics. Using Pseudomonas aeruginosa and Staphylococcus aureus, we provide initial pharmacological studies regarding the application of a 2-AI as a topical adjuvant for persistent dermal infections. In vitro assays indicated that the 2-AI H10 is nonbactericidal, resensitizes bacteria to antibiotics, does not harm the integument, and promotes wound healing. Furthermore, in vivo application of H10 on swine skin caused no gross abnormalities or immune reactions. Taken together, these results indicate that H10 represents a promising lead dermal adjuvant compound.
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Affiliation(s)
| | | | - Patricia A Routh
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Maria R Stone
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Kelly R Kirker
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | - Laura Boegli
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | | | - Keith E Linder
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Ronald E Baynes
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Garth James
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | - Christian Melander
- Department of Chemistry, North Carolina State University, Raleigh, NC, USA
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19
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Deng DM, Liu MJ, ten Cate JM, Crielaard W. The VicRK System of Streptococcus mutans Responds to Oxidative Stress. J Dent Res 2016; 86:606-10. [PMID: 17586705 DOI: 10.1177/154405910708600705] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In Streptococcus mutans, virulence and cariogenicity may be modulated via the two-component regulatory system VicRK. Environmental signals, sensed by VicK, inducing this modulation are still unclear, however, and were investigated in the present study. We found that VicRK displays homology with protein-domains that, in other bacteria, are involved in redox-sensing. After constructing a VicRK-promoter GFP-reporter strain, we showed increased fluorescence intensity under oxidative stress. Potential interference of alternative signals and experimental conditions on GFP expression was excluded by the use of negative and positive control strains. Finally, we constructed a clean vicK knockout mutant, which proved to be more sensitive to H2O2 than the wild-type. In conclusion, this study showed that the VicRK system responds to and protects against oxidative stress. As a result, a link between oxidative/redox stress and the cariogenic nature of S. mutans can be hypothesized.
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Affiliation(s)
- D M Deng
- Department of Cariology, Academic Centre for Dentistry Amsterdam ACTA, Amsterdam, The Netherlands.
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20
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The Response Regulator BfmR Is a Potential Drug Target for Acinetobacter baumannii. mSphere 2016; 1:mSphere00082-16. [PMID: 27303741 PMCID: PMC4888885 DOI: 10.1128/msphere.00082-16] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 04/12/2016] [Indexed: 11/24/2022] Open
Abstract
Increasing antibiotic resistance in bacteria, particularly Gram-negative bacilli, has significantly affected the ability of physicians to treat infections, with resultant increased morbidity, mortality, and health care costs. In fact, some strains of bacteria are resistant to all available antibiotics, such as Acinetobacter baumannii, which is the focus of this report. Therefore, the development of new antibiotics active against these resistant strains is urgently needed. In this study, BfmR is further validated as an intriguing target for a novel class of antibiotics. Successful inactivation of BfmR would confer the multiple benefits of a decreased ability of A. baumannii to survive in human body fluids, increased sensitivity to complement-mediated bactericidal activity and, importantly, increased sensitivity to other antibiotics. Structural studies support the potential for this “druggable” target, as they identify the potential for small-molecule binding at functionally relevant sites. Next-phase high-throughput screening studies utilizing BfmR are warranted. Identification and validation is the first phase of target-based antimicrobial development. BfmR (RstA), a response regulator in a two-component signal transduction system (TCS) in Acinetobacter baumannii, is an intriguing potential antimicrobial target. A unique characteristic of BfmR is that its inhibition would have the dual benefit of significantly decreasing in vivo survival and increasing sensitivity to selected antimicrobials. Studies on the clinically relevant strain AB307-0294 have shown BfmR to be essential in vivo. Here, we demonstrate that this phenotype in strains AB307-0294 and AB908 is mediated, in part, by enabling growth in human ascites fluid and serum. Further, BfmR conferred resistance to complement-mediated bactericidal activity that was independent of capsular polysaccharide. Importantly, BfmR also increased resistance to the clinically important antimicrobials meropenem and colistin. BfmR was highly conserved among A. baumannii strains. The crystal structure of the receiver domain of BfmR was determined, lending insight into putative ligand binding sites. This enabled an in silico ligand binding analysis and a blind docking strategy to assess use as a potential druggable target. Predicted binding hot spots exist at the homodimer interface and the phosphorylation site. These data support pursuing the next step in the development process, which includes determining the degree of inhibition needed to impact growth/survival and the development a BfmR activity assay amenable to high-throughput screening for the identification of inhibitors. Such agents would represent a new class of antimicrobials active against A. baumannii which could be active against other Gram-negative bacilli that possess a TCS with shared homology. IMPORTANCE Increasing antibiotic resistance in bacteria, particularly Gram-negative bacilli, has significantly affected the ability of physicians to treat infections, with resultant increased morbidity, mortality, and health care costs. In fact, some strains of bacteria are resistant to all available antibiotics, such as Acinetobacter baumannii, which is the focus of this report. Therefore, the development of new antibiotics active against these resistant strains is urgently needed. In this study, BfmR is further validated as an intriguing target for a novel class of antibiotics. Successful inactivation of BfmR would confer the multiple benefits of a decreased ability of A. baumannii to survive in human body fluids, increased sensitivity to complement-mediated bactericidal activity and, importantly, increased sensitivity to other antibiotics. Structural studies support the potential for this “druggable” target, as they identify the potential for small-molecule binding at functionally relevant sites. Next-phase high-throughput screening studies utilizing BfmR are warranted.
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21
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Feldmann EA, Cavanagh J. Teaching old drugs new tricks: Addressing resistance in Francisella. Virulence 2016; 6:414-6. [PMID: 26055396 DOI: 10.1080/21505594.2015.1053689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Erik A Feldmann
- a Department of Molecular and Structural Biochemistry; North Carolina State University ; Raleigh , NC , USA
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22
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Listeria monocytogenes – An examination of food chain factors potentially contributing to antimicrobial resistance. Food Microbiol 2016. [DOI: 10.1016/j.fm.2014.08.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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23
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Kang J, Wiedmann M, Boor KJ, Bergholz TM. VirR-Mediated Resistance of Listeria monocytogenes against Food Antimicrobials and Cross-Protection Induced by Exposure to Organic Acid Salts. Appl Environ Microbiol 2015; 81:4553-62. [PMID: 25911485 PMCID: PMC4475887 DOI: 10.1128/aem.00648-15] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/21/2015] [Indexed: 12/17/2022] Open
Abstract
Formulations of ready-to-eat (RTE) foods with antimicrobial compounds constitute an important safety measure against foodborne pathogens such as Listeria monocytogenes. While the efficacy of many commercially available antimicrobial compounds has been demonstrated in a variety of foods, the current understanding of the resistance mechanisms employed by L. monocytogenes to counteract these stresses is limited. In this study, we screened in-frame deletion mutants of two-component system response regulators associated with the cell envelope stress response for increased sensitivity to commercially available antimicrobial compounds (nisin, lauric arginate, ε-polylysine, and chitosan). A virR deletion mutant showed increased sensitivity to all antimicrobials and significantly greater loss of membrane integrity when exposed to nisin, lauric arginate, or ε-polylysine (P < 0.05). The VirR-regulated operon, dltABCD, was shown to be the key contributor to resistance against these antimicrobial compounds, whereas another VirR-regulated gene, mprF, displayed an antimicrobial-specific contribution to resistance. An experiment with a β-glucuronidase (GUS) reporter fusion with the dlt promoter indicated that nisin does not specifically induce VirR-dependent upregulation of dltABCD. Lastly, prior exposure of L. monocytogenes parent strain H7858 and the ΔvirR mutant to 2% potassium lactate enhanced subsequent resistance against nisin and ε-polylysine (P < 0.05). These data demonstrate that VirRS-mediated regulation of dltABCD is the major resistance mechanism used by L. monocytogenes against cell envelope-damaging food antimicrobials. Further, the potential for cross-protection induced by other food-related stresses (e.g., organic acids) needs to be considered when applying these novel food antimicrobials as a hurdle strategy for RTE foods.
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Affiliation(s)
- Jihun Kang
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Kathryn J Boor
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Teresa M Bergholz
- Department of Food Science, Cornell University, Ithaca, New York, USA Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, North Dakota, USA
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24
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DevR (DosR) mimetic peptides impair transcriptional regulation and survival of Mycobacterium tuberculosis under hypoxia by inhibiting the autokinase activity of DevS sensor kinase. BMC Microbiol 2014; 14:195. [PMID: 25048654 PMCID: PMC4110071 DOI: 10.1186/1471-2180-14-195] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 07/11/2014] [Indexed: 01/06/2023] Open
Abstract
Background Two-component systems have emerged as compelling targets for antibacterial drug design for a number of reasons including the distinct histidine phosphorylation property of their constituent sensor kinases. The DevR-DevS/DosT two component system of Mycobacterium tuberculosis (M. tb) is essential for survival under hypoxia, a stress associated with dormancy development in vivo. In the present study a combinatorial peptide phage display library was screened for DevS histidine kinase interacting peptides with the aim of isolating inhibitors of DevR-DevS signaling. Results DevS binding peptides were identified from a phage display library after three rounds of panning using DevS as bait. The peptides showed sequence similarity with conserved residues in the N-terminal domain of DevR and suggested that they may represent interacting surfaces between DevS and DevR. Two DevR mimetic peptides were found to specifically inhibit DevR-dependent transcriptional activity and restrict the hypoxic survival of M. tb. The mechanism of peptide action is majorly attributed to an inhibition of DevS autokinase activity. Conclusions These findings demonstrate that DevR mimetic peptides impede DevS activation and that intercepting DevS activation at an early step in the signaling cascade impairs M. tb survival in a hypoxia persistence model.
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25
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Role of the PAS sensor domains in the Bacillus subtilis sporulation kinase KinA. J Bacteriol 2013; 195:2349-58. [PMID: 23504013 DOI: 10.1128/jb.00096-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Histidine kinases are sophisticated molecular sensors that are used by bacteria to detect and respond to a multitude of environmental signals. KinA is the major histidine kinase required for initiation of sporulation upon nutrient deprivation in Bacillus subtilis. KinA has a large N-terminal region (residues 1 to 382) that is uniquely composed of three tandem Per-ARNT-Sim (PAS) domains that have been proposed to constitute a sensor module. To further enhance our understanding of this "sensor" region, we defined the boundaries that give rise to the minimal autonomously folded PAS domains and analyzed their homo- and heteroassociation properties using analytical ultracentrifugation, nuclear magnetic resonance (NMR) spectroscopy, and multiangle laser light scattering. We show that PAS(A) self-associates very weakly, while PAS(C) is primarily a monomer. In contrast, PAS(B) forms a stable dimer (K(d) [dissociation constant] of <10 nM), and it appears to be the main N-terminal determinant of KinA dimerization. Analysis of KinA mutants deficient for one or more PAS domains revealed a critical role for PAS(B), but not PAS(A), in autophosphorylation of KinA. Our findings suggest that dimerization of PAS(B) is important for keeping the catalytic domain of KinA in a functional conformation. We use this information to propose a model for the structure of the N-terminal sensor module of KinA.
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26
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Commichau FM, Pietack N, Stülke J. Essential genes in Bacillus subtilis: a re-evaluation after ten years. MOLECULAR BIOSYSTEMS 2013; 9:1068-75. [PMID: 23420519 DOI: 10.1039/c3mb25595f] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In 2003, an initial study on essential genes in the Gram-positive model bacterium described 271 genes as essential. In the past decade, the functions of many unknown genes and their encoded proteins have been elucidated. Moreover, detailed analyses have revealed that 31 genes that were thought to be essential are in fact non-essential whereas 20 novel essential genes have been described. Thus, 261 genes coding for 259 proteins and two functional RNAs are regarded essential as of January 2013. Among the essential proteins, the largest group is involved in protein synthesis, secretion and protein quality control. Other large sets of essential proteins are involved in lipid biosynthesis, cell wall metabolism and cell division, and DNA replication. Another interesting group of essential proteins protects the cell against endogenous toxic proteins, metabolites, or other intermediates. There are only six essential proteins in B. subtilis, for which no function is known. The functional analysis of these important proteins is predicted to be a key issue in the research on this model organism in the coming years.
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Affiliation(s)
- Fabian M Commichau
- Department of General Microbiology, Georg-August-Universität Göttingen, Grisebachstr. 8, 37077 Göttingen, Germany
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27
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Thompson RJ, Bobay BG, Stowe SD, Olson AL, Peng L, Su Z, Actis LA, Melander C, Cavanagh J. Identification of BfmR, a response regulator involved in biofilm development, as a target for a 2-Aminoimidazole-based antibiofilm agent. Biochemistry 2012. [PMID: 23186243 DOI: 10.1021/bi3015289] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2-Aminoimidazoles (2AIs) have been documented to disrupt bacterial protection mechanisms, including biofilm formation and genetically encoded antibiotic resistance traits. Using Acinetobacter baumannii, we provide initial insight into the mechanism of action of a 2AI-based antibiofilm agent. Confocal microscopy confirmed that the 2AI is cell permeable, while pull-down assays identified BfmR, a response regulator that is the master controller of biofilm formation, as a target for this compound. Binding assays demonstrated specificity of the 2AI for response regulators, while computational docking provided models for 2AI-BfmR interactions. The 2AI compound studied here represents a unique small molecule scaffold that targets bacterial response regulators.
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Affiliation(s)
- Richele J Thompson
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
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28
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Ng WL, Perez L, Cong J, Semmelhack MF, Bassler BL. Broad spectrum pro-quorum-sensing molecules as inhibitors of virulence in vibrios. PLoS Pathog 2012; 8:e1002767. [PMID: 22761573 PMCID: PMC3386246 DOI: 10.1371/journal.ppat.1002767] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 05/07/2012] [Indexed: 01/30/2023] Open
Abstract
Quorum sensing (QS) is a bacterial cell-cell communication process that relies on the production and detection of extracellular signal molecules called autoinducers. QS allows bacteria to perform collective activities. Vibrio cholerae, a pathogen that causes an acute disease, uses QS to repress virulence factor production and biofilm formation. Thus, molecules that activate QS in V. cholerae have the potential to control pathogenicity in this globally important bacterium. Using a whole-cell high-throughput screen, we identified eleven molecules that activate V. cholerae QS: eight molecules are receptor agonists and three molecules are antagonists of LuxO, the central NtrC-type response regulator that controls the global V. cholerae QS cascade. The LuxO inhibitors act by an uncompetitive mechanism by binding to the pre-formed LuxO-ATP complex to inhibit ATP hydrolysis. Genetic analyses suggest that the inhibitors bind in close proximity to the Walker B motif. The inhibitors display broad-spectrum capability in activation of QS in Vibrio species that employ LuxO. To the best of our knowledge, these are the first molecules identified that inhibit the ATPase activity of a NtrC-type response regulator. Our discovery supports the idea that exploiting pro-QS molecules is a promising strategy for the development of novel anti-infectives.
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Affiliation(s)
- Wai-Leung Ng
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
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29
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Decreased expression of type 1 fimbriae by a pst mutant of uropathogenic Escherichia coli reduces urinary tract infection. Infect Immun 2012; 80:2802-15. [PMID: 22665376 DOI: 10.1128/iai.00162-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pstSCAB-phoU operon encodes the phosphate-specific transport system (Pst). Loss of Pst constitutively activates the Pho regulon and decreases bacterial virulence. However, specific mechanisms underlying decreased bacterial virulence through inactivation of Pst are poorly understood. In uropathogenic Escherichia coli (UPEC) strain CFT073, inactivation of pst decreased urinary tract colonization in CBA/J mice. The pst mutant was deficient in production of type 1 fimbriae and showed decreased expression of the fimA structural gene which correlated with differential expression of the fimB, fimE, ipuA, and ipbA genes, encoding recombinases, mediating inversion of the fim promoter. The role of fim downregulation in attenuation of the pst mutant was confirmed using a fim phase-locked-on derivative, which demonstrated a significant gain in virulence. In addition, the pst mutant was less able to invade human bladder epithelial cells. Since type 1 fimbriae contribute to UPEC virulence by promoting colonization and invasion of bladder cells, the reduced bladder colonization by the pst mutant is predominantly attributed to downregulation of these fimbriae. Elucidation of mechanisms mediating the control of type 1 fimbriae through activation of the Pho regulon in UPEC may open new avenues for therapeutics or prophylactics against urinary tract infections.
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30
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Isolation and characterization of signermycin B, an antibiotic that targets the dimerization domain of histidine kinase WalK. Antimicrob Agents Chemother 2012; 56:3657-63. [PMID: 22526318 DOI: 10.1128/aac.06467-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The WalK (histidine kinase)/WalR (response regulator) two-component signal transduction system is a master regulatory system for cell wall metabolism and growth. This system is conserved in low G+C Gram-positive bacteria, including Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, and Streptococcus mutans. In this study, we found the first antibiotic that functions as a WalK inhibitor (signermycin B) by screening 10,000 Streptomyces extracts. The chemical structure (C(23)H(35)NO(4); molecular weight, 389.5) comprises a tetramic acid moiety and a decalin ring. Signermycin B exhibited antimicrobial activity, with MIC values ranging from 3.13 μg/ml (8 μM) to 6.25 μg/ml (16 μM) against Gram-positive bacteria that possess the WalK/WalR two-component signal transduction system, including the drug-resistant bacteria methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis. The half-maximal inhibitory concentrations of signermycin B against WalK in these organisms ranged from 37 to 61 μM. To determine the mechanism of action of signermycin B, surface plasmon resonance response analysis with the two WalK domains of Bacillus subtilis and competition assay with ATP were performed. The results showed that signermycin B binds to the dimerization domain but not the ATP-binding domain of WalK. In the presence of the cross-linker glutaraldehyde, signermycin B did not cause protein aggregation but interfered with the cross-linking of WalK dimers. These results suggest that signermycin B targets the conserved dimerization domain of WalK to inhibit autophosphorylation. In Bacillus subtilis and Staphylococcus aureus, signermycin B preferentially controlled the WalR regulon, thereby inhibiting cell division. These phenotypes are consistent with those of cells starved for the WalK/WalR system.
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Pancaldi V, Saraç ÖS, Rallis C, McLean JR, Převorovský M, Gould K, Beyer A, Bähler J. Predicting the fission yeast protein interaction network. G3 (BETHESDA, MD.) 2012; 2:453-67. [PMID: 22540037 PMCID: PMC3337474 DOI: 10.1534/g3.111.001560] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 01/31/2012] [Indexed: 12/03/2022]
Abstract
A systems-level understanding of biological processes and information flow requires the mapping of cellular component interactions, among which protein-protein interactions are particularly important. Fission yeast (Schizosaccharomyces pombe) is a valuable model organism for which no systematic protein-interaction data are available. We exploited gene and protein properties, global genome regulation datasets, and conservation of interactions between budding and fission yeast to predict fission yeast protein interactions in silico. We have extensively tested our method in three ways: first, by predicting with 70-80% accuracy a selected high-confidence test set; second, by recapitulating interactions between members of the well-characterized SAGA co-activator complex; and third, by verifying predicted interactions of the Cbf11 transcription factor using mass spectrometry of TAP-purified protein complexes. Given the importance of the pathway in cell physiology and human disease, we explore the predicted sub-networks centered on the Tor1/2 kinases. Moreover, we predict the histidine kinases Mak1/2/3 to be vital hubs in the fission yeast stress response network, and we suggest interactors of argonaute 1, the principal component of the siRNA-mediated gene silencing pathway, lost in budding yeast but preserved in S. pombe. Of the new high-quality interactions that were discovered after we started this work, 73% were found in our predictions. Even though any predicted interactome is imperfect, the protein network presented here can provide a valuable basis to explore biological processes and to guide wet-lab experiments in fission yeast and beyond. Our predicted protein interactions are freely available through PInt, an online resource on our website (www.bahlerlab.info/PInt).
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Affiliation(s)
- Vera Pancaldi
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Ömer S. Saraç
- Cellular Networks and Systems Biology, Biotechnology Center, Dresden University of Technology (TU Dresden), Dresden 01307, Germany, and
| | - Charalampos Rallis
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Janel R. McLean
- Howard Hughes Medical Institute
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Martin Převorovský
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Kathleen Gould
- Howard Hughes Medical Institute
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Andreas Beyer
- Cellular Networks and Systems Biology, Biotechnology Center, Dresden University of Technology (TU Dresden), Dresden 01307, Germany, and
| | - Jürg Bähler
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
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Thiazolidione derivatives targeting the histidine kinase YycG are effective against both planktonic and biofilm-associated Staphylococcus epidermidis. Acta Pharmacol Sin 2012; 33:418-25. [PMID: 22231397 DOI: 10.1038/aps.2011.166] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
AIM To evaluate the efficacies of six derivatives of Compound 2, a novel YycG histidine kinase inhibitor with the thiazolidione core structure in the treatment of medical device-related biofilm infections. METHODS The minimal inhibitory concentration (MIC) of the derivatives was determined using the macrodilution broth method, and the minimal bactericidal concentration (MBC) was obtained via sub-culturing 100 μL from each negative tube from the MIC assay onto drug-free Mueller-Hinton agar plates. Biofilm-killing effect for immature (6 h-old) biofilms was examined using a semiquantitative plate assay, and the effect on mature (24 h-old) biofilms was observed under a confocal laser scanning microscope (CLSM). RESULTS The derivatives potently suppressed the growth of Staphylococcus epidermidis. The MIC values of the derivatives H2-10, H2-12, H2-20, H2-29, H2-27, and H2-28 on S epidermidis ATCC 35984 were 24.3, 6.5, 6.2, 3.3, 3.1, and 1.5 μg/mL, respectively. The MBC values of these derivatives were 48.6, 52.2, 12.4, 52.6, 12.4, and 6.2 μg/mL, respectively. The derivatives killed all bacteria in immature (6 h-old) biofilms and eliminated the biofilm proliferation. The derivatives also displayed strong bactericidal activities toward cells in mature (24 h-old) biofilms, whereas they showed low cytotoxicity and hemolytic activity toward Vero cells and human erythrocytes. CONCLUSION The bactericidal and biofilm-killing activities of the new anti-YycG compounds were significantly better than the parent Compound 2.
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Ho YH, Sung TC, Chen CS. Lactoferricin B inhibits the phosphorylation of the two-component system response regulators BasR and CreB. Mol Cell Proteomics 2011; 11:M111.014720. [PMID: 22138548 DOI: 10.1074/mcp.m111.014720] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Natural antimicrobial peptides provide fundamental protection for multicellular organisms from microbes, such as Lactoferricin B (Lfcin B). Many studies have shown that Lfcin B penetrates the cell membrane and has intracellular activities. To elucidate the intracellular behavior of Lfcin B, we first used Escherichia coli K12 proteome chips to identify the intracellular targets of Lfcin B. The results showed that Lfcin B binds to two response regulators, BasR and CreB, of the two-component system. For further analysis, we conducted several in vitro and in vivo experiments and utilized bioinformatics methods. The electrophoretic mobility shift assays and kinase assays indicate that Lfcin B inhibits the phosphorylation of the response regulators (BasR and CreB) and their cognate sensor kinases (BasS and CreC). Antibacterial assays showed that Lfcin B reduced E. coli's tolerance to environmental stimuli, such as excessive ferric ions and minimal medium conditions. This is the first study to show that an antimicrobial peptide inhibits the growth of bacteria by influencing the phosphorylation of a two-component system directly.
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Affiliation(s)
- Yu-Hsuan Ho
- Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli 32001, Taiwan
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Shi T, Lu Y, Liu X, Chen Y, Jiang H, Zhang J. Mechanism for the autophosphorylation of CheA histidine kinase: QM/MM calculations. J Phys Chem B 2011; 115:11895-901. [PMID: 21910494 DOI: 10.1021/jp203968d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The CheA histidine kinase, a model of TCS (the two-component system), mediates the signal transduction pathway of bacterial chemotaxis via autophosphorylation. Since the TCSs are rarely found in mammalians, they have become attractive targets for the development of new antibiotics. To characterize the autophosphoryl-transfer mechanism of CheA histidine kinase, molecular dynamics simulations combined with quantum mechanics/molecular mechanics calculations were employed on the constructed 3D model of P1-P4-ATP complex. A two-step reaction mechanism was proposed and confirmed by our computations: the autophosphoryl-transfer reaction takes place followed by a rapid and reversible conformational change from ground state to prechemistry state. In addition, a two-dimensional potential energy surface was calculated for autophosphorylation, and the transition state displays an associative character. Moreover, we found Lys48 serves as the catalytic acid to stabilize transition state through a water-mediated proton-transfer pathway, and Glu67 acts as not only a hydrogen bond acceptor but also a structure anchor to modulate the imidazole ring of His45 in the active site. Our findings clearly provide a detailed autophosphoryl-transfer mechanism of CheA histidine kinase and thus are important for discovering new antibiotics.
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Affiliation(s)
- Ting Shi
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
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Abstract
Almost any process in life is accompanied by heat changes which can be monitored by isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Both techniques are now established tools in fundamental research but over the last decade a clear tendency towards more problem-driven applications is noted. This review aims at summarizing these problem-oriented applications of microcalorimetry and the solutions both techniques can provide to problems in biotechnology. The biotechnological issues to which microcalorimetry has been successfully applied are as diverse as rational drug design, overcoming drug resistance, optimization of long-term stability of proteins, estimation of the bioavailability of drugs, control of complex pharmaceutical products or the optimization of gene delivery efficiency. The main limitation of microcalorimetry, which is the relatively large amounts of sample necessary for analysis, is less important in the biotechnology sector which frequently uses large-scale produced bulk products for analysis. The recently developed high-throughput DSC and ITC microcalorimeters will additionally reduce the labour intensity of these techniques. Due to the precision of microcalorimetric analyses and the versatility of processes which can be studied, it is expected that ITC and DSC will soon be key technologies in biotechnological research.
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Affiliation(s)
- Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda 1, 18008 Granada, Spain.
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Guarnieri MT, Blagg BSJ, Zhao R. A high-throughput TNP-ATP displacement assay for screening inhibitors of ATP-binding in bacterial histidine kinases. Assay Drug Dev Technol 2010; 9:174-83. [PMID: 21050069 DOI: 10.1089/adt.2010.0289] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacterial histidine kinases (HK) are members of the GHKL superfamily, which share a unique adenosine triphosphate (ATP)-binding Bergerat fold. Our previous studies have shown that Gyrase, Hsp90, MutL (GHL) inhibitors bind to the ATP-binding pocket of HK and may provide lead compounds for the design of novel antibiotics targeting these kinases. In this article, we developed a competition assay using the fluorescent ATP analog, 2',3'-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate. The method can be used for high-throughput screening of compound libraries targeting HKs or other ATP-binding proteins. We utilized the assay to screen a library of GHL inhibitors targeting the bacterial HK PhoQ, and discuss the applications of the 2',3'-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate competition assay beyond GHKL inhibitor screening.
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Affiliation(s)
- Michael T Guarnieri
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, 80045, USA
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Carlin F, Brillard J, Broussolle V, Clavel T, Duport C, Jobin M, Guinebretière MH, Auger S, Sorokine A, Nguyen-Thé C. Adaptation of Bacillus cereus, an ubiquitous worldwide-distributed foodborne pathogen, to a changing environment. Food Res Int 2010. [DOI: 10.1016/j.foodres.2009.10.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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38
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Eaton AK, Stewart RC. Kinetics of ATP and TNP-ATP binding to the active site of CheA from Thermotoga maritima. Biochemistry 2010; 49:5799-809. [PMID: 20565117 DOI: 10.1021/bi100721b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanism of nucleotide binding to the active site of Thermotoga maritima CheA was investigated using stopped-flow fluorescence experiments that monitored binding of ATP and TNP-ATP to the catalytic domain (P4) of CheA that had been engineered to include a tryptophan residue as a fluorescent reporter group at the active site (P4(F487W)). Rapid decreases in protein intrinsic fluorescence and increases in TNP-ATP fluorescence were observed during binding reactions, and time courses were analyzed to define the kinetic mechanisms for ATP and TNP-ATP binding. This analysis indicated that binding of ATP(Mg(2+)) to P4(F487W) involves a single reversible step with a k(on) of 0.92 +/- 0.09 microM(-1) s(-1), a k(off) of 1.9 +/- 0.4 s(-1), and a K(d) of 1.5-2.1 microM (all values determined at 4 degrees C). Binding of TNP-ATP(Mg(2+)) to P4(F487W) involves a more complicated mechanism, requiring at least three sequential steps. Computer simulations and nonlinear regression analysis were used to estimate the rate constants of the forward and reverse reactions for each of the three steps in the reaction scheme [Formula: see text] Similar analysis indicated that an alternative reaction scheme, involving a rate-limiting conformational change in P4 prior to TNP-ATP binding, did an equally good job of accounting for all of the kinetics results:[Formula: see text] In both models, steps 2 and 3 have slow reversal rates that contribute to the high affinity of the active site for TNP-ATP (K(d) = 0.015 microM). These results highlight the dramatic effect of the TNP moieties on CheA-nucleotide interactions, and they provide the first detailed information about the kinetic mechanism underlying interaction of a protein histidine kinase with this tight-binding inhibitor.
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Affiliation(s)
- Anna K Eaton
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA
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White TA, Kell DB. Comparative genomic assessment of novel broad-spectrum targets for antibacterial drugs. Comp Funct Genomics 2010; 5:304-27. [PMID: 18629165 PMCID: PMC2447455 DOI: 10.1002/cfg.411] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Revised: 03/24/2004] [Accepted: 04/01/2004] [Indexed: 11/08/2022] Open
Abstract
Single and multiple resistance to antibacterial drugs currently in use is spreading, since they act against only a very small number of molecular targets; finding novel targets for anti-infectives is therefore of great importance. All protein sequences from three pathogens (Staphylococcus aureus, Mycobacterium tuberculosis and Escherichia coli O157:H7 EDL993) were assessed via comparative genomics methods for their suitability as antibacterial targets according to a number of criteria, including the essentiality of the protein, its level of sequence conservation, and its distribution in pathogens, bacteria and eukaryotes (especially humans). Each protein was scored and ranked based on weighted variants of these criteria in order to prioritize proteins as potential novel broad-spectrum targets for antibacterial drugs. A number of proteins proved to score highly in all three species and were robust to variations in the scoring system used. Sensitivity analysis indicated the quantitative contribution of each metric to the overall score. After further analysis of these targets, tRNA methyltransferase (trmD) and translation initiation factor IF-1 (infA) emerged as potential and novel antimicrobial targets very worthy of further investigation. The scoring strategy used might be of value in other areas of post-genomic drug discovery.
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Affiliation(s)
- Thomas A White
- Department of Biology, University of York, Heslington, York YO10 5YW, UK
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40
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Gotoh Y, Eguchi Y, Watanabe T, Okamoto S, Doi A, Utsumi R. Two-component signal transduction as potential drug targets in pathogenic bacteria. Curr Opin Microbiol 2010; 13:232-9. [PMID: 20138000 DOI: 10.1016/j.mib.2010.01.008] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 01/12/2010] [Accepted: 01/12/2010] [Indexed: 11/16/2022]
Abstract
Gene clusters contributing to processes such as cell growth and pathogenicity are often controlled by two-component signal transduction systems (TCSs). Specific inhibitors against TCS systems work differently from conventional antibiotics, and developing them into new drugs that are effective against various drug-resistant bacteria may be possible. Furthermore, inhibitors of TCSs that control virulence factors may reduce virulence without killing the pathogenic bacteria. Previous TCS inhibitors targeting the kinase domain of the histidine kinase sensor suffered from poor selectivity. Recent TCS inhibitors, however, target the sensory domains of the sensors blocking the quorum sensing system, or target the essential response regulator. These new targets are introduced, together with several specific TCSs that have the potential to serve as effective drug targets.
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Affiliation(s)
- Yasuhiro Gotoh
- Department of Bioscience, Graduate School of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan
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41
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Novel antibacterial compounds specifically targeting the essential WalR response regulator. J Antibiot (Tokyo) 2010; 63:127-34. [PMID: 20111065 DOI: 10.1038/ja.2010.4] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The WalK/WalR (YycG/YycF) two-component system, which is essential for cell viability, is highly conserved and specific to low-GC percentage of Gram-positive bacteria, making it an attractive target for novel antimicrobial compounds. Recent work has shown that WalK/WalR exerts an effect as a master regulatory system in controlling and coordinating cell wall metabolism with cell division in Bacillus subtilis and Staphylococcus aureus. In this paper, we develop a high-throughput screening system for WalR inhibitors and identify two novel inhibitors targeting the WalR response regulator (RR): walrycin A (4-methoxy-1-naphthol) and walrycin B (1,6-dimethyl-3-[4-(trifluoromethyl)phenyl]pyrimido[5,4-e][1,2,4]triazine-5,7-dione). Addition of these compounds simultaneously affects the expression of WalR regulon genes, leading to phenotypes consistent with those of cells starved for the WalK/WalR system and having a bactericidal effect. B. subtilis cells form extremely long aseptate filaments and S. aureus cells form large aggregates under these conditions. These results show that walrycins A and B are the first antibacterial agents targeting WalR in B. subtilis and S. aureus.
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Characterization of the sporulation initiation pathway of Clostridium difficile and its role in toxin production. J Bacteriol 2009; 191:7296-305. [PMID: 19783633 DOI: 10.1128/jb.00882-09] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Clostridium difficile is responsible for significant mortality and morbidity in the hospitalized elderly. C. difficile spores are infectious and are a major factor contributing to nosocomial transmission. The Spo0A response regulator is the master regulator for sporulation initiation and can influence many other cellular processes. Using the ClosTron gene knockout system, we inactivated genes encoding Spo0A and a putative sporulation-associated sensor histidine kinase in C. difficile. Inactivation of spo0A resulted in an asporogeneous phenotype, whereas inactivation of the kinase reduced C. difficile sporulation capacity by 3.5-fold, suggesting that this kinase also has a role in sporulation initiation. Furthermore, inactivation of either spo0A or the kinase resulted in a marked defect in C. difficile toxin production. Therefore, Spo0A and the signaling pathway that modulates its activity appear to be involved in regulation of toxin synthesis in C. difficile. In addition, Spo0A was directly phosphorylated by a putative sporulation-associated kinase, supporting the hypothesis that sporulation initiation in C. difficile is controlled by a two-component signal transduction system rather than a multicomponent phosphorelay. The implications of these findings for C. difficile sporulation, virulence, and transmission are discussed.
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Mack TR, Gao R, Stock AM. Probing the roles of the two different dimers mediated by the receiver domain of the response regulator PhoB. J Mol Biol 2009; 389:349-64. [PMID: 19371748 DOI: 10.1016/j.jmb.2009.04.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2009] [Revised: 04/08/2009] [Accepted: 04/08/2009] [Indexed: 12/28/2022]
Abstract
Structural analysis of the Escherichia coli response regulator transcription factor PhoB indicates that the protein dimerizes in two different orientations that are both mediated by the receiver domain. The two dimers exhibit 2-fold rotational symmetry: one involves the alpha 4-beta 5-alpha 5 surface and the other involves the alpha1/alpha 5 surface. The alpha 4-beta 5-alpha 5 dimer is observed when the protein is crystallized in the presence of the phosphoryl analog BeF(3)(-), while the alpha1/alpha 5 dimer is observed in its absence. From these studies, a model of the inactive and active states of PhoB has been proposed that involves the formation of two distinct dimers. In order to gain further insight into the roles of these dimers, we have engineered a series of mutations in PhoB intended to perturb each of them selectively. Our results indicate that perturbation of the alpha 4-beta 5-alpha 5 surface disrupts phosphorylation-dependent dimerization and DNA binding as well as PhoB-mediated transcriptional activation of phoA, while perturbations to the alpha1/alpha 5 surface do not. Furthermore, experiments with a GCN4 leucine zipper/PhoB chimera protein indicate that PhoB is activated through an intermolecular mechanism. Together, these results support a model of activation of PhoB in which phosphorylation promotes dimerization via the alpha 4-beta 5-alpha 5 face, which enhances DNA binding and thus the ability of PhoB to regulate transcription.
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Affiliation(s)
- Timothy R Mack
- Center for Advanced Biotechnology and Medicine, 679 Hoes Lane, Piscataway, NJ 08854, USA
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44
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Whitworth DE, Cock PJA. Evolution of prokaryotic two-component systems: insights from comparative genomics. Amino Acids 2009; 37:459-66. [DOI: 10.1007/s00726-009-0259-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 02/02/2009] [Indexed: 01/22/2023]
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45
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Lin YH, Gao R, Binns AN, Lynn DG. Capturing the VirA/VirG TCS of Agrobacterium tumefaciens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 631:161-77. [PMID: 18792688 DOI: 10.1007/978-0-387-78885-2_11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Two-component systems (TCS) regulate pathogenic commitment in many interactions and provide an opportunity for unique therapeutic intervention. The VirA/VirG TCS of Agrobacterium tumefaciens mediates inter-kingdom gene transfer in the development of host tumors and sets in motion the events that underlie the great success of this multi-host plant pathogen. Significant proof for the feasibility of interventions has now emerged with the discovery of a natural product that effectively "blinds" the pathogen to the host via inhibition of VirA/VirG signal transduction. Moreover, the emerging studies on the mechanism of signal perception have revealed general sites suitable for intervention of TCS signaling. Given the extensive functional homology, it should now be possible to transfer the models discovered for VirA/VirG broadly to other pathogenic interactions.
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Affiliation(s)
- Yi-Han Lin
- Center for Fundamental and Applied Molecular Evolution, Department of Chemistry, Emory University, Atlanta, GA 30322, USA
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46
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Cunningham KA, Burkholder WF. The histidine kinase inhibitor Sda binds near the site of autophosphorylation and may sterically hinder autophosphorylation and phosphotransfer to Spo0F. Mol Microbiol 2008; 71:659-77. [PMID: 19040634 DOI: 10.1111/j.1365-2958.2008.06554.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Histidine kinases are widely used by bacteria, fungi and plants to sense and respond to changing environmental conditions. Signals in addition to those directly sensed by the kinase are often integrated by proteins that fine-tune the biological response by modulating the activity of the kinase or its targets. The Bacillus subtilis histidine kinase KinA promotes the initiation of sporulation when nutrients are limiting, but sporulation can be delayed by two inhibitors of KinA, Sda (when DNA replication is perturbed) or KipI (under unknown conditions). We have identified residues in the dimerization/histidine-phosphotransfer (DHp) domain of KinA that are functionally important for inhibition by Sda and KipI and overlapping surface-exposed residues that lie close to or comprise the Sda binding site. Sda inhibits the intermolecular transfer of phosphate from the catalytic ATP-binding (CA) domain of KinA to the autophosphorylation site in the DHp domain when the domains are split into separate polypeptides, either by steric hindrance or by altering the conformation of the DHp domain. Sda also slows the rate of phosphotransfer from KinA approximately P to its target, Spo0F, consistent with our finding that a KinA residue important for Sda function overlaps with the predicted Spo0F binding site on KinA.
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47
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Yeo KJ, Kwak SN, Kim HJ, Cheong C, Kim MH, Jeon YH. Expression and characterization of the integral membrane domain of bacterial histidine kinase SCO3062 for structural studies. Biochem Biophys Res Commun 2008; 376:409-13. [DOI: 10.1016/j.bbrc.2008.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 09/03/2008] [Indexed: 10/21/2022]
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Kowluru A. Emerging roles for protein histidine phosphorylation in cellular signal transduction: lessons from the islet beta-cell. J Cell Mol Med 2008; 12:1885-908. [PMID: 18400053 PMCID: PMC4506158 DOI: 10.1111/j.1582-4934.2008.00330.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein phosphorylation represents one of the key regulatory events in physiological insulin secretion from the islet β-cell. In this context, several classes of protein kinases (e.g. calcium-, cyclic nucleotide- and phospholipid-dependent protein kinases and tyrosine kinases) have been characterized in the β-cell. The majority of phosphorylated amino acids identified include phosphoserine, phosphothreonine and phosphotyrosine. Protein histidine phosphorylation has been implicated in the prokaryotic and eukaryotic cellular signal transduction. Most notably, phoshohistidine accounts for 6% of total protein phosphorylation in eukaryotes, which makes it nearly 100-fold more abundant than phosphotyrosine, but less abundant than phosphoserine and phosphothreonine. However, very little is known about the number of proteins with phosphohistidines, since they are highly labile and are rapidly lost during phosphoamino acid identification under standard experimental conditions. The overall objectives of this review are to: (i) summarize the existing evidence indicating the subcellular distribution and characterization of various histidine kinases in the islet β-cell, (ii) describe evidence for functional regulation of these kinases by agonists of insulin secretion, (iii) present a working model to implicate novel regulatory roles for histidine kinases in the receptor-independent activation, by glucose, of G-proteins endogenous to the β-cell, (iv) summarize evidence supporting the localization of protein histidine phosphatases in the islet β-cell and (v) highlight experimental evidence suggesting potential defects in the histidine kinase signalling cascade in islets derived from the Goto-Kakizaki (GK) rat, a model for type 2 diabetes. Potential avenues for future research to further decipher regulatory roles for protein histidine phosphorylation in physiological insulin secretion are also discussed.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.
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Essentiality, bypass, and targeting of the YycFG (VicRK) two-component regulatory system in gram-positive bacteria. J Bacteriol 2008; 190:2645-8. [PMID: 18245295 DOI: 10.1128/jb.01682-07] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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Lamarche MG, Wanner BL, Crépin S, Harel J. The phosphate regulon and bacterial virulence: a regulatory network connecting phosphate homeostasis and pathogenesis. FEMS Microbiol Rev 2008; 32:461-73. [PMID: 18248418 DOI: 10.1111/j.1574-6976.2008.00101.x] [Citation(s) in RCA: 315] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Bacterial pathogens regulate virulence factor gene expression coordinately in response to environmental stimuli, including nutrient starvation. The phosphate (Pho) regulon plays a key role in phosphate homeostasis. It is controlled by the PhoR/PhoB two-component regulatory system. PhoR is an integral membrane signaling histidine kinase that, through an interaction with the ABC-type phosphate-specific transport (Pst) system and a protein called PhoU, somehow senses environmental inorganic phosphate (P(i)) levels. Under conditions of P(i) limitation (or in the absence of a Pst component or PhoU), PhoR activates its partner response regulator PhoB by phosphorylation, which, in turn, up- or down-regulates target genes. Single-cell profiling of PhoB activation has shown recently that Pho regulon gene expression exhibits a stochastic, "all-or-none" behavior. Recent studies have also shown that the Pho regulon plays a role in the virulence of several bacteria. Here, we present a comprehensive overview of the role of the Pho regulon in bacterial virulence. The Pho regulon is clearly not a simple regulatory circuit for controlling phosphate homeostasis; it is part of a complex network important for both bacterial virulence and stress response.
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Affiliation(s)
- Martin G Lamarche
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
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