1
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Zhang Q, Wei Z, Jia X. Controllable detection threshold achieved through the toehold switch system in a mercury ion whole-cell biosensor. Biosens Bioelectron 2024; 256:116283. [PMID: 38608495 DOI: 10.1016/j.bios.2024.116283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 04/02/2024] [Accepted: 04/08/2024] [Indexed: 04/14/2024]
Abstract
Due to the toxicity of mercury and its harmful effects on human health, it is essential to establish a low-cost, highly sensitive and highly specific monitoring method with a wide detection range, ideally with a simple visual readout. In this study, a whole-cell biosensor with adjustable detection limits was developed for the detection of mercury ions in water samples, allowing controllable threshold detection with an expanded detection range. Gene circuits were constructed by combining the toehold switch system with lactose operon, mercury-ion-specific operon, and inducible red fluorescent protein gene. Using MATLAB for design and selection, a total of eleven dual-input single-output sensing logic circuits were obtained based on the basic logic of gene circuit construction. Then, biosensor DTS-3 was selected based on its fluorescence response at different isopropyl β-D-Thiogalactoside (IPTG) concentrations, exhibiting the controllable detection threshold. At 5-20 μM IPTG, DTS-3 can achieve variable threshold detection in the range of 0.005-0.0075, 0.06-0.08, 1-2, and 4-6 μM mercury ion concentrations, respectively. Specificity experiments demonstrated that DTS-3 exhibits good specificity, not showing fluorescence response changes compared with other metal ions. Furthermore spiked sample experiments demonstrated its good resistance to interference, allowing it to distinguish mercury ion concentrations as low as 7.5 nM by the naked eye and 5 nM using a microplate reader. This study confirms the feasibility and performance of biosensor with controllable detection threshold, providing a new detection method and new ideas for expanding the detection range of biosensors while ensuring rapid and convenient measurements without compromising sensitivity.
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Affiliation(s)
- Qinglong Zhang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China.
| | - Zixiang Wei
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China.
| | - Xiaoqiang Jia
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, PR China; Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, PR China.
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2
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Liu T, Li C, Quan X. Toxic effect of copper ions on anammox in IFFAS process filled with ZVI-10 modified carriers. ENVIRONMENTAL RESEARCH 2024; 243:117893. [PMID: 38081347 DOI: 10.1016/j.envres.2023.117893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/06/2023] [Accepted: 12/06/2023] [Indexed: 02/06/2024]
Abstract
The inhibitory effects of heavy metals on anammox bacteria (AnAOB) have attracted attention worldwide. However, most are conducted in activated sludge rather than biofilm systems. The toxic effect and resistance response of anammox biofilm are not predictable from those of free-living AnAOB. Zero valent iron (ZVI) has been demonstrated to enhance anammox performance, but whether ZVI can promote AnAOB resistance to heavy metal stress remains unclear. Herein, the toxic effect of copper ions (Cu(II)) on anammox in integrated floating-film activated sludge (IFFAS) process filled with 10 wt% ZVI modified carriers (R1) was investigated. Results indicated half inhibiting concentration (IC50) of Cu(II) in R1 was 9.13 mg/L, which was much higher than that in R0 filled with conventional carriers made of high density polyethylene (HDPE) (3.94 mg/L). Long-term effect of Cu(II) demonstrated that Cu(II) concentrations less than 1.0 mg/L could not inhibit anammox biofilm significantly, whereas R1 performed better anammox process than R0 under the stress of 0.1-1.0 mg/L Cu(II). The ZVI modified carriers induced more extracellular polymeric substances (EPS) to trap Cu(II) to attenuate the toxicity to AnAOB. Besides, the activities of functional enzymes related to anammox (NIR and HDH), as well as heme-c contents, were always higher in R1 than R0 regardless of the Cu(II) dosage. Candidatus Kuenenia was identified as the predominant AnAOB, which had stronger resistance to Cu(II) stress compared to other genera in the IFFAS process. Metal resistance genes (MRGs) analysis identified AnAOB induced multi-responses to resist Cu(II) stress, such as the up-regulation of copC, cutA, cutC, cutF, cueR and cueO, to synthesize more proteins with functions of copper exocytosis, conjugation and oxidation.
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Affiliation(s)
- Tao Liu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
| | - Chaohui Li
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Xie Quan
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
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3
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Hu Y, Liu B. The Copper Efflux Regulator (CueR). Subcell Biochem 2024; 104:17-31. [PMID: 38963481 DOI: 10.1007/978-3-031-58843-3_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The copper efflux regulator (CueR) is a classical member of the MerR family of metalloregulators and is common in gram-negative bacteria. Through its C-terminal effector-binding domain, CueR senses cytoplasmic copper ions to regulate the transcription of genes contributing to copper homeostasis, an essential process for survival of all cells. In this chapter, we review the regulatory roles of CueR in the model organism Escherichia coli and the mechanisms for CueR in copper binding, DNA recognition, and interplay with RNA polymerase in regulating transcription. In light of biochemical and structural analyses, we provide molecular details for how CueR represses transcription in the absence of copper ions, how copper ions mediate CueR conformational change to form holo CueR, and how CueR bends and twists promoter DNA to activate transcription. We also characterize the functional domains and key residues involved in these processes. Since CueR is a representative member of the MerR family, elucidating its regulatory mechanisms could help to understand the CueR-like regulators in other organisms and facilitate the understanding of other metalloregulators in the same family.
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Affiliation(s)
- Yangbo Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.
| | - Bin Liu
- Section of Transcription & Gene Regulation, The Hormel Institute, University of Minnesota, Austin, MN, USA.
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4
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Patil RS, Sharma S, Bhaskarwar AV, Nambiar S, Bhat NA, Koppolu MK, Bhukya H. TetR and OmpR family regulators in natural product biosynthesis and resistance. Proteins 2023. [PMID: 37874037 DOI: 10.1002/prot.26621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 08/30/2023] [Accepted: 10/06/2023] [Indexed: 10/25/2023]
Abstract
This article provides a comprehensive review and sequence-structure analysis of transcription regulator (TR) families, TetR and OmpR/PhoB, involved in specialized secondary metabolite (SSM) biosynthesis and resistance. Transcription regulation is a fundamental process, playing a crucial role in orchestrating gene expression to confer a survival advantage in response to frequent environmental stress conditions. This process, coupled with signal sensing, enables bacteria to respond to a diverse range of intra and extracellular signals. Thus, major bacterial signaling systems use a receptor domain to sense chemical stimuli along with an output domain responsible for transcription regulation through DNA-binding. Sensory and output domains on a single polypeptide chain (one component system, OCS) allow response to stimuli by allostery, that is, DNA-binding affinity modulation upon signal presence/absence. On the other hand, two component systems (TCSs) allow cross-talk between the sensory and output domains as they are disjoint and transmit information by phosphorelay to mount a response. In both cases, however, TRs play a central role. Biosynthesis of SSMs, which includes antibiotics, is heavily regulated by TRs as it diverts the cell's resources towards the production of these expendable compounds, which also have clinical applications. These TRs have evolved to relay information across specific signals and target genes, thus providing a rich source of unique mechanisms to explore towards addressing the rapid escalation in antimicrobial resistance (AMR). Here, we focus on the TetR and OmpR family TRs, which belong to OCS and TCS, respectively. These TR families are well-known examples of regulators in secondary metabolism and are ubiquitous across different bacteria, as they also participate in a myriad of cellular processes apart from SSM biosynthesis and resistance. As a result, these families exhibit higher sequence divergence, which is also evident from our bioinformatic analysis of 158 389 and 77 437 sequences from TetR and OmpR family TRs, respectively. The analysis of both sequence and structure allowed us to identify novel motifs in addition to the known motifs responsible for TR function and its structural integrity. Understanding the diverse mechanisms employed by these TRs is essential for unraveling the biosynthesis of SSMs. This can also help exploit their regulatory role in biosynthesis for significant pharmaceutical, agricultural, and industrial applications.
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Affiliation(s)
- Rachit S Patil
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Siddhant Sharma
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Aditya V Bhaskarwar
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Souparnika Nambiar
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Niharika A Bhat
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Mani Kanta Koppolu
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Hussain Bhukya
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
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5
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Ghataora JS, Gebhard S, Reeksting BJ. Chimeric MerR-Family Regulators and Logic Elements for the Design of Metal Sensitive Genetic Circuits in Bacillus subtilis. ACS Synth Biol 2023; 12:735-749. [PMID: 36629785 PMCID: PMC10028694 DOI: 10.1021/acssynbio.2c00545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Whole-cell biosensors are emerging as promising tools for monitoring environmental pollutants such as heavy metals. These sensors constitute a genetic circuit comprising a sensing module and an output module, such that a detectable signal is produced in the presence of the desired analyte. The MerR family of metal-responsive regulators offers great potential for the construction of metal sensing circuits, due to their high sensitivity, tight transcription control, and large diversity in metal-specificity. However, the sensing diversity is broadest in Gram-negative systems, while chassis organisms are often selected from Gram-positive species, particularly sporulating bacilli. This can be problematic, because Gram-negative biological parts, such as promoters, are frequently observed to be nonfunctional in Gram-positive hosts. Herein, we combined construction of synthetic genetic circuits and chimeric MerR regulators, supported by structure-guided design, to generate metal-sensitive biosensor modules that are functional in the biotechnological work-horse species Bacillus subtilis. These chimeras consist of a constant Gram-positive derived DNA-binding domain fused to variable metal binding domains of Gram-negative origins. To improve the specificity of the whole-cell biosensor, we developed a modular "AND gate" logic system based on the B. subtilis two-subunit σ-factor, SigO-RsoA, designed to maximize future use for synthetic biology applications in B. subtilis. This work provides insights into the use of modular regulators, such as the MerR family, in the design of synthetic circuits for the detection of heavy metals, with potentially wider applicability of the approach to other systems and genetic backgrounds.
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Affiliation(s)
- Jasdeep S Ghataora
- Life Sciences Department, Milner Centre for Evolution, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Susanne Gebhard
- Life Sciences Department, Milner Centre for Evolution, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Bianca J Reeksting
- Life Sciences Department, Milner Centre for Evolution, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
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6
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Fritsch VN, Linzner N, Busche T, Said N, Weise C, Kalinowski J, Wahl MC, Antelmann H. The MerR-family regulator NmlR is involved in the defense against oxidative stress in Streptococcus pneumoniae. Mol Microbiol 2023; 119:191-207. [PMID: 36349475 DOI: 10.1111/mmi.14999] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/25/2022] [Accepted: 10/30/2022] [Indexed: 11/11/2022]
Abstract
Streptococcus pneumoniae has to cope with the strong oxidant hypochlorous acid (HOCl), during host-pathogen interactions. Thus, we analyzed the global gene expression profile of S. pneumoniae D39 towards HOCl stress. In the RNA-seq transcriptome, the NmlR, SifR, CtsR, HrcA, SczA and CopY regulons and the etrx1-ccdA1-msrAB2 operon were most strongly induced under HOCl stress, which participate in the oxidative, electrophile and metal stress response in S. pneumoniae. The MerR-family regulator NmlR harbors a conserved Cys52 and controls the alcohol dehydrogenase-encoding adhC gene under carbonyl and NO stress. We demonstrated that NmlR senses also HOCl stress to activate transcription of the nmlR-adhC operon. HOCl-induced transcription of adhC required Cys52 of NmlR in vivo. Using mass spectrometry, NmlR was shown to be oxidized to intersubunit disulfides or S-glutathionylated under oxidative stress in vitro. A broccoli-FLAP-based assay further showed that both NmlR disulfides significantly increased transcription initiation at the nmlR promoter by RNAP in vitro, which depends on Cys52. Phenotype analyses revealed that NmlR functions in the defense against oxidative stress and promotes survival of S. pneumoniae during macrophage infections. In conclusion, NmlR was characterized as HOCl-sensing transcriptional regulator, which activates transcription of adhC under oxidative stress by thiol switches in S. pneumoniae.
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Affiliation(s)
| | - Nico Linzner
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
| | - Tobias Busche
- Center for Biotechnology, University Bielefeld, Bielefeld, Germany.,NGS Core Facility, Medical School OWL, Bielefeld University, Bielefeld, Germany
| | - Nelly Said
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Christoph Weise
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Jörn Kalinowski
- Center for Biotechnology, University Bielefeld, Bielefeld, Germany
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany.,Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| | - Haike Antelmann
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
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7
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Wu J, Liu Y, Li W, Li F, Liu R, Sun H, Qin J, Feng X, Huang D, Liu B. MlrA, a MerR family regulator in Vibrio cholerae, senses the anaerobic signal in the small intestine of the host to promote bacterial intestinal colonization. Gut Microbes 2022; 14:2143216. [PMID: 36369865 PMCID: PMC9662190 DOI: 10.1080/19490976.2022.2143216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vibrio cholerae (V. cholerae), one of the most important bacterial pathogens in history, is a gram-negative motile bacterium that causes fatal pandemic disease in humans via oral ingestion of contaminated water or food. This process involves the coordinated actions of numerous regulatory factors. The MerR family regulators, which are widespread in prokaryotes, have been reported to be associated with pathogenicity. However, the role of the MerR family regulators in V. cholerae virulence remains unknown. Our study systematically investigated the influence of MerR family regulators on intestinal colonization of V. cholerae within the host. Among the five MerR family regulators, MlrA was found to significantly promote the colonization capacity of V. cholerae in infant mice. Furthermore, we revealed that MlrA increases bacterial intestinal colonization by directly enhancing the expression of tcpA, which encodes one of the most important virulence factors in V. cholerae, by binding to its promoter region. In addition, we revealed that during infection, mlrA is activated by anaerobic signals in the small intestine of the host through Fnr. In summary, our findings reveal a MlrA-mediated virulence regulation pathway that enables V. cholerae to sense environmental signals at the infection site to precisely activate virulence gene expression, thus providing useful insights into the pathogenic mechanisms of V. cholerae.
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Affiliation(s)
- Jialin Wu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Yutao Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China,Nankai International Advanced Research Institute, Nankai University Shenzhen, China
| | - Wendi Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Fan Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Ruiying Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Hao Sun
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Jingliang Qin
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Xiaohui Feng
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Di Huang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China,Nankai International Advanced Research Institute, Nankai University Shenzhen, China,Di Huang TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China,Nankai International Advanced Research Institute, Nankai University Shenzhen, China,CONTACT Bin Liu TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
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8
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Abril AG, Quintela-Baluja M, Villa TG, Calo-Mata P, Barros-Velázquez J, Carrera M. Proteomic Characterization of Virulence Factors and Related Proteins in Enterococcus Strains from Dairy and Fermented Food Products. Int J Mol Sci 2022; 23:ijms231810971. [PMID: 36142880 PMCID: PMC9503237 DOI: 10.3390/ijms231810971] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/08/2022] [Accepted: 09/16/2022] [Indexed: 01/23/2023] Open
Abstract
Enterococcus species are Gram-positive bacteria that are normal gastrointestinal tract inhabitants that play a beneficial role in the dairy and meat industry. However, Enterococcus species are also the causative agents of health care-associated infections that can be found in dairy and fermented food products. Enterococcal infections are led by strains of Enterococcus faecalis and Enterococcus faecium, which are often resistant to antibiotics and biofilm formation. Enterococci virulence factors attach to host cells and are also involved in immune evasion. LC-MS/MS-based methods offer several advantages compared with other approaches because one can directly identify microbial peptides without the necessity of inferring conclusions based on other approaches such as genomics tools. The present study describes the use of liquid chromatography−electrospray ionization tandem mass spectrometry (LC−ESI−MS/MS) to perform a global shotgun proteomics characterization for opportunistic pathogenic Enterococcus from different dairy and fermented food products. This method allowed the identification of a total of 1403 nonredundant peptides, representing 1327 proteins. Furthermore, 310 of those peptides corresponded to proteins playing a direct role as virulence factors for Enterococcus pathogenicity. Virulence factors, antibiotic sensitivity, and proper identification of the enterococcal strain are required to propose an effective therapy. Data are available via ProteomeXchange with identifier PXD036435. Label-free quantification (LFQ) demonstrated that the majority of the high-abundance proteins corresponded to E. faecalis species. Therefore, the global proteomic repository obtained here can be the basis for further research into pathogenic Enterococcus species, thus facilitating the development of novel therapeutics.
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Affiliation(s)
- Ana G. Abril
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, 15898 Santiago de Compostela, Spain
- Department of Food Technology, Spanish National Research Council (CSIC), Marine Research Institute (IIM), 36208 Vigo, Spain
| | - Marcos Quintela-Baluja
- Department of Analytical Chemistry, Nutrition and Food Science, Food Technology Division, School of Veterinary Sciences, University of Santiago de Compostela, Campus Lugo, 27002 Lugo, Spain
| | - Tomás G. Villa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, 15898 Santiago de Compostela, Spain
| | - Pilar Calo-Mata
- Department of Analytical Chemistry, Nutrition and Food Science, Food Technology Division, School of Veterinary Sciences, University of Santiago de Compostela, Campus Lugo, 27002 Lugo, Spain
| | - Jorge Barros-Velázquez
- Department of Analytical Chemistry, Nutrition and Food Science, Food Technology Division, School of Veterinary Sciences, University of Santiago de Compostela, Campus Lugo, 27002 Lugo, Spain
| | - Mónica Carrera
- Department of Food Technology, Spanish National Research Council (CSIC), Marine Research Institute (IIM), 36208 Vigo, Spain
- Correspondence:
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9
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Balogh RK, Gyurcsik B, Jensen M, Thulstrup PW, Köster U, Christensen NJ, Jensen ML, Hunyadi-Gulyás É, Hemmingsen L, Jancso A. Tying up a loose end: On the role of the C-terminal CCHHRAG fragment of the metalloregulator CueR. Chembiochem 2022; 23:e202200290. [PMID: 35714117 PMCID: PMC9542689 DOI: 10.1002/cbic.202200290] [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: 05/20/2022] [Indexed: 11/07/2022]
Abstract
The transcriptional regulator CueR is activated by the binding of CuI, AgI, or AuI to two cysteinates in a near‐linear fashion. The C‐terminal CCHHRAG sequence in Escherichia coli CueR present potential additional metal binding ligands and here we explore the effect of deleting this fragment on the binding of AgI to CueR. CD spectroscopic and ESI‐MS data indicate that the high AgI‐binding affinity of WT‐CueR is significantly reduced in Δ7C‐CueR.[111 Ag PAC spectroscopy demonstrates that the WT‐CueR metal site structure (AgS2) is conserved, but less populated in the truncated variant. Thus, the function of the C‐terminal fragment may be to stabilize the two‐coordinate metal site for cognate monovalent metal ions. In a broader perspective this is an example of residues beyond the second coordination sphere affecting metal site physicochemical properties while leaving the structure unperturbed.
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Affiliation(s)
- Ria K Balogh
- University of Szeged: Szegedi Tudomanyegyetem, Department of Inorganic and Analytical Chemistry, HUNGARY
| | - Béla Gyurcsik
- University of Szeged: Szegedi Tudomanyegyetem, Department of Inorganic and Analytical Chemistry, HUNGARY
| | - Mikael Jensen
- Technical University of Denmark: Danmarks Tekniske Universitet, Hevesy Laboratory, Center for Nuclear Technologies, DENMARK
| | - Peter W Thulstrup
- University of Copenhagen: Kobenhavns Universitet, Department of Chemistry, DENMARK
| | - Ulli Köster
- Institut Laue-Langevin, Institut Laue-Langevin, FRANCE
| | - Niels Johan Christensen
- University of Copenhagen: Kobenhavns Universitet, Department of Chemistry, Faculty of Science, DENMARK
| | - Marianne L Jensen
- Niels Bohr Instituttet: Kobenhavns Universitet Niels Bohr Instituttet, Niels Bohr Institute, DENMARK
| | - Éva Hunyadi-Gulyás
- Biological Research Centre, Szeged, Laboratory of Proteomics Research, HUNGARY
| | - Lars Hemmingsen
- University of Copenhagen: Kobenhavns Universitet, Department of Chemistry, DENMARK
| | - Attila Jancso
- University of Szeged, Department of Inorganic and Analytical Chemistry, Dóm tér 7., 6720, Szeged, HUNGARY
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10
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Elsayed A, Moussa Z, Alrdahe SS, Alharbi MM, Ghoniem AA, El-khateeb AY, Saber WIA. Optimization of Heavy Metals Biosorption via Artificial Neural Network: A Case Study of Cobalt (II) Sorption by Pseudomonas alcaliphila NEWG-2. Front Microbiol 2022; 13:893603. [PMID: 35711743 PMCID: PMC9194897 DOI: 10.3389/fmicb.2022.893603] [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: 03/10/2022] [Accepted: 05/02/2022] [Indexed: 02/03/2023] Open
Abstract
The definitive screening design (DSD) and artificial neural network (ANN) were conducted for modeling the biosorption of Co(II) by Pseudomonas alcaliphila NEWG-2. Factors such as peptone, incubation time, pH, glycerol, glucose, K2HPO4, and initial cobalt had a significant effect on the biosorption process. MgSO4 was the only insignificant factor. The DSD model was invalid and could not forecast the prediction of Co(II) removal, owing to the significant lack-of-fit (P < 0.0001). Decisively, the prediction ability of ANN was accurate with a prominent response for training (R2 = 0.9779) and validation (R2 = 0.9773) and lower errors. Applying the optimal levels of the tested variables obtained by the ANN model led to 96.32 ± 2.1% of cobalt bioremoval. During the biosorption process, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy, and scanning electron microscopy confirmed the sorption of Co(II) ions by P. alcaliphila. FTIR indicated the appearance of a new stretching vibration band formed with Co(II) ions at wavenumbers of 562, 530, and 531 cm-1. The symmetric amino (NH2) binding was also formed due to Co(II) sorption. Interestingly, throughout the revision of publications so far, no attempt has been conducted to optimize the biosorption of Co(II) by P. alcaliphila via DSD or ANN paradigm.
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Affiliation(s)
- Ashraf Elsayed
- Botany Department, Faculty of Science, Mansoura University, Mansoura, Egypt
| | - Zeiad Moussa
- Department of Microbiology, Soils, Water and Environment Research Institute, Agricultural Research Center, Giza, Egypt
| | - Salma Saleh Alrdahe
- Department of Biology, Faculty of Science, University of Tabuk, Tabuk, Saudi Arabia
| | | | - Abeer A. Ghoniem
- Department of Microbiology, Soils, Water and Environment Research Institute, Agricultural Research Center, Giza, Egypt
| | - Ayman Y. El-khateeb
- Department of Agricultural Chemistry, Faculty of Agriculture, Mansoura University, Mansoura, Egypt
| | - WesamEldin I. A. Saber
- Department of Microbiology, Soils, Water and Environment Research Institute, Agricultural Research Center, Giza, Egypt
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11
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Mahas A, Wang Q, Marsic T, Mahfouz MM. Development of Cas12a-Based Cell-Free Small-Molecule Biosensors via Allosteric Regulation of CRISPR Array Expression. Anal Chem 2022; 94:4617-4626. [PMID: 35266687 PMCID: PMC8943526 DOI: 10.1021/acs.analchem.1c04332] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
Cell-free biosensors
can detect various molecules, thus promising
to transform the landscape of diagnostics. Here, we developed a simple,
rapid, sensitive, and field-deployable small-molecule detection platform
based on allosteric transcription factor (aTF)-regulated expression
of a clustered regularly interspaced short palindromic repeats (CRISPR)
array coupled to Cas12a activity. To this end, we engineered an expression
cassette harboring a T7 promoter, an aTF binding sequence, a Cas12a
CRISPR array, and protospacer adjacent motif-flanked Cas12a target
sequences. In the presence of the ligand, dissociation of the aTF
allows transcription of the CRISPR array; this leads to activation
of Cas12a collateral activity, which cleaves a single-stranded DNA
linker to free a quenched fluorophore, resulting in a rapid, significant
increase of fluorescence. As a proof of concept, we used TetR as the
aTF to detect different tetracycline antibiotics with high sensitivity
and specificity and a simple, hand-held visualizer to develop a fluorescence-based
visual readout. We also adapted a mobile phone application to further
simplify the interpretation of the results. Finally, we showed that
the reagents could be lyophilized to facilitate storage and distribution.
This detection platform represents a valuable addition to the toolbox
of cell-free, CRISPR-based biosensors, with great potential for in-field
deployment to detect non-nucleic acid small molecules.
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Affiliation(s)
- Ahmed Mahas
- Laboratory for Genome Engineering and Synthetic Biology, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Qiaochu Wang
- Laboratory for Genome Engineering and Synthetic Biology, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Tin Marsic
- Laboratory for Genome Engineering and Synthetic Biology, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Magdy M Mahfouz
- Laboratory for Genome Engineering and Synthetic Biology, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
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12
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Abril AG, Carrera M, Böhme K, Barros-Velázquez J, Calo-Mata P, Sánchez-Pérez A, Villa TG. Proteomic Characterization of Antibiotic Resistance in Listeria and Production of Antimicrobial and Virulence Factors. Int J Mol Sci 2021; 22:8141. [PMID: 34360905 PMCID: PMC8348566 DOI: 10.3390/ijms22158141] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/25/2021] [Accepted: 07/26/2021] [Indexed: 01/01/2023] Open
Abstract
Some Listeria species are important human and animal pathogens that can be found in contaminated food and produce a variety of virulence factors involved in their pathogenicity. Listeria strains exhibiting multidrug resistance are known to be progressively increasing and that is why continuous monitoring is needed. Effective therapy against pathogenic Listeria requires identification of the bacterial strain involved, as well as determining its virulence factors, such as antibiotic resistance and sensitivity. The present study describes the use of liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to do a global shotgun proteomics characterization for pathogenic Listeria species. This method allowed the identification of a total of 2990 non-redundant peptides, representing 2727 proteins. Furthermore, 395 of the peptides correspond to proteins that play a direct role in Listeria pathogenicity; they were identified as virulence factors, toxins and anti-toxins, or associated with either antibiotics (involved in antibiotic-related compounds production or resistance) or resistance to toxic substances. The proteomic repository obtained here can be the base for further research into pathogenic Listeria species and facilitate the development of novel therapeutics for these pathogens.
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Affiliation(s)
- Ana G. Abril
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Campus Sur 15782, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain;
| | - Mónica Carrera
- Marine Research Institute (IIM), Spanish National Research Council (CSIC), Eduardo Cabello 6, 36208 Vigo, Spain
| | - Karola Böhme
- Agroalimentary Technological Center of Lugo, Montirón 154, 27002 Lugo, Spain;
| | - Jorge Barros-Velázquez
- Departamento de Química Analítica, Nutrición y Bromatología, Área de Tecnología de los Alimentos, Facultad de Veterinaria, Campus Lugo, Universidad de Santiago de Compostela, 27002 Santiago de Compostela, Spain; (J.B.-V.); (P.C.-M.)
| | - Pilar Calo-Mata
- Departamento de Química Analítica, Nutrición y Bromatología, Área de Tecnología de los Alimentos, Facultad de Veterinaria, Campus Lugo, Universidad de Santiago de Compostela, 27002 Santiago de Compostela, Spain; (J.B.-V.); (P.C.-M.)
| | - Angeles Sánchez-Pérez
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW 2006, Australia;
| | - Tomás G. Villa
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Campus Sur 15782, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain;
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13
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Bahr G, González LJ, Vila AJ. Metallo-β-lactamases in the Age of Multidrug Resistance: From Structure and Mechanism to Evolution, Dissemination, and Inhibitor Design. Chem Rev 2021; 121:7957-8094. [PMID: 34129337 PMCID: PMC9062786 DOI: 10.1021/acs.chemrev.1c00138] [Citation(s) in RCA: 106] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Antimicrobial resistance is one of the major problems in current practical medicine. The spread of genes coding for resistance determinants among bacteria challenges the use of approved antibiotics, narrowing the options for treatment. Resistance to carbapenems, last resort antibiotics, is a major concern. Metallo-β-lactamases (MBLs) hydrolyze carbapenems, penicillins, and cephalosporins, becoming central to this problem. These enzymes diverge with respect to serine-β-lactamases by exhibiting a different fold, active site, and catalytic features. Elucidating their catalytic mechanism has been a big challenge in the field that has limited the development of useful inhibitors. This review covers exhaustively the details of the active-site chemistries, the diversity of MBL alleles, the catalytic mechanism against different substrates, and how this information has helped developing inhibitors. We also discuss here different aspects critical to understand the success of MBLs in conferring resistance: the molecular determinants of their dissemination, their cell physiology, from the biogenesis to the processing involved in the transit to the periplasm, and the uptake of the Zn(II) ions upon metal starvation conditions, such as those encountered during an infection. In this regard, the chemical, biochemical and microbiological aspects provide an integrative view of the current knowledge of MBLs.
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Affiliation(s)
- Guillermo Bahr
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Lisandro J. González
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
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14
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Balogh RK, Németh E, Jones NC, Hoffmann SV, Jancsó A, Gyurcsik B. A study on the secondary structure of the metalloregulatory protein CueR: effect of pH, metal ions and DNA. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:491-500. [PMID: 33907862 DOI: 10.1007/s00249-021-01539-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/13/2021] [Accepted: 04/14/2021] [Indexed: 11/30/2022]
Abstract
The response of CueR towards environmental changes in solution was investigated. CueR is a bacterial metal ion selective transcriptional metalloregulator protein, which controls the concentration of copper ions in the cell. Although several articles have been devoted to the discussion of the structural and functional features of this protein, CueR has not previously been extensively characterized in solution. Here, we studied the effect of change in pH, temperature, and the presence of specific or non-specific binding partners on the secondary structure of CueR with circular dichroism (CD) spectroscopy. A rather peculiar reversible pH-dependent secondary structure transformation was observed, elucidated and supplemented with pKa estimation by PROPKA and CpHMD simulations suggesting an important role of His(76) and His(94) in this process. CD experiments revealed that the presence of DNA prevents this structural switch, suggesting that DNA locks CueR in the α-helical-rich form. In contrast to the non-cognate metal ions HgII, CdII and ZnII, the presence of the cognate AgI ion affects the secondary structure of CueR, most probably by stabilizing the metal ion and DNA-binding domains of the protein.
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Affiliation(s)
- Ria K Balogh
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, 6720, Hungary
| | - Eszter Németh
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, 6720, Hungary.,Institute of Enzymology, Genome Stability Research Group, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Nykola C Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus C, Denmark
| | - Søren Vrønning Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus C, Denmark
| | - Attila Jancsó
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, 6720, Hungary
| | - Béla Gyurcsik
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, 6720, Hungary.
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15
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Rodríguez-Serrano AF, Hsing IM. Allosteric Regulation of DNA Circuits Enables Minimal and Rapid Biosensors of Small Molecules. ACS Synth Biol 2021; 10:371-378. [PMID: 33481567 DOI: 10.1021/acssynbio.0c00545] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Detection of environmental pollutants is crucial to safeguard ecological and public health. Here, we report a modular biosensing approach for the detection of contaminants based on the regulation of a minimal DNA signal amplifier and transducer circuit by allosteric transcription factors and their cognate ligands. We leverage the competition between allosteric proteins and an endonuclease to modulate cascade toehold-mediated strand displacement reactions, which are triggered in the presence of specific effectors and sustained by the endonuclease. We built two optical biosensors for the detection of tetracyclines and macrolides in water using repressors TetR and MphR, respectively. We demonstrate that our minimal, fast, and single-step biosensors can successfully detect antibiotics in nanomolar levels and apply them to report the presence of spiked-in antibiotics in water samples in a matter of minutes, suggesting great potential for monitoring of water contaminants.
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Affiliation(s)
- Alan F. Rodríguez-Serrano
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - I-Ming Hsing
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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16
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Abril AG, Carrera M, Böhme K, Barros-Velázquez J, Rama JLR, Calo-Mata P, Sánchez-Pérez A, Villa TG. Proteomic Characterization of Antibiotic Resistance, and Production of Antimicrobial and Virulence Factors in Streptococcus Species Associated with Bovine Mastitis. Could Enzybiotics Represent Novel Therapeutic Agents Against These Pathogens? Antibiotics (Basel) 2020; 9:antibiotics9060302. [PMID: 32512932 PMCID: PMC7344566 DOI: 10.3390/antibiotics9060302] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 05/28/2020] [Accepted: 06/03/2020] [Indexed: 01/31/2023] Open
Abstract
Streptococcus spp. are major mastitis pathogens present in dairy products, which produce a variety of virulence factors that are involved in streptococcal pathogenicity. These include neuraminidase, pyrogenic exotoxin, and M protein, and in addition they might produce bacteriocins and antibiotic-resistance proteins. Unjustifiable misuse of antimicrobials has led to an increase in antibiotic-resistant bacteria present in foodstuffs. Identification of the mastitis-causing bacterial strain, as well as determining its antibiotic resistance and sensitivity is crucial for effective therapy. The present work focused on the LC–ESI–MS/MS (liquid chromatography–electrospray ionization tandem mass spectrometry) analysis of tryptic digestion peptides from mastitis-causing Streptococcus spp. isolated from milk. A total of 2706 non-redundant peptides belonging to 2510 proteins was identified and analyzed. Among them, 168 peptides were determined, representing proteins that act as virulence factors, toxins, anti-toxins, provide resistance to antibiotics that are associated with the production of lantibiotic-related compounds, or play a role in the resistance to toxic substances. Protein comparisons with the NCBI database allowed the identification of 134 peptides as specific to Streptococcus spp., while two peptides (EATGNQNISPNLTISNAQLNLEDKNK and DLWC*NM*IIAAK) were found to be species-specific to Streptococcus dysgalactiae. This proteomic repository might be useful for further studies and research work, as well as for the development of new therapeutics for the mastitis-causing Streptococcus strains.
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Affiliation(s)
- Ana G. Abril
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Campus Sur 15782, Universidad de Santiago de Compostela, 15705 Santiago de Compostela, Spain; (A.G.A.); (J.-L.R.R.)
| | - Mónica Carrera
- Marine Research Institute (IIM), Spanish National Research Council (CSIC), Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain;
| | - Karola Böhme
- Agroalimentary Technological Center of Lugo, Montirón 154, 27002 Lugo, Spain;
| | - Jorge Barros-Velázquez
- Departamento de Química Analítica, Nutrición y Bromatología, Area de Tecnología de los Alimentos, Facultad de Veterinaria, Campus Lugo, Universidad de Santiago de Compostela, 27002 Lugo, Spain; (J.B.-V.); (P.C.-M.)
| | - José-Luis R. Rama
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Campus Sur 15782, Universidad de Santiago de Compostela, 15705 Santiago de Compostela, Spain; (A.G.A.); (J.-L.R.R.)
| | - Pilar Calo-Mata
- Departamento de Química Analítica, Nutrición y Bromatología, Area de Tecnología de los Alimentos, Facultad de Veterinaria, Campus Lugo, Universidad de Santiago de Compostela, 27002 Lugo, Spain; (J.B.-V.); (P.C.-M.)
| | - Angeles Sánchez-Pérez
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW 2006, Australia;
| | - Tomás G. Villa
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Campus Sur 15782, Universidad de Santiago de Compostela, 15705 Santiago de Compostela, Spain; (A.G.A.); (J.-L.R.R.)
- Correspondence:
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17
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Baksh KA, Zamble DB. Allosteric control of metal-responsive transcriptional regulators in bacteria. J Biol Chem 2020; 295:1673-1684. [PMID: 31857375 PMCID: PMC7008368 DOI: 10.1074/jbc.rev119.011444] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Many transition metals are essential trace nutrients for living organisms, but they are also cytotoxic in high concentrations. Bacteria maintain the delicate balance between metal starvation and toxicity through a complex network of metal homeostasis pathways. These systems are coordinated by the activities of metal-responsive transcription factors-also known as metal-sensor proteins or metalloregulators-that are tuned to sense the bioavailability of specific metals in the cell in order to regulate the expression of genes encoding proteins that contribute to metal homeostasis. Metal binding to a metalloregulator allosterically influences its ability to bind specific DNA sequences through a variety of intricate mechanisms that lie on a continuum between large conformational changes and subtle changes in internal dynamics. This review summarizes recent advances in our understanding of how metal sensor proteins respond to intracellular metal concentrations. In particular, we highlight the allosteric mechanisms used for metal-responsive regulation of several prokaryotic single-component metalloregulators, and we briefly discuss current open questions of how metalloregulators function in bacterial cells. Understanding the regulation and function of metal-responsive transcription factors is a fundamental aspect of metallobiochemistry and is important for gaining insights into bacterial growth and virulence.
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Affiliation(s)
- Karina A Baksh
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Deborah B Zamble
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
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18
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Mazhar SH, Herzberg M, Ben Fekih I, Zhang C, Bello SK, Li YP, Su J, Xu J, Feng R, Zhou S, Rensing C. Comparative Insights Into the Complete Genome Sequence of Highly Metal Resistant Cupriavidus metallidurans Strain BS1 Isolated From a Gold-Copper Mine. Front Microbiol 2020; 11:47. [PMID: 32117100 PMCID: PMC7019866 DOI: 10.3389/fmicb.2020.00047] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/10/2020] [Indexed: 12/12/2022] Open
Abstract
The highly heavy metal resistant strain Cupriavidus metallidurans BS1 was isolated from the Zijin gold–copper mine in China. This was of particular interest since the extensively studied, closely related strain, C. metallidurans CH34 was shown to not be only highly heavy metal resistant but also able to reduce metal complexes and biomineralizing them into metallic nanoparticles including gold nanoparticles. After isolation, C. metallidurans BS1 was characterized and complete genome sequenced using PacBio and compared to CH34. Many heavy metal resistance determinants were identified and shown to have wide-ranging similarities to those of CH34. However, both BS1 and CH34 displayed extensive genome plasticity, probably responsible for significant differences between those strains. BS1 was shown to contain three prophages, not present in CH34, that appear intact and might be responsible for shifting major heavy metal resistance determinants from plasmid to chromid (CHR2) in C. metallidurans BS1. Surprisingly, the single plasmid – pBS1 (364.4 kbp) of BS1 contains only a single heavy metal resistance determinant, the czc determinant representing RND-type efflux system conferring resistance to cobalt, zinc and cadmium, shown here to be highly similar to that determinant located on pMOL30 in C. metallidurans CH34. However, in BS1 another homologous czc determinant was identified on the chromid, most similar to the czc determinant from pMOL30 in CH34. Other heavy metal resistance determinants such as cnr and chr determinants, located on megaplasmid pMOL28 in CH34, were shown to be adjacent to the czc determinant on chromid (CHR2) in BS1. Additionally, other heavy metal resistance determinants such as pbr, cop, sil, and ars were located on the chromid (CHR2) and not on pBS1 in BS1. A diverse range of genomic rearrangements occurred in this strain, isolated from a habitat of constant exposure to high concentrations of copper, gold and other heavy metals. In contrast, the megaplasmid in BS1 contains mostly genes encoding unknown functions, thus might be more of an evolutionary playground where useful genes could be acquired by horizontal gene transfer and possibly reshuffled to help C. metallidurans BS1 withstand the intense pressure of extreme concentrations of heavy metals in its environment.
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Affiliation(s)
- Sohaib H Mazhar
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Ibtissem Ben Fekih
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Chenkang Zhang
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Suleiman Kehinde Bello
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuan Ping Li
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junming Su
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junqiang Xu
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Renwei Feng
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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19
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Lee W, Kim H, Jang G, Kim BG, Yoon Y. Antimony sensing whole-cell bioreporters derived from ArsR genetic engineering. Appl Microbiol Biotechnol 2020; 104:2691-2699. [PMID: 32002600 DOI: 10.1007/s00253-020-10413-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/15/2020] [Accepted: 01/24/2020] [Indexed: 12/01/2022]
Abstract
Despite the known hazardous effects of antimony (Sb) on human health, Sb monitoring biosensors have not been as actively investigated as arsenic (As) biosensors. Whole-cell bioreporters (WCBs) employing an arsenic-responsive operon and a regulatory protein (ArsR) are reportedly capable of monitoring arsenite, arsenate, and antimonite. However, the potential of WCBs as Sb biosensors has been largely ignored. Here, the metal-binding site of ArsR (sequenced as ELCVCDLCTA from amino acid number 30 to 39) was modified via genetic engineering to enhance Sb specificity. By relocating cysteine residues and introducing point mutations, nine ArsR mutants were generated and tested for metal(loid) ion specificity. The Sb specificity of WCBs was enhanced by the C37S/A39C and L36C/C37S mutations on the As binding site of ArsR. Additionally, WCBs with other ArsR mutants exhibited new target sensing capabilities toward Cd and Pb. Although further research is required to enhance the specificity and sensitivity of WCBs and to broaden their practical applications, our proposed strategy based on genetic engineering of regulatory proteins provides a valuable basis to generate WCBs to monitor novel targets.
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Affiliation(s)
- Woonwoo Lee
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, Republic of Korea
| | - Hyojin Kim
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, Republic of Korea
| | - Geupil Jang
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Bong-Gyu Kim
- Department of Forest Resources, Gyeongnam National University of Science and Technology, Jinju, 52725, Republic of Korea
| | - Youngdae Yoon
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, Republic of Korea.
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20
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EfrEF and the Transcription Regulator ChlR Are Required for Chlorhexidine Stress Response in Enterococcus faecalis V583. Antimicrob Agents Chemother 2018; 62:AAC.00267-18. [PMID: 29610200 PMCID: PMC5971576 DOI: 10.1128/aac.00267-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 03/16/2018] [Indexed: 12/28/2022] Open
Abstract
Enterococcus faecalis is an opportunistic pathogen and leading cause of health care-associated infections. Daily chlorhexidine gluconate (CHG) bathing of patients is generally regarded as an effective strategy to reduce the occurrence of health care-associated infections. It is likely that E. faecalis is frequently exposed to inhibitory and subinhibitory concentrations of CHG in clinical settings. The goal of this study was to investigate how the vancomycin-resistant strain E. faecalis V583 transcriptionally responds to and tolerates stress from CHG. We used transcriptome (microarray) analysis to identify genes upregulated by E. faecalis V583 in response to CHG. The genes efrE (EF2226) and efrF (EF2227), encoding a heterodimeric ABC transport system, were the most highly upregulated genes. efrEF expression was induced by CHG at concentrations several 2-fold dilutions below the MIC. Deletion of efrEF increased E. faecalis V583 susceptibility to CHG. We found that ChlR, a MerR-like regulator encoded by a sequence upstream of efrEF, mediated the CHG-dependent upregulation of efrEF, and deletion of chlR also increased chlorhexidine susceptibility. Overall, our study gives insight into E. faecalis stress responses to a commonly used antiseptic.
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21
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Raj R, Das S. Development and application of anticancer fluorescent CdS nanoparticles enriched Lactobacillus bacteria as therapeutic microbots for human breast carcinoma. Appl Microbiol Biotechnol 2017; 101:5439-5451. [PMID: 28455616 DOI: 10.1007/s00253-017-8298-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/06/2017] [Accepted: 04/11/2017] [Indexed: 01/21/2023]
Abstract
Applications of probiotic bacteria and nanoparticles (NPs) as therapeutic agents have great importance. This study demonstrates a combinatorial approach of both the probiotic Lactobacillus spp. (Lactobacillus fermentum and Lactobacillus plantarum) with fluorescent cadmium sulfide (CdS) NPs as therapeutic agents to target MCF-7 cancer cells (human breast cancer cells). In this study, facultative anaerobic Lactobacillus was successfully used as a vehicle to transport NPs into MCF-7 cancer cells. The cell viability assay and invasion study along with confocal and field emission scanning electron microscopy (FESEM) confirmed the release of payload (CdS NPs) into cytoplasm without any external stimuli. The biosynthesized CdS NPs of ∼22 nm were characterized by FESEM, transmission electron microscopy (TEM), atomic force microscopy (AFM), and fluorescence spectroscopy. The bacteria-NPs (microbots) interaction was investigated by growth curve studies, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), FESEM, energy dispersive X-ray spectroscopy (EDX), and fluorescence and confocal microscopy. This alternative approach showed an approved and inexpensive delivering mode of specific functional cargos or therapeutic agents into the cancer cells.
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Affiliation(s)
- Ritu Raj
- Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769008, India
| | - Surajit Das
- Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769008, India.
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22
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Bush MJ, Chandra G, Findlay KC, Buttner MJ. Multi-layered inhibition of Streptomyces development: BldO is a dedicated repressor of whiB. Mol Microbiol 2017; 104:700-711. [PMID: 28271577 PMCID: PMC5485038 DOI: 10.1111/mmi.13663] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/04/2017] [Indexed: 02/07/2023]
Abstract
BldD‐(c‐di‐GMP) sits on top of the regulatory network that controls differentiation in Streptomyces, repressing a large regulon of developmental genes when the bacteria are growing vegetatively. In this way, BldD functions as an inhibitor that blocks the initiation of sporulation. Here, we report the identification and characterisation of BldO, an additional developmental repressor that acts to sustain vegetative growth and prevent entry into sporulation. However, unlike the pleiotropic regulator BldD, we show that BldO functions as the dedicated repressor of a single key target gene, whiB, and that deletion of bldO or constitutive expression of whiB is sufficient to induce precocious hypersporulation.
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Affiliation(s)
- Matthew J Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Kim C Findlay
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Mark J Buttner
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
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Gomez RL, Jose L, Ramachandran R, Raghunandanan S, Muralikrishnan B, Johnson JB, Sivakumar KC, Mundayoor S, Kumar RA. The multiple stress responsive transcriptional regulator Rv3334 of Mycobacterium tuberculosis is an autorepressor and a positive regulator of kstR. FEBS J 2016; 283:3056-71. [PMID: 27334653 DOI: 10.1111/febs.13791] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 06/12/2016] [Accepted: 06/22/2016] [Indexed: 11/26/2022]
Abstract
Rv3334 protein of Mycobacterium tuberculosis belongs to the MerR family of transcriptional regulators and is upregulated during hypoxia and other stress conditions. Employing GFP reporter constructs, mobility shift assays and ChIP assays, we demonstrate that Rv3334 binds to its own promoter and acts as an autorepressor. We were able to locate a 22 bp palindrome in its promoter that we show to be the cognate binding sequence of Rv3334. Using chase experiments, we could conclusively prove the requirement of this palindrome for Rv3334 binding. Recombinant Rv3334 readily formed homodimers in vitro, which could be necessary for its transcriptional regulatory role in vivo. Although the DNA-binding activity of the protein was abrogated by the presence of certain divalent metal cations, the homodimer formation remained unaffected. In silico predictions and subsequent assays using GFP reporter constructs and mobility shift assays revealed that the expression of ketosteroid regulator gene (kstR), involved in lipid catabolism, is positively regulated by Rv3334. ChIP assays with aerobically grown M. tuberculosis as well as dormant bacteria unambiguously prove that Rv3334 specifically upregulates expression of kstR during dormancy. Our study throws light on the possible role of Rv3334 as a master regulator of lipid catabolism during hypoxia-induced dormancy.
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Affiliation(s)
- Roshna Lawrence Gomez
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Leny Jose
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Ranjit Ramachandran
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Sajith Raghunandanan
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Balaji Muralikrishnan
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - John Bernet Johnson
- Viral Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | | | - Sathish Mundayoor
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Ramakrishnan Ajay Kumar
- Mycobacterium Research Group, Tropical Disease Biology Division, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
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Szunyogh D, Szokolai H, Thulstrup PW, Larsen FH, Gyurcsik B, Christensen NJ, Stachura M, Hemmingsen L, Jancsó A. Specificity of the Metalloregulator CueR for Monovalent Metal Ions: Possible Functional Role of a Coordinated Thiol? Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201508555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Dániel Szunyogh
- MTA‐SZTE Bioinorganic Chemistry Research Group, Dóm tér 7, 6720 Szeged (Hungary)
| | - Hajnalka Szokolai
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720 Szeged (Hungary)
| | - Peter W. Thulstrup
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)
| | - Flemming H. Larsen
- Department of Food Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C (Denmark)
| | - Béla Gyurcsik
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720 Szeged (Hungary)
| | - Niels Johan Christensen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)
| | - Monika Stachura
- ISOLDE‐CERN, 1211 Geneva 23 (Switzerland)
- TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada)
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)
| | - Attila Jancsó
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720 Szeged (Hungary)
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Szunyogh D, Szokolai H, Thulstrup PW, Larsen FH, Gyurcsik B, Christensen NJ, Stachura M, Hemmingsen L, Jancsó A. Specificity of the Metalloregulator CueR for Monovalent Metal Ions: Possible Functional Role of a Coordinated Thiol? Angew Chem Int Ed Engl 2015; 54:15756-61. [PMID: 26563985 DOI: 10.1002/anie.201508555] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Indexed: 11/12/2022]
Abstract
Metal-ion-responsive transcriptional regulators within the MerR family effectively discriminate between mono- and divalent metal ions. Herein we address the origin of the specificity of the CueR protein for monovalent metal ions. Several spectroscopic techniques were employed to study Ag(I) , Zn(II) , and Hg(II) binding to model systems encompassing the metal-ion-binding loop of CueR from E. coli and V. cholerae. In the presence of Ag(I) , a conserved cysteine residue displays a pKa value for deprotonation of the thiol that is close to the physiological pH value. This property is only observed with the monovalent metal ion. Quantum chemically optimized structures of the CueR metal site with Cys 112 protonated demonstrate that the conserved Ser 77 backbone carbonyl oxygen atom from the other monomer of the homodimer is "pulled" towards the metal site. A common allosteric mechanism of the metalloregulatory members of the MerR family is proposed. For CueR, the mechanism relies on the protonation of Cys 112.
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Affiliation(s)
- Dániel Szunyogh
- MTA-SZTE Bioinorganic Chemistry Research Group, Dóm tér 7, 6720 Szeged (Hungary)
| | - Hajnalka Szokolai
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720 Szeged (Hungary)
| | - Peter W Thulstrup
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)
| | - Flemming H Larsen
- Department of Food Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C (Denmark)
| | - Béla Gyurcsik
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720 Szeged (Hungary)
| | - Niels Johan Christensen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)
| | - Monika Stachura
- ISOLDE-CERN, 1211 Geneva 23 (Switzerland).,TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 (Canada)
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark).
| | - Attila Jancsó
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720 Szeged (Hungary).
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Srinivasan VB, Venkataramaiah M, Mondal A, Rajamohan G. Functional Characterization of AbeD, an RND-Type Membrane Transporter in Antimicrobial Resistance in Acinetobacter baumannii. PLoS One 2015; 10:e0141314. [PMID: 26496475 PMCID: PMC4619830 DOI: 10.1371/journal.pone.0141314] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 10/07/2015] [Indexed: 01/17/2023] Open
Abstract
Background Acinetobacter baumannii is becoming an increasing menace in health care settings especially in the intensive care units due to its ability to withstand adverse environmental conditions and exhibit innate resistance to different classes of antibiotics. Here we describe the biological contributions of abeD, a novel membrane transporter in bacterial stress response and antimicrobial resistance in A. baumannii. Results The abeD mutant displayed ~ 3.37 fold decreased survival and >5-fold reduced growth in hostile osmotic (0.25 M; NaCl) and oxidative (2.631 μM–6.574 μM; H2O2) stress conditions respectively. The abeD inactivated cells displayed increased susceptibility to ceftriaxone, gentamicin, rifampicin and tobramycin (~ 4.0 fold). The mutant displayed increased sensitivity to the hospital-based disinfectant benzalkonium chloride (~3.18-fold). In Caenorhabditis elegans model, the abeD mutant exhibited (P<0.01) lower virulence capability. Binding of SoxR on the regulatory fragments of abeD provide strong evidence for the involvement of SoxR system in regulating the expression of abeD in A. baumannii. Conclusion This study demonstrates the contributions of membrane transporter AbeD in bacterial physiology, stress response and antimicrobial resistance in A. baumannii for the first time.
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Affiliation(s)
- Vijaya Bharathi Srinivasan
- Council of Scientific Industrial Research- Institute of Microbial Technology, Sector 39 A, Chandigarh-160036, India
| | - Manjunath Venkataramaiah
- Council of Scientific Industrial Research- Institute of Microbial Technology, Sector 39 A, Chandigarh-160036, India
| | - Amitabha Mondal
- Council of Scientific Industrial Research- Institute of Microbial Technology, Sector 39 A, Chandigarh-160036, India
| | - Govindan Rajamohan
- Council of Scientific Industrial Research- Institute of Microbial Technology, Sector 39 A, Chandigarh-160036, India
- * E-mail:
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Metalloregulator CueR biases RNA polymerase's kinetic sampling of dead-end or open complex to repress or activate transcription. Proc Natl Acad Sci U S A 2015; 112:13467-72. [PMID: 26483469 DOI: 10.1073/pnas.1515231112] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Metalloregulators respond to metal ions to regulate transcription of metal homeostasis genes. MerR-family metalloregulators act on σ(70)-dependent suboptimal promoters and operate via a unique DNA distortion mechanism in which both the apo and holo forms of the regulators bind tightly to their operator sequence, distorting DNA structure and leading to transcription repression or activation, respectively. It remains unclear how these metalloregulator-DNA interactions are coupled dynamically to RNA polymerase (RNAP) interactions with DNA for transcription regulation. Using single-molecule FRET, we study how the copper efflux regulator (CueR)--a Cu(+)-responsive MerR-family metalloregulator--modulates RNAP interactions with CueR's cognate suboptimal promoter PcopA, and how RNAP affects CueR-PcopA interactions. We find that RNAP can form two noninterconverting complexes at PcopA in the absence of nucleotides: a dead-end complex and an open complex, constituting a branched interaction pathway that is distinct from the linear pathway prevalent for transcription initiation at optimal promoters. Capitalizing on this branched pathway, CueR operates via a "biased sampling" instead of "dynamic equilibrium shifting" mechanism in regulating transcription initiation; it modulates RNAP's binding-unbinding kinetics, without allowing interconversions between the dead-end and open complexes. Instead, the apo-repressor form reinforces the dominance of the dead-end complex to repress transcription, and the holo-activator form shifts the interactions toward the open complex to activate transcription. RNAP, in turn, locks CueR binding at PcopA into its specific binding mode, likely helping amplify the differences between apo- and holo-CueR in imposing DNA structural changes. Therefore, RNAP and CueR work synergistically in regulating transcription.
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Monsieurs P, Hobman J, Vandenbussche G, Mergeay M, Van Houdt R. Response of Cupriavidus metallidurans CH34 to Metals. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/978-3-319-20594-6_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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29
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Szunyogh D, Gyurcsik B, Larsen FH, Stachura M, Thulstrup PW, Hemmingsen L, Jancsó A. Zn(II) and Hg(II) binding to a designed peptide that accommodates different coordination geometries. Dalton Trans 2015; 44:12576-88. [PMID: 26040991 DOI: 10.1039/c5dt00945f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Designed metal ion binding peptides offer a variety of applications in both basic science as model systems of more complex metalloproteins, and in biotechnology, e.g. in bioremediation of toxic metal ions, biomining or as artificial enzymes. In this work a peptide (HS: Ac-SCHGDQGSDCSI-NH2) has been specifically designed for binding of both Zn(II) and Hg(II), i.e. metal ions with different preferences in terms of coordination number, coordination geometry, and to some extent ligand composition. It is demonstrated that HS accommodates both metal ions, and the first coordination sphere, metal ion exchange between peptides, and speciation are characterized as a function of pH using UV-absorption-, synchrotron radiation CD-, (1)H-NMR-, and PAC-spectroscopy as well as potentiometry. Hg(II) binds to the peptide with very high affinity in a {HgS2} coordination geometry, bringing together the two cysteinates close to each end of the peptide in a loop structure. Despite the high affinity, Hg(II) is kinetically labile, exchanging between peptides on the subsecond timescale, as indicated by line broadening in (1)H-NMR. The Zn(II)-HS system displays more complex speciation, involving monomeric species with coordinating cysteinates, histidine, and a solvent water molecule, as well as HS-Zn(II)-HS complexes. In summary, the HS peptide displays conformational flexibility, contains many typical metal ion binding groups, and is able to accommodate metal ions with different structural and ligand preferences with high affinity. As such, the HS peptide may be a scaffold offering binding of a variety of metal ions, and potentially serve for metal ion sequestration in biotechnological applications.
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Affiliation(s)
- Dániel Szunyogh
- MTA-SZTE Bioinorganic Chemistry Research Group, Dóm tér 7, Szeged, H-6720, Hungary
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Coordinated zinc homeostasis is essential for the wild-type virulence of Brucella abortus. J Bacteriol 2015; 197:1582-91. [PMID: 25691532 DOI: 10.1128/jb.02543-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/11/2015] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED Metal homeostasis in bacterial cells is a highly regulated process requiring intricately coordinated import and export, as well as precise sensing of intracellular metal concentrations. The uptake of zinc (Zn) has been linked to the virulence of Brucella abortus; however, the capacity of Brucella strains to sense Zn levels and subsequently coordinate Zn homeostasis has not been described. Here, we show that expression of the genes encoding the zinc uptake system ZnuABC is negatively regulated by the Zn-sensing Fur family transcriptional regulator, Zur, by direct interactions between Zur and the promoter region of znuABC. Moreover, the MerR-type regulator, ZntR, controls the expression of the gene encoding the Zn exporter ZntA by binding directly to its promoter. Deletion of zur or zntR alone did not result in increased zinc toxicity in the corresponding mutants; however, deletion of zntA led to increased sensitivity to Zn but not to other metals, such as Cu and Ni, suggesting that ZntA is a Zn-specific exporter. Strikingly, deletion of zntR resulted in significant attenuation of B. abortus in a mouse model of chronic infection, and subsequent experiments revealed that overexpression of zntA in the zntR mutant is the molecular basis for its decreased virulence. IMPORTANCE The importance of zinc uptake for Brucella pathogenesis has been demonstrated previously, but to date, there has been no description of how overall zinc homeostasis is maintained and genetically controlled in the brucellae. The present work defines the predominant zinc export system, as well as the key genetic regulators of both zinc uptake and export in Brucella abortus. Moreover, the data show the importance of precise coordination of the zinc homeostasis systems as disregulation of some elements of these systems leads to the attenuation of Brucella virulence in a mouse model. Overall, this study advances our understanding of the essential role of zinc in the pathogenesis of intracellular bacteria.
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A single serine residue determines selectivity to monovalent metal ions in metalloregulators of the MerR family. J Bacteriol 2015; 197:1606-13. [PMID: 25691529 DOI: 10.1128/jb.02565-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/11/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED MerR metalloregulators alleviate toxicity caused by an excess of metal ions, such as copper, zinc, mercury, lead, cadmium, silver, or gold, by triggering the expression of specific efflux or detoxification systems upon metal detection. The sensor protein binds the inducer metal ion by using two conserved cysteine residues at the C-terminal metal-binding loop (MBL). Divalent metal ion sensors, such as MerR and ZntR, require a third cysteine residue, located at the beginning of the dimerization (α5) helix, for metal coordination, while monovalent metal ion sensors, such as CueR and GolS, have a serine residue at this position. This serine residue was proposed to provide hydrophobic and steric restrictions to privilege the binding of monovalent metal ions. Here we show that the presence of alanine at this position does not modify the activation pattern of monovalent metal sensors. In contrast, GolS or CueR mutant sensors with a substitution of cysteine for the serine residue respond to monovalent metal ions or Hg(II) with high sensitivities. Furthermore, in a mutant deleted of the Zn(II) exporter ZntA, they also trigger the expression of their target genes in response to either Zn(II), Cd(II), Pb(II), or Co(II). IMPORTANCE Specificity in a stressor's recognition is essential for mounting an appropriate response. MerR metalloregulators trigger the expression of specific resistance systems upon detection of heavy metal ions. Two groups of these metalloregulators can be distinguished, recognizing either +1 or +2 metal ions, depending on the presence of a conserved serine in the former or a cysteine in the latter. Here we demonstrate that the serine residue in monovalent metal ion sensors excludes divalent metal ion detection, as its replacement by cysteine renders a pan-metal ion sensor. Our results indicate that the spectrum of signals detected by these sensors is determined not only by the metal-binding ligand availability but also by the metal-binding cavity flexibility.
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Abstract
The most common prokaryotic signal transduction mechanisms are the one-component systems in which a single polypeptide contains both a sensory domain and a DNA-binding domain. Among the >20 classes of one-component systems, the TetR family of regulators (TFRs) are widely associated with antibiotic resistance and the regulation of genes encoding small-molecule exporters. However, TFRs play a much broader role, controlling genes involved in metabolism, antibiotic production, quorum sensing, and many other aspects of prokaryotic physiology. There are several well-established model systems for understanding these important proteins, and structural studies have begun to unveil the mechanisms by which they bind DNA and recognize small-molecule ligands. The sequences for more than 200,000 TFRs are available in the public databases, and genomics studies are identifying their target genes. Three-dimensional structures have been solved for close to 200 TFRs. Comparison of these structures reveals a common overall architecture of nine conserved α helices. The most important open question concerning TFR biology is the nature and diversity of their ligands and how these relate to the biochemical processes under their control.
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Ishchukov I, Wu Y, Van Puyvelde S, Vanderleyden J, Marchal K. Inferring the relation between transcriptional and posttranscriptional regulation from expression compendia. BMC Microbiol 2014; 14:14. [PMID: 24467879 PMCID: PMC3948049 DOI: 10.1186/1471-2180-14-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 01/09/2014] [Indexed: 12/21/2022] Open
Abstract
Background Publicly available expression compendia that measure both mRNAs and sRNAs provide a promising resource to simultaneously infer the transcriptional and the posttranscriptional network. To maximally exploit the information contained in such compendia, we propose an analysis flow that combines publicly available expression compendia and sequence-based predictions to infer novel sRNA-target interactions and to reconstruct the relation between the sRNA and the transcriptional network. Results We relied on module inference to construct modules of coexpressed genes (sRNAs). TFs and sRNAs were assigned to these modules using the state-of-the-art inference techniques LeMoNe and Context Likelihood of Relatedness (CLR). Combining these expressions with sequence-based sRNA-target interactions allowed us to predict 30 novel sRNA-target interactions comprising 14 sRNAs. Our results highlight the role of the posttranscriptional network in finetuning the transcriptional regulation, e.g. by intra-operonic regulation. Conclusion In this work we show how strategies that combine expression information with sequence-based predictions can help unveiling the intricate interaction between the transcriptional and the posttranscriptional network in prokaryotic model systems.
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Affiliation(s)
| | | | | | | | - Kathleen Marchal
- Center of Microbial and Plant Genetics, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
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34
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Zhang H, Sheng Y, Wu Q, Liu A, Lu Y, Yin Z, Cao Y, Zeng W, Ouyang Q. Rational design of a biosensor circuit with semi-log dose-response function in Escherichia coli. QUANTITATIVE BIOLOGY 2013. [DOI: 10.1007/s40484-013-0020-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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35
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Chen P, Keller AM, Joshi CP, Martell DJ, Andoy NM, Benítez JJ, Chen TY, Santiago AG, Yang F. Single-molecule dynamics and mechanisms of metalloregulators and metallochaperones. Biochemistry 2013; 52:7170-83. [PMID: 24053279 DOI: 10.1021/bi400597v] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Understanding how cells regulate and transport metal ions is an important goal in the field of bioinorganic chemistry, a frontier research area that resides at the interface of chemistry and biology. This Current Topic reviews recent advances from the authors' group in using single-molecule fluorescence imaging techniques to identify the mechanisms of metal homeostatic proteins, including metalloregulators and metallochaperones. It emphasizes the novel mechanistic insights into how dynamic protein-DNA and protein-protein interactions offer efficient pathways via which MerR-family metalloregulators and copper chaperones can fulfill their functions. This work also summarizes other related single-molecule studies of bioinorganic systems and provides an outlook toward single-molecule imaging of metalloprotein functions in living cells.
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Affiliation(s)
- Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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36
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Decker KB, Hinton DM. Transcription Regulation at the Core: Similarities Among Bacterial, Archaeal, and Eukaryotic RNA Polymerases. Annu Rev Microbiol 2013; 67:113-39. [DOI: 10.1146/annurev-micro-092412-155756] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kimberly B. Decker
- Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Deborah M. Hinton
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892;
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Dissecting the metal selectivity of MerR monovalent metal ion sensors in Salmonella. J Bacteriol 2013; 195:3084-92. [PMID: 23645605 DOI: 10.1128/jb.00153-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Two homologous transcription factors, CueR and GolS, that belong to the MerR metalloregulatory family are responsible for Salmonella Cu and Au sensing and resistance, respectively. They share similarities not only in their sequences, but also in their target transcription binding sites. While CueR responds similarly to Au, Ag, or Cu to induce the expression of its target genes, GolS shows higher activation by Au than by Ag or Cu. We showed that the ability of GolS to distinguish Au from Cu resides in the metal-binding loop motif. Here, we identify the amino acids within the motif that determine in vivo metal selectivity. We show that residues at positions 113 and 118 within the metal-binding loop are the main contributors to metal selectivity. The presence of a Pro residue at position 113 favors the detection of Cu, while the presence of Pro at position 118 disfavors it. Our results highlight the molecular bases that allow these regulators to coordinate the correct metal ion directing the response to a particular metal injury.
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Direct substitution and assisted dissociation pathways for turning off transcription by a MerR-family metalloregulator. Proc Natl Acad Sci U S A 2012; 109:15121-6. [PMID: 22949686 DOI: 10.1073/pnas.1208508109] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Metalloregulators regulate transcription in response to metal ions. Many studies have provided insights into how transcription is activated upon metal binding by MerR-family metalloregulators. In contrast, how transcription is turned off after activation is unclear. Turning off transcription promptly is important, however, as the cells would not want to continue expressing metal resistance genes and thus waste energy after metal stress is relieved. Using single-molecule FRET measurements we studied the dynamic interactions of the copper efflux regulator (CueR), a Cu(+)-responsive MerR-family metalloregulator, with DNA. Besides quantifying its DNA binding and unbinding kinetics, we discovered that CueR spontaneously flips its binding orientation at the recognition site. CueR also has two different binding modes, corresponding to interactions with specific and nonspecific DNA sequences, which would facilitate recognition localization. Most strikingly, a CueR molecule coming from solution can directly substitute for a DNA-bound CueR or assist the dissociation of the incumbent CueR, both of which are unique examples for any DNA-binding protein. The kinetics of the direct protein substitution and assisted dissociation reactions indicate that these two unique processes can provide efficient pathways to replace a DNA-bound holo-CueR with apo-CueR, thus turning off transcription promptly and facilely.
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Hobman JL, Julian DJ, Brown NL. Cysteine coordination of Pb(II) is involved in the PbrR-dependent activation of the lead-resistance promoter, PpbrA, from Cupriavidus metallidurans CH34. BMC Microbiol 2012; 12:109. [PMID: 22708803 PMCID: PMC3431237 DOI: 10.1186/1471-2180-12-109] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Accepted: 06/07/2012] [Indexed: 11/30/2022] Open
Abstract
Background The pbr resistance operon from Cupriavidus metallidurans CH34 plasmid pMOL30 confers resistance to Pb(II) salts, and is regulated by the Pb(II) responsive regulator PbrR, which is a MerR family activator. In other metal sensing MerR family regulators, such as MerR, CueR, and ZntR the cognate regulator binds to a promoter with an unusually long spacer between the −35 and −10 sequences, and activates transcription of resistance genes as a consequence of binding the appropriate metal. Cysteine residues in these regulators are essential for metal ion coordination and activation of expression from their cognate promoter. In this study we investigated the interaction of PbrR with the promoter for the structural pbr resistance genes, PpbrA, effects on transcriptional activation of altering the DNA sequence of PpbrA, and effects on Pb(II)-induced activation of PpbrA when cysteine residues in PbrR were mutated to serine. Results Gel retardation and footprinting assays using purified PbrR show that it binds to, and protects from DNase I digestion, the PpbrA promoter, which has a 19 bp spacer between its −35 and −10 sites. Using β-galactosidase assays in C. metallidurans, we show that when PpbrA is changed to an 18 bp spacer, there is an increase in transcriptional activation both in the presence and absence of Pb(II) salts up to a maximum induction equivalent to that seen in the fully-induced wild-type promoter. Changes to the −10 sequence of PpbrA from TTAAAT to the consensus E. coli −10 sequence (TATAAT) increased transcriptional activation from PpbrA, whilst changing the −10 sequence to that of the Tn501 mer promoter (TAAGGT) also increased the transcriptional response, but only in the presence of Pb(II). Individual PbrR mutants C14S, C55S, C79S, C114S, C123S, C132S and C134S, and a double mutant C132S/C134S, were tested for Pb(II) response from PpbrA, using β-galactosidase assays in C. metallidurans. The PbrR C14S, C79S, C134S, and C132S/C134S mutants were defective in Pb(II)-induced activation of PpbrA. Conclusions These data show that the metal-dependent activation of PbrR occurs by a similar mechanism to that of MerR, but that metal ion coordination is through cysteines which differ from those seen in other MerR family regulators, and that the DNA sequence of the −10 promoter affects expression levels of the lead resistance genes.
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Affiliation(s)
- Jon L Hobman
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK.
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Decker KB, James TD, Stibitz S, Hinton DM. The Bordetella pertussis model of exquisite gene control by the global transcription factor BvgA. MICROBIOLOGY-SGM 2012; 158:1665-1676. [PMID: 22628479 DOI: 10.1099/mic.0.058941-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bordetella pertussis causes whooping cough, an infectious disease that is reemerging despite widespread vaccination. A more complete understanding of B. pertussis pathogenic mechanisms will involve unravelling the regulation of its impressive arsenal of virulence factors. Here we review the action of the B. pertussis response regulator BvgA in the context of what is known about bacterial RNA polymerase and various modes of transcription activation. At most virulence gene promoters, multiple dimers of phosphorylated BvgA (BvgA~P) bind upstream of the core promoter sequence, using a combination of high- and low-affinity sites that fill through cooperativity. Activation by BvgA~P is typically mediated by a novel form of class I/II mechanisms, but two virulence genes, fim2 and fim3, which encode serologically distinct fimbrial subunits, are regulated using a previously unrecognized RNA polymerase/activator architecture. In addition, the fim genes undergo phase variation because of an extended cytosine (C) tract within the promoter sequences that is subject to slipped-strand mispairing during replication. These sophisticated systems of regulation demonstrate one aspect whereby B. pertussis, which is highly clonal and lacks the extensive genetic diversity observed in many other bacterial pathogens, has been highly successful as an obligate human pathogen.
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Affiliation(s)
- Kimberly B Decker
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tamara D James
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Scott Stibitz
- Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA
| | - Deborah M Hinton
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Guerra AJ, Giedroc DP. Metal site occupancy and allosteric switching in bacterial metal sensor proteins. Arch Biochem Biophys 2012; 519:210-22. [PMID: 22178748 PMCID: PMC3312040 DOI: 10.1016/j.abb.2011.11.021] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/23/2011] [Accepted: 11/29/2011] [Indexed: 12/22/2022]
Abstract
All prokaryotes encode a panel of metal sensor or metalloregulatory proteins that govern the expression of genes that allows an organism to quickly adapt to toxicity or deprivation of both biologically essential transition metal ions, e.g., Zn, Cu, Fe, and heavy metal pollutants. As such, metal sensor proteins can be considered arbiters of intracellular transition metal bioavailability and thus potentially control the metallation state of the metalloproteins in the cell. Metal sensor proteins are specialized allosteric proteins that regulate transcription as a result direct binding of one or two cognate metal ions, to the exclusion of all others. In most cases, the binding of the cognate metal ion induces a structural change in a protein oligomer that either activates or inhibits operator DNA binding. A quantitative measure of the degree to which a particular metal drives metalloregulation of operator DNA-binding is the allosteric coupling free energy, ΔGc. In this review, we summarize recent work directed toward understanding metal occupancy and metal selectivity of these allosteric switches in selected families of metal sensor proteins and examine the structural origins of ΔGc in the functional context a thermodynamic "set-point" model of intracellular metal homeostasis.
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Affiliation(s)
- Alfredo J. Guerra
- Department of Chemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN USA 47405-7102
| | - David P. Giedroc
- Department of Chemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN USA 47405-7102
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42
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Berkmen M. Production of disulfide-bonded proteins in Escherichia coli. Protein Expr Purif 2012; 82:240-51. [DOI: 10.1016/j.pep.2011.10.009] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 10/24/2011] [Accepted: 10/27/2011] [Indexed: 10/15/2022]
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Abstract
The intracellular availability of all biologically required transition metal ions in bacteria, e.g., Zn, Cu, Fe, as well as the detoxification of nonbiological heavy metal pollutants, is controlled at the molecular level by a panel of metalloregulatory or "metal sensor" proteins. Metal sensor proteins are specialized allosteric proteins that regulate the transcription of genes linked to transition metal homeostasis as a result of direct binding of a single metal ion or two closely related metal ions, to the exclusion of all others. In many cases, the binding of the cognate metal ion induces a structural change in a metal sensor oligomer that either activates or inhibits operator DNA binding. A quantitative measure of the degree to which a particular metal drives metalloregulation of transcription is the allosteric coupling-free energy, ΔG(c). In this chapter, we outline detailed spectroscopically derived methods for measuring metal binding affinity, K(Me), as well as ΔG(c) independent of K(Me), presented in the context of a simple coupled equilibrium scheme. Studies carried out in this way provide quantitative insights into the degree to which a particular metal ion is capable of driving allosteric switching, and via ligand substitution, the extent to which individual coordination bonds establish structural linkage of allosteric metal and operator DNA-binding sites.
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Lag phase is a distinct growth phase that prepares bacteria for exponential growth and involves transient metal accumulation. J Bacteriol 2011; 194:686-701. [PMID: 22139505 DOI: 10.1128/jb.06112-11] [Citation(s) in RCA: 327] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lag phase represents the earliest and most poorly understood stage of the bacterial growth cycle. We developed a reproducible experimental system and conducted functional genomic and physiological analyses of a 2-h lag phase in Salmonella enterica serovar Typhimurium. Adaptation began within 4 min of inoculation into fresh LB medium with the transient expression of genes involved in phosphate uptake. The main lag-phase transcriptional program initiated at 20 min with the upregulation of 945 genes encoding processes such as transcription, translation, iron-sulfur protein assembly, nucleotide metabolism, LPS biosynthesis, and aerobic respiration. ChIP-chip revealed that RNA polymerase was not "poised" upstream of the bacterial genes that are rapidly induced at the beginning of lag phase, suggesting a mechanism that involves de novo partitioning of RNA polymerase to transcribe 522 bacterial genes within 4 min of leaving stationary phase. We used inductively coupled plasma mass spectrometry (ICP-MS) to discover that iron, calcium, and manganese are accumulated by S. Typhimurium during lag phase, while levels of cobalt, nickel, and sodium showed distinct growth-phase-specific patterns. The high concentration of iron during lag phase was associated with transient sensitivity to oxidative stress. The study of lag phase promises to identify the physiological and regulatory processes responsible for adaptation to new environments.
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45
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McEwan AG, Djoko KY, Chen NH, Couñago RLM, Kidd SP, Potter AJ, Jennings MP. Novel bacterial MerR-like regulators their role in the response to carbonyl and nitrosative stress. Adv Microb Physiol 2011; 58:1-22. [PMID: 21722790 DOI: 10.1016/b978-0-12-381043-4.00001-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recognition of the diversity of transcriptional regulators of the MerR family has increased considerably over the last decade and it has been established that not all MerR-like regulators are involved in metal ion recognition. A new type of MerR-like regulator was identified in Neisseria gonorrhoeae that is distinct from metal-binding MerR proteins. This novel transcription factor, the Neisseria merR-like regulator (NmlR) is related to a large and diverse group of MerR-like regulators. A common feature of the majority of the genes encoding the nmlR-related genes is that they predicted to control the expression of adhC, which encodes a glutathione-dependent alcohol dehydrogenase. The function of the NmlR regulon appears to be to defend the bacterial cell against carbonyl stress and in some cases nitrosative stress. A potential role for NmlR in bacterial pathogenesis has been identified in Neisseria gonorrhoeae and Streptococcus pneumoniae. Although it is not known how NmlR is activated it is suggested that conserved cysteine residues may be involved in thiol-based signaling.
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Affiliation(s)
- Alastair G McEwan
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Australia
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Hödar C, Moreno P, di Genova A, Latorre M, Reyes-Jara A, Maass A, González M, Cambiazo V. Genome wide identification of Acidithiobacillus ferrooxidans (ATCC 23270) transcription factors and comparative analysis of ArsR and MerR metal regulators. Biometals 2011; 25:75-93. [PMID: 21830017 DOI: 10.1007/s10534-011-9484-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 07/21/2011] [Indexed: 10/25/2022]
Abstract
Acidithiobacillus ferrooxidans is a chemolithoautotrophic acidophilic bacterium that obtains its energy from the oxidation of ferrous iron, elemental sulfur, or reduced sulfur minerals. This capability makes it of great industrial importance due to its applications in biomining. During the industrial processes, A. ferrooxidans survives to stressing circumstances in its environment, such as an extremely acidic pH and high concentration of transition metals. In order to gain insight into the organization of A. ferrooxidans regulatory networks and to provide a framework for further studies in bacterial growth under extreme conditions, we applied a genome-wide annotation procedure to identify 87 A. ferrooxidans transcription factors. We classified them into 19 families that were conserved among diverse prokaryotic phyla. Our annotation procedure revealed that A. ferrooxidans genome contains several members of the ArsR and MerR families, which are involved in metal resistance and detoxification. Analysis of their sequences revealed known and potentially new mechanism to coordinate gene-expression in response to metal availability. A. ferrooxidans inhabit some of the most metal-rich environments known, thus transcription factors identified here seem to be good candidates for functional studies in order to determine their physiological roles and to place them into A. ferrooxidans transcriptional regulatory networks.
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Affiliation(s)
- Christian Hödar
- Laboratorio de Bioinformática y Expresión Génica, INTA, Universidad de Chile, El Libano 5524, Santiago, Chile
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Cd-specific mutants of mercury-sensing regulatory protein MerR, generated by directed evolution. Appl Environ Microbiol 2011; 77:6215-24. [PMID: 21764963 DOI: 10.1128/aem.00662-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mercury-sensing regulatory protein, MerR (Tn21), which regulates mercury resistance operons in Gram-negative bacteria, was subjected to directed evolution in an effort to generate a MerR mutant that responds to Cd but not Hg. Oligonucleotide-directed mutagenesis was used to introduce random mutations into the key metal-binding regions of MerR. The effects of these mutations were assessed using a vector in which MerR controlled the expression of green fluorescent protein (GFP) and luciferase via the mer operator/promoter. An Escherichia coli cell library was screened by fluorescence-activated cell sorting, using a fluorescence-based dual screening strategy that selected for MerR mutants that showed GFP repression when cells were induced with Hg but GFP activation in the presence of Cd. Two Cd-responsive MerR mutants with decreased responses toward Hg were identified through the first mutagenesis/selection round. These mutants were used for a second mutagenesis/selection round, which yielded eight Cd-specific mutants that had no significant response to Hg, Zn, or the other tested metal(loid)s. Seven of the eight Cd-specific MerR mutants showed repressor activities equal to that of wild-type (wt) MerR. These Cd-specific mutants harbored multiple mutations (12 to 22) in MerR, indicating that the alteration of metal specificity with maintenance of repressor function was due to the combined effect of many mutations rather than just a few amino acid changes. The amino acid changes were studied by alignment against the sequences of MerR and other metal-responsive MerR family proteins. The analysis indicated that the generated Cd-specific MerR mutants appear to be unique among the MerR family members characterized to date.
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Abstract
Gold ions are mobilized and disseminated through the environment and enter into the cells by non-specific intake. To avoid deleterious effect that occurs even at very low concentrations, bacteria such as Salmonella enterica and Cupriavidus metallidurans use Au-specific MerR-type transcriptional regulators to detect the presence of these toxic ions, and control the expression of specific resistance factors. In contrast to the related copper sensor CueR, the Au-selective metalloregulatory proteins are able to distinguish Au(I) from Cu(I) or Ag(I). This is achieved by finely tuning a single dithiolate metal coordination with conserved cysteine residues at the metal binding site of the proteins to lower the affinity for Cu(I) in comparison to the Cu-sensors, while maintaining or even increasing the affinity for Au(I). In Salmonella, GolS not only privileges the binding of Au(I) over Cu(I) or Ag(I), but also distinguishes its target recognition sites in its regulated promoters minimizing cross-activation of CueR-controlled operators. In this sense, the presence of a selective Au sensory devise would allow species harbouring resident Cu-homeostasis systems to eliminate the toxic ion without affecting Cu acquisition in Au rich environments.
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49
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Rao L, Cui Q, Xu X. Electronic Properties and Desolvation Penalties of Metal Ions Plus Protein Electrostatics Dictate the Metal Binding Affinity and Selectivity in the Copper Efflux Regulator. J Am Chem Soc 2010; 132:18092-102. [DOI: 10.1021/ja103742k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Li Rao
- Department of Chemistry, Xiamen University, Xiamen, P. R. China, and Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Qiang Cui
- Department of Chemistry, Xiamen University, Xiamen, P. R. China, and Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Xin Xu
- Department of Chemistry, Xiamen University, Xiamen, P. R. China, and Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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50
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Pérez Audero ME, Podoroska BM, Ibáñez MM, Cauerhff A, Checa SK, Soncini FC. Target transcription binding sites differentiate two groups of MerR-monovalent metal ion sensors. Mol Microbiol 2010; 78:853-65. [PMID: 20807206 DOI: 10.1111/j.1365-2958.2010.07370.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The evolution of bacterial regulatory circuits often involves duplication of genes encoding transcription factors that may suffer both modifications in their detected signals, as well as, rewiring of their target operators. This, and subsequent horizontal gene transfer events contribute to generate a diverse array of regulatory pathways. In Salmonella, two homologous transcription factors CueR and GolS are responsible for Cu and Au sensing and resistance respectively. They share similarities not only in their sequence but also in their target binding sites, although they cluster separately among MerR-monovalent metal sensors. Here, we demonstrate that CueR and GolS can selectively distinguish their target binding sites by recognizing bases at positions 3' and 3 of their cognate operators. Swap of these bases results in switching regulator dependency. The differences in promoter architecture plus the environmentally controlled regulator's cytoplasmic availability warrant intra-regulon regulator-operator selectivity, and the proper response to metal injury. Furthermore, the presence of the distinctive operators' bases is widely extended among the two groups of MerR-monovalent metal sensors, providing evidence of the co-evolution of these factors and their target operators. This approach allows the prediction of regulator's dependency and the identification of transcription modules among groups of homologous transcription factors.
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Affiliation(s)
- María E Pérez Audero
- Instituto de Biología Molecular, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Suipacha 531, S2002LRK-Rosario, Argentina
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