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Méndez AAE, Argüello JM, Soncini FC, Checa SK. Scs system links copper and redox homeostasis in bacterial pathogens. J Biol Chem 2024; 300:105710. [PMID: 38309504 PMCID: PMC10907172 DOI: 10.1016/j.jbc.2024.105710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/09/2024] [Accepted: 01/16/2024] [Indexed: 02/05/2024] Open
Abstract
The bacterial envelope is an essential compartment involved in metabolism and metabolites transport, virulence, and stress defense. Its roles become more evident when homeostasis is challenged during host-pathogen interactions. In particular, the presence of free radical groups and excess copper in the periplasm causes noxious reactions, such as sulfhydryl group oxidation leading to enzymatic inactivation and protein denaturation. In response to this, canonical and accessory oxidoreductase systems are induced, performing quality control of thiol groups, and therefore contributing to restoring homeostasis and preserving survival under these conditions. Here, we examine recent advances in the characterization of the Dsb-like, Salmonella-specific Scs system. This system includes the ScsC/ScsB pair of Cu+-binding proteins with thiol-oxidoreductase activity, an alternative ScsB-partner, the membrane-linked ScsD, and a likely associated protein, ScsA, with a role in peroxide resistance. We discuss the acquisition of the scsABCD locus and its integration into a global regulatory pathway directing envelope response to Cu stress during the evolution of pathogens that also harbor the canonical Dsb systems. The evidence suggests that the canonical Dsb systems cannot satisfy the extra demands that the host-pathogen interface imposes to preserve functional thiol groups. This resulted in the acquisition of the Scs system by Salmonella. We propose that the ScsABCD complex evolved to connect Cu and redox stress responses in this pathogen as well as in other bacterial pathogens.
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Affiliation(s)
- Andrea A E Méndez
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - José M Argüello
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina.
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2
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Tulin G, Figueroa NR, Checa SK, Soncini FC. The multifarious MerR family of transcriptional regulators. Mol Microbiol 2024; 121:230-242. [PMID: 38105009 DOI: 10.1111/mmi.15212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/28/2023] [Accepted: 12/05/2023] [Indexed: 12/19/2023]
Abstract
The MerR family of transcriptional regulators includes a variety of bacterial cytoplasmic proteins that respond to a wide range of signals, including toxins, metal ions, and endogenous metabolites. Its best-characterized members share similar structural and functional features with the family founder, the mercury sensor MerR, although most of them do not respond to metal ions. The group of "canonical" MerR homologs displays common molecular mechanisms for controlling the transcriptional activation of their target genes in response to inducer signals. This includes the recognition of distinctive operator sequences located at suboptimal σ70 -dependent promoters. Interestingly, an increasing number of proteins assigned to the MerR family based on their DNA-binding domain do not match in structure, sequence, or mode of action with any of the canonical MerR-like regulators. Here, we analyzed several members of the family, including this last group. Based on a phylogenetic analysis, and similarities in structural/functional features and position of their target operators relative to the promoter elements, we propose to assign these "atypical/divergent" MerR regulators to a phylogenetically separated group. These atypical/divergent homologs represent a new class of transcriptional regulators with novel regulatory mechanisms.
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Affiliation(s)
- Gonzalo Tulin
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Nicolás R Figueroa
- Centro de Estudios Fotosintéticos y Bioquímicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
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3
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Mendoza JI, Lescano J, Soncini FC, Checa SK. The protein scaffold calibrates metal specificity and activation in MerR sensors. Microb Biotechnol 2022; 15:2992-3002. [PMID: 36134649 PMCID: PMC9733647 DOI: 10.1111/1751-7915.14151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/09/2022] [Accepted: 09/12/2022] [Indexed: 12/14/2022] Open
Abstract
MerR metalloregulators are the central components of many biosensor platforms designed to report metal contamination. However, most MerR proteins are non-specific. This makes it difficult to apply these biosensors in the analysis of real environmental samples. On-demand implementation of molecular engineering to modify the MerR metal preferences is innovative, although it does not always yield the expected results. As the metal binding loop region (MBL) of these sensors has been proposed to be the major modulator of their specificity, we surgically switched this region for that of well-characterized specific and non-specific homologues. We found that identical modifications in different MerR proteins result in synthetic sensors displaying particular metal-detection patterns that cannot be predicted from the nature of the assembled modules. For instance, the MBL from a native Hg(II) sensor provided non-specificity or specificity toward Hg(II) or Cd(II) depending on the MerR scaffold into which it was integrated. These and other evidences reveal that residues outside the MBL are required to modulate ion recognition and transduce the input signal to the target promoter. Revealing their identity and their interactions with other residues is a critical step toward the design of more efficient biosensor devices for environmental metal monitoring.
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Affiliation(s)
- Julián I. Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR)Universidad Nacional de Rosario (UNR)‐Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)RosarioArgentina
| | - Julián Lescano
- Instituto de Biología Molecular y Celular de Rosario (IBR)Universidad Nacional de Rosario (UNR)‐Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)RosarioArgentina
| | - Fernando C. Soncini
- Instituto de Biología Molecular y Celular de Rosario (IBR)Universidad Nacional de Rosario (UNR)‐Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)RosarioArgentina,Departamento de Microbiología, Facultad de Ciencias Bioquímicas y FarmacéuticasUniversidad Nacional de RosarioRosarioArgentina
| | - Susana K. Checa
- Instituto de Biología Molecular y Celular de Rosario (IBR)Universidad Nacional de Rosario (UNR)‐Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)RosarioArgentina,Departamento de Microbiología, Facultad de Ciencias Bioquímicas y FarmacéuticasUniversidad Nacional de RosarioRosarioArgentina
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4
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Méndez AAE, Mendoza JI, Echarren ML, Terán I, Checa SK, Soncini FC. Evolution of Copper Homeostasis and Virulence in Salmonella. Front Microbiol 2022; 13:823176. [PMID: 35369444 PMCID: PMC8966772 DOI: 10.3389/fmicb.2022.823176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/14/2022] [Indexed: 11/24/2022] Open
Abstract
Salmonella enterica sv. Typhimurium modulates the expression of factors essential for virulence, contributing to its survival against the surge of copper (Cu) in the Salmonella-containing vacuole. This bactericidal host innate immune component primarily targets the bacterial envelope, where most cuproproteins are localized. While in most enteric species periplasmic Cu homeostasis is maintained by the CusR/CusS-controlled CusCFBA efflux system encoded in the cus locus, we noticed that these genes were lost from the Salmonella-core genome. At the same time, Salmonella acquired cueP, coding for a periplasmic Cu chaperone. As cus, cueP was shown to be essential for bacterial survival in a copper-rich environment under anaerobiosis, suggesting that it can functionally substitute the CusCFBA system. In the present study, the whole Escherichia coli cus locus was reintroduced to the chromosome of the Salmonella wild-type or the ΔcueP strain. While the integrated cus locus did not affect Cu resistance under aerobic conditions, it increases Cu tolerance under anaerobiosis, irrespective of the presence or absence of cueP. In contrast to the Cus system, CueP expression is higher at high copper concentrations and persisted over time, suggesting separate functions. Finally, we observed that, regardless of the presence or absence of cus, a mutant deleted of cueP shows a deficiency in replication inside macrophages compared to the wild-type strain. Our results demonstrate that CueP and CusCFBA exert redundant functions for metal resistance, but not for intracellular survival, and therefore for the virulence of this pathogen.
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Affiliation(s)
- Andrea A E Méndez
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Julián I Mendoza
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - María Laura Echarren
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Ignacio Terán
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
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5
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Echarren ML, Figueroa NR, Vitor-Horen L, Pucciarelli MG, García-Del Portillo F, Soncini FC. Balance between bacterial extracellular matrix production and intramacrophage proliferation by a Salmonella-specific SPI-2 encoded transcription factor. Mol Microbiol 2021; 116:1022-1032. [PMID: 34342063 DOI: 10.1111/mmi.14789] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 11/27/2022]
Abstract
Biosynthesis and secretion of a complex extracellular matrix (EM) is a hallmark of Salmonella biofilm formation, impacting on its relationship with both the environment and the host. Cellulose is a major component of Salmonella EM. It is considered an anti-virulence factor because it interferes with Salmonella proliferation inside macrophages and virulence in mice. Its synthesis is stimulated by CsgD, the master regulator of biofilm formation in enterobacteria, which in turn is under the control of MlrA, a MerR-like transcription factor. In this work we identified a SPI-2 encoded Salmonella-specific transcription factor homolog to MlrA, MlrB, that represses transcription of its downstream gene, orf319, and of csgD inside host cells. MlrB is induced in laboratory media mimicking intracellular conditions and inside macrophages, and it is required for intramacrophage proliferation. An increased csgD expression is observed in the absence of MlrB inside host cells. Interestingly, inactivation of the CsgD-controlled cellulose synthase-coding gene restored intramacrophage proliferation to rates comparable to wild type bacteria in the absence of MlrB. These data indicate that MlrB represses CsgD expression inside host cells and suggest that this repression lowers the activation of the cellulose synthase. Our findings provide a novel link between biofilm formation and Salmonella virulence.
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Affiliation(s)
- María Laura Echarren
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Nicolás R Figueroa
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Luisina Vitor-Horen
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - M Graciela Pucciarelli
- Departmento de Biología Molecular, Universidad Autónoma de Madrid, Centro de Biología Molecular 'Severo Ochoa' (CBMSO)-CSIC, 28049, Madrid, Spain.,Laboratorio de Patógenos Bacterianos Intracelulares. Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Francisco García-Del Portillo
- Laboratorio de Patógenos Bacterianos Intracelulares. Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
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6
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Mendoza JI, Soncini FC, Checa SK. Engineering of a Au-sensor to develop a Hg-specific, sensitive and robust whole-cell biosensor for on-site water monitoring. Chem Commun (Camb) 2020; 56:6590-6593. [PMID: 32406434 DOI: 10.1039/d0cc01323d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A highly sensitive and specific Hg-whole-cell biosensor was developed from a non-selective variant of the Au sensor GolS and its regulatory pathway. The performance of this analytical tool was validated under laboratory and field-like conditions. This biosensor can be easily applied in cost-effective and portable semiquantitative devices to report Hg contamination in water.
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Affiliation(s)
- Julián I Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario, Argentina.
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7
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Cerminati S, Giri GF, Mendoza JI, Soncini FC, Checa SK. The CpxR/CpxA system contributes to Salmonella gold-resistance by controlling the GolS-dependent gesABC transcription. Environ Microbiol 2017. [PMID: 28631419 DOI: 10.1111/1462-2920.13837] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several regulatory systems contribute to bacterial resistance to heavy metals controlling the expression of factors required to eliminate the intoxicant and/or to repair the damage caused by it. In Salmonella, the response to Au ions is mediated by the specific metalloregulator GolS that, among other genes, controls the expression of the RND-efflux pump GesABC. In this work, we demonstrate that CpxR/CpxA, a main cell-envelope stress-responding system, promotes gesABC transcription in the presence of Au ions at neutral pH. Deletion of either cpxA or cpxR, or mutation of the CpxR-binding site identified upstream of the GolS-operator in the gesABC promoter region reduces but does not abrogate the GolS- and Au-dependent activation of gesABC. Au also triggers the activation of the CpxR/CpxA system and deletion of the cpxRA operon severely reduces survival in the presence of the toxic metal. Our results indicate that the coordinated action of GolS and CpxR/CpxA contribute to protecting the cell from severe Au damage.
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Affiliation(s)
- Sebastián Cerminati
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Germán F Giri
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Julián I Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
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8
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Rico-Pérez G, Pezza A, Pucciarelli MG, de Pedro MA, Soncini FC, García-del Portillo F. A novel peptidoglycan D,L-endopeptidase induced by Salmonella inside eukaryotic cells contributes to virulence. Mol Microbiol 2015; 99:546-56. [PMID: 26462856 DOI: 10.1111/mmi.13248] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2015] [Indexed: 12/25/2022]
Abstract
Bacteria remodel peptidoglycan structure in response to environmental changes. Many enzymes are involved in peptidoglycan metabolism; however, little is known about their responsiveness in a defined environment or the modes they assist bacteria to adapt to new niches. Here, we focused in peptidoglycan enzymes that intracellular bacterial pathogens use inside eukaryotic cells. We identified a peptidoglycan enzyme induced by Salmonella enterica serovar Typhimurium in fibroblasts and epithelial cells. This enzyme, which shows γ-D-glutamyl-meso-diaminopimelic acid D,L-endopeptidase activity, is also produced by the pathogen in media with limited nutrients and in resting conditions. The enzyme, termed EcgA for endopeptidase responding to cessation of growth', is encoded in a S. Typhimurium genomic island absent in Escherichia coli. EcgA production is strictly dependent on the virulence regulator PhoP in extra- and intracellular environments. Consistent to this regulation, a mutant lacking EcgA is attenuated in the mouse typhoid model. These findings suggest that specialised peptidoglycan enzymes, such as EcgA, might facilitate Salmonella adaptation to the intracellular lifestyle. Moreover, they indicate that readjustment of peptidoglycan metabolism inside the eukaryotic cell is essential for host colonisation.
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Affiliation(s)
- Gadea Rico-Pérez
- Laboratory of Intracellular Bacterial Pathogens, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Alejandro Pezza
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - M Graciela Pucciarelli
- Laboratory of Intracellular Bacterial Pathogens, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain.,Centro de Biología Molecular 'Severo Ochoa' (CBMSO-CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel A de Pedro
- Centro de Biología Molecular 'Severo Ochoa' (CBMSO-CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina
| | - Francisco García-del Portillo
- Laboratory of Intracellular Bacterial Pathogens, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
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9
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Hao X, Lüthje FL, Qin Y, McDevitt SF, Lutay N, Hobman JL, Asiani K, Soncini FC, German N, Zhang S, Zhu YG, Rensing C. Survival in amoeba--a major selection pressure on the presence of bacterial copper and zinc resistance determinants? Identification of a "copper pathogenicity island". Appl Microbiol Biotechnol 2015; 99:5817-24. [PMID: 26088177 DOI: 10.1007/s00253-015-6749-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/22/2015] [Accepted: 05/27/2015] [Indexed: 11/24/2022]
Abstract
The presence of metal resistance determinants in bacteria usually is attributed to geological or anthropogenic metal contamination in different environments or associated with the use of antimicrobial metals in human healthcare or in agriculture. While this is certainly true, we hypothesize that protozoan predation and macrophage killing are also responsible for selection of copper/zinc resistance genes in bacteria. In this review, we outline evidence supporting this hypothesis, as well as highlight the correlation between metal resistance and pathogenicity in bacteria. In addition, we introduce and characterize the "copper pathogenicity island" identified in Escherichia coli and Salmonella strains isolated from copper- and zinc-fed Danish pigs.
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Affiliation(s)
- Xiuli Hao
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, People's Republic of China
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10
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Cerminati S, Soncini FC, Checa SK. A sensitive whole-cell biosensor for the simultaneous detection of a broad-spectrum of toxic heavy metal ions. Chem Commun (Camb) 2015; 51:5917-20. [PMID: 25730473 DOI: 10.1039/c5cc00981b] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bacterial biosensors are simple, cost-effective and efficient analytical tools for detecting bioavailable heavy metals in the environment. This work presents the design, construction and calibration of a novel whole-cell fluorescent biosensory device that, simultaneously and with high sensitivity, reports the presence of toxic mercury, lead, cadmium and/or gold ions in aqueous samples. This bio-reporter can be easily applied as an immediate alerting tool for detecting the presence of harmful pollutants in drinking water.
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Affiliation(s)
- S Cerminati
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas (UNR), Ocampo y Esmeralda, 2000-Rosario, Argentina.
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11
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Abriata LA, Pontel LB, Vila AJ, Dal Peraro M, Soncini FC. A dimerization interface mediated by functionally critical residues creates interfacial disulfide bonds and copper sites in CueP. J Inorg Biochem 2014; 140:199-201. [PMID: 25151035 DOI: 10.1016/j.jinorgbio.2014.07.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Revised: 07/28/2014] [Accepted: 07/30/2014] [Indexed: 11/27/2022]
Abstract
CueP confers bacterial copper resistance in the periplasm, particularly under anaerobic conditions, through an unknown mechanism. The only available structure and limited solution data suggest that CueP forms noncovalent dimers in solution, whereas sequence conservation suggests important roles for three cysteines and two histidines as copper ligands. Here we report evidence of a dimerization equilibrium mediated by a newly identified interface of functional relevance, which occludes internal copper sites and disulfide bonds but allows for intra- and interchain disulfide bonding, an extensive disulfide relay, and interfacial copper sites. Our results suggest a role for CueP linking redox-state sensing and copper detoxification.
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Affiliation(s)
- Luciano A Abriata
- Laboratory of Biomolecular Modeling, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland.
| | - Lucas B Pontel
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET, UNR), 2000 Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET, UNR), 2000 Rosario, Argentina
| | - Matteo Dal Peraro
- Laboratory of Biomolecular Modeling, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET, UNR), 2000 Rosario, Argentina.
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12
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Pontel LB, Scampoli NL, Porwollik S, Checa SK, McClelland M, Soncini FC. Identification of a Salmonella ancillary copper detoxification mechanism by a comparative analysis of the genome-wide transcriptional response to copper and zinc excess. Microbiology (Reading) 2014; 160:1659-1669. [PMID: 24858080 DOI: 10.1099/mic.0.080473-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Copper and zinc are essential metal ions, but toxic in excess. Bacteria have evolved different strategies to control their intracellular concentrations, ensuring proper supply while avoiding toxicity, including the induction of metal-specific as well as non-specific mechanisms. We compared the transcriptional profiles of Salmonella Typhimurium after exposure to either copper or zinc ions in both rich and minimal media. Besides metal-specific regulatory networks many global stress-response pathways react to an excess of either of these metal ions. Copper excess affects both zinc and iron homeostasis by inducing transcription of these metal-specific regulons. In addition to the control of zinc-specific regulons, zinc excess affects the Cpx regulon and the σ(E) envelope-stress responses. Finally, novel metal-specific upregulated genes were detected including a new copper-detoxification pathway that involves the siderophore enterobactin and the outer-membrane protein TolC. This work sheds light onto the transcriptional landscape of Salmonella after copper or zinc overload, and discloses a new mechanism of copper detoxification.
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Affiliation(s)
- Lucas B Pontel
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Ocampo y Esmeralda, 2000-Rosario, Argentina
| | - Nadia L Scampoli
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Ocampo y Esmeralda, 2000-Rosario, Argentina
| | - Steffen Porwollik
- Department of Pathology and Laboratory Medicine, University of California, Irvine, CA, USA
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA, USA
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Ocampo y Esmeralda, 2000-Rosario, Argentina
| | - Michael McClelland
- Department of Pathology and Laboratory Medicine, University of California, Irvine, CA, USA
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA, USA
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Ocampo y Esmeralda, 2000-Rosario, Argentina
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13
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Humbert MV, Rasia RM, Checa SK, Soncini FC. Protein signatures that promote operator selectivity among paralog MerR monovalent metal ion regulators. J Biol Chem 2013; 288:20510-9. [PMID: 23733186 DOI: 10.1074/jbc.m113.452797] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Two paralog transcriptional regulators of the MerR family, CueR and GolS, are responsible for monovalent metal ion sensing and resistance in Salmonella enterica. Although similar in sequence and also in their target binding sites, these proteins differ in signal detection and in the set of target genes they control. Recently, we demonstrated that selective promoter recognition depends on the presence of specific bases located at positions 3' and 3 within the operators they interact with. Here, we identify the amino acid residues within the N-terminal DNA-binding domain of these sensor proteins that are directly involved in operator discrimination. We demonstrate that a methionine residue at position 16 of GolS, absolutely conserved among GolS-like proteins but absent in all CueR-like xenologs, is the key to selectively recognize operators that harbor the distinctive GolS-operator signature, whereas the residue at position 19 finely tunes the regulator/operator interaction. Furthermore, swapping these residues switches the set of genes recognized by these transcription factors. These results indicate that co-evolution of a regulator and its cognate operators within the bacterial cell provides the conditions to avoid cross-recognition and guarantees the proper response to metal injury.
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Affiliation(s)
- María V Humbert
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Universidad Nacional de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Ocampo y Esmeralda, 2000-Rosario, Argentina
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14
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Checa SK, Zurbriggen MD, Soncini FC. Bacterial signaling systems as platforms for rational design of new generations of biosensors. Curr Opin Biotechnol 2012; 23:766-72. [DOI: 10.1016/j.copbio.2012.05.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 01/30/2023]
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15
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Cerminati S, Soncini FC, Checa SK. Selective detection of gold using genetically engineered bacterial reporters. Biotechnol Bioeng 2011; 108:2553-60. [DOI: 10.1002/bit.23213] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 04/20/2011] [Accepted: 05/13/2011] [Indexed: 11/07/2022]
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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17
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Barchiesi J, Espariz M, Checa SK, Soncini FC. Downregulation of RpoN-controlled genes protects Salmonella cells from killing by the cationic antimicrobial peptide polymyxin B. FEMS Microbiol Lett 2008; 291:73-9. [PMID: 19076233 DOI: 10.1111/j.1574-6968.2008.01437.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Salmonella enterica polymyxin B (PM) resistance is modulated mainly by substitutions of the acyl chains and the phosphate groups on the lipid A moiety of lipopolysaccharide. These modifications are mediated by genes under the control of the PmrA/PmrB and PhoP/PhoQ two-component regulatory systems. In this study, a deletion in the gene encoding the alternative sigma(54) factor, rpoN, was shown to increase PM resistance without affecting protamine sensitivity. The results presented here showed that the increased polymyxin resistance observed in the DeltarpoN mutant occurs through a PmrA/PhoP-independent pathway. Downregulation of one or more genes belonging to the RpoN regulon may provide an additional mechanism of defence against membrane-permeabilizing antimicrobial peptides that helps the pathogen to survive in different environments.
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Affiliation(s)
- Julieta Barchiesi
- Departamento de Microbiología, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Spinelli SV, Pontel LB, García Véscovi E, Soncini FC. Regulation of magnesium homeostasis in Salmonella: Mg(2+) targets the mgtA transcript for degradation by RNase E. FEMS Microbiol Lett 2008; 280:226-34. [PMID: 18248433 DOI: 10.1111/j.1574-6968.2008.01065.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Extracellular Mg(2+) controls the activation of the Salmonella PhoP/PhoQ regulatory system. One of the adaptive responses driven by PhoP/PhoQ includes the transcriptional induction of mgtA and mgtCB, which encode two P-type Mg(2+) transporters. Mg(2+) also controls mgtA expression by a riboswitch located in its 5'-untranslated region (5'UTR). In this work, it was shown that the 5'UTR of both mgtA and mgtCB is responsible for a fine-tuned Mg(2+)-dependent regulation of these genes. Evidence was also provided that the Mg(2+) riboswitch targets the mgtA transcript for degradation by RNase E when cells are grown in high Mg(2+) environments.
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Affiliation(s)
- Silvana V Spinelli
- Departamento de Microbiología, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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20
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Pontel LB, Audero MEP, Espariz M, Checa SK, Soncini FC. GolS controls the response to gold by the hierarchical induction of Salmonella-specific genes that include a CBA efflux-coding operon. Mol Microbiol 2007; 66:814-25. [PMID: 17919284 DOI: 10.1111/j.1365-2958.2007.05963.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Salmonella employs a specific set of proteins that allows it to detect the presence of gold salts in the environment and to mount the appropriate resistance response. This includes a P-type ATPase, GolT, and a small cytoplasmic metal binding protein, GolB. Their expression is controlled by a MerR-like sensor, GolS, which is highly selective for Au ions. Here, we identify a new GolS-controlled operon named gesABC which codes for a CBA efflux system, and establish its role in Au resistance. GesABC can also mediate drug resistance when induced by Au in a GolS-dependent manner, in a strain deleted in the main drug transporter acrAB. The GolS-controlled transcription of gesABC differs from the other GolS-regulated loci. It is activated by gold, but not induced by copper, even in a strain deleted of the main Cu transporter gene copA, which triggers a substantial GolS-dependent induction of golTS and golB. We demonstrate that the Au-dependent induction of gesABC transcription requires higher GolS levels than for the other members of the gol regulon. This correlates with a divergent GolS operator in the gesABC promoter. We propose that the hierarchical induction within the gol regulon allows Salmonella to cope with Au-contaminated environments.
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Affiliation(s)
- Lucas B Pontel
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina
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21
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Campos-Bermudez VA, Leite NR, Krog R, Costa-Filho AJ, Soncini FC, Oliva G, Vila AJ. Biochemical and Structural Characterization of Salmonella typhimurium Glyoxalase II: New Insights into Metal Ion Selectivity,. Biochemistry 2007; 46:11069-79. [PMID: 17764159 DOI: 10.1021/bi7007245] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glyoxalase II is a hydrolytic enzyme part of the glyoxalase system, responsible for detoxifying several cytotoxic compounds employing glutathione. Glyoxalase II belongs to the superfamily of metallo-beta-lactamases, with a conserved motif able to bind up to two metal ions in their active sites, generally zinc. Instead, several eukaryotic glyoxalases II have been characterized with different ratios of iron, zinc, and manganese ions. We have expressed a gene coding for a putative member of this enzyme superfamily from Salmonella typhimurium that we demonstrate, on the basis of its activity, to be a glyoxalase II, named GloB. Recombinant GloB expressed in Escherichia coli was purified with variable amounts of iron, zinc, and manganese. All forms display similar activities, as can be shown from protein expression in minimal medium supplemented with specific metal ions. The crystal structure of GloB solved at 1.4 A shows a protein fold and active site similar to those of its eukaryotic homologues. NMR and EPR experiments also reveal a conserved electronic structure at the metal site. GloB is therefore able to accommodate these different metal ions and to carry out the hydrolytic reaction with similar efficiencies in all cases. The metal promiscuity of this enzyme (in contrast to other members of the same superfamily) can be accounted for by the presence of a conserved Asp residue acting as a second-shell ligand that is expected to increase the hardness of the metal binding site, therefore favoring iron uptake in glyoxalases II.
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Affiliation(s)
- Valeria A Campos-Bermudez
- Instituto de Biología Molecular y Celular de Rosario, IBR-CONICET and Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario S2002LRK, Argentina
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22
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Abstract
Intracellular copper homeostasis in bacteria is maintained as the result of a complex ensemble of cellular processes that in Escherichia coli involve the coordinated action of two systems, cue and cus. In contrast, the pathogenic bacterium Salmonella harbours only the cue regulon, including copA, which is shown here to be transcriptionally controlled by CueR. Mutant strains in the CueR-regulated genes were constructed to characterize the response of Salmonella enterica serovar Typhimurium to high concentrations of extracellular copper under both aerobic and anaerobic conditions. Unlike its counterpart in E. coli, inactivation of cuiD displays the most severe phenotype and is also required for copper tolerance under anaerobic conditions. Deletion of copA has a mild effect in aerobiosis, but strongly impairs survival in the absence of oxygen. In a DeltacopA strain, a second Salmonella-specific P-type ATPase, GolT, can substitute the copper transporter, diminishing the effect of its deletion. The overall results highlight the importance of the cue system for controlling intracellular copper stress. The observed differences between Salmonella and E. coli in handling copper excess may contribute to our understanding of the distinct capability of these related pathogenic bacteria to survive outside the host.
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Affiliation(s)
- Martín Espariz
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina
| | - María E Pérez Audero
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina
| | - Lucas B Pontel
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina
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23
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Cabeza ML, Aguirre A, Soncini FC, Véscovi EG. Induction of RpoS degradation by the two-component system regulator RstA in Salmonella enterica. J Bacteriol 2007; 189:7335-42. [PMID: 17704217 PMCID: PMC2168453 DOI: 10.1128/jb.00801-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial survival in diverse and changing environments relies on the accurate interplay between different regulatory pathways, which determine the design of an adequate adaptive response. The proper outcome depends on a precise gene expression profile generated from the finely tuned and concerted action of transcriptional factors of distinct regulatory hierarchies. Salmonella enterica serovar Typhimurium harbors multiple regulatory systems that are crucial for the bacterium to cope with harsh extra- and intracellular environments. In this work, we found that the expression of Salmonella RstA, a response regulator from the two-component system family, was able to downregulate the expression of three RpoS-controlled genes (narZ, spvA, and bapA). Furthermore, this downregulation was achieved by a reduction in RpoS cellular levels. The alternative sigma factor RpoS is critical for bacterial endurance under the most-stressful conditions, including stationary-phase entrance and host adaptation. Accordingly, RpoS cellular levels are tightly controlled by complex transcriptional, translational, and posttranslational mechanisms. The analysis of each regulatory step revealed that in Salmonella, RstA expression was able to promote RpoS degradation independently of the MviA-ClpXP proteolytic pathway. Additionally, we show that RstA is involved in modulating Salmonella biofilm formation. The fact that the RpoS-modulated genes affected by RstA expression have previously been demonstrated to contribute to Salmonella pathogenic traits, which include biofilm-forming capacity, suggests that under yet unknown conditions, RstA may function as a control point of RpoS-dependent pathways that govern Salmonella virulence.
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Affiliation(s)
- María L Cabeza
- Facultad de Ciencias Bioquímicas y Farmacéuticas (UNR), Departamento de Microbiología, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Suipacha 531, (S2002LRK) Rosario, Argentina
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24
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Abstract
The MerR family is a group of bacterial transcriptional regulators that respond to different environmental stimuli, such as heavy metals, oxidative stress or antibiotics. Here we characterize a new member of this family that is highly selective for Au ions. We show that this Salmonella regulator, named GolS, directly controls the expression of at least two transcriptional units specifically required for Au resistance. By chromosomal mutagenesis, we demonstrated that Au-selectivity is accomplished by a metal-binding motif in GolS. Among the monovalent metal-ion sensing MerR regulators GolS clusters in a branch distant from enterobacterial CueR orthologues. We propose that GolS and its homologues evolved to cope with toxic concentration of Au ion, allowing microorganisms to withstand contaminated environments.
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Affiliation(s)
- Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Universidad Nacional de Rosario, Rosario, Argentina
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25
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Aguirre A, Cabeza ML, Spinelli SV, McClelland M, García Véscovi E, Soncini FC. PhoP-induced genes within Salmonella pathogenicity island 1. J Bacteriol 2006; 188:6889-98. [PMID: 16980492 PMCID: PMC1595516 DOI: 10.1128/jb.00804-06] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The invasive pathogen Salmonella enterica has evolved a sophisticated device that allows it to enter nonphagocytic host cells. This process requires the expression of Salmonella pathogenicity island 1 (SPI-1), which encodes a specialized type III protein secretion system (TTSS). This TTSS delivers a set of effectors that produce a marked rearrangement of the host cytoskeleton, generating a profuse membrane ruffling at the site of interaction, driving bacterial entry. It has been shown that the PhoP/PhoQ two-component system represses the expression of the SPI-1 machinery by down-regulating the transcription of its master regulator, HilA. In this work, we reveal the presence of a PhoP-activated operon within SPI-1. This operon is composed of the orgB and orgC genes, which encode a protein that interacts with the InvC ATPase and a putative effector protein of the TTSS, respectively. Under PhoP-inducing conditions, expression of this operon is directly activated by the phosphorylated form of the response regulator, which recognizes a PhoP box located at the -35 region relative to the transcription start site. Additionally, under invasion-inducing conditions, orgBC expression is driven both by the prgH promoter, induced by the SPI-1 master regulator HilA, and by the directly controlled PhoP/PhoQ promoter. Together, these results indicate that in contrast to the rest of the genes encompassed in the SPI-1 locus, orgBC is expressed during and after Salmonella entry into its host cell, and they suggest a role for the products of this operon after host cell internalization.
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Affiliation(s)
- Andrés Aguirre
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas (UNR), Suipacha 531, S2002LRK Rosario, Argentina
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26
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Abstract
The PhoP/PhoQ two-component system controls the extracellular magnesium depletion response in Salmonella enterica. Previous studies have shown that PhoP is unable to up-regulate its target genes in the absence of PhoQ function. In this work, we demonstrate that PhoP overexpression can substitute for PhoQ- and phosphorylation-dependent activation. Either a high concentration of PhoP or activation via phosphorylation stimulates PhoP self-association.
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Affiliation(s)
- Sergio Lejona
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, 2000 Rosario, Argentina
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27
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Lejona S, Aguirre A, Cabeza ML, García Véscovi E, Soncini FC. Molecular characterization of the Mg2+-responsive PhoP-PhoQ regulon in Salmonella enterica. J Bacteriol 2003; 185:6287-94. [PMID: 14563863 PMCID: PMC219391 DOI: 10.1128/jb.185.21.6287-6294.2003] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The PhoP/PhoQ two-component system controls the extracellular magnesium deprivation response in Salmonella enterica. In addition, several virulence-associated genes that are mainly required for intramacrophage survival during the infection process are under the control of its transcriptional regulation. Despite shared Mg(2+) modulation of the expression of the PhoP-activated genes, no consensus sequence common to all of them could be detected in their promoter regions. We have investigated the transcriptional regulation and the interaction of the response regulator PhoP with the promoter regions of the PhoP-activated loci phoPQ, mgtA, slyB, pmrD, pcgL, phoN, pagC, and mgtCB. A direct repeat of the heptanucleotide sequence (G/T)GTTTA(A/T) was identified as the conserved motif recognized by PhoP to directly control the gene expression of the first five loci, among which the first four are ancestral to enterobacteria. On the other hand, no direct interaction of the response regulator with the promoter of phoN, pagC, or mgtCB was apparent by either in vitro or in vivo assays. These loci are Salmonella specific and were probably acquired by horizontal DNA transfer. Besides, sequence analysis of pag promoters revealed the presence of a conserved PhoP box in 6 out of the 12 genes analyzed. Our results strongly suggest that the expression of a set of Mg(2+)-controlled genes is driven by PhoP via unknown intermediate regulatory mechanisms that could also involve ancillary factors.
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Affiliation(s)
- Sergio Lejona
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
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28
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Castelli ME, Cauerhff A, Amongero M, Soncini FC, Vescovi EG. The H box-harboring domain is key to the function of the Salmonella enterica PhoQ Mg2+-sensor in the recognition of its partner PhoP. J Biol Chem 2003; 278:23579-85. [PMID: 12702718 DOI: 10.1074/jbc.m303042200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In two-component signaling systems, the transduction strategy relies on a conserved His-Asp phosphoryl exchange between the sensor histidine kinase and its cognate response-regulator, and structural and functional consensus motifs are found when comparing either the diverse histidine kinases or response regulators present in a single cell. Therefore, the mechanism that guarantees the specific recognition between partners of an individual pair is essential to unequivocally generate the appropriate adaptive response. Based on sequence alignments with other histidine kinases, we dissected the Salmonella enterica Mg2+-sensor PhoQ in different subdomains and examined by in vivo and in vitro assays its interaction with the associated response regulator PhoP. This signal transduction system allows Salmonella to withstand environmental Mg2+ limitation by triggering gene expression that is vital throughout the infective cycle in the host. Using resonant mirror biosensor technology, we calculated the kinetic and equilibrium binding constants and determined that the His-phosphotransfer domain is essential for the PhoQ specific recognition and interaction with PhoP. Additionally, we show the role of this domain in the bimolecular transphosphorylation and provide evidence that this region undergoes dimerization.
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Affiliation(s)
- María E Castelli
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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29
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Abstract
Iron is essential for all organisms but can be toxic in excess. Iron homeostasis is typically regulated by cytoplasmic iron binding proteins, but here we describe a signal transduction system (PmrA/PmrB) that responds to extracytoplasmic ferric iron. Iron promoted transcription of PmrA-activated genes and resistance to the antibiotic polymyxin in Salmonella. The PmrB protein bound iron via its periplasmic domain which harbors two copies of the sequence ExxE, a motif present in the Saccharomyces FTR1 iron transporter and in mammalian ferritin light chain. A pmrA mutant was hypersensitive to killing by iron but displayed wild-type resistance to a variety of oxidants, suggesting PmrA/PmrB controls a novel pathway mediating the avoidance of iron toxicity.
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Affiliation(s)
- M M Wösten
- Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Castelli ME, García Véscovi E, Soncini FC. The phosphatase activity is the target for Mg2+ regulation of the sensor protein PhoQ in Salmonella. J Biol Chem 2000; 275:22948-54. [PMID: 10807931 DOI: 10.1074/jbc.m909335199] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PhoP/PhoQ two-component system controls the expression of essential virulence traits in the pathogenic bacterium Salmonella enterica serovar Typhimurium. Environmental deprivation of Mg(2+) activates the PhoP/PhoQ signal transduction cascade, which results in an increased expression of genes necessary for survival inside the host. It was previously demonstrated that the interaction of Mg(2+) with the periplasmic domain of PhoQ promotes a conformational change in the sensor protein that leads to the down-regulation of PhoP-activated genes. We have now examined the regulatory effect of Mg(2+) on the putative activities of the membrane-bound PhoQ. We demonstrated that Mg(2+) promotes a phospho-PhoP phosphatase activity in the sensor protein. This activity depends on the intactness of the conserved His-277, suggesting that the phosphatase active site overlaps the H box. The integrity of the N-terminal domain of PhoQ was essential for the induction of the phosphatase activity, because Mg(2+) did not stimulate the release of inorganic phosphate from phospho-PhoP in a fusion protein that lacks this sensing domain. These findings reveal that the sensor PhoQ harbors a phospho-PhoP phosphatase activity, and that this phosphatase activity is the target of the extracellular Mg(2+)-triggered regulation of the PhoP/PhoQ system.
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Affiliation(s)
- M E Castelli
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmacéuticas, Universidad Nacional de Rosario, 2000 Argentina
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Aguirre A, Lejona S, Véscovi EG, Soncini FC. Phosphorylated PmrA interacts with the promoter region of ugd in Salmonella enterica serovar typhimurium. J Bacteriol 2000; 182:3874-6. [PMID: 10851011 PMCID: PMC94567 DOI: 10.1128/jb.182.13.3874-3876.2000] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2000] [Accepted: 04/14/2000] [Indexed: 11/20/2022] Open
Abstract
The Salmonella PmrA-PmrB system controls the expression of genes necessary for polymyxin B resistance. Four loci were previously identified as part of the regulon, and interaction of PmrA with the promoter region of three of them was observed. Here we characterized the interaction of PmrA with the promoter region of ugd, previously suggested to be regulated indirectly by PmrA. Our results indicate that PmrA controls the expression of ugd by interacting with a specific sequence in the promoter region of this gene.
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Affiliation(s)
- A Aguirre
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Abstract
The PmrA-PmrB two-component system of Salmonella typhimurium controls resistance to the peptide antibiotic polymyxin B and to several antimicrobial proteins from human neutrophils. Amino acid substitutions in the regulatory protein PmrA conferring resistance to polymyxin lower the overall negative charge of the lipopolysaccharide (LPS), which results in decreased bacterial binding to cationic polypeptides and increased bacterial survival within human neutrophils. We have now identified three PmrA-activated loci that are required for polymyxin resistance. These loci were previously shown to be necessary for growth on low-Mg2+ solid media, indicating that LPS modifications that mediate polymyxin resistance are responsible for the adaptation to Mg2+-limited environments. Conditions that promote transcription of PmrA-activated genes--growth in mildly acidic pH and micromolar Mg2+ concentrations--increased survival in the presence of polymyxin over 16,000-fold in a wild-type organism but not in a mutant lacking pmrA. Our experiments suggest that low pH and low Mg2+ concentrations may induce expression of PmrA-activated genes within phagocytic cells and promote bacterial resistance to host antimicrobial proteins. We propose that the LPS is a Mg2+ reservoir and that the PmrA-controlled LPS modifications neutralize surface negative charges when Mg2+ is transported into the cytoplasm during growth in Mg2+-limited environments.
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Affiliation(s)
- E A Groisman
- Howard Hughes Medical Institute and Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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33
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Abstract
The PhoP/PhoQ two-component system of Salmonella typhimurium governs transcription of some 25 loci in response to the extracellular concentration of Mg2+. We have now identified one of these loci as pmrCAB, which codes for a two-component system that mediates resistance to the antibiotic polymyxin B. Transcription of seven of 25 PhoP-activated loci was dependent on a functional PmrA protein, the response regulator of the PmrA/PmrB system. Expression of the PmrA-dependent loci was induced by either Mg2+ limitation or mild acidification, whereas transcription of a PmrA-independent gene was activated by Mg2+ limitation but not acid pH. Induction of PmrA-activated genes by Mg2 limitation required the PhoP and PhoQ proteins. In contrast, the acid-mediated activation of PmrA-regulated genes occurred in strains that were missing either one of these proteins. Transcriptional regulation by a cascade of two-component systems allows pathogenic bacteria to express their virulence determinants in response to a broader spectrum of environmental cues.
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Affiliation(s)
- F C Soncini
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Soncini FC, García Véscovi E, Solomon F, Groisman EA. Molecular basis of the magnesium deprivation response in Salmonella typhimurium: identification of PhoP-regulated genes. J Bacteriol 1996; 178:5092-9. [PMID: 8752324 PMCID: PMC178303 DOI: 10.1128/jb.178.17.5092-5099.1996] [Citation(s) in RCA: 274] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The PhoP-PhoQ two-component system is essential for virulence in Salmonella typhimurium. This system controls expression of some 40 different proteins, yet most PhoP-regulated genes remain unknown. To identify PhoP-regulated genes, we isolated a library of 50,000 independent lac gene transcriptional fusion strains and investigated whether production of beta-galactosidase was regulated by PhoP. We recovered 47 lac gene fusions that were activated and 7 that were repressed when PhoP was expressed. Analysis of 40 such fusions defined some 30 loci, including mgtA and mgtCB, which encode two of the three Mg2+ uptake systems of S. typhimurium; ugd, encoding UDP-glucose dehydrogenase; phoP, indicative that the phoPQ operon is autoregulated; and an open reading frame encoding a protein with sequence similarity to VanX, a dipeptidase required for resistance to vancomycin. Transcription of PhoP-activated genes was regulated by the levels of Mg2+ in a PhoP-dependent manner. Strains with mutations in phoP or phoQ were defective for growth in low-Mg2+ media. The mgtA and mgtCB mutants reached lower optical densities than the wild-type strain in low-Mg2+ liquid media but displayed normal growth on low-Mg2+ solid media. Six PhoP-activated genes were identified as essential to form colonies on low-Mg'+ solid media. Cumulatively, our experiments establish that the PhoP-PhoQ system governs the adaptation to magnesium-limiting environments.
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Affiliation(s)
- F C Soncini
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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35
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Ochman H, Soncini FC, Solomon F, Groisman EA. Identification of a pathogenicity island required for Salmonella survival in host cells. Proc Natl Acad Sci U S A 1996; 93:7800-4. [PMID: 8755556 PMCID: PMC38828 DOI: 10.1073/pnas.93.15.7800] [Citation(s) in RCA: 505] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have identified a region unique to the Salmonella typhimurium chromosome that is essential for virulence in mice. This region harbors at least three genes: two (spiA and spiB) encode products that are similar to proteins found in type III secretion systems, and a third (spiR) encodes a putative regulator. A strain with a mutation in spiA was unable to survive within macrophages but displayed wild-type levels of epithelial cell invasion. The culture supernatants of the spi mutants lacked a modified form of flagellin, which was present in the supernatant of the wild-type strain. This suggests that the Spi secretory apparatus exports a protease, or a protein that can alter the activity of a secreted protease. The "pathogenicity island" harboring the spi genes may encode the virulence determinants that set Salmonella apart from other enteric pathogens.
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Affiliation(s)
- H Ochman
- Department of Biology, University of Rochester, NY 14627, USA
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36
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Abstract
Ions are not traditionally thought to act as first messengers in signal transduction cascades. However, while searching for genes regulated by the PhoP/PhoQ virulence regulatory system of Salmonella typhimurium, we recovered two loci whose expression is controlled by the concentration of Mg2+. To determine whether Mg2+ is the signal modulating the whole PhoP/PhoQ system, we evaluated the gene expression pattern of six PhoP-activated genes. Growth in physiological concentrations of divalent cations repressed transcription of PhoP-activated genes and rendered wild-type Salmonella phenotypically PhoP-. Mg2+ changed the conformation of the periplasmic domain of PhoQ, identifying this protein as a Mg2+ sensor. A mutation in the sensing domain of PhoQ altered the set point for Mg2+ and rendered Salmonella avirulent.
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Affiliation(s)
- E García Véscovi
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110, USA
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37
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Abstract
The Salmonella typhimurium PhoP-PhoQ two-component regulatory system controls the expression of several genes, some of which are necessary for virulence. During a screening for PhoP-regulated genes, we identified the phoPQ operon as a PhoP-activated locus. beta-Galactosidase activity originating from phoPQ-lac transcriptional fusions required the presence of both the transcriptional regulator PhoP and its cognate sensor-kinase PhoQ. At low concentrations, PhoQ stimulated expression of phoPQ-lac transcriptional fusions. However, larger amounts of PhoQ protein without a concomitant increase in PhoP failed to activate phoPQ-lac fusions. Two different transcripts are produced from the phoPQ operon during exponential growth. These transcripts define two promoters: phoPp1, which requires both PhoP and PhoQ for activity and which is environmentally regulated, and phoPp2, which remains active in the absence of PhoP and PhoQ but which is slightly stimulated by these proteins. The pattern of transcriptional autoregulation was also observed at the protein level with anti-PhoP antibodies. In sum, autoregulation of the phoPQ operon provides several levels of control for the PhoP-PhoQ regulon. First, environmental signals would stimulate PhoQ to phosphorylate the PhoP protein that is produced at basal levels from the PhoP-PhoQ-independent promoter. Then, phospho-PhoP would activate transcription of phoPp1, resulting in larger amounts of PhoP and PhoQ and increased expression of PhoP-activated genes. A return to basal levels could be mediated by a posttranscriptional mechanism by which translation of the mRNA produced from phoPp1 is inhibited.
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Affiliation(s)
- F C Soncini
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Viale AM, Arakaki AK, Soncini FC, Ferreyra RG. Evolutionary relationships among eubacterial groups as inferred from GroEL (chaperonin) sequence comparisons. Int J Syst Bacteriol 1994; 44:527-33. [PMID: 7520741 DOI: 10.1099/00207713-44-3-527] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The essential GroEL proteins represent a subset of molecular chaperones ubiquitously distributed among species of the eubacterial lineage, as well as in eukaryote organelles. We employed these highly conserved proteins to infer eubacterial phylogenies. GroEL from the species analyzed clustered in distinct groups in evolutionary trees drawn by either the distance or the parsimony method, which were in general agreement with those found by 16S rRNA comparisons (i.e., proteobacteria, chlamydiae, bacteroids, spirochetes, firmicutes [gram-positive bacteria], and cyanobacteria-chloroplasts). Moreover, the analysis indicated specific relationships between some of the aforementioned groups which appeared not to be clearly defined or controversial in rRNA-based phylogenetic studies. For instance, a monophyletic origin for the low-G+C and high-G+C subgroups among the firmicutes, as well as their specific relationship to the cyanobacteria-chloroplasts, was inferred. The general observations suggest that GroEL proteins provide valuable evolutionary tools for defining evolutionary relationships among the eubacterial lineage of life.
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Affiliation(s)
- A M Viale
- Departmento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
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39
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Abstract
Salmonella typhimurium is a facultative intracellular pathogen that is able to survive in a wide variety of inhibitory and nutritionally deprived host environments. The ability to survive under such hostile conditions, which are often encountered during the course of infection, contributes to its pathogenic properties. Some of the virulence determinants of S. typhimurium are under the transcriptional control of the PhoPQ two-component regulatory system. Several virulence phenotypes have been associated with mutations in the phoPQ operon including the inability to survive within macrophages and increased susceptibility to antimicrobial peptides and acid pH. Only 25% of PhoP-modulated genes are involved in virulence and the phoPQ operon is present in both pathogenic and non-pathogenic microbes. These data suggest that PhoP is not exclusively involved in virulence and that it is required for the physiological control of activities common to other bacteria.
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Affiliation(s)
- E Garcia Véscovi
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
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40
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Ferreyra RG, Soncini FC, Viale AM. Cloning, characterization, and functional expression in Escherichia coli of chaperonin (groESL) genes from the phototrophic sulfur bacterium Chromatium vinosum. J Bacteriol 1993; 175:1514-23. [PMID: 8444812 PMCID: PMC193240 DOI: 10.1128/jb.175.5.1514-1523.1993] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A recombinant lambda phage which was able to propagate in groE mutants of Escherichia coli was isolated from a Chromatium vinosum genomic DNA library. A 4-kbp SalI DNA fragment, isolated from this phage and subcloned in plasmid vectors, carried the C. vinosum genes that allowed lambda growth in these mutants. Sequencing of this fragment indicated the presence of two open reading frames encoding polypeptides of 97 and 544 amino acids, respectively, which showed high similarity to the molecular chaperones GroES and GroEL, respectively, from several eubacteria and eukaryotic organelles. Expression of the cloned C. vinosum groESL genes in E. coli was greatly enhanced when the cells were transferred to growth temperatures that induce the heat shock response in this host. Coexpression in E. coli of C. vinosum groESL genes and the cloned ribulose bisphosphate carboxylase/oxygenase genes from different phototrophic bacteria resulted in an enhanced assembly of the latter enzymes. These results indicate that the cloned DNA fragment encodes C. vinosum chaperonins, which serve in the assembly process of oligomeric proteins. Phylogenic analysis indicates a close relationship between C. vinosum chaperonins and their homologs present in pathogenic species of the gamma subdivision of the eubacterial division Proteobacteria.
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Affiliation(s)
- R G Ferreyra
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
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Soncini FC, Vallejos RH. The chloroplast reductase-binding protein is identical to the 16.5-kDa polypeptide described as a component of the oxygen-evolving complex. J Biol Chem 1989; 264:21112-5. [PMID: 2687273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The N-terminal sequence of the spinach chloroplast reductase-binding protein was determined. The sequence is the same one of a 16.5-kDa polypeptide described as a component of the oxygen-evolving system. Antibodies against both proteins are equivalent as shown by immunoblots, Ouchterlony assays, precipitation of reductase-binding protein complex, and agglutination of thylakoids partially depleted of reductase. These results suggest both proteins are identical. Exposure of the binding protein on the stromal side of thylakoids is supported by agglutination of thylakoids partially depleted of reductase, proteolysis by trypsin, and by accessibility to Fab of anti-binding protein. The latter prevents rebinding of reductase supporting the functional role of the binding protein (16.5 kDa).
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Affiliation(s)
- F C Soncini
- Centro de Estudios Fotosintéticos y Bioquímicos (Consejo Nacional de Investigaciones Ciencíficas y Técnicas, Fund. M. Lillo, Universidad Nacional de Rosario, Rosario, Argentina
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Soncini FC, Vallejos RH. Immunodetection of the Ferredoxin-NADP Oxidoreductase-Binding Protein Complex in Thylakoids of Different Higher Plant Species. Plant Physiol 1989; 90:372-5. [PMID: 16666777 PMCID: PMC1061729 DOI: 10.1104/pp.90.2.372] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Monospecific polyclonal antibodies against thylakoid ferredoxin-NADP(+) oxidoreductase and its binding protein from Spinacia oleracea were used to detect the presence of these proteins in different higher plants, including C(3), C(4), and Crassulacean acid metabolism species. A remarkable conservation of antigenic determinants in all the species analyzed was demonstrated for both the reductase and its binding protein. The association of these polypeptides in a complex was detected by immunoprecipitation.
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Affiliation(s)
- F C Soncini
- Centro de Estudios Fotosintéticos y Bioquímicos (CONICET, F.M.Lillo, U.N.R.), Suipacha 531, 2000 Rosario, Argentina
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Serrano A, Soncini FC, Vallejos RH. Localization and Quantitative Determination of Ferredoxin-NADP Oxidoreductase, a Thylakoid-Bound Enzyme in the Cyanobacterium Anabaena sp. Strain 7119. Plant Physiol 1986; 82:499-502. [PMID: 16665058 PMCID: PMC1056148 DOI: 10.1104/pp.82.2.499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Thylakoid membrane preparations obtained from mechanically disrupted (sonicated) cells of the cyanobacterium Anabaena sp. strain 7119 show a membrane-bound ferredoxin-NADP(+) oxidoreductase (EC 1.18.1.2) as determined either by specific antibodies or by using the ferredoxin-dependent NADPH-cytochrome c reductase activity, which is a specific test for this enzyme. However, in contrast with higher plant thylakoids, a low yield of the cyanobacterial reductase-only about 20% of the total amount of this protein estimated in whole cell homogenates-was obtained as a membrane-bound form when Mg(2+) was present during the disruption treatment. It is noteworthy that the addition of water-soluble nonionic polymers, namely polyethylene glycol and polyyinylpyrrolidone, dramatically increased the yield of the thylakoid-bound reductase, reaching values up to 80 to 85% of the total enzyme. Using these thylakoid membrane preparations, a quantitative determination of the reductase has been performed for the first time for cyanobacterial thylakoids. The value determined by immunoelectrophoresis-from 8 to 10 nanomoles per micromole of chlorophyll-is clearly higher than those reported for chloroplast thylakoids.
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Affiliation(s)
- A Serrano
- Centro de Estudios Fotosintéticos y Bioquímicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Fundación Miguel Lillo, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
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