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Hao M, Wang M, Tang T, Zhao D, Yin S, Shi Y, Liu X, Wudong G, Yang Y, Zhang M, Qi L, Zhou D, Liu W, Jin Y, Wang A. Regulation of the Gene for Alanine Racemase Modulates Amino Acid Metabolism with Consequent Alterations in Cell Wall Properties and Adhesive Capability in Brucella spp. Int J Mol Sci 2023; 24:16145. [PMID: 38003334 PMCID: PMC10671322 DOI: 10.3390/ijms242216145] [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: 09/09/2023] [Revised: 10/24/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
Brucella, a zoonotic facultative intracellular pathogenic bacterium, poses a significant threat both to human health and to the development of the livestock industry. Alanine racemase (Alr), the enzyme responsible for alanine racemization, plays a pivotal role in regulating virulence in this bacterium. Moreover, Brucella mutants with alr gene deletions (Δalr) exhibit potential as vaccine candidates. However, the mechanisms that underlie the detrimental effects of alr knockouts on Brucella pathogenicity remain elusive. Here, initially, we conducted a bioinformatics analysis of Alr, which demonstrated a high degree of conservation of the protein within Brucella spp. Subsequent metabolomics studies unveiled alterations in amino acid pathways following deletion of the alr gene. Furthermore, alr deletion in Brucella suis S2 induced decreased resistance to stress, antibiotics, and other factors. Transmission electron microscopy of simulated macrophage intracellular infection revealed damage to the cell wall in the Δalr strain, whereas propidium iodide staining and alkaline phosphatase and lactate dehydrogenase assays demonstrated alterations in cell membrane permeability. Changes in cell wall properties were revealed by measurements of cell surface hydrophobicity and zeta potential. Finally, the diminished adhesion capacity of the Δalr strain was shown by immunofluorescence and bacterial enumeration assays. In summary, our findings indicate that the alr gene that regulates amino acid metabolism in Brucella influences the properties of the cell wall, which modulates bacterial adherence capability. This study is the first demonstration that Alr impacts virulence by modulating bacterial metabolism, thereby providing novel insights into the pathogenic mechanisms of Brucella spp.
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Affiliation(s)
- Mingyue Hao
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Minghui Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Ting Tang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Danyu Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Shurong Yin
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Yong Shi
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Xiaofang Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Gaowa Wudong
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Yuanhao Yang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Mengyu Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Lin Qi
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Dong Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Wei Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Yaping Jin
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Aihua Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China; (M.H.); (M.W.); (T.T.); (D.Z.); (S.Y.); (Y.S.); (X.L.); (G.W.); (Y.Y.); (M.Z.); (L.Q.); (D.Z.); (W.L.); (Y.J.)
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
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Li F, Mei Z, Ju N, Sui L, Fan X, Wang Z, Li J, Jiang Y, Cui W, Shan Z, Zhou H, Wang L, Qiao X, Tang L, Wang X, Li Y. Evaluation of the immunogenicity of auxotrophic Lactobacillus with CRISPR-Cas9D10A system-mediated chromosomal editing to express porcine rotavirus capsid protein VP4. Virulence 2022; 13:1315-1330. [PMID: 35920261 PMCID: PMC9351582 DOI: 10.1080/21505594.2022.2107646] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 07/13/2022] [Accepted: 07/26/2022] [Indexed: 11/06/2022] Open
Abstract
Porcine rotavirus (PoRV) is an important pathogen, leading to the occurrence of viral diarrhoea . As the infection displays obvious enterotropism, intestinal mucosal immunity is the significant line of defence against pathogen invasion. Moreover, as lactic acid bacteria (LAB) show acid resistance, bile salt resistance and immune regulation, it is of great significance to develop an oral vaccine. Most traditional plasmid delivery vectors use antibiotic genes as selective markers, easily leading to antibiotic accumulation. Therefore, to select a food-grade marker in genetically engineering food-grade microorganisms is vital. Based on the CRISPR-Cas9D10A system, we constructed a stable auxotrophic Lactobacillus paracasei HLJ-27 (Lactobacillus △Alr HLJ-27) strain. In addition, as many plasmids replicate in the host bacteria, resulting in internal gene deletions. In this study,we used a temperature-sensitive gene editing plasmidto insert the VP4 gene into the genome, yielding the insertion mutant strains VP4/△Alr HLJ-27, VP4/△Alr W56, and VP4/W56. This recombinant bacterium efficiently induced secretory immunoglobulin A (SIgA)-based mucosal and immunoglobulin G (IgG)-based humoral immune responses. These oral mucosal vaccines have the potential to act as an alternative to the application of antibiotics in the future and induce efficient immune responses against PEDV infection.
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Affiliation(s)
- Fengsai Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Zhuyuan Mei
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Ning Ju
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Ling Sui
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Xiaolong Fan
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Zi Wang
- Tongliao Institute of agriculture and animal husbandry, Tongliao City, China
| | - Jiaxuan Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Yanping Jiang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Wen Cui
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Zhifu Shan
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin, Heilongjiang, China
| | - Han Zhou
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Li Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin, Heilongjiang, China
| | - Xinyuan Qiao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin, Heilongjiang, China
| | - Lijie Tang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin, Heilongjiang, China
| | - Xiaona Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin, Heilongjiang, China
| | - Yijing Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin, Heilongjiang, China
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Liu D, Zhang T, Wang Y, Muhammad M, Xue W, Ju J, Zhao B. Knockout of alanine racemase gene attenuates the pathogenicity of Aeromonas hydrophila. BMC Microbiol 2019; 19:72. [PMID: 30940083 PMCID: PMC6444436 DOI: 10.1186/s12866-019-1437-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/17/2019] [Indexed: 11/10/2022] Open
Abstract
Background Aeromonas hydrophila is an opportunistic pathogen of poikilothermic and homoeothermic animals, including humans. In the present study, we described the role of Alanine racemase (alr-2) in the virulence of A. hydrophila using an alr-2 knockout mutant (A.H.Δalr). Results In mouse and common carp models, the survival of animals challenged with A.H.Δalr was significantly increased compared with the wild-type (WT), and the mutant was also impaired in its ability to replicate in the organs and blood of infected mice and fish. The A.H.Δalr significantly increased phagocytosis by macrophages of the mice and fish. These attenuation effects of alr-2 could be complemented by the addition of D-alanine to the A.H.Δalr strain. The histopathology results indicated that the extent of tissue injury in the WT-infected animals was more severe than in the A.H.Δalr-infected groups. The expression of 9 virulence genes was significantly down-regulated, and 3 outer membrane genes were significantly up-regulated in A.H.Δalr. Conclusions Our data suggest that alr-2 is essential for the virulence of A. hydrophila. Our findings suggested alanine racemase could be applied in the development of new antibiotics against A. hydrophila.
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Affiliation(s)
- Dong Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Ting Zhang
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yaping Wang
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Murtala Muhammad
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Wen Xue
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jiansong Ju
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Baohua Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China.
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Paul E, Albert A, Ponnusamy S, Mishra SR, Vignesh AG, Sivakumar SM, Sivasamy G, Sadasivam SG. Designer probiotic Lactobacillus plantarum expressing oxalate decarboxylase developed using group II intron degrades intestinal oxalate in hyperoxaluric rats. Microbiol Res 2018; 215:65-75. [DOI: 10.1016/j.micres.2018.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 03/28/2018] [Accepted: 06/17/2018] [Indexed: 12/22/2022]
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Moscoso M, García P, Cabral MP, Rumbo C, Bou G. A D-Alanine auxotrophic live vaccine is effective against lethal infection caused by Staphylococcus aureus. Virulence 2018; 9:604-620. [PMID: 29297750 PMCID: PMC5955480 DOI: 10.1080/21505594.2017.1417723] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus infections are becoming a major global health issue due to the rapid emergence of multidrug-resistant strains. Therefore, there is an urgent need to develop an effective vaccine to prevent and control these infections. In order to develop a universal immunization strategy, we constructed a mutant derivative of S. aureus 132 which lacks the genes involved in D-alanine biosynthesis, a structural component of cell wall peptidoglycan. This unmarked deletion mutant requires the exogenous addition of D-alanine for in vitro growth. The aim of this study was to examine the ability of this D-alanine auxotroph to induce protective immunity against staphylococcal infection. Our findings demonstrate that this deletion mutant is highly attenuated, elicits a protective immune response in mice and generates cross-reactive antibodies. Moreover, the D-alanine auxotroph was completely eliminated from the blood of mice after its intravenous or intraperitoneal injection. We determined that the protective effect was dependent on antibody production since the adoptive transfer of immune serum into naïve mice resulted in effective protection against S. aureus bacteremia. In addition, splenocytes from mice immunized with the D-alanine auxotroph vaccine showed specific production of IL-17A after ex vivo stimulation. We conclude that this D-alanine auxotroph protects mice efficiently against virulent staphylococcal strains through the combined action of antibodies and IL-17A, and therefore constitutes a promising vaccine candidate against staphylococcal disease, for which no licensed vaccine is available yet.
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Affiliation(s)
- Miriam Moscoso
- a Department of Microbiology , University Hospital A Coruña (CHUAC) - Biomedical Research Institute A Coruña (INIBIC) , A Coruña , Spain
| | - Patricia García
- a Department of Microbiology , University Hospital A Coruña (CHUAC) - Biomedical Research Institute A Coruña (INIBIC) , A Coruña , Spain
| | - Maria P Cabral
- a Department of Microbiology , University Hospital A Coruña (CHUAC) - Biomedical Research Institute A Coruña (INIBIC) , A Coruña , Spain
| | - Carlos Rumbo
- a Department of Microbiology , University Hospital A Coruña (CHUAC) - Biomedical Research Institute A Coruña (INIBIC) , A Coruña , Spain.,b International Research Center in Critical Raw Materials-ICCRAM, University of Burgos , Burgos , Spain.,c Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y León. Spain. University of Burgos. Hospital del Rey s/n , Burgos , Spain
| | - Germán Bou
- a Department of Microbiology , University Hospital A Coruña (CHUAC) - Biomedical Research Institute A Coruña (INIBIC) , A Coruña , Spain
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Ray S, Das S, Panda PK, Suar M. Identification of a new alanine racemase in Salmonella Enteritidis and its contribution to pathogenesis. Gut Pathog 2018; 10:30. [PMID: 30008809 PMCID: PMC6040060 DOI: 10.1186/s13099-018-0257-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/03/2018] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Non-typhoidal Salmonella (NTS) infections caused primarily by S. Enteritidis and S. Typhimurium particularly in immunocompromised hosts have accounted for a large percentage of fatalities in developed nations. Antibiotics have revolutionized the cure of enteric infections but have also led to the rapid emergence of pathogen resistance. New powerful therapeutics involving metabolic enzymes are expected to be potential targets for combating microbial infections and ensuring effective health management. Therefore, the need for new antimicrobials to fight such health emergencies is paramount. Enteric bacteria successfully evade the gut and colonize their hosts through specialized virulence strategies. An important player, alanine racemase is a key enzyme facilitating bacterial survival. RESULTS This study aims at understanding the contribution of alanine racemase genes alr, dadX and SEN3897 to Salmonella survival in vitro and in vivo. We have shown SEN3897 to function as a unique alanine racemase in S. Enteritidis which displayed essential alanine racemase activity. Interestingly, the sole presence of this gene in alr dadX double mutant showed a strict dependence on d-alanine supplementation both in vitro and in vivo. However, Alr complementation in d-alanine auxotrophic strain restored the alanine racemase deficiency. The Km and Vmax of SEN3897 was 89.15 ± 10.2 mM, 400 ± 25.6 µmol/(min mg) for l-alanine and 35 ± 6 mM, 132.5 ± 11.3 µmol/(min mg) for d-alanine, respectively. In vitro assays for invasion and survival as well as in vivo virulence assays involving SEN3897 mutant showed attenuated phenotypes. Further, this study also showed attenuation of d-alanine auxotrophic strain in vivo for the development of potential targets against Salmonella that can be investigated further. CONCLUSION This study identified a third alanine racemase gene unique in S. Enteritidis which had a potential effect on survival and pathogenesis in vitro and in vivo. Our results also confirmed that SEN3897 by itself wasn't able to rescue d-alanine auxotrophy in S. Enteritidis which further contributed to its virulence properties.
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Affiliation(s)
- Shilpa Ray
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha India
| | - Susmita Das
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha India
| | | | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha India
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Wei Y, Qiu W, Zhou XD, Zheng X, Zhang KK, Wang SD, Li YQ, Cheng L, Li JY, Xu X, Li MY. Alanine racemase is essential for the growth and interspecies competitiveness of Streptococcus mutans. Int J Oral Sci 2016; 8:231-238. [PMID: 27740612 PMCID: PMC5168415 DOI: 10.1038/ijos.2016.34] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2016] [Indexed: 02/05/2023] Open
Abstract
D-alanine (D-Ala) is an essential amino acid that has a key role in bacterial cell wall synthesis. Alanine racemase (Alr) is a unique enzyme that interconverts L-alanine and D-alanine in most bacteria, making this enzyme a potential target for antimicrobial drug development. Streptococcus mutans is a major causative factor of dental caries. The factors involved in the survival, virulence and interspecies interactions of S. mutans could be exploited as potential targets for caries control. The current study aimed to investigate the physiological role of Alr in S. mutans. We constructed alr mutant strain of S. mutans and evaluated its phenotypic traits and interspecies competitiveness compared with the wild-type strain. We found that alr deletion was lethal to S. mutans. A minimal supplement of D-Ala (150 μg·mL-1) was required for the optimal growth of the alr mutant. The depletion of D-alanine in the growth medium resulted in cell wall perforation and cell lysis in the alr mutant strain. We also determined the compromised competitiveness of the alr mutant strain relative to the wild-type S. mutans against other oral streptococci (S. sanguinis or S. gordonii), demonstrated using either conditioned medium assays or dual-species fluorescent in situ hybridization analysis. Given the importance and necessity of alr to the growth and competitiveness of S. mutans, Alr may represent a promising target to modulate the cariogenicity of oral biofilms and to benefit the management of dental caries.
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Affiliation(s)
- Yuan Wei
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Wei Qiu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xue-Dong Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Zheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ke-Ke Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Shi-Da Wang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yu-Qing Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lei Cheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ji-Yao Li
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ming-Yun Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Complementation of Arginine Auxotrophy for Genetic Transformation of Coxiella burnetii by Use of a Defined Axenic Medium. Appl Environ Microbiol 2016; 82:3042-51. [PMID: 26969695 DOI: 10.1128/aem.00261-16] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/08/2016] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Host cell-free (axenic) culture of Coxiella burnetii in acidified citrate cysteine medium-2 (ACCM-2) has provided important opportunities for investigating the biology of this naturally obligate intracellular pathogen and enabled the development of tools for genetic manipulation. However, ACCM-2 has complex nutrient sources that preclude a detailed study of nutritional factors required for C. burnetii growth. Metabolic reconstruction of C. burnetii predicts that the bacterium cannot synthesize all amino acids and therefore must sequester some from the host. To examine C. burnetii amino acid auxotrophies, we developed a nutritionally defined medium with known amino acid concentrations, termed ACCM-D. Compared to ACCM-2, ACCM-D supported longer logarithmic growth, a more gradual transition to stationary phase, and approximately 5- to 10-fold greater overall replication. Small-cell-variant morphological forms generated in ACCM-D also showed increased viability relative to that generated in ACCM-2. Lack of growth in amino acid-deficient formulations of ACCM-D revealed C. burnetii auxotrophy for 11 amino acids, including arginine. Heterologous expression of Legionella pneumophila argGH in C. burnetii permitted growth in ACCM-D missing arginine and supplemented with citrulline, thereby providing a nonantibiotic means of selection of C. burnetii genetic transformants. Consistent with bioinformatic predictions, the elimination of glucose did not impair C. burnetii replication. Together, these results highlight the advantages of a nutritionally defined medium in investigations of C. burnetii metabolism and the development of genetic tools. IMPORTANCE Host cell-free growth and genetic manipulation of Coxiella burnetii have revolutionized research of this intracellular bacterial pathogen. Nonetheless, undefined components of growth medium have made studies of C. burnetii physiology difficult and have precluded the development of selectable markers for genetic transformation based on nutritional deficiencies. Here, we describe a medium, containing only amino acids as the sole source of carbon and energy, which supports robust growth and improved viability of C. burnetii Growth studies confirmed that C. burnetii cannot replicate in medium lacking arginine. However, genetic transformation of the bacterium with constructs containing the last two genes in the L. pneumophila arginine biosynthesis pathway (argGH) allowed growth on defined medium missing arginine but supplemented with the arginine precursor citrulline. Our results advance the field by facilitating studies of C. burnetii metabolism and allowing non-antibiotic-based selection of C. burnetii genetic transformants, an important achievement considering that selectable makers based on antibiotic resistance are limited.
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Liu D, Zhang L, Xue W, Wang Y, Ju J, Zhao B. Knockout of the alanine racemase gene inAeromonas hydrophilaHBNUAh01 results in cell wall damage and enhanced membrane permeability. FEMS Microbiol Lett 2015; 362:fnv089. [DOI: 10.1093/femsle/fnv089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2015] [Indexed: 11/14/2022] Open
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Liu D, Liu X, Zhang L, Jiao H, Ju J, Zhao B. Biochemical characteristics of an alanine racemase from Aeromonas hydrophil HBNUAh01. Microbiology (Reading) 2015. [DOI: 10.1134/s0026261715020071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Fu R, Liu L, Guo Y, Guo L, Yang L. Sequential micellar electrokinetic chromatography analysis of racemization reaction of alanine enantiomers. J Chromatogr A 2014; 1331:123-8. [DOI: 10.1016/j.chroma.2014.01.058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 01/16/2014] [Accepted: 01/19/2014] [Indexed: 12/13/2022]
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Purification and structural characterization of siderophore (corynebactin) from Corynebacterium diphtheriae. PLoS One 2012; 7:e34591. [PMID: 22514641 PMCID: PMC3326035 DOI: 10.1371/journal.pone.0034591] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 03/02/2012] [Indexed: 12/31/2022] Open
Abstract
During infection, Corynebacterium diphtheriae must compete with host iron-sequestering mechanisms for iron. C. diphtheriae can acquire iron by a siderophore-dependent iron-uptake pathway, by uptake and degradation of heme, or both. Previous studies showed that production of siderophore (corynebactin) by C. diphtheriae is repressed under high-iron growth conditions by the iron-activated diphtheria toxin repressor (DtxR) and that partially purified corynebactin fails to react in chemical assays for catecholate or hydroxamate compounds. In this study, we purified corynebactin from supernatants of low-iron cultures of the siderophore-overproducing, DtxR-negative mutant strain C. diphtheriae C7(β) ΔdtxR by sequential anion-exchange chromatography on AG1-X2 and Source 15Q resins, followed by reverse-phase high-performance liquid chromatography (RP-HPLC) on Zorbax C8 resin. The Chrome Azurol S (CAS) chemical assay for siderophores was used to detect and measure corynebactin during purification, and the biological activity of purified corynebactin was shown by its ability to promote growth and iron uptake in siderophore-deficient mutant strains of C. diphtheriae under iron-limiting conditions. Mass spectrometry and NMR analysis demonstrated that corynebactin has a novel structure, consisting of a central lysine residue linked through its α- and ε- amino groups by amide bonds to the terminal carboxyl groups of two different citrate residues. Corynebactin from C. diphtheriae is structurally related to staphyloferrin A from Staphylococcus aureus and rhizoferrin from Rhizopus microsporus in which d-ornithine or 1,4-diaminobutane, respectively, replaces the central lysine residue that is present in corynebactin.
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