Transcription factor Liv4 is required for growth and pathogenesis of Cryptococcus neoformans

ABSTRACT Cryptococcus neoformans is an important invasive fungal pathogen that causes life-threatening meningoencephalitis in humans. Its biological and pathogenic regulatory mechanisms remain largely unknown, particularly due to the presence of those core transcription factors (TFs). Here, we conducted a detailed characterization of the TF Liv4 in the biology and virulence of C. neoformans. Deletion of TF Liv4 protein resulted in growth defect under both normal and stress conditions (such as high temperature and cell wall/membrane damaging agents), drastic morphological damage and also attenuated virulence in C. neoformans. These phenotypic changes might be contributed to transcriptional abnormality in the liv4Δ mutant, in which several cryptococcal genes involved in energy metabolism and cell wall integrity were downregulated. Furthermore, ChIP-seq and ChIP-qPCR assays suggested TF Liv4 might exert its regulatory function in transcription by its activation of RBP1 in C. neoformans. Taken together, our work highlights the importance of TF Liv4 in the growth and virulence of C. neoformans, and it facilitates a better understanding of cryptococcal pathogenesis mechanisms.

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The interplay of phenotype and genotype in Cryptococcus neoformans disease

Bioscience Reports ◽

10.1042/bsr20190337 ◽

2020 ◽

Vol 40 (10) ◽

Author(s):

Sophie Altamirano ◽

Katrina M. Jackson ◽

Kirsten Nielsen

Keyword(s):

Patient Outcome ◽

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Proper Treatment ◽

Rapid Adaptation ◽

Complete Understanding ◽

Phenotypic Changes ◽

Life Threatening ◽

Opportunistic Fungal Pathogen

Abstract Cryptococcus neoformans is an opportunistic fungal pathogen that causes life-threatening meningitis primarily in immunocompromised individuals. In order to survive and proliferate during infection, C. neoformans must adapt to a variety of stresses it encounters within the host. Patient outcome depends on the interaction between the pathogen and the host. Understanding the mechanisms that C. neoformans uses to facilitate adaptation to the host and promote pathogenesis is necessary to better predict disease severity and establish proper treatment. Several virulence phenotypes have been characterized in C. neoformans, but the field still lacks a complete understanding of how genotype and phenotype contribute to clinical outcome. Furthermore, while it is known that C. neoformans genotype impacts patient outcome, the mechanisms remain unknown. This lack of understanding may be due to the genetic heterogeneity of C. neoformans and the extensive phenotypic variation observed between and within isolates during infection. In this review, we summarize the current understanding of how the various genotypes and phenotypes observed in C. neoformans correlate with human disease progression in the context of patient outcome and recurrence. We also postulate the mechanisms underlying the genetic and phenotypic changes that occur in vivo to promote rapid adaptation in the host.

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Characterization of the 6-O-acetylated lipoglucuronomannogalactan a novel Cryptococcus neoformans cell wall polysaccharide

Carbohydrate Research ◽

10.1016/j.carres.2019.01.012 ◽

2019 ◽

Vol 475 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Jose O. Previato ◽

Evguenii Vinogradov ◽

Maria Alice Esteves Silva ◽

Priscila.A.V. Oliveira ◽

Leonardo M. Fonseca ◽

...

Keyword(s):

Cell Wall ◽

Cryptococcus Neoformans ◽

Cell Wall Polysaccharide

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Cell Wall Chitosan Is Necessary for Virulence in the Opportunistic Pathogen Cryptococcus neoformans

Eukaryotic Cell ◽

10.1128/ec.05138-11 ◽

2011 ◽

Vol 10 (9) ◽

pp. 1264-1268 ◽

Cited By ~ 66

Author(s):

Lorina G. Baker ◽

Charles A. Specht ◽

Jennifer K. Lodge

Keyword(s):

Cell Wall ◽

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Slow Growth ◽

Opportunistic Pathogen ◽

Mammalian Host ◽

Cell Integrity ◽

Content Type ◽

Opportunistic Fungal Pathogen ◽

Chitin And Chitosan

ABSTRACTCryptococcus neoformansis an opportunistic fungal pathogen that causes meningoencephalitis. Its cell wall is composed of glucans, proteins, chitin, and chitosan. Multiple genetic approaches have defined a chitosan-deficient syndrome that includes slow growth and decreased cell integrity. Here we demonstrate chitosan is necessary for virulence and persistence in the mammalian host.

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Characterization of Lipids and Proteins Associated to the Cell Wall of the Acapsular Mutant Cryptococcus neoformans Cap 67

Journal of Eukaryotic Microbiology ◽

10.1111/jeu.12213 ◽

2015 ◽

Vol 62 (5) ◽

pp. 591-604 ◽

Cited By ~ 3

Author(s):

Larissa V. G. Longo ◽

Ernesto S. Nakayasu ◽

Jhon H. S. Pires ◽

Felipe Gazos-Lopes ◽

Milene C. Vallejo ◽

...

Keyword(s):

Cell Wall ◽

Cryptococcus Neoformans

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Central Nervous System Vasculitis for Cryptococcosis in an Immunocompetent Patient

Diseases ◽

10.3390/diseases6030075 ◽

2018 ◽

Vol 6 (3) ◽

pp. 75 ◽

Cited By ~ 1

Author(s):

Dan Zimelewicz Oberman ◽

Liliana Patrucco ◽

Carolina Cuello Oderiz

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Cryptococcus Neoformans ◽

Cryptococcal Meningitis ◽

Fungal Pathogen ◽

Immunocompetent Patient ◽

Central Nervous System Vasculitis ◽

Diagnostic Challenge ◽

Threatening Condition ◽

Life Threatening

Cryptococcal meningitis is a life-threatening condition caused by a fungal pathogen, Cryptococcus neoformans, that can infect both immunosuppressed and immunocompetent hosts. It is an important cause of morbidity and mortality in severely immunodeficient patients. However, in an immunocompetent patient it represents a diagnostic challenge, mainly because it is extremely rare, but also because of its nonspecific clinical manifestation. Neurovascular involvement in cryptococcal meningitis is rare and not well known and only few reports have described this association. We describe a cryptococcal meningitis in an immunocompetent patient associated with central nervous system vasculitis.

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Characterization of the MFα pheromone of the human fungal pathogen Cryptococcus neoformans

Molecular Microbiology ◽

10.1046/j.1365-2958.2000.02213.x ◽

2002 ◽

Vol 38 (5) ◽

pp. 1017-1026 ◽

Cited By ~ 48

Author(s):

Robert C. Davidson ◽

Tracey D. E. Moore ◽

Audrey R. Odom ◽

Joseph Heitman

Keyword(s):

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Human Fungal Pathogen

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The Ess1 prolyl isomerase is dispensable for growth but required for virulence in Cryptococcus neoformans

Microbiology ◽

10.1099/mic.0.27786-0 ◽

2005 ◽

Vol 151 (5) ◽

pp. 1593-1605 ◽

Cited By ~ 16

Author(s):

Ping Ren ◽

Anne Rossettini ◽

Vishnu Chaturvedi ◽

Steven D. Hanes

Keyword(s):

Rna Polymerase Ii ◽

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Virulence Genes ◽

Prolyl Isomerase ◽

Human Fungal Pathogen ◽

Genes Encoding ◽

Urease Production ◽

Fk506 Binding Proteins

Cryptococcus neoformans is an important human fungal pathogen that also serves as a model for studies of fungal pathogenesis. C. neoformans contains several genes encoding peptidyl-prolyl cis/trans isomerases (PPIases), enzymes that catalyse changes in the folding and conformation of target proteins. Three distinct classes of PPIases have been identified: cyclophilins, FK506-binding proteins (FKBPs) and parvulins. This paper reports the cloning and characterization of ESS1, which is believed to be the first (and probably only) parvulin-class PPIase in C. neoformans. It is shown that ESS1 from C. neoformans is structurally and functionally homologous to ESS1 from Saccharomyces cerevisiae, which encodes an essential PPIase that interacts with RNA polymerase II and plays a role in transcription. In C. neoformans, ESS1 was found to be dispensable for growth, haploid fruiting and capsule formation. However, ESS1 was required for virulence in a murine model of cryptococcosis. Loss of virulence might have been due to the defects in melanin and urease production observed in ess1 mutants, or to defects in transcription of as-yet-unidentified virulence genes. The fact that Ess1 is not essential in C. neoformans suggests that, in this organism, some of its functions might be subsumed by other prolyl isomerases, in particular, cyclophilins Cpa1 or Cpa2. This is supported by the finding that ess1 mutants were hypersensitive to cyclosporin A. C. neoformans might therefore be a useful organism in which to investigate crosstalk among different families of prolyl isomerases.

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Biochemical and Kinetic Characterization of Xylulose 5-Phosphate/Fructose 6-Phosphate Phosphoketolase 2 (Xfp2) from Cryptococcus neoformans

Eukaryotic Cell ◽

10.1128/ec.00055-14 ◽

2014 ◽

Vol 13 (5) ◽

pp. 657-663 ◽

Cited By ~ 9

Author(s):

Katie Glenn ◽

Cheryl Ingram-Smith ◽

Kerry S. Smith

Keyword(s):

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Allosteric Regulation ◽

Valuable Insight ◽

Kinetic Characterization ◽

Content Type ◽

Metabolic Role ◽

Separate Site ◽

Opportunistic Fungal Pathogen

ABSTRACTXylulose 5-phosphate/fructose 6-phosphate phosphoketolase (Xfp), previously thought to be present only in bacteria but recently found in fungi, catalyzes the formation of acetyl phosphate from xylulose 5-phosphate or fructose 6-phosphate. Here, we describe the first biochemical and kinetic characterization of a eukaryotic Xfp, from the opportunistic fungal pathogenCryptococcus neoformans, which has twoXFPgenes (designatedXFP1andXFP2). Our kinetic characterization ofC. neoformansXfp2 indicated the existence of both substrate cooperativity for all three substrates and allosteric regulation through the binding of effector molecules at sites separate from the active site. Prior to this study, Xfp enzymes from two bacterial genera had been characterized and were determined to follow Michaelis-Menten kinetics.C. neoformansXfp2 is inhibited by ATP, phosphoenolpyruvate (PEP), and oxaloacetic acid (OAA) and activated by AMP. ATP is the strongest inhibitor, with a half-maximal inhibitory concentration (IC50) of 0.6 mM. PEP and OAA were found to share the same or have overlapping allosteric binding sites, while ATP binds at a separate site. AMP acts as a very potent activator; as little as 20 μM AMP is capable of increasing Xfp2 activity by 24.8% ± 1.0% (mean ± standard error of the mean), while 50 μM prevented inhibition caused by 0.6 mM ATP. AMP and PEP/OAA operated independently, with AMP activating Xfp2 and PEP/OAA inhibiting the activated enzyme. This study provides valuable insight into the metabolic role of Xfp within fungi, specifically the fungal pathogenCryptococcus neoformans, and suggests that at least some Xfps display substrate cooperative binding and allosteric regulation.

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A Chitin Synthase and Its Regulator Protein Are Critical for Chitosan Production and Growth of the Fungal Pathogen Cryptococcus neoformans

Eukaryotic Cell ◽

10.1128/ec.4.11.1902-1912.2005 ◽

2005 ◽

Vol 4 (11) ◽

pp. 1902-1912 ◽

Cited By ~ 142

Author(s):

Isaac R. Banks ◽

Charles A. Specht ◽

Maureen J. Donlin ◽

Kimberly J. Gerik ◽

Stuart M. Levitz ◽

...

Keyword(s):

Cell Wall ◽

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Liquid Culture ◽

Chitin Synthase ◽

Yeast Cells ◽

Chitin Synthesis ◽

Chitin Synthases ◽

Regulator Protein ◽

Chitin And Chitosan

ABSTRACT Chitin is an essential component of the cell wall of many fungi. Chitin also can be enzymatically deacetylated to chitosan, a more flexible and soluble polymer. Cryptococcus neoformans is a fungal pathogen that causes cryptococcal meningoencephalitis, particularly in immunocompromised patients. In this work, we show that both chitin and chitosan are present in the cell wall of vegetatively growing C. neoformans yeast cells and that the levels of both rise dramatically as cells grow to higher density in liquid culture. C. neoformans has eight putative chitin synthases, and strains with any one chitin synthase deleted are viable at 30°C. In addition, C. neoformans genes encode three putative regulator proteins, which are homologs of Saccharomyces cerevisiae Skt5p. None of these three is essential for viability. However, one of the chitin synthases (Chs3) and one of the regulators (Csr2) are important for growth. Cells with deletions in either CHS3 or CSR2 have several shared phenotypes, including sensitivity to growth at 37°C. The similarity of their phenotypes also suggests that Csr2 specifically regulates chitin synthesis by Chs3. Lastly, both chs3Δ and the csr2Δ mutants are defective in chitosan production, predicting that Chs3-Csr2 complex with chitin deacetylases for conversion of chitin to chitosan. These data suggest that chitin synthesis could be an excellent antifungal target.

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