scholarly journals Functional Genomic and Biochemical Analysis Reveals Pleiotropic Effect of Congo Red on Aspergillus fumigatus

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Zhonghua Liu ◽  
Shriya Raj ◽  
Norman van Rhijn ◽  
Marcin Fraczek ◽  
Jean-Philippe Michel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Congo Red ◽  
Specific Binding ◽  
Cell Membrane Permeability ◽  
Growth Effect ◽  
Wall Structure ◽  
Cell Wall Polysaccharide ◽  
Resistant Mutants

ABSTRACT Inhibition of fungal growth by Congo red (CR) has been putatively associated with specific binding to β-1,3-glucans, which blocks cell wall polysaccharide synthesis. In this study, we searched for transcription factors (TFs) that regulate the response to CR and interrogated their regulon. During the investigation of the susceptibility to CR of the TF mutant library, several CR-resistant and -hypersensitive mutants were discovered and further studied. Abnormal distorted swollen conidia called Quasimodo cells were seen in the presence of CR. Quasimodo cells in the resistant mutants were larger than the ones in the sensitive and parental strains; consequently, the conidia of the resistant mutants absorbed more CR than the germinating conidia of the sensitive or parental strains. Accordingly, this higher absorption rate by Quasimodo cells resulted in the removal of CR from the culture medium, allowing a subset of conidia to germinate and grow. In contrast, all resting conidia of the sensitive mutants and the parental strain were killed. This result indicated that the heterogeneity of the conidial population is essential to promote the survival of Aspergillus fumigatus in the presence of CR. Moreover, amorphous surface cell wall polysaccharides such as galactosaminogalactan control the influx of CR inside the cells and, accordingly, resistance to the drug. Finally, long-term incubation with CR led to the discovery of a new CR-induced growth effect, called drug-induced growth stimulation (DIGS), since the growth of one of them could be stimulated after recovery from CR stress. IMPORTANCE The compound Congo red (CR) has been historically used for coloring treatment and histological examination as well to inhibit the growth of yeast and filamentous fungi. It has been thought that CR binds to β-1,3-glucans in the fungal cell wall, disrupting the organization of the cell wall structure. However, other processes have been implicated in affecting CR sensitivity. Here, we explore CR susceptibility through screening a library of genetic null mutants. We find several previously uncharacterized genetic regulators important for CR susceptibility. Through biochemical and molecular characterization, we find cell membrane permeability to be important. Additionally, we characterize a novel cell type, Quasimodo cells, that occurs upon CR exposure. These cells take up CR, allowing the growth of the remaining fungi. Finally, we find that priming with CR can enhance long-term growth in one mutant.

scholarly journals Gradual Alterations in Cell Wall Structure and Metabolism in Vancomycin-Resistant Mutants ofStaphylococcus aureus

1999 ◽  
Vol 181 (24) ◽  
pp. 7566-7570 ◽  
Author(s):  
Krzysztof Sieradzki ◽  
Alexander Tomasz
Keyword(s):  
Cell Wall ◽  
Methicillin Resistance ◽  
Specific Inhibitor ◽  
Wall Structure ◽  
Penicillin Binding Protein ◽  
Cell Wall Metabolism ◽  
Gradual Reduction ◽  
Vancomycin Resistant ◽  
Resistant Mutants ◽  
Structure And Metabolism

ABSTRACT In five vancomycin-resistant laboratory step mutants selected from the highly and homogeneously methicillin-resistant Staphylococcus aureus strain COL (MIC of methicillin, 800 μg/ml; MIC of vancomycin, 1.5 μg/ml), the gradually increasing levels of resistance to vancomycin were accompanied by parallel decreases in the levels of methicillin resistance and abnormalities in cell wall metabolism. The latter included a gradual reduction in the proportion of highly cross-linked muropeptide species in peptidoglycan, down-regulation of the production of penicillin-binding protein 2A (PBP2A) and PBP4, and hypersensitivity to β-lactam antibiotics each with a relatively selective affinity for the various staphylococcal PBPs; the PBP2-specific inhibitor ceftizoxime was particularly effective.

Congo Red Effect on Cyst Viability and Cell Wall Structure of Encysting Entamoeba invadens

1999 ◽  
Vol 30 (2) ◽  
pp. 106-115 ◽  
Author(s):  
Alejandra Guadalupe Garcı́a-Zapién ◽  
Arturo González-Robles ◽  
Juan Mora-Galindo
Keyword(s):  
Cell Wall ◽  
Congo Red ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Cyst Viability ◽  
Entamoeba Invadens

scholarly journals Novel Biological Functions of the NsdC Transcription Factor in Aspergillus fumigatus

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Patrícia Alves de Castro ◽  
Clara Valero ◽  
Jéssica Chiaratto ◽  
Ana Cristina Colabardini ◽  
Lakhansing Pardeshi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Sexual Reproduction ◽  
Rna Polymerase Ii ◽  
Vegetative Growth ◽  
Wall Structure ◽  
Immune Recognition ◽  
Biological Functions ◽  
Content Type

ABSTRACT The fungal zinc finger transcription factor NsdC is named after, and is best known for, its essential role in sexual reproduction (never in sexual development). In previous studies with Aspergillus nidulans, it was also shown to have roles in promotion of vegetative growth and suppression of asexual conidiation. In this study, the function of the nsdC homologue in the opportunistic human pathogen A. fumigatus was investigated. NsdC was again found to be essential for sexual development, with deletion of the nsdC gene in both MAT1-1 and MAT1-2 mating partners of a cross leading to complete loss of fertility. However, a functional copy of nsdC in one mating partner was sufficient to allow sexual reproduction. Deletion of nsdC also led to decreased vegetative growth and allowed conidiation in liquid cultures, again consistent with previous findings. However, NsdC in A. fumigatus was shown to have additional biological functions including response to calcium stress, correct organization of cell wall structure, and response to the cell wall stressors. Furthermore, virulence and host immune recognition were affected. Gene expression studies involving chromatin immunoprecipitation (ChIP) of RNA polymerase II (PolII) coupled to next-generation sequencing (Seq) revealed that deletion of nsdC resulted in changes in expression of over 620 genes under basal growth conditions. This demonstrated that this transcription factor mediates the activity of a wide variety of signaling and metabolic pathways and indicates that despite the naming of the gene, the promotion of sexual reproduction is just one among multiple roles of NsdC. IMPORTANCE Aspergillus fumigatus is an opportunistic human fungal pathogen and the main causal agent of invasive aspergillosis, a life-threatening infection especially in immunocompromised patients. A. fumigatus can undergo both asexual and sexual reproductive cycles, and the regulation of both cycles involves several genes and pathways. Here, we have characterized one of these genetic determinants, the NsdC transcription factor, which was initially identified in a screen of transcription factor null mutants showing sensitivity when exposed to high concentrations of calcium. In addition to its known essential roles in sexual reproduction and control of growth rate and asexual reproduction, we have shown in the present study that A. fumigatus NsdC transcription factor has additional previously unrecognized biological functions including calcium tolerance, cell wall stress response, and correct cell wall organization and functions in virulence and host immune recognition. Our results indicate that NsdC can play novel additional biological functions not directly related to its role played during sexual and asexual processes.

scholarly journals Biosynthesis of β-(1→5)-Galactofuranosyl Chains of Fungal-Type and O-Mannose-Type Galactomannans within the Invasive Pathogen Aspergillus fumigatus

2019 ◽  
Author(s):  
Yuria Chihara ◽  
Yutaka Tanaka ◽  
Minoru Izumi ◽  
Daisuke Hagiwara ◽  
Akira Watanabe ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Aspergillus Fumigatus ◽  
Pathogenic Fungus ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Wall Structure ◽  
Fungal Cell ◽  
Animal Pathogens

ABSTRACTThe pathogenic fungus Aspergillus fumigatus contains galactomannans localized on the surface layer of its cell walls, which are involved in various biological processes. Galactomannans comprise α-(1→2)-/α-(1→6)-mannan and β-(1→5)-/β-(1→6)-galactofuranosyl chains. We previously revealed that GfsA is a β-galactofuranoside β-(1→5)-galactofuranosyltransferase involved in the biosynthesis of β-(1→5)-galactofuranosyl chains. Here, we clarified the entire biosynthesis of β-(1→5)-galactofuranosyl chains in A. fumigatgus. Two paralogs exist within A. fumigatus: GfsB and GfsC. We show that GfsB and GfsC, in addition to GfsA, are β-galactofuranoside β-(1→5)-galactofuranosyltransferases by biochemical and genetic analyses. GfsA, GfsB, and GfsC can synthesize β-(1→5)-galactofuranosyl oligomers up to lengths of 7, 3, and 5 galactofuranoses within an established in vitro highly efficient assay of galactofuranosyltransferase activity. Structural analyses of galactomannans extracted from the strains ΔgfsB, ΔgfsC, ΔgfsAC, and ΔgfsABC revealed that GfsA and GfsC synthesized all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans, and GfsB exhibited limited function in A. fumigatus. The loss of β-(1→5)-galactofuranosyl residues decreased the hyphal growth rate and conidia formation ability as well as increased the abnormal hyphal branching structure and cell surface hydrophobicity, but this loss is dispensable for sensitivity to antifungal agents and virulence toward immune-compromised mice.IMPORTANCEβ-(1→5)-galactofuranosyl residues are widely distributed in the subphylum Pezisomycotina of the phylum Ascomycota. Pezizomycotina includes many plant and animal pathogens. Although the structure of β-(1→5)-galactofuranosyl residues of galactomannans in filamentous fungi was discovered long ago, it remains unclear which enzyme is responsible for biosynthesis of this glycan. Fungal cell wall formation processes are complicated, and information concerning glycosyltransferases is essential for their understanding. In this study, we show that GfsA and GfsC are responsible for the biosynthesis of all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans. The data presented here indicates that β-(1→5)-galactofuranosyl residues are involved in cell growth, conidiation, polarity, and cell surface hydrophobicity. Our new understanding of β-(1→5)-galactofuranosyl residue biosynthesis provides important novel insights into the formation of the complex cell wall structure and the virulence of the subphylum Pezisomycotina.

scholarly journals EglC, a New Endoglucanase from Aspergillus niger with Major Activity towards Xyloglucan

2002 ◽  
Vol 68 (4) ◽  
pp. 1556-1560 ◽  
Author(s):  
Alinda A. Hasper ◽  
Ester Dekkers ◽  
Marc van Mil ◽  
Peter J. I. van de Vondervoort ◽  
Leo H. de Graaff
Keyword(s):  
Cell Wall ◽  
Aspergillus Niger ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Binding Domain ◽  
Wall Structure ◽  
Glycoside Hydrolase Family ◽  
Cell Wall Polysaccharide ◽  
Cellulose Binding Domain ◽  
Cellulose Binding

ABSTRACT A novel gene, eglC, encoding an endoglucanase, was cloned from Aspergillus niger. Transcription of eglC is regulated by XlnR, a transcriptional activator that controls the degradation of polysaccharides in plant cell walls. EglC is an 858-amino-acid protein and contains a conserved C-terminal cellulose-binding domain. EglC can be classified in glycoside hydrolase family 74. No homology to any of the endoglucanases from Trichoderma reesei was found. In the plant cell wall xyloglucan is closely linked to cellulose fibrils. We hypothesize that the EglC cellulose-binding domain anchors the enzyme to the cellulose chains while it is cleaving the xyloglucan backbone. By this action it may contribute to the degradation of the plant cell wall structure together with other enzymes, including hemicellulases and cellulases. EglC is most active towards xyloglucan and therefore is functionally different from the other two endoglucanases from A. niger, EglA and EglB, which exhibit the greatest activity towards β-glucan. Although the mode of action of EglC is not known, this enzyme represents a new enzyme function involved in plant cell wall polysaccharide degradation by A. niger.

scholarly journals The Influence of Hydrolytic Enzymes on Tannin Adsorption-Desorption onto Grape Cell Walls in a Wine-Like Matrix

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 770
Author(s):  
Andrea Osete-Alcaraz ◽  
Encarna Gómez-Plaza ◽  
Pilar Martínez-Pérez ◽  
Florent Weiller ◽  
Julia Schückel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Practical Importance ◽  
Hydrolytic Enzymes ◽  
Cell Wall Structure ◽  
Size Exclusion ◽  
Wall Structure ◽  
Cell Wall Polysaccharide ◽  
Desorption Process ◽  
Grape Cell

This study evaluates the capacity of four hydrolytic enzymes to limit the interactions between grape cell-walls and tannins and/or to favor tannin desorption. Adsorption and desorption tests were conducted by mixing a commercial seed tannin with purified skin cell-walls from Syrah grapes, in the presence or absence of hydrolytic enzymes, in a model-wine solution. The effects of the enzymes were evaluated by measuring the tannins in solution by High Performance Liquid Chromatography (HPLC) and the changes in the cell wall polysaccharide network by Comprehensive Microarray Polymer Profiling (COMPP) while the polysaccharides liberated from cell walls were analyzed by Size Exclusion Chromatography (SEC). The results showed that the enzymes limited the interaction between tannins and cell walls, especially cellulase, pectinase and xylanase, an effect associated with the cell wall structural modifications caused by the enzymes, which reduced their capacity to bind tannins. With regards to the tannin desorption process, enzymes did not play a significant role in liberating bound tannins. Those enzymes that showed the highest effect in limiting the adsorption of tannins and in disorganizing the cell wall structure, cellulase and pectinase, did not lead to a desorption of bound tannins, although they still showed a capacity of affecting cell wall structure. The results indicate that enzymes are not able to access those polysaccharides where tannins are bound, thus, they are not a useful tool for desorbing tannins from cell walls. The practical importance implications of these findings are discussed in the manuscript.

scholarly journals Chitin Synthases with a Myosin Motor-Like Domain Control the Resistance of Aspergillus fumigatus to Echinocandins

2012 ◽  
Vol 56 (12) ◽  
pp. 6121-6131 ◽  
Author(s):  
Cristina Jiménez-Ortigosa ◽  
Vishukumar Aimanianda ◽  
Laetitia Muszkieta ◽  
Isabelle Mouyna ◽  
David Alsteens ◽  
...  
Keyword(s):  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Mutant Strain ◽  
Parental Strain ◽  
Amorphous Material ◽  
Wall Structure ◽  
Slight Reduction ◽  
Myosin Motor ◽  
Chitin Content ◽  
Chitin Synthases

ABSTRACTAspergillus fumigatushas two chitin synthases (CSMAandCSMB) with a myosin motor-like domain (MMD) arranged in a head-to-head configuration. To understand the function of these chitin synthases, single and doublecsmmutant strains were constructed and analyzed. Although there was a slight reduction in mycelial growth of the mutants, the total chitin synthase activity and the cell wall chitin content were similar in the mycelium of all of the mutants and the parental strain. In the conidia, chitin content in the ΔcsmAstrain cell wall was less than half the amount found in the parental strain. In contrast, the ΔcsmBmutant strain and, unexpectedly, the ΔcsmA/ΔcsmBmutant strain did not show any modification of chitin content in their conidial cell walls. In contrast to the hydrophobic conidia of the parental strain, conidia of all of thecsmmutants were hydrophilic due to the presence of an amorphous material covering the hydrophobic surface-rodlet layer. The deletion ofCSMgenes also resulted in an increased susceptibility of resting and germinating conidia to echinocandins. These results show that the deletion of theCSMAandCSMBgenes induced a significant disorganization of the cell wall structure, even though they contribute only weakly to the overall cell wall chitin synthesis.

scholarly journals The synthesis of xyloglucan, an abundant plant cell wall polysaccharide, requires CSLC function

2020 ◽  
Vol 117 (33) ◽  
pp. 20316-20324 ◽  
Author(s):  
Sang-Jin Kim ◽  
Balakumaran Chandrasekar ◽  
Anne C. Rea ◽  
Linda Danhof ◽  
Starla Zemelis-Durfee ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Reverse Genetics ◽  
Plant Cell Wall ◽  
Phylogenetic Analyses ◽  
Higher Order ◽  
Wall Structure ◽  
Cell Wall Polysaccharide ◽  
Apparent Lack

Xyloglucan (XyG) is an abundant component of the primary cell walls of most plants. While the structure of XyG has been well studied, much remains to be learned about its biosynthesis. Here we employed reverse genetics to investigate the role ofArabidopsiscellulose synthase like-C (CSLC) proteins in XyG biosynthesis. We found that single mutants containing a T-DNA in each of the fiveArabidopsis CSLCgenes had normal levels of XyG. However, higher-ordercslcmutants had significantly reduced XyG levels, and a mutant with disruptions in all fiveCSLCgenes had no detectable XyG. The higher-order mutants grew with mild tissue-specific phenotypes. Despite the apparent lack of XyG, thecslcquintuple mutant did not display significant alteration of gene expression at the whole-genome level, excluding transcriptional compensation. The quintuple mutant could be complemented by each of the fiveCSLCgenes, supporting the conclusion that each of them encodes a XyG glucan synthase. Phylogenetic analyses indicated that theCSLCgenes are widespread in the plant kingdom and evolved from an ancient family. These results establish the role of theCSLCgenes in XyG biosynthesis, and the mutants described here provide valuable tools with which to study both the molecular details of XyG biosynthesis and the role of XyG in plant cell wall structure and function.

scholarly journals Correlation between bacterial decay and chemical changes in waterlogged archaeological wood analysed by light microscopy and Py-GC/MS

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nanna Bjerregaard Pedersen ◽  
Jeannette Jacqueline Łucejko ◽  
Francesca Modugno ◽  
Charlotte Björdal
Keyword(s):  
Cell Wall ◽  
Light Microscopy ◽  
Gas Chromatography Mass Spectrometry ◽  
Wall Structure ◽  
Chemical Changes ◽  
Residual Structure ◽  
Archaeological Wood ◽  
Waterlogged Archaeological Wood ◽  
Bacterial Decay

AbstractErosion bacteria are the main degraders of archaeological wood excavated from waterlogged environments. Light microscopy and analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) were exploited to study waterlogged archaeological wood (Pinus sylvestris L.) at different stages of bacterial decay. The research explored the biochemical changes related to erosion bacteria degradation of the secondary cell wall in the wood cells and the chemical changes related to abiotic processes induced by the long-term waterlogged burial environment. Erosion bacteria were demonstrated by chemical analysis to cause significant holocellulose depletion. Detailed analysis of the holocellulose and lignin pyrolysis products revealed only minor chemical changes in the residual structure even after heavy erosion bacteria decay. Chemical changes in the lignin polymer is associated to enzymatic unlocking of the lignocellulose to gain access to the holocellulose fraction of the cell wall. Chemical changes in the holocellulose fraction are suggested to stem from depolymerisation and from alterations in the polymer matrix of the residual wood cell wall structure. Interestingly, a difference was observed between the sound reference wood and the waterlogged archaeological wood without erosion bacteria decay, indicating that long-term exposure in waterlogged environments results in partial decay of the holocellulose even in absence of bacterial activity.

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