scholarly journals MIG1Regulates Resistance of Candida albicans against the Fungistatic Effect of Weak Organic Acids

2015 ◽  
Vol 14 (10) ◽  
pp. 1054-1061 ◽  
Author(s):  
Fabien Cottier ◽  
Alrina Shin Min Tan ◽  
Xiaoli Xu ◽  
Yue Wang ◽  
Norman Pavelka
Keyword(s):  
Candida Albicans ◽  
Organic Acids ◽  
Fungal Infections ◽  
Glucose Repression ◽  
Single Gene ◽  
Human Microbiome ◽  
Fungal Resistance ◽  
Content Type ◽  
Weak Organic Acids ◽  
Fungistatic Effect

ABSTRACTCandida albicansis the leading cause of fungal infections; but it is also a member of the human microbiome, an ecosystem of thousands of microbial species potentially influencing the outcome of host-fungal interactions. Accordingly, antibacterial therapy raises the risk of candidiasis, yet the underlying mechanism is currently not fully understood. We hypothesize the existence of bacterial metabolites that normally controlC. albicansgrowth and of fungal resistance mechanisms against these metabolites. Among the most abundant microbiota-derived metabolites found on human mucosal surfaces are weak organic acids (WOAs), such as acetic, propionic, butyric, and lactic acid. Here, we used quantitative growth assays to investigate the dose-dependent fungistatic properties of WOAs onC. albicansgrowth and found inhibition of growth to occur at physiologically relevant concentrations and pH values. This effect was conserved across distantly related fungal species both inside and outside the CTG clade. We next screened a library of transcription factor mutants and identified several genes required for the resistance ofC. albicansto one or more WOAs. A single gene,MIG1, previously known for its role in glucose repression, conferred resistance against all four acids tested. Consistent with glucose being an upstream activator of Mig1p, the presence of this carbon source was required for WOA resistance in wild-typeC. albicans. Conversely, aMIG1-complemented strain completely restored the glucose-dependent resistance against WOAs. We conclude that Mig1p plays a central role in orchestrating a transcriptional program to fight against the fungistatic effect of this class of highly abundant metabolites produced by the gastrointestinal tract microbiota.

scholarly journals Acylhydrazones as Antifungal Agents Targeting the Synthesis of Fungal Sphingolipids

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Cristina Lazzarini ◽  
Krupanandan Haranahalli ◽  
Robert Rieger ◽  
Hari Krishna Ananthula ◽  
Pankaj B. Desai ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
Antifungal Drugs ◽  
Fungal Resistance ◽  
Content Type ◽  
Highly Active ◽  
Pharmacokinetic Properties ◽  
Pass Through

ABSTRACTThe incidence of invasive fungal infections has risen dramatically in recent decades. Current antifungal drugs are either toxic, likely to interact with other drugs, have a narrow spectrum of activity, or induce fungal resistance. Hence, there is a great need for new antifungals, possibly with novel mechanisms of action. Previously our group reported an acylhydrazone called BHBM that targeted the sphingolipid pathway and showed strong antifungal activity against several fungi. In this study, we screened 19 derivatives of BHBM. Three out of 19 derivatives were highly active againstCryptococcus neoformansin vitroand had low toxicity in mammalian cells. In particular, one of them, called D13, had a high selectivity index and showed better activity in an animal model of cryptococcosis, candidiasis, and pulmonary aspergillosis. D13 also displayed suitable pharmacokinetic properties and was able to pass through the blood-brain barrier. These results suggest that acylhydrazones are promising molecules for the research and development of new antifungal agents.

scholarly journals Intravital Imaging of Candida albicans Identifies Differential In Vitro and In Vivo Filamentation Phenotypes for Transcription Factor Deletion Mutants

mSphere ◽  
2021 ◽  
Author(s):  
Rohan S. Wakade ◽  
Manning Huang ◽  
Aaron P. Mitchell ◽  
Melanie Wellington ◽  
Damian J. Krysan
Keyword(s):  
Candida Albicans ◽  
Fungal Infections ◽  
Deletion Mutants ◽  
Filamentous Form ◽  
Content Type ◽  
Yeast Form ◽  
Common Causes ◽  
Do So

Candida albicans is one of the most common causes of fungal infections in humans. C. albicans undergoes a transition from a round yeast form to a filamentous form during infection, which is critical for its ability to cause disease. Although this transition has been studied in the laboratory for years, methods to do so in an animal model of infection have been limited.

scholarly journals Clinical Candida albicans Vaginal Isolates and a Laboratory Strain Show Divergent Behaviors during Macrophage Interactions

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Franziska Gerwien ◽  
Christine Dunker ◽  
Philipp Brandt ◽  
Enrico Garbe ◽  
Ilse D. Jacobsen ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Fungal Infections ◽  
Laboratory Strain ◽  
Infection Process ◽  
Vulvovaginal Candidiasis ◽  
Host Immune System ◽  
Host Pathogen Interactions ◽  
Content Type ◽  
Host Pathogen

ABSTRACT Typically, established lab strains are widely used to study host-pathogen interactions. However, to better reflect the infection process, the experimental use of clinical isolates has come more into focus. Here, we analyzed the interaction of multiple vaginal isolates of the opportunistic fungal pathogen Candida albicans, the most common cause of vulvovaginal candidiasis in women, with key players of the host immune system: macrophages. We tested several strains isolated from asymptomatic or symptomatic women with acute and recurrent infections. While all clinical strains showed a response similar to the commonly used lab strain SC5314 in various in vitro assays, they displayed remarkable differences during interaction with macrophages. This coincided with significantly reduced β-glucan exposure on the cell surface, which appeared to be a shared property among the tested vaginal strains for yeast extract/peptone/dextrose-grown cells, which is partly lost when the isolates faced vaginal niche-like nutrient conditions. However, macrophage damage, survival of phagocytosis, and filamentation capacities were highly strain-specific. These results highlight the high heterogeneity of C. albicans strains in host-pathogen interactions, which have to be taken into account to bridge the gap between laboratory-gained data and disease-related outcomes in an actual patient. IMPORTANCE Vulvovaginal candidiasis is one of the most common fungal infections in humans with Candida albicans as the major causative agent. This study is the first to compare clinical vaginal isolates of defined patient groups in their interaction with macrophages, highlighting the vastly different outcomes in comparison to a laboratory strain using commonly applied virulence-determining assays.

scholarly journals Tolerance to Caspofungin in Candida albicans Is Associated with at Least Three Distinctive Mechanisms That Govern Expression of FKS Genes and Cell Wall Remodeling

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Feng Yang ◽  
Lulu Zhang ◽  
Hironao Wakabayashi ◽  
Jason Myers ◽  
Yuanying Jiang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fungal Infections ◽  
Direct Selection ◽  
Resistance Development ◽  
Content Type ◽  
Cellular Factors ◽  
Echinocandin Resistance ◽  
Diploid Level ◽  
The Right

ABSTRACT Expanding echinocandin use to prevent or treat invasive fungal infections has led to an increase in the number of breakthrough infections due to resistant Candida species. Although it is uncommon, echinocandin resistance is well documented for Candida albicans, which is among the most prevalent bloodstream organisms. A better understanding is needed to assess the cellular factors that promote tolerance and predispose infecting cells to clinical breakthrough. We previously showed that some mutants that were adapted to growth in the presence of toxic sorbose due to loss of one chromosome 5 (Ch5) also became more tolerant to caspofungin. We found here, following direct selection of mutants on caspofungin, that tolerance can be conferred by at least three mechanisms: (i) monosomy of Ch5, (ii) combined monosomy of the left arm and trisomy of the right arm of Ch5, and (iii) an aneuploidy-independent mechanism. Tolerant mutants possessed cell walls with elevated chitin and showed downregulation of genes involved in cell wall biosynthesis, namely, FKS, located outside Ch5, and CHT2, located on Ch5, irrespective of Ch5 ploidy. Also irrespective of Ch5 ploidy, the CNB1 and MID1 genes on Ch5, which are involved in the calcineurin signaling pathway, were expressed at the diploid level. Thus, multiple mechanisms can affect the relative expression of the aforementioned genes, controlling them in similar ways. Although breakthrough mutations in two specific regions of FKS1 have previously been associated with caspofungin resistance, we found mechanisms of caspofungin tolerance that are independent of FKS1 and thus represent an earlier event in resistance development.

scholarly journals Crystal Structures of Full-Length Lanosterol 14α-Demethylases of Prominent Fungal Pathogens Candida albicans and Candida glabrata Provide Tools for Antifungal Discovery

2018 ◽  
Vol 62 (11) ◽  
Author(s):  
Mikhail V. Keniya ◽  
Manya Sabherwal ◽  
Rajni K. Wilson ◽  
Matthew A. Woods ◽  
Alia A. Sagatova ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Crystal Structures ◽  
Candida Glabrata ◽  
Fungal Pathogens ◽  
Catalytic Domain ◽  
Fungal Infections ◽  
Binding Pocket ◽  
Full Length ◽  
Content Type ◽  
Cure Rates

ABSTRACT Targeting lanosterol 14α-demethylase (LDM) with azole drugs provides prophylaxis and treatments for superficial and disseminated fungal infections, but cure rates are not optimal for immunocompromised patients and individuals with comorbidities. The efficacy of azole drugs has also been reduced due to the emergence of drug-resistant fungal pathogens. We have addressed the need to improve the potency, spectrum, and specificity for azoles by expressing in Saccharomyces cerevisiae functional, recombinant, hexahistidine-tagged, full-length Candida albicans LDM (CaLDM6×His) and Candida glabrata LDM (CgLDM6×His) and determining their X-ray crystal structures. The crystal structures of CaLDM6×His, CgLDM6×His, and ScLDM6×His have the same fold and bind itraconazole in nearly identical conformations. The catalytic domains of the full-length LDMs have the same fold as the CaLDM6×His catalytic domain in complex with posaconazole, with minor structural differences within the ligand binding pocket. Our structures give insight into the LDM reaction mechanism and phenotypes of single-site CaLDM mutations. This study provides a practical basis for the structure-directed discovery of novel antifungals that target LDMs of fungal pathogens.

scholarly journals Design and Evaluation of Peptide Nucleic Acid Probes for Specific Identification of Candida albicans

2014 ◽  
Vol 53 (2) ◽  
pp. 511-521 ◽  
Author(s):  
Hyun-Joong Kim ◽  
Byron F. Brehm-Stecher
Keyword(s):  
Candida Albicans ◽  
Nucleic Acid ◽  
Peptide Nucleic Acid ◽  
Fungal Infections ◽  
Dna Probes ◽  
28S Rrna ◽  
Rapid Diagnostics ◽  
Discriminative Ability ◽  
Content Type ◽  
Specific Identification

Candida albicansis an important cause of systemic fungal infections, and rapid diagnostics for identifying and differentiatingC. albicansfrom otherCandidaspecies are critical for the timely application of appropriate antimicrobial therapy, improved patient outcomes, and pharmaceutical cost savings. In this work, two 28S rRNA-directed peptide nucleic acid-fluorescencein situhybridization (PNA-FISH) probes, P-Ca726 (targeting a novel region of the ribosome) and P-CalB2208 (targeting a previously reported region), were evaluated. Hybridization conditions were optimized by using both fluorescence microscopy (FM) and flow cytometry (FCM), and probes were screened for specificity and discriminative ability against a panel ofC. albicansand various nontargetCandidaspp. The performance of these PNA probes was compared quantitatively against that of DNA probes or DNA probe/helper combinations directed against the same target regions. Ratiometric analyses of FCM results indicated that both the hybridization quality and yield of the PNA probes were higher than those of the DNA probes. In FCM-based comparisons of the PNA probes, P-Ca726 was found to be highly specific, showing 2.5- to 5.5-fold-higher discriminatory power forC. albicansthan P-CalB2208. The use of formamide further improved the performance of the new probe. Our results reinforce the significant practical and diagnostic advantages of PNA probes over their DNA counterparts for FISH and indicate that P-Ca726 may be used advantageously for the rapid and specific identification ofC. albicansin clinical and related applications, especially when combined with FCM.

scholarly journals A CRISPR Interference Platform for Efficient Genetic Repression in Candida albicans

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Lauren Wensing ◽  
Jehoshua Sharma ◽  
Deeva Uthayakumar ◽  
Yannic Proteau ◽  
Alejandro Chavez ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Human Disease ◽  
Transcriptional Repression ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Content Type ◽  
Guide Rna ◽  
Crispr Interference ◽  
Functional Genomic Analysis

ABSTRACT Fungal pathogens are emerging as an important cause of human disease, and Candida albicans is among the most common causative agents of fungal infections. Studying this fungal pathogen is of the utmost importance and necessitates the development of molecular technologies to perform comprehensive genetic and functional genomic analysis. Here, we designed and developed a novel clustered regularly interspaced short palindromic repeat interference (CRISPRi) system for targeted genetic repression in C. albicans. We engineered a nuclease-dead Cas9 (dCas9) construct that, paired with a guide RNA targeted to the promoter of an endogenous gene, is capable of targeting that gene for transcriptional repression. We further optimized a favorable promoter locus to achieve repression and demonstrated that fusion of dCas9 to an Mxi1 repressor domain was able to further enhance transcriptional repression. Finally, we demonstrated the application of this CRISPRi system through genetic repression of the essential molecular chaperone HSP90. This is the first demonstration of a functional CRISPRi repression system in C. albicans, and this valuable technology will enable many future applications in this critical fungal pathogen. IMPORTANCE Fungal pathogens are an increasingly important cause of human disease and mortality, and Candida albicans is among the most common causes of fungal disease. Studying this important fungal pathogen requires a comprehensive genetic toolkit to establish how different genetic factors play roles in the biology and virulence of this pathogen. Here, we developed a CRISPR-based genetic regulation platform to achieve targeted repression of C. albicans genes. This CRISPR interference (CRISPRi) technology exploits a nuclease-dead Cas9 protein (dCas9) fused to transcriptional repressors. The dCas9 fusion proteins pair with a guide RNA to target genetic promoter regions and to repress expression from these genes. We demonstrated the functionality of this system for repression in C. albicans and show that we can apply this technology to repress essential genes. Taking the results together, this work presents a new technology for efficient genetic repression in C. albicans, with important applications for genetic analysis in this fungal pathogen.

scholarly journals Quantitative Analysis of the Modes of Growth Inhibition by Weak Organic Acids in Saccharomyces cerevisiae

2012 ◽  
Vol 78 (23) ◽  
pp. 8377-8387 ◽  
Author(s):  
Azmat Ullah ◽  
Rick Orij ◽  
Stanley Brul ◽  
Gertien J. Smits
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Organic Acids ◽  
Growth Inhibition ◽  
Organic Anion ◽  
Acid Stress ◽  
Yeast Cells ◽  
Plasma Membrane Atpase ◽  
Weak Acids ◽  
Content Type ◽  
Weak Organic Acids

ABSTRACTWeak organic acids are naturally occurring compounds that are commercially used as preservatives in the food and beverage industries. They extend the shelf life of food products by inhibiting microbial growth. There are a number of theories that explain the antifungal properties of these weak acids, but the exact mechanism is still unknown. We set out to quantitatively determine the contributions of various mechanisms of antifungal activity of these weak acids, as well as the mechanisms that yeast uses to counteract their effects. We analyzed the effects of four weak organic acids differing in lipophilicity (sorbic, benzoic, propionic, and acetic acids) on growth and intracellular pH (pHi) inSaccharomyces cerevisiae. Although lipophilicity of the acids correlated with the rate of acidification of the cytosol, our data confirmed that not initial acidification, but rather the cell's ability to restore pHi, was a determinant for growth inhibition. This pHirecovery in turn depended on the nature of the organic anion. We identified long-term acidification as the major cause of growth inhibition under acetic acid stress. Restoration of pHi, and consequently growth rate, in the presence of this weak acid required the full activity of the plasma membrane ATPase Pma1p. Surprisingly, the proposed anion export pump Pdr12p was shown to play an important role in the ability of yeast cells to restore the pHiupon lipophilic (sorbic and benzoic) acid stress, probably through a charge interaction of anion and proton transport.

scholarly journals Abolishing Cell Wall Glycosylphosphatidylinositol-Anchored Proteins in Candida albicans Enhances Recognition by Host Dectin-1

2015 ◽  
Vol 83 (7) ◽  
pp. 2694-2704 ◽  
Author(s):  
Hui Shen ◽  
Si Min Chen ◽  
Wei Liu ◽  
Fang Zhu ◽  
Li Juan He ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fungal Infections ◽  
Nuclear Factor Κb ◽  
Mitogen Activated Protein Kinase ◽  
Host Recognition ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Opportunistic Human Pathogen

Fungi can shield surface pathogen-associated molecular patterns (PAMPs) for evading host immune attack. The most common and opportunistic human pathogen,Candida albicans, can shield β-(1 3)-glucan on the cell wall, one of the major PAMPs, to avoid host phagocyte Dectin-1 recognition. The way to interfere in the shielding process for more effective antifungal defense is not well established. In this study, we found that deletion of theC. albicansGPI7gene, which was responsible for adding ethanolaminephosphate to the second mannose in glycosylphosphatidylinositol (GPI) biosynthesis, could block the attachment of most GPI-anchored cell wall proteins (GPI-CWPs) to the cell wall and subsequently unmask the concealed β-(1,3)-glucan. Neutrophils could kill the uncloakedgpi7mutant more efficiently with an augmented respiratory burst. Thegpi7mutant also stimulated Dectin-1-dependent immune responses of macrophages, including activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways and secretion of specific cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and IL-12p40. Furthermore, thegpi7null mutant could induce an enhanced inflammatory response through promoting significant recruitment of neutrophils and monocytes and could stimulate stronger Th1 and Th17 cell responses to fungal infectionsin vivo. Thesein vivophenotypes also were Dectin-1 dependent. Thus, we assume that GPI-CWPs are involved in the immune mechanism ofC. albicansescaping from host recognition by Dectin-1. Our studies also indicate that the blockage of GPI anchor synthesis is a strategy to inhibitC. albicansevading host recognition.

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