scholarly journals Roles of Germination-Specific Lytic Enzymes CwlJ and SleB in Bacillus anthracis

2009 ◽  
Vol 191 (7) ◽  
pp. 2237-2247 ◽  
Author(s):  
Jared D. Heffron ◽  
Benjamin Orsburn ◽  
David L. Popham
Keyword(s):  
Bacillus Anthracis ◽  
High Performance ◽  
Structural Characteristics ◽  
Wild Type ◽  
Lytic Enzymes ◽  
Spectroscopy Analysis ◽  
Lytic Transglycosylase ◽  
Spore Resistance ◽  
Sequence Similarities ◽  
Mass Spectroscopy Analysis

ABSTRACT The structural characteristics of a spore enable it to withstand stresses that typically kill a vegetative cell. Spores remain dormant until small molecule signals induce them to germinate into vegetative bacilli. Germination requires degradation of the thick cortical peptidoglycan by germination-specific lytic enzymes (GSLEs). Bacillus anthracis has four putative GSLEs, based upon sequence similarities with enzymes in other species: SleB, CwlJ1, CwlJ2, and SleL. In this study, the roles of SleB, CwlJ1, and CwlJ2 were examined. The expression levels of all three genes peak 3.5 h into sporulation. Genetic analysis revealed that, similar to other known GSLEs, none of these gene products are individually required for growth, sporulation, or triggering of germination. However, later germination events are affected in spores lacking CwlJ1 or SleB. Compared to the wild type, germinating spores without CwlJ1 suffer a delay in optical density loss and cortex peptidoglycan release. The absence of SleB also causes a delay in cortex fragment release. A double mutant lacking both SleB and CwlJ1 is completely blocked in cortex hydrolysis and progresses through outgrowth to produce colonies at a frequency 1,000-fold lower than that of the wild-type strain. A null mutation eliminating CwlJ2 has no effect on germination. High-performance liquid chromatography and mass spectroscopy analysis revealed that SleB is required for lytic transglycosylase activity. CwlJ1 also clearly participates in cortex hydrolysis, but its specific mode of action remains unclear. Understanding the lytic germination activities that naturally diminish spore resistance can lead to methods for prematurely inducing them, thus simplifying the process of treating contaminated sites.

scholarly journals The ExsY Protein Is Required for Complete Formation of the Exosporium of Bacillus anthracis

2006 ◽  
Vol 188 (21) ◽  
pp. 7440-7448 ◽  
Author(s):  
Jeremy A. Boydston ◽  
Ling Yue ◽  
John F. Kearney ◽  
Charles L. Turnbough
Keyword(s):  
Bacillus Anthracis ◽  
Solid Medium ◽  
Basal Layer ◽  
Wild Type ◽  
Nucleoside Hydrolase ◽  
Spore Resistance ◽  
Normal Hair ◽  
Spore Outgrowth ◽  
Microscopic Inspection ◽  
Complete Formation

ABSTRACT The outermost layer of the Bacillus anthracis spore is the exosporium, which is composed of a paracrystalline basal layer and an external hair-like nap. The filaments of the nap are formed by a collagen-like glycoprotein called BclA, while the basal layer contains several different proteins. One of the putative basal layer proteins is ExsY. In this study, we constructed a ΔexsY mutant of B. anthracis, which is devoid of ExsY, and examined the assembly of the exosporium on spores produced by this strain. Our results show that exosporium assembly on ΔexsY spores is aberrant, with assembly arrested after the formation of a cap-like fragment that covers one end of the forespore—always the end near the middle of the mother cell. The cap contains a normal hair-like nap but an irregular basal layer. The cap is retained on spores prepared on solid medium, even after spore purification, but it is lost from spores prepared in liquid medium. Microscopic inspection of ΔexsY spores prepared on solid medium revealed a fragile sac-like sublayer of the exosporium basal layer, to which caps were attached. Examination of purified ΔexsY spores devoid of exosporium showed that they lacked detectable levels of BclA and the basal layer proteins BxpB, BxpC, CotY, and inosine-uridine-preferring nucleoside hydrolase; however, these spores retained half the amount of alanine racemase presumed to be associated with the exosporium of wild-type spores. The ΔexsY mutation did not affect spore production and germination efficiencies or spore resistance but did influence the course of spore outgrowth.

scholarly journals The Bacillus anthracis SleL (YaaH) Protein Is an N-Acetylglucosaminidase Involved in Spore Cortex Depolymerization

2008 ◽  
Vol 190 (23) ◽  
pp. 7601-7607 ◽  
Author(s):  
Emily A. Lambert ◽  
David L. Popham
Keyword(s):  
Bacillus Anthracis ◽  
Dipicolinic Acid ◽  
Diaminopimelic Acid ◽  
Lytic Enzyme ◽  
Wild Type ◽  
Lytic Enzymes ◽  
Spore Viability ◽  
Chromatography Analysis ◽  
Protective Layers ◽  
Acid Release

ABSTRACT Bacillus anthracis spores, the infectious agents of anthrax, are notoriously difficult to remove from contaminated areas because they are resistant to many eradication methods. These resistance properties are due to the spore's dehydration and dormancy and to the multiple protective layers surrounding the spore core, one of which is the cortex. In order for B. anthracis spores to germinate and resume growth, the cortex peptidoglycan must be depolymerized. This study reports on analyses of sleL (yaaH), which encodes a cortex-lytic enzyme. The inactivation of sleL does not affect vegetative growth, spore viability, or the initial stages of germination, including dipicolinic acid release. However, mutant spores exhibit a slight delay in the loss of optical density compared to that of wild-type spores. Mutants also retain more diaminopimelic acid and N-acetylmuramic acid during germination than wild-type spores, suggesting that the cortex peptidoglycan is not being hydrolyzed as rapidly. This finding is supported by high-pressure liquid chromatography analysis of the peptidoglycan structure used to confirm that SleL acts as an N-acetylglucosaminidase. When sleL is inactivated, the cortex peptidoglycan is not depolymerized into small muropeptides but instead is retained within the spore as large fragments. In the absence of the sleL-encoded N-acetylglucosaminidase, other cortex-lytic enzymes break down the cortex peptidoglycan sufficiently to allow rapid germination and outgrowth.

scholarly journals Isolation of a Bacterial Strain Able To Degrade Branched Nonylphenol

1999 ◽  
Vol 65 (2) ◽  
pp. 746-751 ◽  
Author(s):  
Tom Tanghe ◽  
Willem Dhooge ◽  
Willy Verstraete
Keyword(s):  
High Performance ◽  
Liquid Culture ◽  
Culture Media ◽  
Spectroscopy Analysis ◽  
Prolonged Incubation ◽  
Intermediary Product ◽  
Special Approach ◽  
Gas Chromatography Mass Spectroscopy ◽  
Phenol Ring ◽  
Mass Spectroscopy Analysis

ABSTRACT Conventional enrichment of microorganisms on branched nonylphenol (NP) as only carbon and energy source yielded mixed cultures able to grow on the organic compound. However, plating yielded no single colonies capable, alone or in combination with other isolates, of degrading the NP in liquid culture. Therefore, a special approach was used, referred to as “serial dilution-plate resuspension,” to reduce culture complexity. In this way, one isolate, TTNP3, tentatively identified as a Sphingomonas sp., was found to be able to grow on NP in liquid culture. Remarkably, this isolate was able to be filtered through a 0.45-μm-pore-diameter filter. Moreover, isolate TTNP3 did not form visible colonies on mineral medium with NP, and it formed visible colonies on R2A agar only after a prolonged incubation of 1 week. High-performance liquid chromatography and gas chromatography-mass spectroscopy analysis of the culture media indicated that the strain starts the degradation of NP with a fission of the phenol ring and preferably uses the para isomer of NP and not the ortho isomer. No distinct accumulation of an intermediary product could be observed.

scholarly journals The Germination-Specific Lytic Enzymes SleB, CwlJ1, and CwlJ2 Each Contribute to Bacillus anthracis Spore Germination and Virulence

2009 ◽  
Vol 191 (18) ◽  
pp. 5569-5576 ◽  
Author(s):  
Jonathan D. Giebel ◽  
Katherine A. Carr ◽  
Erica C. Anderson ◽  
Philip C. Hanna
Keyword(s):  
Bacillus Anthracis ◽  
Spore Germination ◽  
Small Subset ◽  
Wild Type ◽  
Lytic Enzymes ◽  
Phenotypic Analysis ◽  
Rich Media ◽  
Order Of Magnitude ◽  
Forming Efficiency

ABSTRACT The bacterial spore cortex is critical for spore stability and dormancy and must be hydrolyzed by germination-specific lytic enzymes (GSLEs), which allows complete germination and vegetative cell outgrowth. We created in-frame deletions of three genes that encode GSLEs that have been shown to be active in Bacillus anthracis germination: sleB, cwlJ1, and cwlJ2. Phenotypic analysis of individual null mutations showed that the removal of any one of these genes was not sufficient to disrupt spore germination in nutrient-rich media. This finding indicates that these genes have partially redundant functions. Double and triple deletions of these genes resulted in more significant defects. Although a small subset of ΔsleB ΔcwlJ1 spores germinate with wild-type kinetics, for the overall population there is a 3-order-of-magnitude decrease in the colony-forming efficiency compared with wild-type spores. ΔsleB ΔcwlJ1 ΔcwlJ2 spores are unable to complete germination in nutrient-rich conditions in vitro. Both ΔsleB ΔcwlJ1 and ΔsleB ΔcwlJ1 ΔcwlJ2 spores are significantly attenuated, but are not completely devoid of virulence, in a mouse model of inhalation anthrax. Although unable to germinate in standard nutrient-rich media, spores lacking SleB, CwlJ1, and CwlJ2 are able to germinate in whole blood and serum in vitro, which may explain the persistent low levels of virulence observed in mouse infections. This work contributes to our understanding of GSLE activation and function during germination. This information may result in identification of useful therapeutic targets for the disease anthrax, as well as provide insights into ways to induce the breakdown of the protective cortex layer, facilitating easier decontamination of resistant spores.

scholarly journals Contributions of Four Cortex Lytic Enzymes to Germination of Bacillus anthracis Spores

2009 ◽  
Vol 192 (3) ◽  
pp. 763-770 ◽  
Author(s):  
Jared D. Heffron ◽  
Emily A. Lambert ◽  
Nora Sherry ◽  
David L. Popham
Keyword(s):  
Bacillus Anthracis ◽  
Dipicolinic Acid ◽  
Lytic Enzymes ◽  
Spore Viability ◽  
Cooperative Action ◽  
Lytic Transglycosylase ◽  
Mutant Strains ◽  
Bacillus Anthracis Spores ◽  
Quantitative Identification

ABSTRACT Bacterial spores remain dormant and highly resistant to environmental stress until they germinate. Completion of germination requires the degradation of spore cortex peptidoglycan by germination-specific lytic enzymes (GSLEs). Bacillus anthracis has four GSLEs: CwlJ1, CwlJ2, SleB, and SleL. In this study, the cooperative action of all four GSLEs in vivo was investigated by combining in-frame deletion mutations to generate all possible double, triple, and quadruple GSLE mutant strains. Analyses of mutant strains during spore germination and outgrowth combined observations of optical density loss, colony-producing ability, and quantitative identification of spore cortex fragments. The lytic transglycosylase SleB alone can facilitate enough digestion to allow full spore viability and generates a variety of small and large cortex fragments. CwlJ1 is also sufficient to allow completion of nutrient-triggered germination independently and is a major factor in Ca2+-dipicolinic acid (DPA)-triggered germination, but its enzymatic activity remains unidentified because its products are large and not readily released from the spore's integuments. CwlJ2 contributes the least to overall cortex digestion but plays a subsidiary role in Ca2+-DPA-induced germination. SleL is an N-acetylglucosaminidase that plays the major role in hydrolyzing the large products of other GSLEs into small, rapidly released muropeptides. As the roles of these enzymes in cortex degradation become clearer, they will be targets for methods to stimulate premature germination of B. anthracis spores, greatly simplifying decontamination measures.

scholarly journals High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Zhang ◽  
Changjiu Sun ◽  
Tingwei He ◽  
Yuanzhi Jiang ◽  
Junli Wei ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Structural Characteristics ◽  
Quantum Yields ◽  
Research Directions ◽  
Light Emitting ◽  
Perovskite Materials ◽  
Quantum Confinement Effects ◽  
Semiconducting Properties

AbstractQuasi-two-dimensional (quasi-2D) perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation light-emitting diodes (LEDs). The outstanding optical properties originate from their structural characteristics. In particular, the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectric- and quantum-confinement effects; the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields (PLQYs), particularly at low excitation intensities. The review herein presents an overview of the inherent properties of quasi-2D perovskite materials, the corresponding energy transfer and spectral tunability methodologies for thin films, as well as their application in high-performance LEDs. We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs. The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.

scholarly journals Optimization of sunflower head pectin extraction by ammonium oxalate and the effect of drying conditions on properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xuemei Ma ◽  
Jiayi Yu ◽  
Jing Jing ◽  
Qian Zhao ◽  
Liyong Ren ◽  
...  
Keyword(s):  
High Performance ◽  
Freeze Drying ◽  
Antioxidant Activities ◽  
Structural Characteristics ◽  
Radical Scavenging ◽  
Ammonium Oxalate ◽  
Extraction Process ◽  
Size Exclusion ◽  
Pharmaceutical Industries

AbstractPectin is a kind of natural and complex carbohydrates which is extensively used in food, chemical, cosmetic, and pharmaceutical industries. Fresh sunflower (Helianthus annuus L.) heads were utilized as a novel source of pectin extracted by ammonium oxalate. The conditions of the extraction process were optimized implementing the response surface methodology. Under optimal extraction parameters (extraction time 1.34 h, liquid–solid ratio 15:1 mL/g, ammonium oxalate concentration 0.76% (w/v)), the maximum experimental yield was 7.36%. The effect of spray-drying and freeze-drying on the physiochemical properties, structural characteristics, and antioxidant activities was investigated by FT-IR spectroscopy, high performance size exclusion chromatography, and X-ray diffraction. The results showed freeze-drying lead to decrease in galacturonic acid (GalA) content (76.2%), molecular weight (Mw 316 kDa), and crystallinity. The antioxidant activities of pectin were investigated utilizing the in-vitro DPPH and ABTS radical-scavenging systems. This study provided a novel and efficient extraction method of sunflower pectin, and confirmed that different drying processes had an effect on the structure and properties of pectin.

scholarly journals The PKS4 Gene of Fusarium graminearum Is Essential for Zearalenone Production

2006 ◽  
Vol 72 (6) ◽  
pp. 3924-3932 ◽  
Author(s):  
Erik Lys�e ◽  
Sonja S. Klemsdal ◽  
Karen R. Bone ◽  
Rasmus J. N. Frandsen ◽  
Thomas Johansen ◽  
...  
Keyword(s):  
Fusarium Graminearum ◽  
High Performance ◽  
Polyketide Synthase ◽  
Wild Type ◽  
Root Infection ◽  
Enoyl Reductase ◽  
Transformation Protocol ◽  
Chromatography Analysis ◽  
In The Wild ◽  
High Level

ABSTRACT Zearalenones are produced by several Fusarium species and can cause reproductive problems in animals. Some aurofusarin mutants of Fusarium pseudograminearum produce elevated levels of zearalenone (ZON), one of the estrogenic mycotoxins comprising the zearalenones. An analysis of transcripts from polyketide synthase genes identified in the Fusarium graminearum database was carried out for these mutants. PKS4 was the only gene with an enoyl reductase domain that had a higher level of transcription in the aurofusarin mutants than in the wild type. An Agrobacterium tumefaciens-mediated transformation protocol was used to replace the central part of the PKS4 gene with a hygB resistance gene through double homologous recombination in an F. graminearum strain producing a high level of ZON. PCR and Southern analysis of transformants were used to identify isolates with single insertional replacements of PKS4. High-performance liquid chromatography analysis showed that the PKS4 replacement mutant did not produce ZON. Thus, PKS4 encodes an enzyme required for the production of ZON in F. graminearum. Barley root infection studies revealed no alteration in the pathogenicity of the PKS4 mutant compared to the pathogenicity of the wild type. The expression of PKS13, which is located in the same cluster as PKS4, decreased dramatically in the mutant, while transcription of PKS4 was unchanged. This differential expression may indicate that ZON or its derivatives do not regulate expression of PKS4 and that the PKS4-encoded protein or its product stimulates expression of PKS13. Furthermore, both the lack of aurofusarin and ZON influenced the expression of other polyketide synthases, demonstrating that one polyketide can influence the expression of others.

Morphology and Structure Induced Co3O4 Nanowires High-Performance Supercapacitor Electrode Material

2021 ◽  
Vol 16 (6) ◽  
pp. 1005-1010
Author(s):  
Jian Wang ◽  
Yan Zhao ◽  
Yucai Li ◽  
Shiwei Song
Keyword(s):  
Electrochemical Performance ◽  
High Performance ◽  
Structural Characteristics ◽  
High Porosity ◽  
Ni Foam ◽  
Supercapacitor Electrode ◽  
Morphology And Structure ◽  
Hydrothermal Approach ◽  
Large Capacitance ◽  
Superior Cycling Stability

The electrochemical performance of the material depends heavily on the morphologies and structural characteristics of the material. Co3O4 samples show the remarkable electrochemical performance owing to the high porosity, appropriate pore size distribution and novel architecture and the effect of NH4F for morphology. Co3O4 nanowires grown on Ni foam have been synthesized through a facile hydrothermal approach, revealing large capacitance of 2178.4 mF cm−2 at the current density of 2 mA cm−2 and superior cycling stability.

Lignin-based polymers

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Fan Qi ◽  
Zhang Chaoqun ◽  
Yang Weijun ◽  
Wang Qingwen ◽  
Ou Rongxian
Keyword(s):  
High Performance ◽  
Raw Materials ◽  
Structural Characteristics ◽  
Low Cost ◽  
Polymer Matrices ◽  
Terrestrial Plants ◽  
Polyester Resins ◽  
Sustainable Resources ◽  
Reinforced Polymer ◽  
New Ideas

Abstract On the basis of the world’s continuing consumption of raw materials, there was an urgent need to seek sustainable resources. Lignin, the second naturally abundant biomass, accounts for 15–35% of the cell walls of terrestrial plants and is considered waste for low-cost applications such as thermal and electricity generation. The impressive characteristics of lignin, such as its high abundance, low density, biodegradability, antioxidation, antibacterial capability, and its CO2 neutrality and enhancement, render it an ideal candidate for developing new polymer/composite materials. In past decades, considerable works have been conducted to effectively utilize waste lignin as a component in polymer matrices for the production of high-performance lignin-based polymers. This chapter is intended to provide an overview of the recent advances and challenges involving lignin-based polymers utilizing lignin macromonomer and its derived monolignols. These lignin-based polymers include phenol resins, polyurethane resins, polyester resins, epoxy resins, etc. The structural characteristics and functions of lignin-based polymers are discussed in each section. In addition, we also try to divide various lignin reinforced polymer composites into different polymer matrices, which can be separated into thermoplastics, rubber, and thermosets composites. This chapter is expected to increase the interest of researchers worldwide in lignin-based polymers and develop new ideas in this field.

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