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Farman MR, Petráčková D, Kumar D, Držmíšek J, Saha A, Čurnová I, Čapek J, Hejnarová V, Amman F, Hofacker I, Večerek B. Avirulent phenotype promotes Bordetella pertussis adaptation to the intramacrophage environment. Emerg Microbes Infect 2023; 12:e2146536. [PMID: 36357372 PMCID: PMC9858536 DOI: 10.1080/22221751.2022.2146536] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Bordetella pertussis, the causative agent of whooping cough, is an extracellular, strictly human pathogen. However, it has been shown that B. pertussis cells can escape phagocytic killing and survive in macrophages upon internalization. Our time-resolved RNA-seq data suggest that B. pertussis efficiently adapts to the intramacrophage environment and responds to host bactericidal activities. We show that this adaptive response is multifaceted and, surprisingly, related to the BvgAS two-component system, a master regulator of virulence. Our results show that the expression of this regulatory circuit is downregulated upon internalization. Moreover, we demonstrate that the switch to the avirulent Bvg- phase augments a very complex process based on the adjustment of central and energy metabolism, cell wall reinforcement, maintenance of appropriate redox and metal homeostasis, and repair of damaged macromolecules. Nevertheless, not all observed effects could be simply attributed to the transition to Bvg- phase, suggesting that additional regulators are involved in the adaptation to the intramacrophage environment. Interestingly, a large number of genes required for the metabolism of sulphur were strongly modulated within macrophages. In particular, the mutant lacking two genes encoding cysteine dioxygenases displayed strongly attenuated cytotoxicity toward THP-1 cells. Collectively, our results suggest that intracellular B. pertussis cells have adopted the Bvg- mode to acclimate to the intramacrophage environment and respond to antimicrobial activities elicited by THP-1 cells. Therefore, we hypothesize that the avirulent phase represents an authentic phenotype of internalized B. pertussis cells.
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Affiliation(s)
- Mariam R. Farman
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Denisa Petráčková
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Dilip Kumar
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Jakub Držmíšek
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Argha Saha
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Ivana Čurnová
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Jan Čapek
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Václava Hejnarová
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic
| | - Fabian Amman
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Ivo Hofacker
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Branislav Večerek
- Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, Prague, Czech Republic, Branislav Večerek Czech Academy of Sciences, Laboratory of Post-transcriptional Control of Gene Expression, Institute of Microbiology, 14220Prague, Czech Republic
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2
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Zhao Y, Liu Y, Li N, Muhammad M, Gong S, Ju J, Cai T, Wang J, Zhao B, Liu D. Significance of broad-spectrum racemases for the viability and pathogenicity of Aeromonas hydrophila. Future Microbiol 2022; 17:251-265. [PMID: 35152710 DOI: 10.2217/fmb-2021-0112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To investigate the function of broad-spectrum racemases in Aeromonas hydrophila (BsrA). Results: The A. hydrophila gene encoding BsrA (bsr) mutants (AHΔbsr) exhibited a significant decrease in growth, motility, extracellular protease production and biofilm formation compared with the wild-type. Furthermore, bsr gene knockout instigated cell wall damage compared with the wild-type strains. The survival rate and replication capability in the blood and organs of the AHΔbsr-infected mice were significantly decreased. The degree of tissue injury in the AHΔbsr-infected group was lower than that of the wild-type-infected group. Moreover, there was a significant decrease in the expression of 12 AHΔbsr virulence genes. Conclusion: The bsr gene is essential for the viability and virulence of A. hydrophila.
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Affiliation(s)
- Yi Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yaoyao Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Na Li
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Murtala Muhammad
- Department of Biochemistry, Kano University of Science and Technology, Wudil, 713281, Nigeria
| | - Siyu Gong
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jiansong Ju
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Tongxuan Cai
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jialu Wang
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Baohua Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Dong Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
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3
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Black KA, Duan L, Mandyoli L, Selbach BP, Xu W, Ehrt S, Sacchettini JC, Rhee KY. Metabolic bifunctionality of Rv0812 couples folate and peptidoglycan biosynthesis in Mycobacterium tuberculosis. J Exp Med 2021; 218:212052. [PMID: 33950161 PMCID: PMC8105722 DOI: 10.1084/jem.20191957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 02/16/2021] [Accepted: 03/30/2021] [Indexed: 11/04/2022] Open
Abstract
Comparative sequence analysis has enabled the annotation of millions of genes from organisms across the evolutionary tree. However, this approach has inherently biased the annotation of phylogenetically ubiquitous, rather than species-specific, functions. The ecologically unusual pathogen Mycobacterium tuberculosis (Mtb) has evolved in humans as its sole reservoir and emerged as the leading bacterial cause of death worldwide. However, the physiological factors that define Mtb’s pathogenicity are poorly understood. Here, we report the structure and function of a protein that is required for optimal in vitro fitness and bears homology to two distinct enzymes, Rv0812. Despite diversification of related orthologues into biochemically distinct enzyme families, rv0812 encodes a single active site with aminodeoxychorismate lyase and D–amino acid transaminase activities. The mutual exclusivity of substrate occupancy in this active site mediates coupling between nucleic acid and cell wall biosynthesis, prioritizing PABA over D-Ala/D-Glu biosynthesis. This bifunctionality reveals a novel, enzymatically encoded fail-safe mechanism that may help Mtb and other bacteria couple replication and division.
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Affiliation(s)
| | - Lijun Duan
- Texas A&M University, College Station, TX
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4
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Singh R, Slade JA, Brockett M, Mendez D, Liechti GW, Maurelli AT. Competing Substrates for the Bifunctional Diaminopimelic Acid Epimerase/Glutamate Racemase Modulate Peptidoglycan Synthesis in Chlamydia trachomatis. Infect Immun 2020; 89:IAI.00401-20. [PMID: 33106295 PMCID: PMC7927921 DOI: 10.1128/iai.00401-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/21/2020] [Indexed: 11/20/2022] Open
Abstract
The Chlamydia trachomatis genome encodes multiple bifunctional enzymes, such as DapF, which is capable of both diaminopimelic acid (DAP) epimerase and glutamate racemase activity. Our previous work demonstrated the bifunctional activity of chlamydial DapF in vitro and in a heterologous system (Escherichia coli). In the present study, we employed a substrate competition strategy to demonstrate DapF Ct function in vivo in C. trachomatis We reasoned that, because DapF Ct utilizes a shared substrate-binding site for both racemase and epimerase activities, only one activity can occur at a time. Therefore, an excess of one substrate relative to another must determine which activity is favored. We show that the addition of excess l-glutamate or meso-DAP (mDAP) to C. trachomatis resulted in 90% reduction in bacterial titers, compared to untreated controls. Excess l-glutamate reduced in vivo synthesis of mDAP by C. trachomatis to undetectable levels, thus confirming that excess racemase substrate led to inhibition of DapF Ct DAP epimerase activity. We previously showed that expression of dapFCt in a murI (racemase) ΔdapF (epimerase) double mutant of E. coli rescues the d-glutamate auxotrophic defect. Addition of excess mDAP inhibited growth of this strain, but overexpression of dapFCt allowed the mutant to overcome growth inhibition. These results confirm that DapF Ct is the primary target of these mDAP and l-glutamate treatments. Our findings demonstrate that suppression of either the glutamate racemase or epimerase activity of DapF compromises the growth of C. trachomatis Thus, a substrate competition strategy can be a useful tool for in vivo validation of an essential bifunctional enzyme.
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Affiliation(s)
- Raghuveer Singh
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA
| | - Jessica A Slade
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA
| | - Mary Brockett
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Daniel Mendez
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA
| | - George W Liechti
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Anthony T Maurelli
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA
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5
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Sidiq KR, Chow MW, Zhao Z, Daniel RA. Alanine metabolism in Bacillus subtilis. Mol Microbiol 2020; 115:739-757. [PMID: 33155333 DOI: 10.1111/mmi.14640] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/30/2022]
Abstract
Both isomeric forms of alanine play a crucial role in bacterial growth and viability; the L-isomer of this amino acid is one of the building blocks for protein synthesis, and the D-isomer is incorporated into the bacterial cell wall. Despite a long history of genetic manipulation of Bacillus subtilis using auxotrophic markers, the genes involved in alanine metabolism have not been characterized fully. In this work, we genetically characterized the major enzymes involved in B. subtilis alanine biosynthesis and identified an alanine permease, AlaP (YtnA), which we show has a major role in the assimilation of D-alanine from the environment. Our results provide explanations for the puzzling fact that growth of B. subtilis does not result in the significant accumulation of extracellular D-alanine. Interestingly, we find that in B. subtilis, unlike E. coli where multiple enzymes have a biochemical activity that can generate alanine, the primary synthetic enzyme for alanine is encoded by alaT, although a second gene, dat, can support slow growth of an L-alanine auxotroph. However, our results also show that Dat mediates the synthesis of D-alanine and its activity is influenced by the abundance of L-alanine. This work provides valuable insights into alanine metabolism that suggests that the relative abundance of D- and L-alanine might be linked with cytosolic pool of D and L-glutamate, thereby coupling protein and cell envelope synthesis with the metabolic status of the cell. The results also suggest that, although some of the purified enzymes involved in alanine biosynthesis have been shown to catalyze reversible reactions in vitro, most of them function unidirectionally in vivo.
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Affiliation(s)
- Karzan R Sidiq
- Centre for Bacterial Cell Biology, Biosciences Institute, Medical Faculty, Newcastle University, Newcastle Upon Tyne, UK
| | - Man W Chow
- Centre for Bacterial Cell Biology, Biosciences Institute, Medical Faculty, Newcastle University, Newcastle Upon Tyne, UK
| | - Zhao Zhao
- Centre for Bacterial Cell Biology, Biosciences Institute, Medical Faculty, Newcastle University, Newcastle Upon Tyne, UK
| | - Richard A Daniel
- Centre for Bacterial Cell Biology, Biosciences Institute, Medical Faculty, Newcastle University, Newcastle Upon Tyne, UK
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6
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Wang R, Zhang Z, Sun J, Jiao N. Differences in bioavailability of canonical and non-canonical D-amino acids for marine microbes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 733:139216. [PMID: 32454292 DOI: 10.1016/j.scitotenv.2020.139216] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/22/2020] [Accepted: 05/03/2020] [Indexed: 06/11/2023]
Abstract
Dissolved organic matter (DOM) accounts for >95% of total marine organic matter, and >95% of marine DOM is refractory to biodegradation. The recalcitrancy of DOM determines its residence time and thus is of great concern regarding to carbon sequestration in the ocean. However, the recalcitrancy of DOM not only varies among different compounds but also within different conformations of a same molecule such as L-amino acids (L-AAs) and D-amino acids (D-AAs). While the former is labile, the latter is refractory and used as a proxy for estimation of bacterial refractory DOM in the ocean. However, some D-AAs are also reported to be bioavailable. To clarify the controversy, we examined the bioavailability of two types of D-AAs: canonical D-AAs, which mainly present as bacterial cell wall components, and non-canonical D-AAs (NCDAAs), which are secreted by various bacteria as signaling molecules in bacterial physiology. Bioassay experiments were conducted with nine marine bacterial strains and a natural microbial community. D-AAs were poorly utilized by the strains as sole carbon or nitrogen sources compared with L-AAs, in addition, NCDAAs were barely used compared with canonical D-AAs. In comparison, the microbial community consumed all three canonical D-AAs (D-alanine, D-aspartic acid and D-glutamic acid) as efficiently as their corresponding L-AAs when supplied separately; however, L-AAs were preferentially used over D-AAs when both forms were provided simultaneously. Remarkably, two NCDAAs, D-methionine and D-leucine, were poorly utilized regardless of the presence of the L-enantiomers. It was found for the first time that NCDAAs are relatively more refractory than canonical D-AAs to microbial utilization. This novel recognition of difference in recalcitrancy between NCDAAs and canonical D-AAs lays the foundation for a better understanding of carbon cycling and more accurate estimation of carbon storage in the ocean.
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Affiliation(s)
- Rui Wang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, People's Republic of China; Institute of Marine Microbes and Ecospheres, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, People's Republic of China
| | - Zilian Zhang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, People's Republic of China; Institute of Marine Microbes and Ecospheres, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, People's Republic of China.
| | - Jia Sun
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, People's Republic of China; Institute of Marine Microbes and Ecospheres, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, People's Republic of China
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, People's Republic of China; Institute of Marine Microbes and Ecospheres, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, People's Republic of China.
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7
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Maitra A, Munshi T, Healy J, Martin LT, Vollmer W, Keep NH, Bhakta S. Cell wall peptidoglycan in Mycobacterium tuberculosis: An Achilles' heel for the TB-causing pathogen. FEMS Microbiol Rev 2020; 43:548-575. [PMID: 31183501 PMCID: PMC6736417 DOI: 10.1093/femsre/fuz016] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/07/2019] [Indexed: 02/06/2023] Open
Abstract
Tuberculosis (TB), caused by the intracellular pathogen Mycobacterium tuberculosis, remains one of the leading causes of mortality across the world. There is an urgent requirement to build a robust arsenal of effective antimicrobials, targeting novel molecular mechanisms to overcome the challenges posed by the increase of antibiotic resistance in TB. Mycobacterium tuberculosis has a unique cell envelope structure and composition, containing a peptidoglycan layer that is essential for maintaining cellular integrity and for virulence. The enzymes involved in the biosynthesis, degradation, remodelling and recycling of peptidoglycan have resurfaced as attractive targets for anti-infective drug discovery. Here, we review the importance of peptidoglycan, including the structure, function and regulation of key enzymes involved in its metabolism. We also discuss known inhibitors of ATP-dependent Mur ligases, and discuss the potential for the development of pan-enzyme inhibitors targeting multiple Mur ligases.
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Affiliation(s)
- Arundhati Maitra
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Tulika Munshi
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Jess Healy
- Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Liam T Martin
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Nicholas H Keep
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Sanjib Bhakta
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
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8
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Muhammad M, Bai J, Alhassan AJ, Sule H, Ju J, Zhao B, Liu D. Significance of Glutamate Racemase for the Viability and Cell Wall Integrity of Streptococcus iniae. BIOCHEMISTRY (MOSCOW) 2020; 85:248-256. [PMID: 32093601 DOI: 10.1134/s0006297920020121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Streptococcus iniae is a pathogenic and zoonotic bacterium responsible for human diseases and mortality of many fish species. Recently, this bacterium has demonstrated an increasing trend for antibiotics resistance, which has warranted a search for new approaches to tackle its infection. Glutamate racemase (MurI) is a ubiquitous enzyme of the peptidoglycan synthesis pathway that plays an important role in the cell wall integrity maintenance; however, the significance of this enzyme differs in different species. In this study, we knocked out the MurI gene in S. iniae in order to elucidate the role of glutamate racemase in maintaining cell wall integrity in this bacterial species. We also cloned, expressed, and purified MurI and determined its biochemical characteristics. Biochemical analysis revealed that the MurI gene in S. iniae encodes a functional enzyme with a molecular weight of 30 kDa, temperature optimum at 35°C, and pH optimum at 8.5. Metal ions, such as Cu2+, Mn2+, Co2+ and Zn2+, inhibited the enzyme activity. MurI was found to be essential for the viability and cell wall integrity of S. iniae. The optimal growth of the MurI-deficient S. iniae mutant can be achieved only by adding a high concentration of D-glutamate to the medium. Membrane permeability assay of the mutant showed an increasing extent of the cell wall damage with time upon D-glutamate starvation. Moreover, the mutant lost its virulence when incubated in fish blood. Our results demonstrated that the MurI knockout leads to the generation of S. iniae auxotroph with damaged cell walls.
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Affiliation(s)
- M Muhammad
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China.,Kano University of Science and Technology, Department of Biochemistry, Wudil, Nigeria
| | - J Bai
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - A J Alhassan
- Bayero University Kano, Department of Biochemistry, Kano, Nigeria
| | - H Sule
- Bayero University Kano, Department of Medical Laboratory Science, Kano, Nigeria
| | - J Ju
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - B Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China.
| | - D Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China.
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9
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L-Alanine specifically potentiates fluoroquinolone efficacy against Mycobacterium persisters via increased intracellular reactive oxygen species. Appl Microbiol Biotechnol 2020; 104:2137-2147. [PMID: 31940082 DOI: 10.1007/s00253-020-10358-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/23/2019] [Accepted: 01/05/2020] [Indexed: 02/01/2023]
Abstract
Tuberculosis caused by Mycobacterium tuberculosis remains a major global health concern; M. tuberculosis drug resistance and persistence further fueled the situation. Nutrient supportive therapy was intensively pursued to complement the conventional treatment, as well as their synergy with current antibiotics. To explore whether L-alanine can synergize with fluoroquinolones against M. tuberculosis, M. smegmatis was used as a surrogate in this study. We found that L-alanine can boost the bactericidal efficacy of fluoroquinolones, increasing the production of intracellular reactive oxygen species. This effect is very significant for persisters. Accelerated tricarboxylic acid cycle and/or nucleotide metabolism were observed after the addition of L-alanine. M. smegmatis MSMEG2660 is a homolog of the alanine dehydrogenase (Rv2780, MSMEG2659) negative regulator Rv2779c and involved in the L-alanine potentiation of fluoroquinolone via funneling more alanine into tricarboxylic acid. Deletion mutant of the MSMEG2660 (∆Ms2660) became more susceptible, and more readily revived from persistence. We firstly found that L-alanine can synergize with fluoroquinolones against Mycobacterium, especially the persisters via promoting metabolism. This will inspire new avenue to eliminate Mycobacterium persisters.
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10
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Opel-Reading H, Mortuza R, Krause K. Detection of D-glutamate Production from the Dual Function Enzyme, 4-amino-4-deoxychorismate Lyase/D-amino Acid Transaminase, in Mycobacterium smegmatis. Bio Protoc 2019; 9:e3135. [DOI: 10.21769/bioprotoc.3135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 11/27/2018] [Accepted: 12/14/2018] [Indexed: 11/02/2022] Open
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11
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Rakovitsky N, Bar Oz M, Goldberg K, Gibbons S, Zimhony O, Barkan D. The Unexpected Essentiality of glnA2 in Mycobacterium smegmatis Is Salvaged by Overexpression of the Global Nitrogen Regulator glnR, but Not by L-, D- or Iso-Glutamine. Front Microbiol 2018; 9:2143. [PMID: 30271391 PMCID: PMC6142876 DOI: 10.3389/fmicb.2018.02143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/21/2018] [Indexed: 01/14/2023] Open
Abstract
Nitrogen metabolism plays a central role in the physiology of microorganisms, and Glutamine Synthetase (GS) genes are present in virtually all bacteria. In M. tuberculosis, four GS genes are present, but only glnA1 is essential, whereas glnA2 was shown to be non-essential for in-vitro as well as in-vivo growth and pathogenesis, and is postulated to be involved in D-glutamine and iso-glutamine synthesis. Whilst investigating the activity of an antimicrobial compound in M. smegmatis, we found a spontaneous temperature-sensitive mutant in glnA2 (I133F), and used it to investigate the role of glnA2 in M. smegmatis. We deleted the native glnA2 and replaced it with a mutated allele. This re-created the temperature sensitivity—as after 3–4 seemingly normal division cycles, glnA2 became essential for growth. This essentiality could not be salvaged by neither L, D- nor iso-glutamine, suggesting an additional role of glnA2 in M. smegmatis over its role in M. tuberculosis. We also found that overexpression of the global nitrogen regulator glnR enabled bypassing the essentiality of glnA2, allowing the creation of a complete deletion mutant. The discrepancy between the importance of glnA2 in Mtb and M. smegmatis stresses the caution in which results in one are extrapolated to the other.
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Affiliation(s)
- Nadya Rakovitsky
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michal Bar Oz
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Karin Goldberg
- Department of Pharmaceutical Engineering, Azrieli College of Engineering, Jerusalem, Israel
| | - Simon Gibbons
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, London, United Kingdom
| | - Oren Zimhony
- Kaplan Medical Center, Rehovot, Israel.,The Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Daniel Barkan
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Jerusalem, Israel
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12
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Yamada H, Yamaguchi M, Igarashi Y, Chikamatsu K, Aono A, Murase Y, Morishige Y, Takaki A, Chibana H, Mitarai S. Mycolicibacterium smegmatis, Basonym Mycobacterium smegmatis, Expresses Morphological Phenotypes Much More Similar to Escherichia coli Than Mycobacterium tuberculosis in Quantitative Structome Analysis and CryoTEM Examination. Front Microbiol 2018; 9:1992. [PMID: 30258411 PMCID: PMC6145149 DOI: 10.3389/fmicb.2018.01992] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/07/2018] [Indexed: 01/05/2023] Open
Abstract
A series of structome analyses, that is, quantitative and three-dimensional structural analysis of a whole cell at the electron microscopic level, have already been achieved individually in Exophiala dermatitidis, Saccharomyces cerevisiae, Mycobacterium tuberculosis, Myojin spiral bacteria, and Escherichia coli. In these analyses, sample cells were processed through cryo-fixation and rapid freeze-substitution, resulting in the exquisite preservation of ultrastructures on the serial ultrathin sections examined by transmission electron microscopy. In this paper, structome analysis of non pathogenic Mycolicibacterium smegmatis, basonym Mycobacterium smegmatis, was performed. As M. smegmatis has often been used in molecular biological experiments and experimental tuberculosis as a substitute of highly pathogenic M. tuberculosis, it has been a task to compare two species in the same genus, Mycobacterium, by structome analysis. Seven M. smegmatis cells cut into serial ultrathin sections, and, totally, 220 serial ultrathin sections were examined by transmission electron microscopy. Cell profiles were measured, including cell length, diameter of cell and cytoplasm, surface area of outer membrane and plasma membrane, volume of whole cell, periplasm, and cytoplasm, and total ribosome number and density per 0.1 fl cytoplasm. These data are based on direct measurement and enumeration of exquisitely preserved single cell structures in the transmission electron microscopy images, and are not based on the calculation or assumptions from biochemical or molecular biological indirect data. All measurements in M. smegmatis, except cell length, are significantly higher than those of M. tuberculosis. In addition, these data may explain the more rapid growth of M. smegmatis than M. tuberculosis and contribute to the understanding of their structural properties, which are substantially different from M. tuberculosis, relating to the expression of antigenicity, acid-fastness, and the mechanism of drug resistance in relation to the ratio of the targets to the corresponding drugs. In addition, data obtained from cryo-transmission electron microscopy examination were used to support the validity of structome analysis. Finally, our data strongly support the most recent establishment of the novel genus Mycolicibacterium, into which basonym Mycobacterium smegmatis has been classified.
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Affiliation(s)
- Hiroyuki Yamada
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | | | - Yuriko Igarashi
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | - Kinuyo Chikamatsu
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | - Akio Aono
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | - Yoshiro Murase
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | - Yuta Morishige
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | - Akiko Takaki
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
| | - Hiroji Chibana
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Satoshi Mitarai
- Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Japan
- Department of Basic Mycobacteriology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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Mandel MJ. D-fining DarR: a LysR-type transcriptional regulator that responds to D-aspartate. J Bacteriol 2018; 200:e00121-18. [PMID: 29555693 PMCID: PMC6040187 DOI: 10.1128/jb.00121-18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Work from Jones, Stabb, et al. describes a D-aspartate sensing system in Proteobacteria. D-amino acids are critical components of peptidoglycan and other structures. The new study identifies the LysR-type transcriptional regulator, DarR, which activates the aspartate racemase RacD. Overexpression of RacD enables it to synthesize D-glutamate and restore normal peptidoglycan in a Vibrio fischeri murI mutant. This study contributes to emerging roles for D-amino acids and how they are synthesized under distinct conditions.
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Affiliation(s)
- Mark J Mandel
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI USA
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