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易 海, 高 兴, 罗 果, 徐 鹏, 王 欢. [Prokaryotic Expression and Bioinformatic Analysis of Rv3432c From Mycobacterium tuberculosis]. SICHUAN DA XUE XUE BAO. YI XUE BAN = JOURNAL OF SICHUAN UNIVERSITY. MEDICAL SCIENCE EDITION 2024; 55:330-336. [PMID: 38645872 PMCID: PMC11026876 DOI: 10.12182/20240360401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Indexed: 04/23/2024]
Abstract
Objective To express the protein enconded by the Rv3432c gene of Mycobacterium tuberculosis (M.tb) in vitro by prokaryotic expression, to analyze the structure of the Rv3432c protein by using bioinformatics software, and to explore for new drug targets against M.tb. Methods The Rv3432c gene was amplified by PCR using the genomic DNA of the inactivated M.tb strain H37Rv as the template and a recombinant plasmid was constructed with the expression vector pET-28a. The expression products were analyzed by SDS-PAGE and purified using affinity chromatography. The biological properties of Rv3432c were analyzed with Protparam, the Pfam online tool, SOMPA, Protscale, TMHMM Signalp 6.0, NetPhos3.1, SUMOsp 2.0, and SWISS-MODEL. Results pET-28a-Rv3432c recombinant plasmid sequencing results were fully consistent with those of the target gene. SDS-PAGE analysis showed that the fusion protein existed in the form of a soluble protein with a relative molecular mass of about 55×103, which matched the expected size. ProtParam analysis showed that the Rv3432c protein was hydrophilic (showing a GRAVY value of -0.079). Rv3432c was a protein with no transmembrane structural domains or signal peptide. The secondary structure of Rv3432c mainly consisted of random coils (39.78%) and α-helix (39.57%) and was relatively loosely structured. Conclusion We successfully constructed a prokaryotic expression plasmid of the Rv3432c protein and analyzed its structure using bioinformatics, laying the foundation for further research on the role of Rv3432c in the pathogenesis and progression of tuberculosis as well as the identification of new drug targets against M.tb.
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Affiliation(s)
- 海波 易
- 遵义医科大学贵州省普通高等学校传染病与生物安全特色重点实验室 (遵义 563099)Key Laboratory of Infectious Disease & Bio-safety, Provincial Department of Education, Zunyi Medical University, Zunyi 563099, China
| | - 兴红 高
- 遵义医科大学贵州省普通高等学校传染病与生物安全特色重点实验室 (遵义 563099)Key Laboratory of Infectious Disease & Bio-safety, Provincial Department of Education, Zunyi Medical University, Zunyi 563099, China
| | - 果 罗
- 遵义医科大学贵州省普通高等学校传染病与生物安全特色重点实验室 (遵义 563099)Key Laboratory of Infectious Disease & Bio-safety, Provincial Department of Education, Zunyi Medical University, Zunyi 563099, China
| | - 鹏 徐
- 遵义医科大学贵州省普通高等学校传染病与生物安全特色重点实验室 (遵义 563099)Key Laboratory of Infectious Disease & Bio-safety, Provincial Department of Education, Zunyi Medical University, Zunyi 563099, China
| | - 欢 王
- 遵义医科大学贵州省普通高等学校传染病与生物安全特色重点实验室 (遵义 563099)Key Laboratory of Infectious Disease & Bio-safety, Provincial Department of Education, Zunyi Medical University, Zunyi 563099, China
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The Retrospective on Atypical Brucella Species Leads to Novel Definitions. Microorganisms 2022; 10:microorganisms10040813. [PMID: 35456863 PMCID: PMC9025488 DOI: 10.3390/microorganisms10040813] [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: 02/28/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 02/01/2023] Open
Abstract
The genus Brucella currently comprises twelve species of facultative intracellular bacteria with variable zoonotic potential. Six of them have been considered as classical, causing brucellosis in terrestrial mammalian hosts, with two species originated from marine mammals. In the past fifteen years, field research as well as improved pathogen detection and typing have allowed the identification of four new species, namely Brucella microti, Brucella inopinata, Brucella papionis, Brucella vulpis, and of numerous strains, isolated from a wide range of hosts, including for the first time cold-blooded animals. While their genome sequences are still highly similar to those of classical strains, some of them are characterized by atypical phenotypes such as higher growth rate, increased resistance to acid stress, motility, and lethality in the murine infection model. In our review, we provide an overview of state-of-the-art knowledge about these novel Brucella sp., with emphasis on their phylogenetic positions in the genus, their metabolic characteristics, acid stress resistance mechanisms, and their behavior in well-established in cellulo and in vivo infection models. Comparison of phylogenetic classification and phenotypical properties between classical and novel Brucella species and strains finally lead us to propose a more adapted terminology, distinguishing between core and non-core, and typical versus atypical brucellae, respectively.
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de la Garza-García JA, Ouahrani-Bettache S, Lyonnais S, Ornelas-Eusebio E, Freddi L, Al Dahouk S, Occhialini A, Köhler S. Comparative Genome-Wide Transcriptome Analysis of Brucella suis and Brucella microti Under Acid Stress at pH 4.5: Cold Shock Protein CspA and Dps Are Associated With Acid Resistance of B. microti. Front Microbiol 2021; 12:794535. [PMID: 34966374 PMCID: PMC8710502 DOI: 10.3389/fmicb.2021.794535] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/12/2021] [Indexed: 11/13/2022] Open
Abstract
Brucellae are facultative intracellular coccobacilli causing brucellosis, one of the most widespread bacterial zoonosis affecting wildlife animals, livestock and humans. The genus Brucella comprises classical and atypical species, such as Brucella suis and Brucella microti, respectively. The latter is characterized by increased metabolic activity, fast growth rates, and extreme acid resistance at pH 2.5, suggesting an advantage for environmental survival. In addition, B. microti is more acid-tolerant than B. suis at the intermediate pH of 4.5. This acid-resistant phenotype of B. microti may have major implications for fitness in soil, food products and macrophages. Our study focused on the identification and characterization of acid resistance determinants of B. suis and B. microti in Gerhardt's minimal medium at pH 4.5 and 7.0 for 20 min and 2 h by comparative RNA-Seq-based transcriptome analysis, validated by RT-qPCR. Results yielded a common core response in both species with a total of 150 differentially expressed genes, and acidic pH-dependent genes regulated specifically in each species. The identified core response mechanisms comprise proton neutralization or extrusion from the cytosol, participating in maintaining physiological intracellular pH values. Differential expression of 441 genes revealed species-specific mechanisms in B. microti with rapid physiological adaptation to acid stress, anticipating potential damage to cellular components and critical energy conditions. Acid stress-induced genes encoding cold shock protein CspA, pseudogene in B. suis, and stress protein Dps were associated with survival of B. microti at pH 4.5. B. suis response with 284 specifically regulated genes suggested increased acid stress-mediated protein misfolding or damaging, triggering the set-up of repair strategies countering the consequences rather than the origin of acid stress and leading to subsequent loss of viability. In conclusion, our work supports the hypothesis that increased acid stress resistance of B. microti is based on selective pressure for the maintenance of functionality of critical genes, and on specific differential gene expression, resulting in rapid adaptation.
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Affiliation(s)
- Jorge A de la Garza-García
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University Montpellier, INSERM, Montpellier, France
| | - Safia Ouahrani-Bettache
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University Montpellier, INSERM, Montpellier, France
| | | | - Erika Ornelas-Eusebio
- Unité des Zoonoses Bactériennes and Unité d'Epidémiologie, Laboratoire de Santé Animale, ANSES, University Paris-Est, Maisons-Alfort, France
| | - Luca Freddi
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University Montpellier, INSERM, Montpellier, France
| | | | - Alessandra Occhialini
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University Montpellier, INSERM, Montpellier, France
| | - Stephan Köhler
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University Montpellier, INSERM, Montpellier, France
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Roop RM, Barton IS, Hopersberger D, Martin DW. Uncovering the Hidden Credentials of Brucella Virulence. Microbiol Mol Biol Rev 2021; 85:e00021-19. [PMID: 33568459 PMCID: PMC8549849 DOI: 10.1128/mmbr.00021-19] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.
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Affiliation(s)
- R Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ian S Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Dariel Hopersberger
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Daniel W Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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Kornspan D, Zahavi T, Salmon-Divon M. The Acidic Stress Response of the Intracellular Pathogen Brucella melitensis: New Insights from a Comparative, Genome-Wide Transcriptome Analysis. Genes (Basel) 2020; 11:genes11091016. [PMID: 32872264 PMCID: PMC7563570 DOI: 10.3390/genes11091016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/23/2020] [Accepted: 08/25/2020] [Indexed: 11/30/2022] Open
Abstract
The intracellular pathogenic bacteria belonging to the genus Brucella must cope with acidic stress as they penetrate the host via the gastrointestinal route, and again during the initial stages of intracellular infection. A transcription-level regulation has been proposed to explain this but the specific molecular mechanisms are yet to be determined. We recently reported a comparative transcriptomic analysis of the attenuated vaccine Brucella melitensis strain Rev.1 against the virulent strain 16M in cultures grown under either neutral or acidic conditions. Here, we re-analyze the RNA-seq data of 16M from our previous study and compare it to published transcriptomic data of this strain from both an in cellulo and an in vivo model. We identify 588 genes that are exclusively differentially expressed in 16M grown under acidic versus neutral pH conditions, including 286 upregulated genes and 302 downregulated genes that are not differentially expressed in either the in cellulo or the in vivo model. Of these, we highlight 13 key genes that are known to be associated with a bacterial response to acidic stress and, in our study, were highly upregulated under acidic conditions. These genes provide new molecular insights into the mechanisms underlying the acid-resistance of Brucella within its host.
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Affiliation(s)
- David Kornspan
- Department of Bacteriology, Kimron Veterinary Institute, Bet Dagan 50250, Israel
- Correspondence: ; Tel.: +972-3-968-1745
| | - Tamar Zahavi
- Genomic Bioinformatics Laboratory, Department of Molecular Biology, Ariel University, Ariel 40700, Israel; (T.Z.); (M.S.-D.)
| | - Mali Salmon-Divon
- Genomic Bioinformatics Laboratory, Department of Molecular Biology, Ariel University, Ariel 40700, Israel; (T.Z.); (M.S.-D.)
- Adelson School of Medicine, Ariel University, Ariel 40700, Israel
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Ouahrani-Bettache S, Jiménez De Bagüés MP, De La Garza J, Freddi L, Bueso JP, Lyonnais S, Al Dahouk S, De Biase D, Köhler S, Occhialini A. Lethality of Brucella microti in a murine model of infection depends on the wbkE gene involved in O-polysaccharide synthesis. Virulence 2020; 10:868-878. [PMID: 31635539 PMCID: PMC6844557 DOI: 10.1080/21505594.2019.1682762] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Brucella microti was isolated a decade ago from wildlife and soil in Europe. Compared to the classical Brucella species, it exhibits atypical virulence properties such as increased growth in human and murine macrophages and lethality in experimentally infected mice. A spontaneous rough (R) mutant strain, derived from the smooth reference strain CCM4915T, showed increased macrophage colonization and was non-lethal in murine infections. Whole-genome sequencing and construction of an isogenic mutant of B. microti and Brucella suis 1330 revealed that the R-phenotype was due to a deletion in a single gene, namely wbkE (BMI_I539), encoding a putative glycosyltransferase involved in lipopolysaccharide (LPS) O-polysaccharide biosynthesis. Complementation of the R-strains with the wbkE gene restored the smooth phenotype and the ability of B. microti to kill infected mice. LPS with an intact O-polysaccharide is therefore essential for lethal B. microti infections in the murine model, demonstrating its importance in pathogenesis.
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Affiliation(s)
| | - María P Jiménez De Bagüés
- Unidad de Tecnología en Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria, Instituto Agroalimentario de Aragón, Universidad de Zaragoza, Zaragoza, Spain
| | | | - Luca Freddi
- IRIM, CNRS, University Montpellier, INSERM, Montpellier, France
| | - Juan P Bueso
- Laboratorio Agroalimentario, Gobierno de Aragón, Zaragoza, Spain
| | | | - Sascha Al Dahouk
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Daniela De Biase
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Laboratory affiliated to the Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Latina, Italy
| | - Stephan Köhler
- IRIM, CNRS, University Montpellier, INSERM, Montpellier, France
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Jaÿ M, Freddi L, Mick V, Durand B, Girault G, Perrot L, Taunay B, Vuilmet T, Azam D, Ponsart C, Zanella G. Brucella microti-like prevalence in French farms producing frogs. Transbound Emerg Dis 2019; 67:617-625. [PMID: 31574213 DOI: 10.1111/tbed.13377] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 09/06/2019] [Accepted: 09/19/2019] [Indexed: 11/30/2022]
Abstract
In the last 10 years, many atypical novel members of Brucella species have been reported, including several Brucella inopinata-like strains in wild-caught and "exotic" amphibians from various continents. In 2017, a strain of Brucella was isolated for the first time in animals from a French farm producing frogs-Pelophylax ridibundus-for human consumption and identified as B. microti-like. Following this first isolation, investigations were performed in this farm as well as in the farm of the research unit that provided the domestic frog strain to estimate the prevalence of B. microti-like infection and its presence in the surrounding environment. Farming practices were investigated and samples including frogs at different development stages, surface tank swabs, water, feed and soil were analysed by real-time PCR and bacteriological methods. High B. microti-like prevalence values (higher than 90%) were obtained in frog samples in the commercial farm, and its presence was highlighted in the environmental samples except feed. In the research unit farm, B. microti-like species was also isolated and detected in frog and environmental samples. These results show that B. microti-like organisms are able to colonize amphibians and persist in their environment. Its presence could constitute a possible risk for consumers and workers proving the importance of assessing the zoonotic and pathogenic potentials of these new and atypical Brucella species.
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Affiliation(s)
- Maryne Jaÿ
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Luca Freddi
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Virginie Mick
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Benoit Durand
- Epidemiology Unit, Laboratory for Animal Health, ANSES, University Paris Est, Maisons-Alfort, France
| | - Guillaume Girault
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Ludivine Perrot
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Benoit Taunay
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Thomas Vuilmet
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Didier Azam
- U3E, Ecologie et Ecotoxicologie aquatique, INRA, pôle Gest'Aqua, Rennes, France
| | - Claire Ponsart
- EU/OIE/FAO & National Reference Laboratory for Brucellosis, Animal Health Laboratory, ANSES, Paris-Est University, Maisons-Alfort, France
| | - Gina Zanella
- Epidemiology Unit, Laboratory for Animal Health, ANSES, University Paris Est, Maisons-Alfort, France
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Li Q, Tao Q, Teixeira JS, Shu-Wei Su M, Gänzle MG. Contribution of glutaminases to glutamine metabolism and acid resistance in Lactobacillus reuteri and other vertebrate host adapted lactobacilli. Food Microbiol 2019; 86:103343. [PMID: 31703887 DOI: 10.1016/j.fm.2019.103343] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 09/17/2019] [Accepted: 09/27/2019] [Indexed: 01/13/2023]
Abstract
The bacterial conversion of glutamine to glutamate is catalyzed by glutamine-amidotransferases or glutaminases. Glutamine deamination contributes to the formation of the bioactive metabolites glutamate, γ-aminobutyrate (GABA) and γ-glutamyl peptides, and to acid resistance. This study aimed to investigate the distribution of glutaminase(s) in lactobacilli, and to evaluate their contribution in L. reuteri to amino acid metabolism and acid resistance. Phylogenetic analysis of the glutaminases gls1, gls2 and gls3 in the genus Lactobacillus demonstrated that glutaminase is exclusively present in host-adapted species of lactobacilli. The disruption gls1, gls2 and gls3 in L. reuteri 100-23 had only a limited effect on the conversion of glutamine to glutamate, GABA, or γ-glutamyl peptides in sourdough. The disruption of all glutaminases in L. reuteri 100-23Δgls1Δgls2Δgls3 but not disruption of gls2 and gls3 eliminated the protective effect of glutamine on the survival of the strain at pH 2.5. Glutamine also enhanced acid resistance of L. reuteri 100-23ΔgadB and L. taiwanensis 107q, strains without glutamate decarboxylase activity. Taken together, the study demonstrates that glutaminases of lactobacilli do not contribute substantially to glutamine metabolism but enhance acid resistance. Their exclusive presence in host-adapted lactobacilli provides an additional link between the adaptation of lactobacilli to specific habitats and their functionality when used as probiotics and starter cultures.
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Affiliation(s)
- Qing Li
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - QianYing Tao
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - Jaunana S Teixeira
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - Marcia Shu-Wei Su
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - Michael G Gänzle
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada; Hubei University of Technology, College of Bioengineering and Food Science, Wuhan, Hubei, PR China.
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Pennacchietti E, D'Alonzo C, Freddi L, Occhialini A, De Biase D. The Glutaminase-Dependent Acid Resistance System: Qualitative and Quantitative Assays and Analysis of Its Distribution in Enteric Bacteria. Front Microbiol 2018; 9:2869. [PMID: 30498489 PMCID: PMC6250119 DOI: 10.3389/fmicb.2018.02869] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 11/08/2018] [Indexed: 12/22/2022] Open
Abstract
Neutralophilic bacteria have developed several strategies to overcome the deleterious effects of acid stress. In particular, the amino acid-dependent systems are widespread, with their activities overlapping, covering a rather large pH range, from 6 to <2. Recent reports showed that an acid resistance (AR) system relying on the amino acid glutamine (AR2_Q), the most readily available amino acid in the free form, is operative in Escherichia coli, Lactobacillus reuteri, and some Brucella species. This system requires a glutaminase active at acidic pH and the antiporter GadC to import L-glutamine and export either glutamate (the glutamine deamination product) or GABA. The latter occurs when the deamination of glutamine to glutamate, via acid-glutaminase (YbaS/GlsA), is coupled to the decarboxylation of glutamate to GABA, via glutamate decarboxylase (GadB), a structural component of the glutamate-dependent AR (AR2) system, together with GadC. Taking into account that AR2_Q could be widespread in bacteria and that until now assays based on ammonium ion detection were typically employed, this work was undertaken with the aim to develop assays that allow a straightforward identification of the acid-glutaminase activity in permeabilized bacterial cells (qualitative assay) as well as a sensitive method (quantitative assay) to monitor in the pH range 2.5-4.0 the transport of the relevant amino acids in vivo. The qualitative assay is colorimetric, rapid and reliable and provides several additional information, such as co-occurrence of AR2 and AR2_Q in the same bacterial species and assessment of the growth conditions that support maximal expression of glutaminase at acidic pH. The quantitative assay is HPLC-based and allows to concomitantly measure the uptake of glutamine and the export of glutamate and/or GABA via GadC in vivo and depending on the external pH. Finally, an extensive bioinformatic genome analysis shows that the gene encoding the glutaminase involved in AR2_Q is often nearby or in operon arrangement with the genes coding for GadC and GadB. Overall, our results indicate that AR2_Q is likely to be of prominent importance in the AR of enteric bacteria and that it modulates the enzymatic as well as antiport activities depending on the imposed acidic stress.
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Affiliation(s)
- Eugenia Pennacchietti
- Department of Medico-Surgical Sciences and Biotechnologies, Laboratory Affiliated to the Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Latina, Italy
| | - Chiara D'Alonzo
- Department of Medico-Surgical Sciences and Biotechnologies, Laboratory Affiliated to the Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Latina, Italy
| | - Luca Freddi
- Institut de Recherche en Infectiologie de Montpellier, CNRS, University of Montpellier, Montpellier, France
| | - Alessandra Occhialini
- Institut de Recherche en Infectiologie de Montpellier, CNRS, University of Montpellier, Montpellier, France
| | - Daniela De Biase
- Department of Medico-Surgical Sciences and Biotechnologies, Laboratory Affiliated to the Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Latina, Italy
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