Poly-?-(D)-glutamic acid capsule interferes with lytic infection of Bacillus anthracis by B. anthracis-specific bacteriophages.
Ontology highlight
ABSTRACT:
SUBMITTER: Negus D
PROVIDER: S-EPMC3553781 | biostudies-literature | 2013 Jan
REPOSITORIES: biostudies-literature
Publications
Poly-γ-(D)-glutamic acid capsule interferes with lytic infection of Bacillus anthracis by B. anthracis-specific bacteriophages.
Negus David D Burton Jane J Sweed Angela A Gryko Romuald R Taylor Peter W PW
Applied and environmental microbiology 20121102 2
The poly-γ-d-glutamic acid capsule of Bacillus anthracis is a barrier to infection by B. anthracis-specific bacteriophages. Capsule expression was found to completely inhibit lytic infection by γ phage, an observation supported by the demonstration that this phage does not elaborate a hydrolase that would facilitate penetration through the protective capsule outer layer. ...[more]
Similar Datasets
Project description:Bacillus anthracis is a pathogenic Gram-positive bacterium that causes a highly lethal infectious disease, anthrax. The poly-γ-d-glutamic acid (PGA) capsule is one of the major virulence factors of B. anthracis, along with exotoxins. PGA enables B. anthracis to escape phagocytosis and immune surveillance. Our previous study showed that PGA activates the human macrophage cell line THP-1 and human dendritic cells, resulting in the production of the proinflammatory cytokine interleukin-1β (IL-1β) (M. H. Cho et al., Infect Immun 78:387-392, 2010, http://dx.doi.org/10.1128/IAI.00956-09). Here, we investigated PGA-induced cytokine responses and related signaling pathways in mouse bone marrow-derived macrophages (BMDMs) using Bacillus licheniformis PGA as a surrogate for B. anthracis PGA. Upon exposure to PGA, BMDMs produced proinflammatory mediators, including tumor necrosis factor alpha (TNF-α), IL-6, IL-12p40, and monocyte chemoattractant protein 1 (MCP-1), in a concentration-dependent manner. PGA stimulated Toll-like receptor 2 (TLR2) but not TLR4 in Chinese hamster ovary cells expressing either TLR2 or TLR4. The ability of PGA to induce TNF-α and IL-6 was retained in TLR4(-/-) but not TLR2(-/-) BMDMs. Blocking experiments with specific neutralizing antibodies for TLR1, TLR6, and CD14 showed that TLR6 and CD14 also were necessary for PGA-induced inflammatory responses. Furthermore, PGA enhanced activation of mitogen-activated protein (MAP) kinases and nuclear factor-kappa B (NF-κB), which are responsible for expression of proinflammatory cytokines. Additionally, PGA-induced TNF-α production was abrogated not only in MyD88(-/-) BMDMs but also in BMDMs pretreated with inhibitors of MAP kinases and NF-κB. These results suggest that immune responses induced by PGA occur via TLR2, TLR6, CD14, and MyD88 through activation of MAP kinase and NF-κB pathways.
| S-EPMC4567625 | biostudies-literature
Project description:Zinc and copper are essential micronutrients that serve as a cofactors for numerous enzymes. However, when present at elevated concentrations, zinc and copper are highly toxic to bacteria. To combat the effects of zinc and copper excess, bacteria have evolved a wide array of defense mechanisms. Here, we show that the Gram-positive soil bacterium, Bacillus subtilis, produces the extracellular polymeric substance, poly-gamma-glutamate (γ-PGA) as a protective mechanism in response to zinc and copper excess. Furthermore, we provide evidence that zinc and copper dependent γ-PGA production is independent of the DegS-DegQ two-component regulatory system and likely occurs at a posttranscriptional level through the small protein, PgsE. These data provide new insight into bacterial metal resistance mechanisms and contribute to our understanding of the regulation of bacterial γ-PGA biosynthesis. IMPORTANCE Zinc and copper are potent antimicrobial compounds. As such, bacteria have evolved a diverse range of tools to prevent metal intoxication. Here, we show that the Gram-positive model organism, Bacillus subtilis, produces poly-gamma-glutamic acid (γ-PGA) as a protective mechanism against zinc and copper intoxication and that zinc and copper dependent γ-PGA production occurs by a yet undefined mechanism independent of known γ-PGA regulation pathways.
| S-EPMC9045300 | biostudies-literature
Project description:Poly-γ-glutamic acid (γ-PGA) is a promising microbial polymer with potential applications in industry, agriculture and medicine. The use of high γ-PGA-producing strains is an effective approach to improve productivity of γ-PGA. In this study, we developed a mutant, F3-178, from Bacillus subtilis GXA-28 using genome shuffling. The morphological characteristics of F3-178 and GXA-28 were not identical. Compared with GXA-28 (18.4 ± 0.8 g l-1 ), the yield of γ-PGA was 1.9-fold higher in F3-178 (34.3 ± 1.2 g l-1 ). Results from batch fermentation in 3.7 l fermenter showed that F3-178 was satisfactory for industrial production of γ-PGA. Metabolic studies suggested that the higher γ-PGA yield in F3-178 could be attributed to increased intracellular flux and uptake of extracellular glutamate. Real-time PCR indicated that mRNA level of pgsB in F3-178 was 18.8-fold higher than in GXA-28, suggesting the higher yield might be related to the overexpression of genes involved in γ-PGA production. This study demonstrated that genome shuffling can be used for rapid improvement of γ-PGA strains, and the possible mechanism for the improved phenotype was also explored at the metabolic and transcriptional levels.
| S-EPMC5072198 | biostudies-literature
Project description:Poly-gamma-glutamic acid (PGA) is a promising bio-based polymer that shares many functions with poly (acrylic acid) and its derivatives. Thus, technologies for efficient production and molecular size control of PGA are required to expand the application of this useful biopolymer. In Bacillus strains, PGA is synthesized by the PgsBCA protein complex, which is encoded by the pgsBCA gene operon, otherwise is known as ywsC and ywtAB operons and/or capBCA operon. Hence, we investigated responsible components of the PgsBCA complex in B. subtilis for over-production of PGA. In particular, we constructed genomic pgsBCA gene-deletion mutants of B. subtilis. And also, we assembled high copy-number plasmids harboring σA-dependent promoter, leading to high-level expression of all combinations of pgsBCA, pgsBC, pgsBA, pgsCA, pgsB, pgsC, and/or pgsA genes. Subsequently, PGA production of the transformed B. subtilis mutant was determined in batch fermentation using medium supplemented with L-glutamate. PGA production by the transformants introduced with pgsBC genes (lacking the genomic pgsBCA genes) was 26.0 ± 3.0 g L-1, and the enantiomeric ratio of D- and L-glutamic acid (D/L-ratio) in the produced PGA was 5/95. In contrast, D/L-ratio of produced PGA by the transformants introduced with pgsBCA genes (control strains) was 75/25. In conclusion, B. subtilis without pgsA gene could over-produce PGA with an L-rich enantiomeric ratio.
| S-EPMC6029982 | biostudies-literature
Project description:Poly-γ-glutamic acid (γ-PGA) is a biocompatible and biodegradable polypeptide with wide-ranging applications in foods, cosmetics, medicine, agriculture and wastewater treatment. Bacillus amyloliquefaciens LL3 can produce γ-PGA from sucrose that can be obtained easily from sugarcane and sugar beet. In our previous work, it was found that low intracellular glutamate concentration was the limiting factor for γ-PGA production by LL3. In this study, the γ-PGA synthesis by strain LL3 was enhanced by chromosomally engineering its glutamate metabolism-relevant networks. First, the downstream metabolic pathways were partly blocked by deleting fadR, lysC, aspB, pckA, proAB, rocG and gudB. The resulting strain NK-A6 synthesized 4.84 g l-1 γ-PGA, with a 31.5% increase compared with strain LL3. Second, a strong promoter PC 2up was inserted into the upstream of icd gene, to generate strain NK-A7, which further led to a 33.5% improvement in the γ-PGA titre, achieving 6.46 g l-1 . The NADPH level was improved by regulating the expression of pgi and gndA. Third, metabolic evolution was carried out to generate strain NK-A9E, which showed a comparable γ-PGA titre with strain NK-A7. Finally, the srf and itu operons were deleted respectively, from the original strains NK-A7 and NK-A9E. The resulting strain NK-A11 exhibited the highest γ-PGA titre (7.53 g l-1 ), with a 2.05-fold improvement compared with LL3. The results demonstrated that the approaches described here efficiently enhanced γ-PGA production in B. amyloliquefaciens fermentation.
| S-EPMC6680638 | biostudies-literature
Project description: Not available
| S-EPMC11017564 | biostudies-literature
Project description:BackgroundPoly γ-glutamic acid (γ-PGA) is a promising biopolymer for various applications. For glutamic acid-independent strains, the titer of γ-PGA is too low to meet the industrial demand. In this study, we isolated a novel γ-PGA-producing strain, Bacillus tequilensis BL01, and multiple genetic engineering strategies were implemented to improve γ-PGA production.ResultsFirst, the one-factor-at-a-time method was used to investigate the influence of carbon and nitrogen sources and temperature on γ-PGA production. The optimal sources of carbon and nitrogen were sucrose and (NH4)2SO4 at 37 °C, respectively. Second, the sucA, gudB, pgdS, and ggt genes were knocked out simultaneously, which increased the titer of γ-PGA by 1.75 times. Then, the titer of γ-PGA increased to 18.0 ± 0.3 g/L by co-overexpression of the citZ and pyk genes in the mutant strain. Furthermore, the γ-PGA titer reached 25.3 ± 0.8 g/L with a productivity of 0.84 g/L/h and a yield of 1.50 g of γ-PGA/g of citric acid in fed-batch fermentation. It should be noted that this study enables the synthesis of low (1.84 × 105 Da) and high (2.06 × 106 Da) molecular weight of γ-PGA by BL01 and the engineering strain.ConclusionThe application of recently published strategies to successfully improve γ-PGA production for the new strain B. tequilensis BL01 is reported. The titer of γ-PGA increased 2.17-fold and 1.32-fold compared with that of the wild type strain in the flask and 5 L fermenter. The strain shows excellent promise as a γ-PGA producer compared with previous studies. Meanwhile, different molecular weights of γ-PGA were obtained, enhancing the scope of application in industry.
| S-EPMC9798646 | biostudies-literature
Project description:The main forms of poly-γ-glutamic acid (γ-PGA) applied in agriculture include agricultural γ-PGA and γ-PGA super absorbent polymer (SAP). Laboratory experiments were conducted with a check treatment CK (no γ-PGA added) and two different forms of γ-PGA added to sandy loam soil (T and TM stand for γ-PGA and γ-PGA SAP) at four different soil mass ratios (0.05% (1), 0.10% (2), 0.15% (3) and 0.20% (4)) to determine their effects on sandy loam soil hydro-physical properties. Both of them could reduce the cumulative infiltration of soil water. The total available water (TAW) which the soil water content (SWC) from field water capacity (FC) to permanent wilting point (PWP) after γ-PGA added into sandy loam soil had no significant different compared with CK, and the TAW was highest at the treatment of γ-PGA with 0.10% addition amount into sandy loam soil. However, the TAW of sandy loam soil increased dramatically with the γ-PGA SAP addition amount increasing. TM3 had the highest soil water absorption among the treatments with γ-PGA SAP. The T1 to T4 treatments with γ-PGA addition slightly prolonged retention time (RT) when SWC varied from FC to PWP compared with CK. For γ-PGA SAP addition treatments, the time for SWC varied from FC to PWP was 1.48 times (TM1), 1.88 times (TM2), 2.01 times (TM3) and 2.87 times (TM4) longer than that of CK, respectively. The results of this study will provide further information for the use of these materials in agricultural application.
| S-EPMC7983855 | biostudies-literature
Project description:Bacillus paralicheniformis bcasdu2018/01 was isolated from the indoor environment of a chemistry laboratory. As part of the extracellular matrix, this isolate produces copious amounts of poly-γ-glutamic acid (γ-PGA). Here, we report the 4.25-Mbp draft genome assembly of the organism with an average G+C content of 45.92%.
| S-EPMC8601133 | biostudies-literature
Project description:Bacillus anthracis poly-?-D-glutamic acid (PGA) capsule is an essential virulent factor that helps the bacterial pathogen to escape host immunity. Like other encapsulated bacterial species, the B. anthracis capsule may also inhibit complement-mediated clearance and ensure bacterial survival in the host. Previous reports suggest that B. anthracis spore proteins inhibit complement activation. However, the mechanism through which the B. anthracis capsule imparts a survival advantage to the active bacteria has not been demonstrated till date. Thus, to evaluate the role of the PGA capsule in evading host immunity, we have undertaken the present head-to-head comparative study of the phagocytosis and complement activation of non-encapsulated and encapsulated B. anthracis strains. The encapsulated virulent strain exhibited resistance toward complement-dependent and complement-independent bacterial phagocytosis by human macrophages. The non-encapsulated Sterne strain was highly susceptible to phagocytosis by THP-1 macrophages, after incubation with normal human serum (NHS), heat-inactivated serum, and serum-free media, thus indicating that the capsule inhibited both complement-dependent and complement-independent opsonic phagocytosis. An increased binding of C3b and its subsequent activation to C3c and C3dg, which functionally act as potent opsonins, were observed with the non-encapsulated Sterne strain compared with the encapsulated strain. Other known mediators of complement fixation, IgG, C-reactive protein (CRP), and serum amyloid P component (SAP), also bound more prominently with the non-encapsulated Sterne strain. Studies with complement pathway-specific, component-deficient serum demonstrated that the classical pathway was primarily involved in mediating C3b binding on the non-encapsulated bacteria. Both strains equally bound the complement regulatory proteins C4BP and factor H. Importantly, we demonstrated that the negative charge of the PGA capsule was responsible for the differential binding of the complement proteins between the non-encapsulated and encapsulated strains. At lower pH closer to the isoelectric point of PGA, the neutralization of the negative charge was associated with an increased binding of C3b and IgG with the encapsulated B. anthracis strain. Overall, our data have demonstrated that the B. anthracis capsule inhibits complement fixation and opsonization resulting in reduced phagocytosis by macrophages, thus allowing the bacterial pathogen to evade host immunity.
| S-EPMC7138205 | biostudies-literature