Antibacterial Activities of beta-Lactamase Inhibitors Associated with Morphological Changes of Cell Wall in Helicobacter pylori

The Center for Structural Genomics for Infectious Diseases (CSGID) applies structural genomics approaches to biomedically important proteins from human pathogens. It also provides the infectious disease community with a high throughput pipeline for structure determination that carries out all steps of the process, from target selection through structure deposition. Target proteins include drug targets, essential enzymes, virulence factors and vaccine candidates. The CSGID has deposited over 680 structures in the Protein Data Bank. The proteins that are exposed on the surface of Gram positive bacterial pathogens (including Staphylococcus aureus, Bacillus anthracis, Listeria monocytogenes, Streptococcus species and Clostridium species) have been one focus area for the CSGID. So far, the structures of more than 55 of these proteins have been determined. The surface proteins are important in the interactions between the pathogen and its host, but many of them are as yet functionally uncharacterized. Among the examples that will be presented is the Bacillus anthracis SpoIID protein. SpoIID is part of a coordinated cell wall degradation machine that is essential for sporulation and the morphological changes involved. It represents a new family of lytic transglycosylases that degrade the glycan strands of the peptidoglycan cell wall. The two active site clefts in the dimeric enzyme include residues from both subunits, suggesting that the dimer is required for activity. This project has been funded in whole or in part with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contracts No. HHSN272200700058C and HHSN272201200026C.

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Microstructure of thermally modified radiata pine wood

BioResources ◽

10.15376/biores.16.1.1523-1533 ◽

2020 ◽

Vol 16 (1) ◽

pp. 1523-1533

Author(s):

José Luis Cabezas-Romero ◽

Linette Salvo-Sepúlveda ◽

Helga Contreras-Moraga ◽

Natalia Pérez-Peña ◽

Víctor Sepúlveda-Villarroel ◽

...

Keyword(s):

Cell Wall ◽

Wood Cell Wall ◽

Morphological Changes ◽

Untreated Wood ◽

Radiata Pine ◽

Treatment Temperature ◽

Thermal Modification ◽

Modification Process ◽

Potential Alternative ◽

Two Temperatures

The thermal modification of wood is a potential alternative method for improving wood dimensional stability and increasing the resistance of wood to decay. However, during thermal modification, morphological changes occur within the microstructure of the cell, and these confer different properties to the wood. This study investigated the effects of the thermal modification process on the microstructure of radiata pine juvenile wood. Therefore, anatomical measurements were performed via optical microscopy in selected earlywood and latewood samples after each treatment, and the results were compared to untreated wood samples. In this study, two temperatures (190 °C and 210 °C) were considered for the thermal modification process. The results showed that the level of temperature of modification affected to microstructure of cell wall. The cell wall thickness decreased as treatment temperature increased, whereas the average lumen diameter increased slightly as temperature increased. Thermally modified radiata pine showed signs of damage (cracks, broken cells and deformations in the wood cell wall). The proportion of destroyed area increased as temperature increased, and significant differences were evident for the thermal treatment at 210 °C.

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An ABC transporter Wzm–Wzt catalyzes translocation of lipid-linked galactan across the plasma membrane in mycobacteria

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2023663118 ◽

2021 ◽

Vol 118 (17) ◽

pp. e2023663118

Author(s):

Karin Savková ◽

Stanislav Huszár ◽

Peter Baráth ◽

Zuzana Pakanová ◽

Stanislav Kozmon ◽

...

Keyword(s):

Cell Wall ◽

Plasma Membrane ◽

Abc Transporter ◽

Morphological Changes ◽

Transport Systems ◽

Host Immune System ◽

Mycolic Acids ◽

Cell Wall Biogenesis ◽

Covalently Linked ◽

High Level

Mycobacterium tuberculosis, one of the deadliest pathogens in human history, is distinguished by a unique, multilayered cell wall, which offers the bacterium a high level of protection from the attacks of the host immune system. The primary structure of the cell wall core, composed of covalently linked peptidoglycan, branched heteropolysaccharide arabinogalactan, and mycolic acids, is well known, and numerous enzymes involved in the biosynthesis of its components are characterized. The cell wall biogenesis takes place at both cytoplasmic and periplasmic faces of the plasma membrane, and only recently some of the specific transport systems translocating the metabolic intermediates between these two compartments have been characterized [M. Jackson, C. M. Stevens, L. Zhang, H. I. Zgurskaya, M. Niederweis, Chem. Rev., 10.1021/acs.chemrev.0c00869 (2020)]. In this work, we use CRISPR interference methodology in Mycobacterium smegmatis to functionally characterize an ATP-binding cassette (ABC) transporter involved in the translocation of galactan precursors across the plasma membrane. We show that genetic knockdown of the transmembrane subunit of the transporter results in severe morphological changes and the accumulation of an aberrantly long galactan precursor. Based on similarities with structures and functions of specific O-antigen ABC transporters of gram-negative bacteria [C. Whitfield, D. M. Williams, S. D. Kelly, J. Biol. Chem. 295, 10593-10609 (2020)], we propose a model for coupled synthesis and export of the galactan polymer precursor in mycobacteria.

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Morphological changes in putrefactive anaerobe 3679 (Clostridium sporogenes) induced by sorbate, hydrochloric acid, and nitrite

Canadian Journal of Microbiology ◽

10.1139/m89-060 ◽

1989 ◽

Vol 35 (3) ◽

pp. 388-398 ◽

Cited By ~ 5

Author(s):

Irene E. Ronning ◽

Hilmer A. Frank

Keyword(s):

Cell Wall ◽

Hydrochloric Acid ◽

Growth Regulation ◽

Morphological Changes ◽

Light And Electron Microscopy ◽

Normal Growth ◽

Outer Wall ◽

Exponential Growth Phase ◽

Clostridium Sporogenes ◽

Cellular Debris

Putrefactive anaerobe 3679 (Clostridium sporogenes), a gram-positive bacterium, was examined by light and electron microscopy during normal growth and in a medium containing sorbate (50 mM, pH 6.5), hydrochloric acid (pH of medium adjusted from 7 to 5 with HCl), or nitrite (1 mM, pH 7). During the early exponential growth phase, untreated cells were filamentous and nonseptate, but became septate later and divided when the culture entered the stationary phase. Untreated short and filamentous cells had a double-layered cell wall. Sorbate-treated cells were usually filamentous and nonseptate, but with distorted shapes characterized by numerous bends and bulges. Septation, when present, resulted in minicells. The inner cell wall appeared to be thickened and the outer wall was absent in many areas. Acid-treated cells were similar to sorbate-treated cells but contained septa. Considerable cellular debris was present in the suspension. Nitrite-treated cells were also filamentous, bent, and bulged but the cell wall appeared normal. Considerable cellular debris was also present in suspensions of nitrite-treated cells. Changes in morphology are discussed in relation to possible mechanisms of cell growth regulation and the inhibitory action of sorbate, acid, and nitrite.Key words: putrefactive anaerobe 3679, sorbate, hydrochloric acid, nitrite.

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Lactobacillus fermentum UCO-979C beneficially modulates the innate immune response triggered by Helicobacter pylori infection in vitro

Beneficial Microbes ◽

10.3920/bm2018.0019 ◽

2018 ◽

Vol 9 (5) ◽

pp. 829-841 ◽

Cited By ~ 7

Author(s):

V. Garcia-Castillo ◽

H. Zelaya ◽

A. Ilabaca ◽

M. Espinoza-Monje ◽

R. Komatsu ◽

...

Keyword(s):

Immune Response ◽

Helicobacter Pylori ◽

Epithelial Cells ◽

Morphological Changes ◽

Helicobacter Pylori Infection ◽

Lactobacillus Fermentum ◽

Gastric Tissue ◽

Gastric Epithelial Cells ◽

Ags Cells ◽

H Pylori

Helicobacter pylori infection is associated with important gastric pathologies. An aggressive proinflammatory immune response is generated in the gastric tissue infected with H. pylori, resulting in gastritis and a series of morphological changes that increase the susceptibility to cancer development. Probiotics could present an alternative solution to prevent or decrease H. pylori infection. Among them, the use of immunomodulatory lactic acid bacteria represents a promising option to reduce the severity of chronic inflammatory-mediated tissue damage and to improve protective immunity against H. pylori. We previously isolated Lactobacillus fermentum UCO-979C from human gastric tissue and demonstrated its capacity to reduce adhesion of H. pylori to human gastric epithelial cells (AGS cells). In this work, the ability of L. fermentum UCO-979C to modulate immune response in AGS cells and PMA phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 (human monocytic leukaemia) macrophages in response to H. pylori infection was evaluated. We demonstrated that the UCO-979C strain is able to differentially modulate the cytokine response of gastric epithelial cells and macrophages after H. pylori infection. Of note, L. fermentum UCO-979C was able to significantly reduce the production of inflammatory cytokines and chemokines in AGS and THP-1 cells as well as increase the levels of immunoregulatory cytokines, indicating a remarkable anti-inflammatory effect. These findings strongly support the probiotic potential of L. fermentum UCO-979C and provide evidence of its beneficial effects against the inflammatory damage induced by H. pylori infection. Although our findings should be proven in appropriate experiments in vivo, in both H. pylori infection animal models and human trials, the results of the present work provide a scientific rationale for the use of L. fermentum UCO-979C to prevent or reduce H. pylori-induced gastric inflammation in humans.

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Bactericidal and Anti-Biofilm Activity of Ethanol Extracts Derived from Selected Medicinal Plants against Streptococcus pyogenes

Molecules ◽

10.3390/molecules24061165 ◽

2019 ◽

Vol 24 (6) ◽

pp. 1165 ◽

Cited By ~ 7

Author(s):

Niluni Wijesundara ◽

H. Rupasinghe

Keyword(s):

Electron Microscopy ◽

Medicinal Plants ◽

Streptococcus Pyogenes ◽

Morphological Changes ◽

Antibacterial Activities ◽

Ultra Performance Liquid Chromatography ◽

Streptococcal Pharyngitis ◽

Licorice Root ◽

Purple Coneflower ◽

Ethanol Extracts

Background: There is a growing interest in medicinal plants which have been traditionally used for the treatment of human infections. This study assessed 14 ethanol extracts (EEs) on bacterial growth and biofilm formation of Streptococcus pyogenes. Methods: Constituent major phytochemicals in the extracts were identified using ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Micro-broth dilution and time-kill assays were used to determine antibacterial activities. Anti-biofilm activities were studied using MTT assay, and morphology of biofilms was observed by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was employed to visualize the ultra-cross section structure of bacteria treated with efficacious extracts. Results: Licorice root, purple coneflower flower, purple coneflower stem, sage leaves and slippery elm inner bark EEs were the most effective, with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of 62.5 μg/mL and 125 μg/mL, respectively. The minimum biofilm inhibitory concentration (MBIC) of extracts ranged from 31.5–250 μg/mL. Morphological changes were observed in treated biofilms compared to the untreated. The four most effective extracts exhibited the ability to induce degradation of bacterial cell wall and disintegration of the plasma membrane. Conclusion: We suggest that EEs of sage leaf and purple coneflower flower are promising candidates to be further investigated for developing alternative natural therapies for the management of streptococcal pharyngitis.

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Touch-induced seedling morphological changes are determined by ethylene-regulated pectin degradation

Science Advances ◽

10.1126/sciadv.abc9294 ◽

2020 ◽

Vol 6 (48) ◽

pp. eabc9294

Author(s):

Qingqing Wu ◽

Yue Li ◽

Mohan Lyu ◽

Yiwen Luo ◽

Hui Shi ◽

...

Keyword(s):

Cell Wall ◽

Morphological Changes ◽

Mechanical Forces ◽

Ethylene Signaling ◽

Pectin Degradation ◽

Force Microscopy ◽

Mechanical Responses ◽

Atomic Force ◽

Wall Stiffness ◽

Molecular Framework

How mechanical forces regulate plant growth is a fascinating and long-standing question. After germination underground, buried seedlings have to dynamically adjust their growth to respond to mechanical stimulation from soil barriers. Here, we designed a lid touch assay and used atomic force microscopy to investigate the mechanical responses of seedlings during soil emergence. Touching seedlings induced increases in cell wall stiffness and decreases in cell elongation, which were correlated with pectin degradation. We revealed that PGX3, which encodes a polygalacturonase, mediates touch-imposed alterations in the pectin matrix and the mechanics of morphogenesis. Furthermore, we found that ethylene signaling is activated by touch, and the transcription factor EIN3 directly associates with PGX3 promoter and is required for touch-repressed PGX3 expression. By uncovering the link between mechanical forces and cell wall remodeling established via the EIN3-PGX3 module, this work represents a key step in understanding the molecular framework of touch-induced morphological changes.

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Helicobacter pylori Peptidoglycan Modifications Confer Lysozyme Resistance and Contribute to Survival in the Host

mBio ◽

10.1128/mbio.00409-12 ◽

2012 ◽

Vol 3 (6) ◽

Cited By ~ 39

Author(s):

Ge Wang ◽

Leja F. Lo ◽

Lennart S. Forsberg ◽

Robert J. Maier

Keyword(s):

Cell Wall ◽

Helicobacter Pylori ◽

Double Mutant ◽

Lytic Enzyme ◽

Permeability Barrier ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Content Type ◽

H Pylori ◽

Modification Enzyme

ABSTRACTThe prominent host muramidase lysozyme cleaves bacterial peptidoglycan (PG), and the enzyme is abundant in mucosal secretions. The lytic enzyme susceptibility of Gram-negative bacteria and mechanisms they use to thwart lytic enzyme activity are poorly studied. We previously characterized aHelicobacter pyloriPG modification enzyme, an N-deacetylase (PgdA) involved in lysozyme resistance. In this study, another PG modification enzyme, a putative PG O-acetyltransferase (PatA), was identified. Mass spectral analysis of the purified PG demonstrated that apatAstrain contained a greatly reduced amount of acetylated muropeptides, indicating a role for PatA inH. pyloriPG O-acetylation. The PG modification mutant strains (pgdA,patA, orpgdA patA) were more susceptible to lysozyme killing than the parent, but this assay required high lysozyme levels (up to 50 mg/ml). However, addition of host lactoferrin conferred lysozyme sensitivity toH. pylori, at physiologically relevant concentrations of both host components (3 mg/ml lactoferrin plus 0.3 mg/ml lysozyme). ThepgdA patAdouble mutant strain was far more susceptible to lysozyme/lactoferrin killing than the parent. Peptidoglycan purified from apgdA patAmutant was five times more sensitive to lysozyme than PG from the parent strain, while PG from both single mutants displayed intermediate sensitivity. Both sensitivity assays for whole cells and for purified PGs indicated that the modifications mediated by PgdA and PatA have a synergistic effect, conferring lysozyme tolerance. In a mouse infection model, significant colonization deficiency was observed for the double mutant at 3 weeks postinoculation. The results show that PG modifications affect the survival of a Gram-negative pathogen.IMPORTANCEPathogenic bacteria evade host antibacterial enzymes by a variety of mechanisms, which include resisting lytic enzymes abundant in the host. Enzymatic modifications to peptidoglycan (PG, the site of action of lysozyme) are a known mechanism used by Gram-positive bacteria to protect against host lysozyme attack. However, Gram-negative bacteria contain a thin layer of PG and a recalcitrant outer membrane permeability barrier to resist lysis, so molecular modifications to cell wall structure in order to combat lysis remain largely unstudied. Here we show that twoHelicobacter pyloriPG modification enzymes (PgdA and PatA) confer a clear protective advantage to a Gram-negative bacterium. They protect the bacterium from lytic enzyme degradation, albeit via different PG modification activities. Many pathogens are Gram negative, so some would be expected to have a similar cell wall-modifying strategy. Understanding such strategies may be useful for combating pathogen growth.

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Beta-lactamase induction and cell wall metabolism in Gram-negative bacteria

Frontiers in Microbiology ◽

10.3389/fmicb.2013.00128 ◽

2013 ◽

Vol 4 ◽

Cited By ~ 69

Author(s):

Ximin Zeng ◽

Jun Lin

Keyword(s):

Cell Wall ◽

Gram Negative Bacteria ◽

Beta Lactamase ◽

Cell Wall Metabolism ◽

Gram Negative

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