scholarly journals Candida albicans phosphate transport, facilitating nucleotide sugar biosynthesis, contributes to cell wall stability.

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Maikel Acosta-Zaldivar ◽  
Wanjun Qi ◽  
Ning-Ning Liu ◽  
Joann Diray-Arce ◽  
Louise A. Walker ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Enzymatic Reaction ◽  
Phosphate Starvation ◽  
Reaction Rates ◽  
Outer Cell ◽  
Cell Wall Polysaccharides ◽  
Nucleotide Sugar ◽  
Structural Cell ◽  
Chitin Synthases

The Candida albicans high-affinity phosphate transporter Pho84 is required for normal Target of Rapamycin signaling, oxidative stress resistance and virulence of this fungal pathogen. It also contributes to C. albicans’ tolerance of two antifungal drug classes, polyenes and echinocandins. Echinocandins inhibit biosynthesis of a major cell wall component, beta-1,3-glucan. Cells lacking Pho84 were hypersensitive to other forms of cell wall stress beyond echinocandin exposure, while their cell wall integrity signaling response was weak. Metabolomics experiments showed that levels of phosphoric intermediates, including nucleotides like ATP and nucleotide sugars, were low in pho84 mutant compared to wild type cells recovering from phosphate starvation. Non-phosphoric precursors like nucleobases and nucleosides were elevated. Outer cell wall phosphomannan biosynthesis requires a nucleotide sugar,GDP-mannose. The nucleotide sugar UDP-glucose is the substrate of enzymes that synthesize two major structural cell wall polysaccharides, beta-1,3- and beta-1,6-glucan. Another nucleotide sugar, UDP-N-acetylglucosamine, is the substrate of chitin synthases which produce a stabilizing component of the intercellular septum and of lateral cell walls. Lack of Pho84 activity, and phosphate starvation, potentiated pharmacological or genetic perturbation of these enzymes. Our model is that low substrate concentrations of beta-D-glucan- and chitin synthases diminish enzymatic reaction rates and potentiate pharmacologic inhibitors to decrease the yield of their cell wall-stabilizing products. Phosphate import is not conserved between fungal and human cells, and humans do not synthesize beta-D-glucans or chitin. Hence inhibiting these processes simultaneously could yield potent antifungal effects with low toxicity to humans.

scholarly journals Phosphoric Metabolites Link Phosphate Import and Polysaccharide Biosynthesis for Candida albicans Cell Wall Maintenance

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Ning-Ning Liu ◽  
Maikel Acosta-Zaldívar ◽  
Wanjun Qi ◽  
Joann Diray-Arce ◽  
Louise A. Walker ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Stress Resistance ◽  
Wall Stress ◽  
Phosphate Starvation ◽  
Nucleotide Sugar ◽  
Content Type ◽  
Cell Wall Stress ◽  
Chitin Synthases ◽  
Nucleotide Sugars

ABSTRACT The Candida albicans high-affinity phosphate transporter Pho84 is required for normal Target of Rapamycin (TOR) signaling, oxidative stress resistance, and virulence of this fungal pathogen. It also contributes to C. albicans’ tolerance of two antifungal drug classes, polyenes and echinocandins. Echinocandins inhibit biosynthesis of a major cell wall component, beta-1,3-glucan. Cells lacking Pho84 were hypersensitive to other forms of cell wall stress beyond echinocandin exposure, while their cell wall integrity signaling response was weak. Metabolomics experiments showed that levels of phosphoric intermediates, including nucleotides like ATP and nucleotide sugars, were low in pho84 mutant compared to wild-type cells recovering from phosphate starvation. Nonphosphoric precursors like nucleobases and nucleosides were elevated. Outer cell wall phosphomannan biosynthesis requires a nucleotide sugar, GDP-mannose. The nucleotide sugar UDP-glucose is the substrate of enzymes that synthesize two major structural cell wall polysaccharides, beta-1,3- and beta-1,6-glucan. Another nucleotide sugar, UDP-N-acetylglucosamine, is the substrate of chitin synthases which produce a stabilizing component of the intercellular septum and of lateral cell walls. Lack of Pho84 activity, and phosphate starvation, potentiated pharmacological or genetic perturbation of these enzymes. We posit that low substrate concentrations of beta-d-glucan- and chitin synthases, together with pharmacologic inhibition of their activity, diminish enzymatic reaction rates as well as the yield of their cell wall-stabilizing products. Phosphate import is not conserved between fungal and human cells, and humans do not synthesize beta-d-glucans or chitin. Hence, inhibiting these processes simultaneously could yield potent antifungal effects with low toxicity to humans. IMPORTANCE Candida species cause hundreds of thousands of invasive infections with high mortality each year. Developing novel antifungal agents is challenging due to the many similarities between fungal and human cells. Maintaining phosphate balance is essential for all organisms but is achieved completely differently by fungi and humans. A protein that imports phosphate into fungal cells, Pho84, is not present in humans and is required for normal cell wall stress resistance and cell wall integrity signaling in C. albicans. Nucleotide sugars, which are phosphate-containing building block molecules for construction of the cell wall, are diminished in cells lacking Pho84. Cell wall-constructing enzymes may be slowed by lack of these building blocks, in addition to being inhibited by drugs. Combined targeting of Pho84 and cell wall-constructing enzymes may provide a strategy for antifungal therapy by which two sequential steps of cell wall maintenance are blocked for greater potency.

scholarly journals MODIFIKASI PRINSIP PEMERIKSAAN β-D-GLUCAN UNTUK MENDETEKSI CANDIDA ALBICANS DALAM SERUM

2016 ◽  
Vol 19 (3) ◽  
pp. 146
Author(s):  
Ruben Dharmawan ◽  
Darukutni Darukutni ◽  
Sri Haryati ◽  
Murkati Murkati ◽  
Yulia Sari ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Blood Serum ◽  
General Hospital ◽  
Drug Administration ◽  
Human Blood ◽  
Food And Drug Administration ◽  
Enzymatic Reaction ◽  
Human Blood Serum ◽  
The Cost

Candida albicans β-D-glucans examination has been used for invasive fungal detection in human blood and was approved by the Food and Drug Administration. However, the method is rarely used in Indonesia and also because the cost is hardly affordable. A modification of the method using enzymatic reaction is hoped will provide a simple and affordable measurement in human blood serum. β-D-glucans as heterogeneous molecules constitute the major carbohydrates fractions of cell wall and readily detected in supernatants of Candida albicans cultures are hydrolyzed by β glucanase to form D-glucose. This additional glucose is measured using Megazyme GOPOD-Format Procedure® at 510 nm. Candida albicans were identified and cultured was derived from a patient of Dr. Moewardi General Hospital, Surakarta in July, 2012. The results show that β-D-glucans from Candida albicans is measureable to the amount of μg/100 μL serum using this modification principle

scholarly journals The interaction between Carbohydrates and the Antimicrobial Peptide P-113Tri is Involved in the Killing of Candida albicans

2020 ◽  
Vol 8 (2) ◽  
pp. 299 ◽  
Author(s):  
Guan-Yu Lin ◽  
Chuan-Fa Chang ◽  
Chung-Yu Lan
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antimicrobial Peptide ◽  
Mammalian Cells ◽  
Peptide Binding ◽  
Antifungal Drugs ◽  
Planktonic Cells ◽  
Cell Wall Polysaccharides ◽  
The Difference ◽  
Competition Assays

The emergence of drug resistance to Candida albicans is problematic in the clinical setting. Therefore, developing new antifungal drugs is in high demand. Our previous work indicated that the antimicrobial peptide P-113Tri exhibited higher antifungal activity against planktonic cells, biofilm cells, and clinical isolates of Candida species compared to its parental peptide P-113. In this study, we further investigated the difference between these two peptides in their mechanisms against C. albicans. Microscopic examination showed that P-113 rapidly gained access to C. albicans cells. However, most of the P-113Tri remained on the cell surface. Moreover, using a range of cell wall-defective mutants and competition assays, the results indicated that phosphomannan and N-linked mannan in the cell wall are important for peptide binding to C. albicans cells. Furthermore, the addition of exogenous phosphosugars reduced the efficacy of the peptide, suggesting that negatively charged phosphosugars also contributed to the peptide binding to the cell wall polysaccharides. Finally, using a glycan array, P-113Tri, but not P-113, can bind to other glycans commonly present on other microbial and mammalian cells. Together, these results suggest that P-113 and P-113Tri have fundamental differences in their interaction with C. albicans and candidacidal activities.

THE CELL WALL POLYSACCHARIDES OF CANDIDA ALBICANS: GLUCAN, MANNAN, AND CHITIN

1960 ◽  
Vol 38 (6) ◽  
pp. 869-881 ◽  
Author(s):  
C. T. Bishop ◽  
F. Blank ◽  
P. E. Gardner
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Copper Complexes ◽  
Moving Boundary ◽  
Periodate Oxidation ◽  
Borate Buffer ◽  
Cell Wall Polysaccharides ◽  
Pathogenic Yeast ◽  
Hydrolysis Of

Cells of Candida albicans, a pathogenic yeast, have been shown to contain, in addition to chitin, a glucan ([α]D − 30°) and a mannan ([α]D + 78°) in the approximate ratio of 1.00:0.64. The two polysaccharides were easily distinguishable by moving boundary electrophoresis in borate buffer and were separated from each other by fractionation of their copper complexes. Methylation and hydrolysis of the glucan yielded the following O-methyl ethers of D-glucose: 2,3,4,6-tetra-O-methyl (7 moles); 2,3,4-tri-O-methyl (13 moles); 2,4,6-tri-O-methyl (trace); 2,4-di-O-methyl (6 moles); and 2-O-methyl (1 mole). It was concluded that the glucan was a highly branched polysaccharide containing β 1 → 6 and β 1 → 3 linked residues. Periodate oxidation of the glucan supported this conclusion.Methylation and hydrolysis of the mannan yielded the following O-methyl ethers of D-mannose: 2,3,4,6-tetra-O-methyl (1.65 moles); 3,4,6-tri-O-methyl (1.00 mole); 2,3,6-tri-O-methyl (0.18 mole); 3,4-di-O-methyl (1.90 moles). The mannan was therefore a highly branched polysaccharide with short chains of α 1 → 2 linked mannose residues joined together by α 1 → 6 linkages. Results of periodate oxidation agreed with this structure.The differences between these two polysaccharides and glucans and mannans found in other yeasts are discussed.

scholarly journals Crosstalk between calcineurin and the cell wall integrity pathways prevents chitin overexpression in Candida albicans

2021 ◽  
Author(s):  
Alessandra da Silva Dantas ◽  
Filomena Nogueira ◽  
Keunsook K. Lee ◽  
Louise A. Walker ◽  
Matt Edmondson ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antifungal Drugs ◽  
Cell Wall Integrity ◽  
Yeast Cells ◽  
Outer Cell ◽  
Chitin Synthesis ◽  
Simultaneous Activation ◽  
Glucan Synthesis ◽  
Calcineurin Pathway

Echinocandins such as caspofungin are front line antifungal drugs that compromise β-1,3 glucan synthesis in the cell wall. Recent reports have shown that fungal cells can resist killing by caspofungin by up-regulation of chitin synthesis, thereby sustaining cell wall integrity. When echinocandins are removed, the chitin content of cells quickly returns to basal levels, suggesting that there is a fitness cost associated with having elevated levels of chitin in the cell wall. We show here that simultaneous activation of the calcineurin and CWI pathways generates a sub-population of Candida albicans yeast cells that have supra-normal chitin levels interspersed throughout the inner and outer cell wall, and that these cells are non-viable, perhaps due to loss of wall elasticity required for cell expansion and growth. Mutations in the Ca2+-calcineurin pathway prevented the formation of these non-viable super high chitin cells by negatively regulating chitin synthesis driven by the CWI pathway. The Ca2+-calcineurin pathway may therefore act as an attenuator that prevents the overproduction of chitin by coordinating both chitin upregulation and negative regulation of the CWI signaling pathway.

High Pressure Freezing/Freeze Substituion: Comparison of Chemical Fixation Versus Cryoimmobilization of Candida Albicans Cultured in Cellulose Tubing

1999 ◽  
Vol 5 (S2) ◽  
pp. 434-435
Author(s):  
S. Erlandsen ◽  
A Holzer ◽  
M. Gavin ◽  
C. Frethem ◽  
C. Wells
Keyword(s):  
High Pressure ◽  
Cell Wall ◽  
Candida Albicans ◽  
Freeze Substitution ◽  
Host Cells ◽  
Yeast Cells ◽  
Outer Cell ◽  
High Pressure Freezing ◽  
Outer Cell Wall

In the interactions of Candida albicans with host cells, the cell wall of the yeast may play important roles in the adhesion of yeast cells to tissues. The outer cell wall of yeast (e.g. Saccharomyces cerevisiae, C. albicans) has been shown to consist of a dense network of radially projecting fibrils composed of mannoproteins that are known as fimbriae and which previously have required cryopreservation either by jet propane freezing or by plunge freezeing for their visualization. High pressure freezing provides an advantage over jet or plunge freezing in terms of the higher consistancey in the quality of freezing, and the minimization of formation of ice I with this method. Hohenberg et al reported a method utilizing cellulose capillary tubes to cryoimmobilize suspensions of microoganisms by high pressure freezing (HPF) and freeze substitution (FS), and herein, we describe an adaptation of this method by culturing microorganisms within the tubing to increase cell density prior to high pressure freezing and freeze substution.

Characterization of structural cell wall polysaccharides in cattail (Typha latifolia): Evaluation as potential biofuel feedstock

2017 ◽  
Vol 175 ◽  
pp. 679-688 ◽  
Author(s):  
Diego Rebaque ◽  
Romina Martínez-Rubio ◽  
Silvia Fornalé ◽  
Penélope García-Angulo ◽  
Ana Alonso-Simón ◽  
...  
Keyword(s):  
Cell Wall ◽  
Typha Latifolia ◽  
Cell Wall Polysaccharides ◽  
Biofuel Feedstock ◽  
Structural Cell

scholarly journals Cell wall protection by the Candida albicans class I chitin synthases

2015 ◽  
Vol 82 ◽  
pp. 264-276 ◽  
Author(s):  
Kanya Preechasuth ◽  
Jeffrey C. Anderson ◽  
Scott C. Peck ◽  
Alistair J.P. Brown ◽  
Neil A.R. Gow ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Class I ◽  
Chitin Synthases

scholarly journals Candida albicans cell wall mannosidases, Dfg5 and Dcw1, regulate chitin synthesis

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Abhiram Maddi ◽  
Jaewon Kim ◽  
Harleen Sohi ◽  
Sujay Busarajan ◽  
Olga Glagovyak ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fluorescence Microscopy ◽  
Signaling Pathways ◽  
Cell Separation ◽  
Wild Type ◽  
Chitin Synthesis ◽  
Chitin Synthases ◽  
Conditional Mutant ◽  
Calcineurin Signaling

In Candida albicans chitin synthesis is important for cell wall integrity and may also have a role in emergence of drug-resistance. Our past studies showed that cell wall mannosidases, Dfg5 and Dcw1, regulate HOG MAPK signaling. In this study, we investigated how Dfg5 and Dcw1 regulate chitin synthesis by affecting HOG, PKC and Calcium-Calcineurin signaling pathways. DFG5 and DCW1 heterologous mutants (ES1 & ES195) and a conditional mutant (ES195+methionine/cysteine) were utilized. WT SC5314 served as negative control and Hog1 knock-out mutant as positive control. Fluorescence microscopy of calcofluor white (CFW) stained mutant and control strains was performed to observe chitin accumulation. Quantitative PCR analysis was performed to measure the relative expression of chitin synthases CHS1, CHS2, CHS3 and CHS8. Incubation with chitinase was done to determine cell separation using light microscopy and scanning electron microscopy (SEM) analysis. Fluorescence microscopy showed significantly increased chitin accumulation in the mutants as compared to wild type. Chitin accumulation was observed mainly at the budding sites indicating a cause for defective cell separation phenotype. Incubation with chitinase led to cell separation in the mutants. CHS2, CHS3 and CHS8 expression was observed to be significantly upregulated in the conditional mutant and HOG1 mutant as compared to the wild type. This upregulation was also observed when the cell wall integrity PKC pathway was activated. However, activation of the Calcium-calcineurin pathway downregulated chitin synthase expression in the mutants. Our data indicates that Dfg5 and Dcw1 regulate expression of chitin synthases via HOG MAPK, PKC and Calcium-calcineurin signaling pathways.

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