Tunicamycin Potentiates Antifungal Drug Tolerance via Aneuploidy in Candida albicans

Candida albicans is a prevalent human fungal commensal and also a pathogen that causes life-threatening systemic infections. Treatment failures are frequent because few therapeutic antifungal drug classes are available and because drug resistance and tolerance limit drug efficacy.

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Role of Matrix β-1,3 Glucan in Antifungal Resistance of Non-albicans Candida Biofilms

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02378-12 ◽

2013 ◽

Vol 57 (4) ◽

pp. 1918-1920 ◽

Cited By ~ 68

Author(s):

K. F. Mitchell ◽

H. T. Taff ◽

M. A. Cuevas ◽

E. L. Reinicke ◽

H. Sanchez ◽

...

Keyword(s):

Health Care ◽

Drug Resistance ◽

Candida Albicans ◽

Care Setting ◽

Antifungal Susceptibility ◽

Antifungal Drug ◽

Content Type ◽

The Matrix ◽

Biofilm Matrix

ABSTRACTCandidabiofilm infections pose an increasing threat in the health care setting due to the drug resistance associated with this lifestyle. Several mechanisms underlie the resistance phenomenon. InCandida albicans, one mechanism involves drug impedance by the biofilm matrix linked to β-1,3 glucan. Here, we show this is important for otherCandidaspp. We identified β-1,3 glucan in the matrix, found that the matrix sequesters antifungal drug, and enhanced antifungal susceptibility with matrix β-1,3 glucan hydrolysis.

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The SUMO protease Ulp2 regulates genome stability and drug resistance in the human fungal pathogen Candida albicans

10.1101/2021.12.06.471441 ◽

2021 ◽

Author(s):

Marzia Rizzo ◽

Natthapon Soisangwan ◽

Jan Soetaert ◽

Samuel Vega-Estevez ◽

Anna Selmecki ◽

...

Keyword(s):

Drug Resistance ◽

Candida Albicans ◽

Fungal Pathogen ◽

Genome Instability ◽

Antifungal Drugs ◽

Antifungal Drug ◽

Genome Plasticity ◽

Sumo Protease ◽

Human Fungal Pathogen ◽

Life Threatening

AbstractStress-induced genome instability in microbial organisms is emerging as a critical regulatory mechanism for driving rapid and reversible adaption to drastic environmental changes. In Candida albicans, a human fungal pathogen that causes life-threatening infections, genome plasticity confers increased virulence and antifungal drug resistance. Discovering the mechanisms regulating C. albicans genome plasticity is a priority to understand how this and other microbial pathogens establish life-threatening infections and develop resistance to antifungal drugs. We identified the SUMO protease Ulp2 as a critical regulator of C. albicans genome integrity through genetic screening. Deletion of ULP2 leads to hypersensitivity to genotoxic agents and increased genome instability. This increased genome diversity causes reduced fitness under standard laboratory growth conditions but enhances adaptation to stress, making ulp2Δ/Δ cells more likely to thrive in the presence of antifungal drugs. Whole-genome sequencing indicates that ulp2Δ/Δ cells counteract antifungal drug-induced stress by developing segmental aneuploidies of chromosome R and chromosome I. We demonstrate that intrachromosomal repetitive elements drive the formation of complex novel genotypes with adaptive power.

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Large-Scale Biochemical Profiling of the Candida albicans Biofilm Matrix: New Compositional, Structural, and Functional Insights

mBio ◽

10.1128/mbio.01781-14 ◽

2014 ◽

Vol 5 (5) ◽

Cited By ~ 15

Author(s):

Jose L. Lopez-Ribot

Keyword(s):

Drug Resistance ◽

Candida Albicans ◽

Large Scale ◽

Pathogenic Fungi ◽

Antifungal Drug ◽

Content Type ◽

Antifungal Drug Resistance ◽

Functional Aspects ◽

Main Components ◽

Biofilm Matrix

ABSTRACTAmong pathogenic fungi,Candida albicansis most frequently associated with biofilm formation, a lifestyle that is entirely different from the planktonic state. One of the distinguishing features of these biofilms is the presence of extracellular material, commonly referred to as the “biofilm matrix.” The fungal biofilm matrix embeds sessile cells within these communities and plays important structural and physiological functions, including antifungal drug resistance with important clinical repercussions. This matrix is mostly self-produced by the fungal cells themselves and is composed of different types of biopolymers. InC. albicans, the main components of the biofilm matrix are carbohydrates, proteins, lipids, and DNA, but many of them remain unidentified and/or poorly characterized. In their recent article, Zarnowski et al. [mBio 5(4):e01333-14, 2014, doi:10.1128/mBio.01333-14] used a variety of biochemical and state-of-the-art “omic” approaches (glycomics, proteomics, and lipidomics) to identify and characterize unique biopolymers present in theC. albicansbiofilm matrix. Besides generating a true “encyclopedic” catalog of individual moieties from each of the different macromolecular categories, results also provide important insights into structural and functional aspects of the fungal biofilm matrix, particularly the interaction between different components and the contribution of multiple matrix constituents to biofilm antifungal drug resistance.

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Engineering a Cysteine-Deficient Functional Candida albicans Cdr1 Molecule Reveals a Conserved Region at the Cytosolic Apex of ABCG Transporters Important for Correct Folding and Trafficking of Cdr1

mSphere ◽

10.1128/msphere.01318-20 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Golnoush Madani ◽

Erwin Lamping ◽

Richard D. Cannon

Keyword(s):

Drug Resistance ◽

Candida Albicans ◽

Pleiotropic Drug Resistance ◽

Content Type ◽

Antifungal Drug Resistance ◽

Transporter Family ◽

Invasive Infections ◽

Life Threatening ◽

And Function

ABSTRACT Pleiotropic drug resistance (PDR) ATP-binding cassette (ABC) transporters of the ABCG family are eukaryotic membrane proteins that pump an array of compounds across organelle and cell membranes. Overexpression of the archetype fungal PDR transporter Cdr1 is a major cause of azole antifungal drug resistance in Candida albicans, a significant fungal pathogen that can cause life-threatening invasive infections in immunocompromised individuals. To date, no structure for any PDR transporter has been solved. The objective of this project was to investigate the role of the 23 Cdr1 cysteine residues in the stability, trafficking, and function of the protein when expressed in the eukaryotic model organism, Saccharomyces cerevisiae. The biochemical characterization of 18 partially cysteine-deficient Cdr1 variants revealed that the six conserved extracellular cysteines were critical for proper expression, localization, and function of Cdr1. They are predicted to form three covalent disulfide bonds that stabilize the large extracellular domains of fungal PDR transporters. Our investigations also revealed a novel nucleotide-binding domain motif, GX2[3]CPX3NPAD/E, at the peripheral cytosolic apex of ABCG transporters that possibly contributes to the unique ABCG transport cycle. With this knowledge, we engineered an “almost cysteine-less,” yet fully functional, Cdr1 variant, Cdr1P-CID, that had all but the six extracellular cysteines replaced with serine, alanine, or isoleucine (C1106I of the new motif). It is now possible to perform cysteine-cross-linking studies that will enable more detailed biochemical investigations of fungal PDR transporters and confirm any future structure(s) solved for this important protein family. IMPORTANCE Overexpression of the fungal pleiotropic drug resistance (PDR) transporter Cdr1 is a major cause of antifungal drug resistance in Candida albicans, a significant fungal pathogen that can cause life-threatening invasive infections in immunocompromised individuals. To date, no structure for any PDR ABC transporter has been solved. Cdr1 contains 23 cysteines; 10 are cytosolic and 13 are predicted to be in the transmembrane or the extracellular domains. The objective of this project was to create, and biochemically characterize, CDR1 mutants to reveal which cysteines are most important for Cdr1 stability, trafficking, and function. During this process we discovered a novel motif at the cytosolic apex of PDR transporters that ensures the structural and functional integrity of the ABCG transporter family. The creation of a functional Cys-deficient Cdr1 molecule opens new avenues for cysteine-cross-linking studies that will facilitate the detailed characterization of an important ABCG transporter family member.

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The Chemistry of Drugs to Treat Candida albicans

Current Topics in Medicinal Chemistry ◽

10.2174/1568026619666191025153124 ◽

2019 ◽

Vol 19 (28) ◽

pp. 2554-2566 ◽

Cited By ~ 2

Author(s):

Aurelio Ortiz ◽

Estibaliz Sansinenea

Keyword(s):

Candida Species ◽

Antifungal Drugs ◽

New Drugs ◽

Drug Classes ◽

Life Threatening ◽

Antifungal Substances ◽

High Level ◽

Systemic Infections ◽

New Compounds ◽

Level Resistance

Background:: Candida species are in various parts of the human body as commensals. However, they can cause local mucosal infections and, sometimes, systemic infections in which Candida species can spread to all major organs and colonize them. Objective:: For the effective treatment of the mucosal infections and systemic life-threatening fungal diseases, a considerably large number of antifungal drugs have been developed and used for clinical purposes that comprise agents from four main drug classes: the polyenes, azoles, echinocandins, and antimetabolites. Method: : The synthesis of some of these drugs is available, allowing synthetic modification of the molecules to improve the biological activity against Candida species. The synthetic methodology for each compound is reviewed. Results: : The use of these compounds has caused a high-level resistance against these drugs, and therefore, new antifungal substances have been described in the last years. The organic synthesis of the known and new compounds is reported. Conclusion: : This article summarizes the chemistry of the existing agents, both the old drugs and new drugs, in the treatment of infections due to C. albicans, including the synthesis of the existing drugs.

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Dectin-2-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽

10.1128/msphere.00715-19 ◽

2019 ◽

Vol 4 (5) ◽

Cited By ~ 1

Author(s):

Suresh Ambati ◽

Emma C. Ellis ◽

Jianfeng Lin ◽

Xiaorong Lin ◽

Zachary A. Lewis ◽

...

Keyword(s):

Candida Albicans ◽

Aspergillus Fumigatus ◽

Effective Dose ◽

Cryptococcus Neoformans ◽

Amphotericin B ◽

Antifungal Drugs ◽

Extracellular Matrices ◽

Content Type ◽

Order Of Magnitude ◽

Life Threatening

ABSTRACT Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus cause life-threatening candidiasis, cryptococcosis, and aspergillosis, resulting in several hundred thousand deaths annually. The patients at the greatest risk of developing these life-threatening invasive fungal infections have weakened immune systems. The vulnerable population is increasing due to rising numbers of immunocompromised individuals as a result of HIV infection or immunosuppressed individuals receiving anticancer therapies and/or stem cell or organ transplants. While patients are treated with antifungals such as amphotericin B, all antifungals have serious limitations due to lack of sufficient fungicidal effect and/or host toxicity. Even with treatment, 1-year survival rates are low. We explored methods of increasing drug effectiveness by designing fungicide-loaded liposomes specifically targeted to fungal cells. Most pathogenic fungi are encased in cell walls and exopolysaccharide matrices rich in mannans. Dectin-2 is a mammalian innate immune membrane receptor that binds as a dimer to mannans and signals fungal infection. We coated amphotericin-loaded liposomes with monomers of Dectin-2’s mannan-binding domain, sDectin-2. sDectin monomers were free to float in the lipid membrane and form dimers that bind mannan substrates. sDectin-2-coated liposomes bound orders of magnitude more efficiently to the extracellular matrices of several developmental stages of C. albicans, C. neoformans, and A. fumigatus than untargeted control liposomes. Dectin-2-coated amphotericin B-loaded liposomes reduced the growth and viability of all three species more than an order of magnitude more efficiently than untargeted control liposomes and dramatically decreased the effective dose. Future efforts focus on examining pan-antifungal targeted liposomal drugs in animal models of fungal diseases. IMPORTANCE Invasive fungal diseases caused by Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus have mortality rates ranging from 10 to 95%. Individual patient costs may exceed $100,000 in the United States. All antifungals in current use have serious limitations due to host toxicity and/or insufficient fungal cell killing that results in recurrent infections. Few new antifungal drugs have been introduced in the last 2 decades. Hence, there is a critical need for improved antifungal therapeutics. By targeting antifungal-loaded liposomes to α-mannans in the extracellular matrices secreted by these fungi, we dramatically reduced the effective dose of drug. Dectin-2-coated liposomes loaded with amphotericin B bound 50- to 150-fold more strongly to C. albicans, C. neoformans, and A. fumigatus than untargeted liposomes and killed these fungi more than an order of magnitude more efficiently. Targeting drug-loaded liposomes specifically to fungal cells has the potential to greatly enhance the efficacy of most antifungal drugs.

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The Early Transcriptional Response of Human Granulocytes to Infection with Candida albicans Is Not Essential for Killing but Reflects Cellular Communications

Infection and Immunity ◽

10.1128/iai.01651-06 ◽

2006 ◽

Vol 75 (3) ◽

pp. 1493-1501 ◽

Cited By ~ 28

Author(s):

Chantal Fradin ◽

Abigail L. Mavor ◽

Günther Weindl ◽

Martin Schaller ◽

Karin Hanke ◽

...

Keyword(s):

Candida Albicans ◽

Mononuclear Cells ◽

De Novo ◽

Transcriptional Response ◽

Mononuclear Leukocytes ◽

General Notion ◽

Genes Encoding ◽

Global Transcriptional Profile ◽

Life Threatening ◽

Systemic Infections

ABSTRACT Candida albicans is a polymorphic opportunistic fungus that can cause life-threatening systemic infections following hematogenous dissemination in patients susceptible to nosocomial infection. Neutrophils form part of the innate immune response, which is the first line of defense against microbes and is particularly important in C. albicans infections. To compare the transcriptional response of leukocytes exposed to C. albicans, we investigated the expression of key cytokine genes in polymorphonuclear and mononuclear leukocytes after incubation with C. albicans for 1 h. Isolated mononuclear cells expressed high levels of genes encoding proinflammatory signaling molecules, whereas neutrophils exhibited much lower levels, similar to those observed in whole blood. The global transcriptional profile of neutrophils was examined by using an immunology-biased human microarray to determine whether different morphological forms or the viability of C. albicans altered the transcriptome. Hyphal cells appeared to have the broadest effect, although the most strongly induced genes were regulated independently of morphology or viability. These genes were involved in proinflammatory cell-cell signaling, cell signal transduction, and cell growth. Generally, genes encoding known components of neutrophil granules showed no upregulation at this time point; however, lactoferrin, a well-known candidacidal peptide, was secreted by neutrophils. Addition to inhibitors of RNA or protein de novo synthesis did not influence the killing activity within 30 min. These results support the general notion that neutrophils do not require gene transcription to mount an immediate and direct attack against microbes. However, neutrophils exposed to C. albicans express genes involved in communication with other immune cells.

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Environmental Isolates of Azole-Resistant Aspergillus fumigatus in Germany

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00100-15 ◽

2015 ◽

Vol 59 (7) ◽

pp. 4356-4359 ◽

Cited By ~ 59

Author(s):

Oliver Bader ◽

Jana Tünnermann ◽

Anna Dudakova ◽

Marut Tangwattanachuleeporn ◽

Michael Weig ◽

...

Keyword(s):

Drug Resistance ◽

Aspergillus Fumigatus ◽

Antifungal Drug ◽

Clinical Samples ◽

Environmental Isolates ◽

Northern Germany ◽

Content Type ◽

Antifungal Drug Resistance ◽

The World

ABSTRACTAzole antifungal drug resistance inAspergillus fumigatusis an emerging problem in several parts of the world. Here we investigated the distribution of such strains in soils from Germany. At a general positivity rate of 12%, most prevalently, we found strains with the TR34/L98H and TR46/Y121F/T289A alleles, dispersed along a corridor across northern Germany. Comparison of the distributions of resistance alleles and genotypes between environment and clinical samples suggests the presence of local clinical clusters.

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Deletion ofADA2Increases Antifungal Drug Susceptibility and Virulence inCandida glabrata

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01924-17 ◽

2018 ◽

Vol 62 (3) ◽

Cited By ~ 12

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.

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Dysfunction of Prohibitin 2 Results in Reduced Susceptibility to Multiple Antifungal Drugs via Activation of the Oxidative Stress-Responsive Transcription Factor Pap1 in Fission Yeast

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00860-18 ◽

2018 ◽

Vol 62 (11) ◽

Cited By ~ 1

Author(s):

Qiannan Liu ◽

Fan Yao ◽

Guanglie Jiang ◽

Min Xu ◽

Si Chen ◽

...

Keyword(s):

Oxidative Stress ◽

Drug Resistance ◽

Transcription Factor ◽

Fission Yeast ◽

Mitochondrial Protein ◽

Antifungal Drugs ◽

Antifungal Drug ◽

Gene Encoding ◽

Content Type ◽

Antifungal Drug Resistance

ABSTRACT The fight against resistance to antifungal drugs requires a better understanding of the underlying cellular mechanisms. In order to gain insight into the mechanisms leading to antifungal drug resistance, we performed a genetic screen on a model organism, Schizosaccharomyces pombe, to identify genes whose overexpression caused resistance to antifungal drugs, including clotrimazole and terbinafine. We identified the phb2+ gene, encoding a highly conserved mitochondrial protein, prohibitin (Phb2), as a novel determinant of reduced susceptibility to multiple antifungal drugs. Unexpectedly, deletion of the phb2+ gene also exhibited antifungal drug resistance. Overexpression of the phb2+ gene failed to cause drug resistance when the pap1+ gene, encoding an oxidative stress-responsive transcription factor, was deleted. Furthermore, pap1+ mRNA expression was significantly increased when the phb2+ gene was overexpressed or deleted. Importantly, either overexpression or deletion of the phb2+ gene stimulated the synthesis of NO and reactive oxygen species (ROS), as measured by the cell-permeant fluorescent NO probe DAF-FM DA (4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate) and the ROS probe DCFH-DA (2′,7′-dichlorodihydrofluorescein diacetate), respectively. Taken together, these results suggest that Phb2 dysfunction results in reduced susceptibility to multiple antifungal drugs by increasing NO and ROS synthesis due to dysfunctional mitochondria, thereby activating the transcription factor Pap1 in fission yeast.

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