scholarly journals The Role of Dimorphism Regulating Histidine Kinase (Drk1) in the Pathogenic Fungus Paracoccidioides brasiliensis Cell Wall

2021 ◽  
Vol 7 (12) ◽  
pp. 1014
Author(s):  
Marina Valente Navarro ◽  
Yasmin Nascimento de Barros ◽  
Wilson Dias Segura ◽  
Alison Felipe Alencar Chaves ◽  
Grasielle Pereira Jannuzzi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Histidine Kinase ◽  
Mammalian Cells ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Fungal Resistance ◽  
Phagocytic Index ◽  
Mammalian Host ◽  
Control Group

Dimorphic fungi of the Paracoccidioides genus are the causative agents of paracoccidioidomycosis (PCM), an endemic disease in Latin America with a high incidence in Brazil. This pathogen presents as infective mycelium at 25 °C in the soil, reverting to its pathogenic form when inhaled by the mammalian host (37 °C). Among these dimorphic fungal species, dimorphism regulating histidine kinase (Drk1) plays an essential role in the morphological transition. These kinases are present in bacteria and fungi but absent in mammalian cells and are important virulence and cellular survival regulators. Hence, the purpose of this study was to investigate the role of PbDrk1 in the cell wall modulation of P. brasiliensis. We observed that PbDrk1 participates in fungal resistance to different cell wall-disturbing agents by reducing viability after treatment with iDrk1. To verify the role of PbDRK1 in cell wall morphogenesis, qPCR results showed that samples previously exposed to iDrk1 presented higher expression levels of several genes related to cell wall modulation. One of them was FKS1, a β-glucan synthase that showed a 3.6-fold increase. Furthermore, confocal microscopy analysis and flow cytometry showed higher β-glucan exposure on the cell surface of P. brasiliensis after incubation with iDrk1. Accordingly, through phagocytosis assays, a significantly higher phagocytic index was observed in yeasts treated with iDrk1 than the control group, demonstrating the role of PbDrk1 in cell wall modulation, which then becomes a relevant target to be investigated. In parallel, the immune response profile showed increased levels of proinflammatory cytokines. Finally, our data strongly suggest that PbDrk1 modulates cell wall component expression, among which we can identify β-glucan. Understanding this signalling pathway may be of great value for identifying targets of antifungal molecular activity since HKs are not present in mammals.

scholarly journals Protein Glycosylation inAspergillus fumigatusIs Essential for Cell Wall Synthesis and Serves as a Promising Model of Multicellular Eukaryotic Development

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Cheng Jin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Posttranslational Modification ◽  
Mammalian Cells ◽  
Protein Glycosylation ◽  
Cell Wall Synthesis ◽  
Fungal Cell ◽  
Multiple Functions ◽  
Significant Attention

Glycosylation is a conserved posttranslational modification that is found in all eukaryotes, which helps generate proteins with multiple functions. Our knowledge of glycosylation mainly comes from the investigation of the yeastSaccharomyces cerevisiaeand mammalian cells. However, during the last decade, glycosylation in the human pathogenic moldAspergillus fumigatushas drawn significant attention. It has been revealed that glycosylation inA. fumigatusis crucial for its growth, cell wall synthesis, and development and that the process is more complicated than that found in the budding yeastS. cerevisiae. The present paper implies that the investigation of glycosylation inA. fumigatusis not only vital for elucidating the mechanism of fungal cell wall synthesis, which will benefit the design of new antifungal therapies, but also helps to understand the role of protein glycosylation in the development of multicellular eukaryotes. This paper describes the advances in functional analysis of protein glycosylation inA. fumigatus.

scholarly journals Drk1, a Dimorphism Histidine Kinase, Contributes to Morphology, Virulence, and Stress Adaptation in Paracoccidioides brasiliensis

2021 ◽  
Vol 7 (10) ◽  
pp. 852
Author(s):  
Caroline Maria Marcos ◽  
Haroldo Cesar de Oliveira ◽  
Patrícia Akemi Assato ◽  
Rafael Fernando Castelli ◽  
Ana Marisa Fusco-Almeida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Latin American ◽  
Histidine Kinase ◽  
Paracoccidioides Brasiliensis ◽  
Yeast Cells ◽  
Lower Amount ◽  
Stress Adaptation ◽  
Infection Model ◽  
Dimorphic Fungus ◽  
Virulence Attenuation

P. brasiliensis is a thermally dimorphic fungus belonging to Paracoccidioides complex, causative of a systemic, endemic mycosis limited to Latin American countries. Signal transduction pathways related to important aspects as surviving, proliferation according to the biological niches are linked to the fungal pathogenicity in many species, but its elucidation in P. brasiliensis remains poorly explored. As Drk1, a hybrid histidine kinase, plays regulators functions in other dimorphic fungi species, mainly in dimorphism and virulence, here we investigated its importance in P. brasilensis. We, therefore generated the respective recombinant protein, anti-PbDrk1 polyclonal antibody and a silenced strain. The Drk1 protein shows a random distribution including cell wall location that change its pattern during osmotic stress condition; moreover the P. brasiliensis treatment with anti-PbDrk1 antibody, which does not modify the fungus’s viability, resulted in decreased virulence in G. mellonella model and reduced interaction with pneumocytes. Down-regulating PbDRK1 yielded phenotypic alterations such as yeast cells with more elongated morphology, virulence attenuation in G. mellonella infection model, lower amount of chitin content, increased resistance to osmotic and cell wall stresses, and also caspofungin, and finally increased sensitivity to itraconazole. These observations highlight the importance of PbDrk1 to P. brasiliensis virulence, stress adaptation, morphology, and cell wall organization, and therefore it an interesting target that could help develop new antifungals.

The schistosome in the mammalian host: understanding the mechanisms of adaptation

Parasitology ◽  
2007 ◽  
Vol 134 (11) ◽  
pp. 1477-1526 ◽  
Author(s):  
J. R. KUSEL ◽  
B. H. AL-ADHAMI ◽  
M. J. DOENHOFF
Keyword(s):  
Mammalian Cells ◽  
Surface Membrane ◽  
Membrane Rafts ◽  
Mammalian Host ◽  
Internal Organs ◽  
Parasite Communities ◽  
Mechanisms Of Adaptation ◽  
Future Work ◽  
The Relationship

SUMMARYIn this review, we envisage the host environment, not as a hostile one, since the schistosome thrives there, but as one in which the relationship between the two organisms consists of constant communication, through signalling mechanisms involving sense organs, surface glycocalyx, surface membrane and internal organs of the parasite, with host fluids and cells. The surface and secretions of the schistosome egg have very different properties from those of other parasite stages, but adapted for the dispersal of the eggs and for the preservation of host liver function. We draw from studies of mammalian cells and other organisms to indicate how further work might be carried out on the signalling function of the surface glycocalyx, the raft structure of the surface and existence of pores in the surface membrane, the repair of the surface membrane, the role of the membrane structure in ion channel function (including recent work on the actin cytoskeleton and calcium channels) and the possible role of P-glycoproteins in the adaptation of the parasite to its environment. We are speculative in some areas, such as the suggestions that variability in surface properties of schistosomes may relate to the existence of membrane rafts and that parasite communities may exhibit quorum sensing. This speculative approach is adopted with the hope that future work on the whole organisms and their interactions will be encouraged.

scholarly journals The role of the histidine kinase [) gene in the regulation of cell wall mannan and glucan biosynthesis

2003 ◽  
Vol 3 (3) ◽  
pp. 289-299 ◽  
Author(s):  
M KRUPPA ◽  
T GOINS ◽  
J CUTLER ◽  
D LOWMAN ◽  
D WILLIAMS ◽  
...  
Keyword(s):  
Cell Wall ◽  
Histidine Kinase ◽  
Kinase Gene ◽  
Cell Wall Mannan

scholarly journals Role for Chitin and Chitooligomers in the Capsular Architecture of Cryptococcus neoformans

2009 ◽  
Vol 8 (10) ◽  
pp. 1543-1553 ◽  
Author(s):  
Fernanda L. Fonseca ◽  
Leonardo Nimrichter ◽  
Radames J. B. Cordero ◽  
Susana Frases ◽  
Jessica Rodrigues ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Pathogenic Fungus ◽  
Monosaccharide Composition ◽  
Altered Expression ◽  
Functional Activities ◽  
Differential Reactivity ◽  
Human Pathogenic Fungus

ABSTRACT Molecules composed of β-1,4-linked N-acetylglucosamine (GlcNAc) and deacetylated glucosamine units play key roles as surface constituents of the human pathogenic fungus Cryptococcus neoformans. GlcNAc is the monomeric unit of chitin and chitooligomers, which participate in the connection of capsular polysaccharides to the cryptococcal cell wall. In the present study, we evaluated the role of GlcNAc-containing structures in the assembly of the cryptococcal capsule. The in vivo expression of chitooligomers in C. neoformans varied depending on the infected tissue, as inferred from the differential reactivity of yeast forms to the wheat germ agglutinin (WGA) in infected brain and lungs of rats. Chromatographic and dynamic light-scattering analyses demonstrated that glucuronoxylomannan (GXM), the major cryptococcal capsular component, interacts with chitin and chitooligomers. When added to C. neoformans cultures, chitooligomers formed soluble complexes with GXM and interfered in capsular assembly, as manifested by aberrant capsules with defective connections with the cell wall and no reactivity with a monoclonal antibody to GXM. Cultivation of C. neoformans in the presence of an inhibitor of glucosamine 6-phosphate synthase resulted in altered expression of cell wall chitin. These cells formed capsules that were loosely connected to the cryptococcal wall and contained fibers with decreased diameters and altered monosaccharide composition. These results contribute to our understanding of the role played by chitin and chitooligosaccharides on the cryptococcal capsular structure, broadening the functional activities attributed to GlcNAc-containing structures in this biological system.

Investigation of the role of complement and complement receptors in the modulation of B cell activation by a Paracoccidioides brasiliensis cell wall fraction

2006 ◽  
Vol 118 (2-3) ◽  
pp. 324-331 ◽  
Author(s):  
Carla de Agostino Biella ◽  
Marilei Uecker ◽  
Marcelo Fernandes da Silva ◽  
José Elpidio Barbosa ◽  
Célio Lopes Silva ◽  
...  
Keyword(s):  
Cell Wall ◽  
B Cell ◽  
Cell Activation ◽  
Paracoccidioides Brasiliensis ◽  
Complement Receptors ◽  
Cell Wall Fraction ◽  
B Cell Activation

scholarly journals Sophisticated Functions for a Simple Molecule: The Role of Glucosylceramides in Fungal Cells

2008 ◽  
Vol 2 ◽  
pp. LPI.S1014 ◽  
Author(s):  
Leonardo Nimrichter ◽  
Marcio L. Rodrigues ◽  
Eliana Barreto-Bergter ◽  
Luiz R. Travassos
Keyword(s):  
Cell Wall ◽  
Immune System ◽  
Building Block ◽  
Mammalian Cells ◽  
Recent Literature ◽  
Antifungal Drugs ◽  
Cell Wall Assembly ◽  
Wall Assembly ◽  
Ceramide Moiety

It is well known that mammalian glycosphingolipids (GSL) play key roles in different physiological and pathophysiological processes. The simplest GSL, glucosylceramide (GlcCer), is formed through the enzymatic transfer of glucose to a ceramide moiety. In mammalian cells this molecule is the building block for the synthesis of lactosylceramides and many other complex GSLs. In fungal cells GlcCer is a major neutral GSL that has been considered during decades merely as a structural component of cell membranes. The recent literature, however, describes the participation of fungal GlcCer in vital processes such as secretion, cell wall assembly, recognition by the immune system and regulation of virulence. In this review we discuss the most recent information regarding fungal GlcCer, including (i) new aspects of GlcCer metabolism, (ii) the involvement of these molecules in virulence mechanisms, (iii) their role as targets of new antifungal drugs and immunotherapeutic agents and, finally, (v) their potential participation on cellular signaling in response to different stimuli.

Thioridazine inhibits gene expression control of the cell wall signaling pathway (CWI) in the human pathogenic fungus Paracoccidioides brasiliensis

2016 ◽  
Vol 291 (3) ◽  
pp. 1347-1362 ◽  
Author(s):  
Daniela Leite Jabes ◽  
Ana Claudia de Freitas Oliveira ◽  
Valquíria Campos Alencar ◽  
Fabiano Bezerra Menegidio ◽  
Débora Liliane Souza Reno ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Wall ◽  
Signaling Pathway ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Expression Control ◽  
Gene Expression Control ◽  
Human Pathogenic Fungus

scholarly journals The PbMDJ1 Gene Belongs to a Conserved MDJ1/LON Locus in Thermodimorphic Pathogenic Fungi and Encodes a Heat Shock Protein That Localizes to both the Mitochondria and Cell Wall of Paracoccidioides brasiliensis

2006 ◽  
Vol 5 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Wagner L. Batista ◽  
Alisson L. Matsuo ◽  
Luciane Ganiko ◽  
Tânia F. Barros ◽  
Thiago R. Veiga ◽  
...  
Keyword(s):  
Cell Wall ◽  
Heat Shock ◽  
Cell Surface ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Yeast Cells ◽  
Shock Proteins

ABSTRACT J-domain (DnaJ) proteins, of the Hsp40 family, are essential cofactors of their cognate Hsp70 chaperones, besides acting as independent chaperones. In the present study, we have demonstrated the presence of Mdj1, a mitochondrial DnaJ member, not only in the mitochondria, where it is apparently sorted, but also in the cell wall of Paracoccidioides brasiliensis, a thermodimorphic pathogenic fungus. The molecule (PbMdj1) was localized to fungal yeast cells using both confocal and electron microscopy and also flow cytometry. The anti-recombinant PbMdj1 antibodies used in the reactions specifically recognized a single 55-kDa mitochondrial and cell wall (alkaline β-mercaptoethanol extract) component, compatible with the predicted size of the protein devoid of its matrix peptide-targeting signal. Labeling was abundant throughout the cell wall and especially in the budding regions; however, anti-PbMdj1 did not affect fungal growth in the concentrations tested in vitro, possibly due to the poor access of the antibodies to their target in growing cells. Labeled mitochondria stood preferentially close to the plasma membrane, and gold particles were detected in the thin space between them, toward the cell surface. We show that Mdj1 and the mitochondrial proteinase Lon homologues are heat shock proteins in P. brasiliensis and that their gene organizations are conserved among thermodimorphic fungi and Aspergillus, where the genes are adjacent and have a common 5′ region. This is the first time a DnaJ member has been observed on the cell surface, where its function is speculative.

scholarly journals Vesicle-associated melanization in Cryptococcus neoformans

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 3860-3867 ◽  
Author(s):  
Helene C. Eisenman ◽  
Susana Frases ◽  
André M. Nicola ◽  
Marcio L. Rodrigues ◽  
Arturo Casadevall
Keyword(s):  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Extracellular Vesicles ◽  
Lipid A ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Spherical Particles ◽  
Human Pathogenic Fungus ◽  
Kinetics Of

Recently, several pathogenic fungi were shown to produce extracellular vesicles that contain various components associated with virulence. In the human pathogenic fungus Cryptococcus neoformans, these components included laccase, an enzyme that catalyses melanin synthesis. Spherical melanin granules have been observed in the cell wall of C. neoformans. Given that melanin granules have dimensions that are comparable to those of extracellular vesicles, and that metazoan organisms produce melanin in vesicular structures known as melanosomes, we investigated the role of vesicles in cryptococcal melanization. Extracellular vesicles melanized when incubated with the melanin precursor l-3,4-dihydroxyphenylalanine (l-DOPA). The kinetics of substrate incorporation into cells and vesicles was analysed using radiolabelled l-DOPA. The results indicated that substrate incorporation was different for cells and isolated vesicles. Acid-generated melanin ghosts stained with lipophilic dyes, implying the presence of associated lipid. A model for C. neoformans melanization is proposed that accounts for these observations and provides a mechanism for the assembly of melanin into relatively uniform spherical particles stacked in an orderly arrangement in the cell wall.

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