Cell Wall-Modifying Antifungal Drugs

2019 ◽  
pp. 255-275
Author(s):  
David S. Perlin
Keyword(s):  
Cell Wall ◽  
Antifungal Drugs

The Regulatory Function of the Molecular Chaperone Hsp90 in the Cell Wall Integrity of Pathogenic Fungi

2018 ◽  
Vol 16 (1) ◽  
pp. 44-53
Author(s):  
Marina Campos Rocha ◽  
Camilla Alves Santos ◽  
Iran Malavazi
Keyword(s):  
Cell Wall ◽  
Antifungal Therapy ◽  
Molecular Chaperone ◽  
Regulatory Protein ◽  
Pathogenic Fungi ◽  
Antifungal Drugs ◽  
Cell Wall Integrity ◽  
Regulatory Function ◽  
Loss Of Function ◽  
Hsp90 Inhibition

Different signaling cascades including the Cell Wall Integrity (CWI), the High Osmolarity Glycerol (HOG) and the Ca2+/calcineurin pathways control the cell wall biosynthesis and remodeling in fungi. Pathogenic fungi, such as Aspergillus fumigatus and Candida albicans, greatly rely on these signaling circuits to cope with different sources of stress, including the cell wall stress evoked by antifungal drugs and the host’s response during infection. Hsp90 has been proposed as an important regulatory protein and an attractive target for antifungal therapy since it stabilizes major effector proteins that act in the CWI, HOG and Ca2+/calcineurin pathways. Data from the human pathogen C. albicans have provided solid evidence that loss-of-function of Hsp90 impairs the evolution of resistance to azoles and echinocandin drugs. In A. fumigatus, Hsp90 is also required for cell wall integrity maintenance, reinforcing a coordinated function of the CWI pathway and this essential molecular chaperone. In this review, we focus on the current information about how Hsp90 impacts the aforementioned signaling pathways and consequently the homeostasis and maintenance of the cell wall, highlighting this cellular event as a key mechanism underlying antifungal therapy based on Hsp90 inhibition.

scholarly journals Susceptibility Pattern of Caspofungin-Coated Gold Nanoparticles against Clinically Important Candida Species

2020 ◽  
Author(s):  
Zahra Salehi ◽  
Azam Fattahi ◽  
Ensieh lotfali ◽  
Abdolhassan Kazemi ◽  
Ali Shakeri-Zadeh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Cell Wall ◽  
Candida Species ◽  
Spherical Shape ◽  
Sem Analysis ◽  
Antifungal Drugs ◽  
Wall Structure ◽  
Candida Spp ◽  
Average Size

Purpose: The present study was performed to examine whether caspofungin-coated gold nanoparticles (CAS-AuNPs) may offer the right platform for sensitivity induction in resistant isolates. Methods: For the purpose of the study, a total of 58 archived Candida species were enrolled in the research. The identification of Candida spp. was performed using polymerase chain reaction-restriction fragment length polymorphism and HWP1 gene amplification approaches. The conjugated CAS-AuNPs were synthesized and then characterized using transmission electron microscopy (TEM) and Zetasizer system to determine their morphology, size, and charge. Furthermore, the efficacy of CAS, CAS-AuNPs conjugate, and AuNPs against Candida spp. was assessed based on the Clinical and Laboratory Standards Institute M60. Finally, the interaction of CAS-AuNPs with Candida element was evaluated via scanning electron microscopy (SEM). Results: According to the TEM results, the synthesized CAS-AuNPs had a spherical shape with an average size of 20 nm. The Zeta potential of CAS-AuNPs was -38.2 mV. Statistical analyses showed that CAS-AuNPs could significantly reduce the minimum inhibitory concentration against C. albicans (P=0.0005) and non-albicans Candida (NAC) species (P<0.0001). All isolates had a MIC value of ≥ 4 µg/ml for CAS, except for C. glabrata. The results of SEM analysis confirmed the effects of AuNPs on the membrane and cell wall structure of C. globrata exposed to CAS-AuNPs, facilitating the formation of pores on the cell wall and finally cell death. Conclusion: The findings revealed that CAS-AuNPs conjugates had significant antifungal effects against Candida spp. through the degradation of the membrane and cell wall integrity. Therefore, it can be concluded that the encapsulation of antifungal drugs in combination with NPs not only diminishes side effects but also enhances the effectiveness of the medications.

scholarly journals Deletion ofADA2Increases Antifungal Drug Susceptibility and Virulence inCandida glabrata

2018 ◽  
Vol 62 (3) ◽  
Author(s):  
Shang-Jie Yu ◽  
Ya-Lin Chang ◽  
Ying-Lien Chen
Keyword(s):  
Cell Wall ◽  
Systemic Infection ◽  
Drug Tolerance ◽  
Drug Susceptibility ◽  
Antifungal Drugs ◽  
Antifungal Drug ◽  
Saga Complex ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Downstream Target

ABSTRACTCandida glabrata, the second most frequent cause of candidiasis afterCandida albicans, is an emerging human fungal pathogen that is intrinsically drug tolerant. Currently, studies ofC. glabratagenes involved in drug tolerance are limited. Ada2, a component serving as a transcription adaptor of the Spt-Ada-Gcn5 acetyltransferase (SAGA) complex, is required for antifungal drug tolerance and virulence inC. albicans. However, its roles inC. glabrataremain elusive. In this study, we found thatada2mutants demonstrated severe growth defects at 40°C but only mild defects at 37°C or 25°C. In addition,C. glabrata ada2mutants exhibited pleiotropic phenotypes, including susceptibility to three classes of antifungal drugs (i.e., azoles, echinocandins, and polyenes) and cell wall-perturbing agents but resistance to the endoplasmic reticulum stressor tunicamycin. According to RNA sequence analysis, the expression of 43 genes was downregulated and the expression of 442 genes was upregulated in theada2mutant compared to their expression in the wild type.C. glabrata ADA2, along with its downstream targetERG6, controls antifungal drug tolerance and cell wall integrity. Surprisingly,ada2mutants were hypervirulent in a murine model of systemic infection, possibly due to the upregulation of multiple adhesin-like genes, increased agar invasion, and overstimulation of murine tumor necrosis factor alpha production.

Localisation of the Schizosaccharomyces pombe rho1p GTPase and its involvement in the organisation of the actin cytoskeleton

1997 ◽  
Vol 110 (20) ◽  
pp. 2547-2555 ◽  
Author(s):  
M. Arellano ◽  
A. Duran ◽  
P. Perez
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Schizosaccharomyces Pombe ◽  
Antifungal Drugs ◽  
Dominant Negative ◽  
Cortical Actin ◽  
Glucan Synthase ◽  
Cell Wall Growth ◽  
Wall Growth ◽  
Mutant Cells

The Schizosaccharomyces pombe rho1p GTPase directly activates the (1–3) beta-D-glucan synthase and participates in the regulation of cell wall growth and morphogenesis in this fission yeast. Indirect immunofluorescence experiments using rho1p tagged with hemagglutinin have revealed that rho1p was located at the growing tips during interphase and at the septum prior to cytokinesis, localising to the same areas as actin patches. In S. pombe cdc10-129 mutant cells, arrested in G1, HA-rho1p accumulates at one tip whereas in cdc25-22 mutants, arrested in G2, HA-rho1p accumulates at both tips. In tea1-1 and tea2-1 cdc11-119 mutant cells, HA-rho1p is localised to the new growing tips. Overexpression of different rho1 mutant alleles caused different effects on cortical actin patch distribution, (1–3) beta-D-glucan synthase activation, and sensitivity to cell wall specific antifungal drugs. These results indicate that multiple cellular components are activated by rho1p. Overexpression of the dominant negative rho1T20N allele was lethal as was the rho1+ deletion. Moreover, when rho1+ expression was repressed in actively growing S. pombe, cells died in about 10 to 12 hours. Under these conditions, normal cell morphology was maintained but the level of (1–3) beta-D-glucan synthase activity decreased and the actin patches disappeared. Most cells lysed after cytokinesis during the process of separation, and lysis was not prevented by an osmotic stabiliser. We conclude that rho1p localisation is restricted to growth areas and regulated during the cell cycle and that rho1p is involved in cell wall growth and actin cytoskeleton organisation in S. pombe.

scholarly journals Targeting a critical step in fungal hexosamine biosynthesis

2020 ◽  
Vol 295 (26) ◽  
pp. 8678-8691 ◽  
Author(s):  
Deborah E. A. Lockhart ◽  
Mathew Stanley ◽  
Olawale G. Raimi ◽  
David A. Robinson ◽  
Dominika Boldovjakova ◽  
...  
Keyword(s):  
Cell Wall ◽  
Antifungal Drugs ◽  
Fungal Cell Wall ◽  
Fungal Cell ◽  
Hexosamine Biosynthetic Pathway ◽  
Hexosamine Biosynthesis ◽  
Key Enzyme ◽  
Opportunistic Fungal Pathogen ◽  
Extracellular Environment ◽  
Chemical Evidence

Aspergillus fumigatus is a human opportunistic fungal pathogen whose cell wall protects it from the extracellular environment including host defenses. Chitin, an essential component of the fungal cell wall, is synthesized from UDP-GlcNAc produced in the hexosamine biosynthetic pathway. As this pathway is critical for fungal cell wall integrity, the hexosamine biosynthesis enzymes represent potential targets of antifungal drugs. Here, we provide genetic and chemical evidence that glucosamine 6-phosphate N-acetyltransferase (Gna1), a key enzyme in this pathway, is an exploitable antifungal drug target. GNA1 deletion resulted in loss of fungal viability and disruption of the cell wall, phenotypes that could be rescued by exogenous GlcNAc, the product of the Gna1 enzyme. In a murine model of aspergillosis, the Δgna1 mutant strain exhibited attenuated virulence. Using a fragment-based approach, we discovered a small heterocyclic scaffold that binds proximal to the Gna1 active site and can be optimized to a selective submicromolar binder. Taken together, we have provided genetic, structural, and chemical evidence that Gna1 is an antifungal target in A. fumigatus.

scholarly journals Novel tool to quantify cell wall porosity relates wall structure to cell growth and drug uptake

2019 ◽  
Vol 218 (4) ◽  
pp. 1408-1421 ◽  
Author(s):  
Xiaohui Liu ◽  
Jiazhou Li ◽  
Heyu Zhao ◽  
Boyang Liu ◽  
Thomas Günther-Pomorski ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Dynamic Structure ◽  
Cell Types ◽  
Antifungal Drugs ◽  
Drug Uptake ◽  
Wall Structure ◽  
Quenching Efficiency ◽  
Model Plant Arabidopsis Thaliana ◽  
Cell Wall Porosity

Even though cell walls have essential functions for bacteria, fungi, and plants, tools to investigate their dynamic structure in living cells have been missing. Here, it is shown that changes in the intensity of the plasma membrane dye FM4-64 in response to extracellular quenchers depend on the nano-scale porosity of cell walls. The correlation of quenching efficiency and cell wall porosity is supported by tests on various cell types, application of differently sized quenchers, and comparison of results with confocal, electron, and atomic force microscopy images. The quenching assay was used to investigate how changes in cell wall porosity affect the capability for extension growth in the model plant Arabidopsis thaliana. Results suggest that increased porosity is not a precondition but a result of cell extension, thereby providing new insight on the mechanism plant organ growth. Furthermore, it was shown that higher cell wall porosity can facilitate the action of antifungal drugs in Saccharomyces cerevisiae, presumably by facilitating uptake.

scholarly journals Evaluation of Antifungal Activity and Mode of Action of New Coumarin Derivative, 7-Hydroxy-6-nitro-2H-1-benzopyran-2-one, againstAspergillusspp.

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Felipe Queiroga Sarmento Guerra ◽  
Rodrigo Santos Aquino de Araújo ◽  
Janiere Pereira de Sousa ◽  
Fillipe de Oliveira Pereira ◽  
Francisco J. B. Mendonça-Junior ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mode Of Action ◽  
Cell Walls ◽  
Coumarin Derivative ◽  
Antifungal Drugs ◽  
Azole Resistance ◽  
Subinhibitory Concentration ◽  
Fungal Cell ◽  
Mycelia Growth

Aspergillusspp. produce a wide variety of diseases. For the treatment of such infections, the azoles and Amphotericin B are used in various formulations. The treatment of fungal diseases is often ineffective, because of increases in azole resistance and their several associated adverse effects. To overcome these problems, natural products and their derivatives are interesting alternatives. The aim of this study was to examine the effects of coumarin derivative, 7-hydroxy-6-nitro-2H-1-benzopyran-2-one (Cou-NO2), both alone and with antifungal drugs. Its mode of action againstAspergillusspp. Cou-NO2was tested to evaluate its effects on mycelia growth and germination of fungal conidia ofAspergillusspp. We also investigated possible Cou-NO2action on cell walls (0.8 M sorbitol) and on Cou-NO2to ergosterol binding in the cell membrane. The study shows that Cou-NO2is capable of inhibiting both the mycelia growth and germination of conidia for the species tested, and that its action affects the structure of the fungal cell wall. At subinhibitory concentration, Cou-NO2enhanced thein vitroeffects of azoles. Moreover, in combination with azoles (voriconazole and itraconazole) Cou-NO2displays an additive effect. Thus, our study supports the use of coumarin derivative 7-hydroxy-6-nitro-2H-1-benzopyran-2-one as an antifungal agent againstAspergillusspecies.

scholarly journals Mitogen-Activated Protein Kinase Cross-Talk Interaction Modulates the Production of Melanins in Aspergillus fumigatus

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Adriana Oliveira Manfiolli ◽  
Filipe Silva Siqueira ◽  
Thaila Fernanda dos Reis ◽  
Patrick Van Dijck ◽  
Sanne Schrevens ◽  
...  
Keyword(s):  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Cross Talk ◽  
Pathogenic Fungus ◽  
Antifungal Drugs ◽  
Mitogen Activated Protein Kinase ◽  
Melanin Production ◽  
Content Type ◽  
Mitogen Activated Protein ◽  
Salvage Pathways

ABSTRACT The pathogenic fungus Aspergillus fumigatus is able to adapt to extremely variable environmental conditions. The A. fumigatus genome contains four genes coding for mitogen-activated protein kinases (MAPKs), which are important regulatory knots involved in diverse cellular responses. From a clinical perspective, MAPK activity has been connected to salvage pathways, which can determine the failure of effective treatment of invasive mycoses using antifungal drugs. Here, we report the characterization of the Saccharomyces cerevisiae Fus3 ortholog in A. fumigatus, designated MpkB. We demonstrate that MpkB is important for conidiation and that its deletion induces a copious increase of dihydroxynaphthalene (DHN)-melanin production. Simultaneous deletion of mpkB and mpkA, the latter related to maintenance of the cell wall integrity, normalized DHN-melanin production. Localization studies revealed that MpkB translocates into the nuclei when A. fumigatus germlings are exposed to caspofungin stress, and this is dependent on the cross-talk interaction with MpkA. Additionally, DHN-melanin formation was also increased after deletion of genes coding for the Gα protein GpaA and for the G protein-coupled receptor GprM. Yeast two-hybrid and coimmunoprecipitation assays confirmed that GpaA and GprM interact, suggesting their role in the MpkB signaling cascade. IMPORTANCE Aspergillus fumigatus is the most important airborne human pathogenic fungus, causing thousands of deaths per year. Its lethality is due to late and often inaccurate diagnosis and the lack of efficient therapeutics. The failure of efficient prophylaxis and therapy is based on the ability of this pathogen to activate numerous salvage pathways that are capable of overcoming the different drug-derived stresses. A major role in the protection of A. fumigatus is played by melanins. Melanins are cell wall-associated macromolecules classified as virulence determinants. The understanding of the various signaling pathways acting in this organism can be used to elucidate the mechanism beyond melanin production and help to identify ideal drug targets.

scholarly journals Up against the Wall: Is Yeast Cell Wall Integrity Ensured by Mechanosensing in Plasma Membrane Microdomains?

2014 ◽  
Vol 81 (3) ◽  
pp. 806-811 ◽  
Author(s):  
Christian Kock ◽  
Yves F. Dufrêne ◽  
Jürgen J. Heinisch
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Yeast Cell ◽  
Antifungal Drugs ◽  
Cell Wall Integrity ◽  
Yeast Cell Wall ◽  
Membrane Microdomains ◽  
Wall Structure ◽  
Fungal Cell ◽  
Membrane Spanning

ABSTRACTYeast cell wall integrity (CWI) signaling serves as a model of the regulation of fungal cell wall synthesis and provides the basis for the development of antifungal drugs. A set of five membrane-spanning sensors (Wsc1 to Wsc3, Mid2, and Mtl1) detect cell surface stress and commence the signaling pathway upon perturbations of either the cell wall structure or the plasma membrane. We here summarize the latest advances in the structure/function relationship primarily of the Wsc1 sensor and critically review the evidence that it acts as a mechanosensor. The relevance and physiological significance of the information obtained for the function of the other CWI sensors, as well as expected future developments, are discussed.

scholarly journals UDP-4-Keto-6-Deoxyglucose, a Transient Antifungal Metabolite, Weakens the Fungal Cell Wall Partly by Inhibition of UDP-Galactopyranose Mutase

mBio ◽  
2017 ◽  
Vol 8 (6) ◽  
Author(s):  
Liang Ma ◽  
Omar Salas ◽  
Kyle Bowler ◽  
Maor Bar-Peled ◽  
Amir Sharon
Keyword(s):  
Cell Wall ◽  
Structural Similarity ◽  
Intermediate Compound ◽  
Antifungal Drugs ◽  
Nucleotide Sugar ◽  
Undetermined Function ◽  
Nucleotide Sugars ◽  
Toxic Potential ◽  
Additional Nucleotide ◽  
Surprising Finding

ABSTRACT Can accumulation of a normally transient metabolite affect fungal biology? UDP-4-keto-6-deoxyglucose (UDP-KDG) represents an intermediate stage in conversion of UDP-glucose to UDP-rhamnose. Normally, UDP-KDG is not detected in living cells, because it is quickly converted to UDP-rhamnose by the enzyme UDP-4-keto-6-deoxyglucose-3,5-epimerase/-4-reductase (ER). We previously found that deletion of the er gene in Botrytis cinerea resulted in accumulation of UDP-KDG to levels that were toxic to the fungus due to destabilization of the cell wall. Here we show that these negative effects are at least partly due to inhibition by UDP-KDG of the enzyme UDP-galactopyranose mutase (UGM), which reversibly converts UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf). An enzymatic activity assay showed that UDP-KDG inhibits the B. cinerea UGM enzyme with a K i of 221.9 µM. Deletion of the ugm gene resulted in strains with weakened cell walls and phenotypes that were similar to those of the er deletion strain, which accumulates UDP-KDG. Galf residue levels were completely abolished in the Δugm strain and reduced in the Δer strain, while overexpression of the ugm gene in the background of a Δer strain restored Galf levels and alleviated the phenotypes. Collectively, our results show that the antifungal activity of UDP-KDG is due to inhibition of UGM and possibly other nucleotide sugar-modifying enzymes and that the rhamnose metabolic pathway serves as a shunt that prevents accumulation of UDP-KDG to toxic levels. These findings, together with the fact that there is no Galf in mammals, support the possibility of developing UDP-KDG or its derivatives as antifungal drugs. IMPORTANCE Nucleotide sugars are donors for the sugars in fungal wall polymers. We showed that production of the minor sugar rhamnose is used primarily to neutralize the toxic intermediate compound UDP-KDG. This surprising finding highlights a completely new role for minor sugars and other secondary metabolites with undetermined function. Furthermore, the toxic potential of predicted transition metabolites that never accumulate in cells under natural conditions are highlighted. We demonstrate that UDP-KDG inhibits the UDP-galactopyranose mutase enzyme, thereby affecting production of Galf, which is one of the components of cell wall glycans. Given the structural similarity, UDP-KDG likely inhibits additional nucleotide sugar-utilizing enzymes, a hypothesis that is also supported by our findings. Our results suggest that UDP-KDG could serve as a template to develop antifungal drugs. IMPORTANCE Nucleotide sugars are donors for the sugars in fungal wall polymers. We showed that production of the minor sugar rhamnose is used primarily to neutralize the toxic intermediate compound UDP-KDG. This surprising finding highlights a completely new role for minor sugars and other secondary metabolites with undetermined function. Furthermore, the toxic potential of predicted transition metabolites that never accumulate in cells under natural conditions are highlighted. We demonstrate that UDP-KDG inhibits the UDP-galactopyranose mutase enzyme, thereby affecting production of Galf, which is one of the components of cell wall glycans. Given the structural similarity, UDP-KDG likely inhibits additional nucleotide sugar-utilizing enzymes, a hypothesis that is also supported by our findings. Our results suggest that UDP-KDG could serve as a template to develop antifungal drugs.

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